4 cam v push rod

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neilbardsley
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4 cam v push rod

#1 Post by neilbardsley » Mon Apr 15, 2019 8:43 am

Super cool video created by a 2l Carrera 2 owner of him racing and Rennsport. Looks like he has a great battle with a 904. He credits Jacques le Friant with building the engine. I'm quessing this engine is in the 180/200 hp range?

Yet Gregory Campbell passes him like he is standing still! Ok I know that Gregory's car is light and more aero. Greg seems to pass the Carrera 2 on a flat/downhill? However, I seem to remember in an article I read that Greg's engine is a big bore kit so 1720ish?

For the 1720 engine to speed away from a 2l engine on the flat/downhill it has to be making 200+ hp or is the CoA of Greg's car so much better than the Carrera 2?

Regardless thank you to both gentlemen for racing their great cars on a great track!

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Dave Merz
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Re: 4 cam v push rod

#2 Post by Dave Merz » Mon Apr 15, 2019 11:01 am

Definitely a super cool video but for the record that's a 1600 engine in the T5 and not a 2 liter and as such doubtful it's making anywhere close to 180hp. Maybe Jacques will chime in and set the record straight on that one? 904 was piloted by a female driving way over her head and almost took out both cars exiting turn 6 headed up the hill to the corkscrew. Greg's Devin is much lighter than a 356 Carrera Coupe and as such should out handle and be quicker which it was!

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Re: 4 cam v push rod

#3 Post by Jacques Lefriant » Mon Apr 15, 2019 11:29 am

Hi Dave
you are correct the engine was a 692/3 with 40DCM carbs. we could get more hi RPM power with 48IDAs but the driver was not a big fan of taxing the engine. The car was heavy the gear ratios were not optimized and Francisco did not have a lot of experience with the tract but he had a lot of fun. It is interesting to brag about horsepower nos and in competive real racing it is paramount but the real challenge is to weight the reliability/cost and maximize the tuning to get the most from any configuration.
j
 

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Re: 4 cam v push rod

#4 Post by Richard Emerson » Mon Apr 15, 2019 12:05 pm

True When I raced vintage I was asked do I want the 10 hour engine, meaning how highly stressed before rebuild... To be competitive in the top 5 of these groups the engines are so stressed and the power band is so narrow you have to know how to drive, double clutch and heel and toe on descending tighter curves to always make sure you stayed in the power band. With a lighter speedster set up for vintage racing, I would be very surprised that heavier Carrera would be able to keep up. That cork screw turn too requires knowledge and commitment - I remember dropping a wheel off the track the year they installed those deep gravel safety areas for the pro motorcycles races and going up to my axel and having to be towed out post race! Well driven, that 904 should clean up the field. It's hard to make up for light weight - better handling and later braking points in my mind outweigh the performance on the straights and once you can get free to link a few turns you won't be caught.

But as Jacques implies, placing is secondary for most people' the real fun you saw is talking about it post race with your buddies. It's really often you and one or two other cars racing between each other. I remember dueling with Jon Shirley in his birdcage with my Lola for many laps, and then just talking it over with him for an hour afterward.

There will always be that super competitive top 3 drivers, but for most of us it is just plain fun and a successful weekend is to come home safe with hopefully nothing bent or broken. I am glad to see him using a Hans device btw! And that he takes his car out to experience it.

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Re: 4 cam v push rod

#5 Post by C J Murray » Mon Apr 15, 2019 12:50 pm

Interesting subject! First, the driver is always a very important factor. The old truism in racing is that back markers often cheat with big engines but the front runners play by the rules. Those cheaters always justify the cheating by claiming the leaders must be cheating to be so much faster than they are but even cheating doesn't get them up to the leaders.

I don't know what the rules are out west but Greg Campbell's car is a sports racing car, not a production racer. He could probably install any size engine he wanted with any bore and stroke as long as he disclosed that and ran the correct class. Production cars are different. The rules(HSR and SVRA) are clear, stock stroke and 1mm bore increase maximum, period. That works out to 1622cc for a "1600" pushrod. You can not change the stroke even if you stay under 1622cc.

