Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[flat_black]

Im trying to figure out why im not making as much power as i should be.... im thinking its because the wastegates are recirculated at such a dark angle but some some people seem to disagree some people seem to agree, just wanna know what you guys think...

it has twin gates in case your wondering

car makes 400whp and 376wtq at 20psi on pump gas... turbo is a 3076r with a divided 1.06 housing

Motor is an RB25 GTS-T skyline engine.... ( 2.5 inline 6) these engines seem to generate a simular power band as a b series honda they dont generally drop torque like that and the horsepower doesnt normally level off like that...

[ifly87]

I cant see that making a big difference, either way looks like some real nice fab work.

[bigdaddyvtec]

- 30 whp

[lsone_chevelle]

not a gate issue

[Eggylshatch]

Probably would help a little to have them at less of an angle and further down the downpipe, but I doubt thats what is really holding you back.  I'm no expert, but it looks like you have some kind of restriction, or tune is fucked.  Weird how early it levels out and just kinda bounces around.

[fastspec2]

was the pull done with the exhaust hooked up? whats the inlet look like? (filter and what not)
Do you have a logg of the boost during the runs? It looks like it just runs out of air.

[flat_black]

The exhaust was hooked up its a full 3 inch setup, we removed the air filter from the turbo and power didn't change a bit... Boost was consistant at 19-20psi..

[danz]

stock cams?  might be your problem...

[bigdaddyvtec]

People make more than that on stock cams on similar setups.

 I GUARANTEE the recircs are hindering the issue...  Id put money on youll make more with them "open" The setup is SUPER clean and theres NO cutting corners on it...  It should make more as it is. The cams arent it.


Would a set help? Surely, but thats not whats holding it back... Something is awry and the recirced dumps are NOT helping it. Sure sounds nice.
Car is SUPER clean too.

[Joseph Davis]

Those dumps won't hurt anything.  I've seen crappier manifolds with sharper and shorter re-entries on a B-series motor (your comparison) breaking 400 by 15-16 psi.

What are you tuning it on?  And, my experience with stock cam RB25's is they continue to pull harder and harder especially past 6K.  Your dyno sheet's smoothing is on 5, and past 6K the power output levels off and gets all sorts of lumpy.  I see that on other motors when the cam timing is not ideal, or you might have a boost leak manifesting ie - BOV coming open, coupler allowing boost to leak off between itself and the charge piping, etc.

[flat_black]

Those dumps won't hurt anything.  I've seen crappier manifolds with sharper and shorter re-entries on a B-series motor (your comparison) breaking 400 by 15-16 psi.

What are you tuning it on?  And, my experience with stock cam RB25's is they continue to pull harder and harder especially past 6K.  Your dyno sheet's smoothing is on 5, and past 6K the power output levels off and gets all sorts of lumpy.  I see that on other motors when the cam timing is not ideal, or you might have a boost leak manifesting ie - BOV coming open, coupler allowing boost to leak off between itself and the charge piping, etc.

Yeah on lower boost peak power comes at redline (7500) and the power curve looks normal, however the more boost the more the horsepower levels off it seems... when i built the downpipe, and recicred the wastegates i didnt really think it would hinder it much, but ive heard both sides of the fence on the issue.. it seems like a restriction to me just because of how the power levels off on higher boost and the compressor having alot left in it. ( i know i forgot to mention that in the OP)

I need to change the wg springs, boost wouldnt hold anything above 20psi it would spike to 25-26psi and fall, i was having some breakup on higher boost but increasing the dwell pretty much eliminated it... maybe its was missing ever so slightly??

You think cam timing could be off a tooth? i wondered this myslef, but i thought it would have a much larger effect...

Im running a New Haltech platinum pro its a fairly new unit, seems pretty soild to me, Dave liked it too

[Joseph Davis]

Sounds more and more like a leak/restriction somewhere.

Just to be perfectly in the clear... this is a T3 footprint, not a T2?

[flat_black]

its a T4 1.06 divided ATP housing

[Joseph Davis]

They found a way to cheese a T4 housing on a GT30?  Cool, that should support plenty of power.

[flat_black]

Yeah, its fairly new... i guess it spools pretty fast... had boost controller issues on the dyno so thats not a good reflection of how it spools...

3rd gear roll ons i get 20psi by 3500rpm..

[DRQPQUT]

mitch, wish i could be of some use but i cant..on another note your setup is fuckin hot to death though i like 2 big thumbs up ...btw your slow

[flat_black]

I didnt know youve even seen it??

Your right my car is slow, but not as slow are yours, once you learn how to drive you might be able to get past the 240... but never the prelude.... 

[DRQPQUT]

we will find out this summer thats for sure...i saw your 240 the day i gave you those gear sets ...by the way i need those back, for my back up tranny..cuz after i walk you, and break my tranny i will have another to slap in

[bigdaddyvtec]

His car is faster than the prelude right now in reverse. Quit talking shit... You have nothing. 

[j.h.christ]

you are all african american

[caged]

What inlet manifold and TB are you using?

[crxvtec91]

Send mani/tb to have him rework it :yes:.

Im with JD sounds like a boost leak. soapy water is your friend!

[Joseph Davis]

Yup, cap the turbo inlet and pressurize the system with shop air.

[flat_black]

using greddy knockoff manifold and q45 90mm throttle body

[Joseph Davis]

I thought Q45 were 80mm

[caged]

Inlet is 90mm and tappers down do 80 somthing mm's