R6n350GT

iTrader: (1)

So short story 2003 VQ35DE 6MT with block HR mod done.

Engine rebuilt again with
Previous: forged pistons, rods, BC cams, BC cam springs
New: rev up oil pump, ARP L19 studs, Comtec Gasket, 1400cc black ops E85 injectors

Was making 500HP with T3 low mount GT35r .82 a/r at 15psi before new parts (had 1000cc, HR gasket and head bolts) (HKS ST kit i have but Treadstone 720HP same side intercooler)

All using CJM Stage 3 RFS

Now new tuner and at 15psi its at 430HP and upping to 17 psi is making no extra power.


QUESTION:
Is this possible to be valve float and BC springs have failed ?
what else can cause no extra power to be made if the below are all ok ?

tuner said it has to be as he has tested
- dump pipe pressure and intercooler pressure drop
- taken cat and exhaust off to remove the back pressure (was 6psi less with exhaust off, now at 2psi (was 8)..)
- ran the engine with the breathers completely off to eliminate the engine breathing (i read about the positive crank case pressure so i assume with them doing the above that is eliminated as the problem ?

OTHER ISSUES
Turbo before all of this was fine, now it has oil leak where is hot side is bolted onto CHRA and is blowing smoke after power run and getting worse. He initially thought because turbo was upside down when taken off the car some oil pooled in the housing but its not getting better..

- I read that too much crank case pressure can cause this but he ran with breathers off... and still and issue i think... ?


Thanks very much,
i need to know what to do next.
I have a Fujitsubo Legalis R exhaust btw
do i need better one, better turbo (6266 or 6466 or 6766 CEA)

thatv35guy

iTrader: (1)

Too much exhaust back pressure?

R6n350GT

iTrader: (1)

with exhaust and cat was 8psi of back pressure, without was 2psi - he tried tuning without and still no more power i think, ill have to double check.

but the car has been prior at 500 and now its stuck at 430

thatv35guy

iTrader: (1)

Is this on E85?

I believe the exhaust system itself shouldn't have too much to do with the actual exhaust pressure though (your cat might though), the turbo's exhaust housing would be the main culprit. When I was running a .82 exhaust housing on my car after about 470 whp any additional boost would not yield anymore hp, I'd get a rise in torque and exhaust back pressure, but no more hp. This was on a PL kit with a 35R turbo and 91 oct. pump gas.

Edit: Sorry, just saw that it was making 500 whp previously

Speednz

I read to the point where you said "other issues" and stated the turbo problems. That's kind of significant and would be listed under main problem, seems to me that the seals are bad and in need of a rebuild.. Journal, ball bearing or what kind of turbo? How's your oil pressure? I might have over read this information, but it was a long post. Where is your boost guage hooked up to? I'm assuming your manifold to meter manifold pressure. I wouldn't think twice to consider maybe it's the tuner? How are your AFRs?

Edit: Also the crank vent can play a big factor in the smoking. Is it orientated the same as before?

Jennifer 2

R6n350, if your tuner strongly suggests valve float why doesn’t he test for that directly. My dad used sensitive vacuum gauges to diagnose any number of high performance engine ailments. Excessive valve float will cause a distinctive oscillation on a quality vacuum gauge. After dad used any of his vacuum, manometer or pressure gauges he would call me to clean and replace them in the velvet-lined cases. There was always some talk of an orphanage if I ever dropped any of them.

If your tuner simply unhooked the charge pipe temporarily, and ran up the engine rpm with a proper vac gauge attached he should be able to confirm or rule out valve float.

Are you running some crazy high rpm? Otherwise why the thought that a matched cam and springs would suddenly create valve float?

R6n350GT

iTrader: (1)

This, based on 35r with .82 housing
http://www.digi-hardware.com/atr43exg.html

360 degrees Thrust bearing


I am overseas so cannot answer specific info re oil pressure, ARF ect but
- boost is hooked up to plenum post TB
- i dont know if they have tested the turbo shaft to see if any sloop but there was no issue with it previous and making 500hp

What do you mean by "Also the crank vent can play a big factor in the smoking. Is it orientated the same as before" ?

R6n350GT

iTrader: (1)

I do not know RPM as all the dyno sheets he sent never had RPM only speed
and i think he thought valve float as he tested with breathers off, intercooler pressure drop ....

