Well shyeaaaaaah. But do you care to share your modifications? I'm sure some of the 355 guys would like to make that kind of power. I'm gonna take a guess at some of the mods. Race port work on the heads Lighter valves with stiffer springs Higher lift cams High compression ratio pistons (13:1 or 14:1 ?) 360 crank Long rods Race headers Motec ecu and a 9150rpm rev limit Hi flow injectors Hi flow fuel pump Adjustable fuel pressure regulator Maps sensors instead of mafs Ported throttle bodies/or larger tb's Light weight flywheel How am I doin?
Race port work on the heads--at least as seen on my 355 heads, there is not a lot left to be done in the ports excepting a bit of port matching, and a 3-or-5 angle valve job (or eliptical if you head guy has the tooling). Lighter valves with stiffer springs--if you go with Titanium valves, get an extra thick valve head so the valve faces to not yield and cup inwards, loosing tappet clearance. Ti valves can be used with lighter springs since they are so much lighter themselves. Might want to use DLC coatings on the stems, though. The thick faces add compression-ratio to the cylinder volume. Higher lift cams--don't forget longer durration High compression ratio pistons (13:1 or 14:1 ?)-- to make up for the longer durration cams 360 crank Long rods--rod length is a function of the deck height of the block, the stroke of the crank, and finally the pin location in the piston. Assuming you want a 360 crank and have to stick with the 348 block, piston pin location is the only variable that needs to be matched to the rod length. Race headers--1.875" diameter, 24" long with a 2-1 merge-collector (6" long) output of 2.25" and a second 2-1 merge-collection (7" long) output of 3.0 inches and an expansion chamber at least 12 inches long. Packaging is the issue. Motec ecu and a 9150rpm rev limit -- more than 5000 fps mean piston speeds--danger Will Robinson... Hi flow injectors--obviously Hi flow fuel pump Adjustable fuel pressure regulator Maps sensors instead of mafs--if you go this far, you can use an O2 feedback alpha-N fuel injection strategy. Use the O2 sensors to train the long term tables and keep the mixture in the stoichiometric zone (or slightly rich::slightly) Ported throttle bodies/or larger tb's Light weight flywheel--with 30% stronger pressure plate. Might want to check if the 348 has piston squiters (like the F355) to keep the pistons cool and hold detonation at bay.
You forgot upgraded driveshaft. With all that power that is the FIRST thing to go. And bring a spare driveshaft wherever you go.
Very warm. You are missing a few pieces. My car I has never been Dyno'd. I am running a stock car in CCR. My car does not make 498 bhp, but I have seen a 355 in Orlando with 498 bhp. I am thinking about making the conversion to a 355 monster. So, I have been researching. Just trying to make the decision if this is what I want to do.
Those 348 rods would not need to be changed, in fact I would keep them or swap to 355/360 Ti rods which are the same length but use a 20mm pin rather than an 18.5mm pin. Just change the piston pin height to accomodate for the new stroke and you are good to go. I just finished my 3.4L 308 engine and stuffed a 360 crank into the thing and there was plenty of room on the pistons to move the pin higher. Rods are fine. Needless to say the car goes very well now! Not before a complete redesign of just about every internal moving part on the engine though! What a project, but worth it.
Interesting results ernie, aside from the higher HP reading, it seems this hub dyno calculates torque differently than the wheel dynos I have seen or used. On the other dynos, if the RPM was not accurate the HP would also not be accurate. So this cleared a lot of things up as far as what was charted. Thanks for doing that second dyno run ....... now I need to find out what my gear ratio is so I can do some runs on that 'generous' dyno ........ Vince, I did not know the 348 had that many delivered production ratios ........ the RPM discrepancy on your chart now makes sense, if you go up to the 4.75 from the 4.5 ratio used ........ and according to what happened to ernie's chart ........ you would be going in the same direction (from a lower to a higher ratio) This would indicate your RPMs would be corrected, your TQ would go lower and your HP would read the same as now. I guess you need the same 200 cell cats that ernie is running ...... On mitch's post above ........ piston speeds do not go 4+ times the speed of sound (5000fps), I think you meant FPM not FPS ....... 79mm 360 crank @9150RPM .... piston speeds will hit a tad over 79 FPS and about 4743 FPM 77mm 355 crank @9150RPM .... piston speeds will hit a tad over 77 FPS and about 4623 FPM Interesting on that 360 crank on a 308 ...... I am not sure it would work on a 348 or a 355 because of the different 360 flywheel interface when compared to a 348/355 ...... I looked into it a while back and the shop said it would be better to have a new crank made for the 348/355 .......
You indeed can place a 360 crank in a 348/355 block. I have had 355, 348, 360 cranks in hand to inspect and the only difference is the stroke length obviously. Otherwise they are interchangeable. The only issue is the obvious; 360 cranks are now stupidly difficult to locate and pricey when you can. They are incredibly light though, 31lbs compared to a 308 crank which is 41lbs. Crower WILL make a custom one-off crank for right around $3500 is the other option. sorry to derail, but: The below vid is revving to a little over 7k, I can't rev it really beyond that just yet as I'm waiting for the engine to have a few more miles on it, but it's easy to tell it goes well now! Anyway, it makes 348 power but probably a bit more torque. New billet high lift/duration cams, lots of intake porting, pistons, 360 crank, larger 44mm intake valves, larger seats, stiffer high lift valve springs, lots of carb mods. No stone unturned really. I haven't got it on the dyno just yet but I can tell there's a solid 250-260+ at the wheels there. Probably 310-320 at the crank, and the car weighs 2800lbs now so it's all sorts of old-school fun. http://www.youtube.com/watch?v=ECNMTdu72_k&feature=youtu.be
Your 308 sounds freaking great Fpilot !!! .... I watched both vids !!! ........ is it carbed or injected? What brand ignition/trigger setup did you use to go distributorless? Thanks for the clarification on the 360 crank ...... I guess I got some bad info in the past ... .......... if I were to open up the bottom end down the road ....... increasing the stroke would quite tempting .......
