Another Rb26 Compression Q&a

[Griffin]

My built 26 compression came up as 180 psi dry on all 6. Is this reading high as I've been told most stock or built ribs are around 160 psi. The gauge I used reads correctly. The test method is of no issue. Do u guys think my engine was built for higher compression as it has dash 10 turbos ?

[boostn0199]

I also comp tested a guys built rb26 and it had 180 across all 6 and again gauge doesnt seem to be out since it gives pretty expected results on other engines so it seems it is possible.

[Ben C34]

A comp test is virtually impossible to tell the comp ratio.

Too many variables.

Cam and cam timing play a huge part. The only way to know for sure is measure everything and calculate it, but I wouldn't pull an engine apart just to do that. Who built it? Don't they know?

[KiwiRS4T]

My built 26 compression came up as 180 psi dry on all 6. Is this reading high as I've been told most stock or built ribs are around 160 psi. The gauge I used reads correctly. The test method is of no issue. Do u guys think my engine was built for higher compression as it has dash 10 turbos ?

Not really an out of this world number. Don't worry about what the engine builder was thinking just concentrate on getting a good tune.

[R31Nismoid]

You don't build it for higher compression with shit turbos like that.

Anyway, too many variables in a comp test to make a definitive call. It's simply used to give an indication of health of each pot compared to the next

[GTRPSI]

Not such a stupid idea.

On something as laggy as a pair of dash 10's on a 26, your only bottom end response may come from your higher than normal compression build (if thats what your builder did), add E85 to the mix and it might be a bit of a sleeper in disguise.

Obviously there are far far better turbo choises on a 26, -10's are so yesteryear.......

Edited January 5, 2014 by GTRPSI

[Griffin]

That's what I'm thinking. I've got the engine out now to fix a bearing issue and do some more upgrades while I'm at it.

[Ben C34]

So measure it up and post results. Would be good to put the actual comp ratio (and type of cams) against a comp test result for comparison purposes.

[R31Nismoid]

Not such a stupid idea.

On something as laggy as a pair of dash 10's on a 26, your only bottom end response may come from your higher than normal compression build (if thats what your builder did), add E85 to the mix and it might be a bit of a sleeper in disguise.

Obviously there are far far better turbo choises on a 26, -10's are so yesteryear.......

But then you can never run anything but E85 given you need to run so much boost to make -10s make the power to justify, all you'll end up doing it fighting detonation as peak torque on PULP. It's not like you are going to pick-up 500rpm+ response which is what you'd need to come close to -5s... One would sooner entertain the dirty idea of living with the horrid lag, surging and everything else and just have top end (but again, bin the -10s).

[GTRPSI]

As i said, not the perfect turbo choice, but he can work around to some degree with what he has to work with, lots of big laggy turbo High comp E85 setups working quite well out there.

I wouldnt even consider it on Pulp, suicide.

Id agree with the bin the -10's for something better, surging can be to some degree sorted with a exhaust mainfold balance pipe and a deflector/seperator plate on the outlet twin turbo pipe and some tuning, but by the time you add it all up its sometimes just logical to go the smaller turbo route or a single setup, just ease for end result.

If he wants to run it he can make it work, its just a question of the whole package being right, there is quite a bit to making those ancient -10's work, its just a question if the amount of input is worth the end output.

Do you remeber Stefans car ZILLR (im his dad posting), we pissed off those -10 turbos quick smart.

They ended up on a R33, the new owner loves them, around 370KW at all 4 now (i think), tune and cam gears pulled out a lot of the lag, lost its old top end, gained a lot down the bottom, ended up being a lot more street freindly.

This was its first tune session in RWD before the 370 it pulls now on all 4 with a stock bottom end, add E85 and cams for more (and a forged bottom end would be a good idea)....

Edited January 6, 2014 by GTRPSI

[R31Nismoid]

You can't put big/laggy and well in the same sentence if you are talking sub 400rwkw!

The new owner just doesn't know any better is all that means if they are 'loved'

Put -5s on any package with -10s and it'll be night and day levels of better in every area.

[GTRPSI]

New turbo owner has been in his cousins race pace tuned R34 Vspec with -7's and a few -5 GTR's, however what he wanted with the R33 was just straight line drag type performance, without spending (key point), we had the turbos and manifolds for sale at a good price at the time.

We know him quite well, i spent a whole evening trying to talk him out for buying them due to the lag and his stock bottom end, didnt work.

Speaking of -5 turbos, Stefan told me you took him for a bit of a spin in your race pace built R33, next morning when he got up he was singing praises when telling me about it, very impressed with the setup and the way it laid the power down.

[R31Nismoid]

It had modified -9s back then

[GOJ1RA]

How about a stock RB26 with stock turbos? My test came back with around 180 across all cylinders today.

[portaz]

Cold or hot. ?

[GD51LA]

my standard 26 had 175psi (all 6), paddle was flat..

[drgtr7]

Lol my car can't be -10 one of my tunes had full boost by 4600ish. They are rather a 2530 more so.

[drgtr7]

Also they where laggy on stefans car because the actuators where f**ked.