Ahmet

I second this, I run my k26/6 @17 psi right now, had it much higher than that, no problems on pump gas... The amount of pressure in the intake manifold is just one variable determining what can be done on pump gas...
Ahmet

crazyracer

I ran 18 PSI with 93, if I go higher I would mix with 10 or 20 % Xylene.

AlexE

I ran 18 psi with 91 ............with 20% xylene......

and no BOOM

TonyG

I'd run real race gas if I need better fuel to support the cylinder pressures/temps/timing.

Black Arrow

What I ment was, will the gasket hold 20-25 PSI? I`m going to do major things with my 951, so it isn`t like I`m just a newbie that will have much hk and do nothing! I`m just wondering about what the original car is good for.
Sorry if it`s hard to understand my poor norwegian/english!

emwporsche

I always run around 17 - 19 psi on pump gas
though I do have the kkk 27/6 w/ shim

though I did just find out that most 76's sell 110 octane in the US
just have to ask, I think I'll try it!

do I need to adjust the proM if I do usae 110 octane?

stewart951

Silly question,

But I only see talk of the Vitesse/Guru upgrade. Why no talk of the Lindsey 363 RWP kit available now. Doesn't anyone use it ? Does it perform as advertised ? Is it truly a bolt on with no tuning ?

Question #2 - Running 105 octane unleaded race fuel, if you have the right AF ratio, can the head gasket really take the cylinder pressure of 20-25 psi bost for endurance racing, or only short bursts on the street ?

If you have carillo rods, rich enought AF, can the engine live at 20-25 psi for a few hours at a time (1-3 hour enduros) ?

How much exhaust temp would I expect ?

My engine is stock currently except for good rods.

TIA,
Stewart

crazyracer

I have a wide fire ring head gasket, so I don't know about the stock head gasket. I ran 25 PSI with 93 plus 15 % Xyline without problems with my 27/6.

pk951

Yes you can run at 17psi to 18psi on pump gas, but it's just a matter of time before you blow a head-gasket. Read past threads, there are plenty of blown headgaskets. Why because people turn up the boost on cars that have over 100 000 miles on them, and some. when someone is running a 26/6 turbo, and they turn up the boost to 17psi or 18psi that turbo is out of it's efficacy range. the air going into the engine is way to hot good for blowing head-gaskets,plus turbo is spinning way to fast wont last to long.

stewart951

so if I have a good head gasket, rebuilt engine and the correct air fuel ratio, the engine will live a long time at 20-25 psi ?

Stewart

PS - What about the question on LR 363 kit ?

Matt H

Danno has chips to run 18 psi on stock parts and non-race gas. Just ask him. It is my plan too. Turbo will be out of efficiency range above 4700 (I think) RPM. I believe that the max power will be the same (limited by the Turbo) but there is a bump in mid-range torque. Should know soon enough, just gotta pull the engine and reseal, will report then.
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crazyracer

"Danno has chips to run 18 psi on stock parts and non-race gas. Just ask him. It is my plan too."

I remember him posting that he does not recommend more than 15/16 PSI of boost with pump gas, then somebody came and asked him: "But could you prgram the chips for 18 PSI?" He finally gave in and said "yes I can program anything". I am pretty sure that he did something to timing on the chips.

So what's the big deal? I think it's out of discussion that the higher the boost, the better gas quality you need. What does high boost mean for your engine? Of course it has an impact on the life of it. How much depends on how you drive, maintenance, of course condition of your engine, head gasket (that's why they have the new metal ones) and many other factores.

As I said earlier, our cars are old (mine has more than 100 K miles on it and is an 89), anything can break anytime.

That's why I was looking for a turbo kit which provides as much HP at low rpm as possible (called torque), that's why I went with the vitesse kit and spent the extra 200 bucks for the ball bearing upgrade. I have no intention running higher than 18 PSI of boost, I am happy with 400 plus fly wheel HP, wouldn't you?

Skip Wolfe

Higher boost itself is not that destructive IF your fuel system is correctly setup. While an old almost ready to go anyway headgasket or engine component may very well let loose under high cylinder pressure, cylinder pressure itself is not very stressful to the engine. The problem is the increase risk of detonation. The detonation is what typically blows headgaskets, breaks rods etc, not cylinder pressure. Now there is always the risk of the head lifting under high pressures but this can usually be solved with a good set of head studs.

The detonation is typically caused because:

A.) people are running their turbo way off of its efficiency curve and it is really heating up the intake charge,

and/or

B.) they have not modified their fuel system to keep the AF ratio in the range.

The reason Danno was probably reluctant to map a chip for running a K26 turbo is because it the k26 will be way out off of its curve, and heating up the air charge consequently showing minimal hp gains for an increased risk of detonation. And I'm sure that he was worried that if someone ran that configuration and blew the headgasket or worse they would go after him for having a poorly mapped chip when in all actuality it was a high risk configuration to begin with.

As far as octane rating goes, while it does provide an increased measure of protect over detonation, I think most people use it for a crutch

It is incredibly important to keep an eye on the AF curve and my advice to anyone is to make sure they tune things in or at least verify the AF curve on a dyno. As long as the AF is good to go, higher boosts are very much possible.

FWIW Corky Bell's book Maximum boost has some good analysis showing the stress calcs of the rod etc. for running higher cylinder pressures and how it is almost negligible when compared the stress the rotating parts realize from increase in rpm.

pk951

What would be a good idea is install an EGT gauage, that is even better than those gauges they sell to monitor you're fuel mixture,gases get to hot you're goinging to be set with problems eventually.

stoked944

wow, this has turned into a very informative thread for me. oh and i didn't know the vitesse kit had a ball bearing upgrade, thats good.