stroked small blocks in the race cars?

[eschaider]

Originally Posted by 1795

Just read an informative article on camshaft design.

https://elgincams.com/wp-content/upl...Dema_Elgin.pdf

Have you guys heard of him previously?

Jim

Elgin goes back to the earliest days of hot ridding.

Ed

[blykins]

Originally Posted by eschaider

Elgin goes back to the earliest days of hot ridding.

Ed

Yep, and a lot has changed since then too, although the mathematics are still generally the same.

I like at the end how it talks about how "lofting the valve" is bad. If it weren't for lofting the valve, most NHRA stock eliminator guys wouldn't be competitive.

[1795]

There was a real nice discussion on his webpage elgincams.com in which he further discusses the nuances of cam design and use in an internal combustion engine, I was not able to copy the link. He compares valve overlap in race engines as opposed to street engines and how long duration of overlap may be fine in one and not the other. There is also an nice discussion about the effect of too much overlap on exhaust gases and how they may replace some of the fuel mixture and also have a detrimental effect on heat dissipation.

I was a little confused at first because there is Elgin Industries which Dema Elgin started and then sold to it's employees, which tends to make budget cams from what I have read. Then there is Elgin Cams, which is the new business that he started focusing more on custom and race cams from what I read.

Jim

[cycleguy55]

Originally Posted by 1795

There was a real nice discussion on his webpage elgincams.com in which he further discusses the nuances of cam design and use in an internal combustion engine, I was not able to copy the link. He compares valve overlap in race engines as opposed to street engines and how long duration of overlap may be fine in one and not the other. There is also an nice discussion about the effect of too much overlap on exhaust gases and how they may replace some of the fuel mixture and also have a detrimental effect on heat dissipation.

I was a little confused at first because there is Elgin Industries which Dema Elgin started and then sold to it's employees, which tends to make budget cams from what I have read. Then there is Elgin Cams, which is the new business that he started focusing more on custom and race cams from what I read.

Jim

This article? https://elgincams.com/camshafts/

[1795]

Brian,

That is it! Thanks. The guy does seem to know his stuff.

Jim

[Gaz64]

Originally Posted by cycleguy55

This article? https://elgincams.com/camshafts/

Yes, a nice article.

I don't see any mention of 17 arc versus 3 arc.

Gary

[1795]

I am just going to test the waters with the first scenario. I am guessing the second cam is going to make more power, it's a large engine so maybe in the 15-20 HP range because the intake is opening a little sooner to let more fuel in and the exhaust is closing just prior to TDC. It's a tough one to figure without knowing a lot of other information, but given what we have that would be my guess. This situation may produce more vacuum to suck the next flow of fuel mixture into the cylinder.

Jim

[1795]

Originally Posted by Gaz64

Yes, a nice article.

I don't see any mention of 17 arc versus 3 arc.

Gary

Ok Gary,

Educate the uneducated; what is 17 arc versus 3 arc?

Jim

[Gaz64]

Originally Posted by 1795

Ok Gary,

Educate the uneducated; what is 17 arc versus 3 arc?

Jim

Now I need to find where I read about this.

[1795]

Originally Posted by blykins

Yep, and a lot has changed since then too, although the mathematics are still generally the same.

I like at the end how it talks about how "lofting the valve" is bad. If it weren't for lofting the valve, most NHRA stock eliminator guys wouldn't be competitive.

Brent,

Do you think that he is referring to potential damage to the valve train via valve loft, or potential power loss? If his complaint is due to potential damage to the valve train, that does on the short term provide an increase in power, I can see why NHRA racers would go with that trade off. The engine is rebuilt more often and the damaged parts are then replaced, as opposed to a street performance car in which the person hopes to not have to build the engine.

Jim

[blykins]

Not sure on that one. It certainly makes more power when it's "engineered loft". On a stock eliminator, you're limited to factory valve lifts. Some of those back in the 60's were .450-.490". You can open the valve a lot further than that with some carefully designed parts, but when measured at inspection, it looks stock.

[blykins]

The thing about camshafts is that cam companies spit them out and most guys are happy with them because they have never tried anything else.

I've been testing and dyno'ing camshafts in Fords for quite a while, back-to-back, many times doing cam swaps the same day on the dyno.

