| Author | Message | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 182 Registered: 10-2002 |
Ooopsie.... Just noticed - in my July 30, 9:43 post, I mistyped F6 for emulsion tubes... shouldda been F 7.... sorry guys. Regards, Andy | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 180 Registered: 10-2002 |
Mark.... can't really argue with you, you're right. Guess it's just the difference between prefering old fashioned "natural" (i.e. Webers)... versus "Viagra" (i.e. blower).  | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 638 Registered: 5-2002 |
I love those throttle bodies. I put mukuni down draft carbs from a yamaha fzr1000 on a p-car a few years back and it worked out quite well, 350 hp at 8500 for 2.8 liter. The cams were similar to the P6, a lot of duration, but not as much lift as I would have preferred, 11:1 compression. It ran pretty well on the street. That was my last naturally aspirated hop-up. When I got the 308, I decided to go over to the dark side and installed a blower. I hate to say it, but i doubt I will ever do another naturally aspirated street car. IMO, the blower 350 hp 308 is a light year better on the street (actually better than OEM thanks to modern engine controls)than the 350 hp p-car. It was also cheaper to build. | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 176 Registered: 10-2002 |
Philip... I think I told you I'm running 150s. 130s are just a good place to start for a decent "streetable" P6 engine. Jets are cheap and easy to switch. Start with 130s and the F6 tubes, see how you like it.. then bump up the mains and venturis, and try F36 tubes. Yeah, Weber's emulsion tube numbering system is sortta perplexing... and I don't purport to really understand it.. only what some empyrical results have been. If the 130s don't cut it for you with F6s, try F36s with them, before you go up on the mains (I run F6s with the 150s.. bye bye Boxer, TR!!)... see how you like that. This is where a dyno comes in handy, though it's not as much fun as ripping around the block, lol. Best regards, Andy | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 175 Registered: 10-2002 |
Hans.... Actually, that's not quite correct. I've seen 2v 308's crank over 350hp at 8k with over 300 torque at 6500 with P6s - BUT, that's with high-comp, porting and jetting. Point is, you CAN gain a lot of worthwhile power, but you have to do the other stuff with it... no cams alone will do it. In fact, the only stand-alone mod that really makes any difference is bumping compression. The P6s are a nice duration grind, but my ideal would be that profile/lobe centers, but with more lift... 10mm would be ok. Bob Norwood once had some outfit in Louisiana grind a set with so much lift he had to cut into the cam covers for lobe clearance. Ran like a banshee though. The 308 2v's, contra 4v's, will readily respond to virtually any such tuning. But back to my original point - the #s I gave Philip (with the above provisos)will result in a streetable plus/minus 300 hp engine (depending on porting), with decent torque coming online at about 2k... I'd call that "streetable". Though it's still fun to watch snobbish head valets stall the thing, lol. Best regards, Andy | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 329 Registered: 7-2002 |
Andy Thanks for the clarification. One reflection: jetting is surprizingly mild (130 mains). Stock, my 40 series w/32mm chokes run 135s. Any idea how the F7 compares to the F36? I know there was little rhyme or reason to the Weber numbering on the emulsions. Philip | ||
| Hans E. Hansen (4re_gt4)
Intermediate Member Username: 4re_gt4 Post Number: 1601 Registered: 4-2002 |
Andrew: This is seriously good stuff. Perhaps it's greatest value is in deterring many of us from doing just this!! I've thought about engine mods, but with experienced advise, I think I'll just stay where I'm at. (P6 cams good, but must do compression. Bigger carbs to match, some loss in low torque, not much gain higher up. Hmmmm..... Sounds like Enzo got it right the first time.) | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 173 Registered: 10-2002 |
Philip... That advance is just where we got our best lower-end torque dyno numbers with the settings/timing I listed... and it passed the "seat of the pants test" on the street. It's not really much of a change from stock, but it did work. Regards, Andy | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 328 Registered: 7-2002 |
Andy Thanks for post. I'll do the chokes (34mm). Hi comp will have to wait a few months. As you may know I have the ability to tune the timing somewhat given the HPX, but what's the thought on the 34 or 35 degrees at 3000? I assume lifts the torque curve up, but it seems a lot of added advance low down. Thanks Philip | ||
| Andrew A. Illes (Andyilles)
Junior Member Username: Andyilles Post Number: 171 Registered: 10-2002 |
