I have narrowed my plan for my turbocharger down to two turbos. I can't decide which one I want to use. my plans for the car are to build a car that will compete with 4 digit supra's and vipers with full interior and still fun to drive. this car will be a street car. not daily driven but could be if I wanted to. my current mods to support these numbers are lightened and balanced rotors along with the rotarting assembly and a set of goopy seals.
the motor is a pretty agressive street port and and the motor is dowel pinned too the fuel will be e85.

secondaries

exhaust

dowell pins


The garret gtx4508r is ball bearing turbo with a 79.8 mm billet compressor and a 108mm turbine. The other turbo im considering using is the gtx4202r which is also a ball bearing with a billet 75.8mm compressor and 102mm turbine. I wonder what whp each turbo is likely to make if at 30psi or less. I'm concerned that the gtx4202r will not make enough power to keep up with the 4 digit supra's and vipers on the highway, however I'm also concerned that the gtx4508r will be a little more sluggish and then when it comes online it will make so much power that I cant get traction even with the 335 drag radials and the t56. any thoughts? I'm thinking I would like the car to be in the 800-1000whp range.

 

please note considerations should be for the 20b not the 13b

 

Subscribed. I'm also looking to make 800+ reliable rwhp on a 20b and am leaning towards the 45r but I'm not sure about the response.

thewird

 

HP goal?

It is best to run the smallest turbo that will achieve your ultimate HP goal within its efficiency range. IMO most people run turbos that are 1-2 sizes too large, and lose breadth in their power curve as a consequence.

I had very good results with a GT4202R, making ~620whp@17psi on a conservative tune, and over 500whp from 3500-8500RPM. I have not looked at any garret maps lately but I think it maxes out around 700whp@2x psi


EDIT:
what about gtx4202R? That should get you up around the 800whp. the x4508r is a bigger frame but not much more compressor flow. Maybe 900 or so potential whp.

On a side note, how much money are you planning to sink into the chassis to hold this kind of power? My understanding is that 600-700whp is the upper limit on a FD without major modifications. I know the FC started to go downhill after 500whp...

 

IronMdnX (sp?) was running 800+ on E85 before his unfortunate run-in with his buddies truck. I don't remember what turbo he was running...

ErnieT was running (IIRC) a 42R at ~830whp on E98 before selling his FD.

 

If you haven't physically seen a 45R I suggest you do. It is bigger than the 42R the same way a 42R is to a 40R practically. It is a huge turbo. We have done numerous 20B builds all running the older cast GT4202R and they will easily make 500+whp around 10psi on mild portwork. If response is a concern run the GTX42R, the GTX42R will flow pretty close to the GT4508R. Another option would be like the turbo I have sitting here. It is a 4508R in a 4202R package. It runs the 42R compressor cover and lightened aluminum backplate with a TiAL housing. Shaved off 24lbs and fits in the same envelope a 42R would. Personally 800whp in a FD is useless even at speed on the highway.

~S~

 

why is 800whp unuseable in an fd when 1200whp is in a supra or viper? my maximum goals for power will be 1000whp as far as what i will end up using... That depends on what I can physically control wether that be 500 or 1000. time will tell.

 

my 4508r is in a 42r housing. titan put it in there i guess. i am going to try the 4508r and ernie t's old turbo and see the difference in the gtx and the gt.

 

Its too bad nobody has a GTX4508R dyno plot for a 20b. Or maybe a regular GT would be enough to compare actually.

thewird

 

A 4202 will not get you 1000whp. a 4508 will be borderline even at high boost.
That said, my suggestion would be to use the gtx4202R. If you max out the turbo and think you need more peak horsepower, and you think the chassis can take it, then you can always upgrade. I suspect that you never will.

 

i **** my pants at 600whp

 

in that case, I do not want a ride in your car anymore.

 

From the 1002hp FB thread...

 

Would you mind posting / PM'ing a photo or two of that?
I'm highly interested in that!

 

I would really like to see it as well. being that its in a 42r housing what are the measurements on your inducer and exducer for the compressor and turbine side?

 

@800whp a fd will pretty much decimate all ,and gets really really scary , but i think 1000hp should be doable ,of course not being an idiot when you drive around town
only sad thing about all that power is the laundry list of parts that are going to keep breaking
go for it though !!!!

 

As long as the motor holds I don't see much else breaking at that power level with the right drivetrain setup. Vettes vipers camaro's mustangs and supras seem to do it quite a lot. Although the parts haven't been cheap I think it will hold. But time will tell I suppose.

 

Well I wouldn't say "really really scary" but if its something new then, sure, it'll be scary (only for a little bit). I think its a lot like a roller coaster, given a few rides on it, you'll know what to expect and it'll be "less cool".

However, unlike that roller coaster, it takes only milliseconds to screw it up (specifically playing on the streets). In the old car, the steering was worthless. nail it WOT @ 25-something psi and it was like trying to steer a laundry basket on ice - really.

I just don't agree with that 1,000hp engine setup in a car without a cage. Just my 2 cents.