Can Am racing

[j-c-c]

it broadened the torque curve just like these on the GTP corvette engines

On Gary Knutson, Engineer/Engine man for Can Am Chaparral & McLaren:
On Staggered Intakes

"At least outwardly in that time frame, the most significant advancement on the big Chevy engines was the iconic "staggered" intakes, towering trumpets of two heights. They have been attributed to Gary, but he wants to clarify this: " I implemented it, but that idea came from a GM engineer named Bill Howell. I won't take credit for that."

Briefly alternating intakes remedied a cast in quirk of the "semi-hemi" pushrod heads. where every second intake port was a little longer then its next door neighbor. Breathing thru conventional equal-lenght trumpets, theses engines generated two distinct peaks separated by a pronounced dip. Visualize an Asian camel with two humps.

Now imagine trying to hold a smooth power slide out of a corner with somebody else's foot working your accelerator.

"It was sort of like having a turbocharger with lag" as Gary puts it. the guys were always complaining how hard it was to drive. Howell talked us into trying these staggered stacks. We tried a lot of combinations. The best was just a smooth torque curve from start to finish.""

From Vintage Motorsport by Pete Lyons May 2018, page 62

[mekilljoydammit]

I have seen some of the guys at vintage races get the order swapped though, oops!

I can't help but love the big block Can Am stuff. Between vintage races and 80s-90s IMSA stuff, seeing stuff like that at Elkhart Lake totally shaped my idea of fast cars.

[Jeff Lee]

At one time in the late 60's, there were 2 Can Am cars in my garage. One Lola, and one McLaren. Both were powered by aluminum "430" inch BBC's putting out around 650 HP. We took the Lola out to the freeway late one evening. Damn thing sure was fast for that era.

I want to hear more about that night!

[pamotorman]

it broadened the torque curve just like these on the GTP corvette engines

On Gary Knutson, Engineer/Engine man for Can Am Chaparral & McLaren:
On Staggered Intakes

"At least outwardly in that time frame, the most significant advancement on the big Chevy engines was the iconic "staggered" intakes, towering trumpets of two heights. They have been attributed to Gary, but he wants to clarify this: " I implemented it, but that idea came from a GM engineer named Bill Howell. I won't take credit for that."

Briefly alternating intakes remedied a cast in quirk of the "semi-hemi" pushrod heads. where every second intake port was a little longer then its next door neighbor. Breathing thru conventional equal-lenght trumpets, theses engines generated two distinct peaks separated by a pronounced dip. Visualize an Asian camel with two humps.

Now imagine trying to hold a smooth power slide out of a corner with somebody else's foot working your accelerator.

"It was sort of like having a turbocharger with lag" as Gary puts it. the guys were always complaining how hard it was to drive. Howell talked us into trying these staggered stacks. We tried a lot of combinations. The best was just a smooth torque curve from start to finish.""

From Vintage Motorsport by Pete Lyons May 2018, page 62

bill was my contact with GM back in the day. he worked for vince piggens in product promotion dept or better know as the race shop.

[englertracing]

Slightly off-topic, but do they use old style spicer joints in drive axles to put all the power to the ground without issues?

From what I’ve seen, yep, with splined shaft.

Personally, I’d rather have a small block car in the 650hp range. Better balanced and when well driven, aren’t far off the big block cars (if not faster than all but the fastest big blocks - even at a horsepower track like Road America).

small blocks can make 1000hp
just about every 410 sprint car is 900hp +-50hp and thats a setup for only 1 gear......

[MadBill]

" I implemented it, but that idea came from a GM engineer named Bill Howell. I won't take credit for that."...

bill was my contact with GM back in the day. he worked for vince piggens in product promotion dept or better know as the race shop.

As you may know, he's still around and still into performance: https://howellefi.com/

[hoffman900]

Slightly off-topic, but do they use old style spicer joints in drive axles to put all the power to the ground without issues?

From what I’ve seen, yep, with splined shaft.

Personally, I’d rather have a small block car in the 650hp range. Better balanced and when well driven, aren’t far off the big block cars (if not faster than all but the fastest big blocks - even at a horsepower track like Road America).

small blocks can make 1000hp
just about every 410 sprint car is 900hp +-50hp and thats a setup for only 1 gear......

I meant within the rule structure

[Turbo231]

how to build a can am engine from GM

Good stuff. I had no idea GM was involved to this level. I worked in NASCAR for a few years and the factories generally just provided parts and let the teams deal with these kind of details.

[Turbo231]

I know Chevy engines dominated early Can Am and there were some Ford teams but I have not seen any Mopar teams. I would have thought the Hemi could have been competitive. Any thoughts on why no one ran a Hemi and what do you think its potential could have been? Chrysler was very competitive in NASCAR so they could do the endurance thing and they had very successful drag racers using mechanical fuel injection. The horsepower should have been there so why no entries?

[mekilljoydammit]

Seems to me that the reason the big block Chevy more or less worked was that there were aluminum blocks to cut down on the weight a bit which is important when there's no minimum weight - I'm coming across reference to the big block Ford G7A being about 400 pounds over that of the McLarens, albeit probably not all from the engine. Boss 429 and 426 Hemi were both iron heads too in period, wasn't it? So all iron V8s vs all aluminum BBC doesn't sound great.

[Turbo231]

Seems to me that the reason the big block Chevy more or less worked was that there were aluminum blocks to cut down on the weight a bit which is important when there's no minimum weight - I'm coming across reference to the big block Ford G7A being about 400 pounds over that of the McLarens, albeit probably not all from the engine. Boss 429 and 426 Hemi were both iron heads too in period, wasn't it? So all iron V8s vs all aluminum BBC doesn't sound great.

Yes, the lack of aluminum parts was probably the biggest reason for no Hemi's in Can Am. With no weight limit on the cars it would have been extremely difficult to compete. I can't believe though no one made an effort to cast some aluminum heads back then. Chrysler was going full-bore in drag racing and aluminum heads could have been a benefit to those guys too.

[pamotorman]

weight is so important GM went to the trouble to come up with a block with no sleeves to save just 8 pounds.

[Stan Weiss]

Wasn't the Chevy Can Am engine an Alum block with sleeves. 4.44" bore, 3.47" stroke, 6.4" rod, 429.8 ci?

Stan

[mekilljoydammit]

The later ones were linerless, in the same process they tried for the Vega later.

[MadBill]

There was at least one 426 Hemi-powered road racer, built in 1964 for A.J. Foyt. https://www.conceptcarz.com/vehicle/z11 ... -mk-i.aspx It was several hundreds of pounds heavier than typical of the era and was hugely unsuccessful. Foyt said it had the weight distribution of a sledgehammer...