Question for Jay. Old Car Craft article with low buck 390 (446).

[plovett]

Hey Jay, I've always wondered this, but am just now asking.  I loved your Low Buck 390 article in Car Craft when it came out, and I still think it's a great piece.   

What I wonder is;  what do you think the result would be if you took the "Strip" engine with the more heavily ported heads with bigger valves and bigger headers, and Holley 850, but swapped out the Edelbrock Victor for the Edelbrock RPM inake from the "Street" engine.

That to me, sounds like the ideal combination of all those parts.  Your own intake manifold comparo shows that the Ebok RPM is good up to the 600 hp range.  What do you think?

paulie

[jayb]

Paulie, I've noticed on several different engines that the torque curves for the RPM and the Victor seem to cross about the 4500 RPM point.  So, I would think that the strip engine with the Performer RPM would outperform the Victor results below 4500 RPM, and then fall off a little at the higher engine speeds.  Despite the fact that the Performer RPM can get to 600+ horsepower, I think it would still be down on peak power from the Victor.  But for a street engine, the Performer RPM may well be a better all-around intake.

[plovett]

Thanks Jay.  Any guess how much horsepower the RPM intake would be down from the Victor at peak?  20?

paulie

[Royce]

Back over 10 yrs ago I built a .030 over 428 with Edelbrock heads 240ish solid cam 10:1 compression.. I had a goal of 500 horse. I ran it with a Performer RPM and peak hp was about 485 @6200  I put a Victor on it and it made just a tick over 500.   The ave horsepower and torque was way better for the Performer RPM, but I got my 500hp and made 50 bucks off a Chevy guy who said no way it would make that.

[plovett]

Okay.  I pulled out my copy of The Great FE Intake Comparo.

On the 390 Stroker motor (500hp), the unported Victor made about 492 hp.  The unported RPM made about 493 hp.  Just estimating from the bar graphs.  The port matched Victor made about 505 hp.  The port matched RPM made about 504 hp.

On the 427 Sideoiler motor (575hp), the Victor (4150 Holley) with port match made about 579 hp.  The RPM with port match made about 566 hp.  The Victor (4150 Holley) with port match and internal porting made about 584 hp.  The Victor (Dominator) with port match looks like about 591 hp.

The old Low Buck 390 Stroker engine from the article is roughly in between those two engines in terms of peak hp.

So I'm guessing RPM intake  would be 10-15 hp down at peak on the Low Buck 390?

[scott foxwell]

Forgive the example, but I think it parallels what's being said here. I did a 540 BB Chev years ago. It was a pump gas hyd roller engine, relatively small heads and a well ported Victor Jr intake. It made 770 hp at around 6500 and 690 tq around 5000. While it was really good power, the customer thought that for the street he wanted a little more lower rpm power. We swapped an out-of-the-box Air Gap, same carb, and the results wer interesting. It cost him about 40 hp @ peak, but the engine peaked at the exact same rpm for both tq and hp. I think it gained a few lbs/ft of tq but the interesting thing was, it only lost 12 hp on average. Made gobs more tq below peak and really flattened the tq curve. The Vic Jr would certainly be the winner on the drag strip but the fun factor was definitely in favor of the Air Gap. I thought it was really interesting that the Air Gap peaked at the same rpm's as the Vic Jr. That tells me it had plenty of cross sectional area for the rpm, which I know they do. My guess is the results would be very similar on an FE like the one above.

[jayb]

So I'm guessing RPM intake  would be 10-15 hp down at peak on the Low Buck 390?

I think that's a pretty good guess, Paulie.