FE Power Forums
FE Power Forums => Non-FE Discussion Forum => Topic started by: blykins on May 27, 2020, 02:47:54 PM
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This belongs in the non-FE discussion because it happened on a Cleveland build. Stock stroke (aftermarket crank though), factory 4V heads, solid roller camshafts, Strip Dominator intake, 12:1 compression, 1050 Dominator....
Tried two camshafts the same day, within about 2 hours of each other.....
Cam #1:
259/267 @ .050", 289/297 @ .020", .700"/.660" gross lift, 108 LSA, 104 ICL, 77° overlap
Cam #2:
253/271 @ .050", 285/307 @ .020", .687"/.640" gross lift, 110 LSA, 105 ICL, 76° overlap
How much horsepower do you think there was between the two cams with all other variables staying the same, and which one do you think made the most?
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17hp
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From your question, the smaller must have been a surprise, and probably about 12-14 hp difference. Joe-JDC
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If the smaller one works better or even same, I'd wonder about adding some more duration to the exhaust of cam #1 and seeing what it had then.
But I'm with Joe, based on the way the question was asked I'm assuming the small cam was a surprise.
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Same hp, within 1%. 8)
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16-20 Hp curious if the heads are ported
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#1 by 21 HP.
garyv
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Heads were not ported. I'll tell the story behind it all later.
A couple of notes that I wanted to make is that the overlap is within 1° of both cams and the peak hp rpm was within 200 rpm of each other.
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#1 by at least 40hp
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Since unported Cleveland heads are notorious for poor exhaust flow bias compared to the intake flow, the cam with the largest exhaust duration will probably be better in this comparison test. There is horsepower in the exhaust that most folks don't take into consideration when ordering a camshaft to fit a particular head flow. The lift difference and duration will have a small affect, but depending on where the heads sign off, that might not be an issue with this comparison. I still think the smaller camshaft will be better. Joe-JDC
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This actually happened about 3 years ago, but I was thinking of it because I was reconsidering how overlap affects a camshaft.
A custom cam grinder contacted me several years ago to see if I would be interested in getting cams from him. He said he would float me one if I wanted to try it and his cam would make 30 hp over whatever camshaft I had chosen. This particular Cleveland was my own engine and I had some extra time, so I had him grind a camshaft for it and gave him all the specs for the engine, including flow numbers, port volume, and even the specs for my own custom cam that I had ground for it.
Camshaft #1 was my cam. Camshaft #2 was his cam.
What's interesting is that the overlap was only 1° different from cam to cam. However, there was 28 peak hp difference between them and 10 average hp across the entire pull. My camshaft made 615 hp @ 8000 rpm and his cam made 587 @ 7800. The differences between the cams really aren't drastic. The lift is not too different, intake lobe duration is within 6°, LSA is within 2°, but his cam had a huge duration split on it.
On big intake port engines, overlap helps, and I generally have a very specific recipe I use for Tunnel Port heads and Clevelands. But what I was considering was it's obviously not the overlap number itself that plays the role, it's the culmination of the overlap, lobe separation, etc. This helps me in designing other camshafts, such as camshafts for street engines with vacuum requirements, because I can narrow down the amount of overlap to help vacuum, but still play with the other specifications to make horsepower.
FWIW, the 4V heads flowed 312 cfm @ .700" with nothing but a specific valve job and some new Ferrea valves. No port work.
So for the portion that applies to FE's....
I'm getting ready to finish up another TFS headed FE and I was able to build this engine very similar to the 447 that I have in the dyno section. Same cylinder heads, same intake manifold, same rotating assembly, same compression ratio, same everything.....what I am gonna change is the amount of duration split while holding the LSA the same. From what I've seen in the past, specific heads need a good bit of intake/exhaust duration split but a good A/B test is always worthwhile.
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Even David Vizar said that Clevelands like 108 LSA. If I was choosing without reading you last post and just looking at the specs in a catalog, I would have picked the 108 over the 110.
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Only thing that stood out to me was the huge intake/exhaust duration difference.
Looks like one of those Thumper cams...there are limits to that kind of port crutch.
Did you look at the intake after running the second cam?
Would not surprise me to see a bunch of soot in there from reversion.
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Well to be honest, I ran the #2 cam first because I was confident that the #1 cam would make more power....LOL
I've never seen a scenario where an 18° split was necessary.
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Guess I need to study my poker face some more. Got that totally wrong. Interesting. Joe-JDC
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Joe, I don't think you were on the wrong train of thought, there are certainly combinations where you can have too big of a camshaft.
Here's what I've been struggling with and what I've been trying to justify in my head: I'm not really of the mind that the #2 cam was low-powered because it's on a 110, I think it's an accumulation of not enough intake duration (maybe a small increment made a big difference on this engine), too much exhaust duration (extra exhaust duration can make a blow-down event too early, giving away hp), maybe wasn't in a sweet spot for lift.
Obviously a specific overlap number isn't anything that you should shoot for when building an engine, but IMO, it's something that should be "checked" as part of the process. In this case two different camshafts have the same overlap but are almost 30 hp away from each other.
