Rb25/30Det

[R32Abuser]

Hi all,

So I have come to the culmination of my build and have hit a brick wall. Before I run through the problem, here is the spec. list:

Parts

R32 RB25DE head

RB30 Series 2 bottom end

RB26/30 CP Pistons 9:1 Static CR (CP pins, rings etc.)

Spool RB30 Rods to suit. ARP fasteners

ACL Race series bearings to suit above rods

Standard Crank. Blueprinted/Balanced/Crack tested etc

RB25DET Series II Oil Pump with extended drive "Snout" (Spool Imports)

GT3076R 0.82 A/R Internal Wastgate Garret Turbocharger (Standard oil/water lines)

Standard exhaust manifold

Stiffer valve springs (unsure of brand)

High Energy Style Sump + Head drain (big f**k off fitting on the back of the head)

Standard valve train (Cams/gears/lifters etc)

Cometic Head gasket (Spool Imports)

GTR Waterpump

550cc Bosch EV14 Injectors

Nismo Fuel Reg (Adj.)

Nismo Engine Mounts/G-Box Mounts

Bosch 040 Fuel Pump

Nistune ECU Remap

Labour

Bore/Hone Block to suit CP Pistons

Deck Block

Grind/Blueprint Crankshaft

Balance Pistons

Micropolish Crankshaft

Balance Motor

Reconditioned Head

Modify/Weld/Machine Head

There is probably stuff I have left out but anyway onto the problem...

So it came to tuning the motor up today.

Car goes on the dyno, normal procedure run-in etc. Tune up starts, and the tuner finds a problem.

No matter what he did, he could put more than about 8 degrees worth of timing advance in the motor until it would knock/ping/detonate. Generally I was told that 20 degrees is about right for these motors.

Now there was several suggestions at this point:

1. Fuel - dropped the fuel in the tank. Replaced with 98 Octane BP Ultimate. Made no difference.

2. Faulty CAS/Timing sensor - Apparently nothing seems funky on this end of the spectrum so isn't something they think is wrong.

3. Static CR is too high - Pending a compression test (being done tomorrow).

4. Timing - Possibly the timing is out a tooth or two. Will check after the compression test.

Is there anything else every one can suggest?

With regards to the Stactic CR - I purchased these items from Spool Imports. They were quoted as the 9:1 CR Pistons alot of guys off here have used time and time again without any hassles. The only issue I see here is if the machinist as stuffed up somewhere and hasn't machined to suit the CP pistons. Has anyone else on here had any problems regarding these pistons? Is there anything anyone can suggest with regards to this portion of the build?

All help will be greatly appreciated!

Cheers,

David

Edited July 15, 2011 by R32Abuser

[Rolls]

What cams are in it? I've been told that I think it was 25de and det cams are the same overlap + lift etc, but one is offset by a couple of degrees and they usually dial it in with adjustable gears if using in a different motor.

I can't remember what the cams were that people were talking about, though when I was looking for a replacement exhaust one for my motor someone mentioned that, I'll see if I can dig up the reference.

[Bl4cK32]

From memory hes using GTR cams with a custom regrind.

Rb20 vs 25de(ones Im using)

RB20DET specs are: in: 240deg, 7.8mm ex: 240deg 7.8mm

RB25DE (R32): in: 240deg 7.8mm ex: 232deg 7.3mm

[Rolls]

He hasn't reground them yet, that was the plan eventually however.

Fairly sure he is using the rb25de cams, but not sure.

[Simon-S14]

sounds timing related.. being an RB30 did you follow the guide for the timing belt correctly? the cam gears on the dots with crank at TDC?

start with the basics

[R32Abuser]

Using the R32 RB25DE standard cams. Standard spec.

Timing belt was done in the position as per the RB30DOHC guide to my knowledge. Builder had the guide, and I told him many times to do the build as per the pdf.

I did not set the timing. That will also be a point of contention to look at. Haven't got the compression test results back yet, will update as soon as I know.

Builder is going back to the basics from what I have been told.

I said the same thing tho, sounds timing based but not too sure...

