308 QV head porting

Clive
In another turbo thread, there is a kit being developed with a very clean installation of a small single turbo that uses the existing K-jet injection that might fit your development cost better and still give 350 hp or so. Very simple with few parts, appears well thought out and very clean. Check out the photos:
http://ferrarichat.com/forum/showthread.php?t=131709

best

 

Thanks for that, I have posted a question on the turbo thread asking how much they would sell kits for. I may as well start looking into the power issues now.

One of the things I like about Mark's old unit is that it is tried and tested and I respect Mark in that he seemed to know what he is talking about (and doing).

 

BTW
Have we any rough idea what the normally aspirated option as outlined in this thread would run to in terms of dollars?

 

getting technical now, the flow bench tests a steady state flow at 10" or 28" of water. now as we know the engine may for a split second achive that flow but due to dynamics of the wave it's far more active. compression, reversion etc...

okay so with that here's what i'm trying to figure, and maybe there isn't a calculation for it. we can measure the steady state, we can calc the optimum CFM of any given engine. but the two don't correlate to one another. can it be done? can we say, calc that a 3.0l V8 uses 394 CFM based upon 100% fill and no loss and cross reference it over to the flow of the head? atmospheric is 28" well technicaly its 29.9. so taking the stock flow number of 87.7 we'd multiply it by 1.67 to get 146.46 CFM. and that's one cylinder. multiply it by 8 and were past the CFM of the engine at 1,171.68 CFM. so that doesn't work since the valve isn't at peak for 1 minute.

maybe this will work, take the duration of the cam in degrees, having a cam card would be alot easier and probably needed. plot the time value for each event and note lift vs flow and that should give a fairly average flow value for the timing event on the cam. the total CFM there would give a rough est. on Ev too. from that one could then calc a bit better on the engine. now it still doesn't handle the acustics of the exhaust event or the piston.

the only way i could think of testing it would be to build an engine test stand that uses an electric motor to spin the engine while measuring the CFM at specific rpm's. it would take into account the wave acustics of the piston and chambers.

Amazing how much science is in an engine huh? this is why i get frustratred with the 'bolt on' guys and thier HP claims. oh well, back to the numbers crunching

 

Come on stock, now you’re making it all hard…..

You basically hit on the head a couple time though. This one will blow you’re your mind a bit a naturally aspirated engine can get to a volumetric efficiency of about 138-140. That is what tuned intake, exhaust, and velocity are all about.

A lot of the numbers are empirical, basically it’s all ratios based on known good set-ups. The software basically uses best-fit equations derived from the empirical data. Getting to your questions, a 3.0 litrer red-ling at 7700 wants the intake flow to be about 120 cfm at 10” water. If you raise the redline to 9000, then the heads need to flow about 140. Or maybe make it a 3.5 at 7700 and the number is about …140.

I’m pushing Vic to get me at least 110 from my heads, more than that and the seats would need to be replaced and the port wall would get pretty thin. Hopefully the final number will be in today, but the 110 should yield a naturally aspirated 330-335 hp at 7700.

I had a good look at the 2v head, to port and valve are pretty big….although the port actually tapers backwards, that needs to get fixed. The valve is actually too big, but since you really can’t get a .500 lift cam in, the extra diameter helps. The problem is velocity will be reduce, but maybe careful head shape design can help that.

The math way to get at is to measure the cam, plug in the flow curve, plug in the rpm. You still need to know VE, 110-125 is reasonable for a good street engine, running an air filter and muffler.

You’re a little mixed up on the air pressure thing. Atmosphere is 29” is Hg, some 33 feet of water. 10” H2o is another empirical number, it’s the manifold vacuum a general-purpose race engine generates. 28” is more typical in a stock large displacement engine. Some guys think that the higher vacuum (28”) helps find the problems, others (including me) think it creates problems by producing unrealistic velocities in the port.

The line I heard once and will never forget “I don’t care if you’re Jesus Christ himself, without air, you aren’t going to make hp”.

 

Are you refering to the choke point just above the valve stem? I noticed it looked like the port tapers down gradually from the carb, then opens up in the valve pocket area. Is this what your referencing? I also see on mine, that the carb bore being 40mm, is much smaller than the manifold port, which was like 47mm or some such. Seems that correcting the manifold to match the carb bore, and matching it to the head would go a long way toward making it flow better.

