I believe they will, I asked that question once before and the believe the answer came back yes....but there might be an oil return in the wrong spot or something like that.
They do seem to fit. The bosses for the tensioners and cover studs would have to be drilled and tapped but it's all there. I have a 348 in for an engine out service and have been comparing it to QV heads. Even the heater hose port is there. The cams interchange except for 1mm differance in the pully hub. When I compare head gaskets I'll know for sure.
Oh you're too funny, sure the mechanics of it could be done with a bit of effort but the ECU programming and controls would be a real PITA! no thank you. I am aware of the BMW 'vanos' and it's workings, problem is it's still limited in it's range, and modifications to cams cause all kinds of problems. it would have to be designed to handle a 'set' range beyond that the customer is kinda of SOL.
It seems like way more bother than it's worth to me. Im pretty sure that bolting on 348 heads would be good for at least 10% hp bump, but Im not sure about more than that without doing work on them. I knew the intake valve was bigger and the intake port opened up a bit making me thing it might be a different casting ..but if all the 308/328 bosses are there and unused, its most likely the same casting. That means there probably isnt any more metal; to work with in the port walls. So I guess if you can get a good set of 348 heads and bolt them on, youve got a 10%-15%. If you want any more than that, its probably just as good to start with 308 or 328 heads, youve got to do all the same work and you save the cost of the new heads. If anybody has a 348 head available, Im sure Vic would be willing to though it on the flow bench and baseline it so we know.
Will larger seats have to be installed to use 32mm valves? It looks like stock QV seats have 31.5mm OD If you decide 348 is good after market valves are available for half OEM. CR
hey guys, my offer still stands. redesign the head to work across all 308~348 engines with new ports and valve geometry. the biggest cost is the engineering and CAD dwgs. I'd help with that for free! as long you all don't want it in 4weeks from there it's casting and machining cost which isn't really that bad. a mid year project maybe?
Wow, that would be a big project. It's one thing on a pushrod engine, but on an overhead cam, it's twice the project. The 4v heads are pretty good. With a little clean-up the intakes ports are the higher velocity Vic has ever had on the flow bench, which includes most aftermarket heads. The flow will come up enough to feed the engine to 7700, I think they can be made to work to 8500-9000. I don't know that there would really be a pay-off for new heads. The 2v heads I'm not so sure about because I haven't seent he flow numbers yet. The valve are big enough, but the ports are a bit odd by modern standards, but they can definately be made much better and if 4v heads can be retro fitted if needed, so again, I'm not sure about a new head.
You are right, 31.5mm seats 348 valves are too small, no doubt about that. Changing seats isn't a big deal, so I think while the head is off, it's worth getting the flow up to where is should be.
here's a little update. 32mm valves do increase the peak flow, but no where near as much as the area increase, causing a pretty significant loss of velocity. 31mm seems to be the limit, at least with a 308 bore. Pricing on the vavles is still higher than Vic thinks it should be and he's looking for the quanity price breaks now to see how many would need to be ordered.
Do you have a price on the 348 valves? A 31 is 3% more than a 30.5 and can be had with an oversize stem to avoid changing guides, but maybe just sticking with 30.5 makes more financial sense? Also, do you have a list of the QV cams Web and megacycle have on file? That would be a great bit of info to add to the thread. If the flow comes up short with valves and porting, the cams are the next place to look .I dont think it will come up short, but its always best to have options.
To me it sounds like the 30.5 is the way to go. What's the flow difference between it and a stock valve? For one reason, it will be easy just to say 'it has 348 valves' when briefing someone and gives a better level of long term supportability if needed. What do you guys think?
Vic is testing 31.5mm today he says. Also a custom vavle give the option to make a bit more room for high lift cams and the option to make the valve head shape optimal. If anybody has a couple 348 valves, or can point me to a place with a good price, I'll get a couple to test.
Jeff at partsource. www.ferrariparts.com This is where we get the aftermarket 348 valves. Jeff goes to cavalino every year so he is probably closed untill monday 1/29.
If he Vic is having significant velocity loss at 32 mm, I'd prefer backing off a bit. In my NA carburetted application, velocity seemingly would be much more sensitive than in an FI situation - and peak flows are not as important as whole range flow and velocities in my use. I'll be interested in seeing the numbers to decide, of course, but based on that loss of velocity input, 30.5mm sounds pretty good if the velocities are still high. From the sheer physics of the entire track should uniform in narrowing. Using my 40mm carb throat as a start, it leaves little leeway as it ramps down to 32, also remembering I will have a 34 or 36mm venturi. this again suggests a more modest and discretionary 30.5mm valve. In example of the Bernecker car, stock valve sizes were used with a P/P and he had "315 hp at the wheels". I thought we had the 348 valve flow numbers? This is all pretty amazing, I'll say. If I am looking at a 25% increase, assuming my induction can keep up, with continued good streetable response, that likewise puts me at 300 hp at the wheels if it directly and linearly translates, while maintaining high flow velocities which directly affect response and engine friendliness on the street. That 300 rwhp would be **quite sufficient** for my goal. If you follow Bernecker's example and accept his numbers, the stock intakes are good with just p/p. I keep cautioning myself to remember what the goal is for me, which is somewhat more tempered than best peak flow. There are a lot of interplaying considerations on this, and it is fun balancing them all. I'll wait for all the numbers, but I think the picture is becoming more clear. I hope this works.
