B_Rock

has anyone thought about the type of dyno that was used. i'm no pro by any means, but i do know that dyno figures can be drastically skewed from brand to brand, or even if any variables were accidentally set wrong. just a thought. on the street does it feel like its making more than 280?

bcty

throw a set of stockish temp plugs in there.. unbolt your exhaust fotm the dp back and go for a quick drive and see if you feel the 50hp or whatever difference.. pretty simple and easy to unbolt part of the exhaust..

patriick

iTrader: (3)

Better add some fuel to the map if you're going to try something like this. The extra power may be enough to make you run lean and blow the engine (now that Steve Kan tuned it for 280HP).

ptrhahn

iTrader: (9)

Bob,
Per our local RX7 convo on the same subject, Crispy made 305 rwhp @ 12 psi, with a PFS Intake/IC, ATR DP, PFS Catback, stock port original motor, and I forget which computer and cat... but the point is, he had a cat and made the power without significant tuning.

You've got something going on there, and if everyone else in your group made "normal" looking hp figures on the same dyno, i'd say it is in your car... i'd try the plugs first... i run 9's all around even on the track.

The rule of thumb always was that a good mandrel-bent downpipe was worth 20 hp over a stock precat, and a good catback about 15 over the stock exhaust.... so the Racing beat and HKS units would have to be about as retrictive as the stock units to limit your power that much... so i doubt that's it.

From there, i might worry about your turbos, except thjey are making boost and the temps aren't unusually high to suggest they're working real hard to make it.

I'm sorry to say that i'd start looking back at your motor. Did you ever establish how KD came to believe it had a problem, but it never showed up at Chris's in VA Beach? Thats awfully curious.

SPOautos

When my turbine wheels were shot I was down on power enough for my traps to fall from 113 down to around 110 and that was running 1-2psi of boost MORE than I was running when I traped 113.

Your not going to notice a increase in air temps in short runs cause the sensor isnt fast enough to dramatically change in a short time period.

Evenstill, if this wasnt your problem I can still say with 98% certainty that if you had a bad rotor housing there is turbine wheel damage. And again, based on my personal experience of replacing 4 engines and a few sets of turbos and driving around for 6 months with bad turbine wheels I think that is a least part of the problem.

Especially if your power is laggy

STEPHEN

gcthree

Peter:
I know the plugs heat range is troubling people, but take a look at the photo of a plug I pulled, and you'll see that it's right on-perfect light tan color suggesting it's the right heat range. If it were too cold, it would be sooty, with some carbon build-up.
I've also asked Chris to give some thought to the motor, too, although we feel pretty certain the problem does not lie there.
Stephen:
I've been on a flight for the last few hours with not much to do but think about what's up with the car. I'm not going to eliminate the turbos from the equation, because logically, there's not much else to look for. Your experience means alot. What is odd, and Steve Kan pointed it out, that as we lifted boost, hp did not rise at the rate it should have (10hp per 1 lb. of boost). Thanks for the further thoughts.

clayne

Jacking the boost up and having no increase in HP output definitely seems to jive with SPOs theory.

It sounds like the turbos are now doing double duty as an air furnace.

On the same token, it could also point to something still flow related (besides the turbos).

You can generate 60 psi in a silly straw - doesn't mean you're moving much air.

Kevin T. Wyum

Mmmmm straw examples, I love em. Much like String theory, we have instead for 3rd gens Straw theory. : )

The straw will soon hold the place in turbo conversation as the mystical frictionless skating rink of physics 101.

clayne

Hey Kevin,

"How much boost are you runnin'?"



Gotta love it when people ask you that. It just wouldn't have the same flair if people said "What CFM are you flowing?" But, like most things, people need something easily tangible to "measure" and quote back.

P.S.: (since you're here I'll just ask) Any fitment issues with Koyo rad + ASP Race?

Kevin T. Wyum

Good question

Kevin T. Wyum

SPOautos

Is your comment directed toward my example?

STEPHEN

rotaryextreme

iTrader: (2)

You probably have a minor boost leak somewhere. The leak is minor enough that the turbo can still keep up with the boost but then bad enough that it spins to a point that it's out of the efficiency range. You can see 30-40 rwhp drop because of that. Learned it from expereince on the dyno. Good luck.

Chuck Huang

Kevin T. Wyum

Nope, towards Clayne's post directly above mine, he mentioned straws. I love straws in turbo talk.

Kevin T. Wyum

gcthree

Thanks, Chuck. Good suggestion. There's a plate on the side of the PFS Intercooler that might serve as an overboost safety valve, or? I'm going to check that. The rest of the intake tract is solid. I'm using T-bolt clamps on the silicone couplers, and I have an Efini Y-pipe, so there's little chance for leakage in those areas.

cruiser

Maybe you werent measuring on the dynojet dyno ? They are known to give the highest numbers. Mustang dynos give about 15% lower numbers and MAHA LPS systems even less.

I only got 285bhp on MAHA LPS system with the mods in my sig (except for the IC, but the stock one was cold so no difference there) at 12psi. Although the new plugs made some difference at butt dyno (changed them last week), numbers still seem low, as they're recalculated to flywheel hp.

My car also runs fine and is fast. On the track I leave M3 (321hp version) behind on the straights.

cruiser

Is there a way to verify if turbines are out of efficiency range ?

rotaryextreme

iTrader: (2)

I never had a PFS intercooler so I don't know if there is a plate or what kind of plate there is. Sorry, can't help you on that.

Chuck Huang

clayne

Tee the boost gauge into one of the turbo manifold or y-pipe nipples. This will show you actual pre-IC/pre-piping pressure. If you see 20 psi here, and you're seeing 12 psi at the upper intake manifold - definitely a boost leak or brick in the intercooler (which we know not to be the case).

rotaryextreme

iTrader: (2)

Yeah, by looking at the compressor map.

Chuck Huang

cruiser

Chuck, I think clayne got my question

tphan

I know this is an old thread but which was the problem? the HKS DP or damage turbine?

wadejg

I'd also like to know; what was the final diagnosis?

Regards,
Justin Wade

Mr rx-7 tt

iTrader: (5)

Bad butterfly plate I believe...

tphan

is that part of the twin assembly?