Best turbo for 550hp I5

[Billman]

I would go with a Holset HX40 Turbo. Very nice impeller design and nice price.

[repo]

I am yet to see a good torque plot on HX40 and I5. Seen a few +500hp curves, not a single +550Nm.

Super40 gives a ton of power though, still not too responsive.

[Bambi]

034 motorsport claim 500Hp and spool arounf 3000rpm for the KKK/GT3071 anjd ability to run over 40PSi. Can I believe these numbers....? From what I've read here, it seems I shouldn't.

I agree with the smaller turbo better response route for the track. Maybe 460Hp is not so bad to get sharper throttle responce. Where would be the best (cheapest) place to buy?

[A80Avant]

the way to achieve these figures that 034 claims is to really get all top parts for the rest of the engine,meaning big intercooler,reverse inlet manifold,tubular exhaust manifold and run it on 40psi.(2.7bar!!)
These garrett turbos claim to work on very high pressures and still be able to give out power.If you build an engine capable of holding that pressure without hoses coming out and gaskets blowing out,then you may achieve that 500hp.IMHO i would get a bigger turbo with a bit more lag and try not to go over 2.0bar.

besides if you also account the fact that these turbos tend to spin very fast and produce a hell of a surge in low revs,you end up either paying an extra 1500euro for cylinder head machining and cams,or your tuner will have to stall the turbo down low so as not to create the surge.You end up having full boost at 3600-3800 rather than 3200 which this turbo is capable of producing and thus why not get the GT30R(3076) and have full boost @ 4000-4200rpm?

[Faheemo]

My 3071 ran 460hp with a small AR - so i reckon a large AR on 3071 may get you close to 480hp.
With Race fuel and on the tuning limits i reckon you can squeeze 500hp out of a 3071.
But then again why stress when the 3076 should do it with ease.
I guess it's up to weather you can live with the lag of the bigger turbo on track.

[A80Avant]

that is right.The 3071 will make very good hp with race fuel! but it is on it's limits.

[Bambi]

what's the effect of surge? What do you rekon I could get safely on 95octane? I do have a 7A exhaust cam and flowed head with SPM rods. Did you have surge problems Faheem? I see your car spooled at 3600rpm. Would you really go for th 3076 all said and done?

[A80Avant]

mine spools aroun 3800rpm with stock rs2 cams and stock cyl.head.The fact is that this turbo could spool as low as 3300rpm or 3400rpm.The 7A cam will give more lag as well...
on 95oct RON i think you would barely get 370hp-380hp crank on that turbo

[GazzaG60]

my sc61 is giveing me spool at 3k on motorway it spools 500 sooner on motorway. i was suprised at this. full boost is 4500 id say to not be over the top. it pulls for longer than the enigne will rev. i run 1.4bar for what i believe is over 400hp.

[Faheemo]

what's the effect of surge? What do you rekon I could get safely on 95octane? I do have a 7A exhaust cam and flowed head with SPM rods. Did you have surge problems Faheem? I see your car spooled at 3600rpm. Would you really go for th 3076 all said and done?

Dont recall any surge problems, Preggie tuned the car, he would know better.

Cant really say which turbo i prefer, cause i melted a piston before the 3076 was tuned fully.
What i can say is that the 3071 .63AR comes in much more harder than the 3076 .86Ar.
3071 was like a on/off switch whilst the 76 was more progressive.

I did the Quarter mile in 12.3 secs with 3071 , so not short of hp aswell.
A safe bet would be a 3071 with a bigger A/R. and you would be able to do gymkhanas aswell.

Purely tracks like kayalami and maybe 3076 to chase down the turbo M3's.
BTW: Javad advised me not to use a small AR on the 3076 - says it defeats the purpose.

[Jamo]

BTW: Javad advised me not to use a small AR on the 3076 - says it defeats the purpose.

Aronmatic2 has put this one to bed his car flew on a 3076 and .63 with around 470 bhp

4wheeldrifter was planning the same combo although his plans have probably evolved

[Faheemo]

Aronmatic2 has put this one to bed his car flew on a 3076 and .63 with around 470 bhp

4wheeldrifter was planning the same combo although his plans have probably evolved

Ok , to re phrase ,javad advice was for my application, which is mainly drag racing - it would defeat the purpose.

May suit track track racing better ? dunno

Arons dyno was impressive -very early spoolup - but i would expect more than 470hp from 3076.

[trondsen]

Hi, I have had both gt 3071 and now gt 3076.. braked 445Hp/645Nm @ 2.0 bar in engine with 3071, and 506Hp/681 @ 2.1 bar in engine with 3076..

I can`t recognise my car with 3076, but I changed cams/boost regulator/ adjustable wheel for the cam too, at the point of turbochange..

Nice curves..

[Billman]

I am yet to see a good torque plot on HX40 and I5. Seen a few +500hp curves, not a single +550Nm.

Super40 gives a ton of power though, still not too responsive.

Hi Repo, maybe your right.
Can you maybe post some maps of Holset on the I5. Till now i only seen them on small Hondas and 2 Liter Mitsubishis so it is not very well. Maybe with the bigger displacement it would be better.

On I5 only this one:

http://www.s2forum.com/forum/showpost.php?p=53629&postcount=1

If i get the time till sommer i would put the HX40 with 56mm Compressor Inducer or the Super40 with a machined K26 turbine housing and see what would it do. problem now is that i dont have the place here to do such mods without having to pay many Euros on a garage. Still need to learn to tune properly on VEMS (will post some timing maps the next days in my Project thread for comments)

[repo]

Sorry, I haven't done any I5's with Holset, and dare not to post other people's plots.

Here's a clip of super40 on S2:

http://promo.pp.fi/temp/vedio/AC_drag_2007.wmv

Like said, makes tons of power. Still does not give best response when launcing.