Supercharged QV (take 3)-or is it a turbo?

Well it's just full of typos...but that's pretty normal for me....or did you mean the graph of the 1100 hp 308 engine

 

It would get better milage....but it would have to be a lot better to pay the extra cost. The hybrid cars claim great milage (which it turns out they don't deliver - the US gov is changin the test to fix that), but even with $10/gallon fuel the car would be in the junk yard before you ever got the money back.

I've honestly never understood why the people who live in Europe allow the government to put SOOO much tax on fuel, but I guess that thought belongs in the politics section

 

There is definitely merit to your plan. I’m already planning on 2 separate intake manifolds and I ordered the material to build them yesterday. Twin turbos is a good set-up particularly on a v-type engine…a little less efficient than one larger turbo, but that might be offset by getting more of the heat to the turbo with shorter pipes.

I need to think about moving the fuel tanks a bit….The space would be really nice, but where they are puts the fuel load on about the front/rear mass center so the car handles about the same at any fuel load. Putting it up front would make the front act different at different fuel loads. I don’t know if it would be significant though….I need to think on that one.

The first step has got to be to fix the heads though. If the number Kermit sent me are right, the intake flow is only 2/3 what it should be and there is no viable valve lift that maxes out the exhaust. I think I’m just going to go ahead and pull the engine and get the heads off….they need help. Since the heads will (hopefully) be changing A LOT, it doesn’t make sense for me to even try to spec the parts for the boost part…I just don’t know what engine I’m trying to match. I’ve got to fix the heads first, run the engine to get a baseline curve, then add the boost. That’s good though, because then there will be a nice data point for a QV with good heads for anyone thinking about working on their heads.

 

Playing with the sym again.... it thinks if I port the heads right and just put my old blower right back on, the boost will be down and I'll gain a couple hundred hp....I need to get the heads off for porting.
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As Fred says, porting can’t be done without a flow bench and many involve removing or adding material. It also can’t be done without a calculator. Just making the ports bigger will usually make more flow, but to make hp, the velocity of the air is as important as the quantity….it’s been my finding that most people, even people with flow benches, do more harm than good when they start “porting” a head. It’s really hard to do the job right.

I called T. Rutland today and they are looking for a scrap head for me. A scrap head to play with should save a lot of time because there is no need to be careful…if we grind too much, a little modeling clay will put it back. I’m pulling my engine and popping off the heads Saturday. Then I’m ready for a trip up to my buddy Vic’s to see what I’ve got.

I’ve done a few heads with good results, but Vic has done 100s with what I think are great results…so the plan is pretty much just to do as he says. His first look at the valve sizes and everything that I emailed him make him think 335-345hp NA with stock cams. To me the numbers looked like more lift would be better, but I haven’t talked to him about it yet…again I’ll probably just do as I’m told.

I sent Vic an email last night and asked if he had any idea about price…but he may want to wait until he sees everything.

I’m not sure about milling the head…I’ll look at the scrap head to see what could be done. Maybe the guys at Norwood would have an opinion on it? Compression is good, that I’m sure of… my first thought is you would want to change the pistons to get it, but there may be metal that can come off the head…I need to look at it.

 

I’ll know a lot more once I personally see the numbers on a flow bench, but if Kermit’s numbers are right, there is a lot more than 10 hp hiding there. Even if it turns out my number don’t agree with his values, the ratios of intake to exhaust are still way way off, just fixing that should gain 20+hp if I had to guess.

I’m going to try to set-up the flow bench for next weekend….so we’ll at least have the baseline confirmed and I should be able to spend at least ½ a day with Vic trying to make it better….now understand, getting the flow right on a new head that neither of us have messed with before could take 10 or 20 hours on the flow bench and includes port, valve, and combustion chamber iterations. Once everything is figured out, doing the rest the same goes pretty fast…maybe a couple hours per cylinder. It often means ordering custom valve shapes.

 

The engine's out. On to the heads.

 

The heads are off. Now the cleaning begins. Hopefully I'll get the junk/practice head this week and can get to the flow bench next week.

The feeling is the exhaust valves are fine to big as is, but the intakes are probably just too small...but we'll find out soon enough.

Anybody have any idea just how much lift can be put in a QV head? The math says 340ish hp on OEM cams, but the intake valve really wants to open almost .400 to get the full potential out of the engine.

