clouddomino

Not desputing that at all, just was trying to get input from people who are/were running 21+ psi... So does anyone have any idea of possible way's to run massive boost off pump gas without detonating the engine???

lart951

I am running 21psi but I add 15-20% xylene to the 91 pump gas.

Rogue_Ant

Sure, an efficient compressor, low turbine backpressure, minimal cam overlap, cool intake charge will all help. Otherwise you can add more fuel, and pull ignition timing. But there is a limit, just what that limit is depends on each individual setup!



Rogue

DDP

WATER INJECTION!!!!!!!!!!!

lol

clouddomino

So it's possible. To be quite honest I'm ill-experienced when it comes to forced-induction. Prior to my 951 it's just been my 944 n/a and drag cars with big displacement. But as far as power adder's go I'm familiar with nitrous and run it on my drag camaro and advance the timing quite a bit with the methanol blend I'm using. So any insight on tuning and timing advance that applies to turbo cars making more boost is great info for me.

Porschefile

Sorry but, you're wrong. Efficient heads and combustion chambers play a large part in that being possible. My friend with an Evo8 was running 23psi on 93 octane, daily drove, auto x'ed and road raced the car for several years, and it was still running good when he sold it. I've seen plenty of other people running as much as 25psi on pump gas. It's all about efficiency. Our motors have horribly inefficient heads compared to modern stuff like Acura RSX and S2000 heads. Water/alcohol injection definitely helps and will make it possible to squeeze a few more psi out on pump gas. I doubt if you will ever see any 951's running 25psi on pump though without running water injection, aftermarket ems, or some other more involved stuff.

Clouddomino, the LR Super 65 and Super 75 are "big" turbos for what most people seem to be looking for. A Super 75 with a stage 5 turbine and larger hotside (probably ~#10 or T3 .82+) is large enough to break 600whp. That's overkill. How much power do you want?

20psi on pump gas
25psi on pump gas
20psi on pump gas
20psi on pump gas
I can find examples like that all day long. Your not likely to see many people (if any) going as high with our cars though as the head poses a huge restriction. Water injection, aftermarket engine management (good advanced stuff like AEM, Autronic, Motec, etc), fuel additives and tons of head mods are some of the basics it will take to get 20+psi on pump reliably. In short, things that will reduce the potential of detonation.

clouddomino

I'd love to have a 500 rwhp daily drivable 951 but it seems that pulling horses out of these engines is much more difficult than that of a large displacement car. Or something with modern electronic and engine management systems. I've seen many daily driver muscle cars with 500+ rwhp out there. And with mininmal bolt on's and timing advance I've gotten 500+ out of my camaro. And with the nitrous set-up at a 100 shot I'm running an 11.18et, and a 11.82 w/o nos. With detuned advance and 93 octane gas, I can still put down a 12.10. So what are the major restrictions that we are faced with as far as pulling serious horsepower?

2bridges

hahaha - porschfile I was waiting for a response from you.....

I think what is overlooked are two things.... pump gas with additives IS NOT what clouddomino was asking about... and is not pump gas. He was also asking about safe boost, not razor's edge tuning to the absolute ragged edge. Why folks do this with pump gas on street car, absolute silliness.

To run boost 20+ and tune by backing timing until detination stops on pump gas. Wait till you get a bad or different mix of gas.... people that go this approach I can only think are not really using their head.

Rogue_Ant

I agree... if they don't have a way to monitor knock in real-time. However most EMS can be configured to display a warning if excessive knock is present.

I.E. my friends Eclipse displays a check-engine-light if the engine has to pull more then 3degrees of ignition timing due to knock.



Rogue

2bridges

I hear you rogue -

Funny - excessive knock........ I consider ANY knock excessive knock. Preignition is absolute punishment to the lower end. I tune on the side of longevity and safety margin. Then when changes occur (elevation, humidity, fuel quality) I don't have to stress

Rogue_Ant

Yeah, we do tune for zero knock. Some engines are can withstand knock better then others. Also from what info we've gathered on the knock thread, even stock cars will knock some, as is the case in any boosted factory car I've seen/tuned.



Rogue

clouddomino

So as far as safe boost (boost that won't in any way damage the engine or drivability of the car) 20psi is pretty much the max for pump gas, is this the general concensious???

2bridges

for me 18 is about the limit I will go on pump gas without additive.

I am more reserved than some, but I guarentee when **** comes apart on me is in not because I was an idiot wih my setup and tune

One other aspect - is you never start with a high boost to tune. You will want to start lower and get a good base tune before you slowly turn it up

clouddomino

So it's pretty much the same as any power adder. Start with something that won't disrupt your system and tune up to the max of 18-20psi, depending on your set-up. So for 18-20psi of boost with maf, full exhaust, and ebc what would be the recommended chip set to go with?

ehall

Vitesse.