Re: Actual HP for an L-78
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: old5.0</div><div class="ubbcode-body">I would guess a showroom stock, assembly line built L78 probably made somewhere between 200-220 horse at the wheels in the real world. That said, pulling 375 to the wheels while maintaining a stock look shouldn't be hard in this day and age. </div></div>
I think that's too low...I would guess 250-300 @ the wheels, depending on the tune. Our 427/425hp did 370+ to the wheels rebuilt to as close to the way it would have arrived from the factory as possible...10.2:1 compression, didn't cut the heads/block, original crank/rods/manifolds, etc, etc. This would push our 3750lb Camaro to 106-108 mph depending on the air.

Re: Actual HP for an L-78
 

Roger Huntington was a pretty on the ball guy back then.

Auto journalist Roger Huntington wrote an article about what these engines actually put out, and here is the list. The figures are for gross HP though, I have the list of net HP ratings too.


Engine------------------Advertised----Rated----------True
------------------------HP @ RPM---- Torque@ RPM-- HP @ RPM

Buick 455 Stage 1-------360@5000----510@2800------420@5400
Camaro Z/28 302--------290@5800----290@4200------310@6200
Chevelle 396 L-78-------375@5600----415@3600------400@5600
Corvette 427 L-88-------430@5200----450@4400------480@6400
Mopar 340-4 bbl---------275@5000----340@3200------320@5600
Mopar 440-Magnum------375@4600----480@3200------410@5400
Mopar 440 Six-Pack------390@4700----490@3200------430@5600
Mopar 426 Street Hemi---425@5000----490@4000------470@6000
Mustang Boss 302--------290@5800----290@4300------310@6200
Ford 351-4 bbl Cleveland--300@5400----380@3400------340@5600
Mustang Boss 351--------330@5400----370@4000------360@6000
Mustang 428 Cobra-Jet---335@5200----440@3400------410@5600
Mustang Boss 429--------375@5200----450@3400------420@5600
Oldsmobile 455 W-30-----370@5300----500@3600------440@5600
Oldsmobile 350 W-31-----325@5400----360@3600------350@5800
Pontiac Ram Air 400------366@5100----445@3600------410@5600

Re: Actual HP for an L-78
 

What were the stats for the Chevelle 454 L-S6 from Roger?

Re: Actual HP for an L-78
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chevy454</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: old5.0</div><div class="ubbcode-body">I would guess a showroom stock, assembly line built L78 probably made somewhere between 200-220 horse at the wheels in the real world. That said, pulling 375 to the wheels while maintaining a stock look shouldn't be hard in this day and age. </div></div>
I think that's too low...I would guess 250-300 @ the wheels, depending on the tune. Our 427/425hp did 370+ to the wheels rebuilt to as close to the way it would have arrived from the factory as possible...10.2:1 compression, didn't cut the heads/block, original crank/rods/manifolds, etc, etc. This would push our 3750lb Camaro to 106-108 mph depending on the air. </div></div>

Yeah, I could see something in the 250-260 range. My guess was completely unscientific based on personal observation.

That said, I think these engines are just begging for a custom cam. The square port BBC heads are excellent pieces that still stand up well 40+ years later. I think the power increase an otherwise stock L78 could see with only a modern, custom cam grind would be shocking.

Re: Actual HP for an L-78
 

The cam isn't the problem, ask any cam company (I've talked to no less than 3 about this very subject), the 143 cam is a pretty darn good piece. the problem (imo) is the huge tolerances from the factory...chambers 10cc+ too big, dome 6cc+ too short, deck clearance all of the place, etc, etc. As i said above, we did an L72 as close to factory as we could get it and it came in at 10.2:1...Scott Tiemann tore into an original L72 out of a Berger copo and it was a scant 9.8:1!

Re: Actual HP for an L-78
 

No need to dyno a street car and especially a show car motor. Whats the point? If the dyno on your motor says 475 hp, it does not mean much at a car show or on the street. Waste of time and money IMO.

Re: Actual HP for an L-78
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chevy454</div><div class="ubbcode-body">The cam isn't the problem, ask any cam company (I've talked to no less than 3 about this very subject), the 143 cam is a pretty darn good piece. the problem (imo) is the huge tolerances from the factory...chambers 10cc+ too big, dome 6cc+ too short, deck clearance all of the place, etc, etc. As i said above, we did an L72 as close to factory as we could get it and it came in at 10.2:1...Scott Tiemann tore into an original L72 out of a Berger copo and it was a scant 9.8:1! </div></div>

Oh yeah, I don't doubt that at all. I know some NMRA Factory Stock class racers that have gone through hundreds of factory E7TE castings before finding a matched set with similar flow numbers and chamber volumes in the same neighborhood as the factory specs. But with the cam, I have to think there's power hiding there.

Look at this way. If you call Comp, for example, and order a custom grind, they'll be happy to sell it to you, but it's still based on lobe profiles already in their inventory. They may be willing to tweek the duration here or the lift there, but it isn't a true &quot;custom&quot; grind. It may be an improvement over an OTS cam, but you're still leaving power on the table. And it may genuinely not be much of an improvement over the factory 143 cam. A true, from the ground up custom is a whole different animal.

A little off topic, and I apologize, but I know of a 347 stroker small block Ford with a set of inline valve Canfield heads, stock 20* valve angle, Super Victor intake, Pro Systems prepped Holley, and a true custom cam that's making close to 700 horsepower at the flywheel. And it's only 10.5:1 compression, totally streetable, and makes a ton of torque, despite the big single plane and small displacement. The key to the whole thing is the camshaft.

I dunno, I'd like to see what an otherwise stock 396, or 427, could do with a true custom designed around the entire car.

Re: Actual HP for an L-78
 

------Big thumbs up on the deck height variations, Rob. Theres a reason that so many chevy engines have been decked and it wasnt for higher than stock, as advertised, compression. Racers were just trying to get all the compression they were legally allowed to run. Bob H told me one time that when they checked the deck height on Red Alerts original LS6 engine that it was off substantially. Actually, he gave me a figure, but that #s gone. My old memory just isnt that good.......Bill S

Re: Actual HP for an L-78
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chevy454</div><div class="ubbcode-body">The cam isn't the problem, ask any cam company (I've talked to no less than 3 about this very subject), the 143 cam is a pretty darn good piece. the problem (imo) is the huge tolerances from the factory...chambers 10cc+ too big, dome 6cc+ too short, deck clearance all of the place, etc, etc. As i said above, we did an L72 as close to factory as we could get it and it came in at 10.2:1...Scott Tiemann tore into an original L72 out of a Berger copo and it was a scant 9.8:1! </div></div>

Agreed - had I known how wide the tolerances were back when I was putting my deuce engine together I'd have checked it more closely, I doubt I'm anywhere near 11.0:1 with my TRW's!

Re: Actual HP for an L-78
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: [email protected]</div><div class="ubbcode-body">No need to dyno a street car and especially a show car motor. Whats the point? If the dyno on your motor says 475 hp, it does not mean much at a car show or on the street. Waste of time and money IMO. </div></div>
Quess I'm wasting all my time and money!
Peter