OK, I've played with turbos before on other cars and know my way around them but now I'm interested in what it would take for my '94 Formula to have a turbo setup for 600 RWHP that could take the rigors of road racing. I'll run the octane needed. That's not a problem. The road racing I have in mind typically is 20 lap sprint races, so that would be about 30-40 minutes of hard use at a time. As such, I would doubt my setup would be the same as a drag racer's or street car's.

Currently I'm going to run my car in NASA's American Iron through next year and build my AIX motor on the side. I have this thing for turbos and this year it takes at least 450 RWHP to be competitive in AIX. By '05 I'm sure it will take a good bit over 550 RWHP to be competitive so I'd like to have a little cushion.

Do any of you have an air to air intercooler setup with a single turbo out of 350 cid that makes near 600 RWHP? If you feel I need more cubic inches so I can keep the boost down I'm open to suggestions. I'm looking for a powerband of 3500-6500 that's very solid with potential to hit 7000 rpm if I don't want to upshift before the next corner.

Now, for a possibly tough question. How much weight would a typical LT1 single turbo setup with air to air intercooler add to my front end?

 

I thought to be able to race American Iron the power weight ratio should be 9.5lbs/rwhp. With 600rwhp u will be way lower than that (6.08lbs/Rwhp) if we assume a full weight Turbo LT1 race weight is 3650lbs.

I think u can make 600rwhp from a 350CID with race gas running 22-24psi. U should first built the motor for boost and set it at 9.1 C/R so u will have a good throttle response. If im going to built my motor from crank to heads i will just go with a 383 to increase TQ numbers. U know TQ helps aloooooot in winning races like this(going out of the hole fast).

Of course with 9.1C/R on pump gas u wont be able to push more than 12psi max. But with race gas such as 114octane and if u follow the rule that says every two points octane increase will allow u to run one more psi. So 114-93= 21 ........ 21/2= 10.5 psi more. So u can run 12psi+10.5 which will put u at 22.5psi. That should be enough to make the power u want.

Now we should look for a Turbo that can take around 23psi of abuse for a long time. I would go with two T3/T04E with 60 compresor housing and .86 turbine housing Twin turbos because it will give u instant power and no lag at all. They also have the power to hold boost up to 6500RPM. U dont want lag in road racing. One of the T3/T04E with that size could give u up to 650CFM. S having two will give u around 1300CFM which is more than enough.

Then u will need an intercooler good enough to cool that 1300CFM of air. Its going to be a huge one. I think this setup will increase ur car weight by 50lbs or so.

Sorry for the long write up, but u asked for it LOL. I hope everything works well for u. I road race too, but im going the SC route for smoother power band and less cost. The setup i mentioned above will be very smooth like N/A or SC car because of the choice of the turbo's, but its not going to be cheap. Good luck.

 

What is the discplacment max for the class you plan on running?
I would try to get the largest CID you can, which will allow you to run less boost for the hp level you wnat, which will improve spool times. You don't wanna be out on a road racing track and have to downshift or wait for the turbo to spool up.

Its tottally plausable to get 600rwhp from a single turbo 350.

To make sure everything lives....u gotta have a stout shortblock, but I am sure you know that already. I would get a single stage remote road racing oil pump, remote oil filter and cooler, and get a full legnth windage tray and crank scraper now that you have the oil pump outta the way. Use syn. oil also.

Turbo sizing can be done once you firgure out how much CID you cna run in your racing class. As for turbo specifics, I would ceramic coat the exhuast housing, and MAKE SURE to get a water cooled bearing housing. It is a must for hard driving on turbos. You don't want the oil coking (yes that is spelled right) in the bearing housing during a race. Also get a turbo timer for after races so when you leave your car you dont have hot oil and water staying in the bearing housing.
A good aftermarket intercooler should be fine, manufactuer choice is yours, if you have the bucks, get a Spearco, or a custom make Ron Davis Radiators one.
Exhaust....I think there a few single turbo application turbo headers for the LT1, but I am not positive. If you can, ceramic coat those also. Wastegates from Tial, or turbonetics are good ones, and BOV's from Tial or HKS.

I appologize if you already know this, just wanted to make sure
Weight question.....hmmmm I will guess anywhere from 40-80 lbs...but it depends on teh sizes of your intercooler, turbo and how much routing your gonna have to do.

Hope this helps
Hunter

 

Thanks for the replies.

In AIX there is no lbs/RWHP limit. There's just a minimum weight limit. It's AI that has a 9.5:1 lbs/RWHP limit.

There is no CID limit in AIX either. The engine is pretty much unlimited. I plan on getting my Firebird down to 2900 lbs. with a full tank of gas for the class. Right now it's about 3100 lbs. with full cage, etc. and still has a steel hood, glass windshield and rear window and stock k-member.

I see no cost reason to not go with at least a 383 CID small block for the class since it would cost me pretty much the same to build as strong of a 350 since I'm replacing the whole bottom end anyway.

The turbo engines I've played with before are 4 cylinders and V6s. Based on those engines I was guesstimating it would take about 15-18 psi of boost with a 383 engine to make 600 RWHP assuming good heads and induction system. It sounds like I may have been overestimating the potential. Over 20 psi of boost in a road racing application starts to worry me without a lot of knowledge on how to make it live.

Are there any kits that would have potential for 500-600 RWHP that would give me a good starting point of what is required? I'm also concerned about packaging the system efficiently since I have things like brake cooling ducts to worry about. Some of the kits I've seen seem to package components close enough I'm concerned about what impact they would have on my other components. The front bumper is gone so I have a good bit of room to package an air to air intercooler there and can open up the fascia for air flow to it and the radiator if needed (and I think it will be).

