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  • 2 weeks later...

thanks for the replies guys, havnt messured the pressure across the core yet, I want to try and suss it out a bit before I go out and spend 1k+ on a new manifold, the guy who's tuning it think the manifold and split/non split issue shouldnt affect top end power but would just make it come on later. is it normal for a t04z to make 20psi before 3700rpm in 4th? it will start making boost (1-2psi) at about 1900rpm in 4th, mayby the turbo im using doesnt have run of the mill blades in it so it would come on earlier but make less in the top end,

the cam gears are set to 5 deg advance on the intake and 1 deg retard on the exaust, ive read of some people having the cam gear set up completely different but have been assured by the tuner they are in the best possible position.

  • 1 month later...

the guy who's tuning it think the manifold and split/non split issue shouldnt affect top end power but would just make it come on later.

LOL WTF!!?!?!?!

you have said it doesnt line up with the ports by 3mm...you now have 3mm smaller exhaust ports + the gasses are hitting a 3mm wall of restriction...turbulence much?!?!?

Throw the manifold at who ever sold it to youi really hard!

  • 4 weeks later...

well your engine is EXACTLY THE SAME as my rb26. turbo, injectors exhaust intercooler.apart from mine having a old autronic smc.

mine makes 376kw on 26psi. stock valve springs. it falls over up top from float isssues.

as for a comparison i went from 315 to 376 with the head work and poncams. so the head is where the issue is. i would play with the cam timing. mines +3intake -4 exhaust.

start at 0 setting and have a fiddle.

these guys spent quite a bit of time mucking around with the cam timing aparently, couple more weeks ill have the coin to get a 6boost mani, then ill take it to the guys a uni group see if they can nut it out. will post up once I have some results though, i think it is in the head but it is the mani that is causing back pressure so it cant flow enough gass out, as its making 4kw more on 20psi from 16 psi

just checked what my cam timing is at, in 5deg adv ex 2 deg retard

mayby i should take this info to uni grp and ask them to play with the cam timing and do a general check of the tune before i get a new manifold?

  • 4 weeks later...

I have a similar issue 420ish hp is it. I think mine is all in the cam timing

Trying to hard to get it onto boost. My -5's 18psi @ 3500rpm. Mine just won't take any timing.

I have a real big lumpy idle which sOunds tough but is robbing power

<br />thanks for the replies guys, havnt messured the pressure across the core yet, I want to try and suss it out a bit before I go out and spend 1k+ on a new manifold, the guy who's tuning it think the manifold and split/non split issue shouldnt affect top end power but would just make it come on later. is it normal for a t04z to make 20psi before 3700rpm in 4th? it will start making boost (1-2psi) at about 1900rpm in 4th, mayby the turbo im using doesnt have run of the mill blades in it so it would come on earlier but make less in the top end, <br /><br />the cam gears are set to 5 deg advance on the intake and 1 deg retard on the exaust, ive read of some people having the cam gear set up completely different but have been assured by the tuner they are in the best possible position.<br />
<br /><br /><br />

that sounds about right, is a few hundred RPM in front of my RB28, but mine goes on to make 710awhp ( hub dyno ) Garrett TO4Z .86 rear, no name exhaust manifold, lots of head porting and 272's

  • 2 weeks later...

havnt fixed it yet, went away for a month so it didnt get worked on and yup i bought one of those in a 0.96ar two weeks ago, took it all apart last week, when the mani got the flange angle changed it must have gotten too much heat into it and caused it to warp, so sending it off tomorrow to get machined flat again, matched the ports to the head so yeh fingers crossed, after that it'll all be going back together and then have the dump redone (new type of v-band flange on the new housing) if it needs it then off to uni group for a tune.

will keep this updated when i get some news on it

cheers

  • 2 weeks later...
  • 2 weeks later...

Had great fun, had to get the turbo flange machined straight as when the guys changed the angle, too much heat and one corner sagged + the weld on runner #6 was cracked and had to be re welded, real quality bit of gear.

But now that its sorted with a new housing and no leaks it feels better, just feels stronger i guess, but ill have to wait a few weeks till i can arange to get it on a dyno for another tune and to see if its not just my head playing tricks on me wanting it to feel better.

Fingers crossed

  • 2 weeks later...
  • 1 month later...

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