What is the highest boost pressure in BAR that an engine car run?

[Robin Plummer]

I seem to recall that in 1986 the F1 BMW M12/M13 1.5 Inline 4 ran 5.3 bar boost in qualifing. Has there ever been cars that have raced with a boost higher than that in all motorsport?

[avsfan733]

im pretty sure that the top fuel dragstersrun around 79 psi not sure the conversion or how true that number is but from my readings air would be nearly colid at that point....theoretically there is no maximum pressure only what the engine can take

[Sirio]

14.7psi = 1 bar

Cat Race truck runs 4Bar.

I think tractor pulling that the 'God Dam' Yanks do have some very high boost engines.

What does 'nearly colid' mean?

[BrettFrancis]

I think he means "nearly solid", but typed with a speech impediment... or a mouthfull of beverage.

[StuiE]

I remember reading the Sierra race cars ran about 40-50psi in qualifying trim.

[Sirio]

found some info on the tractor pulling boost figures
http://www.pulltown.com/about.htm
4 turbos and over 250psi sounds like fun.
I would imagine that they are running them in series with intercoolers between each stage so they can get the high boost levels without the intake temp being very high.

[avsfan733]

yes i did mean "nearly solid" as opposed to colid, I also meant 70 psi not 79...typing issues last night didn't get noticed.

realize that pressure is also a function of temperature within a set of known and given gas laws so when you hit the intercoolers and start cooling air down you start loosing a lot of pressure even with the high pressures. think about 250 psi with a 10:1 compression ration, suddenly that becomes 2500 psi plus the fuel that gets injected. probably serious problems with detonation because the heat that that would creat must be incredible

pressure * volume / n mols and temp
so the mols and conastant cancel
compressing a gas from 250 psi to 2500 psi with a starting temp of 100F (reasonable approximation given the pressure) and a .5 L cylinder and 10:1 compression would create an very high temperature before you even consider the latent heat of the head and block

[imull]

dragster engines nearly go to hydraulic lock apparently...

good point about heat avsfan. surely they must run some seriously high octane stuff to avoid the detonation

[KC]

Top fuel engines run just at hydraulic lock to get as much power as possible. Nitromethane is very slow burn. Enough that ignition timing is usually set at 50 to 60 degrees before top dead center. It can take a huge amount of compression without spontaneous combustion. Imagine an engine using 3.5 liters of fuel per second at wide open throttle. The typical blower setup is to run 30% to 40% overdrive from the speed of the crankshaft. If the spark plug fails to fire, the next fuel-air charge coming in will hydraulicly lock up the cylinder and destroy the engine and explode the blower. By half track the lean burn condition has melted off the end of the spark plug and the engine will continue to run by firing off of the 1400 degree F exhaust valve. Typical engine failures are for a dropped cylinder (does not ignite). Usually costs a conrod and maybe a crankshaft. Blower stalls and the belt flies off which can melt down the pistons from ultra-lean condition. Sometimes a bearing just is not set right and it spins and welds itself to the crankshaft or rod end and wrecks the block. These things operate at the most radical and shortest life of any racign engine.

[avsfan733]

they are certainly incredible I love dragsters just for the engines.

I've read figures of them suckign down 500 crank hp any truth? What kind of pressure is that creating?

[imull]

I read somewhere that the top level dragsters super charger uses more power than a stock hemi produces. whatever a hemi is :confused:

there is a thread somewhere in the archives here about dragster engines...

[Sirio]

All you ever wanted to know about hemis

http://auto.howstuffworks.com/hemi.htm

[KC]

In today's parlance, a Hemi is Chrysler's new V8 units found in their trucks and the new 300M. In drag racing parlance a Hemi is a Chrysler 426cid V8. They revolutionized drag racing during the muscle car wars in the 60s and 70s.

[X-Guy]

With the exceptions of Mickey Thompson's Challenger I and Nolan White's Spirit of Autopower, only Hemi powered cars have clocked over 400 mph with automotive engines. The Summers brothers Goldenrod, holder of the wheel-driven record for almost 26 years, was powered by four Hemis and remains the only normally aspirated car to clock over 400 mph. The Burkland's Montana Eagle, currently the fastest piston engine car, is powered by a pair of supercharged Hemis.

[RWC]

Those drag engines really are spectacular!


I heard that they went over 6 bar on occasions with the BMW f1 turbo engine,but the quoted 5.3 bar does sound like a more sane official maximum.I think they peeked at about monza '88 when Fabi(?) set some sort of record of 352kmh before the first chicane (not sure if the details are exactly right)
Now THAT is something that would bring a smile to my face...............

[Robin Plummer]

I dont think it would have been Monza 88 as from 1987 there was a 4.0 bar limit and 1988 2.5 bar so maybe 1986.

[Green Monster]

http://www.bobnorwood.com/Max-4%20Te...%20Summary.htm

What is the highest BAR an engine can run? Ask Bob Norwood.

[avsfan733]

that car was featured in an import magazine not to long ago i can't find the article but i remember it being around 45 psi which is 3.1 BAR
6 BAR is 87 psi
5.3 BAR is 77 psi

[bartman71]

have you seen how long it takes to rebuild a top fuel engine?
i heard the do it between runs in about 1 hr

[Carse]

I think the lancia lc2's at le mans ran large boost on the turbo's as the engine was only a 2 litre i think. They cranked the waste gates shut for ages before it dumped and when it did it spat alot of flames!

Also the 956/962's ran alot of boost in a qualifying session, before the aco imposed regs. (the 936 icxx won in too i think was turbo charged and ran alot of boost as again it was a small engine)

[listernoble]

In the 1950's BRM used a 1500cc V16 which ran 72psi boost from a centrifugal supercharger, similar to that used on the WW2 Merlin Spitfire engine.
The BRM engine produced 600bhp at 12,000rpm.
But it was a bit unreliable.
Lister

[GolddustMini]

but sounded absolutely ****in awesome