I'm not too concerned with some lag, mainly for traction reasons. Perhaps a twin turbo setup would be the best overall, but again packaging concerns and traction limits come into play. Starting in '04 AIX will be limited to 11" wide wheels which means I'll be running 315/35/17 Hoosiers. I have a T2R and the 315 Kumhos right now but am still at a very low 290 RWHP. No traction problems right now, but when I double the HP . . . ??

 

Twin Turbo's is not only good because u wont have lag, but it will give u a smoother and predictable power delivery which is good when u are on the limits on a turn.

 

this could be fun

personally, I'd rather start with a 98-02 Camaro because they are very aerodynamic and have a big grille that could be used to help with the intercooler. Oh yeah, they also have the alumium block LS1 which would offset some of the weight up front.

Since it's a race car, it won't have A/C, right? The factory location for the A/C's condenser might not be a bad place for the intercooler.

For the engine, I would do the opposite of what has been mentioned with the compression ratio. Run a little more compression with top of the line bottom end parts. Then run alcohol for the fuel and run all the boost you want. You might not even need an intercooler for this set-up. You'll want a fuel cell anyway, so build the entire fuel system for alcohol.

The only downside is the amount of fuel you'll need per run. It takes roughly twice as much alky by volume as it does gas to run. You'll have MORE than enough power to overcome the extra weight you'll need for the extra fuel. It might make coming out of the corners a bit tricky though

 

That is an intresting point, but as u said above how much fuel is needed to complete 20min run. For Example, my car with only 350rwhp needs half a tank of gas which is around 6.5 galons to complete 20min run. So bascially he will need to use all his gas tank and hope that 600rwhp wont drink it all before the 20mins are up or upgrade to a larger one (16 Galons tank).

 

I would reccomend more cubes and more head. something like a 406ci 18degree headed motor.

 

You haven't mentioned bduget, so I won't take that into account at this point. Are you limited to a stock block? A lot depends on that. But in general, if money is not a major stumbling point, I would say you want an aluminum block motor. Either a Bowtie or aftermarket gen I Al block or the C5 race block.

If you need to use an iron block, clearly a gen I Bowtie or aftermarket piece is the way to go for all out racing. What about transmission? Assuming a close ratio aftermarket tranny, I'd suggest you consider a centrifugal if cost is a factor. The lack of low and midrange torque won't be an issue, assuming you remember to shift! And a centrifugal will be cheaper and easier.

So, I could ramble on, and I can't give you turbo specific advice. But it would help to know about the rules you need to adhere to and what the budget is before people get way off-base on this.

Rich Krause

 

AIX does not restrict me to a stock block or even an iron block. However, what would an aftermarket aluminum block cost? I'm willing to take my time building this combo to make budget less of a factor, but I think that just for the engine I'd like to spend $6000 or less and build it mostly myself. For the turbo/supercharger and intercooler, piping, etc. I'd like to spend less than $5000. Fuel system about $1000.

Is this a realistic budget for 600 RWHP? If I was to break it down into the following categories, what would be realistic?

Engine (block, heads, internals, etc.)
Fuel System
Ignition System
Turbo / Supercharger
Tranny / Rear End

If it will take much more than $12K I'll be looking for sponsors over the winter and through next year.

Perhaps I could build a combo that would start out at 500 RWHP for $8K or so, and progressively add to it over the next year ('05) to make 600 RWHP if needed for competitiveness? I'd put almost all of my money into the engine itself and spend less on the turbo/intercooler/fuel system knowing I'd upgrade them later when needed.

I can run a Jericho transmission if needed, but it seems to me I might be able to make the T56 live since it's my understanding a very similar version of this transmission is used in the Viper. Don't forget, drag strip style launches are not a part of this car's operating conditions. As a matter of fact, I doubt I'll ever see 1st gear except for getting the car through pit lane. I'll need a very strong clutch but I don't powershift when I upshift on a road course. Overall the transmission sees a very easy life unless I miss a downshift or the like.

If I consider a centrifugal supercharger instead of a turbo what kind of cost differential do you think I'm looking at for this kind of HP range? Is it more than $2K?

 

it would probably be much cheaper to do with a blower.

IMO, I would use a t-trim, and pulley it for max impeller rpm at the max rpm you see while racing. With a decent motor beneath it, it will make the power you want and have a smooth linier powerband. turbos can be hard to make hook up

 

As Jordan said and I suggested earlier, a centrifugal may be the way to go. I think a T-trim maybe a little smaller than you want though, but is certainly adequate for 600hp. Race aluminum blocks are out of your budget range. Do you have a motor now? You are probably best off starting with what you have.

Rich Krause

 

The only motor I currently have is my stock long block that is in the car. It has just under 100,000 miles on it and has served me very well so far while I sort out the suspension on the car. Over the winter I'll put a fairly mild cam in the car to get me near the HP limit of AI for my weight and then start building another engine.

OK, if I go centrifugal supercharger, it seems to me that ATI has the best setup, complete with air to air intercoolers. It also appears their setup from Tbyrne with twin intercoolers is about $1000 cheaper than a Vortech with an air to water.

Are there any problems with a 396 with approx. 15 psi boost? Looking through some listings I've found a 383 and a 396 both cost about the same.

Which heads are best to use for an engine like this? I'm familiar with the AFR heads just from past experience with friends' engines but that's about the extent of my experience with SBC heads.

I believe the CR I would go for is 8.5:1 so what chamber size and dish size on the pistons would you recommend?

 

Go with the ATI and 396, but 9.1 C/R and racing gas is better in my opinion than 8.5C/R on pump gas for a road course application. 8.5C/R could be a little bit slow in response.

 

I think the twin ATI intercoolers are a neat setup. But they are small and will restrict airflow, to some extent. You might consider a larger intercooler.

Rich Krause