1uz power dropping off after coming on boost

[millsi]

Ok guys, I posted this up over at fat pf and have got a few ideas on what to try.
seeing as though a few of you here have fi 1uz I thought I might see if you have any other ideas.

Pretty much the power drops off once the revs get above 4000ish.

Spark is fine according to the dyno op, has a cdi and coil packs.

Ecu is EMS 4244 v4

has WI (snow performance stage 2 kit) which comes on around 5 psi and is on full by at 8-10 psi.

is running on e85, turbo is a gt42 with 1.06 rear.

engine is internally standard

tuned said it wasn't wheels spin/ trans slip (though i will try a run with the converter fully locked)

trans is an mv built a340/341 combo with 3000 stall. supposed to be goo for 450rwkw+

little bit more info here http://www.lextreme.com/forums/showthread.php?t=6548&page=2

here is the dyno sheet
sorry i don't have the afr's. the tuner said he couldn't see anything in the logs that would suggest the problem.


Justen has suggested that it should be around 380rwkw once running correctly

 

[JustenGT8]

and then some mate It does look more and m,ore like valve springs other than something weird is also happening at the lower boost. If it didn't start jumping around i'd say you have a flow choke.

If it's not spark, and apparently the tuner is the world's best and says it's not Then is really only leaves valve springs. The fact it gets worse with rpm does seem to support this might be the problem.

Any idea of the history of the motor as springs shouldn't be that cactus? Stock cams right?

 

[millsi]

Stock cams, motor hadn't have timing belt done when i got it.
That of course doesn't mean that it had under 100000kms on it.

 

[JustenGT8]

kays won't matter, these things will run forever with no issues if treated right....more the life it's led. Just putting aside valve springs for the moment.

The 10psi plot does roll over a bit earlier than i would expect given other auto dyno runs from a UZ that are around? Looks like a pretty normal plot from an auto otherwise.

If it's a flow issue and you are hitting some type of choke it's hard to see what it would be on your setup as everything looks well made and plenty large enough? Any part of the system you might have some concerns about that we can't see?

 

[millsi]

if anything id say the exhaust manifolds are too big. i think being narrower would aid gas speed.

the intercooler may be the problem if its going to be anything restricting it 600x300x75, has 3"in and out though. rest of intake is 3" with 90mm throttle body.

i pulled the cooler out after the first dyno to check it wasn't blocked.

think i might just bite the bullet and start saving for a proper built motor. is the 2uz the same size and are the mounting points identical to the 1uz?

 

[XR8tt]

I run near 500 rwkw on 5.4 push-rod with a Hybrid intercooler that size..
Yep I would say valve springs..For sure !!!
Keep in mind they are lucky to have 50Lb seat pressure std...

The size of dump pipes and spark blow out can be issues..
Is the fuel pressure holding ?? Any dips means fuel pump isn't keeping up...
"Baffled" mufflers restrict turbo motors also...
The turbo is well sized...

 

[millsi]

dump is 3.5" with 'semi modded' 5" bodied 100cell cat and a straight through muffler.

fuel pressure is fine (2x 044s into 1x -10 into 2x -8 dual feed rails and a nice aeromotive reg)

 

[JustenGT8]

Yeah 2UZ is pretty well a straight swap....iron block though and 'only' 2 bolt mains, not 6 bolt.

I can supply you a 2UZ block and a pair of VVTi heads if you want to get serious? Same combo that Ed runs for his mad N/A UZ so should flow alright with your turbo bolted to it your current manifolds will bolt up too so nothing to change on your current setup apart from modding the intake pipe to suit.

BTW a china spec IC or a decent one? I have seen china spec cores hurt power and the 1st one on mine was running out of flow around 280rwkw. A good core should be fine though. Still wouldn't account for that wobbly dyno plot.

 

[millsi]

Its a china spec (cooling pro).

Thats unfortunate being a 2 bolts mains. Though i'm still far from deciding on a combo.

why cant i edit my posts to fix up the spelling mistakes?

 

[JustenGT8]

ninga edit paranoia

 

[millsi]

Damn ninja's! Are you still thinking of going lsx Justen?

 

[JustenGT8]

For sure but keen to go with an LS2 so waiting and watching prices. Just another stocky going back in at present and still have the grunter package sitting there waiting to either get finished or get sold

If it sells then it's LS for sure as i'll ditch rego entirely and go all out as a track hack.....lots of freedom then so a full tear down and re-engineering exercise. Hopefully not mega dollars but will take mega time

 

[millsi]

Yeah, casnt go past an lsx. Pity the capacity is too high or i would have gone for that option instead.
Whats the specs on that grunter again?

 

[cribbj]

For sure but keen to go with an LS2 so waiting and watching prices.

If it sells then it's LS for sure as i'll ditch rego entirely and go all out as a track hack.....lots of freedom then so a full tear down and re-engineering exercise. Hopefully not mega dollars but will take mega time

Traitor! LSx's are <yawn> B-O-R-I-N-G

Put a Ferrari 360 in there and keep some spice in your life.

Winning all the time with that LSx motor and never having to work on it is eventually going to get boring, you know.

 

[JustenGT8]

Yeah, casnt go past an lsx. Pity the capacity is too high or i would have gone for that option instead.
Whats the specs on that grunter again?

all the fruit mate Argo Rods, custom SPS forgies, ARP fastners throughout, cryo and nitrided crank (and you have the ARP head studs already ). Build sheet from a WRC engine builder and he put ALOT of effort into getting the clearances spot on.

I have the VVTi heads, for flow, to go with it and a set of 2UZ cams to simplify life ie don't run VVTi and i was sending them to Waggot for the required mods and a mild regrind. Full gasket kit etc and all your existing bits will bolt right on.

Happy to haggle

 

[JBrady]

I second (third?) the valvesprings as likely being blown off their seats.

The 1UZ block is NOT your weak link. Your transmission will go long before the block. Keep the light weight block and maybe upgrade to VVTi heads and intake manifold. Someone HAS to solve the oil supply to VVTi situation. Look at the 3UZ making 370rwhp (276rwkW) on 7psi posted in this section.

I have LONG been a supporter of the LSx options. I would choose the LS3 as the best potential. That said ALL of that has changed with the release of the new FORD 5.0 32v. For the price of building a new motor you are in the ballpark for a crate Coyote that PowerBlock dyno'd at 469hp stock.

 

[millsi]

Do the vvti heads have the same intake and exhaust port spacing as the non vvti heads?

 

[JustenGT8]

Same exhaust so your stuff just bolts on...that's why i went this way originally as i wouldn't have to stuff around.

Inlets are different but i have all the intake gear to go with the heads. Unlike the non VVTi intake the VVTi one is pretty good and i'd have no hesitation in just using that. I also have upgraded valvesprings ready to go in for the VVTi heads so you'd get them as well.

I was building this thing to run a very lazy 350rwkw on E85 on 10-12psi and be responsive as hell. For dyno days and/or the drags i'd just turn the wick up to 450rwkw It's the optimum package in my view out of all the UZ ways you can go?

and JB, i wasn't hugely impressed with those numbers? They are solid for sure, but i made 265rwkw on 6.5 psi with the early UZ and as much as 333rwkw on 10psi. With the VVTi heads, that guy should be making 300rwkw on 7psi...maybe not enough turbo?

 

[XR8tt]

If not valve springs ??
It would be tune or boost leak some where...
Upper rpm and boost .. It could also be spark blow out ???
Closing plug gap helps.. Std is around 1mm .. Boosted .8mm gives stronger spark...

 

[millsi]

I was assured spark was good as it should be with the new ignition setup.