How much at the crank did a brand new stock l36 really put out, was it really 390hp?

[Brandon T.]

Just curious, I know with a .30 overbore, fresh valve job etc my l36 barks the tires pretty good going into 4th without getting near redline, so thats stretching it out pretty good but not winding it out or nothing..don't want to pull the engine right back out!

I have no idea what hp it's actually making at the crank or the wheels. It's a m21 with 3.08 so I'm thinking to bark the tires with that combo it is probably 400hp plus at the crank but I have no clue really.

was just curious what they were at the crank and the wheels when new and if barking tires going into 4th was easy to do with a new stock one or does mine have more power than a stocker in the day.

it's stock down to the 7028209 carb so just a fresh rebuild and .30 over.

[Terry B.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

Brandon,

When we did the frame off restoration on my '68 L-36, I had the original engine rebuilt too. I kept most everything stock and decided before the engine left the shop, to have it checked on the dyno. My L-36 produced 412 hp. I'm not sure what that is at the wheels but I've been told that it drops by nearly 20% or more. Others may know better. I have been asked now that it has been all put back in the car to have it dyno'ed again but its too risky for me to take a chance on breaking or blowing up something. I like thinking the car is making 412 hp too.

[Terry D.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

Brandon
Check the archive "Engine Output" or "dyno" this was just covered a few weeks ago. Very good explanation by Duke
Terry

[Dennis S.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

Brandon
Just had my '69 L36 on an engine dyno after a .020 over complete rebuild, including a Comp Cams kit that was the closest to the original (mine was worn on two lobes). The engine reportedly pulled 408 HP and 500 ft lbs on 93 pump gas (with up to 10% ethanol.) Of course, that was with an HEI distributor provided by them, after my rebuilt stock points distributor and crappy coil came up short. The engine has a NORS correct service replacement quadrajet with no jetting changes. I wasn't there for the final pull and don't have the printouts yet, so I can't speak as to the final timing and RPMs.

My guess is they could have made 390 out of the factory, all things being optimal. Many probably would have come up a little short.

[Brandon T.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

wow! I'm very impressed...

I figured ours was putting out a good number because it really runs out great now and IMO to bark the tires as good as it does shifting into 4th with a m21 and 3.08 gears...thats some power!

So, I'm going to assume it actually has around 400hp with everything stock except a .030 over bore.

[Brandon T.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

BTW the reason I asked this question is I watched this video http://www.youtube.com/watch?v=w29VVy0OFUU

says it was unmodified..if so 249 at the wheels is probably around 300hp at the crank which made me ask how much did they really put down..maybe that cars engine wasn't healthy? wasn't sure.

[Duke W.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

Gross HP on a lab dyno? RWHP on a chassis dyno? Correction factor? If so which one, if any?

I discussed these issues in the last couple of weeks along with empirical factors to convert the different ways of measuring horsepower.

You have to compare apples to apples or make the requisite conversions to convert oranges to apples. Otherwise, it's just a bunch on meaningless numbers.

250 SAE corrected RWHP is close to 300 NET, not gross, at the flywheel, and depending on front end accessories and whether or not the fan clutch tightened, this is in the 330-350 standard correction gross horsepower ballpark on a C2/3 with 2.5" exhaust

Duke

[Brandon T.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

I understand they were gross back then and now they're net. Less put it this way is my l36 390hp gross pretty close in actual hp with everything bolted on it as the 95 lt1 I had with 300hp?

these guys that said their rebuilt ones pushed a little over 400hp at the crank is that gross or net?

thanks

[Bill M.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

I understand they were gross back then and now they're net. Less put it this way is my l36 390hp gross pretty close in actual hp with everything bolted on it as the 95 lt1 I had with 300hp?

these guys that said their rebuilt ones pushed a little over 400hp at the crank is that gross or net?

thanks

The 1971 LT-1 was rated 330 SAE gross
The 1972 LT-1 was rated 255 SAE net (basically the same engine)

390 X (255 / 330) = 301 SAE net

[Brandon T.]

Re: How much at the crank did a brand new stock l36 really put out, was it really 390

ok so basically my 390hp 427 has 300 net hp in 100% stock form.

o well it goes pretty good!