My Comression Test

[B-Man]

For Steve and those wondering:

I was told that 2 of my cylinders lost compression.

So got a compression tester today and checked for myself....

I don't know which cylinder is which, but for the sake of it , My Cylinder 1 is the one closest to the Crank Angle Sensor and cylinder 6 is the one closest to the firewall.

Cylinder 1 - 127 PSI

Cylinder 2 - 55 PSI

Cylinder 3 - 150 PSI

Cylinder 4 - 40 PSI

Cylinder 5 - 50 PSI

Clyinder 6 - 50 PSI

Hmmmmmmm - I don't know how the car even started.

Since 1 & 3 are OK-ish - that sort of rules out the plenum doesn't it ???

[meggala]

I wouldnt rule out anything that is ring wear so you will be lookign for rb 26 pistons then they aret that dear

130 each or so

not good

[B-Man]

Megs for the extra $600 I think I will go forged - Aries or Arias - whatever they are.

[meggala]

k

its your choice and your money

[Ryno]

B-man, was it a big job - doing the compression test?

[B-Man]

about 30 mins for me - but I don't have the standard plenum & intercooler piping so it's heaps easy for me to get at the plugs.

[EnricoPalazzo]

Same as changin spark plugs i would say

[B-Man]

Originally posted by meggala

k  

its your choice and your money

he he - Yeah, more money that sense ....... not

[Steve]

Jeez, you did a good job there Brendan.

As what megs says, dont think you can rule anything out as yet - plenum, injectors, or ECU. But I would definately get the injectors tested esp as they have been highflowed, find out what the difference of flow rate is and what pattern they are spraying. As the head has to come off, removing the injectors would be pretty simple/cheap and the testing isnt too expensive - I had my new ones flowed for $5.50 each.

Then get the plenum tested too, to be on the safe side. Must be someone in Sydney with a flow bench who could give you a figure.

With ECUs quite often it has something to do with who is punching the figures. Which one are you using again?

At the end of the day, the engine could have had a hard life in the hands of the previous owner - but I would like to make sure before I go puting stuff back on, just to be on the safe side.

Still laughing at the compression test results - sorry but its pretty funny:D

[T0nyGTSt]

That result blows me away...

Mine was 1 -> 5 = 160

6 = 60 dry, 68 wet...

T.

[B-Man]

I'm gonna do the test again on the weekend - Thinking more about it - it can't be right. Cause the engine starts (doesn't idle tho) - and I drove it for a short distance after failure. Surely, with a result like this , the engine wouldn't run.

When I was doing the compression test - the battery was dying, I dunno if that would make a difference ?? I've charged it up now, so I'll do the test again to be sure to be sure.

Steve - you are right - it's pretty funny. But you know what ...- I spent the money on these mods, missed 3 track days waiting for the bloody thing to finish, it still wasn't right so I took it back - Told them I had to have it back for a Skidpan day - So the day before the skidpan day, they tuned & dyno'd - Then driving to the skidpan day - this happens - 2nd gear - 3/4 throttle - under the speed limit, accelerating fast but not flat out - then poof. And I did not touch the boost or anything to do with the setup.

So, yes, while I can laugh about it now - I wasn't laughing when it happened and for about 4-5 weeks after that.

Now I realise that when modifying cars this can happen and you must choose and research the parts , etc, etc, you go with very carefully.

It's also why I am going a bit over kill on the new rebuild Specs - Megs mentioned GTR pistons, which are good - but forgies are better so that's why I'm doing that -

PS - I was running EMS - but not any more - I'm chucking that shit out - And am going to go Autronic or Microtech. (I did consider MOTEC bu that was a little too over the top I feel)

I'll be getting the injectors re-flow & pattern tested for sure. No doubt about that - Also the fuel lines , pump, rail and regulator - they were all meant to be new & good.

Once burned - Twice Shy !

[meggala]

Hi B-man it sucks I think if your injectors were hiflowed you might find the issue there. any way

the motor can and will run mine ran fro 8 weeks with 0 in one cylinder and 4 in another the rb's ar a well built motor.

I ahve heard a number of disturbing stories about the hiflowed injectors and wouldnt use them. thereis a reason why the after market injectors are expensive.

honestly If your pulling the ems I would only use a power fc seriously and I would consider going to a stock plenium or a greddy unit.

the gtr pistons are great but I understand why you want to go forged.

do your build run the stock injectors tune it for 200-220 rwkw for now then come back and go for the stronger tuned once the car is run in etc.

its not until you have a major failure that you start to see the benifits of a plan hence the part on my site re mods its important.

dont loose heart you will get there but there is nothing worse than having your baby in the shop . atm I have 2 babies in the shop the cefiro just about finished with compliance and my next project the r32 with the sr 20.

its and interesting fun game modifying cars the problem is once you start you get to be an old boy liek me and you just keep on going

meggala

[red900ss]

Hey Brendan, I heard about a guy in Brookvale the other day who is researching/building plenums etc for the RBs. Does alot of work on flow rates etc.

I'll find out more....

[B-Man]

Cheers for that Dino - that would be very interesting news - and local too - Bonus. Very keen to keep hear about that !

Steve, I think you might be right about the Power FC - It's proven and it has the runs on the board and to me, that is important - I've been thinking about the ECU quite a bit - and talking to different shops about it - I reckon they only want to sell you what makes them the most margin - Not what the best solution is. The PFC is un-surpassed. Means a bit more re-modification for me tho - as I got no AFMs - he he Good excuse for some Z45 or Q45 or whatever those wideband ones are called.......

Greddy plenum prolly the way to go - just cause of the way my FMIC piping goes. Plus I agree with keeping all the piping shorter. That's unless Dino discovers a Goldmine. Hears hoping.

You know - apart from the lost $$$ and disapointment of all this - I am still having fun - and that is what counts at the end of the day !

[Cubes]

It definately sounds like a poor tune issue unfortunately.

Then there's JMS pulling 300rwkw out of a RB25 no problems....

[adam 32]

yeh thats one rooted motor....

did you check the plugs for signs of detonation?

[Lepperfish]

Who tuned the car last B-man ? Wasnt it Hills ?

[B-Man]

Originally posted by adam 32

yeh thats one rooted motor....

did you check the plugs for signs of detonation?

Adam, I did look at the plugs - but I don't really know what I was looking for - I was expecting to see near brand new plugs cause we replaced them less then 2000kms before the failure.

What I saw was a small rounded end to the centre core - lots of carbon, & very dry - this was on every plug.

The plugs could have been changed on me tho - without me knowing - as they were loose - also this may be because the shop had tested the compression.

Not really sure to be honest.

I really want to find the root cause to my engine failure - only to fix whatever it was that happened.

Thanks all !

[Guest mort]

B-MAN we had an RB26DETT with exactly the same symptoms as you describe and it ended up being a bore wash problem, someone had tuned the engine extremely rich and washed all the oil of the cylinder walls causing 5 out of 6 pistons to grab the cyl walls be very careful of who is tuning your engine and remember dyno figures don't mean a quick car.

[B-Man]

So - too rich can cause problems too ??? OMFG. You learn something new every day.

Thanks Mort - I'll take that advice on board.