425 hp vs. 425 hp

Shaun @ Tru6 · 11-09-2018, 11:23 AM

I'll be doing some restoration work for a '63 Corvette Z06 soon. First, who knew there was such a thing as a '63 Z06. Anyway, pic of 396 motor with 425 hp. Would this motor feel the same as a modern one today with the same horsepower? If they would, how would they be different?

Arizona_928 · 11-09-2018, 11:27 AM

Torque and hp curve.

onewhippedpuppy · 11-09-2018, 11:29 AM

I also had no idea there was a 1963 Z06. I think the SAE HP ratings from the 1960s were actually more than today's DIN measurement, so 425 HP from the 1960s is actually less by today's standards.

asphaltgambler · 11-09-2018, 11:35 AM

^^^^Yes that's correct^^^^^. Good air, open headers, etc on their dyno's. But so did everyone then as horsepower was the selling point. Today the ratings are 'real' where the engine is fitted exactly with whatever emissions equipment it comes with in the vehicle.

BTW: It's a good bet that motor would do the number even with cast iron manifolds.

JackDidley · JackDidley's Garage

Quote:

Originally Posted by onewhippedpuppy

I also had no idea there was a 1963 Z06. I think the SAE HP ratings from the 1960s were actually more than today's DIN measurement, so 425 HP from the 1960s is actually less by today's standards.

True. In 71, I think, they changed the standard for measuring HP resulting in lower numbers.

Pazuzu · 11-09-2018, 11:41 AM

You should convert it to 1980 Corvette specs

nota · 11-09-2018, 11:50 AM

65 for the 396 well fall 64 for 65 model year
in 63 they only had the mystery motor aka the W big block in 427 for nastycar

nota · 11:56 AM

more or less power then the factory ratings is a big debate
trick motors were under rated for drags and ins corpRATS
SOME COMMON MOTORS WERE OVER RATED FOR SALES $$$$$$$$$$$$$$

THE OLD 396/427/454 HAD BOTH AN OVER RATED TRI-POWER AND UNDER RATED 4 BARREL VERSIONS

masraum · 11-09-2018, 12:02 PM

I was aware of the 425HP 396, but I thought it was only a 1965 motor. Before that, I thought it was all the 348/409 motors except for the 427 mystery motor.

As has been stated, the way the HP ratings were done before the early 70s was pretty loose. They would disconnect everything that would sap power and test that way.

I suspect a 425HP 396 from the mid 60s would be very peaky power compared to a much flatter curve from a modern motor with computer controlled fuel and ignition. The old one might feel faster, but the new one would actually be faster. At least, that's my guess/opinion.

masraum · 11-09-2018, 12:04 PM

Quote:

Originally Posted by nota

more or less power then the factory ratings is a big debate
trick motors were under rated for drags and ins corpRATS
SOME COMMON MOTORS WERE OVER RATED FOR SALES $$$$$$$$$$$$$$

THE OLD 396/427/454 HAD BOTH AN OVER RATED TRI-POWER AND UNDER RATED 4 BARREL VERSIONS

Absolutely, several special motors were factory underrated. I've heard that the DZ302 in the Camaros was one of them.

legion · 11-09-2018, 12:26 PM

So there are a number of factors:

1) A '63 was designed to run on leaded gas, and the horsepower numbers reflect that.
2) As stated above, the standards for horsepower were different then, and the numbers would be lower today.
3) Many manufacturers intentionally underrated their engines for lower insurance premiums in the 1960s.

That engine probably won't make 425 hp on unleaded gas.

strupgolf · 11-09-2018, 12:44 PM

In all my Corvette years, I never saw or heard of a 396 in any corvette from 1963. I've heard and seen a z06 in a 62, but it was fuel injected, and suspension based.

BeyGon · 11-09-2018, 12:48 PM

Like others have said, I haven't ever seen anything about a factory1963 396 Z06. Micky Thompson had five of them and they were 327.

Shaun @ Tru6 · 04:24 PM

A quick google yields plenty of info on the '63 Z06.

But I posted the wrong pic (sort of), here's the Z06 stuff I'll be restoring. Also some half shafts.

Apparently this fellow is cut from the same cloth as the Ford restorer I did all the work for the factory supercharged 57 Thunderbird, so that 396 pic is of a restored motor of some other Corvette.

Says he gets points off for over-restored so this will be a challenge. Over-restoring anything is cake. Matching 50s and 60s crappy American surfaces is a challenge. But it looks terribly fun to bring back.

Scott Douglas · Scott Douglas's Garage

That big box injector should be easy to restore. Got a bead blaster?

Jeff Higgins · 11-09-2018, 01:34 PM

I think the most infamous underrating by a factory was the 426 Hemi. 425 hp @ 5,000 rpm. Yeah, okay, that is accurate, but the "problem" (if you can call it that) is that the solid lifter motors would rev to 7,500 willingly. Word has it that not a single Hemi ever left the factory with less than 600 hp.

Imagine trying to insure something like that back then. My uncle Jim did, he bought a '69 Road Runner brand new with the Hemi option. Darn near doubled the price of the car. His regular insurer refused to insure it, so he had to find someone else.

Then one day he had to pick something up on the way home from work, so he drove the family wagon. One of his kids got sick at school, so my aunt Lucy hopped in the Road Runner to go pick him up. Well, they had a really steep driveway down to their garage, and she killed it several times trying to back it up and out. Finally revved it, dropped the clutch, shot up the driveway, across the street, and into the neighbor's living room.

Insurance cancelled and uncle Jim sold the car. So, yes, some of these were highly underrated. It all depended on the objective.

Back to the Chebbys - "ZO6", and even more so, "Club Sport" are hallowed monikers in Corvette circles. I was at the track one day when one of the first of the new C6 ZO6's showed up. The guy had put the distinctive three stripes on the front fender, ala early Club Sport. Couple of the other Corvette guys were severely non-plussed with his display. They explained the whole shebang to me. A real "poser" to them, I guess...

masraum · 11-09-2018, 01:41 PM

Quote:

Originally Posted by legion

So there are a number of factors:

1) A '63 was designed to run on leaded gas, and the horsepower numbers reflect that.
2) As stated above, the standards for horsepower were different then, and the numbers would be lower today.
3) Many manufacturers intentionally underrated their engines for lower insurance premiums in the 1960s.

That engine probably won't make 425 hp on unleaded gas.

How did leaded or unleaded affect power? I didn't think it was about octane, but emmissions. I know that when the lead was removed, in heads with softer valve seats that no longer had the lubricating properties of lead, the seats would start to wear. Or are you just saying that back when gas was leaded, you could get higher octane gas?

Tobra · Tobra's Garage

Z06, Corvette checkbook racecar. Write a check, go to the track. I don't think that split window top would give much protection though. Pretty sure it was a small block. 327 with the super duper big valve heads and a lot of cam, probably less than 400 hp, but it came with a 36 gallon gas tank. Workaround for the racing ban from GM. They had the big block a few years later, that thing would be a pig though, all that weight up front.

Totally not this

LakeCleElum · 11-09-2018, 01:43 PM

Jeff.....You have some Colorful Uncles for sure............

legion · 11-09-2018, 01:59 PM

Quote:

Originally Posted by masraum

How did leaded or unleaded affect power? I didn't think it was about octane, but emmissions. I know that when the lead was removed, in heads with softer valve seats that no longer had the lubricating properties of lead, the seats would start to wear. Or are you just saying that back when gas was leaded, you could get higher octane gas?

Yes, unleaded gas is lower octane than leaded gas. It is also less energy dense than leaded gas. (The lead was used to form longer carbon chains.)