 

That was my first thought too:
http://www.ferrarichat.com/forum/showthread.php?t=88373&highlight=355+heads

Then I got to tons of boost, which is what I started this thread with....now I'm back to do what I can with the OEM heads and use modest boost.

I'm still a bit concerned about what I see on the exhaust side of the stock head....the port is bigger than the intake which will make it really hard to get the exhaust flow to 80% of the intake flow while maintaining velocity. I may need to weld it in a bit - the 911 heas I did needed a ton of welding in the exhaust port, I made the port 33% smaller and got 66% more flow. I'm hoping I don't need to go that way here. Maybe larger intake valves and port to get the ratios better...maybe an extension on the header that fits into the port to reduce the size a bit. Or maybe, as you suggest, force fit a set of modern heads.

 

I thought I should share this...the other day I finaly got the time to conver the 83 lb/min the monster turbo I was thinking of to cfm....it turns out the blower I already have on the car flows about 81 lb/min. I would have spent a lot of time building exactly what I already have in a much harder way.

I need to get the heads fixed so I'm not losing pounds(or cfm) of air and fuel out the exhasut pipe. Looking at the head, the exhaust port exit is about 20% bigger then the intek inlet when it should be 20% smaller...that's going to be hard to fix.

 

Sometimes, just reducing the lift in the cams does help, it's not as goos as fixing the port, but it helps. The problem here is that the exhaust seat IDs are pretty much the right size...but the port exit area it 60% more than the seat area. Air just hates to go from small to big. When the angle in more than about 8 degrees, the flow separates from the wall and goes turbulent. That is what is happening in the QV exhaust port. It makes the port inefficient and causes the flow to go up with valve lift WAY past the point where valve lift should matter. I don’t see any choice but to close it up about 60%…I’m hoping to figure out some way to just put in an insert…welding in a port s*cks.

On the intake side on the other hand, the seat IDs and the port are probably too small. Vic is going to try to work some magic, but I’m pretty sure we’ll end-up increasing the seat ID and valve by 2-3mm…but if we do that, it will need more lift in the cam…like a 328 intake cam maybe.

Let me know...we'll get it straightened out.

 

Bigger combustion chamber mean new pistons to get the CR back up.

I'm thinking bigger valves will probably be required...I hope not...but probably

yeah, probably not a good idea.

A flow bench doen't tell the whole story, but when the number are what they are supposed to be, you almost always get the best hp. So, the exhaust won't be "restricted", it will be corrected. Bigger doesn't mean better most of the time.

 

I'm thinking that I don't think I trust development work that was done 20 years ago anymore. I know that a 3 liter race engine should make 420+ hp, 2 or 4 valve. In street trim with a stock redline 340 should be a good number, 380 should be good with an 8500 rpm redline. I might be wrong...time will tell.

 

Philip’s post got me thinking just a little bit…so this is a bit of a soapbox post…so stop reading now if you have weak stomach

It often seems to me that us ferrari types have been living in the ivory tower just a bit too long. We think the reason a street model ferrari can’t beat a 911 on the track is because the rules favor the porsche. We think the reason a ferrari can’t beat a vette in an endurance race is…oh I don’t know, the rules again. We think we need to hide from supras.. ..whatever you do, don’t race a supra. Why? Because there are supras out there with more hp than any TT 512TR ever had.

It seems nobody ever stops to actually ask why though. I think the answer might be engineering. The supra has a head that flows right…from the factory. A 308QV head is so bad I’m not even sure it can be fixed….it’s a ferrari and the head design is so bad it may not be salvageable. That is sad. Honda makes more hp/liter than ferrari, that is sad too. In college I has a suzuki switft that made as much hp/liter as as the ferrari of the day…an economy car for God’s sake. I’m hoping to get the same hp/liter I get out of my harely….think about that. A harley isn’t exactly known as a hp king in the world and I just wish my ferrari could be that good…sad. A small block chevy race engine makes 800 hp from 5.7 liters…that’s 140 hp/liter from a 2 valve pushrod engine…but a ferrari 308 4V overhead cam engine can only muster 126? Sad.

I honestly never thought that much about it because it’s a ferrari. I blamed the low hp of my car on it coming from the emissions era. I never really looked at the heads or flow when I built the engine because I was planning on boost anyway. But this project got me wondering about the supras. I spent a couple weeks my 308 barely makes 400…that made me think a bit.

OK I’m done ranting…back to the regularly schedule thread