Philip... I finally found my old notes!! The best all around performance I managed with P-6 cammed 308s (AND hi-comp pistons with max flow porting).. I - 51/58 E - 64/44 36 chokes 130 mains F7 emulsions 200 air correctors 65 idles 50 pumps The I-48/62 .. E-65/45 settings were Michelotto's for the Group 4s. It's a good track setting, but you have zilch until about 3k RPM. Just depends where you want your fun. If you're having transition problems, drill out the lead plug behind the transition orfices and slightly oversize one hole at a time (highest first), until you get what you want. Works better than going to larger and larger idles. Lead "split-shot" fishing sinkers work fine to reseal (K-Mart). Contrary to some opinions on here, P6 cams can be entirely "streetable"... just depends how you time them... plus, it helps to know how to drive. IMHO, P6s are a waste unless you also go to high comp pistons and do the jetting. Might also consider recurving the distrib to hit max advance (35*) at 3k. Best regards, Andy | ||
| Russ Turner (Snj5)
Member Username: Snj5 Post Number: 339 Registered: 2-2003 |
Carl - Yes, a long time since Hockenheim and I still have the Mondial 3.2 (see profile). Philip - The 3.2 is about 3 weeks away from test running with 40 dcnf12s using 34mm venturis and 150main/195ac/.6idle/.6pump as base setting. Will try to get the first info out to you here soon (with pics). Will initially be using gas analyzer while looking for a dyno. It's in DC if you are nearby. While initially worried about being too rich, I am now a bit 'leaning' toward needing a smaller a/c (180?) to keep the high end rich enough. Would rather start a bit rich to prevent holing a piston. Feel pretty good about the 150 mains with the 34 venturi, as many 308 guys run 140s very successfully with 32s and the comp specs a 160 for a 36mm venturi. The .6 idle seems to be pretty good as well at cross comparison - as before, this will really effect idle to main circuit transition. The .6 pump is a bit of a wag, however. Of course, this could all go to poop in the real world..... While I do not have the specs handy, these jettings are richer than a 3.5 liter 2 valve Jalpa with 42dcnfs which uses a smaller main - 140 I think with 34 or 36 mm venturis. Here again with the 3.2 the issue is the difference 4 valves makes.... Anyone else have comment or experiance? thanks rt | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 327 Registered: 7-2002 |
Greg While I think you're correct, my thoughts are the opposite, which seems to coincide with Ferrari's practice with the 308 GT4 LM. Here's what I understand and why. Set up for the P6 was to close the intake valve at 62 degrees ABDC. In the Le Mans car, the intake cam was advanced 4 degrees to close at 58 degrees ABDC. Dema Elgin's advice to me is to advance the intake cam to help hold up the torque curve low down. Directionally this is consistent with the "stock" P6 (62) to LM (58) change. Given both the P6 duration and overlap coupled with a change to 34mm venturis, I am less worried about flow in the upper end of the rev range. Obviously for a pure track car, you'd set it up differently. I assume the Suzuki is running Mikuni TBs? any sense of how much machining to make them fit? If you proceed with the project, let us know/keep the Board posted. Sounds interesting. | ||
| Greg_gray (Greg_gray)
New member Username: Greg_gray Post Number: 5 Registered: 7-2003 |
Is it an idea to change the cam timing. You could retard the intake one tooth and this should greatly benefit your top end power. Also with the p6 cams by doing this you widen the lobe separation angle and as such you will quiten the idle down. Also a higher comp ratio can be afforded due to the wider LSA. The higher comp always helps with the idle quality also. With a wide LSA you need great flowing heads and it sounds like you have them. If you not aware there a graph which I can post that details the intake tract length that is optimum for the various revs. Also I have had an idea about using the Suzuki GSX-R throttle bodies. These work like a CV carb. You will need an engine management system to run them. They are quite cheap to buy 2nd hand. I.E less than a $1000 USD for 8 and that includes the stepper motor. This way you can optimise you velocities through the heads and build torque throughout the RPM band. Cheers Greg.   | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 326 Registered: 7-2002 |
Carl My 40 DCNF 40 series carbs run 135/55/F36/220 jets as standard. Flames from the Tubi on overrun on the stock cams so it is plenty rich for the stock cams. I too have the GT4/LM specs (which with 36mm venturis provide no guidance). However, given your experience with a P6 grind, could you recommend initial jetting for stock compression/32 mm venturis and stock compression/34mm venturis? I am going to the dyno to optimize. Any thoughts appreciated. | ||
| Carl Jones (Carl888)
New member Username: Carl888 Post Number: 3 Registered: 7-2003 |
Oh, BTW, another engine that resembles the 308 Ferrari in concept is the Lamborghini Urraco powerplant. The P250 ran a 10.4:1 CR and the P-300 a 10.0:1. Interesting! Carl. | ||
| Carl Jones (Carl888)
New member Username: Carl888 Post Number: 2 Registered: 7-2003 |
