turbo and WOT injector/K24 vs K26

[Todd Phenneger]

My boost threshold is really ~2500rpm. My point about pulling from 1800rpm
in 4th was just to illustrate the torque of the motor, but there's no boost
at that rpm. Between 2500-3000, I get 3-5psi boost and acceleration isNo worries, I never assumed you had boost at 1,800.  I just found it odd with the High Compression motor you got boost so Late.  I get about 2psi at 2,000 RPM and it goes up from there.  Probably 3-4 at 2,200 and by 2,500 I've got about 5psi.  BUt I dont reach full boost (8ps or higher depending on WG setup) untill maybe 3,500 or so.  ANyhow, my k26 has the smaller hot side that supposedly spools quicker.  I think the same hot side as the RS-2.  So I think I'll use this and try to build a Pseudo RS-2.  We'll see how it works.  Mine spools faster than a k26 but not as fast as a k24.  Good compromise if I can get it modded for some real power.  But first fuel.  Hopefuly that will be solved this week.
decent, but it's 3000-3500 where the boost really starts to build. With the
short gearing of the 4000Q, spool-up is not really an issue, as I rarely
drive the car under 3000rpm anyway. The power range is really 3500-6000rpm.
Even at 70mph in 5th gear (3500 rpm), throttle response is immediate and
there is no need to downshift to pass. What I really need is a 6th gear.
Yea, I know that feeling.  I have an 84' with the even shorter 4th and 5th gears.  I get 4k rpm at 80mph.  I think thats right.  VERY close to that anyhow.  Now with all this power I'd kill for an extra couple hundred RPM.  But for the Rally car it will someday be its perfect. :-)  I guess thats why I bought the ur-q.  Its got the long gearing which will be nice on the Highway.
With the Profec boost controller, boost builds quickly, but I still don't
get full boost until the higher gears when the motor is really under load..
If I set the high boost to say 17psi, I will get only 15psi in 1st-3rd, but
17psi in 4th & 5th. And the turbo will hold the 17psi as long as I stay on
it. Attempting this with a K24 on a 10vt will produce a lot of heat but no
power. Hmm, I do plan on using the ProFec when I'm ready.  But I need to be able to get a solid 8psi with OEM equipment before I'm happy.  It must be the HIgh compression we have.  Do you think?  I've known a few MC-1 engines that turned 20psi on just the CIS and weren't leaning out.  They were P&P'd, with cam, etc.  Drove one the other day.  SO all I can guess it that highercompression needs more fuel that causes us to lean out sooner.   Grrr.
Yes, my original K24 was better immediately off-the-line, say from 0-15mph,
but who cares? As you said elsewhere, though, the K24 works like a charm on
a relatively stock or chipped 5000TQ. Yup, and on the 20vt motors for some reason.  Not sure why the High Compression 20v's take the k24 so much better but thats really what it was designed for I think.  It will hold 26psi on that motor.  LOTS of power.  But thats pretty well taxed.  Needs a good IC>
Also, I don't understand how the K24 works at the boost levels people are
running on UrS4's with K24's. Granted there is a big difference in cylinder
head, intake and exhaust manifold design between the 10vt and 20vt, but
what about compressor efficiency, pressure ratios, etc of the K24? On my 92,
which is pretty much stock except for a Hoppen stage 1 chip, the boost peaks
at ~21psi and then drops quickly to ~16psi. I know this only from the boost
gauge, as the power is not really very impressive (could be the 2+ tons).
Still, I worry that the K24 is going to overspin and self-destruct at these
boost levels at 5000ft. 
   Heh, great minds think alike.  I'm not sure why.  As I said, my roomates 93' S4 is runnign a NED Stage 3+ with 26psi and the stock k24.  It does have trouble on hot days but when the weather is right it will hold 26psi sometimes all the way up to 100+.  We pulled a new C5 Vette the other day.  He must have been in the wrong gear but still.  Pissed him off, thats for sure.  He drags Adam about twice a month, add a chip and now the playing field is more level.  But he still needs that turbo and RS-2 manifold to really challenge him.  Oh, and RS-2 injectors. :-)l8r  TOdd

Todd Phenneger
    83' ur-q (awaiting a 20vt)
    84' 4ktq  fun but I'm sick of CIS.


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