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

If anybody knows anything about specing the turbo, I'd love the input.

As I said in the other post I'm thinking Garrett GT42 right now...but it is a touch big I think.

 

I think the application really drives what mods are required and what the limits are. Road use is pretty easy on a car, roadrace use is not. On the street, you can add hp and nothing else if you choose because speed is limited. For road racing, changing hp, tires or suspension requires the brakes to be upgraded to handle the extra speed.

A couple years ago I spoke to Jim (I think) at Norwood who told me they had a couple 800hp 308s running at the track without problems and that the 308 trans parts look a lot like TR trans parts which are good to about 1100-1200 hp, but seem to have a ***igue life issue (at least in one f-chetters car) at 500 hp....but I don't know the extend of the mod. I've heard the stud axles hate slicks, but that is a Gs issue more than hp.

I'm probably not the best source of info for how to hook-up the car at the track, but hp isn't going to change the set-up an awful lot...tire widths and probably a bit more spring for the higher speed...but others could answer that better.

 

Thanks, I'll give them a call. I'm not sure what he's doing exactly, but based on the shape of the torque curve he's got a LOT more boost up top than on the bottom so I suspect it's a blow-through on the blower. My goal is a torque curve as close to flat as I can get it.

 

Good point. The stock cooling system works I guess if it's in perfect condition. I've installed a much larger aluminum radiator in my car because I was tired or worrying about sitting in traffic - driving it was fine.

 

The engine is currently supercharged and hits 22 psi at redline and doesn't seem to have any problems. It is fitted with a water/oil heat exchanger and a programable ECU that I set to pull the timing back to about 20 degrees at full boost.

What I'm looking to do now is take my boost curve (yellow line) and make it flat from idle to redline at about 20-25 psi....ok maybe a little more

I'm going to do some head and intake manifold work to try and get the torque to carry out a bit flatter after 5500. Even if I can't fix it, the turbos wastegate will keep the boost flat up top where the SC boost climbs due to the engines dropping VE.
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Yes. I corrected that as well as the way lean throttle on at the start of the graph.

I just realized that the place to find turbo on a 3 liter info is supra sites...tons of dyno graphs with different turbos....I've got some reading to do.

 

...and that is why god gave us excel

I don't think it will be that bad really. At low rpm, only the blower will actually be doing anything and above about 4500 only the turbo will be working. I;m a little concerned about the control scheme for the say 3000-4500 range, but I've got a couple ideas that I think will work depending on whether or not I use the CVT....the CVT will make a better system I think, but it will be a bit harder to get the controls right.

2 things here. I think the scope of the problem really depends on the system boost. You can get reasonably good low end from a 5 psi system, but a 25 psi system is another story...or it could be your idea of low-end and mine are a bit different. I've never seen a high boost turbo system deliver low-end performance that I find acceptable, which is why I've been sticking to superchargers.

On my engine or proposed system diagram?

It's not on the diagram because it didn't fit on the page and I was too lazy to shift everything to add it. On my current system there is a water/air unit built into the intake. I'm not sure yet what I'm going to do on the new system...I'd like to go with a simpler, more effective air/air but I'm not sure I can get enough space or cool air for it to work properly. I may need to stay with water/air, but it won't be inside the intake on the new system either way.

 

I'm just not sure what to do for intercoolers. The Aussie TT355 put them behind the rear wheels and I really liked that...but I'm not sure I have enough space on the 308 without taking the sides of the trunk...and I like the trunk, my canopy that is SOOOO nice at the autocross just fits side to side as it is.

.....although I guess I could put it on the wheel trailer I keep threatening to put behind it

I need to do a bit of measuring in the engine bay. I've pretty much settled on the basics now, so I can start figuring out where they go and that will give me a clue about the intercoolers. water/air untis big enough to do so good will fit behind the wheels...I might be able to do something using the side intakes. I thing the blower and the turbo will fit behind the engine...I need to measure and think on it a bit......

 

I went and did a bit of mearuring today.

There is really only one placd to put the supercharger that makes any sense, and that is behind/over the engine on the right side....unless I want to hydraulic drive it, and I don't think I do.

That leaves 2 places for the turbo. The one I'm pretty sure I need is pretty big, but will fit behind/over the engine on the left (show by a 10" duct I had) or under the car where the (empty) cat sits now. I like under the car, but I think that will mean I need a return pump for the oil....more parts.

The intercooler(s) depends on water/air or air/air and where I put the turbo. If the turbo goes under the car, I can fit a pretty good size water/air cooler behind the engine on the left. If the turbo is there, I can fit about a 12x12 unit behind the reqar wheel without going into the truck...that would give me 2 cores of about 12x7, which I think should be plenty. If I go into the truck, I can get a pair of 12x16 units, so 2 cores size 12x11 or so, I think that would be ok for air/air...I want hp, but I don't want to lose the trunk space. I need to think about it, air/air is lighter and simpler, but I do alread have the pump and radiators up front for a water/air and it space the trunk.
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Wil,
I think every project I've ever done was WAY more work than I realized up front if it makes you feel any better.

I'd still like to get out to see what you're building sometime, it sounds really cool.

There are 2 reasons I'm not planning to put the intercooler int he manifold this time. The main reason is that because I'm planning to run stupid amounts of boost and I want a really big cooler and it just wouldn't be possible to put it in the manifold. The second reason is thatI've got it in my head that part of the reason the QVs lose torque above 5500 is the design og the manifold. Ferrari changed the manifold design (and the dropping torque) on the 348 and has kept the 348 design on every engine after. I want to try that type manifold this time and it will take up all the space I have over the engine, so I'll have to put the intercooler somewhere else.