R34 2871R setup optimisation

[Bman1296]

Hello!

I am researching the most optimal setup for my current turbo in my R34 GT-T. It is a Garret T2871R (part number 446179-5032). It is inside a stock hi flowed R34 turbo housing, stock exhaust manifold, 3" dump pipe, hi flow cat, Fujitsubo muffler. I also have a return flow FMIC.

Currently my car is making 265rwkw at 17 PSI however I have boost dropoff to around 12-13 PSI by redline. I am looking to maintain this boost pressure at 17 PSI. Is there any way to do this? I am looking at buying 260 deg PonCams to help with boost response and exhaust flow (hopefully?)

I would like to make around 280-290rwkw without changing the turbo.

Any tips for optimising this setup? I have attached some dyno graphs.

Cheers

[GTSBoy]

This

26 minutes ago, Bman1296 said:

I have boost dropoff to around 12-13 PSI by redline

caused by this

26 minutes ago, Bman1296 said:

I also have a return flow FMIC.

It's a simple fix. And then add more boost.

[Bman1296]

2 hours ago, GTSBoy said:

This

caused by this

It's a simple fix. And then add more boost.

If contention/Bottleneck based in the return flow FMIC is the cause, how come it is possible to reach 17 PSI in the first place?

Edited April 24, 2021 by Bman1296

[Kinkstaah]

It is absolutely not the blitz FMIC. I have made 500kw through one, with no such drop off, running 24psi through a stroked motor.

How is your boost being controlled? If it is a manual controller then that boost drop off is *normal*.
If its electronic, are you certain it is at 100% duty cycle towards the end of the run?

If you want more flow out of the same turbo, in this situation your answer is letting it breathe better at higher RPM, and If it is, you need to consider running an external gate, or opening up the exhaust side of the turbo (i.e larger housing).

The veteran in me says "Enjoy 265kw and drive it long term and have fun with the car"

[GTSBoy]

17 psi at lower revs (and hence power output) = less air flow than 17 psi at higher revs (and hence power output).

Pressure drop goes up with the square of flow rate.

[GTSBoy]

2 minutes ago, Kinkstaah said:

It is absolutely not the blitz FMIC.

Do we know that it is a Blitz? OP just said "return flow".

[Kinkstaah]

It's true - We don't, but most return FMIC's that are easily accessible, for R34's are Blitz's. Which are more than enough, I've seen many a people ditch the return flow, or upgrade the core for no benefit at all.

Specifically people chasing boost drop off issues at high RPM, with both RB's and SR's. They were all internally gated and found that EWG's and better boost control instantly solved the problem of... boost control.

2871's and 3071's and all the IWG 3076's in the world have similar sort of problems to this. If OP is on 98 fuel this is a really solid result.

But without knowledge of the boost controller duty cycle noone really knows what's going on fully... Can only give reports of other things that have been known to work.

[Bman1296]

16 minutes ago, Kinkstaah said:

It's true - We don't, but most return FMIC's that are easily accessible, for R34's are Blitz's. Which are more than enough, I've seen many a people ditch the return flow, or upgrade the core for no benefit at all.

Specifically people chasing boost drop off issues at high RPM, with both RB's and SR's. They were all internally gated and found that EWG's and better boost control instantly solved the problem of... boost control.

2871's and 3071's and all the IWG 3076's in the world have similar sort of problems to this. If OP is on 98 fuel this is a really solid result.

But without knowledge of the boost controller duty cycle noone really knows what's going on fully... Can only give reports of other things that have been known to work.

Thanks! To answer a few of your questions, I am not sure what type of FMIC it is, I've honestly never really bothered to check. I'll go have a look now and edit this.

I am running on 98 pump fuel.

I've considered going EWG but that means new exhaust manifold, new oil lines to the turbo, new turbo... list goes on.

And I am using an ECB, Greddy Profec Spec B II. I'm not sure how to interpret its current settings in terms of duty cycle.

EDIT:
I have attached pictures of the FMIC. I could not see a single identifying mark on it, I looked all around on all sides. I do not expect anyone to know what it is from the photos. I am going with ebay branded!

Edited April 24, 2021 by Bman1296

[Kinkstaah]

19 minutes ago, Bman1296 said:

Thanks! To answer a few of your questions, I am not sure what type of FMIC it is, I've honestly never really bothered to check. I'll go have a look now and edit this.

I am running on 98 pump fuel.

I've considered going EWG but that means new exhaust manifold, new oil lines to the turbo, new turbo... list goes on.

And I am using an ECB, Greddy Profec Spec B II. I'm not sure how to interpret its current settings in terms of duty cycle.

