GT2871R Turbo Qurestion...

[DaveT]

Hi Guys,

I've been reading URquattroGus's project thread, especially the last few pages taking about turbo maps, boost pressures etc. I want to ask for some thoughts as to the problem I have...

Audi 1B 10 valve engine with EFI and custom ECU, fitted a KKK/Garrett GT2871R Hybrid Turbo .63AR from 034 motorsport.

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

Boost picks up absolutly fine, starts to come on 2500RPM and full boost by 3000rpm but it just doesn't feel like there is much power. Get to 4200rpm and it just takes off. boost is holding at +.6 / .7 bar quite hapily all the way through, afr's are stable at 12, cam timing has been checked and double checked. I just don't know whats wrong, or was this not a wise turbo choice...?

Any advise greatly recieved...

Many thanks

Dave

[driftin jo]

Surely you mean .63 AR

[DaveT]

sorry typo, you are quite right i did mean .63AR!!

[prj]

0.6 bar boost? What do you expect with 0.6 bar?

Who mapped the car? What ECU are you using?

[adam g]

Even in standard guise they run about 1 bar boost. With efi you should be able to wind it up to 1.5 at least

[prj]

Yeah, I'd run more than 1.5 peak for sure, but need to know what you are doing.
You can't tune a car by saying "ok, I want 12 AFR, because someone said it would be good that way" and "I want xx amount of boost".
That's just not how tuning cars works. That's why I asked about ECU and mapping. To me it just sounds like you or your tuner isn't doing his job right.

[DaveT]

Thanks for your reply,

I want it to feel like standard, only when i'm happy I was going pull timing control accross and start increasing boost. The original had great power from 3000 rpm. I really wasn't expecting it to take off at 4200rpm. The 10 valve was known more for its torque as opposed to topend power.

I've tuned it so far, I'm using a megasquirt ECU running fuel only, ie original ECU running timing for the time being and EFI only takes over from the k jettronic mechanical injection.

I'm beginning to think it was a bad idea to install a supposedly better turbo at the same time. I'm wondering if the exhibited behaviour is expected (by those who know far more than I) of the new turbo...

Many thanks

Dave

[prj]

There is absolutely nothing wrong with the turbo.

The fact that you are using the original ECU for timing and not remapping it, is the problem.

Fuel, spark, boost, all is related.
Get timing onto megasquirt as well, and get it properly tuned, by someone who knows what they are doing.

Either that, or start reading _lots_ of books.
Designing and tuning high performance fuel injection systems by Greg Banish would be a great start.

If the car is making full boost at 3000 rpm, and it feels flat until 4200 rpm your fueling or timing is completely out.

[DaveT]

Thanks for your reply,

I understand that spark, fuel & boost are all related. That the main reason why i'm running standard boost with the standard timing map is to minimise variables.
So, if the turbo is a good one for the engine and wouldn't cause a 'power band' from 4200 rpm then i've got the fueling wrong...

I'm just purchased the book you recomend, so there is some bed time reading for me when it arrives...!

What would you think, more of less fuel 3000 to 4200 rpm?
Can you recomend anyone to tune properly?

Many thanks

Dave

[DJones]

Your GT turbo will spool so much quicker than your old turbo and the timing is probably miles out at a given rev vs boost.

As PRJ said you really need to include timing and get it mapped properly.... and you will reap the rewards for your efforts..

[prj]

Thanks for your reply,

I understand that spark, fuel & boost are all related. That the main reason why i'm running standard boost with the standard timing map is to minimise variables.
So, if the turbo is a good one for the engine and wouldn't cause a 'power band' from 4200 rpm then i've got the fueling wrong...

The thing is, you don't actually /know/ what timing it's running.
You might have the standard map in there, but maybe there is knock for some reason ( don't remember if that engine has a knock sensor)?

Or for example the incoming air is not being counted correctly for some reason, and it's off.
There can be a myriad of reasons. So if you are going to a standalone ECU - go all the way.

I'm just purchased the book you recomend, so there is some bed time reading for me when it arrives...!

Good, it's a great book, and it will help you understand tuning speed-density systems. Very useful to learn about megasquirt.

What would you think, more of less fuel 3000 to 4200 rpm?

I can't tell you. I need to be in the car, with headphones on, and all the logs and control with WBO2, to tell you. And then I might just as well map the thing.

Can you recomend anyone to tune properly?

I am afraid I can't. I am sure there's plenty of people who can dial in megasquirt well for you, but I can't give you a specific recommendation.

A good idea would be to dial in the VE and the timing map on a rolling road, because you can't find MBT for the low load states without a load bearing dyno with instantaneous torque output. Everything else you can do on the road.

I'd tune it for you if I was over in the UK right now, but sadly I am not.

[prj]

P.S.
When tuning you must understand why you make every change.
I don't want to do too much shameless promotion, and this material will in no way help with your otto engine, but you can read http://prj-tuning.com/?p=163 as a little example, of how in *my* opinion one should approach tuning.

[DaveT]

I'd tune it for you if I was over in the UK right now, but sadly I am not.

I'm probably gonna be a good few months reading and implementing timing control, I need to add some crank sensors & also got some body work to do. If your gonna be in the UK sometime in the next few months please let me know, I'll gladly flatter your palm with some folding beer vouchers in exchange for some tuning!!


Many thanks for everyone's help and advice, I know what I need to do now!!!

Dave

[adam g]

Ive been trying to map my own timing on an 034 efi system, even with a knock light and EGT gauge im not confident especially at high revs. Im now planning the rolling road route to be sure. Think ill invest in a copy of that book too.
One other thing, did they send the right turbo. Im sure they sent me a bigger one by mistake a few years back

[Jamo]

Thanks for your reply,

I understand that spark, fuel & boost are all related. That the main reason why i'm running standard boost with the standard timing map is to minimise variables.
So, if the turbo is a good one for the engine and wouldn't cause a 'power band' from 4200 rpm then i've got the fueling wrong...

I'm just purchased the book you recomend, so there is some bed time reading for me when it arrives...!

What would you think, more of less fuel 3000 to 4200 rpm?
Can you recomend anyone to tune properly?

Many thanks

Dave

Gunni at gs tuning