Hi Alan and Russ, Great to see you both here (I think the last time I spoke to Russ was when I was in Germany in 1999 for the Hockenheim GP. Do you still have the Mondial??). Anyway, some interesting stuff here. Firtly, I have uploaded the engine specs for the 308 GT/4 Le Mans engine. They are on the Yahoo! groups "Ferrari Technical" list. I don't want to take anyhting away from this excellent resource but don't wish to post 700K of files and be abused by those on a dial up! The specs are available here: http://autos.groups.yahoo.com/group/ferraritech/ in the "Files" section. If there is space to upload them here, please let me know. I do not consider what is commonly known as the P-6 grind suitable for the street in any shape or form assuming you do the other upgrades as well. If you go for that grind, and make the necessary carburation adjustments which are ESSENTIAL for the top end performance you will loose the bottom end. Simple as that. When my friend John and myself built that LM spec engine, we did try it with the stock carb set up and it actually ran pretty well. From memory the bottom end torque did suffer, but not that much. However, we only had 260 BHP at 7,000 and power fell off above that, not much more than a decent stock set up. But we gained an extra 47 BHP just by going with the carb specs for the LM engine. So you really have to attend to all aspects of the engine of you change the cams, so, compression, carbs, ignition, choke size etc. Please note, I'm no engineeer, just a friend and me built that LM angine and had a decent play with it. I am not saying that a P-6 grind is unstreetable, but when you make the carburation and ignition changes as the Factory suggested, it is. Maybe your experinces will be different in a stock engine, but from my tests, just to change the cams is a complete waste of time and money. Regards, Carl. | ||
| Alan Ing (Alan)
New member Username: Alan Post Number: 10 Registered: 2-2002 |
Simon, yup, should have kept the old cylinder head gasket, but it didn't come off in one piece. Also, didn't know any better so I threw it away about 2 years ago. I had to make one of those custom cylinder head removers. When the cylinder head finally moved it made a loud pop! Carl, good to hear from you again, I miss flist, but I just could not handle all the email. Tech questions interest me the most so this seems to be a good forum for me. Drop me an email sometime. Would love to hear how your doing and what your latest project is. I called Weisco a few years ago, and they pretty much told me they already have the specs and can make them for me if I want. When I called JE, they told me that I would have to provide the specs for them so. Things may have changed now, but since I do not know how to spec a piston, I bought my set through Concours Automotive in California especially since they raised the wrist pin height to match my 328 crank. I think they were about $1,200 or so (Don't really remember). Perhaps they have the spec more readily available now. Mark, thank you for your suggestions, I'll certainly consider them when I get to checking my valve clearances. Russ, my TWM setup is for a 2 valve motor. When I originally purchase the 4 DCNF style throttle bodies, I thought I could use the original linkage. Unfortunately on the TWM throttle bodies, the throttle plates have relocated higher than where the webers have them. Therefore the linkage would not work. Also, I wanted to aim the injectors from the center of the V. On a stock carbed 308, the carbs are all in the same direction. TWM was kind enough to attempt to make me a throttle linkage. But since they did not have an actual engine, its not perfect. I will need to relocate the throttle cable and possibly remake the mounting base for the linkage. Luckily I have access to a milling machine and lathe so I will be attempting to correct this in the future. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 322 Registered: 7-2002 |
Either way, gives me an excuse for a set of pistons...and valves...and guides..oh an a porting job while I am at it! Will let you know. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1223 Registered: 12-2001 |
I hope it works out Philip, if you use a dyno, it would be interesting to see the before and after numbers, torque specifically. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 321 Registered: 7-2002 |
Newman I understand your perspective. My point was others with direct experience of the cams don't appear to agree with the "sick whore from a toilet" analogy, it all depends on how they are set up (choice of carbs/venturis etc). Anyway, in a couple of weeks, I'll have direct experience and others can learn from my (expensive) experience. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1222 Registered: 12-2001 |
Mark, you are correct, you can run what ever cam you want but the correct combination is the key or it will be a big dissapointment. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1221 Registered: 12-2001 |
I understand the warm feeling one gets while pondering the fact that they are factory P6 cams but if they make your car slower on the street where the car is to be used, then its a mistake to install them IMO. Rare or not. An engine, ferrari or not with 8.8:1 static compression wont pull a sick whore off a toilet with a cam using 290 degrees duration. A number I have aimed for when building domestic engines is a dynamic compression no lower than 7:1 when a long duration cam is used and thats what determines my static compression ratio when selecting pistons. I would predict that my engine running just under 11:1 would loose torque with the P6 cams so it would only stand to reason that it would hurt a stock engine even more. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 320 Registered: 7-2002 |
