Maximum Safe Power On Pump Gas...?

[AutoXRacer]

So what is the maximum safe power one should shoot for when running on pump gas (92 octane)?

I hear 650-660rwhp is a good safe maximum limit.
But I see plenty of cars running 700rwhp.

I understand it all depends on compression ratio, timing, boost, and heat.
What are you running?

 

[JeremyH]

Many many many factors here. I would start with what your tuner feels safe going to. My threshold for pain on my setup would be around 750-800rwhp on pump 93. But its apples to oranges.

 

[AutoXRacer]

My engine builder has a rule to street tune for a max of 650 rwhp due to the inconsistency of pump gas.
Now if out was race fuel our even E85, then 700 or more could be had.

I agree its not worth risking an engine just to claim 50hp more. But I see quite a few claiming 700+ on pump gas.

 

[JeremyH]

700-800rwhp on pump gas has become pretty common over the past 10 years.

I wouldnt trust a pd or twin screw blower at those levels though mainly due to iat's you will run a higher risk of having detonation.

 

[AutoXRacer]

700-800rwhp on pump gas has become pretty common over the past 10 years.

I wouldnt trust a pd or twin screw blower at those levels though mainly due to iat's you will run a higher risk of having detonation.

So its due to the nature of the FI system/design that limits "safe" power due to IATs?
If I was using turbos or a centrifugal blower, then it would be "safer"...?

How does Shelby do it? Is it in part due to the increased displacement of the 5.4L and 5.8L?
How come they can produce street cars in the 800HP, 1000HP, and 1500HP?

 

[Riptide]

I personally wouldn't go any higher than 14psi on 93 pump fuel assuming stock compression.

Some people have gotten away with going for more. YMMV.

 

[AutoXRacer]

Damn, I'm at 9.8:1 CR with currently 16-17 PSI; peaks at 19-20 at 7K rpm.
Still tuning though...tuner wants to lower the boost.

 

[BruceH]

Jeremy can get away with more because his turbo isn't taking away horsepower.

Your setup would be fairly simple imo. I wouldn't go for more than 18psi or 17 degrees of spark. Fairly safe and it makes what it makes.

Switch to E85 and add all the spark you want but I wouldn't go over 22psi without oringed heads. That's me though. Lots of people take it farther. Lots of people blow motors too.

I understand wanting more power but it's almost counter productive past a certain point on a street car.

Edit: Go with what your tuner is suggesting, he has alot of experience and wouldn't offer that advice unless is was solid.

 

[JeremyH]

So its due to the nature of the FI system/design that limits "safe" power due to IATs?
If I was using turbos or a centrifugal blower, then it would be "safer"...?

How does Shelby do it? Is it in part due to the increased displacement of the 5.4L and 5.8L?
How come they can produce street cars in the 800HP, 1000HP, and 1500HP?

This is just one factor like mentioned. The cooler the iat's are the more power you can make with less chance of detonation. From an oem standpoint the engine is completely deisigned to it with factory wideband 02's, knock sensor to pull timing, compression, tune, tolerances, gaps, yadda yadda.

 

[one eyed willy]

600 is about the most ill ever run on the street. That's about 12psi, 16 degrees timing on pump gas for me.

At the track I plan to run race gas and may go to 18psi.

I'm done building engines for this car....this one pops I'm parting it out and buying a GT 500

 

[05stroker]

My street tune is at 688 rwhp and 16 deg with 9.0:1 compression and 16-18 psi at peaks with the WG on 93 oct.

My race tune runs 23 deg and 20 psi on c16.

It really depends on the setup and tuner. I would say it all depends on your A/F and tune. IMO

 

[Riptide]

OP

I highly suggest you have a read here:

http://www.s197forum.com/forum/showthread.php?t=20639&highlight=fuck+car

 

[warpig12354]

OP

I highly suggest you have a read here:

http://www.s197forum.com/forum/showthread.php?t=20639&highlight=fuck+car

Threads like this are a real buzz kill.

 

[AutoXRacer]

OP

I highly suggest you have a read here:

http://www.s197forum.com/forum/showthread.php?t=20639&highlight=fuck+car

Damn, after reading this 20 page thread...all I want to do now is part my car!!!!

I did not just spend $40K to limit a 1000HP motor to 500rwhp. Thats just retarded. And I don't have race fuel readily available unless I want to pay a fuel truck to follow me everywhere I go.

Fact is many builders like Shelby are running 700HP, 800HP, even 1000HP on pump gas. Yeah, they use bigger displacement engines, but they are still boosting to 17-20 PSI.

I don't know what to think now. If I would have known the limitations of running pump gas, then I would have never built it. Whats the point??

I spent $40K for an approx 700rwhp street car that I can take on road trips, drag strip, and drive to work without worrying its going to blow up.

Sigh... This thread totally depressed me now... I don't even want to deal with my car now.

 

[one eyed willy]

Here, maybe this will cheer you up!

http://www.s197forum.com/forum/showthread.php?t=96792

 

[warpig12354]

What about e85?

 

[warpig12354]

nvm

 

[one eyed willy]

I havnt put race gas in it yet, or even on the dyno for that matter

 

[warpig12354]

Here, maybe this will cheer you up!

http://www.s197forum.com/forum/showthread.php?t=96792

I meant to quote this one, my bad.

 

[BruceH]

Damn, after reading this 20 page thread...all I want to do now is part my car!!!!

I did not just spend $40K to limit a 1000HP motor to 500rwhp. Thats just retarded. And I don't have race fuel readily available unless I want to pay a fuel truck to follow me everywhere I go.

Fact is many builders like Shelby are running 700HP, 800HP, even 1000HP on pump gas. Yeah, they use bigger displacement engines, but they are still boosting to 17-20 PSI.

I don't know what to think now. If I would have known the limitations of running pump gas, then I would have never built it. Whats the point??

I spent $40K for an approx 700rwhp street car that I can take on road trips, drag strip, and drive to work without worrying its going to blow up.

Sigh... This thread totally depressed me now... I don't even want to deal with my car now.

E85 is about 1 mile west of exit 206 at Smokey Point. Fill up a couple of cans at the same time. That would be 26 gallons per trip. You should average about 13-16mpg with your setup.