Just did a compression test on my rb26 - need help please (sad news)

[Eddie99]

Hi everyone hope all is well I have a new question if anyone can shed some light to me I took my r32 gts4 rb26 to the mechanics and they ran a compression test on it The results don’t look good

CYL 1 160

Cyl 2 160

Cyl 3 162

Cyl 4 100

Cyl 5 145

Cyl 6 150

This was a cold compression test because the car isn’t able to run at the moment  (no turbos on it) The shop that done the tests also quoted me 1.5k to strip down and tell me what they find. I told them wouldn’t it be more reliable to do a leak down test? After speaking a close friend he said he doesn’t understand why Cyl 4 would be so different to the others.

I also spoke to another jdm expert shop that builds rbs and they said theirs no point putting OEM parts again because they are 25-30 years old and that I’m better off forging the engine. They said 12-14k solid forged long motor + removal , re fit, fluids , gaskets, parts , tuning will be extra.

wanting to do a leak down test before i pay the mechanic to do a strip down, is that worth it? or better off doing the leak test to find the issue?

 

cheers 

[Ben C34]

Regardless of the issue the engine has to come apart. Head off minimum then see if it something in the head. 

 

Or ignore the results and get it running and see what happens. If it has sat Un-running for a while it may come good, but that is wishful thinking.

 

If it is pretty easy to get running just do that. Why was it comp checked? Most of the time you are better off not knowing!

 

[Ben C34]

Car can definitely  run with no turbos ( with some creative afm plumbing);. Start it up and give it a bit. Then retest.

[Duncan]

Sorry but those results are a good example of bad news, it won't be just a test issue or similar (unless you can't repeat the result on #4). At a minimum head comes off but more likely it is a broken ring land because valve issues most often give 0 compression

[Eddie99]

It started having boost problems In the top end of the boost range, so I decided to check all the hoses and the turbos themselves to see if they had shaft play which they didn't but with my boost controller I could have half boost feed the engine and it seemed to hold that fine, also changed a few clamps over regarding to the hoses cause they were a bit crap and replaced a flange section which had a crack in it, after fixing all that it still didn't run properly and couldn't figure it out so make life easier I decided to change it for a single but then once the singles were out mate told Me to do a comp test Write to

 

@Ben C34

[Eddie99]

yeah i was thinking that ( say its the head ) i spent 8k on doing the head but then the bottom end goes and i gotta do that

@Duncan

[Murray_Calavera]

If you have room at home/garage, my vote would be to buy a long motor known to be in good condition. Put some upgraded studs and head gasket in it and drop that motor in to get you up and running again quickly.

Then with the stuffed motor, pull it down and slowly rebuild it at home yourself. Plenty of resources available these days so that any motivated person would be able to learn to build a motor. 

Will work out cheaper then paying someone to build you a forged motor, you'll end up with a good condition spare motor and you'll develop the skills you'll need to keep the skyline running long term. 

[r32-25t]

Bolt turbos on it and send it, I’ve seen plenty of them run for years with results worse then that, including my own. Then build an engine on the side and do a swap when you get around to it