I have finally begun work building a flow bench. This should hopefully become interesting. Wil sent me a single cylinder head section from a two valve, and I would like to really see whats the easiest way to alter the flow. I plan to get some base line numbers off my two other stock heads, plus the single head chunk, then simply match the ports by eyeball and retest. I really believe port matching will make the greatest difference, but ya'll talked me into checking the flow so thats where i'll start.

 

By current thinking, the intake track cross-sectional area should be smallest at the valve seat and get steadily larger all the out. There are a couple reasons for that. The first is that air HATES to go from small to large flow area, there is a significant flow energy loss that occurs. You have no options entering the cylinder, but that should be the only place in the intake track it happens whenever possible. The reason for the taper working, the best I can figure, is that there is energy loss to friction any time air is moving, the taper compensates to minimize the friction losses.

Both the 2v and 4v heads have a similar problem in that the the opening at the manifold flange is just too small. On the 2v head, it appears to be the smallest cross-section in the port, where it should be the largest. That type of port design was very common up through the 80s really, but it turns out to be not the best. Ferrari fixed it on the 348 head, but 308/328 heads need some help in that area.

I think the next problem is at or near the valve stem, where you are looking at. I think the about the beast will be to effectively reducing the seat are a bit with a custom valve, the use that are to back out the port tapering larger (area, not shape is important, the port can get narrower, if it gets taller) the whole way out, preferably at 4 degrees.

Up at the carb end, be careful there. The mis-match between the carb an intake in not ideal, but filling in the intake will probably do more harm than good. You can use oil-base modeling clay to play with it on the flow bench. Also, under no circumstances would you want to radius the bottom of the carb to blend into the port, that will almost certainly create flow separation and do a lot of harm. Air doesn’t seem to mind going from small to big that much if there is a nice sharp corner…a 52 or 55mm throttle body on a tapered runner would make it happier, but since that is probably not part of the plan, leaving the edge sharp will be the best you can do.


Good Luck!

 

Found this in an older thread about Jens Bernecker's fabulous 328 GTB/C which has a ported and polished 328 engine with EFI. Although he may mis-speak a bit I think comparing his "axle hp" to the factory flywheel numbers, his results are impressive. It's amazing to read the entire first post describing the entire car.

If this opening up the intake flow, adding a cam and porting and polishing even comes close to producing his "315 hp at the axle", well.... that's around 370 at the flywheel if that is what he means. Even 315 at the flywheel would be pretty amazing. Here's the thread on a truly fabulous car:

http://ferrarichat.com/forum/showthread.php?t=93579&page=3&highlight=roof+328+track

 

I think 370 at the crank for a street 328 is very possible, but will require higher lift cams, maybe a bit more rpm....and here's the bad part, about 50mm throttlebodies. The 40mm carbs with 36mm venturis would probably have to go to get you much above 300 crank hp (you'll know for sure once they are on the flow bench)

 

I checked into this when I first went to Webers. According to Pierce manifolds, a 300 hp engine requires a 33.5 mm venturi. Tate at Carobu has reassured me they have actually dyno'd several engines with 320+ hp with 34mm venturis. I think my somewhat more "modest" goal of 320 to 330 hp should be do-able with 34 or 36mm venturis - They are super easy to swap, so will dyno with both as well as road testing with the LM-1 Air/Fuel meter tuning response. Perhaps those super rich Weber stock accel pumps will finally come in handy!

With the current engine at 243 rwhp (approx 290 flywheel), swapping from 34mm to 36mm venturis did not make a max hp difference (but did in drivability), thereby making me think I am now maxing out the head flow, and is consistant with the Pierce and Carobu experience.

It would be very interesting to see the dyno graph on that engine to look at peak and torque curve. As I have said before, for me torque curve characteristics are more a driver than max hp.

In theory and based on how it drives now, with increased head flow the already improved response and drivability should become even better if Vic is able to keep the velocity up. As well, I think a 330 hp/270 ft-lb flat torque curve engine would be reliable and about match or max the other components (clutch, gear ratios, tires, etc) -- which is the hopefully achievable goal.

Should be exciting if this all works!

 

I am also working on porting my QV heads using 348 intake valves. It seems however that waiting for you final valve sizing is paramount. I have heard claims that a good 5 angle valve grind is worth 8%.

Currantly I have 45mm dcoe throttlebodies on delron intake manifolds with a Tec2 for engine managment. The dyno showed 252 at the wheels on a euro with 40k miles.

Could I expect to get an additional 11% also? That would be amazing!!

