My younger brother has a 468" big block chevy in his 71 Nova. Last week, he brought it to the dyno shop where I help out at.

The car is strong, real strong, years ago it ran 10.8's@128-129 with problems. I figure it runs 10.6's@130 mph now.

Anyways, I figure the car to weigh around 3200-3300 lbs race weight, but it only put down 442 rwhp and it was not picking up rwtq down low, but by looking at the dyno sheets, I will guess it made in the 520-530 rwtq area@3000 rpm. His best power was made @ 35 deg and the afr was dead on 13:1.

I thought it would have put down in the upper 400's.

He was rather disappointed after this dyno session...so what does he go and do...hmmm, buy a full ported set of Brodix2-BBxtra to go on his new combo of 572" running @ 14.6:1 compression with a rather large solid roller.

Guess he got bent when I told him my little small block would make power than his big block.

Anyways, I thought it would have put down more...or is that about normal for a big block chevy?

 

If it's an auto, the converter has a hug effect on dyno numbers. I lost ~100rwhp going from a T56 to a TH400 with a 4,200 stall. The car went a bit faster at the track nontheless.

As far as what is typical for a big block, there is not enough detail to even make a guess. Just saying "468 big block" could be a motor making anywhere from 300hp to 1,000+.

Rich

 

Motor is nothing special...

.060" over
10.5:1 compression
Edelbrock Rectangular port heads
2-1/8" headers
Holley Pro Series 950 carb
MSD distributor

Rossler TH400, 3000 stall tq, Dana 60, 4.56 gearing, 31"X18.5" steam rollers, cage.

 

There's going to be at least 20% drivetrain loss in a setup like that. So, that translates to 550-600hp. That sounds about right to me.

Rich

 

I told him just switching over to a lighter rim and a 12" wide Hoosier Quicktime would probably give him 15-20 rwhp just from the rotating mass difference.

He also runs a small mech lift cam.

 

Last year my mid 10 second runs worked out to around 600hp. After the winter projects I'm expecting to be pushing around 850hp now and hope to get into the high 9's. I've never had it on a dyno. I just work out the HP from the MPH on a 1/4 mile pass and correct it for altitude using dyno conversion formulas.

A SBC could make numbers that will keep up with a BBC but it would cost about twice as much or more when the numbers start getting high. For the price of a good 434 SBC that could keep up with my BBC, I could probably build 2 BBC. There are 4 and 6 cyl engines that could keep up with me but I wouldn't want to see what it cost to build or maintain them. No power adders either.

 

One really cannot go by online calcs...my Lightning ran last year 111.3 @ 4750 lbs...yet only put down 414 rwhp.

 

The Nova should be real strong when it's done - can't wait to video that thing. Or the Z for that matter.

 

I don't use online calcs.

Based on your 111.3 and 12.5's run with a 4750 pound truck racing at a 700 foot elevation track, my calculations estimate 480hp from ET and 511 from MPH uncorrected. A supercharged engine may not always give correct numbers because of how it changes the hp from different boost levels through the rpm band.

Stock eliminator cars are not super high HP cars yet all run much quicker than a similar hp street car. It's all about weight transfer and gearing.

 

Not with positive displacement superchargers such as Eaton's, KB's, that make instant boost.

Grunt