2835pros Boost Loss Ideas Wanted

[grepin]

Hi all.

I have noticed a few 2835ProS turbos getting around now and am wondering if anyone has had the wastegate being pushed open.

I have extensive mods including GTr cams, exh manifold, plenum, large throttlebody etc etc. My issue is that at 6000rpm my wastegate is being pushed open. I have tried the tightest spring tension I can, even to the point that it can make 20psi on spring alone (still opening). I have tried dual chamber wastegates with nothing working. The car has made 300rwkw at 22psi so turbo has easily reached its potential. With the wastegate opening at 6000rpm noticeable on the power curve.

I am now thinking that the 0.67 ar exh housing may be too small for the flow I am getting.

These turbos do come with a 0.87 housing so may be the go if I can find one. Does anyone want to swap?

Any more thoughts would help.

Cheeers

Edited February 1, 2006 by grepin

[gtst25]

Are you sure the gate is opening? Mine drops off boost to about 16 psi in the top end but I thought it was just running out of puff so to speak?

Great power figure though - 45rwkw more than me!

Stock unopened engine for me though.

Cheers

[grepin]

Are you sure the gate is opening? Mine drops off boost to about 16 psi in the top end but I thought it was just running out of puff so to speak?

Great power figure though - 45rwkw more than me!

Stock unopened engine for me though.

Cheers

<{POST_SNAPBACK}>

Yeah I have actually watched it happen on the dyno.

It opens initially as the pressure becomes too great then will close a little after it looses some pressure and power curve will rise. It drops off as most turbos do in the upper rev range. With the standard 15psi actuator it is real bad, like 20kw drop at 6000rpm compared to a 20psi actuator I use with extra spring. Only problem is it still opens and restricts me to running 20+psi. Plus I seem to get detonation at the point it releases boost at 6000rpm. Might be just noise from the actuator as is detonation registered on the PFC HC and not audible.

Edited February 1, 2006 by grepin

[Robo's]

Is the turbo reached its maximum point?

[infected flow]

Is the turbo reached its maximum point?

<{POST_SNAPBACK}>

NO THESE ARE GOOD FOR 25-27PSI

[Roy]

How do you know?

Being good for a certain boost doesnt tell you much does it? Im pretty sure just about any turbo is good for 45psi if you want to wind that much boost into an engine.

Where they stop makign power, adn how efficient they are at a certain shaft speed deems whether its worhtwhile running that much boost

[gtst25]

I DOUBT THESE ARE GOOD FOR 25 - 27 PSI.

I'M SURE THERE'S ROOM FOR IMPROVEMENT WITH MY SET UP!

GREPIN ARE YOU RUNNING A STANDARD BOTTOM END/COMPRESSION RATIO?

AT WHAT RPM ARE YOU MAKING THIS 22PSI?

ARE YOU RUNNING THE APEXI BOOST CONTROL KIT?

MINE REALLY TAKES OFF AT AROUND 4000 RPM, BUT CAN'T HOLD MORE THAN ABOUT 16 PSI UP THE TOP END.

REALLY INTERESTED IN YOUR SET UP - GREAT POWER - I WONDER HOW THINGS WOULD GO FOR ME WITH THE BIGGEST PON CAMS POSSIBLE (HYDRAULIC) AND AN OIL CATCH CAN?

CHEERS!

Edited February 2, 2006 by gtst25

[grepin]

I DOUBT THESE ARE GOOD FOR 25 - 27 PSI.

I'M SURE THERE'S ROOM FOR IMPROVEMENT WITH MY SET UP!

GREPIN ARE YOU RUNNING A STANDARD BOTTOM END/COMPRESSION RATIO?

AT WHAT RPM ARE YOU MAKING THIS 22PSI?

ARE YOU RUNNING THE APEXI BOOST CONTROL KIT?

MINE REALLY TAKES OFF AT AROUND 4000 RPM, BUT CAN'T HOLD MORE THAN ABOUT 16 PSI UP THE TOP END.