I am concerned about a misleading impression being created about the P6 grind on an otherwise stock motor for street/track use versus a full race motor. These two are not the same and experience from one doesn't apply to the other. While I haven't got the cams in the car yet nor have I driven the car with such, I don't expect it to be as draconian as is being suggested. Here's why: I purchased the P6s from Jeff McCormick. Some of you may remember Jeff as he had his own shop for a while and has been a member of the Ferrari fraternity for years. Jeff ran the P6s with stock carbs/stock venturis, stock carbs with larger (36 mm) venturis and with some massive 44 or 48 mm carbs with big a** venturis (they were removed from a twin Lamborghini-engined race boat!). Did the work on the dyno to jet it right each time. Each iteration improved the top end breathing and reduced low end torque. By the final incarnation, the motor fell flat on its face at 2500 but turned into a demon at 5K through to at least 8K. Streetable? No. High HP. Yes. Clearly the 308 (or other) motors can be tuned through careful selection of components to produce a wide range of operating characteristics, some acceptable on the street, some not. In my case I am planning on staying (at least initially) with the 32mm venturis to help keep the low end of the torque curve up. We'll see how they work. BTW, with 290 degree duration, and an intake cam closing at 60 to 62 degrees ABDC (versus 46 for the GT4 cams), I calc that they'll reduce dynamic compression by about 12%. The before and after compression test will tell the tale. And, to Dave's question, yes I am planning some dyno time. Last, Bill Pound described the P6s to me as the Marilyn Monroe of cams (which I took to mean as having a fascination beyond its specifications). With modest lift (gross 9.7mm) and long duration (290), a "better" fast road grind can be made (more lift, shorter duration). But then, of course, they're not Ferrari... Will post the results as it comes together. To Russ's point, the biggest initial trick will be to avoid leanness and putting a hole in a piston. HTH | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 631 Registered: 5-2002 |
I've never tried P6 cams, but I have run similar and larger cams in other vehicles on the street without suffering ANY low of power at lower rpm. Quite the opposite, in every case the engines made more power at every point. The problem with building an engine with big cams it that it is very hard to tune. The porting, CR, and exhaust need to be right and the carburation must be spot-on. If those things are true, it will run great, if not, it will be the worst car you have ever driven. The more radical the engine, the more critical that everything matches. I wouldn't be in anyway afraid of P6 cams, just plan a day or 2 on the dyno to get it right, after you match all the other parts (porting, CR, ect) | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1220 Registered: 12-2001 |
16BHP at 3000rpm using P6 cams, Ill pass on that upgrade. I figured I would have WEB make a suitable grind for the street. | ||
| Russ Turner (Snj5)
Member Username: Snj5 Post Number: 336 Registered: 2-2003 |
Carl Likewise great to see you from FList and great to have your expertise. Would be very interested if you also have the Weber specs that matched the cam. Another respected mechanic here (JRV) once posted implying that the P-6 were a good street upgrade, so I'm wondering if Webers tuned for WOT might be a factor. Paul Sloan, another FChat member is in the middle of porting and putting pistons, cams and Weber 48 IDAs (!) on his 308QV (see archives for some amazing photos), so I'm sure he would be interested in this as well. Alan - I likewise found a set of Modena Engineering QV Weber manifolds and have seen the TWM pictures. I'm wildly interested in your linkage experience since am currently designing my own for a Weber 3.2 conversion, since the TWM linkage is for a 2v and told me they had no applicable QV/3.2 applications. As you know, this is because the water cross pipe/manifold arrangement is different on the 4 valve heads. Dave - will be doing exhaust gas analysis as well as seat of pants initially. Target is not total maximum power for me, but an improved response, character, reliability and aural performance. Will get close, then take to dyno. My biggest anticipated tuning bug will be the transition from idle to main circuit smoothness. Again, great to hear from everyone. best rt | ||
| Phil Hughes (Ferrarifixer)
New member Username: Ferrarifixer Post Number: 4 Registered: 7-2003 |
If you're in a hole and want an educated guess, a standard 308 head gasket will compress by about 10% of its new thickness. This may sound a bit vague, but multipied out into the final comp ratio, any small variation from this "educated guess" is almost totally irrelevant and will most likely be less than 0.05 from true ratio, which will have negligable affect on fuel and ignition requirements, and well within adjustment tolerances....that said, the only way to be 100% is to buy a sacrificial gasket....and check they're the same uncompressed thickness. For road use, 10.25:1 with standard cams and standard timing makes a really punchy engine that's tractable and torquey....and cost efficient! Small air corrector and main jet changes are all that's needed, and ignition to be about 10` BTDC at 1000rpm with Max advance of 33` at 5500. The distributor needs a small mod to achieve this. Remember...torque wins races, power wins friends. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 630 Registered: 5-2002 |
