I have to admit up front that I do not own a Gen 3 car, but I've followed this forum for it's technical knowledge of turbo charging and I'm hoping you can help me out. I'm looking to do a twin turbo in a mid-engined car that I've owned and worked on for 16 years now.

The car weighs about 2,900 lbs. and has a pretty healthy solid roller 359ci SBC. The engine is built to rev to 9,100 rpm. Here a some of the components used:

37 pound Bryant crank w/honda journals
Titanium valves, retainers and locks
43 gram titanium wrist pins
Shaft mounted rockers
Lightweight Carrillo rods
Jesel timing belt
Rev Kit
50mm Roller cam bearings
World Motown Block
Bore: 4.200 - Stroke: 3.265
Ported RHS 220cc heads (Flows 312cfm @ .700)
Ported Edelbrock Victor Jr. for EFI
Accel DFI running sequential w/ 48lb injectors
MSD crank trigger
Snow Water/Meth injection system

I'm looking to do a set up on the inexpensive side as money is really tight right now. Plus space is a real issue for packaging in this car. That being said, I don't have any room for mounting or routing for intercoolers. Also, I'd prefer to use internally waste-gated turbos because of the way the exhaust is setup. My goal (hope) would be 450 crank HP @ 5 or 6 pounds, then 650 crank HP @ 12 pounds of boost using a dual stage boost controller. I also love RPM, so the higher in the range it could continue to make power the better (without a nagging amount of lag).

A few key questions I need answers or advice on would be:

1. Which turbo charger could fit this criteria? I'm hoping to use this one, but am nervous the verdict will be that the turbine A/R is too large.

http://www.ebay.com/itm/400347751649...84.m1438.l2648


or this one, but I cannot figure out some of the critical specs like turbine A/R, so it may be too small?

http://www.ebay.com/itm/271100458623...84.m1438.l2649


2. My combo used to be 331ci using a 40 pound 3.00" stroke crank and 4.185 bore. It was fun revving the thing to 9k. It had zero torque, but made a ton up top. I kept the crank in hopes of using it when I went twin turbos. Would this crank be at all advantages for spooling over the (already pretty short) 3.265 stroke I'm currently running?

3. My block is maxed out at 4.200 with a .250 wall thickness (according to World Products) is this wall thickness sufficient to run 12 pounds of boost?

4. Will spraying the water meth alone allow for a reliable 12 pounds of boost?

5. What compression ratio can I get away with? Would 9:1 be pushing it for my build given the lack of intercoolers?

6. Any advice on a cam grind or some key numbers for the cam would be helpful.


I'll be grateful for any and all advice, questions, or comments.

 

I am giving you this advice because I don't want to see you making any mistakes in the long run. First off, your going to get people saying use this turbo, and use that turbo, or this turbo is good for this amount of horsepower, or this turbo is good for that amount of horsepower, and then you will wind up chasing your tail with with never ending problems while getting unending excuses like; well it worked for this guy, doesn't make sense, etc. Bottom line, invest in a quality turbo charger(s), quality wastegate(s), a quality set of injectors, and dial in your tune with that DFI. Methanol helps tremendously, and 9:1 compression is actually ideal. Switch to E85 later without changing anything other than the injectors and you can go even higher in your static compression without even running Methanol and not even worry about it. Remember, 12-psi means so many different things when it comes to particular turbo chargers, and the quality ones will flow way more at 10-psi than a cheaper ebay turbo at much higher, and that is a tremendous difference in boost pressure, lemme tell ya (not to mention heat, which equals potential detonation). I went with a Bullseye Batmowheel Turbo and will never go back (especially if I planned on spinning it all the way to 9100-RPM), but you don't have to go that route if you don't want to, as there are great turbo's to choose from. Do the ebay's turbo work, sure they do, but will you make more power at lower boost pressure with a better turbo, absolutely! The question is, would you rather pay now, or later? By the way, you can get away with just one turbo charger for your horsepower goals, especially if the packaging in your mid engine ride is tight.

Edit: Good luck, and by the way welcome aboard...

 

if ur stuck on ebay turbos , a pair of ebay gt3582's with the t4 ptrim turbines would be a good place to start specially with ur modest power goals

i run a pair of twin gt3076's on my car and they are good for around 1,100max hp for the pair, unfortunaly u cant buy these with the larger turbine


u can how ever get a pair of t04b's with the large 1.05 t4 housing which would like the high rpms but run out of air somewere around 650-700 crank hp

 

Something does not compute here... all these exotic cup take off parts for the long block and then expecting needin turbos to get 450 crank HP when this thing is supposed to rev to 9100 rpm???

