Turbo still not finalised ?

[A80Avant]

When posting graphs of turbos and power figures, it would also be helpfull to tell people what the engine is like as well. A fully refurbished engine will make a hell of a lot less, with the same turbo than one with head porting, cams, lightened materials larger valves, EM/IM differences etc.

That HX35 Super looks brilliant from that graph, but it wont produce 500+hp on all engines.

Very obvious example, JPs previous GT30 runs, when he made 525hp on a GT3076R 0.63AR and 479hp on a GT3076R, 0.82AR.

Does that mean that everyone should choose the 0.63AR option?????

If we dont mention the full head porting and same cams use on the 2 setups and the 0.3bar difference, then wrong impressions are made.

[A80Avant]

David,
i have had and used the 3071R 0.63AR and i can send you logs that i have done with spooling on VEMS.

I loved the turbo on VEMS, and disliked it on motronic, but i am convinced that a better tune on the motronic will provide the same results i got with VEMS.

It's great if all you are looking for is 420ish hp, and although the power graphs fall after 5500rpm in terms of torque, you dont miss any of it on your seat 'bUt' dyno.

The only issue you may have with tuning, is that as you dial more boost for the early gears, the higher ones will spool even earlier and eventually you will get some surging for a few rpms when you get WOT on 5th and 6th from 2000rpm.
It is not detrimental for the engine/car and my 3071R when taken off, was as good as new, no play and ready to be reused.

However, that can easily be mended with a boost controller, which can dial different boost for different gears, and you have the problem solved. You ask for less boost on higher gears and lower rpm, so the turbo does not surge, and believe me, even in 1.5bar this turbo is fast.

Another easy way to get rid of surge is the 0.82AR, but at cost of some early spool, on all gears. I dont have any experience with that though

As for the precision turbo, again no experience, however i read an article online that their core bearings are not THAT good in a sense quality. They were saying the ceramic coated ones, are more suceptible to damage than the normal ones in oil starvation etc.

[Billman]

You should first decide what you want from the turbo and then we can give opinions.

[prj]

0.82 A/R 3071R gives ~3800 full boost in 3rd and much stronger top end, compared to 0.63 A/R, which gives ~3600 full boost in 3rd.

Talking about standard engine...
I don't think the 200 rpm are significant enough, because you will be using exactly the same gears anyway, but that's just me

I've tuned both options a few times, and without head porting there is slight surge with 0.63 housing, but not very hard to map out without really hurting spool in lower gears.

[A80Avant]

from a quick log i had 2bar at 3440rpm on the 3071R 0.63ar on vems, and that was on ADU cams and cam pulley. Stock head, and uprated pistons and rods. No other mods enginewise. The head had only been serviced with original parts. Compression close to 9:1

[prj]

You forgot gear.

[A80Avant]

Sorry.
3d gear

sent using Android

[macspring]

Apologies regarding the lack of detail regarding the spec. and the use to which the car will be put.

1. Block just build by JP using uprated rods and new pistons. 3B lighten flywheel, all balanced. South Bend clutch.

2. Head fully reconditioned, and stage 1 ported by JP, S2 ABY cams.

3. RS2 airbox

4. Wagner RS2 EVO intercooler.

5. MTM front inlet manifold.

6. Wagner RS2 exhaust manifold.

7. 3"inch downpipe, with extra bung for wide band probe for additional feedback for mapping.

8. 3"inch Miltek system.

9. Cat bypass pipes.

10. Custom chip on motronic by S2 Central.

11. Std ABY S2 gearbox. No side stepping the clutch at any revs. Will never be tracked.

12. Target - around about 400bhp all day long, everyday, don't want at look at it again for ages, except regular maintenance.

13. Essential early spool for 90% city driving and occasional motorway.

14. Suspension, brakes, wheels, seats, lights, wipers are already dealt with and fitted.

15. Edited - Forgot to include the fact that it already has a Bosch Motorsport 044 pump fitted courtesy of Macanmar.

Various turbo options spinning around in my mind, in no particular order;

1. RS2 hybrid turbo.

2. kkk26 (#6)/27 - seems a bit too laggy for me?