Alan, I usually use the old head gasket during fit ups if it came off in good shape...otherwise you need to bit the bullet and put a new one in. With new bigger cams, I first check the valve to valve clearance and with a degree wheel on the cam, lift at TDC if it wasn�t supplied by the cam maker both with the head on the bench because you want to be should the seat are at final height before you check piston clearance. Then I put the head on with the old head gasket, no cams, and no valve springs on the valves. Turn the engine to TDC and measure how far the valve move before hitting the piston. I if everything looks good, then I go to the cam and clay to confirm and measure the CR. I hope this was some help at least. | ||
| Carl Jones (Carl888)
New member Username: Carl888 Post Number: 1 Registered: 7-2003 |
Hi Alan, Nice to see some old names I met on the FerrariList some years ago here. I am sorry I cannot answer your question and in fact I am in the process of sourcing some parts for my 308 re-build. I am curious to know where you guys buy your JE and Weisco pictons from as both companies never replied to my email some months back. Can anyone suggest a dealer I could try. BTW. I have the engine specs for the 308 GT/4 LM car. I'd be happy to post it somewhere if you like. A friend and me built such and engine for a racecar in 1993. I can assure you, the P6 grind is completely unsuitable for the street. The engine produced 307 BHP at the flywheel at 8,000 rpm and 16 BHP at 3,000 rpm! Regards, Carl. | ||
| Simon Campbell (Simonc)
Junior Member Username: Simonc Post Number: 120 Registered: 2-2002 |
Hi Alan At the risk of asking the obvious, why can't measure the thickness of one of your old head gasket and calculate the volume from that? | ||
| Alan Ing (Alan)
New member Username: Alan Post Number: 9 Registered: 2-2002 |
Well, I haven't posted much at this site, but since everyone is talking about high compression 308 rebuilds I thought I would take this opportunity and ask a couple of questions about a 2 valve cylinder head gasket, specifically, does anyone one know the volume of the gasket? How about the installed thickness? I'm attempting to rebuild and modify my first ferrari engine (first engine ever actually). So far I've had the Cylinder heads rebuilt at Modena Engineering using Stainless valves and Titanium Retainers as well as a port job and a new set of performance cams. For the bottom end, I swapped my 308 crank for a 328 crank (small increase in stroke) and purchased a set of 10:1 JE pistons with the wrist pin relocated to match the 328 crank. One of the things I really want to do is to verify the new compression ratio and thats why I was wondering if anyone knew the volume of the cylinder head gasket. Would it be reasonable to just take a micrometer and measure the steel ring on a new gasket and calculate it or does the gasket compress enough to make a difference? Since I will be using a brand new set of cams, I am a bit concerned about piston to valve clearance. I know I could check this with a bit of clay, but am concerned that I will ruin my new expensive head gasket if I have to torque the cylinder head down, cycle the engine, and then remove the cylinder head to measure the clay. Will this harm the gasket? Just if anyone is curious, I had TWM Induction make me a set of 4 weber style fuel injection throttle bodies. If anyone one is curious, a picture of the setup is at www.twminduction.com. It is also on Mr. Sciana's Forza site (Not sure why a picture of my induction ended up on his site, but I suppose its okay as long as he is a TWM distributor). By the way, a custom linkage was made for this setup but unfortunately will take a bit more tinkering to work. If anyone else wants to purchase the same setup from TWM or perhaps though Nick, drop me a note and I'll fill you in on the details. Its not exactly a bolt on job. One of the sad stories of this rebuild project, is that Its been on hold for several years now. In fact the original Electromotive TEC II unit I bought to fuel inject the motor is no longer sold and is now the TEC III. Anyway, if someone one has any advice, I'd appreciate it. | ||
| dave handa (Davehanda)
Intermediate Member Username: Davehanda Post Number: 1361 Registered: 5-2001 |
All these posts are really cool. This is going to be some valuable information for future reference. Was wondering though; how are you guys going to finalize your carb jetting selections? Will you combine dyno runs with an exhaust analyzer? Just curious, as "seat of the pants" will get you close...but not always spot on. | ||
| Russ Turner (Snj5)
Member Username: Snj5 Post Number: 333 Registered: 2-2003 |
