Jump to content
SAU Community

Recommended Posts

Sorry for the lengthy post and I hope it all makes sense.

Back in 2011/12 my R33 S2 GTST was setup with the following:

GT3076 .82 internally gated
Usual supporting mods.

PLUS:
740cc injectors
460lph walbro FP
Camtech 256 cams with adjustable camgears on inlet and exhaust
PowerFC
Tuned on e85 made 344rwkw @ 21PSI.

Around 2014/15 Motor eventually let go as expected as I was pretty hard on it.
The crankshaft bearing was gone, got someone to help me replace the bearing but the wrong sized one was put in, it grabbed and shot a piston out of the side of the block.

At this stage the only option was to replace the entire motor, and it was changed with a stock S1 motor.
The cams were not changed into this motor and I can't remember exactly why (Either they were damaged or we ran out of time at the workshop and my car had to go)
This motor was running the previous motors tune (tuned with the old cam setup etc)

Shortly after and before I got a chance to get it re-tuned, I got defected (for like the 10th time) so I gave up and the car sat at home untouched for 5 years.

Fast forward to 2020 I just put the standard turbo back in it and managed to get it running and it is now re-registered.
it is still running that original tune.
I obviously want to put the 3076 back on and install (at the very least) an adjustable exhaust camgear and get it re-tuned but I thought I best do a compression test on it before I start.

Results were pretty bad (could only do it while cold because FP is currently out of car pending replacement so couldn't warm car up first): 

CYL 1: 130
CYL 2: 90
CYL 3: 130
CYL 4: 80
CYL 5: 90
CYL 6: 95

My question is have I done damage to the engine by driving it around on the original motors tune (which had the 256 cams) on the new motor (which has the standard RB25 cams/cam gears)?

Thanks

Edited by brentos
Link to comment
https://www.sau.com.au/forums/topic/480198-concerning-compression-test-result/
Share on other sites

depends on how you drove it.....
Tune maybe rich in some places & lean in others. Ignition timing would definitely not be optimal.
How did it drive? Was it blowing smoke?  
Was the engine comp tested before being installed?
I'd be doing a leak down test too. Get it running and redo comp test. Check oil & coolant to see if that is mixing or getting combustion gas in cooling system.

My internet diagnosis is going to be blown head gasket between cylinders.

There's a whole lot of other things that could be wrong. Examples;

The S1 engine could have been well worn when you bought it.

The rings in it could all be stuck in the grooves, needing to be run properly to free up (or possibly dismantled and cleaned/freed up.)

 

 

29 minutes ago, robbo_rb180 said:

depends on how you drove it.....
Tune maybe rich in some places & lean in others. Ignition timing would definitely not be optimal.
How did it drive? Was it blowing smoke?  
Was the engine comp tested before being installed?
I'd be doing a leak down test too. Get it running and redo comp test. Check oil & coolant to see if that is mixing or getting combustion gas in cooling system.

My internet diagnosis is going to be blown head gasket between cylinders.

 

22 minutes ago, GTSBoy said:

There's a whole lot of other things that could be wrong. Examples;

The S1 engine could have been well worn when you bought it.

The rings in it could all be stuck in the grooves, needing to be run properly to free up (or possibly dismantled and cleaned/freed up.)

 

Thanks for the replies.

Drove it hard at times, but not always. 

It drove well.

Was not blowing smoke back in 2015. Recently after getting it all back on the road again my missus was driving behind me and said she saw a burst of white smoke within the first 20 seconds of driving after having just started it, but it apparently went away and was fine the rest of the way home.

Can't recall whether it was comp tested when I first got it, my memory is pretty bad but I have a suspicion that It wasn't.

Coolant flush was done last week, it was in pretty poor condition, rusty old water, but no traces of oil. Now it is nice and green and still doesn't appear to be have any oil in it nor is there foam coming to the top. I am yet to dump the oil to check it but will also do that this week to check how it looks.

