2860r-5 Turbo Shuffle

[xcye]

Hi Charlie, we did disconnect the BoV and it doesn't change the behaviour. We put it on the Dyno today and vacuum tested the BoV and wastegate lines and everything is good and the wastegates activate at the same time and when it is shuffling the BoV remains closed as far as I know. Everything I have read indicates it is the backpressure from the FMIC causing the compressor stall on the turbo with the lower exhaust pressure. Changing to a dual inlet improved the situation a little, but it's still there.

Hi, Doug:
I could be wrong. But, I do not think that was turbo shuffling, as the sound you heard only happens on partial throttle. It was more like your compressors pushed too much air than needed at that point, which backed out and caused the Compressors to stall.

I noticed you had only one BOV installed there.
It seemed that the single HKS BOV did not open soon (or big) enough to let air out, which, in turn, stalled the compressors. Can you put back the stock BOVs to try?

[DougTaylor]

yo dude... your graph only shows 430 hp.... not 500 BHP! theres a huge difference.... orrrr did u post the wrong graph?

You are right - my graph shows whp, which I thought would be about 20% less than bhp - or did I get my acronyms mixed up?

[DougTaylor]

what!?!? 500hp at 14psi? that's nuckin futs, must be on race gas and stoic? I had 302whp on an uber rich tuner with -5s at 1 bar...

Actually, that's 91 octane and what it does every day. Notice the a/f is 13.3 too - I have an hks fcon pro-v and someone that really knows how to tune it. I also have 1000cc injectors, an upgraded ignition system, tomei poncam-b cams ... I just said I hadn't done anything to the 'bottom' end..

[DougTaylor]

Hi, Doug:
I could be wrong. But, I do not think that was turbo shuffling, as the sound you heard only happens on partial throttle. It was more like your compressors pushed too much air than needed at that point, which backed out and caused the Compressors to stall.

I noticed you had only one BOV installed there.
It seemed that the single HKS BOV did not open soon (or big) enough to let air out, which, in turn, stalled the compressors. Can you put back the stock BOVs to try?

OK Charlie - you win the prize for the most interesting advice yet - one of the guys working on the car and I had a discussion about the BoV spring/strength/timing, but we didn't get to your conclusion. That's a very good idea. I can't replace the stock BoVs as all the piping has changed, but maybe we can change the behavior of the BoV to let some of that pressure out. The other thing i could do maybe is remove the BoV downstream of the intercooler and replace it with 2 BoVs upstream of the IC - one in each pipe from the turbos? What do you think?

[JNS Performance]

Kind of off topic Doug, but did you notice a difference between the twin entry GReddy and the Autobahn88 intercooler? Power, response etc..

I assume you made 430whp without touching the cam gears? I know how Reg doesn't like playing with timing.

NismoS-tune: At 1 bar my car made 430whp on a mustang dyno with -5 turbos, 302whp? Your timing must of had like 2 degrees of advance, hehe. The first dyno run we did to make power yielded 280whp then we increased timing 1 degree and the power went to 320whp, another degree I made 360whp. Every degree we added made 40whp at the beginning then on the last degree the tuner added I made 8whp and he said it was a good place to stop and start playing with boost. 302whp is really really low, that was an uber safe tune. You can also make like 20-40whp just with playing with AFR's.

[xcye]

Hi, Doug:
First, I would try the stock BOVs (Vent to Atmosphere) to find out if the problem is with the HKS BOV.
Second, if you are not concerning with the cost, try to replace the HKS with a Synapse BOV with HKS flange. It seems (Based on information from WEB, not my own experience) the Synapse is a better BOV than HKS and it should opens sooner than HKS. And it will be blot on process instead of welding on more BOVs.

[DougTaylor]

Kind of off topic Doug, but did you notice a difference between the twin entry GReddy and the Autobahn88 intercooler? Power, response etc..

I assume you made 430whp without touching the cam gears? I know how Reg doesn't like playing with timing.

You are right Braden, the cam gears are at 0 as far as I recall. I haven't run it hard with the twin entry yet, and probably won't until the spring tune. Just driving it on the street with the odd pull feels pretty similar between the two but I'll let you know. I thinkg the true test will be to compare the dyno curves between the two.