Philip thanks for the terrific reply - great information. We are all rooting for you! Mine starts going together in about 2 weeks (waiting on carbs), so will be following your progress closely. I am only increasing to 34mm venturis (308 comp was 36 I believe) to keep air column velocity. WEB cam calculated required venturi for a 300hp 3.2 liter v8 with individual throttles to be 33.5mm, thus the 34mm figure. I will ante in with .6 idle jets, 195a/c and 150 mains which they and Pierce Manifolds said sounded close. Good luck with your baby! Sounds great! best rt | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 319 Registered: 7-2002 |
Newman Here's what I suggest. Let me get it up running and then I'll try and provide a guide to how much louder than w/out the P6s. If you want to do the phone thing at that time, we can do that too. Newman, Russ, others On the P6s generally, this is a bit of a can of worms. First, P6s (if you can find factory parts) can "typically" be had for $2000 - 2500. They are few and far between, and not a particularly good grind for street use (290 duration results in low dynamic compression unless you are using a hi-comp piston [which I haven't done yet]). Others can opine from experience on the feel of the car with cams alone/with hi-comp pistons etc. Second, having found a set, the issue (for me) was the condition of the lobes. Two of lobes were worn out of "spec". This usually occurs through infrequent use and at servicing the tech not changing the valve shims even if the gaps appear OK (the shims dish over time and cause the lobes to wear). Material had to be added, then the lobes re-ground, heat treated and nitrided. The cams then needed to be checked for straightness, and re-straightened as needed. Third, if you are trying to put them back to spec/build a cam to P6 spec, there's debate on the exact specs for the cams. "Daytona" (12 cyl.) P6's appear to be a different grind than 308 P6s (despite being told and reading that they are the same). Infact, I had three well qualified sources provide conflicting P6 specs (on both lift [at nominated lash] and duration [where measurement error is more common due to ramps]). In reality, the lifts and the durations of "my 308" P6s (which Dema believes are factory originals) were identical within tolerance. Fourth, putting them in the car requires a small amount of custom fabrication for US spec cars (the ex cam doesn't run an air pump pulley) and a small disc with sealing ring needs to be made. Fifth, on jetting, I've not been able to find good data on how to change the jetting. Most qualified opinions suggest small changes to (larger) main jets (I have 135s now and will put in 140s to start), but the issue is likely to be as much at part throttle as WOT. A larger size of idle jets may also be needed. I'll post an update when it is running in a couple of weeks. Last, Russ, remember too, I am running stock carbs and stock secondary venturis. Increasing either of these (as I think you are doing) will change the power characteristics and the fuel requirements. I don't have the LeMans specs in front of me (but have posted them here before), but with larger primary and secondary venturis, the jetting was very different versus the street cars. HTH Philip | ||
| Russ Turner (Snj5)
Member Username: Snj5 Post Number: 332 Registered: 2-2003 |
Philip Do you have the recommeded jetting for the P-6 cams or an initial WAG? What changes? Can't wait to hear the results! best Russ | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 985 Registered: 5-2001 |
Newman, The key phrase is: - ie; Equal power. Of, coures, If you then use the higher power that's on tap in the higher compression engine, there'll come a (higher)power output where the heat generated by the lower compression engine at max power is exceeded. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1219 Registered: 12-2001 |
Interesting Mitch, I would have thought it would create more heat to go along with an increase in power. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1218 Registered: 12-2001 |
Philip, I do want to hear it but its a long drive from Toronto, you know, the sars infested area. Email me your number and I can call you for a listen over the phone. Or you can send me a sound clip or something. Either way I have to hear it. What other mods have you done to compliment the cam choice? Also, how much for the cams themselves? | ||
| Mitch Alsup (Mitch_alsup)
Member Username: Mitch_alsup Post Number: 892 Registered: 4-2002 |
"No oil consumption, no pinging and engine temp is under 195 on the hottest day in traffic." High compression is one means of getting more of the energy content in gasoline into the rotating members of an internal combustion engine. So, the higher the compression the lower the temperature that the engine will run (all other things being equal). So a 8:1 engine running down the hiway at 60 MPH will dump more heat into the water jackets than an 10:1 engine running down the hiway at 60 MPH. In addition, higher compression will allow one to extract more energy from the header system. The very small combustion volume durring overlap allows the pressure waves returning from the header to pass through the chamber and into the intake system more effectively at high compression than at lower compression. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 318 Registered: 7-2002 |
