KA-T GT35 Build.. cont..

[lrb_2000]

yeah.. maybe we should try to get together some time and run a few times.. maybe up in spokane? I'm not sure how the track is doing up there though.

[idahotuner]

the track is open. and next weekend i am hoping ot run up and do an other dyno then drive out and hit up the track. i need to call and find out for sure. hit up my cell 208-582-1341

[lrb_2000]

Awesome. What are the prices of the dyno up there? I have an appointment for the one down here on friday. It's like $75 for the first run and strapping in, then $20 after that for each run..

[480sx]

Twin scroll is actually going to help spool up tremendously. It will also help top end, really, theres nothing better than a twin scroll manifold they are the sht.

Surprised you hit 12 psi by 3600 with a gt35, must have a great running engine. Any thermal wraps/coatings?

Did Jason have the .63 exhaust housing on his gt35? Seems a bit small to me for 600 hp. GT35's got a pretty large turbine wheel though so idk.. Or is this a t4 gt35?

[lrb_2000]

I thought he meant a twin scroll turbo on a regular T4 manifold lol.. I'm retarded..

I'd say my engine is running good. I have no wraps, but my manifold has some coating on it when I got it.. I think? It doesn't seem to get too hot. When I make my 3" downpipe i'm going to wrap my whole manifold, and downpipe.

You're right. I think Jason has the .82 ar exhaust. We'll see what I can get out of the .63... I'm hoping for 500whp at some point. Friday will be the first time i've been on a dyno though.

[idahotuner]

75 dolalrs got me 4 runs on the dyno up here at ptr. be sweet if we could go up and dyno the same day. i got the guys number if you want it. they were both awesome to work with

[nissan_star]

how did the dyno go? update?

[lrb_2000]

No dyno... I turned the boost to 15psi and it when it hits boost it starts to go really lean like, 14-15afr. I'm not sure what's causing this. It acts like something is maxing out maybe?

I have a walbro hardwired in, 300zx tt fuel filter, 810cc injectors, z32 maf.. so all of those are good for 500hp.. I'm still using my stock Fuel Pressure Regulator though, so that might be the problem? It ran 10-12psi fine... I'm going to check for injector leaks, and buy an ajustable FPR. Stock FPR is 34psi, so maybe it's just not running enough.. anyone have some help?

Basically, I floor it, afr's are fine, as soon as it hits 15psi around 4400+ rpms the AFR goes really lean. I haven't taken it much past that, I don't wnat a blown motor. I'm using 92 octane, and an emance ecu. He said it should be good for 20psi on pump gas. Jason also said it could be my FPR, does that sound right?

[nissan_star]

did it do this before 15psi? and does it do it only at 15psi or does it do it now at lower psi when it used to run fine?

[nissan_star]

did it do this before 15psi?

[nissanfanatic]

Are you on a stock internal engine? If not, what compression ratio are you running?

20psi on pump gas is 8.5:1>* range with 93 octane. You are not maxxing your fuel system either. I run 14psi daily on my car with 740cc injectors and an Enthalpy ECU. I have run it up to 32psi.

[lrb_2000]

No, the engine is fully built. I run 9:1 compression pistons. It only does this when I start to up the boost from 12psi.. so 13psi-14psi it slowly starts to lean out more, 12psi it stays at 11.8ish afr.. So maybe I just need to put in some 100 octance and see how it does? I have my plugs gapped at .34 ... maybe I should gap them lower, but how would that help?

[nissan_star]

can you adjust the tune to help?

[lrb_2000]

I personally can't. But I doubt it has anything to do with the tune. I think it's the FPR if anything. It might not be giving it more fuel pressure as the boost rises?

[idahotuner]

stock fp o na ka is 34 psi that sounds low. on an sr stock is 43.5

[nissanfanatic]

Maybe it just isn't tuned properly. I am running a hardwired Walbro and a stock FPR. I really like having an SAFC in the car for fuel adjustments. You could put a cheap fuel pressure gauge on the car.

34psi at idle is fine. The FPR is proportional to manifold pressure, so with vacuum, fuel pressure will be lower. As long as it reads around 43psi with no vacuum, you are fine.

[lrb_2000]

That's the thing.. On my SAFC, I can run 0 or +50 and it doesn't change the AFR in full boost. That's why it seems to be maxing out something... Could it be an injector leak or something of the sort..? Or would a boost leak cause this?

