Any Good Low Boost Single Turbo?

[bradsm87]

I'm looking for a turbo for a high compression, high flowing 3L motor (Subaru EZ30 horizontal 6) that will make 300awkw on as low boost as possible.

All the new single turbos suitable for that power range on low boost aren't very exciting in terms of compressor efficiency island width because they are all designed for high boost (eg. Garrett GTX, GT and BW EFR)

For example at 0.75 bar, the GT3582R is at least 68% efficient from 22lb/min to 48.5lb/min, a range of 26.5lb/min. The GTX3582R is from 22 to 54, a range of 32lb/min

BUT twin GT2860R 707160-5 is at least 68% efficient from 23lb/min to 62lb/min, a range of 39 lb/min! So it's efficiency starts at the same spot as the GT3582R but ends 14lb/min further!

I want this kind of thing out of a single turbo and I can't see ANY. Is there anything out there?

Edited January 12, 2011 by bradsm87

[paulr33]

whats wrong with small frame GT30 ? GT3076

why so big if you dont need that power ange

[bradsm87]

I wish I damn could but generally a turbo that can flow efficiently for 300kw at say 1.5 bar will struggle to efficiently flow 250rwkw at 0.75 bar, no matter how big the engine. Look at how the compressor maps move up and to the right instead of straight up.

Eg. a GT3076R will make 300rwkw no worries on an SR20 at 1.6 bar but it generally won't make 300rwkw on a 3l motor at 0.8 bar, u need a bigger turbo or more boost.

[bradsm87]

Also I can't push the turbo to it's very limits because charge air will get too hot because it's going on an unopened engine with 10.7:1 comp cast pistons so I wouldn't want it going past the 70% efficiency mark. It'll need E85 and low cool boost to stay alive!

Edited January 12, 2011 by bradsm87

[crack]

these have had my interest for a while

[bradsm87]

these have had my interest for a while

Very interesting stuff.

I'm more just looking for a conventional turbo, just with the right compressor wheel to suit what I want for $2300 max.

[wasnt me]

I think you will struggle to find anything that will make the power you want at such low boost.

it could be done but would need to be up around the GT40 range. but the lag would out way the benefit of making 300awkw imo.

What about a GTX3582 twin scroll rear and 1.06 it should keep the heat out of it and will close to your power goal on E85..

[R31Nismoid]

problem is a GTX35 will be laggy as well. it might make the power but it isn't going to feel crisp at all. it will drive very lazy.

that's the problem with small displacement though really.

i doubt there is any normal turbo that can achieve such an aim on a 2.5L

[wasnt me]

problem is a GTX35 will be laggy as well. it might make the power but it isn't going to feel crisp at all. it will drive very lazy.

that's the problem with small displacement though really.

i doubt there is any normal turbo that can achieve such an aim on a 2.5L

In the OP he stated the engine is a EZ30 (3L),

but yeah it wont be an ideal set up but will give the numbers he wants and thats about it...

[wolverine]

It seems like the closest thing to doing the job is a GT3582 but thinking a little sideways would one of those GT3576 (ford XR6 hybrid things) go close to doing the job?

[R31Nismoid]

Well they are on a 4ltr lol, that's s fair increase[ over a 3.

In the OP he stated the engine is a EZ30 (3L),

but yeah it wont be an ideal set up but will give the numbers he wants and thats about it...

ah yr, missed that.

either way even with a 3ltr its not going to come easy.

the only way would perhaps be some hybrid turbo, and we all know the lucky dip that goes there.

[paulr33]

how sure of this are you? al has a 3076 on his 3 litre and it makes tons of power everywhere and it makes over 300rwkw

why on earth would you go for a Gt35xx when a GT30xx will do what you want, earlier, more power everywhere and should have enough peak

are you saying the 3076 is too small? ref; "wont make 300rwkw at 0.8 bar, need bigger turbo or bigger boost"

if you size the housing correcly then this shouldnt be a problem

ie dont fit a mega small housing and choke, fit a larger size housing

[R31Nismoid]

issue is low boost as possible, thing is even with a 3Lwith a 3076 you are still looking at what, 18psi or so?

depends on ones definition of low, but in mine... that's now low, but there is no stantout alternative.

[bradsm87]

How does a GT3582R compare to twin -5's on an RB26 or RB26/30 in terms of boost threshold and response?

[wasnt me]

yeah agreed... when OP said low boost he meant really low .75Bar

If it was my car i would put the GTX35 on in. then see how much boost it can hanle

might even make 400awkw

[bradsm87]

how sure of this are you? al has a 3076 on his 3 litre and it makes tons of power everywhere and it makes over 300rwkw

why on earth would you go for a Gt35xx when a GT30xx will do what you want, earlier, more power everywhere and should have enough peak

are you saying the 3076 is too small? ref; "wont make 300rwkw at 0.8 bar, need bigger turbo or bigger boost"

if you size the housing correcly then this shouldnt be a problem

ie dont fit a mega small housing and choke, fit a larger size housing

That only solves the problem on the exhaust side. The 76 compressor won't flow 300rwkw at 1 bar. U need to size up turbos to make same power on lower boost, regardless of engine size. eg. The Perrin EZ30 used a GT3582R to start with and made 300-320awkw with a GT3582R at 15 psi.

Looks like the extra cash for twin -5's might be worth it. It would allow shorter exhaust runners being a boxer engine, just a lot more stuffing round with oil/water lines and pipe work.

Edited January 12, 2011 by bradsm87

[bradsm87]

yeah agreed... when OP said low boost he meant really low .75Bar

If it was my car i would put the GTX35 on in. then see how much boost it can hanle

might even make 400awkw

LOL at seeing how much boost cast 10.7:1 pistons and pinkey finger sized rods can take.

[wasnt me]

LOL at seeing how much boost cast 10.7:1 pistons and pinkey finger sized rods can take.

seriously though, your engine wont last forever making that sort of power and will need a rebuild before too long...

keep that in mind when choosing your turbo.

[Lithium]

I know you didn't ask this, but IMHO you shouldn't be worrying about flowing over 50lb/min on .8bar - even on an EZ30, unless you have got pretty fancy with it. Also if you are going to be using a lowish boost level and E85, a few points of compressor efficiency aren't going to break the thing - I'd be worrying more about minimal exhaust manifold pressure.

Look at the compressor map for the Borg Warner S300SX 83-75, I would be leaning towards one of those with the 1.00a/r twin scroll T4 turbine housing if I were doing what you are looking at doing.

People have done cool things with low boost on EZ30s but they are pretty fragile. A mate of mine actually has a forged/turbocharged EG33 in a GC8 which so far makes pretty decent power on low boost though its pretty hard to keep cool haha.

[R31Nismoid]

-9 would be the better choice for 300 wouldn't they?

roughly around the 15psi mark is all you should need given a 2.6 needs around 18

this is all subjective as head and flow have a fair factor here too.