What if you also added 11:1 pistons and High duration cams turning 9k rpm?


http://ferrarichat.com/forum/showthread.php?t=116011

 

Great work on your qv, as we said before. Hopefully will be able to share some numbers from Vic in a couple of days. While I do like the idea of the 30.5mm 348 intake valves as using a "standard" OEM part, it'll be interesting to see if the 32mm valves add that much more. At least in my installation, I want to stay using as much OEM as possible for ease of support - but will happily go to the 32mm valves if it's that big a difference.

OBTW, what did you use as an exhaust?

best
rt

 

It looks great and 252rwph is a great result. It seems high, what brand dyno was that on?

Have you got a flow bench you're working with?

120 cfm will feed the engine to 7700 and make about 330 hp, or 270 rwhp give or take. If it you want it power up to 9000, it will need to flow about 140 cfm (at 10" h2o) and should make 380-400, but will need a bit more duration and high compression pistons. I'm not sure if the 308 heads can be opened up enough to do that, maybe...or maybe 348 head?

 

The exhaust seemed good compared to the intake so the plan was to keep the stock valves with a little clean up and polish.




Do you know any thing about 348 cams? They seem to fit and have the same offsets to the pully. They also seem to have .060 more lift, can't tell about duration.

CR

 

I trust dynojet numbers more than any other dyno, it must be right.

If the shop your working with isn't giving you a great deal, I'd recommend going with theshop I’m using since Vic’s spent a lot of time playing with the scrap head so there will be no mistakes on the real heads…small 4v ports act very different from big 2v ports.

If you decide to stay with the shop your at, do you want in on the valve order? Vic will be ordering custom valves once we decide on the diameter, the more valves, the cheaper they are. The plan is to order the stems .001” oversize so the guides can be reamed and don’t need to be replaced. They may not be big enough if you are shooting for 9000 rpm though.

 

I am interested in the valves and having Vic do the work. Have you looked into using motorcycle valves they have a large selection of 7mm stems?

Do you know anything about cam profiles? I have found that megacycle and web have more than a few QV profiles on file. I know very little but it seems to me that duration is of most importance on high rpm engines. Most of the grinds I've seen have a .415/.435. lift and the highest duration is 292.

CR

 

I put in a set of longer duration higher lift cams from Web. Short story is that the head cannot take advantage of them, so here we are.
There is a thread on performance cam regrinds and the numbers.

http://www.ferrarichat.com/forum/showthread.php?t=2788&highlight=performance+cam+regrinding

best
rt

 

upon re-reading the cam thread, we had talked about seperate airbox & plenums for each side to take advantage of the intake pulsing. As most know, every V-8 Ferrari since 89 has had separate plenums for each bank.
It does make sense as then the pulses are balanced. I had dual stressed aluminum airboxes fabricated and installed for each bank leading to cone filters at the side scoop, but have never had the opportunity to test.

As we are optimizing all components on the intake side, I'm wondering if we should flow the airbox. I may send the airboxes and carbs when I send the heads to vic - I'm especially interested in comparing the stock air horns with the short ones from Kermit that allow more area over the intake. The problem is that on the flow bench we won't see the harmonic effects of the pulsing and reversion.

 

Do you know what lift the 292 is at?

The thoughs on duration have changed quite a bit in the last 10-15 years. .415/.435 lift sounds right for these heads, but 292 degrees in a 4 v head is just crazy duration.

 

Just as an alternative - will 348 heads fit a 328 block?

 

not sure, but dang! I thought I worked late!

 

you know, just throwing this out there. due to recent projects, I've moved over to add in casting parts as needed. i found a good casting Co that specilizes in small run stuff. it's sand casting to keep cost down but still very good quality.

why not sit down and figure the problem areas and have a new head cast. the biggest factor will be the CAD design, I'll offer to handle that if you guys want to provide the input. don't see why we can't have new heads for a few grand in initial cost.

I'm pretty booked for the next few months though.

 

While not so much interested in designing heads, what's the likelihood of designing adjustable timing sprokets and chain tensioner to use an existing timing chain (BMW?) with an alloy cover with oil spray and sump return to replace the belts on a 3.0/3.2 qv? Perhaps the 348 belt cover as a guide?

 

WOW! now that's an interesting request. offhand i'd say it would be fairly expensive, around 5k or so to do initially. the one other issue is getting everything contained within the same plane. and adjusting the other bits in the way.

why a chain though? the new belt/pulleys i did are good for at least 75k miles.

i'll look into it, let you know what i can do.