Given it's a Hiflow Turbo on a stock manifold, I would be looking at some heavy duty actuators (if they exist, do Turbosmart make them? Can they be made to work) There were some pretty nifty dual port ones that did what they said on the Tin, and did all they could to keep that gate closed.

I don't think cams are really going to help much, I had the 260 poncams and figured they didn't do much in the real world back to back for spending the $. I think your money would be better spent on getting an EWG in there (which means manifold or turbo housing changes at the very least), and yeah at that point why not a GT3071? Or realistically, a G550? As you said the list goes on, and you're at a precipice where you'd need a lot of fab to 'fix' it. (Turbo, Manifold, Fabrication, injectors, internals? etc etc etc).

I also suspect the car is the way it is because it wants to look entirely stock. I've been there too, and had the same problem.

Sometimes people overthink things and think cars don't perform the way they 'should' They almost always perform the way they should. A high flowed OP6 with a 2871 with internal gate, on 98 will do exactly this.

For it to do anything different you're gonna have to change stuff. The actuator may get you a few more PSI but its worth noting that you're forcing it to happen, making more backpressure/heat in a small housing etc etc etc. Depending on what you want to use the car for, this could be a non issue or a big issue. You'd definitely hold your boost target if you weld it shut etc!

Sometimes these little sanity checks have uses.

(like staying on 98. E85 you will likely make your target power, but has its own considerations)

[Bman1296]

7 minutes ago, Kinkstaah said:

Given it's a Hiflow Turbo on a stock manifold, I would be looking at some heavy duty actuators (if they exist, do Turbosmart make them? Can they be made to work) There were some pretty nifty dual port ones that did what they said on the Tin, and did all they could to keep that gate closed.

I don't think cams are really going to help much, I had the 260 poncams and figured they didn't do much in the real world back to back for spending the $. I think your money would be better spent on getting an EWG in there (which means manifold or turbo housing changes at the very least), and yeah at that point why not a GT3071? Or realistically, a G550? As you said the list goes on, and you're at a precipice where you'd need a lot of fab to 'fix' it. (Turbo, Manifold, Fabrication, injectors, internals? etc etc etc).

I also suspect the car is the way it is because it wants to look entirely stock. I've been there too, and had the same problem.

Sometimes people overthink things and think cars don't perform the way they 'should' They almost always perform the way they should. A high flowed OP6 with a 2871 with internal gate, on 98 will do exactly this.

For it to do anything different you're gonna have to change stuff. The actuator may get you a few more PSI but its worth noting that you're forcing it to happen, making more backpressure/heat in a small housing etc etc etc. Depending on what you want to use the car for, this could be a non issue or a big issue. You'd definitely hold your boost target if you weld it shut etc!

Sometimes these little sanity checks have uses.

The cams I am going for a bit of lumpy idle (tuned that way hopefully! Sounds are important) and just to get a little bit extra power as I don't want to change the manifold and do EWG. The car looks stock and I'm trying to keep it like that, you're definitely right.

I think the car performs excellently as it is - if I changed turbo I would lose out on my responsiveness, full boost at 3k rpm. It is mostly street driven, but I wouldn't be against a track day just for a bit of fun.

My injectors are from an R35 GTR so I am fine on that end.

I'll look into the actuator. I am not as concerned about heat as I don't flog it when it is a hot day, and I have an double cell koyo radiator to assist. Oil cooler would be too much to work into my stock-ish setup, and kind of sticks out I assume.

Edited April 24, 2021 by Bman1296

[hypergear]

Blitz return flow and pretty much any return flow cooler kit and internal gate senario in my experience had a boost pressure drop problem. I replaced it with a proper FMIC and made pretty decent gain. 

Secondily,  GT28 turbine is on the small side for a Rb25det. I would go for a bigger size high flow, external gate, and a bigger PWR FMIC to make better power. The Camshaft in your case will not help. 

[Bman1296]

2 hours ago, hypergear said:

Blitz return flow and pretty much any return flow cooler kit and internal gate senario in my experience had a boost pressure drop problem. I replaced it with a proper FMIC and made pretty decent gain. 

Secondily,  GT28 turbine is on the small side for a Rb25det. I would go for a bigger size high flow, external gate, and a bigger PWR FMIC to make better power. The Camshaft in your case will not help. 

Thanks! I'll have a look into what is reasonable for my setup. Glad to know that is most likely the return flow and internal gate, as maintaining the higher PSI would be preferable.

[Dose Pipe Sutututu]

Bandaid solution, tap your pressure source after the intercooler for your EBC/boost solenoid.