Newman Continental (Hinsdale, IL) are putting P6 cams in my 77 gtb. It has a Tubi so is already loud, sorry, L-O-U-D. It'll be louder still with the P6s. I'll be at Gingerman (South Haven, MI) for the Central States Region romp. If you are anywhere near, you are welcome to stop by, see/listen/ride etc. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1217 Registered: 12-2001 |
Anyone know the dome volume on a stock piston? | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1216 Registered: 12-2001 |
I rebuilt the engine, so everything was done at that time. Stock valve components other than the bmw viton guide seals. The carbs have 200AC, 140 mains and .55 idle jets. I will be going to a 195AC jet and 150 mains next. I have to increase the pump jet nozzles as well. It runs well but I think I can gain a little more with the jet change, especially the pump nozzles. Stock Euro single distributor with 7 degrees BTDC timing. Those jet selections will go out the window once the cams are done though. I would like to hear a 308 with P6 cams before going that route. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 317 Registered: 7-2002 |
Newman Did you have to do the valves at the same time? Is there an expectation on this upfront? | ||
| Russ Turner (Snj5)
Member Username: Snj5 Post Number: 330 Registered: 2-2003 |
Newman what carb jetting did you find worked best? do you know your advance settings? Many thanks rt | ||
| rich (Dino2400)
Member Username: Dino2400 Post Number: 404 Registered: 10-2001 |
The exact cam profile you will be using will have a lot to do with your need for octane. I installed "10.4" pistons in my Dino engine but while that means I had a static CR of 10.4:1, I could still run the car on 91 octane pump gas. I would mix in some higher octane when I happened by a station that had it but normally just the straight 91 was ok for noraml driving, even in the summer. This is because the important thing to consider is the dynamic compression ratio (or "effective"). A static measurement assumes a closed system. But dynamic takes into consideration that the intake valve(s) are still open past BDC and therefore the piston isn't building compression during its whole stroke. A knowledgable engine builder will be able to look at the static number, factor in the intake cam closing point and let you know if you will be over compressed to run on pump gas or not. Or you can post the cam specs and we can try to calculate it here. I suspect that I got away with 91 octane because of a combination of a fresh engine (little carbon build up to produce hot spots), cold spark plugs, and a late intake cam closing point (this probably limited my lower rpm torque but I had a GT car not a drag racer so I didn't care, ha!). | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1215 Registered: 12-2001 |
Sorry, no dyno numbers but it pulls harder than a stock one. Its still not in 348 territory but I may give a 328 a good run. I hope to find out at a meet we are having in Aug. | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1214 Registered: 12-2001 |
Im running stock cams unfortunately which I may be replacing this winter. Im running 94 sunoco gold and have no detonation problems. I believe the combination of aluminum with a hemi cubustion chamber allows for the higher ratio. I ran 11.5:1 on a late model LT1 camaro, monitored the knock signal via laptop and had no knock running the 94 octane fuel. Again, I think the heat dissapation of the aluminum heads along with the unusual reverse flow cooling system on that type of engine allowed me to get away with it. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 623 Registered: 5-2002 |
Newman, What octane gas do you run it on? Stock cams? | ||
| John_Miles (John_miles)
Junior Member Username: John_miles Post Number: 93 Registered: 7-2001 |
Any dyno results on that setup, Newman? | ||
| Newman (Newman)
Intermediate Member Username: Newman Post Number: 1213 Registered: 12-2001 |
Last year I installed weisco 10.8:1 3 ring pistons along wil mild porting, exhaust, carb rejetting and a single distributor setup. It cost $1700 cdn for the pistons with rings, pins and clips. They also weigh 100 grams less (each) than the originals. No oil consumption, no pinging and engine temp is under 195 on the hottest day in traffic. Ive put 13,000kms on it since without a hitch. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 316 Registered: 7-2002 |
What do a set of Weisco pistons run for the 2v heads? Assume you'd need to bore/re-sleeve too(?) Assume if you're doing all this you'd also need to look at valves, springs and guides. Feels like 10K including the labor without machining the heads? | ||
| Ben Cannon (Artherd)
Member Username: Artherd Post Number: 572 Registered: 6-2002 |
I'd stay away from anything over 10:1 on a non-knock controled street engine. You can safely run 11:1 or higher on pump gas if you have enough intake swirl and have knock control. c'mon, build a 13.5:1 8000rpm cammed avgas monster, you know you wanna ;) In any event, I'd go with the higher CR pistons long before I touched the heads on a 308. There just ain't a lot of metal (good thing, saves weight). Best! Ben. | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 315 Registered: 7-2002 |
