How much boost can our engines handle...SAFELY?

[lthlvpr]

Through our quests for more and more power, it goes without saying that it puts added stress on our motors. We all know that these motors don't come cheap, and, quite frankly, there aren't thousands of these cars around putting thousands of miles on the motors every year to truly gather enough data on longer term reliability and longevity.

It seems like most tuners seem are putting the limit on superchargers and turbochargers around 18-19# boost. I know there are some putting 21-23#boost, but I also know there have been a couple engine failures along the way as well. Not certain what caused them, but it is reasonable to think that as you increase boost your margin for error (detonation/fuel, etc) goes down exponentially.

Even in the most recent 0-200 and back again article in Motor Trend, Heffner's turbo GT only put out 18lbs boost. Clearly he could have turned up the boost, but do we know why he didn't?

At any rate, do we know where that threshold is? Is it 18-19# boost? I would have to think that most of us craving more power want to do so without significantly limiting reliability and longevity.
Thoughts?

 

[Empty Pockets]

"Even in the most recent 0-200 and back again article in Motor Trend, Heffner's turbo GT only put out 18lbs boost. Clearly he could have turned up the boost, but do we know why he didn't"


I think that was because he didn't want to use race fuel - yet still get the job done.

 

[tmcphail]

Based on the setup you can get away with 18-19psi TT or TTS wise with 93 Octane as long as the vehicle is calibrated properly.

You can most definitely go beyond that with race gas for sure !!!

 

[dbk]

I'll ask Jamal again, and I can't remember the exact number he told me, but I think he said at stock power the engine was meant to withstand 200 hours of WOT. With every additional 100rwhp I think he said that number was halved? So a 750rwhp car should withstand 50 hours of WOT? Of course, that's not an exact science given the tuning, and I'm going from fuzzy memory of an old conversation, but I think it's reasonable to expect that with each successive 100rwhp your engine life is significantly decreased. Who's ever going to drive for 50 hours at WOT?

 

[dbk]

You can most definitely go beyond that with race gas for sure !!!

+1

 

[paul b]

The drivetrain and physics are probably the biggest limiting factors.

 

[BlackICE]

...I think he said at stock power the engine was meant to withstand 200 hours of WOT. With every additional 100rwhp I think he said that number was halved?

...but I think it's reasonable to expect that with each successive 100rwhp your engine life is significantly decreased...

Then for a 1/4 mile beast you can build an engine with about 1800 HP and it will last about 1 minute. More than enough for few trips down the strip. That sounds about right.

:thumbsup:lol:rofl:lol:thumbsup

 

[tmcphail]

Then for a 1/4 mile beast you can build an engine with about 1800 HP and it will last about 1 minute. More than enough for few trips down the strip. That sounds about right.

:thumbsup:lol:rofl:lol:thumbsup

:cheers

 

[Indy GT]

I'll ask Jamal again, and I can't remember the exact number he told me, but I think he said at stock power the engine was meant to withstand 200 hours of WOT. With every additional 100rwhp I think he said that number was halved? So a 750rwhp car should withstand 50 hours of WOT? Of course, that's not an exact science given the tuning, and I'm going from fuzzy memory of an old conversation, but I think it's reasonable to expect that with each successive 100rwhp your engine life is significantly decreased. Who's ever going to drive for 50 hours at WOT?

Dave, check with Jamal but I believe our MOD5.4 went thru the standard 300 hour Ford durability test to be "certified" for production release. And although a rigorous duty cycle test it is not all conducted at WOT.

Does not answer the question as to how engine durability falls off with increasing boost though. I really do not know but agree with you it will not be linear with boost and will fall significantly. The engines are, however, built "Ford Tough" and as Jason Heffner shared with me in California, their guys looked at the internals wanting to tweak anything they could for more performance. And came away with the thought that Fred's engine guys had already done everything a tuner/racer would do if he could. Pretty good testiment to what Ford gave us in our cars!

 

[Jason Watt]

Then for a 1/4 mile beast you can build an engine with about 1800 HP and it will last about 1 minute. More than enough for few trips down the strip. That sounds about right.

:thumbsup:lol:rofl:lol:thumbsup

Yep - thats right on...:biggrin

 

[Empty Pockets]

One might bear in mind too that, in reality, how much total boost you have on tap really need not matter at all as far as "wear" or "safe" is concerned. That extra boost ON TAP doesn't hurt the engine at all ... unless you have your foot in it a lot. When you're just driving around - there IS NO boost raising cane with anything. The engine is pulling vacuum. So, from a wear standpoint, it's conceiveable that a 24lb engine and a 14lb engine COULD be driven virtually the same number of total miles with darn little diff in wear/safety between the two at all if you think about it.

(Yes. I KNOW! Fat chance of keepin' yur foot out of it! "WHY do you think the extra boost was put there, Pockets! Shuddup, already!")

 

[BlackICE]

Pockets is right on target! His car can safely run 100 psi boost without shortening the engines life even one minute. How does he do it? Only, Pockets knows.

:rofl

 

[Empty Pockets]

Pockets is right on target! His car can safely run 100 psi boost without shortening the engines life even one minute. How does he do it? Only, Pockets knows.

:rofl

I KNEW that was comin'!!! I just KNEW IT! 'Only question I had was WHO would post it! :rofl :cheers :thumbsup

 

[Indy GT]

Ease up on ole Pockets!!!
Cause he is RIGHT!!!!
(now if we can just get him to show up at Las Vegas WITH the car....)

 

[ViperJoe]

Who's ever going to drive for 50 hours at WOT?

I assume that's an accumulative figure? Still a whole lot of WOT no matter how you slice it.

 

[Jones]

I'll ask Jamal again, and I can't remember the exact number he told me, but I think he said at stock power the engine was meant to withstand 200 hours of WOT. With every additional 100rwhp I think he said that number was halved? So a 750rwhp car should withstand 50 hours of WOT? Of course, that's not an exact science given the tuning, and I'm going from fuzzy memory of an old conversation, but I think it's reasonable to expect that with each successive 100rwhp your engine life is significantly decreased. Who's ever going to drive for 50 hours at WOT?

So a stock engine is good for approx 60,000 1/4 mile runs?

 

[STORMCAT]

I think it's understood that the Stock engine set up ie. rods. bearing crank, fuel system is good as is up to 1000 hp on pump gas. Jason also explains that he wants drive-ability and durability.
They are already limiting the boost in the lower gears so why would you want more when you can't use it... And as stated the test required 93 oct. I'm sure there's more power to be had but if you want to keep the stock internals and fuel system and run pump gas I think this is the cats meow...:thumbsup