Turbo still not finalised ?

[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]

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.

[Billman]

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

[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.

[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.

[Thuppu]

Holset is used in heavy industrial machines/engines so propably they are quite reliable and they can be overhauled with small money. How early spool do you want on a 500hp engine? http://koti.mbnet.fi/pro-ht/Audi_URS...super_dyno.pdf

[prj]

Huge waste of money with the 2871R if you are on a stock car.
I would just go K26/K27 or a K24-7400, because it will be a lot cheaper..

If going for a T3 manifold, doing rods etc, then I'd go no smaller than a 3076R/0.82 or HX35 Super with larger hotside.

There is a question about "bang for the buck", and a 2871R delivers little compared to say a K26/K27, which bolts right on.
Also, with the bigger turbos you just drop down a gear compared to stock.

With a 2871R, it won't quite spool early enough, so you will be forced to drop down a gear compared to stock turbo anyway. Might as well go bigger and get a 3071, there will be very little difference to how you drive.

[JP]

Personally I'd never buy an 034 turbo again after my one had to be rebuild after less than 600miles. Paid extra for a warranty report never got the money back for rebuild or report. All because the turbos come with internal wastegate heatshield cores rather than external and they rub against the blades.

[diesel des]

Well a 2871r will do a real genuine 400 HP on a stock internal engine easy. If you have the right other obvious bits eg manifold, exhaust, injectors and intercooler etc. The smaller unit, s gt 2860rs would be over worked by q fair bit, so the 2871 is your best choice.
A kkk from a focus rs would get you close too. But its smaller. Think of rs2 power with a bit less lag.

The outright best turbo is a new efr kkk turbo. But its big cash and needs special manifolds. Pm me for contact details... Des

[macspring]

Des,

Thanks for your interest. Will pm you soon to arrange a date for a ride in yours. Very much appreciate the offer. I know macanmar would be interested too as he is just behind me in the preparation of his engine. I'm the guinea pig.

Would like an easy 400 bhp at the crank everyday of the week for a few years without having to worry about it or look at it again, with very early spool and good torque, ultimate power is not a priority as it is rare enough to go over 5k in everyday driving.

Don't quite yet fully understand the significance of the various choice of trims.

Will never be tracked.

Thanks.

[diesel des]

Right, deside what HP you want or "need". Be realistic. Buy the smallest turbo that will do that power. Or if you want to spend time on the track pick a turbo 50hp larger. More HP ALWAYS pushes boost startup upwards. This is where $$$ can help. A ball bearing turbo speeds up response a little.

Get a run in a car close to the HP you are looking at. The map 034 show for the 2871 is for the 48 trim, but they shiped me a 56 trim. This compressor is exactly the same as a 3071r, do just a comp housing change let's you use its comp map. That's what I run. Remember, I'm 15 miles on then north side of the border if you need a demo....

[macspring]

After re reading this thread and my two others about turbo choices, I've learnt a bit more.

I know I keep changing my mind, but only want to buy the turbo once. Will now be fitting a 3"inch downpipe rather than an RS2 one.

The kkk 26/27 seems like it might be too laggy for me, and so now thinking of this one ?

http://www.034motorsport.com/turbochargers-and-accessories-kkk-hybrids-k26gt2871-turbocharger-p-321.html

What do people think, has anyone got it fitted ?

Thanks for the feedback to date, and any further comments.

Regards.

[Ross]

As per PM my K26/7 has the lag but doesn't quite deliver on the power. Forget 420hp, more like 380 and perhaps 400 if pushed. Max boost ~3900rpm.

Prj, I think the problem here is that finding two identical K26/7 is difficult. I think it's been proven that the figures you quote are spot on for a newer one though.

That's why I am changing it - the little extra up top is not worth the trade in lag for me. Now for 420hp - I could continue to live with 4,000rpm.

[Rusty]

Our tests and limits vary depending on age,

Limit for my 91 CQ20v is 3.5%, car tested at .65% without a cat.

Limit for my 94 Avant is .5%, car tested at 0.01% with a cat.

They also tested the high idle (~3000rpms) on the avant, limit was .3%, tested at 0.03%.

Both myself and David use bolt in cat replacement pipes, 20 minute job to fit them for testing, also keeps them nice and fresh in the shed for when there needed :mischeif:

Yes, fast idle test is the one.

[prj]

K26/K27 with #8 housing is usually ~4000 rpm full boost in 3rd and when mapped properly 420-ish hp.