[Cubes]

What power was it making even though you only saw 8degree's ignition timing?

Mine with the std RB25DE cams was very much knife edge - it 'really' wanted to ping easily.

RB25DE cams really aren't much chop, their specs are not ideal for turbo app.

When the Tighe 805c cams went in I could dial in the boost and push some decent timing in to it resulting in a touch over 300rwkw before it had boost drop issues due to the soft wastegate spring.

A few things to start with...

• Ensure the CAS is ok - shove a timing light on her as you bring rev's up to ensure its not swaying timing as rpm increase, a faulty cas will cause det issues. (Darren I remember yours had this issue)
  
• Double check the cam timing
  
• You have a std exhaust manifold - The std exh manifold is T3 divided. t3 divided is larger than the single inlet of t3 gt30/gt35 inlet. Ensure you rip the exh. housing off and port match it to the t3 divided gasket. Don't think its ok to have that ridge there, it kills power.
  
• Are you still running the std inlet manifold/plenum? I port matched the inlet manifold to the plenum as there was also 'some' runners that were out by a good 3-5mm. Substantial IMO to have some runners that are fine and others that are extremely poor.
  

I've attached how much meat needs to be taken out of the exhaust housings inlet to match the outlet of the std exhaust manifold.

rbman with his gt35 on the std exhaust manifold (rb30det) did some porting to the inlet of his turbo after it was just not making power and hitting that det wall. He picked up around 25rwkw on the same boost from memory.

Hope that helps.

[R32Abuser]

Joel,

I dont know whether you remember, but the turbo on this build is your old GT30 turbo off your RB30

"What power was it making even though you only saw 8degree's ignition timing?"

Car made 207RWKW on the 8 degrees worth of timing. Got to drive it to the assemblers - Im in love

"Mine with the std RB25DE cams was very much knife edge - it 'really' wanted to ping easily. RB25DE cams really aren't much chop, their specs are not ideal for turbo app."

This may be one, if not the issue! But at only 8 degrees?

"Ensure the CAS is ok - shove a timing light on her as you bring rev's up to ensure its not swaying timing as rpm increase, a faulty cas will cause det issues. (Darren I remember yours had this issue)"

This will be checked subsequent to the compression test. Still though, I really doubt its the pistons and am hoping its simply just a timing issue.

"You have a std exhaust manifold - The std exh manifold is T3 divided. t3 divided is larger than the single inlet of t3 gt30/gt35 inlet. Ensure you rip the exh. housing off and port match it to the t3 divided gasket. Don't think its ok to have that ridge there, it kills power."

Did you do this to the exhaust housing on your old GT3076R? I can see it would hamper the flow considerably!

Are you still running the std inlet manifold/plenum? I port matched the inlet manifold to the plenum as there was also 'some' runners that were out by a good 3-5mm. Substantial IMO to have some runners that are fine and others that are extremely poor.

Yes. Still running standard inlet manifold/plenum. I would have thought that the engine builder/assembler would have picked this up and mentioned it if there was an issue. Ill be doing this aswell if that is the case.

Theres not alot I can do at the moment due to it being the weekend. However, hopefully more information comes about in the coming week. Joel, if you dont have a problem with it, Ill contact you via the email address I have when I bought your old turbo off you. Just want to run a few things by you regarding these issues!

Edited July 17, 2011 by R32Abuser

[Bl4cK32]

A few things to start with...

• Ensure the CAS is ok - shove a timing light on her as you bring rev's up to ensure its not swaying timing as rpm increase, a faulty cas will cause det issues. (Darren I remember yours had this issue)
  

yer, shaun had to either swap or rebuild my cas to get it working...cant remember, but he sorted it quick smart.

Edited July 17, 2011 by Bl4cK32

[R32Abuser]

Yeh its weird tho...

I dont think I ever had any problems with timing or the like on my RB20DET. And it was exactly the same unit used on this RB30DET. Strange...

[Bl4cK32]

neither did I. Never had troubles with timing on the 20, cas was great. Slapped in the 31 and it was all over the shit. NVM, wait n see I suppose. Wont be too long or too hard to sort.

