Ahmet

Mods: Chips, wastegate shims/vacuum port disconnected, 3 inch open exaust turbo back.

Boost (rolling on from low rpm)
1st gear tops to ~12 @ ~3krpm drops to ~11 by redline.
2nd tops to 14.5 @3500rpm, drops to around 10 by redline.
3rd tops to 16.5+, drops to around 11@ redline.
Haven't tried 4th or higher.

The car has ~138 +/-1psi for all cylinders, new plugs, cap/wires, rebuilt injectors, new vacuum/boost hoses (no really, almost all of them ). Aside from "using" an absurd amount of oil (it smokes sometimes) it runs top notch.

Side stepping the brake while at full throttle will produce about 14psi in 1st, but around 18.5+ psi in 2nd (~3400rpm). It also seems to pull much harder in 2nd. I know this is supposed to be normal since higher the gear, higher the load but...

Today it was ~96 degrees, the last time I drove the car hard it was more like ~72 but the car didn't have shimmed wastegate, and could hit about 17psi sidestepping the throttle at 3krpm. The performance level seems about the same, if not today's performance slightly worse.

Now the questions:
At what pressure will the K26s get really inefficient, with an open exaust? I like how the car pulls when boosting 17 psi, but is this turbo not capable of delivering that without sidestepping? I'm willing to do some custom piping and get rid of the AFM +straighter/larger piping, but I'm not spending the dough to install an MAF just yet but that boost falling off is getting very annoying...

I have the flow rates of the injectors if anybody is interested, I'll post pictures of the progress on this turbo soon after I dyno it. I should probably go to bed now, my last final starts in 4 hours...

Questions, answers, comments welcome.
Ahmet

rage2

K26/6's are terrible after 5000rpm. I hated the boost drop. Tried everything to get more boost up top, but it was impossible. Bigger turbo fixed the problem nicely =).

Russ Murphy has a K26/6 (I think) with SDS in his car, so zero intake restriction. I don't know if the boost is higher with this setup (Russ?), but for sure there's a lot of power gained at the same boost levels with no restriction.

Danno

"I have the flow rates of the injectors if anybody is interested,"

Yes please...

Russ Murphy

I'm afraid the answer is "I don't know". But I assure you I'm going to find out. The head (Garrity) is on and I'm finishing up. I still have the stock injectors at the moment, but will have the 72lb Siemans shortly. I want to drive the car with the old injectors and new head firsst and see if my fuel numbers have to change and see if they now look more like Rage's stock injector numbers. My gut feeling beforehand is that I won't see boost any higher (or as high maybe) than Ahmet has now. I'll just be way faster at those boost levels, a la Rage. To date the highest boost I've seen is 14psi in fourth at 90-95mph (5000 ish rpm?) That was an accident.

Luke

I dont think there would ever be any benifit to running over 17lbs with a 26/6.

Ahmet

Thanks for the replies guys.

Rage2, I think I'll go for a large turbo at some point but right now I have to worry about a few other things +I'm poor...

Danno, I'm moving today and my scanner is already at the new house ( I don't even know how long they're going to take to hook up roadrunner), I'll type up some of the #s though:

Injector type P&H: 4.9 ohm
Injector part No: 0280150803
Injector make: Bosch
Test pressure: 43psi
Test pulse: 6.0 MS
Gravity Weight: 0.75
Volume Test (After rebuild):
127.7 max/125.1 min cc per min. (across 4 injectors)
one of them was down to 117 when dirty.

He also told me that the same part # bosch injectors flowing vastly differently was non-sense. That correctly functioning clean injectors of the same type should flow almost identical. Went onto say that these injectors handled higher pressures nicely, and suggested to not upgrade until I'm looking at 320+rwhp.

Russ Murphy: Please let us know how your car does when it's back together, and good luck.

Thanks again for the replies.
Ahmet

Danno

"He also told me that the same part # bosch injectors flowing vastly differently was non-sense."

Then how do you explain this?


versus this?

M Danger

hey when that says dirty, do they mean like dirty as in covered in junk, or looks clean, but you cant really see, the dirt?
and if so it this anyting a few bottles of injector cleaner can take care of?

Ahmet

Danno, I don't (can't) explain the difference. I'm only supplying the information I've been given by marren because I thought it would strike your fancy. My guesses would be that the difference is likely to be from differing production tolerances, test pressures, duty cycle differences, gravity weights, and even perhaps difference in flow testing/measuring equipment, maybe test temperature, cleanness of the injectors (I would think that it's possible some restriction is left on even after cleaning) and my most likely guess would be the difference of the density/viscosity of the fluid used for the test. Infact I think we should call these guys up and see what they're using/their take on this. Do you think that's a good idea?

M Danger, I think the dirt build-up happens inside the injector I would guess at the metal screen, the injector nozzles, and perhaps other areas as well. I would not expect to get the injectors totally cleaned with just a bottle of injector cleaner. I think exposure to ultrasonic vibrations is the only way to truly clean an injector. Reverse flow is also done often, as well as pulsing the injector as it's being cleaned. Don't take my word for it though, do a search on the internet, I'm sure you'll find plenty.
Ahmet