Well get it hooked up to a dyno son! And don't forget to get the final drive ratio correct. Nice video by the way, it sounds great!
It's a carbureted engine. I've got my hands around 90% of the jetting on it now. It's got some tricky spots like the low end loves going rich when I stab the throttle, but I nearly have that ironed out now with different pump jets and some timing/throttle plate adjustments. The cams are about as wild as a person can go for a street motor and they run uber. The ignition uses a 36-1 wheel I machined onto the damper and is a Megajolt system so it basically uses coils that are pretty much identical to 348/355 coils. I have the tach with one of our distinguished f-chat consultants in Germany being configured so it will read a square wave tach signal (I couldn't get it to read from any of the negative inductive signal wires no matter what I tried). I plan on changing to coil on plug once a specific ECU I like comes to market. Ernie, I'll get it on a dynojet soon and report back here. I have been making carburetor jetting changes, then datalogging the results over and over again and am almost there, and once I am I will dyno the thing.
Actually, I am more of the opinion that there are no speciale gears for my car, so I more likely to go with the same set Ernie has. The question remains, however, how did his older ride end up with the newer gear set? A mystery. Of course, if his car was in a rental fleet and abused by drunk sailors and inexperienced Japanese tourists, a transmission replacement makes sense. Anyway, I'm all up for the 200 cell cats. The real question is if I can pass smog with those. We shall see, I guess. Worse case, I got to replace those chips for the test. Anyone up for an engine rebuild using Fpilot's ideas? I might. I keep reading about the 400 Hp 308 engines by Caribou and Nick Forza. Why can't we do that? Should be eazier except for the ECU thing. Hmm, back to piggy backing the intake, I guess.
Throw a 79mm stroke 360 crank in a 348 engine and then contact Steve Wong who is known for his wizardry with mid 80s Porsche 911 Bosche DME units and chip making. I have no doubt he could program a chip which would make a 348 run very right in its new configuration. The other option is a bit more wild, and that is removing the DME altogether and reconfiguring all the data sending units to run a new electronic management system such as, Motec, Haltech, Electromotive, or the like. Then of course spend some time tuning the thing. While you're at it, change the intake to a nice ITB arrangement. 348 heads flow very well on their own and will very minimal porting they flow even better. 400bhp+ is not at all unreasonable with such an arrangement but it is indeed a rather larger undertaking.
It will pass ........ if you go down from 4.5 to ernie's 4.26 ratio on the dyno .......... you should see some very nice numbers .......... and if the RPM matches factory spec (as ernie's charts now do), that will be even better! I have been researching piggy backs for that 348 T-Project we all talked about over lunch on Dyno Day ......there are some good options out there. Let me know when you want to run your SS .......... so we can meet up there ...... I will be capturing baseline numbers for future 5.2 mods. Since I will be running a stock muffler for baseline, it can also serve as a 355 reference for all of your 348 'dyno day' runs. I do like the idea of a 79mm crank ......... but that would be down the road a bit ......... .
No, your gearbox has a DIFFERENT ratio than mine. If I'm not mistaken the Series Speciale cars got the early Spider gear ratios. Your gearbox number is not the same as mine, there for your final ratio is NOT the same. You need to solidify what gearing you have in your tranny. I'm gonna say that your car probably has the 4.429 ratio??? But the only way to know for sure is to get the gearbox numbers and the ratios for that number box. The wrong ratio also explains why Jeff's car showed his peak torque at 4000rpm. Jeff's ratios is actually 4.757, because he has a post '94 Spider. If he does another pull he will make the same horse power, but his torque figures and rpm band will change, just like mine did. You need to make sure you do your pull with the correct ratio.
Bozo, where did you get the ratio for Jeff's car? That's what I calculated mine might be is I used the "reputed" drop gear for the SS cars - 25/29. Can I do some runs at Church's with both input to see the difference? If the curve fits the car's rpm range then we'll go with it. Fuel cut off at 7750 rpm. Yep, we did this on the 358 race car and it was a huge undertaking - for Bruce, that is. Went to Motec from an Electromotive, I think, so some of the base work was already done.
Jeff's car is a '95, and I got that ratio from the technical manual for the US model '94 348 Spiders, yuh doofus. I called Jeff and asked him to check his gearbox to see what number his is stamped.
Hi guys, what a chance !!!!! I own a F 355 Challenge and the car gets several modifications at the moment. The work should be finished next week, then we can see the results. My modifications: Race port work on the heads Lighter valves with stiffer springs hydraulic valve lifter changed into mechanical valve lifter High compression ratio pistons (race pistons) 360 crank Race headers and exhaust without a bypass Motec ecu and a 10000rpm rev limit changed race cams Hi flow injectors Hi flow fuel pump Maps sensors instead of mafs Ported/bigger throttle bodies Light weight flywheel and race clutch Estimated about 450HP at the crank.
Nice modification list there. I'd say 450bhp at the crank is a conservative estimate. 470 bhp would not surprise me from this build it you're revving it that high
I just got off the phone with Jeff (darkangel) and the gear box in his '95 Spider is 155989. This means that his car and Vince's Series Speciale both have a 4th gear final drive ratio of 4.757.
Wow! That's great. At a -15% drive train loss = 467 at the crank -18% = 485 at the crank What kind of dyno was that on, and where are the graphs man, the graphs!