[DougTaylor]

Hi, Doug:
First, I would try the stock BOVs (Vent to Atmosphere) to find out if the problem is with the HKS BOV.
Second, if you are not concerning with the cost, try to replace the HKS with a Synapse BOV with HKS flange. It seems (Based on information from WEB, not my own experience) the Synapse is a better BOV than HKS and it should opens sooner than HKS. And it will be blot on process instead of welding on more BOVs.

I just had a look at http://forums.gtrcanada.com/gt-r-pro...-kit-rb26.html and it looks like you might be on to something. I asked the guys there if anyone is running 2860r-5s.. But, compared to the $4000 price for the hks manifold with the balance pipe, the new bov is cheap! I'll either try your suggestion or talk to rcts about creating a controlled boost leak to reduce the boost pressure. That's the way I think it 'should' work anyways - maximum pressure at the manifold but no backpressure at the turbo outlets.

[NismoS-tune]

I just had a look at http://forums.gtrcanada.com/gt-r-pro...-kit-rb26.html and it looks like you might be on to something. I asked the guys there if anyone is running 2860r-5s.. But, compared to the $4000 price for the hks manifold with the balance pipe, the new bov is cheap! I'll either try your suggestion or talk to rcts about creating a controlled boost leak to reduce the boost pressure. That's the way I think it 'should' work anyways - maximum pressure at the manifold but no backpressure at the turbo outlets.

HKS manifold is not a fix to your problem compared to a twin entry IC... HKS BOV is fast but synapse is faster, just no readily available kits like HKS but you can get someone to weld it in for you

[xcye]

Hi, Doug:
Check this out

[GTR-Dad]

Here's a bit of reading on the shuffle topic.

http://forums.gtrcanada.com/gt-r-discussion/25286-2860r-5s-shuffle-engine-breaking.html

http://forums.gtrcanada.com/gt-r-discussion/22835-last-question-nobody-seems-know-whats-going.html

GL
Dan

[DougTaylor]

Thanks Charlie, some good news about the Synapse in there..

Hi, Doug:
Check this out

[DougTaylor]

Thanks for taking the time to track that down for me Dan. I've ben focused on the balance tube on the exhaust manifolds, but this references a balance tube in the turbo inlet piping. This is something I don't have as my piping has all been replaced. Do you have an inlet balance tube and does it help? After reading this, it sounds like what am getting is very mild compared to what it could be. My car isn't bucking or anything, it's just a little noisy. I suspect with the HKS FCON ProV I have, the fuel issues are tuned out. Maybe I'm lucky and should just enjoy the noise..

Here's a bit of reading on the shuffle topic.

http://forums.gtrcanada.com/gt-r-discussion/25286-2860r-5s-shuffle-engine-breaking.html

http://forums.gtrcanada.com/gt-r-discussion/22835-last-question-nobody-seems-know-whats-going.html

GL
Dan

[GTR-Dad]

Doug,
When I was running with a Power FC and MAF's I experienced inlet air oscillation between the two turbos. Because the transfer function of the MAF is nonlinear, increasing the airflow through one and decreasing the flow through the other messed up fueling, which in turn seemed to increase the instability at the transition of vac to boost. (Idle was also terrible.)
Adding the balance tube between the inlet tracts between the MAF's and the turbos reduced the problem, but did not eliminate it. Swapping to a ViPEC speed density (MAP) system helped even more. You could still hear the onset of shuffle, but the MAP was not affected the way the MAF's were and it didn't feed on itself the way it used to. A season or two later I swapped out a turbo that was leaking some oil and the 'shuffle' dropped off even more.
If you're only getting some noise and it doesn't affect drivability, I wouldn't worry about it.
GL,
Dan

[DougTaylor]

Just thought I would share - late last year I picked up an HKS exhaust manifold, with a balance tube - which equalizes the exhaust pressure to both turbos, eliminating the shuffle. Now the really good news - got the car tuned and dyno'd yesterday and the balance tube had a great side effect - went from 435 whp to 497 whp - at approximately the same boost pressure - about 17 psi..