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I am still learning at 74. I have had more camshaft myths debunked in the last 5 years than all my adult life. Working with lobe separation numbers when the EFI first came on the scene with the '86 HO and aftermarket camshafts, I found that many engines respond to high numbers such as 112, 113, 114, all the way to 117 or more. My work with Y Blocks the last 10 years found that most of them would increase horsepower up to 113, but lost at 114. Still learning. Joe-JDC
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I remember when you first did this test, getting that test cam from the company of a former forum member ( ;D). I think the reason that your cam performed better is mostly due to the added intake duration. That 351C 4V port has a huge volume; it is a big, lazy port. More intake duration will mean more time for port velocity to develop before the piston starts coming back up on the compression stroke, and that port velocity will allow better cylinder filling as the intake valve is closing. A smaller, more efficient port won't need that much time to develop velocity, but the big, lazy 351C port does. I'll bet if you added another 5 degrees intake duration to your cam, you'd pick up even more power.
The only thing that doesn't really fit this theory is the Strip Dominator intake, which IIRC does not have the factory 351C 4V port size. So flow velocity through that intake should be good, and should crutch the huge size of the 351C 4V port. I think it's smaller, like a 351C 4V Edelbrock Torker or Weiand tunnel ram. But, maybe that's not as much of an effect as I thought, unless the Strip Dominator was port matched to the heads.
In any case, I think it would be a mistake to use this particular set of data to draw conclusions about the cam needed for the Trick Flow port, which by all accounts is a much more efficient design than the factory 351C 4V port.
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Jay, the Strip Dominator is a 4V port size. I wasn't planning on really applying the same rules of the Cleveland cam to the TFS FE stuff, but I'm mainly interested in the effects of overlap staying constant while other parameters change. I will be testing that and I have the opportunity to do so with an upcoming build. I usually just watch overlap so that it doesn't cause vacuum to go away (for guys with vacuum brakes), but I have also ground cams for guys where they picked up a noticeable amount of ET with the same cam specs as before, but with less overlap. I'm basically thinking out loud with no real direction of thought process.....just slinging information out LOL
Joe, I have a hunch that you were pulling overlap out with the longer LSA's. Just a thought. I too have seen big numbers from some long LSA's.....I recently built a 460ci SBF that used a 115° LSA and it did really well. Some of my pulling truck engines use 119-120° LSA, but the advertised duration is WAY up there as well (like 315/330°), with large overlap values.
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I just picked up a cherry Cleve Torker I. And a few months ago an equally cherry Streetmaster 400. OK manifolds? I have no experience with 335's.
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The Torker is a great manifold, if my testing is any indication. It made over 700 HP on my last dyno mule, on one of my intake adapters. I also run one on my regular street car, which is a 440 HP 428CJ, and despite being a single plane manifold I don't notice any lack of low end torque.
I have zero experience with the Streetmaster 400.
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Thanks, Jay. By "Torker I" in this case I mean the cloverleaf version, which I think came before the square pad version. Both carry the 2760 part number. Not sure if much difference between the two?
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Ah, think I figured out who the cam guy was, that big exhaust split is his MO. May work for all the BBC he builds as they are on the other end of the spectrum as far as the exhaust port to intake port ratios
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You guys are forgetting that Cam #2 had more attitude than Cam #1 ;D
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The strip dominator is an easy 20 better than the torker by my "in the day" back to back track testing. The as cast ports are smaller (slightly) than the head and port matching is a BAD thing to do. I did do one with a plenum volume increase that pushed up the peak power by 1,000 rpm and gave about 10hp more at 7,500.
Randy
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Not according to my testing, Randy. See the thread below, page 11 of the thread has a table with the data about half way down the page. With a 1000 HP Holley carb on the dyno mule, the Torker and the Strip Dominator were essentially identical, and in fact the Torker looked a little better. With an 1150 Dominator carb on a Super Sucker, the Strip Dominator was about 9 peak HP better than the Torker, and up about 5 lb-ft or HP on average. I think the Torker intake is a lot better than people give it credit for...
http://fepower.net/simplemachinesforum/index.php?topic=4760.0
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You guys are forgetting that Cam #2 had more attitude than Cam #1 ;D
Thumper! Sound is worth a perceived 100 HP.
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Yes, presentation is every thing. Performance, second.
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I'm going to have to agree with Randy on the general experience that the Holley 351c 4V "Strip Dominator" is in the proper application going to out-run the Edelbrock #2760 "Torker"; but I do like the Torker any time I might feel the Strip Dominator is perhaps a bit too aggressive, and each have proven to be excellent when applied properly. ;)
Scott.
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Jay ,
I see what you are saying. I was going off of actual drag strip testing in the '70s. I also tested a Ford D1ZX-FA that was machined for an 850 "regular" Holley , not the dominator and modified. The Holley strip dominator produced the lowest ETs and most MPH on both a stick and auto application. Both were mid to low 12 second ( not bad "for the day") bracket cars. IIRC the difference was .15 ET and 2 mph over the Torker. I have to admit that I only saw Torkers being used on the PSE FE adapters being used back then , or a tunnel ram.
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It might also be that the combination of my adapter and the Torker vs. Strip Dominator gives some advantage to the Torker. I have no comparison data on the two manifolds when used on a 351C, so I can't comment on that. But in any case, I have to say that I was pleasantly surprised that the Torker would support 700+ HP on my dyno mule; and after what I'd read, before the actual testing I figured the Strip Dominator would "Dominate" LOL.