Duke

Yes, proper engine management is one of the key issues. Other issues are the stock 951 components such as camshaft, turbo etc.

I'm going to wire up my new engine management (full stand alone) with a full ignition retard table based on a filtered knock signal, a full table for enrichment based on EGT etc.

toddk911

I know Dave L told me he runs 23psi on a daily basis on pump I beleive.

John, have you seen or have more details on Dave's personal 951? I know he runs the Super 75, but what other mods?

HIGHBOOST

I just want to know how guys are running 20psi w/REVO on these GTI's.

porshhhh951

he basically has the best of everything.

Lindsey Racing Stage III Head.
Lindsey Racing Super 75 Turbo
Lindsey Racing Stage 4 MAF w/Mafterburner
Lindsey Racing Intake
Lindsey Racing Solid Camshaft
Lindsey Racing Dual Port Wastegate
Lindsey Racing 4" Exhaust
Siemens 72# Injectors
Lindsey Racing Street Chips

and yes he runs 23psi on 93 octane fuel everyday all day and never has problems. As it has already been stated its all in the tune. Just as it has always been and will always be. Thats why a standalone car is going to make more hp with the same mods as one still using the DME to controll the car's functions.

I would hope people would know this by now. There have been so many threads covering all the management systems and you always see the big hp guys running SA's. Is it any wonder why

BTW todd the above wasent directed at you. I know you already know this

IanS

I was running 23psi on my 1.8T with a GT28 on 91, but it ran a lot more consistently at 20psi. And my 1.8T has 9.5:1 compression, so its not low compression. I believe the 1.8T ECU pulls timing in 0.5 degree increments up to 12 degrees. Thats a lot of builtin protection. And the Bosch MAF is probably vastly more accurate than an AFM.

But if the aftermarket tuning is junk, you can blow an engine just as easily as any other car. So yes, it appears the ECU + tuning are key to running high boost on pump.

jimbo1111

I have run 20 psi on pump fuel with my current setup.With 93 octane. I wouldn't attempt anymore for 2 reasons. First because there is plenty hp at 20psi and second I don't want to risk destroying such a well sorted car.There was no noticeable ping. Trust me that I know what ping is. When outdoor temps are over 75deg it might be dangerous and close to the edge. on the other hand I would have no problem sustaining that boost under track condition using race fuel. The 951 cooling system is fine and the oil cooling system need some work but that's about it. Believe it or not the 951 is a pretty reliable track car.

Driftomagnifico

Knock aka Detonation is when the flame front propagates too quickly and creates a very sharp rise in cylinder pressure before optimal. This pressure stresses piston rings, ring lands, rods, rod bearings, and the crankshaft. Bearings and ring lands are typically the first to go. The damage to major components is from pressure, which is based upon the heat created in the explosive combustion.

You are thinking of pre-ignition when the latent heat of the previous combustion created a hot spot in the chamber, and the mixture is then ignited prematurely. This creates the early rise in cylinder pressure but typically the peak value is a fair amount less if the mixture is correct. Has alot to do with the placement of the ignition source to determine the efficiency of the burn.

Driftomagnifico

If you want a more basic explination of how they can run 23 PSI to the 951's 18 PSI then look to the amount of torque they produce compared to the 951 and the engine's dissimilar properties (higher CR, etc.). Torque typically is a good way to measure peak cylinder pressure, and will give you a good idea of how efficient a chamber and tune are.