Fuel pump hopefully going in sometime between weds and fri depending on when it gets delivered. Will run it and warm it up to do a hot test.

Will also look into doing a leak down test, I will read up a bit of info on how to perform one first.

I should point out the other day, started the car it was running on 5 cylinders, diagnosed it as CYL3 by doing the unplugging of the coilpack one-by-one. I swapped coil 1 with 3 (labelled them all first so I don't mix them) and the problem stopped and I haven't been able to replicate it since. But to be on the safe side I have since ordered a new fuel pump (Because the old one was sitting there for 5 years while car wasn't running), replaced all plugs (went one range cooler to BCPR7ES because there was indicators of lean conditions on the old plugs), replaced fuel filter and have also used engineering sealant on the Splitfires to seal in any hairline cracks or what not. May also change the coilpack leads.

Edited by brentos
34 minutes ago, GTSBoy said:

There's a whole lot of other things that could be wrong. Examples;

The S1 engine could have been well worn when you bought it.

The rings in it could all be stuck in the grooves, needing to be run properly to free up (or possibly dismantled and cleaned/freed up.)

 

Good point. Was the car on e85 only when stored? could lead to moisture build up in the cylinder which leads to corrosion.

1 hour ago, robbo_rb180 said:

Good point. Was the car on e85 only when stored? could lead to moisture build up in the cylinder which leads to corrosion.

Yeah it was on e85 only when stored. Although the tank and lines were emptied before it sat there for 5 years

1 hour ago, r32-25t said:

Shove more boost in and do send it 

That thought did cross my mind haha

1 hour ago, robbo_rb180 said:

30 seconds into test drive
atomic bomb explosion GIF

?

Edited by brentos

could be stuck rings like gts boy said. Get a can of that seafoam stuff or Subaru upper engine cleaner. Take plugs out and chuck around 20 ml in each cylinder and let it sit overnight. Then follow directions on the can. Ive heard of guys running it through the fuel tank and oil for a bit before a flush. Worth a crack i reckon. Otherwise just send it as already advised.

On 21/04/2020 at 9:25 PM, admS15 said:

could be stuck rings like gts boy said. Get a can of that seafoam stuff or Subaru upper engine cleaner. Take plugs out and chuck around 20 ml in each cylinder and let it sit overnight. Then follow directions on the can. Ive heard of guys running it through the fuel tank and oil for a bit before a flush. Worth a crack i reckon. Otherwise just send it as already advised.

The new fuel pump finally arrived today and I just finished putting it in tonight. 

I thought it might have been worth while doing a warm test after running it for 10 minutes before ordering and trying Seafoam or Subaru upper engine cleaner.

I got much more consistant results:

CYL1: 90

CYL2: 85

CLY3: 90

CYL4: 90

CYL5: 100

CYL6: 100

Actually I probably only idled the car for 5 mins last night before checking so it was more like a lukewarm test.

Would it be worthwhile going for a drive now for 30 mins and testing it again, properly hot?

The thing about this is … hows it drive?

If it's anything other than "great!" all this does is point a finger at whatever is not great.
To fix anything all is the same 'fix', i.e tearing engine apart and rebuilding.

If engine is great, drive until engine not great.

Damage to engine doesn't really result in overall low compression like that. Damage to engine realistically is detonation, which results in holes pistons and the car generally running great until said holes exist, in which engine suddenly drive not great.

I guess you could have had excessive fuel washing down the bores for a huge amount of time causing uniform rings not sealing or something, in which case engine not great.

Drive car, rebuild if engine not great. Maybe take it easy and save $ until you can confirm engine actually still great.

It'll break shortly after you decide this anyway.
This is the Skyline Experience.

Thanks for the replies

 

On 25/04/2020 at 3:25 PM, GTSBoy said:

They're not going to magically come up to normal if they are at that level "lukewarm". The engine is either toast, or one of the less severe but still possibly have to pull it down versions of "not quite right".