[bubba]

It could be cam timing but it won't be because you're using 25DE cams, we've pushed 365rwkw through my standard 25DE head and a stock RB20 plenum & throttlebody.

[Cubes]

Ahhh yes its been some time since I pulled the GT30 off.

"What power was it making even though you only saw 8degree's ignition timing?"

Car made 207RWKW on the 8 degrees worth of timing. Got to drive it to the assemblers - Im in love

207rwkw - on what boost? Power is definitely down either way you look at it. Your running catch can(s)? Do you mind if I ask who's tuning it?

"Mine with the std RB25DE cams was very much knife edge - it 'really' wanted to ping easily. RB25DE cams really aren't much chop, their specs are not ideal for turbo app."

This may be one, if not the issue! But at only 8 degrees?[/i]

Mine did want to ping easier with the rb25de cams in it but it still made the expected power (250-260) if not a little better (268) on 1bar.

"Ensure the CAS is ok - shove a timing light on her as you bring rev's up to ensure its not swaying timing as rpm increase, a faulty cas will cause det issues. (Darren I remember yours had this issue)"

This will be checked subsequent to the compression test. Still though, I really doubt its the pistons and am hoping its simply just a timing issue.[/i]

Given the above and below - definitely the first port of call. Fingers crossed its a simple fix.

"You have a std exhaust manifold - The std exh manifold is T3 divided. t3 divided is larger than the single inlet of t3 gt30/gt35 inlet. Ensure you rip the exh. housing off and port match it to the t3 divided gasket. Don't think its ok to have that ridge there, it kills power."

Did you do this to the exhaust housing on your old GT3076R? I can see it would hamper the flow considerably![/i]

Sure did - I port matched the exhaust housing so there won't be problems with it, that pic is of your exhaust housing before/after.

Are you still running the std inlet manifold/plenum? I port matched the inlet manifold to the plenum as there was also 'some' runners that were out by a good 3-5mm. Substantial IMO to have some runners that are fine and others that are extremely poor.

Yes. Still running standard inlet manifold/plenum. I would have thought that the engine builder/assembler would have picked this up and mentioned it if there was an issue. Ill be doing this aswell if that is the case.[/i]

Its not really an issue - I simply tried to make everything perfect. A few mm here a few there all adds up.

Theres not alot I can do at the moment due to it being the weekend. However, hopefully more information comes about in the coming week. Joel, if you dont have a problem with it, Ill contact you via the email address I have when I bought your old turbo off you. Just want to run a few things by you regarding these issues!

No problems at all.

[r33_racer]

Thats crazy how big of a step is there on the exhaust housing. Its always good when you pick up on little things that make a big difference to power!

Free power ftw!

[R32Abuser]

Cubes,

car made that power on what I think was 15 PSI. Not 100% sure but will be finding out more today. Ill see if i can track down a dyno graph.

Got some of the specs off Spool for the pistons, HG thickness etc. Will be speaking to the assembler today.

I'll shoot you an email Joel with some more information.

Will update later today!

Cheers!

Edited July 17, 2011 by R32Abuser

[R32Abuser]

Spoke to assembler today...

Compression test still yet to be done

AFR's were apparently spot on. So besides the pinging nothing is too suggestive!!!

[R32Abuser]

Comp test was 160 odd across the board...Was promising before I had talked to Paul from Red R Racing.

Paul says that after doing a back calculation using those pistons with the head I have (obviously with some small assumptions) the static C.R. will be sitting in the 10's.

The only reason I bought those pistons was on the basis that those heads are listed to cc up 62-66cc between the three - as listed in the RB30DOHC pdf. Hence the C.R. should have been around 9.

Pretty upset that its come this far to find this information out...

That said, I still have options.

Timing is apparently being checked tomorrow, however, after talking to Paul - I doubt this will make a difference.

Edited July 19, 2011 by R32Abuser

[R31Nismoid]

Two threads about the same thing are going nowhere

Rather than merge em, and turn it into a confusing mess - ill close this one.

The other thread is in this same section, similar title etc.