2871R goes rather nicely...

[S2central.net]

Its a 71mm compressor.

I'm not claiming '460' here by the way... All of the maths for estimating flywheel power is always a hotly contested subject - especially on this forum... It did 367 on GTech RR (nett at the wheels) on a UrS4 Avant that weighs ~1900kg (loaded with electric leather seats, aircon, has two fuel tanks a driver and co-pilot - both with a slight podge on to be fair).

It launches to 60mph in a sniff over 4 seconds. Its damn fast...

[urquattro-island]

does

Its a 71mm compressor.

I'm not claiming '460' here by the way... All of the maths for estimating flywheel power is always a hotly contested subject - especially on this forum... It did 367 on GTech RR (nett at the wheels) on a UrS4 Avant that weighs ~1900kg (loaded with electric leather seats, aircon, has two fuel tanks a driver and co-pilot - both with a slight podge on to be fair).

It launches to 60mph in a sniff over 4 seconds. Its damn fast...

he have an extra fuel tank???

[Billman]

i mean compressor inducer! I know you dint said 460. It was not for you. :-)

[Sonic]

When fitting a 2871r does it have the same problems as the 3071?

Does the hot side get in the way, meaning the engine had to be raised?
Does the downpipe need extending to reach the turbo?

Cheers

[denniselbows]

what about the maf position on this car is it still in the original location i thought with the gt bb turbos you had to move the maf to the boost side.?

[S2central.net]

MAF is in stock position on this one.

[Prophet_dlx]

When fitting a 2871r does it have the same problems as the 3071?

Does the hot side get in the way, meaning the engine had to be raised?
Does the downpipe need extending to reach the turbo?

Cheers

Any BTDT on the 2871 with k26 hotside in the S2 coupe. I'm really interested to use this turbo with Wagner evo or stock RS2 EM on stock engine mounts if I don't have to cut into the bodywork to make it fit.

very cool results by the way, perfect power to torque for my needs. could you post a complete plot from 1000-7000 rpm please, would be nice to see spool up and torque peak.

keep up the good work mate

[merlin's S4]

he have an extra fuel tank???

Des is also running LPG

[repo]

I think 2871 is with 54mm impeller. And yes, it can flow 460hp. As a matter of fact, that compressor can do +500hp, but the turbine cannot. Even 460 is too much for that turbine.

Exactly why 2871 is not a good turbo, perfect example of imbalance between turbine and compressor. Can spool up at 2600, but surges up to 4500-5000, if pushed even a tiny bit too far at that range.

Kalsket did 460 on crank with such a turbo years ago, and had tons of issues with surge. Car never got proper torque, even with phenomenal spoolup, as the turbo couldn't stand enough boost at midrange.

Also, egt's were constantly too high. Eventually causing the exhaust manifold to balloon, and destroy itself. EGT's get high 'cause of too narrow exhaust path.

[A80Avant]

i just had a look in garretts webside.I cannot find any 2871 with 54mm comp impeler.The biggest one has 53.1mm comp. inducer from all the models there,which is the same as the 3071 comp.inducer

[Prophet_dlx]

I think 2871 is with 54mm impeller. And yes, it can flow 460hp. As a matter of fact, that compressor can do +500hp, but the turbine cannot. Even 460 is too much for that turbine.

Exactly why 2871 is not a good turbo, perfect example of imbalance between turbine and compressor. Can spool up at 2600, but surges up to 4500-5000, if pushed even a tiny bit too far at that range.

Kalsket did 460 on crank with such a turbo years ago, and had tons of issues with surge. Car never got proper torque, even with phenomenal spoolup, as the turbo couldn't stand enough boost at midrange.

Also, egt's were constantly too high. Eventually causing the exhaust manifold to balloon, and destroy itself. EGT's get high 'cause of too narrow exhaust path.

Is there no relation between Mr Kalsket's gt2871 surging and his turbo's internal WG, the k26 housing and external WG coping better with this problem in this setup!?

for poeple that want around 420 hp it is a gain of 1000-800 rpm on spool up on an 3071 and you don't have to change the rods as you have to with highboost on an rs2 turbo.




cheers

[karlblues2]

RS2 injectors (360ccpm) are too small.

You could go with Bosch racing greens (440ccpm), but Des opted for Siemens 550ccpm to give loads of headroom - thats what I have mapped with.

I'm sure the Bosch 440s would work on this turbo (pretty sure its what 034 use) but I'd need to do them one or two in real-time before having any sort of confidence in chips to post to Australia. Now a real-time mapping session in the land down under would be really nice - hehehhh - who wants to pay for that - awwww please...

@Karl - with a set of Siemens 550 injectors, and this chipset of mine you'd be ready to play when the 2871R is fitted. I also advise you keep the cams standard, but I hope you have a mighty big intercooler - and maybe water injection to help with the higher air temps down there in the summertime.

Hi Paul
Thanks matey. I do have a large efficient I/C fitted and standard cams. I have toyed with water injection and / or a water spray bar too. I can easily source bigger injectors. Happy to discuss flight contribution and free accomodation Paul. I'm sure I could coral a few Audi enthusiasts with S2's to come and play too!

Let me know when you are ready to do it and we can talk more
Cheers
Karl
Oz
P.S. It was really hot here yesterday (39 degrees C) . See attached

[Nuvo]

P.S. It was really hot here yesterday (39 degrees C) . See attached

Thats hilarious.

[repo]

Wastegate has very little to do with compressor tendency to surge.

Of course high backpressure is one of the causes, and higher wg capacity helps that a bit, but reducing Backpressure significantly with wastegate most likely causes the boost to drop as well.

[repo]

And I need to say sorry, I am not hijacking the thread. Just wanted to point out, that check the EGT before launching with a software big time, as there might be a long term reliability issue waiting around the corner.

Another point was, that surge-wise these turbos are extremely delicate when it comes to controlling the boost, so wgfv duty in Your car may cause another to surge to death.

Back to the topic. Apologizes once again.