My 3B Coupe project - Total rebuild

[s2martyn]

this all sounds familiar to me...wastegate sounds like its sticking(same as mine was)
it only gives your chosen boost level at high rpm

[AndyP]

What about the waste gate then could that be leaking boost .

Always a possibility, but it wouldn't explain why it does boost at higher revs. I'm going to leak test it again on Wednesday anyway.

I took Bry for a spin in it the other night and he though it was as quick as yours, but just lacking that mid range.

[T2Andy]

What about the waste gate then could that be leaking boost .

[A80Avant]

No, it won't.

That said, what's the CR on your engine Andy?

ok, if you say so...

[AndyP]

Andy I was wondering after I spoke to you today why you are running only 1.4 bar ,are you going to have a more aggressive map later on mine was running 1.7 bar which gave a real good kick as you know ,surely it's the map that is making it boost later on ,mine ran very differently when using different chips/maps from steady to aggressive on the Mtm one ,the first one needed revs before it did anything if you remember ,hope you sort her after all the effort or swap it for a ko4ed S4

Yours was mapped on the N75 for which you can tune different boost characteristics, when you map on spring, if you've got the throttle wide open and the wastegate is shut, then it should boost and mine doesn't, hence me thinking that there could still be a problem with the turbo

[AndyP]

Uhm, where it was mapped at?
0.82 A/R 3071R is a good choice, on a stroker it spools even a bit better than RS2 turbo and it is capable of over 450hp crank.

And I don't see why the decision to run "xxx" boost. You just boost until it stops making power, be that due to hotside or coldside (or better to say exhaust or intake).
This turbo easily runs 1.9 bar and 1.7 to 7200 rpm on stock engine.

EDIT:
Just checked logs, 1.9 bar @ 3800 rpm in 3rd, stock turbo does 1.6 @ 3300, K26/K27 does 1.9 @ 3900

It was mapped by Mark Hardy ( Automark ) and was mapped on a spring hence the reason for choosing boost level, you have a limited supply of springs. I know mapping on a spring it not to everybody's choosing but I'm fully aware of the risks involved. My previous engine was mapped on a spring and I like the power delivery it gives, hence the reason for choosing this route.

[AndyP]

No, it won't.

That said, what's the CR on your engine Andy?

It's hard to say for certain because I'm not sure witch part of the build is causing it to be high. It was specc'd to be 9.0:1 but calculating back from the compression test results ( 200psi ) indicate it's around 9.5:1. Mark was using the reference of a good Golf GTi 16v engine giving similar compression figures and that has a CR of 10:1.

[prj]

Compression being very high could be a limitation to your highest boost curve, but the engine should produce equal power with less boost.

No, it won't.

That said, what's the CR on your engine Andy?

[Ross]

Andy,

Glad to hear you are up and running with the car but you should be another 100hp on your estimate 'low 300s'...

Even on my 'automark' mapped Avant with the GT3071 boost was coming in alot earlier than that. Remember I was running the engine in, but hitting 3k rpm it was very hard not to get it boosting - even on mid throttle it would start coming in agressively and I'd jump off hte throttle... my honest opinion -it wasn't to my taste, and it would have been into MRC as soon as run in. But that is kinda the opposite to the problem you're having

Pretty much as PRJ said, on my coupe I was seeing 1.7bar at the redline set @ 7400rpm and full boost between 3500-3800 depending on gear (5 speed so 4th was more like 5th remember...)

Ross

[A80Avant]

i had 2.2bar on 3800 on the 3071 3d gear BUT, 0.63AR on VEMS. On 4th it was around 3650 for the same boost.

Andy, i think its down to the current map setup. Once you get to MRC you'll have it done properly. Compression being very high could be a limitation to your highest boost curve, but the engine should produce equal power with less boost.

[prj]

Look what I found:

2nd:


3rd:


Motronic data is slightly delayed from WBO2 and Boost data, offset can be seen towards end.

[T2Andy]

Andy I was wondering after I spoke to you today why you are running only 1.4 bar ,are you going to have a more aggressive map later on mine was running 1.7 bar which gave a real good kick as you know ,surely it's the map that is making it boost later on ,mine ran very differently when using different chips/maps from steady to aggressive on the Mtm one ,the first one needed revs before it did anything if you remember ,hope you sort her after all the effort or swap it for a ko4ed S4

[prj]

Uhm, where it was mapped at?
0.82 A/R 3071R is a good choice, on a stroker it spools even a bit better than RS2 turbo and it is capable of over 450hp crank.

And I don't see why the decision to run "xxx" boost. You just boost until it stops making power, be that due to hotside or coldside (or better to say exhaust or intake).
This turbo easily runs 1.9 bar and 1.7 to 7200 rpm on stock engine.

EDIT:
Just checked logs, 1.9 bar @ 3800 rpm in 3rd, stock turbo does 1.6 @ 3300, K26/K27 does 1.9 @ 3900

[AndyP]

Well it looks like I’ve finally got the breather system sorted out. After the car was mapped I found I was getting large amounts of oil in the inlet pipework so I decided to upgrade to a swirl pot and catch tank



I got the swirl pot from Andy Casey ( thanks again Andy ) and I was intending to swap to an ABY fuel rail so I could bolt the swirl pot to the earth points on the inlet manifold. This didn’t work as the FPR hits the manifold, likewise I couldn’t fit the ABY manifold because it hit the distributor.
So I ended up ditching the carbon canister and fitting both swirl pot and catch tank behind the fan. The layout is based on this design that JP posted



The only difference is that Andy’s swirl pot uses a 30mm hose from the ‘darleks head’ on the side of the block. I also changed the fitting on the back of the cam cover to a 16mm pipe and added an internal baffle to stop it dragging oil into the system under hard acceleration. I’ve only done about 35miles today and so far the inlet is staying dry.



Now onto the performance, so far this is disappointing to say the least. Because of the issues with the compression ratio being too high and the possibility that the knock sensors were not going to work on the TDi block it was decided to keep boost to around 1.5bar. We fitted a 1.5bar spring and back the preload adjuster all the way out, which give 1.4bar. The problem is with the way the turbo builds boost, from 2000rpm on WOT it starts at about 0.8bar then at 3000rpm it’s up to 1.0bar which it hold until 5000rpm when it jumps to 1.4bar. Between 5 and 7000rpm it holds 1.4bar and to be fair, is quite quick, although my butt dyno says it’s only low 300’s.
The whole point of going for the stroker engine with a relatively small turbo was to get an early spool and a really strong mid range and this is the opposite of what I’ve got. The map is set to be safe so it’s running a rich and has very little timing but I don’t think this would affect the boost delivery, I suspect there may still be a problem with the turbo. I've been reading Ross's thread when he put a 3071 on his old coupe and he was getting 1.5bar @ 3000rpm, and that was on a 2.2 with std head. The only difference was he had the 0.63A/R hot side and I've got the 0.82A/R, how much difference would that make? Not the 2000rpm I'm see I suspect.

I’ll be at MRC next Saturday so it will be available for test rides and hopefully somebody can point me in the right direction as to what’s wrong with it.

[Error404]

Excellent
Glad its back up and running Andy, so much work has gone into it now hopefully you can just drive it