Actual HP for an L-78

[old5.0]

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.

[SSRSBOB]

Called my engine builder. They vary, he has done many. Usually in the 415-435 range. Many head and block castings are better than others, core shift, etc. That's why no two L78's make exactly the same power. it's generally a range.

Bob

[XXXGoldL34M20]

just tell everyone that it is <span style="color: #CC0000">425 H/P</span>
my buddy with an L78 1970 Chevelle does and no one ever questions him.

[Chevy454]

<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.

[Keith Tedford]

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

[XXXGoldL34M20]

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

[old5.0]

<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.

[Chevy454]

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!

[Salvatore]

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.

[COPO PETE]

<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