Here's a couple of scenarios, tell me how much hp you think is different between the two camshafts, given that all other engine specs are exactly the same:

Scenario 1, 445 ci Ford FE:

Camshaft 1: 286/294, 231/239 @ .050", 114 LSA, 108 ICL, .630"

Camshaft 2: 286/290, 231/235 @ .050", 113 LSA, 108 ICL, .630"

(If you'll notice, the overlap is exactly the same on these two cams)

Scenario 2, 354 ci Ford Cleveland

Camshaft 1: 289/297, 259/267 @ .050", 108 LSA, 106 ICL, .700"/.660"

Camshaft 2: 287/315, 257/277 @ .050", 112 LSA, 108 ICL, .700"/.700"

(Overlap the same on these two cams as well)

[olddog]

Originally Posted by blykins

The thing about camshafts is that cam companies spit them out and most guys are happy with them because they have never tried anything else.

I've been testing and dyno'ing camshafts in Fords for quite a while, back-to-back, many times doing cam swaps the same day on the dyno.

Here's a couple of scenarios, tell me how much hp you think is different between the two camshafts, given that all other engine specs are exactly the same:

Scenario 1, 445 ci Ford FE:

Camshaft 1: 286/294, 231/239 @ .050", 114 LSA, 108 ICL, .630"

Camshaft 2: 286/290, 231/235 @ .050", 113 LSA, 108 ICL, .630"

(If you'll notice, the overlap is exactly the same on these two cams)

Scenario 2, 354 ci Ford Cleveland

Camshaft 1: 289/297, 259/267 @ .050", 108 LSA, 106 ICL, .700"/.660"

Camshaft 2: 287/315, 257/277 @ .050", 112 LSA, 108 ICL, .700"/.700"

(Overlap the same on these two cams as well)

I believe the FE exhaust ports are decent, so I would guess Camshaft 2 gave 25 Hp more. I would have said less but that big of an engine is likely above 500 Hp.

If the Cleveland has the factory 4 V heads with too big on the intake and a constipated exhaust port, then I'm thinking Camshaft 1 will make more Hp because it needs the overlap, but I think it could use more duration on the exhaust. Therefore I'm not certain, as Camshaft 2 may do better. It should give much better low end torque. I only expect 20 Hp difference.

As you said, this is hard to do not knowing what the heads are.

[PDUB]

Originally Posted by olddog

I believe the FE exhaust ports are decent, so I would guess Camshaft 2 gave 25 Hp more. I would have said less but that big of an engine is likely above 500 Hp.

If the Cleveland has the factory 4 V heads with too big on the intake and a constipated exhaust port, then I'm thinking Camshaft 1 will make more Hp because it needs the overlap, but I think it could use more duration on the exhaust. Therefore I'm not certain, as Camshaft 2 may do better. It should give much better low end torque. I only expect 20 Hp difference.

As you said, this is hard to do not knowing what the heads are.

I know less than most of you about this stuff, but this is the way I would have generally guessed, as well... emphasis on guessed! I would not be able to predict a value for the difference, though... no way.

[Anthony]

Originally Posted by blykins

Scenario 1, 445 ci Ford FE:

Camshaft 1: 286/294, 231/239 @ .050", 114 LSA, 108 ICL, .630"

Camshaft 2: 286/290, 231/235 @ .050", 113 LSA, 108 ICL, .630"

(If you'll notice, the overlap is exactly the same on these two cams)

Scenario 2, 354 ci Ford Cleveland

Camshaft 1: 289/297, 259/267 @ .050", 108 LSA, 106 ICL, .700"/.660"

Camshaft 2: 287/315, 257/277 @ .050", 112 LSA, 108 ICL, .700"/.700"

(Overlap the same on these two cams as well)

I don't understand. Looking at the FE cams specs, I would have thought the second cam would need a LSA of 112 to make the overlap identical.

regarding the 351 cams, I would have thought the 2nd cam would need either a LSA of 116 or 112 (depending if took gross lift duration or at .050) to have the same overlap.

[blykins]

Originally Posted by Anthony

I don't understand. Looking at the FE cams specs, I would have thought the second cam would need a LSA of 112 to make the overlap identical.

regarding the 351 cams, I would have thought the 2nd cam would need either a LSA of 116 or 112 (depending if took gross lift duration or at .050) to have the same overlap.

I calculate overlap with advertised durations.

[PDUB]

Originally Posted by blykins

Not sure on that one. It certainly makes more power when it's "engineered loft". On a stock eliminator, you're limited to factory valve lifts. Some of those back in the 60's were .450-.490". You can open the valve a lot further than that with some carefully designed parts, but when measured at inspection, it looks stock.

Very clever!