Rb26 Lag - Compression?

[byebye]

My rb26 is extremely laggy, makes about 12 psi at around 5500rpm from memory, checked everything twice, thing is the compression is down, ranging from 135-118, would this be the cause of that amount of lag? only other thing that im unsure about is that its got split dump pipes on it and have never had anything to do with them

cheers

[byebye]

forgot to mention - stock turbos and its been tuned (power fc)

[quick31]

Compression is a contributing factor but it should be boosting up earlier than that. I would check for vac/boost leaks.

[GTRsean]

Check for restrictions in intake, or exhaust, eg stuffed cat.

[byebye]

the whole car is apart for the second time, everything changed with something that had known to be working off a mates, i just havnt had the head off.

[DVS JEZ]

What cat is it running? Check its not fully/partially blocked.

Have u got adj. cam gears?

Are they N1 turbo's?

[6boost.com]

Check base timing too...if you havn't already!

[byebye]

checked base timing 3 times mate haha, no they are stock turbos not n1s, im from tasmania i dont have a cat lol, yes it does have adj cam gears, could it be possible its a combination of incorrectly set gears and the low compression?

[r33_racer]

Havent changed a timing belt recently?

[GTScotT]

If its still got enough parts to run a stock ecu, put the stock ecu back in and see what that does.

The motors performance is only as good as the tune.

[DVS JEZ]

Cam gear settings will affect compression.

Set them to 0 and do another compression test.

[byebye]

still laggy with stock ecu, timing belt has been changed before i got it but the car has always been laggy but timings been tripple checked?

from memory the cam gears are pretty close to 0

[smithy85]

stock wastgate(s) not sealing correctly?

[byebye]

Its got adjustable ones on it for some reason,had heaps of tension on them too

[smithy85]

Its got adjustable ones on it for some reason,had heaps of tension on them too

readjust the rod length of the actuators, may take a bit to get them right but it sounds like it should fix your problem.

[byebye]

they are so tight i struggle to get them on? heaps on tension on them!

[Duncan]

yeah that is normal. there is generally about 5mm preload that you have to push back againt

[GTRNUR]

Most lag issues ive seen are because of air leaking from the induction side of the engine somewhere between the turbo's and the throttle bodies. I recommend blocking the hose from the twin turbo pipe to the intercooler with a plug and then pumping up the intake manifold with an air compressor and checking for leaks. You will spot most leaks with just a few PSI of pressure but you should pressure test to about 10psi above your target boost pressure.

If you find any leaks you should re-set your actuators to stock positioning, or you will end up overboosting on your first test drive and break off turbine wheels.

[byebye]

ill check to see if its around 5mm duncan, yeah i blocked it up found a leak, fixed it and it made bugger all difference, also found an exhaust leak on number 3 cylinder from head to manifold where some champion had half broke the stud but i havnt had the car back together since finding that but i cant see how that would make that much of a difference really

[byebye]

and with these adjustable actuators id rather piss them off will i have any problems if i put n1 actuators on there?