3. 034 K26 / 2871 - unreliable - see JP's post above.

4. GT2871.

5. DJ Jones's turbo - CT357 ? He seems very pleased with it ?

6. GTX3071 ? Newer and better than a GT3071 ?

7. Small Holset, i.e. smaller than a HX35 Super ? Is there such a thing ?

8. ???



If possible can people mention the pros and cons of their suggestions to put their comments into context.

And also where to source the various turbos mentioned.

While cost is naturally a factor, it is more important to get the right one, even if it is dearer as I'll feel where the extra expense went every time it spools.

The reason for dithering so much is that I only want to buy one turbo once and get it mapped once.

Thanks for everyone's post's / interest in this thread. Hopefully it is also of use to others watching this thread as well.

[Billman]

If you want no more than 400 hp then go for the 3071.

The Holset are cheap turbos capable for 500+ hp and very durable but of course they would spool later than a tiny Garrett.

[Jamo]

misconception about spool and drive ability and also 034 do not make the k26 / 2871 or 3071 you can get it from any garrett dealer with garrett kkk hotside

034 had their own range of hybrids which JP was referring too

Have you driven or been in a car that has 400 bhp there a major difference between turbo response and full spooled boost and you need to out and experience these cars rather than from the online quotes of power and response as they are not the same

[JP]

In an ideal world you need to go out in Ross's car and see what it is running like with his turbo as you have pretty much a near identical bottom end and cylinderhead setup (p.s. its a stg2 head ).

He is also running the Wagner evo mani. Not sure about the rest of the setup re exhaust intercooler etc....

The only thing different I'm aware of is he has a port matched intake

As a reference he says of boost the car keeps up with 2ltr tdi's is very responsive and is in the 400+ bracket you are seeking.

[A80Avant]

Yes, Ross car also doesnt have a reverse inlet manifold and that would also be a + in your setup.

I agree that the ideal thing to do is to get a ride in someone's car with 400hp. Shame i have lost my time travel ability otherwise i would have taken you in mine(mine when on the 3071 also had the original RS2 inlet manifold.)

I have realised that camshafts will also play a major role on the way the car behaves and produces power. Not knowing the excact outcomes, i would suspect that the 3071 0.63ar should produce early boost figures (as early as 3500rpm for high boost and obviously start faster on low boost by perhaps 3000rpm), but you would possibly also 'feel' the drop after 5500-6000rpm as well. (Hence prj suggesting the larger hotside to cure that and make some more hp.)

I think the only major difference with the K26/27 hybrid to the 3071 is the way the boost is delivered, with the latter being slightly faster. I would have more info on that once Ross takes me for a drive!!

I bought my 3076R from turbodynamics and although more expensive than 034,i wouldnt buy from 034 or ATP as when you add all the shipping and customs you end up with no big difference in costs + you have a big hassle when it comes to servicing-reconditioning.

If i were to get a turbo NOW on your setup to make 400hp, i would probably choose the holset HX35 with a billet wheel and a small hotside (whichever available). Reading about the specs, i believe it is capable of making more than 400, and not be far off the early boost targets i have for myself. Remeber, as your engine will have a high compression ratio, that helps boost build up and responce off boost, while making it more knock prone on turbos that like high boost anyway. HX35 is equal to GT3076 territory though, so you may consider it slightly on the higher hp side.

[prj]

HX35 Super with small hotside is not equal to GT30R territory.
It is a 450hp turbo, and could be perfect for this setup.

That 512hp graph you have seen posted here is with ported head, tubular manifold, meth injection etc etc... That car is an UrS4, which ran low 11 on HX40 Super with everything inside the car present... Might give you an idea on how much has been done to the engine on it. It is definitely not the norm to get 500+hp from that turbo.

[A80Avant]

So what do you think a gt30r with the small 0.63ar hotside and a non ported head will produce? I say no more than 460-470 on our engines due to egt and drop in boost pressure at the top end.

se nt using Android

[prj]

I think I would pick a 0.82 A/R 3071 over a 0.63 3076...
So I can not answer that question