[idahotuner]

a boost leak would make you run rich

[nissanfanatic]

Is there any misfiring or loss of power? I would look into ignition, or monitor fuel pressure.

[lrb_2000]

no, it feels like it gains power.. much faster than 12psi. Lets say 12psi it is about 11.8 afr.. 13psi 12.5afr... 14psi 13.5 afr... 15psi it starts to go up past 14afr.. that scares me so I let off..

There's no misfire. If i held the gas it would keep going.. I haven't messed with my car for about 2 weeks, so it's pointless to keep posting and not trying to fix it lol..

I'll go over thursday when i'm off work for the weekend and mess with it. I'll gap the plugs down to like .028 instead of .034, I'm not sure what that will do though.. I'll check the injectors for leaks and replace the fuel pressure regulator with another stock one. ..

I need to get an aftermarket fpr and gauge to check the thing.. if anything i'll just run 12psi for now until I figure it out, no big deal.. it still halls ***..

[daconkiftador]

did you get anything figured out?

[lrb_2000]

nope. I thought it was running better the other day at 14psi but I guess not. Took it out this morning and the AFR's jump back to lean. I gapped the plugs down to .030, set the timing right at 20*btdc.. I guess I should get a new fpr and see what's up. Maybe it's the ****ty gas around here with 10% ethanol. I should get some octane booster or something.

[480sx]

Its def not the gas! 95 percent or more of all gas in the us is 10 percent E.

Hook up a fuel pressure gage to see whats goin on.

[daconkiftador]

whats the word?

[lrb_2000]

I moved my maf away from the turbo, down into the fender.. That pretty much changed everything. I'm actually able to run off the ecu tune now, and not have to use my safc. I was taking away over -15% across the map for some reason.. So it's running good. I think this fixed the problem with it leaning out in boost. I still need a fuel pressure gauge to check that though.

[shift76]

I moved my maf away from the turbo, down into the fender.. That pretty much changed everything. I'm actually able to run off the ecu tune now, and not have to use my safc. I was taking away over -15% across the map for some reason.. So it's running good. I think this fixed the problem with it leaning out in boost. I still need a fuel pressure gauge to check that though.

sorry to kick start a dead topic . . but I am having very similar issues with my ka-t . . why would the placement of the maf change the way the car runs so drastically ?

[Chris28]

sorry to kick start a dead topic . . but I am having very similar issues with my ka-t . . why would the placement of the maf change the way the car runs so drastically ?

Because at higher boost the spinning turbine creates a vortex effect that messes with your maf. If the maf is further away and preferably after a bend then you reduce the chances of the "disturbed" air giving your maf a bad reading.

[chad b.]

Correct me if I'm wrong, but I seriously doubt a stock KA fpr is a rising rate. Those things are made to run off of vacuum, not boost pressure. Man, I can't believe I'm reading this and noone said anything. You need a 1:1 rising rate fpr, like an aeromotive. It doesn't matter how much tuning you do with the injectors or the MAF, if the fuel pressure doesn't go up with boost, then your rail and injectors will not have the pressure needed for the flow that you are tuning.

[idahotuner]

dude we are getting an allwheel drive mustang dyno at my school in walla walla if your still wanting to dyno. it should be installed pretty soon.

[eazye2000]

Correct me if I'm wrong, but I seriously doubt a stock KA fpr is a rising rate. Those things are made to run off of vacuum, not boost pressure. Man, I can't believe I'm reading this and noone said anything. You need a 1:1 rising rate fpr, like an aeromotive.

Stock KA FPR does rise in pressure as boost rises.... It has a diaphragm in it that reacts to vacuum and boost.

BUT...

It is not consistent. I ran my stock FPR for a while with 370's at 12psi with no issues. Not to say it's the right thing to do, but it worked. Ran over 72psi of fuel pressure at 10-12psi of boost.

I would say a stock FPR, is somewhere between having a 1:1 Rising Rate FPR, and a 8:1 FMU. It's all over the place in boost... Not consistent.

That said, it's still not the right thing to do. I've lived and learned along the way to having what I have now. Take this information and do what you will. This is personal experience.

Drop 75-150 bucks on a name brand RR-FPR. You wont regret it. I don't recall if you built your motor, but it's worth the security regardless.