Rb25/30Det

[DVS JEZ]

I was speaking to Paul from Red R Racing he measured (cc)the rb 25 det head from my customers build while i was on the phone to him and he knows RB26 heads like the back of his hand.

OP exactly which pistons did u get from spool?

[R32Abuser]

6cc dome ones. Spoke to Paul and will be speaking again tonight.

Not looking good

[Bl4cK32]

whose tuning it? A simple compression test shouldnt have taken this long

[DVS JEZ]

agreed but it seems that the engine combo is at fault

[Bl4cK32]

agreed but it seems that the engine combo is at fault

hasnt ruled out timing or compression, which should have been done straight away. Id worry about the pistons last if he used off the shelf ones the same as cubes and I had.

[DVS JEZ]

totally agree, very curious to know what comp its built too. compression test may not give the results we are after, lots of variables

[R32Abuser]

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

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.

[wolverine]

E85 will love the static comp.

[Bl4cK32]

right pistons, right head, then wait for the timing and comp tests.

[Cubes]

Rob82

Im unsure how they tested the CAS as I was not there. However, I suggested the CAS could have been a problem but they replied by saying that if that were the case they would have been getting funky readings/timing all over the rev range (which they weren't apparently).

Problem is, If we do lock in 20 deg timing and take it to 6000RPM it will PING/KNOCK its head off and possibly cause damage. Something which I dont want to do. I will be suggesting the CAS sensor/assembly having an issue again.

Thanks, the setup is pretty much identical to Cubes RB30 setup. In fact, it is his turbo which is bolted on the side of my motor I got to drive it between the tuners and the builder/assemblers. Made 207RWKW with 7-8 degrees worth of timing but still feels SOOOO responsive!

As a result of the answer in bold - Time to get a second opinion if he was referring to the timing read out from the ecu when tuning. :S

The timing the tuner see's via his tuning software will not show the CAS swaying timing about. The only way to check it is as Rob82 suggested, in idle, timing light and bring rev's up. No load so it won't ping.

Comp ratio - 160psi isn't excessive. Don't go ripping pistons out just yet. I'm almost willing to put $$ on they are not the problem.

R32 RB25DE heads always cc up around the low to mid 60cc's. RB25 Neo heads are the only ones I remember ccing up in the 50's.

My money would be on the CAS or you have some sensitive knock sensors and the tuner is going off them. Its a worry if he is.

RB26 ones went in with a 26pfc and all was good.

On a second note - you are running a catch can setup?

[R32Abuser]

No catch can setup.

Tuner said it was an audible knock. I.e. didnt need a sensor to hear it! Knock sensor reflected this aswell.

Im soooooo confused right about now!

[Cubes]

No catch can setup.

Tuner said it was an audible knock. I.e. didnt need a sensor to hear it! Knock sensor reflected this aswell.

Im soooooo confused right about now!

Is it breathing?

And get a leak down test done.

Pull the recirc off and see how she's breathing.

I used to run two catch cans to keep it stockish looking. One either side using the std plumbing - the PCV was blocked off but connected to make it look legit.

[Duncan]

Comp test was 160 odd across the board...

That is a perfectly normal compression, or a tiny bit high if it has had no run in.

You need to look at simple things liek base timing and cam timing before pulling the motor out.

[DVS JEZ]

Compression test can be mis leading if th cam gears etc have been adjusted.

[R32Abuser]

Motor has been "run" in on the Dyno for about 30mins to bed the rings and bores in. Still on thick castor oil until 1000km.

Cams are all standard as well as cam gears. So no real adjustment there.

Spoke to a couple of blokes last nite who have built pretty much the same setup as me except pistons. Can anyone confirm the head cc of an R32 RB25DE?

[Bl4cK32]

I can show you the pic cubes took of our heads with the cc written on it in texta after it was done if you don't believe it was 62.2cc

[ido09s]

I would go somewhere else and get a second opinion.I dont know how the motor was built but to be tuning it for full load on a 30 minute old engine seems a little odd to me. Please correct me if its only a base tune for the run in process that they are doing.

Are they sure that its knock they are hearing and not an engine noise?

Edited July 19, 2011 by ido09s

[R32Abuser]

I believe you Darren just seeing if others have found different heads etc.

I wasn't there so I can't speak for the tuner, but it was audible enough for the tuner to stop the tune!

[R32Abuser]

As for the tune- I believe it was a "power" tune. After that, drive for 1000km, not too harsher driving, then drop old castor oil and put synthetic in. I may stand to be corrected tho so don't take it all as gospel.

Edited July 20, 2011 by R32Abuser

[Rolls]

If the head is the right size, then what would cause massive pinging like this?