[chrisjk383]

To all you engine builders…. If a customer asks for a pump gas 1000hp type deal - how do you go about designing such a thing? Do you know of a good chart out there that includes cylinder pressure and IAT and correlates it to an acceptable fuel type? I’ve searched the web and can’t find a good comprehensive chart. Please recommend some literature on the subject

 

[BBF612]

Pump gas you might get away with 1200 or so psi, and max pressure is around 14 degrees ATDC, so you got a good head that only needs around 34 degrees timing to make max HP, so 14 + 34 = 48 x 20 (psi rise per 1 degree) = 960 psi - 1200 = 240 psi cranking compression, but if you have closer to 25 psi per 1 degree crank rotation you start to run into problems real quick, 48 x 25 = 1200 psi - 1200 psi = 0 psi, not much room for cranking compression with pump gas, 108 gas should be good for 1500 psi or so.

Unleaded pump gas burns faster than "race" fuel with that and compression you could get into the 25 to 30 psi per degree pressure rise pretty easy.

BTW....not an engine builder and I know nothing.

 

[Topfun99]

There's no way to figure it out simply based on compression ratio since it's also affected by the rest of the combination - cylinder head material, combustion chamber design and most importantly camshaft. Not to mention the IAT and how the engine is tuned. Even the torque converter stall RPM and rear gear ratio will play a part since that determines how the engine is loaded.

 

[BBF612]

Ya, all that and more. Research other 1000hp pump gas builds of whatever engine and cuin that you will be working with and talk with a couple of cam grinders, ect.

 

[BBF612]

Hardcore Horsepower Aims For A 1,000 Horsepower N/A Street Engine

Mike Petralia of Hardcore Horsepower is aiming big with a 1,000 horsepower goal for a naturally-aspirated 632 big-block Chevy street engine build.

www.enginelabs.com

He needs at least a 1450 carb on this engine, I bet it's running out of "air" on the top end.

 

[BBF612]

On this 598 he's using a 1450 TB.

 

[BBF612]

Choice of cyl. head will make or break the 1000hp deal, 1000hp / 2hp per cfm = 500cfm at max valve lift.

 

[chrisjk383]

Thanks y’all, pointed me the right direction. I’m working with a 560CI BBC with aluminum brodix ported heads and 8.5:1 static CR. Still haven’t selected a cam yet. A/A intercooler procharger at only 10ish psi (with an engine this large it won’t take much to make 1k) so IAT not quite ambient, but also not much higher. I am
Ok with as low as 800 to the flywheel as running shitty pump gas no matter wheee I end up on the road is important to me. More important than a few extra ponies

 

[BBF612]

And that's the rest of the story.

 

[BBF612]

2,600 HP ProCharged 540 cid Big Block Chevy Engine - Engine Builder Magazine

BB&T Racing's ProCharged 540 cid big block Chevy engine

www.enginebuildermag.com

 

[BBF612]

After hours and hours and hours of research I found the prefect cam.....255/262/114/.650., with what you listed at 10lbs of boost you should make at least 1200 hp at 6500 rpm or so.

 

[chrisjk383]

Thanks for the info - I will look into that.. And 6500 idk about that - I'm shooting to make peak HP (800-1k) at 6k with a rev limiter at 6200.. Trying to get some miles out of this build know what im saying??

 

[BBF612]

That's a pretty small cam for a NA 560, so to limit the HP all you have to do is to limit the boost, might be able to make 800 hp with 3 or 4 lbs. of boost.

 

[chrisjk383]

Yea 10 was a worst case value. Most likely will pulley it down a bit. I’d be plenty happy with 850-900 to the flywheel for a street car

 

[surgeline]

Octane isnt the whole story, especially with forced induction. The distillation curve of the fuel is a big deal..