What Vic said he found is that every time he increased the valve size, the flow went up by at least so much as the valve area increase, so velocity was equal or better. That is until he went from 31mm to 32mm, it should have been a 6% increase, but it was only 2% or so, so velocity dropped 4% and Vic doesn’t like that. It would still be really good and one of the best heads he’s ever done, but he’s got it in his head that it will be the best head he’s ever done, so no 4% velocity drops aloud. The plan is to now test 31,5mm and then maybe 31.75mm and 31.25mm to find out exactly where the problem begins and get the most out of the head that can be gotten. A 3.0 liter engine at 7700 rpm wants about 120ish cfm and a 3.2 wants more like 128, so Vic wants to get as close to the 120 number as possible without sacrificing any velocity which would hurt the low end performance. Just for reference, the flow numbers down at low lifts are exceeding what my engine simulation software predicts for a ported race head and are doing it using about a 20% smaller valve then the software assumes….the numbers are good. The 30.5mm valve (a test valve, not an actual 348 valve) flowed 101 at .300 lift and something like 105 at .350 (I have to check my notes), so it’s not 120. The low lift flow numbers are about double stock, so that helps a lot and makes the peak number less important, I think if we can get the heads to .110 at .350 lift, it will be really good. That should make the hp peak move up to about 7500 rpm or so with the torque peak right about stock and everyone will be really happy. Sticking with a 30.5mm valve is a fine option, but it will leave about 3-8% sitting on the table depending what the max valve size ends up. 3% is about 10hp, 8% is closer to 25hp. It just feels wrong to leave hp on the table, but I think it’s best to wait and see the final flow number before making any decisions. It would be nice to have an OEM valve for ease of replacement, but I don’t know if it’s 25 hp nice (50 to me at 15 psi boost).
I forgot this part. The seat ID is smaller than the valve by at least 2mm, often 4mm, so with a 31mm valve the seat ID will be no bigger than 29mm. Also, it's ok if the venturi is smaller than you'd like with the taper math, it will be a flow restriction, but that is what makes the carb work, the only way around it is EFI, and that is not where you want to be for simplicity. There is a price to be paid for everything even simplicity and in this case you will pay with a flow loss at the carb, it shouldn't be too bad though. You will also probably find that once the heads are done, the 36mm venturi will work better than the 34 does now, probably more like the 32 does now. There will be a lot more vacuum at the venturi without the pressure drop through the port. You will also most likely have to jet down quite a bit to deal with the extra vacuum, Vic will have a better idea of where to start than I do, but I'm guessing 10-15% smaller jets. I guess we could make you specail 38mm venturis too....every little bit helps
Cool. I think the 34 or 36s will be fine actually for what I want. More vacuum - better drivability. I do agree on the jet changes if the vacuum and therefore velocity are improved, but only at the idles and air corrections. While not getting into a jetting discussion, it is at the ends of the flow bands where the flow will need be adjusted, i.e. the idles for below 2800 and the A/C for above 6000. And as said before, perhaps now the overly rich stock DCNF accellerator pumps will finally have their day if the velocity is as good as predicted. I'm hopeful. Thanks rt
Vic is still putting together some graphs and pricing, but things are looking good with flow and velocity up dramatically across the board. Final hp will depend on cams, with more lift beong better, but with stock cams there should be hp/torque gain from idle to redline with it picking up about 20% up top. Not bad. With individual throttlebodies and .400ish lift cams, 280/300rwhp looks right....which is 600ish rwhp once I add the boost The pricing should be available by tomorrow, I'll post it when I have it. Vic will be ordering 64 custom valves, so if you think you want in, you might want to think about being ready to getting a deposit out or you will need to wait for the next valve order. Also, Vic is going to see if he can work a deal with WebCam on a cam grind that will work well with the heads and the street. Again, I'll post numbers when they are available. The exhasut still needs to be looked at, but it doesn't need much, the stock flow was way too high compared to the intake, so it might be as simple as radius valve seats. Image Unavailable, Please Login
I'll add this, when you plug in the new flow numbers with the valve lift profile for the stock cams, it looks like exactly a 30% increase in air flow into the engine. nice.
That IS nice! It'll be interesting, for me at least, to see what improvements can be made to a 2 valve head.
Have looked at the numbers in relation to a 3.2 liter. The 3.2 head and valves are exactly the same as a 3.0qv, Ferrari compensating by increasing the lift to about .348 in the 3.2 liter from .303 in the 3.0qv. Currently, the car has Webers, which with the stock cam produce on the best day around 240 rwhp on the dyno as compared to a stock 214 rwhp for a standard US 3.2 liter. This increase of ~26 rwhp, or 12%, was just from relieving the FI manifold restriction. I later put higher lift intake cams with .368 lift and had no hp increase - this is also supported by Kermits and Vic's numbers that the stock head is essentially max flowed before .350 lift. So if the head is my current restriction, the higher lift cam will come into play with with the ported head, and this is what we see. So the current cam will essentially almost reach the max flow between 350 and 400. While most of the story is the increase in flow at the lower valve lifts, it's hard to predict just how much over the 240 rwhp it will go in my 3.2 liter application. If you use the 30% number of increase in total flow over the stock head with FI on the original 3.0 qv (which typically makes 200 rwhp), that suggests the new normally aspirated setup may produce 259 rwhp, or 312 at the flywheel in a 3.0 (assuming near linear relationship). Vic, who has all of my numbers, suggested that I would see a 15 - 20 % increase in power. If you use the 15% number as a conservative , that is a rwhp of 276 rwhp, or 332 at the flywheel, which is mind boggling. And since you asked, if even as much as 18% improvement would be 283 rwhp, or 341 flywheel hp. I'm hopeful.
As this thing gets closer, wanted to re-verify adequacy of the 34mm or 36mm venturi in a Weber to feed the ported head on a 400cc cylinder. In the 1966 Maserati Ghibli, a 34mm venturi was used to feed a 590cc cylinder on a V-8 producing 330 hp and 290 ft-lbs of torque. Interestingly, it used a 60 idle, 140 main and 180 A/C jet. Hopefully between the 34 and 36mm venturis it will be ok.