I used a J&S ("John and Shirley") knock sensor on a supercharged Miata. Worked well. Quite good adjustability (threshold as it "listens" for knock) and the ability to retard either just one cylinder or all (four). As I recall, it would work on an eight too. I think it pulled up to six degrees of timing but this was several years ago so it may have improved/become more intelligent. Quite reasonably priced too. HTH | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1959 Registered: 11-2002 |
>>but it's BMEP that's important<< I agree...BMEP - Brake Mean Effective Pressure tells the real story. And what one should carefully look at when Tuning with the aid of a Dyno. Cool Link Rob. I'll read up on their stuff...I liked what I read just speed reading thru it. Billy, agree with you, I'd go Wiesco or J&E and Web Cam, definately a real ignition/FM system like Robs link, and ditch the carbs or CIS Inj., in favor of ITB EFI (or maybe even something I've been wanting to try BVorSV TB's w/EFI). making significant (40+) HP gains with NA Ferrari engines (V8's) takes more than bolting on a few Internal Parts. But the mods mentioned here do add enough to make the cars run like they should have all along, without taking away from durability. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 741 Registered: 11-2002 |
J&S Electronics FWIW, at LFSC we had 330 hp at the flywheel on the SCCA GT2 Michelotto car. CR was less than 11:1, but it's BMEP that's important. Large overlap can decrease effective cylider pressures. | ||
| billy bob (Fatbillybob)
Member Username: Fatbillybob Post Number: 300 Registered: 8-2002 |
Why bother with daytona pistons? Weisco makes them that will fit the 308 bores that are 10.5. They are way cheaper and you do not have to deck your head. the compression is built into the piston design. Also WEB cam in riverside, Ca. can do a P6 grind by swapping the exhaust cam to the intake and then welding up the intake cam and regrinding that to the p6 profile. You can run all this on pump gas with an electromotive tec2or 3 engine management system. So there you are I just saved you a few thousand dollars and you can spend it on the engine management. Also you will not solidly be into the 300hp range. Ferrari engines are difficult to massage more HP from. These are not chevys. Even with all this 280-300hp on the dyno is a very good number. Over 300hp maybe and barely. You are starting at best at 240hp. Everything you do adds a few percent HP. To be significant you have to do all these things including a 328 crank but by the time you do all this stuff you could have bought a 348 and got a better suspension for free! Anyway, I've done this excercise before. It is not worth the trouble but you sure learn a lot. Consider it the best education you ever got in Ferrari's. It is the thing to do for the love of the art. However, it is best to leave the driveable engine design to Ferrari. They really make all the best compromises for how the cars are drive 90% of the time. Now Racing that is a different story. | ||
| JRV (Jrvall)
Intermediate Member Username: Jrvall Post Number: 1956 Registered: 11-2002 |
I'd limit street compressin to about 10-1 unless you intend to upgrade to some form of anti-knock control. Just be careful milling the heads that they don't get into the edge of the seats and that the pistons have adequate reliefs cut in. | ||
| Don McCormick (Dandy_don)
Junior Member Username: Dandy_don Post Number: 82 Registered: 2-2002 |
Hi, I need some advice. I am engaged in a 308 engine rebuild project with a respected engine tuner/builder. The engine is a Euro dry sump 308 and will be fitted with P6 cams, 3 ring Daytona pistons and has ported and polished heads. Should be good for about 280-300 HP which sounds reasonable depending on tune/timing etc. The 3 ring Daytona pistons bump the compression ratio to about 9.7 to 1. The builder has asked me whether or not I would like him to shave the heads a small amount and bump the compression ratio to about 10.5-6 or so. He is concerned that the engine will ping on 91-92 octane but really believes that the added compression will put the engine solidly over the 300HP mark. Very cool, but not if the only gas I can run is avgas with octane of 100 or so. One of our number has offered his opinions on the matter off line but has suggested that I post the issue on this forum for some help. Specifically I am interested in the following: Is there any downside to shaving the heads to raise the compression ratio? ie the timing belt tensioning system or other similar issues. Clearly this is a non reversible modification. It seems clear that bumping the comp ratio to 10.5 to 1 will be a good thing with P6 cams (more power and broader band) but will I need to run higher octanes (avgas) with that ratio? and will the engine be streetable/driveable? I really would like to tap the vast breadth of experience here on the board without the differing opinions degenerating into a brawl so I do ask for some civility here. I just want your best thoughts. It is crystal clear to me that I haven't any of the necessary experience to make an informed decision and I feel the need for some discourse on the matter before coming to that decision. Thanx in advance for your thoughtful opinions on this matter. Don |