Agreed, it is what it is.

Just another quick question: The cam timings being off affecting the valve opening/closings wouldn't make it slightly lower than what it should be (considering how they are all now at least consistent?)

 

On 25/04/2020 at 4:07 PM, r32-25t said:

Or the compression tester is shit and reads low (seen it plenty of times)

It is a $50 Autobarn tester, I am not sure how good it is considering the price is on the cheaper side compared to other ones.

I know my Dad has a proper good one, I should have just waited and used that to know for sure.

On 26/04/2020 at 12:49 AM, Kinkstaah said:

The thing about this is … hows it drive?

If it's anything other than "great!" all this does is point a finger at whatever is not great.
To fix anything all is the same 'fix', i.e tearing engine apart and rebuilding.

If engine is great, drive until engine not great.

Damage to engine doesn't really result in overall low compression like that. Damage to engine realistically is detonation, which results in holes pistons and the car generally running great until said holes exist, in which engine suddenly drive not great.

I guess you could have had excessive fuel washing down the bores for a huge amount of time causing uniform rings not sealing or something, in which case engine not great.

Drive car, rebuild if engine not great. Maybe take it easy and save $ until you can confirm engine actually still great.

It'll break shortly after you decide this anyway.
This is the Skyline Experience.

Well I took it for another drive on the weekend after putting it all back together. The new fuel pump, new plugs, new fuel filter went in and the splitfires were put back in after being sealed with Selleys 601 - it drove great.

Just got the 3076 rebuilt , may just pop it back on and take it back to the tuners to get them to fix the tune/timings and see how it holds up on the dyno and if all good I will drive it until it breaks then look into a rebuild etc.

  • Like 1
42 minutes ago, brentos said:

Just another quick question: The cam timings being off affecting the valve opening/closings wouldn't make it slightly lower than what it should be (considering how they are all now at least consistent?)

A little bit, but not 50 psi worth.

42 minutes ago, brentos said:

It is a $50 Autobarn tester, I am not sure how good it is considering the price is on the cheaper side compared to other ones.

Direct comparison of the one you have against ANY other compression tester is a good start. It is more likely that two testers that agree are both good than both bad to the same degree. Although it is always best to compare against a trusted unit that is known to read correctly. Once you've done that, the newly tested unit also becomes "trusted" for a while.

I've always looked for consistency rather than a PSI figure with compression testers - at around 10psi difference in your last test I'd say it's OK

Does it use any oil?

On 27/04/2020 at 9:24 AM, GTSBoy said:

A little bit, but not 50 psi worth.

Direct comparison of the one you have against ANY other compression tester is a good start. It is more likely that two testers that agree are both good than both bad to the same degree. Although it is always best to compare against a trusted unit that is known to read correctly. Once you've done that, the newly tested unit also becomes "trusted" for a while.

I used a better quality gauge that my Dad had and here are the results:

CYL1: 145
CYL2: 115
CYL3: 120
CYL4: 125
CYL5: 130
CYL6: 142.5

19 hours ago, Chris32 said:

I've always looked for consistency rather than a PSI figure with compression testers - at around 10psi difference in your last test I'd say it's OK

Does it use any oil?

Na it doesn't seem to be using any oil, the oil went in 2 months ago and I just checked it still at the max. It is a little thinner than when it first went in but I assume that's just a reaction to the E85

11 hours ago, Ben C34 said:

Less testing, more thrashing.

I like your thinking haha. That's the plan now

Edited by brentos

Some notes on the results.

Either your technique sucks or there's significant difference in the other parameters of the test (hot vs. lukewarm, etc). This because your cheap gauge read very similar for Cyl1 & 2 but your dad's gauge was very different. With other such differences across the 6 reads also.

Assuming we trust your dad's gauge, there is enough variation between the highest and lowest to still be concerning as to the condition of those lower cylinders.

And, it is still possible that stuck rings are getting better, at different rates, etc etc.

  • Like 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...