Anybody have any updates on this project yet?
The engine is not yet finished. I'm looking for a set of 348 heads to adapt to the 308 block for this project. The 4 liter engine is being built for Mark Lewis. Nick is doing the 3.5 liter engines. Steve
Steve, I'm guessing you are having trouble getting enough flow? As I recall you already switched from the 2v to QV heads? You know the 348 heads are the same casting as the QV, so I don't think there is any more flow available from them. On a side note, Russ and I are working with Web cam to figure out just how much lift can be put into a QV head without needing to go to shim under bucket stuff....it's looking like somewhere int he .400-.450 range.
Mark sent me a pair of 2V heads for his 4 liter project. I worked out the porting, valve sizes, valve job on a junk head. I got it to flow right around 178 cfm on the intake side at .450" lift @ 28". That's about all they are good for without major surgery (cutting and welding). That is not enough air flow to get to the 400 hp + level that Mark is looking for on his 4 liter. That's more air flow out of the 2V head than you have gotten out of the 4V by the way. The reworked 2V heads should provide enough air for 360 flywheel horsepower. We saw 340 hp on Carobu's dyno with not much tuning and a pretty lousy stock style exhaust including mufflers bolted up on Nick's 3.5 liter engine. Horsepower peaked around 7,200 rpm with what I consider a streetable camshaft. I doubt much more camshaft timing would help the power and would surely kill the torque. Nick tells me the porting is different on the 348 head. I have not had my hands on one to know for sure. I do have one QV head here but have not had the time to flow it or do any work with the porting. I will tell you that the porting is a better design in the bowl area than the 2V but not as good as modern day 4V heads found on many production engines. You need to be careful with the lift vs. duration on the 4V heads because the followers are smaller in diameter than those on the 2V heads. You will need to run more duration to get over .400" lift than 220 degrees. You are going to find the nose of the cam will come to a sharp point and or run off the edge of the shim. Years ago I did development work on the old Fiat X 1/9 engines. Fiat sponsored us with a car and many parts to run in SCCA G Production class. That engine had the same exact lifter setup as the Ferrari 308 2v. We turned that engine 11,000 rpm with the stock shim over bucket lifters with .480" valve lift. I never had a shim come out. We went to the shim under design on the 2V head to save some weight more than anything else. The lighter valve train allows less spring tension and thus less wear. They are a pain to adjust because you have to take the cams out but working on these engines in the car is no fun any way you look at it. Steve
As best I can tell, ferrari did a much better job porting the 348 heads. On the QVs, the ports are actually reverse tapered, the smallest point in the port is the manifold flange area. On the 348 they opened that up and put in bigger valves. We decided to stick with the QV heads because we had them and the also though the extra metal would give more flexability with the port shape. Russ and I are both building small (3.0 and 3.2l) street engines and made the decision that we didn't need more than 120 cfm @10" (189ish at 28"?)and Russ in particular couldn't tolerate any reduction in port velocity trying to keep the bottom end up. For some reason when the port/valve were opened up enough to flow over about 112 (176@28?) the velocity started to drop, so we called it quits at 112 and are sticking with about stock duration instead of cutting it back to 205-210 like the original plan was to make up the difference. The finished valves are in and seem a bit better than the test valve, so the final numbers will be 114 (180?)I think and should work out just about right and that is throught the manifold, not just a bare head. If you recall, I commented on the other 4.0l thread that I thought your heads were just about exactly what I would like to have on a 3.0 engine. That's still what I'm going for. Everything seems good, but not good enough to feed a 4.0. It seemed like as the valve got bigger the cylinder walls were interfering with the flow and limited the size valve that would work to well under the planned size. Things may go better for you on the big bore engines. On the lobe the plan in a little more diabolical. The concept is to steepen the initial part of the ramps to more modern specs and actually round over the nose to control the bucket clearance.....the math says it can be done, but we'll see what happens.
114 cfm @ 10" equals 190 cfm @ 28" (correction factor is 1.67) so your flow is better than you thought it was. If that is the flow through the intake you can approach 400 hp with proper cam and an engine built to rev. Late model Honda heads, for instance, have larger valves and ports than found on these old Ferrari heads. Cylinder displacement is roughly the same. The Honda pulls off idle very well indeed considering the size of the ports. I wouldn't worry too much about the slight drop in port velocity you saw flowing @10" assuming the flow increased at least in proportion to the velocity drop. Depending on where the ring placement is on your pistons, you can grind a chamfer in the top of the sleeves adjacent to the intake valves to give some more breathing room around the valves. The large 89 mm bores we run unshroud the valves quite a bit as you mentioned. Even then, it looks like 33 mm is about as big as you can go on the intake valves without running into the spark plug hole. That's one of the things I want to look at on a 348 head. Ferrari a;sp may have moved the valves further apart or perhaps they went to a smaller plug. A friend of mine just got back from a private tour of the Ferrari factory. He told me that the heads are not available as parts. You can find heads for sale used in Italy but most are hot. Nick says there is a fellow making four valve replacement heads for the trouble prone 5 valve heads. They are way too expensive at $20K + for the pair bare. I used the fastest acceleration rate cam I could get in Nick's 3.5 liter. I got a list of profiles from Web that I could run some simulations on. The cams I chose worked well on the dyno for torque and power and idled down no problem. Nick should have his car on the street shortly to give me some feed back on driveablility. The car got badly damaged on the way back from Concorso Italiano last August when the tie straps broke in the trailer. Car is still in the body shop. Steve
That will teach me to look up the conversion factor and not just go from memory..... I think it's going to come out around 340 @8000 naturally aspirated. I really don't want to spin it any higher and since it's a blower motor anyway, it should still come out around 650-700 which is WQAY more than plenty for a street car. The veloncity is actually up almost 20% at all lifts from stock up to the 114 we're at now. It only starts to drop back down as we try to get more out of it, so we decided to call it a day. The flow definately continues to go up as you go up in valve size toward 33mm, but for our small engines on the street, we felt keeping the high velocity would be the better choice. The 348 heads changed almost nothing from the QV. The intake valve are 30.5mm, but on the same spacing, same spark plug size. As a bolt -on, they are ported better and have higher lift/duration cams, but if you are doing head work anyway, I see no advantage to starting with the 348 heads. The heads do turn up, another QV guy just picked up a set for something like $1000 I think he said....the valves were damaged from a broken belt on one of them I think he said, but they were complete with cams. For new heads, I think FoUK has them for the QV/328s, they bought all the old inventory....I don't know about 348 though. We talked to web about the prifiles they have but didn't find what we were looking for. I think they had one that would yeild .375/.380 lift or so, but we really wanted .400+. We're woring with them now to develop a new profile with a little different shape to try to get the extra lift and a wider nose to hold it open longer. The way the porting worked out the flow keeps going up to .400 lift and we want all the flow
