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how much boost on stock headgasket


csa
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hmm...guess my dear tuner is sandbagging quite a bit then.

 

well since we're at it. what would you recommend as max pressure with my setup, running on 99 pump (yes Shell has blessed us swedes!)

 

BL T67 kit

BL fuelkit with 1000cc

Fcon V pro

uprated plugs, but no DLI

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Impossible to say, depends on too many factors, just map it carefully and keep upping the boost watching EGT's and for det. Then drop it down a bit to allow for climate and fuel changes. IMO mapping on anything other than an engine dyno is risky, if you want to control everything properly, and get the last bit out of it.

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hmmm why is that then chris? my friend got his old car mapped out on the open road, wouldnt this be better as its more "real life" condition more so than a simulator?

 

In a word, no. The best way is on a dyno, you set the dyno to hold a particuar rpm, which it does regardless of the engine load by varying the resistance. Then you go through the different loads and throttle openings and set the fuelling and ignition to produce the most torque safely at that rpm. Then you progress to the next rpm point. It's called steady-state tuning. You can't do that on the road properly as you can't hold a particular point steady, so it's much harder. Once you've got it set up on the dyno you then do things like the acceleration enrichment, overrun etc on the road.

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Significantly more, which is why the blanket statement banded around by people of "no more than 1.4bar on pump fuel" seems very odd to me.

 

It depends on turbo, cams, static comp ratio, cam timing, gasket thickness, deck height, squish, piston cooling, coatings, fuelling, ign timing and spark energy, intercooling, manifold and turbine housing sizing, water injection.....to mention just a few things.

 

It's not the extra pressure rise (say 35psi max) over the combustion pressure but the related issues of all the extra airflow being pumped through the motor that is the issue.

 

Someone may be able to run 1.6bar all day long on Optimax, someone else running a different setup and even a LOWER compression ratio (if other things are not correct) may det at anything over 1.2bar. It all depends on the individual setup.

 

My 0.02p worth.

 

Choose a skilled mapper who you trust! :)

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Ian C runs a good 600bhp on his stock internals (not cams though) and has done 000's of miles on that setup to date

 

Stock bottom end is by no means ideal for max reliability or performance but with careful conservative mapping you should be ok on pump fuel power outputs in a road car.

 

Take things steady on the rolling road and see how she goes as you gradually increase the boost pressure. Sensible steady mapping and a safe tune is a large part of the battle

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The stock pistons aren't forged and in high boost/power/heat applications will deform (more than a good forged piston would) producing excessive blowby.

 

The stock pistons are very good but they are not forged although they are much better than a regular cast piston.

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Just how long do you think the stock items can hold 1000hp then ?

 

 

A ticking time bomb comes to my mind.

 

i wasn´t saying that they would hold for ever. Just pointing out that the pistons are not the weak link. Chris made it sound like the stock pistons are weak, and they are far from being weak

 

the weak link in the stock supra engine are the rod bolts

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To answear your inital question. The stock headgasket is used in many high powered supras over 1000rwhp and is very strong. But i think tuning would be your main concern, even the strongest most expensive things you can buy can get destroyed soon if the tuning is bad

 

here is some more info on the stock pistons so nobody gets the mistake that they are somehow weak

 

Taken from this thread

http://www.supraforums.com/forum/showthread.php?t=337578

 

Batlground went 8's on the stock pistons.

 

Quote from Sound-Performance guys

The stock pistons are VERY good..... I dont know many people that have broken one from power.... only from running lean or detonation.

 

Quote from Silver Bullet

Have had stock pistons...for 5 years now ranging from 700-900rwhp...and been down track a million times. Stock pistons are very durable and i dont see a problem of another 100rwhp all the time. The way i see it....if something goes wrong to melt a piston/motor...no matter what you got in there it will get hurt. But my stock ones will soon have 1000rwhp on them.

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To answear your inital question. The stock headgasket is used in many high powered supras over 1000rwhp and is very strong. But i think tuning would be your main concern, even the strongest most expensive things you can buy can get destroyed soon if the tuning is bad

 

here is some more info on the stock pistons so nobody gets the mistake that they are somehow weak

 

Taken from this thread

http://www.supraforums.com/forum/showthread.php?t=337578

 

Batlground went 8's on the stock pistons.

 

Quote from Sound-Performance guys

The stock pistons are VERY good..... I dont know many people that have broken one from power.... only from running lean or detonation.

 

Quote from Silver Bullet

Have had stock pistons...for 5 years now ranging from 700-900rwhp...and been down track a million times. Stock pistons are very durable and i dont see a problem of another 100rwhp all the time. The way i see it....if something goes wrong to melt a piston/motor...no matter what you got in there it will get hurt. But my stock ones will soon have 1000rwhp on them.

 

Doyou REALLY believe these 1000 RWHP claims?? :) That aside, it's trivial to make an engine last for 10 seconds on a drag strip, but I was taliking proper engine usage on a race track :)

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