The weight of Gregs car is way less than a T-5 Carrera coupe, maybe 800 pounds lighter. Carrera engines are heavy and that contributes to the difference too.

The 616 pushrod is far more developed than 4-Cam. Work on the Carrera looks to have stopped when the factory stopped using them. Pushrod engines are still being developed for more power and they make a lot of power and do so reliably. Things have changed since the 1960s. A 1622cc 616 race engine makes conservatively 170hp. I don't know what a race 1600 Carrera makes but Jacques does. How much heavier is a Carrera/oil tank than a pushrod? What does it cost to do a rebuild on each?

If I owned a 4-cam race car I would keep the rpm reasonable and enjoy the car for what it is as opposed to how fast it is. The 616 is the right engine for racing hard.
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Re: 4 cam v push rod

#6 Post by C J Murray » Mon Apr 15, 2019 7:53 pm

The Carrera looked to be well driven. I feel bad for the 904, which deserves better.
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Re: 4 cam v push rod

#7 Post by Bruce Smith » Mon Apr 15, 2019 8:28 pm

Thanks for posting this Neil.
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Re: 4 cam v push rod

#8 Post by neilbardsley » Tue Apr 16, 2019 3:12 am

Just wanted to add I didn't wish to imply anyone was cheating.

I like to call a spade a spade but Dave I think you could of made this comment "904 was piloted by a driver way over their head"? I'm not sure that the female part was necessary as the inexperience can be solved by more driving, and training, not a sex change?

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Re: 4 cam v push rod

#9 Post by C J Murray » Tue Apr 16, 2019 7:30 am

I like to call a spade a spade but Dave I think you could of made this comment "904 was piloted by a driver way over their head"? I'm not sure that the female part was necessary as the inexperience can be solved by more driving, and training, not a sex change?
There are so few situations where a woman is not superior to men that men get exuberant and make the mistake of pointing out the situation publicly. Rookie mistake! Think PC. :P
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Re: 4 cam v push rod

#10 Post by neilbardsley » Tue Apr 16, 2019 9:11 am

C J Murray wrote:
Tue Apr 16, 2019 7:30 am
I like to call a spade a spade but Dave I think you could of made this comment "904 was piloted by a driver way over their head"? I'm not sure that the female part was necessary as the inexperience can be solved by more driving, and training, not a sex change?
There are so few situations where a woman is not superior to men that men get exuberant and make the mistake of pointing out the situation publicly. Rookie mistake! Think PC. :P
:)

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Re: 4 cam v push rod

#11 Post by Richard Emerson » Tue Apr 16, 2019 9:14 am

True. Female reference made me wince too. I got beat by Heather Mozart so often in my Elva I became used to it. If I wanted to feel better I’d say her Alfa GTA was lighter, more powerful and had better brakes, but the reality was she was also just a better race care driver too! Really competitive driver in an extremely well prepared car.

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Re: 4 cam v push rod

#12 Post by Mike Ruddy » Tue Apr 16, 2019 3:08 pm

neilbardsley wrote:
Tue Apr 16, 2019 3:12 am
Just wanted to add I didn't wish to imply anyone was cheating.

I like to call a spade a spade but Dave I think you could of made this comment "904 was piloted by a driver way over their head"? I'm not sure that the female part was necessary as the inexperience can be solved by more driving, and training, not a sex change?
An excellent point well made Neil.

Also made me smile.

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Re: 4 cam v push rod

#13 Post by Jacques Lefriant » Wed Apr 17, 2019 1:03 pm

Hi CJ
I respect your comment about being developed this is true about many engines like the Chevy V8 the Type I VW. The Engineering triumph of the Furman engine is that it was developed as an endurance engine with adequate power from it's inception. I congratulate myself when I can achieve the published performance of the engines I have been privileged to service without having to resort to reimaging the engine.
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