This will work the turbo a bit harder but will provide you with a bit more boost stability.

Also return flows suck, I can guarantee you as soon as you replace that with a proper FMIC setup, with a decent core you'll instantly make more power.

[Kinkstaah]

21 hours ago, Bman1296 said:

The cams I am going for a bit of lumpy idle (tuned that way hopefully! Sounds are important) and just to get a little bit extra power as I don't want to change the manifold and do EWG. The car looks stock and I'm trying to keep it like that, you're definitely right.

I think the car performs excellently as it is - if I changed turbo I would lose out on my responsiveness, full boost at 3k rpm. It is mostly street driven, but I wouldn't be against a track day just for a bit of fun.

My injectors are from an R35 GTR so I am fine on that end.

I'll look into the actuator. I am not as concerned about heat as I don't flog it when it is a hot day, and I have an double cell koyo radiator to assist. Oil cooler would be too much to work into my stock-ish setup, and kind of sticks out I assume.

The actuator (and Dose's idea of putting the boost reference post-intercooler) can achieve similar things. Its worth noting that with a stronger spring, you may end up with say, 17psi at the end, but your likely peak will be 19-20 psi. You'll still get the dropoff, but the peak and end point will be higher.

To have it flat through the whole range you can't max out the IWG. You'd probably find if you try and run 7 psi it will suddenly not have this 'shape' to the boost curve.

I would be very surprised to see any change to a car before or after a return flow FMIC, back to back, when the core is the same size, and same internal design, with no other changes. Has anyone ever cut the end tank off a return flow FMIC, put on a new straight end tank on the same intercooler and done a test? If they have I haven't seen it....

But hey, if you do make a non return flow design it will fail the "It looks stock and uses stock holes" equation in your case.

Really to try and make the power without changing the core things that make the power (i.e the turbo) its going to be a series of small changes to get there. Having a track day car and a street car is very different so simply finding a way to add 'a little more boost' may just be enough in your scenario to do it. This is after all a pretty modest/reasonable goal so eking out the last 0.000001% theoretically on the internet shouldn't be required

[hypergear]

Older ATR43 prototype.  Katashi 600x300x100mm cooler with return flow piping VS 3inches FMIC piping. Nothing else has been changed on the car. 

 

 

I've tried different brands of return flow coolers kits including Greddy, Blitz, PWR, HKS, and normal FMIC with return flow piping. Nothing worked to expectations. Out of the lot as a complete off shelf return flow kit. HKS had the best performance. 

 

Edited April 25, 2021 by hypergear

[Bman1296]

5 hours ago, Kinkstaah said:

The actuator (and Dose's idea of putting the boost reference post-intercooler) can achieve similar things. Its worth noting that with a stronger spring, you may end up with say, 17psi at the end, but your likely peak will be 19-20 psi. You'll still get the dropoff, but the peak and end point will be higher.

To have it flat through the whole range you can't max out the IWG. You'd probably find if you try and run 7 psi it will suddenly not have this 'shape' to the boost curve.

I would be very surprised to see any change to a car before or after a return flow FMIC, back to back, when the core is the same size, and same internal design, with no other changes. Has anyone ever cut the end tank off a return flow FMIC, put on a new straight end tank on the same intercooler and done a test? If they have I haven't seen it....

But hey, if you do make a non return flow design it will fail the "It looks stock and uses stock holes" equation in your case.

Really to try and make the power without changing the core things that make the power (i.e the turbo) its going to be a series of small changes to get there. Having a track day car and a street car is very different so simply finding a way to add 'a little more boost' may just be enough in your scenario to do it. This is after all a pretty modest/reasonable goal so eking out the last 0.000001% theoretically on the internet shouldn't be required

I don’t think I’d like to compromise on the return flow so I’ll just keep that as it is. 
 

I might try the actuator trick one day. But yeah that’ll ruin my turbo faster due to the heat and extra stress. 
 

In the meantime im going to give 260° poncams a go, and change the tune to increase drivability.

[Dose Pipe Sutututu]

11 hours ago, Bman1296 said:

In the meantime im going to give 260° poncams a go, and change the tune to increase drivability.

This actually won't increase "driveability", you'll end up with a bit more lag. Also, 260 Poncams don't actually brap or anything like that.

You're better off with 264/272 Kelfords for brap.

[GTSBoy]

I thought the intent of the thread was "optimisaton" anyway.

[Ben C34]

Don't change cams mate . Complete waste of money on your setup

[Dose Pipe Sutututu]

Relocate boost source to post intercooler, pre throttle body. Add more duty cycle up top.