REALLY INTERESTED IN YOUR SET UP - GREAT POWER - I WONDER HOW THINGS WOULD GO FOR ME WITH THE BIGGEST PON CAMS POSSIBLE (HYDRAULIC) AND AN OIL CATCH CAN?

CHEERS!

<{POST_SNAPBACK}>

Yeah I have a standard bottom end. The head has been lightly ported with HKS GTR 256 cams. SR20 exh valves from memory. Solid lifters etc. CAM gears. Greddy plenum with Q45 throttle boddy and custom exh manifold. All this was done after I had the turbo so might be a little too much flow/demond on the turbo. That said it has made 312rwkw on a couple of different dynos.

I do run the Apexi boost kit which was second hand so I may consider something else like maybe the e-boost.

To be honest I would just stick to maybe pon cams, maybe exh manifold (proven one there can be some dodgy ones). Or stick with standard gear if its making the power. A lot of money can be spent on little gains.

My head only ended up the way it has because I had the cams given to me. However cost more than I thought to set up. Will be a killer on a 3L motor however.

22Psi at around 6800rpm and drops off to 16psi at 7500rpm.

I have decided to go the 0.87 housing and see how that goes.

[gtst25]

Yeah I have a standard bottom end. The head has been lightly ported with HKS GTR 256 cams. SR20 exh valves from memory. Solid lifters etc. CAM gears. Greddy plenum with Q45 throttle boddy and custom exh manifold. All this was done after I had the turbo so might be a little too much flow/demond on the turbo. That said it has made 312rwkw on a couple of different dynos.

I do run the Apexi boost kit which was second hand so I may consider  something else like maybe the e-boost.

To be honest I would just stick to maybe pon cams, maybe exh manifold (proven one there can be some dodgy ones). Or stick with standard gear if its making the power. A lot of money can be spent on little gains.

My head only ended up the way it has because I had the cams given to me. However cost more than I thought to set up. Will be a killer on a 3L motor however.

22Psi at around 6800rpm and drops off to 16psi at 7500rpm.

I have decided to go the 0.87 housing and see how that goes.

<{POST_SNAPBACK}>

I'll be keenly interested in seeing how it goes with the larger exhaust housing!

Slyr33 is running the same turbo and making about 287rwkw with a built bottom end - I'm surprised your're maing over 300 with the standard compression ratio (even though cams can change this)

Mine definately drops boost earlier than you - there probably would be a gain in changing my wastegate spring too.

I've also thought hard about a 3litre - it would get rid of the loss of torque that's for sure!

I take it that you're using the standard exhaust manifold?

Another couple of questions:

What ignition timing are you using at the highest load point you are hitting? I'm at 17 degrees at load point 16.

Are you using the HKS dump that comes with the turbo kit?

Cheers

[grepin]

I'll be keenly interested in seeing how it goes with the larger exhaust housing!

Slyr33 is running the same turbo and making about 287rwkw with a built bottom end - I'm surprised your're maing over 300 with the standard compression ratio (even though cams can change this)

Mine definately drops boost earlier than you - there probably would be a gain in changing my wastegate spring too.

I've also thought hard about a 3litre - it would get rid of the loss of torque that's for sure!

I take it that you're using the standard exhaust manifold?

Another couple of questions:

What ignition timing are you using at the highest load point you are hitting? I'm at 17 degrees at load point 16.

Are you using the HKS dump that comes with the turbo kit?

Cheers

<{POST_SNAPBACK}>

No I have a aftermarket exhaust manifold.

I havent been near my car for 3.5 months as am overseas with the Defence Force, however from memory it was around the 16 deg on the PFC. Now this is not always exactly accurate as it depends on the base timing under the bonnet.

I had this turbo before anyone else that could be read about on these forums. There were no kits readily available then, well on Greenline anyway so I had one made. Funnily it is pretty close to the kit item.

I get home mid next week and have pics of this stuff if you want to PM your email.

I think I have posted dyno results a long time ago. I will have a search for a link.