What turbo?

[mpg99999]

I am currently researching what turbo to use. The engine is a Nissan SR20DET (It comes stock with a T25, or T28, depending on the car). It is a 4 cylinder 2.0 liter engine (about 122 CI). I assume 90% VE for all my calculations. The engine redlines at 7500 rpms.

I want a turbocharger that will support about 350 Wheel HP at around 18-20 psi. I want it to have very good spool characteristics and be able to run at higher boost pressure’s continuously in situations such as a road course.

I have been looking at the Garrett GT28RS. It is dual ball bearing. The turbine wheel diameter is 53.85mm, and it’s a 76 trim and the housing has a .86 A/R. The compressor wheel is 60mm, trim is 62, and the housing has a .60 A/R. At 10 PSI, between 4,000 and 7,5000 rpms, the compressor never drops below 72% efficiency. It seems to be a very good match, but I am no sure if it will flow enough to make 350 whp with the relatively small turbine is uses. It will however spool extremely fast. I have considered running a divorced waste gate or even welding shut the wg and running an external one to help with flow. I am open to any suggestions. Thanks in advance.

-Mike

 

[beaverjones]

Last time I looked garrett had a se-r with gt28 on it.Think it made 280whp.Everyone who drove it just went on and on about how much quicker than 280hp it seemed.Disco potato if I remember right was the car.

 

[mpg99999]

That actually isnt garretts car. You are correct though, it is called the Disco potato. The turbo was named after the car, both called teh Disco potato, so named because of the cars color. It is in the magazine Sport Compact car. The car is a B15 sentra (not an SE-R, but it has an sr20). It was using JWT C1 cams, but had a small exhaust. SCC is also using the DP turbo on there project S13, which made 274 whp with stock cams and a 3 inch exhaust @ 15 psi. Just so there is no confusion, the DP is the GT28RS. Garrett also makes a GT28R.

-Mike

 

[Retracnic]

The GT28RS will not generally support 350 horsepower for this application. At 7500 RPM @20 PSI, you will need to flow approximately 38-40 lbs/min of air. The GT28RS has a maximum flow rate of roughly 35 lbs/min, which puts you a tad off the compressor map.

Regards,
Bryan Carter

 

[mpg99999]

Yeah, at 7500 RPM @20 psi it is on the edge of the compressor map. But, that is still 60%, which isnt to terribly inefficient. Between 5000 and 7000 RPM it does not drop outside of the 72% island at 20 psi. I am pretty sure that this is the turbo I will run. I am gona port the housings and do a few other tricks. I'd really like to see 350, but I will be happy with anything over 300, and I know I can get that.

-Mike

 

[Retracnic]

Well you're free to try. The GT28RS is definitely well suited to this application, I just don't think it's up to the task of providing sufficient flow capacity for the power level you are trying to attain. Besides being well into the surge limit, the severe dropoff in compressor efficiency is going to cause your inlet temperature to skyrocket. A serious intercooler becomes a 'must have' item. Plus charge density takes a nosedive as compressor efficiency drops.

But I'm sure I'm not telling you anything you haven't heard before.

Good Luck
Bryan Carter

 

[toytech]

On my turbo project I am using a Garrett gt2540r it flows 44lbs per minute of air and sounds perfect for your application. Mine is going on a 4agze Mr2 motor which is a 1.6l. It is a t25 turbine housing with a bigger t28 wheel in it, and a 60-1 compressor housing dual ball bearing of course and it will bolt to a sr20det manifold with custom intercooler piping being neccessary. Should support to 450+ at the crank.

 

[mpg99999]

At 20 psi its not that bad. At 5000 RPM, it will be at 72% efficiency, at 6000 RPM it will be even more efficient. At redline it drops to 60%, which isnt great, but its not horrible. I will be running a Front mount Intercooler. It does look like its a little bit into surge at lower RPM. I wont run 20 psi too often, and with the dual ball bearing center section, I hope this wont have a negative effect on turbocharger life. It looks like if I drop to about 18 psi, I wont have any surge.

I remember one of the garrett turbo's, although im not sure which one, had a pretty bad compressor/turbine speed mismatch. I want to say its the GT25, but im not positive.

-Mike

 

[2ofdem]

Having some experience with these engines the hks GTRS is probably the best suited turbo for this sort of HP.

 

[GotBoost]

Completely new to this Board (first post). I would look into Precision turbo and a Full-Race Mani. No problem making 350 WHP and both great people to work with.

http://www.precisionturbo.net/sportcompact.php

http://full-race.com/pd_manifolds.html

 

[javierb14]

personally, i think the t25's are great turbos for daily driven street cars. my old nissan 1.6L had a gt25 on it and the response was great.....almost instant torque you may also look into using a larger turbine though, some of garretts turbine maps can be found here

http://www.atpturbo.com/root/turbine.htm

i thought about using a smaller GT series turbo on my se-r, but i decided to use a larger T3/T4 since the car is now more of a drag car.

javier

http://www.full-race.com