 

This motor should beable to make 600-650 hp all motor by 8000-8500 rpms

You need to reevaluate the goals here.

 

I should clarify a few things so this don't come off appearing more whacky than this probably looks.

The motor was designed to withstand shifts at 9,100 rpm. But please know, I'm not trying to shift a turbo motor that high. I'm hoping to still be making decent power to 7,500 without it nosing over. I admit to shifting this high when I had the 3" stroke combo (mostly for thrills).

The other point I should have made is that I've grown tired of the race car cam'd motor on the street. It was a cool idea for years, but for the street it just doesn't work for me anymore. No torque down low, but all upper end power. Even on the highway I can't normally get to 4th gear because the motor can't just cruise at 2,700 rpm. I want a combination that's streetable. Meaning decent torque down low and high RPM power, but not "9,100rpm high".

As far as probably being at 650hp already, I don't believe that to be the case. I haven't dyno'd the car, but guess it's more like 525 crank hp. I have a 150 shot on top of that. I don't have enough cylinder head to make that sort of power. Hard to do with 23* heads and a pump gas friendly 11:1. But even if it were already there I would elect to do this same build. Because, as you know, 650 N/A HP from a small block and 650 HP from a turbo motor are two entirely different things. One would be a race car and one is a street car.

I realize my power goals are lower than most, but keep in mind I do not want to intercool, plus my clutch, transaxle and cooling system are only really good to 650 - 700hp. And upgrading them is something I don't care to get into at this point.

If I can get away with a smaller turbo, possibly a T3/T4 or T3, I'd be fine with that, but I thought by reading a fair amount of posts here that T4 housing was the only way to not strangle the motor up top.

 

Ok that makes more sense. For the record i have seen 600's hp from 300-315 cfm heads could be done especially with rpm with those cubes but besides that.... Turbo is better for street

Your build is simple. 650 hp a t3/t4 hybrid could work for twins but i would just do a simple small a/r t4 p trim size turbo with around a 56-60mm compressor. Fit the heads better its gonna want to turn some rpm.

Could just throw in a hyd roller with matching springs to keep it simple. Or mild solid roller, street cam. Turn low 6000 rpm peak hp and shift mid upper 6k's. Would be fun

Get 60 lb or 72 lb injectors

 

I'm really hoping to run twins. I've never been a fan of a single on a V8. I was hoping to make peak power a little higher Orr. Is it possible to run less boost and larger or smaller turbos in order to change the power curve upward? I definitely want more usable torque down low, but was hoping not to be all done by 6,500rpm. I guess this could be fine as long as it's still pulling after mid 6k. I think I'd like to keep the solid roller setup because I know there will be times I want to wring it out. All of my other cars have redlines well past that. So I know I'd be hitting the redlimiter all the time out of habit. Do you have a spec recommendation for the T3/T4's?

And is there anything to running my old 3" crank? I was told back when they made it that it would love a turbo set up. And I should also make it known that I'm running 1 5/8" primary equal length headers. Will this be a problem at this sort of power? And lastly, is the internal waste gate a definite no-no, or can it be trusted in a build like this?

I'll start looking for new injectors.

Thanks again for all the advice.

 

Nothin wrong with rpm but if you want to turn that high you will have that racey idle cam that you dont really want and also lack of low end. Peak hp higher than 6500 will likely have peak torque in the 5000's rpm range and not much below 3000. Gear will make up for that but general driving may be abit soft.

If you want more rpm say 7000 rpm, you will need like 6 psi to make your goal. More rpm is more hp and less boost. You need to size the compressor for that, as that is a different operating map compared to a low rpm motor. Your bottom end is fine and sounds very stout. 650 hp on boost is walk in the park. May want to consider a higher hp goal with that many rpm. Just because your bottom end can handle 9000, doesnt mean its a good idea. That kind of valvetrain to support over 8k rpm is very serious and not sure how durable that will be in street duty. Very expensive too. Race parts on the street dont always work out but can be done. Look at drag week guys. They live thru more abuse than most street motors

 

http://www.speedtalk.com/forum/viewt...hp?f=1&t=33764

Sounds awfully familiar