Chevy Optra Turbo
 

Hey guys, I know this car doesnt have any aftermarket support really, but i've invested plenty of time and money into this car and have finally turbocharged it. Currently Running a Garret T3 with a .57 inlet AR and 0.82 Exhaust AR. The car is only a 2.0L and im only managing 7psi at 5000 rpm. My Redline is 6500. We cant get anything higher then 8 psi out of the turbo due to the turbo being too big and not even spooling. Anyone out there suggest a perfect sized turbo to get mostly fully spooled around 2500rpm that has a T3 Flange to bolt to the manifold ?

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You're going to have to change your turbo and the manifold and its flanges. I'd recommend a simple T28 turbo from an old Nissan or if you even want some pep, a GT28RS for quick spool you're looking for at 2500rpm but otherwise, I have no other advice for you. Sorry!

And not to be mean or anything, you should've done your research first and did it right the first time around.

Your best bet would be to find a T25/28 to T3 adapter and invert it so that you're able to run something such as a GT25R or GT28/RS. Most T3 flanged turbos are going to be too big for you to run efficiently.

I did do my research, the ONLY mani for the car has a T3 Flange, Unless i spent a ridiculous amount of money on a custom manifold. As for the sizing, i looked around and when i bought the turbo (got it cheap from a friend) they sent the wrong size and its just going to cost too much to send it back and get a new one, thats why i was asking

Why don't you swap the turbine housing and wheel for something smaller?

just swap a .63 hotside onto that t3, your .82 a/r is way too big.

So far the shop that i got the work done has suggested a t3 50trim with .48 AR

that's a pretty small turbo.

that would help for sure. but it wouldn't' spool quite at 2500 rpm.

getting a smaller hotpipe would help spooling as well as not having a humongo sized intercooler.

have you thought about cams as well?

Piping and intercooler size aren't going to have great effects on spool time. I suggest you don't give advice until you pickup some more basic knowledge yourself judging from the threads you've started lately.

I'll check my shop and see what I have there. I have an extra turbo kicking around but I don't know what flange is on it. Is yours internally wastegated or external because the snail I have is internally gated for sure.

Berz out.

Actually piping and IC size does have a huge effect on spool time. The longer it takes to get air to your motor by filling up all the pipe and IC area the higher your rev's are going to be. Choosing the right size piping is as important as picking the right turbo. There is a reason people don't run 4" intake piping on small turbo's. What size are you running now for piping? Anything more than 2" is overkill on most applications. Not saying yours is oversized just saying it does matter!

Berz out.

compared to the turbo sizing issue the size of the intercooler and piping are going to be negligible. As an example I was running a t3/t4 57trim on my lsvtec at about 10:1cr then I built it and its about 9:1 now I also went to an intercooler that is over twice as large and from 21/4" to 3" chargepiping and then i went to an h1c with an 18cm^2 hotside (~1.00 a/r) and full spool only went from 4500 to 5500 rpm. This was with no head work and only going from b17 to gsr cams.

You're completely right :D

The setup i have is using an external wastegate. As for the piping size its 2.5" piping and the intercooler is 27"X5.5"X2.5" so its not a huge IC. I just wanna be like triple sure that the next turbo that goes on will do the job right.

post pics or it doesnt exist! :haha:

i cant believe someone turbo'd a optra props to you :thumbsup::thumbsup:

Ugh I forgot to ask.. what is your exhaust setup? If its being choked by a restrictive cat then it doesn't matter what size turbo your running it wont spool. I would "hope" your running a full 3" (2.5 absolute minimum on a 2.0L motor). Also with a 2.0 2500 full spool is rather low and any turbo that has full spool that low probably wont be able to keep up once you hit the higher RPM range (depending on how much boost you want to run). I know it sounds good and all to have full boost at low rpm but in real life it sucks. I ran a 1.6L with a T3 and it was great but when I put that same turbo on my 1.8 liter I was in boost just cruising down the highway.... 3k just whistling away in cruising mode sucks balls.

How are you tuning it?

Edit just reread and saw your redline is 6500 (I'm spoiled with 9K honda's) so 2500 is probably where you want to start seeing boost.


Berz out.

In the OP's car 1000 rpm is a pretty big deal only revving to 6500. Anything he can do to induce faster spool without losing top end is going to be advantageous.

Berz out.

Yes it would but the biggest difference in what I mentioned was the hotside that is 30% larger, the other changes were negligible.