74goldtarga

I have asked this question before and never gotten an answer, I don't know if it is because people are afraid to answer, or they think it is a dumb question, or they consider it intellectual property, or they think they don't like me, or what. But I still want an answer so I'm going to ask again.

What boost level are you running on track? - (I mean road course not dragstrip)

Basically I want to get some consensus on "safe" boost levels in the track environment. Obviously every car, track, and driver are different so safe for one situation may be unsafe for another. Let's assume that the tune is good, not overly aggressive for the fuel. Please specify the fuel used with the boost level. I would love to hear answers for 92 oct, E85, and 110 race. If you want to say why you chose the particular boost level that would be helpful too.

For now I will be using a mix of 92 octane and race gas and will be running 14.5-15 psi with the M-tune / K27/8 / EBC / and new motor. I don't want to run on the ragged edge with my new motor but I did all this stuff to the car to get some more performance so I want to enjoy it too. Trying to find that happy medium. Obviously sustained boost lap after lap is different than a quick blast on the road / dyno / dragstrip so I'm hoping to take that into account.

chrenan

I run stock boost control.

DanaT

I have run 14 to 15 psi for years with no problems as long as you dont lean it out AND I think better headstuds really help.

Van

What if we know we don't like you??

Just kidding. When I first got my turbo S, I blew two head gaskets on the track running the Autothority chips.

After that, I club raced the car for 8 years at stock boost levels and never had a problem.

slivel

In my opinion it's not the boost levels that will kill the engine, it's the tune. If you are at safe AFR's at whatever boost (within reason) you are running, you should be OK. Your head gasket should be the relief valve and will blow if you get too lean, further lean can hole a piston so for track duty a wide band gauge is important.
More important than keeping boost levels down is keeping rpms down. At the track, if you shift at redline every time, you are tempting the #2 rod bearing fate. For longevity of the engine, short shifting at 6000 rpm will get you farther down the road between overhauls and spun #2 rod bearings - and almost as much fun.
I have tracked an 86, with a K27/8 at 15 psi with no problems at all - on pump gas. And this was on the very bad Autothority software. So if you have good software and run a pump/race fuel mix, 15-18 lbs boost should be no problem. The K27/8 doesn't heat the charge as much as a K26/8 would and is safer in the higher boost regimes - but I wouldn't wind it tight every gear. Enjoy.

400hp944

I have been running 100 octane and 17 psi for 3 years without a bit of trouble. I'm at 11.0 AFR @ WOT. May be a bit rich but I have had zero problems and the car hauls ***!

95ONE

I'm convinced Sid is correct that cylinder bore walking is the issue. I think at lower boost levels like 12-15psi is from a bad tune. Higher, I think you will need more than a good tune, like head studs. More certainly, you will just need more headgaskets. Unless you sleeve the block or go to a 3.0 block, it's just a part of life for the car. So to answer. I think I ran between 15-17psi at the track. I blew a headgasket.

400hp944

My block is sleeved (104mm bore) and I use a Cometic head gasket.

74goldtarga

So if one has a stock block and a good tune and cooling and keeps the RPMs at 6k and below and limits boost to say 15 psi, that would be a good balance between power and reliability.

95 ONE - sounds like cylinder bore walking is the limiting variable unless you have a 3L or some other block mods and would favor 15 psi (or so) or below

My block is o-ringed with wide fire gasket but I'm not led to believe that will make much difference. Also, I have a steam vent.

v8killer

I am running 17-18 lbs on E85 with the M-tune.

74goldtarga

V8 killer - that was what I was planning to do but now 95One has me thinking about the cylinder bore walking business.

Oddjob

15 psi on a stock 2.5 block, K26/8, Escort series chips, 3.0 FPR (its running rich, about 11.0 AFR or slightly less), o-ringed block, 100-110 octane. Club raced and DE'd for 6 years w/o issue. The Escort chips have a 7k rpm raised rev limiter, and its not unusual to hit it during races. No short shifting on starts or close in-class battles.

Also bought a car that came out of Eric Steinel's shop that was setup to run 17 psi on a K27/6. Stock 2.5 block, o-ringed head, used both Escort and custom mapped chips, adjustable fuel pressure, recommended to run 110 octane. This car had 10's of thousands of race miles running that configuration.

The original US Escort series Turbo Cups raced in 6 to 24 hour endurance races running in the 15-17 psi range on K26/8s. Documentation that I have indicates they were relatively reliable in those long races when running over 104 octane.

Run it rich, make sure the ignition timing is mapped for a high boost application, and run good gas.

rlm328

I ran 15 to 16 lbs boost for many years with 92 octane. I have eaten a couple of head gaskets. One on the #4 cylinder and the other on the #1 cylinder. The #4 was from steam lock in the cooling system the other was because it took me almost 6 months to get a decent tune.

v8killer

I did have to do my head gasket after 2 years and 11,000 miles (many hard DE miles). The head gasket that went was a Cometic and most of the miles were on the Lindsey 340rwhp kit running 17-18lbs on 100 octane at the track.

Last March I O-ringed the head and am running a Widefire head gasket. Only about 4-5 DE events so far.

hp18racer

That sounds like a pretty good compromise. You should probably upgrade your oil cooler if you haven't yet. I've been running 18 as shown on the gauge in my race car.