How exactly can you see valve float with vac gauge attached to the TB while ramping up rpm ? I get frustrated as i cant call him, only email

R6n350GT

iTrader: (1)

yes i know the .82 is bit restrictive but it already made 500 and realstreetperformance who sells precision 6277 said on T3 and .82 there is no reason for that turbo not to get 600-800 like many others have done..

so yeah its so frustrating.. I have HKS manafolds by the way from the ST HKS turbo kit not stock.. but i changed the T2 3037 that came with it to T3 35r .82

WTFMike

iTrader: (2)

The .82 is far too restrictive to make 600-800hp on a 3.5 liter motor. I too am using a gt35r. However, I'm using the 1.06 turbine housing. When I was doing research prior to my build, I never ran across any other VQ35 builds that made 600-800 with a single gt35r using a .82 turbine housing.

Jennifer 2

Valve float is a mechanical phenomenon that will repeat at a given RPM. If you temporarily remove the charge pipe so that the engine will revert back to running as naturally aspirated you can hook a vacuum gauge into the intake plenum using an existing fitting. Every NA engine will maintain a lower pressure in the plenum than atmospheric pressure. A sensitive gauge will read the amount of vacuum contingent with throttle position and rpm. This can be extrapolated to how smooth the air is flowing. If valve float occurs, the gauge will oscillate in a certain pattern. An experienced tuner/mechanic can easily decipher this and some other ailments.

rcdash

iTrader: (18)

Not valve float if it's making power at lower psi up to 15 psi. I've never heard of BC springs failing. If your tuner is suggesting that at reasonable rpms, then you need to find a new tuner. A low compression motor is going to make slightly less power at the same boost level. That is normal. You may have been at the limit at 500 whp with your turbine side flow with the stock motor. Please don't tell me you had the engine built and are using stock headers?

If oil leaking from turbo then something wrong - scavenging not working, seals blown, too much oil pressure, return line kinked, etc. Fix this first. Good thought to just put breathers on the valve covers.

Remove exhaust (maybe a turn down if near fuel lines, etc) and do a pull because that is easy.

Speednz

#1 cause of oil leakage from turbo seals are from excess engine crank case pressure. If you don't believe me, believe my turbonetics manual.

dboyzalter

iTrader: (3)

Is it the same dyno and shop that you went too when you made 500hp? The last shop might have had a more generous system. Thats the only idea I have best of luck wish my car made 400hp

R6n350GT

iTrader: (1)

No different

Here is his reply "

I have done multiple runs with breathers off. the turbo is hurt mate! This could be from bearing material going through the turbo when engine was hurt mate! The engine is perfect. It needs valve springs I have been through this **** too many times with heaps of other engines and troy told me he explained to you why it happens, the data is there in front of your eyes"

Ok rcdash, i also find it hard to believe its the springs. the exhaust has been taken off at the cat for a run and no extra power, just spooled fasted due to less back pressure. Also i am using HKS manafolds with cross over pipe.

pics are here of kit but keep in mind, T2 -> T3, 3037 -> 35r , SMIC to treadstone 720HP FMIC

http://www.zclub.org.nz/viewtopic.ph...0e9afc53f4048b

R6n350GT

iTrader: (1)

oh also car was at 500hp not on stock engine but built already.
Was rebuilt as it overheaded due to coolant leak while i was in stop start traffic on highway. It was stuck at 500hp as old tuner said injectors maxed out .

SO i thought well better check everything in the rebuild since it over heated, get new oil pump, 1400cc injectors, comtec gasket, L19 head studs (had HR before) and then ramp up the boost.

Mechanic used wrong size bearings. .025 instead of .25 or maybe other way around.. anyway knocking noise occurred and engine was stripped down again and new mechanic was used to completely do it all over again, new crank shaft, block, serviced the heads (but didnt check springs....)

R6n350GT

iTrader: (1)

Yes i agree. The stock manifolds and the T3 .82 did not make more than 450HP regardless of PSI using E85 on Dyno Dynamics.

Even with the 1.06 the HKS design of manifolds and T3 i dont think i would get much more HP. I ended up having the tuner put it at 15psi and 425HP as prior higher levels required so much duty cycle and car didnt like it.


I asked about this and they had no idea how to do it..

Not stock headers but HKS headers which are just as bad. they are all merged into a 1.64" runner, not even 3:1.... they then have small collectors also.

I went to shop to look at turbo, the HKS kit mounts the turbo above oil pan so a hose returns oil via gravity but the angle is not very steep. Well i felt the hose and it was kinked.. so i got a 90 degree brass fitting

Also drilled out PCV, breather on it and plugged off plenum return. = no more smoking turbo.

So now ripping kit off and doing boosted performance style kit with 6466 T4 TS 1.32 a/r

ogiehooker

Dat kitty sho du beez smart!

rcdash

iTrader: (18)

Turbo return line then? Glad you found it.

iideadeyeii

iTrader: (6)

Different tuners? A much retarded timing could lose you that much power.

I've been told I'm losing 30+whp (sitting at 295 boosted) because my timing is pulled about 8 degrees too much.