Quote:
Originally Posted by Steve C.
I'm confused as to the final cubic inches involved.... some posts suggest 522 and others 535. What is the stroke and bore ?
If you bring back one or more copies of a dyno sheet it will indicate the peak torque rpm and peak power rpm, and with the TQ/HP numbers to report.
The 535 combination I linked here in my post #10 with the 'same' cam, similar cylinder heads and a Torker II intake with 850 cfm carb made peak torque at 4400 rpm and peak power at a low 5400 rpm. A 1000 rpm spread.
With a Victor intake and 1,150-cfm Dominator carburetor it pushed the peak power to a higher 5800 rpm. A 1400 rpm spread.
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Quote:
Originally Posted by dmac
650-700 hp at above 6500 rpm is one thing, but poster asked for 650-700 at 6000 rpm. Does that combo you listed do that? To me, building for 6000 rpm is an entirely different level that 7000 rpm. Asking for street driveability and pump gas seems to be asking a lot. . On the street, it is going to see a LOT of 2000 rpm to 3000rpm driving. This sounds like a job for a computer controlled engine?!?!?!
I enjoyed driving high compression 13:1 on the street when premium was 110 octane and octane booster was loaded with lead and really worked.
Is there a formula for how many cubic inches you need to get 700hp with 10.5:1 cr at 6000 rpm? Seems like that is the starting point, and you need to work backwards from there. Maybe a turbo, or blower????? May not even need as many cubic inches!!!!
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A true 700hp, on pump, and driven regularly on the street?
Similar to dad's. He made 724 HP at a peak of just 5700 rpm. Peak torque of 764 was down at 4,000 where they started the pulls but the curve was already falling, so we never really found out exactly where it started, but even with that the spread was 1700 rpm, and it stayed over 700 ft lbs. for the entire pull, so it's a very happy engine.
This gets easier with more CI, and a good cylinder head. Which is why he went the direction of more cubic inch building a 571 Pontiac and stayed with the old Edelbrock round port heads he already had (not high ports). Now it doesn't need quite as much camshaft, and the smallish Pontiac conventional heads while hurting HP a bit, will make gobs of torque. He has no need to spin the engine up tight, makes torque everywhere, and cruises just as easy as the more mild engines I have here.
Of course it can be done with smaller CI Pontiac, but it requires a really good cylinder head and generally more camshaft, then drivability starts to become a concern for many, and what is considered a "real" street engine that you can use on a regular basis.
For comparison sake, Many of the crate 540 BBC's offered use the same (small for the engine size) Comp 248/254 camshaft, have 10:1 compression, and come with a dyno sheet, and they make right at 700 HP around 6,000 rpm, but torque is lower in the 670 range. Blueprint sells one just like this with a warranty. But it's a little easier to hit that HP goal with this engine and the small camshaft considering the heads flow nearly 370 cfm on the intake side and have excellent exhaust flow to go with it.
Doesn't have the torque curve the Pontiac will though. Personally I prefer to have a great cylinder head so I don't have to go so crazy on camshaft when I'm looking to hit a certain power goal. Makes for a happy street engine that's a little more on the tame side. Cubic Inch is your friend.
Just depends on how you want to approach it. Most street cars in here will have a hard time harnessing the torque curve a big inch Pontiac will make, or even the Chevrolet example for that matter.