Mr. Beast96Z,

Nice graph, however your comparison has a few issues. First, the difference in the cams is very small. a 224/232, vs 232/224, and a 228/228 would be more interesting. Second, the 230/224 has a smaller lsa...significantly? Is the intake retarded 6 deg?

I think a better way to look at this is to ignore the exhaust (constant in all cams in this graph) and look at the intakes. More intake on the same CL just increased power. Presumably their would have been some loss of dynamic compression at low speed. Probably not enough to notice with 3 deg additional with 8 deg, that would be noticable.

Presuming the change in LSA with the 230 intake came all on the intake, it would have the same dynamic compression as the 224 intake (intake valve closes at the same point). However, it has more overlap, and the intake wouldn't come into its own until the intake flow could overcome that. This is above the 5000rpm torque peak.

You didn't list the lift. Intake is very sensitive to lift. Exhaust less so. If these are .530 lift, a change to 224/224 .59-.6 lift would probably beat all of these curves. And run better.

 

Any reasoning, or you conclude this is true for all applications because of this one dyno?

 

And think about this....If TR's 224 performed better in every application, why in the hell are they still producing the the 230 & 227? Dyno's don't tell all. Also, you might wanna look at more than .05 duration when you classify camshafts.

 

Sure, there are many tests that could be more interesting, but I was trying to make the point that the same cams on the same lobes with the same LSA woul dmake more power in a foward pattern than reverse due to the fact that they are no longer restricted by the low exaust duration. Seeings how all the cams above had the same EVC at BTDC, I don't think the DCR would change very much. The graph was mainly showing how the cams in the same application didn't perform any better with revese split. It looks to me that they were hindered by the exaust, therefore not allowing them to make any more power until 5500 rpm's.

 

I don't think every application is the same. Before you start bashing, go back and look where I have said that applications vary. There could be some poor LS-1 head out there that flows well on the exaust, but sucks on the intake, then you might need a reverse. Until then, I just don't think they are needed. As far as cam production goes, how many of these cams do you think Thunder sells as compared to other vendors with traditional split cams? I'm sure it is over 20 to 1. As fas as the looking past the .050 comments are concerned, I would look past them if I had the lobe chart, but that's thunders buisness and they choose not to show it. All my comments are being based on the cams being ground on the same lobe style, which is all we have to go on.

 

 

Fair enough

 

there are some people that feel no matter what we do we are intake manifold restricted, not intake port limited.

I would like to see a 224/224 vs a 224/230 like thunder did for the reverse that would give us a good idea of what a traditional split would do.

 

TSP seems to be making a pretty good example of what traditional splits will do with their new cams. Also, most Comp cams are traditional split, and since their main product is cams, they may know what they are doing. Unless running open headers, I doubt we have an exhaust tract that flows as well as the intake. The intake tract is shorter and doesn't have to go through a muffler. It also has a greater cross sectional area, unless you have a 4" catback all they way to the tips. There are also more gasses that have to flow through the exhaust, since it contains burned fuel. Not to mention that exhaust gasses take up more volume since they are much hotter than intake air.

 

Wow, I had no idea Thunders lobes were that stout. There almost XE-R's.

 

They may....I'd bet a majority of their OTS cam's were developed before F-body LS1's started bolting on LS6 intake manifolds, Off Road exhaust, Duals, Kooks headers, efficient cylinder heads & exc. But if the "monkey see, monkey do" approach towards cam design is what you prefer.....

There are interesting approaches toward cam design, that counter yours. Many that are on this forum. They offer a good read.

 

How do NAscar engine builders cam engines with restrictor plates?

 

You are right. I guess the 17 cams and 9 sets of heads I've had on my car doesn't qualify me to say I haven't had ANY luck with reverse splits as compared to traditional splits. I'm just an idiot dyno racer who also runs 11.1's at 123mph in my daily driver.

How can you say that your car wouldn't run even faster with a traditional split without trying one? I don't see how ANYONE can give an educated answer without data. I have dyno data on my car with several different setups and a traditional split cam has consistantly made more power than the reverse splits I have ran. How much data do you have?

 

LOL GOMER, you should seek some professional help.

Did you make up your mind as to which one to keep?

 

You guys are talking right past each other. The answer to which split will work is entirely dependant on which heads and combo one is running. Gomer, it is entirely possible that none of YOUR combos wanted the particular reverse cams that you tried.

The same may not be true for someone running stock 98-00 heads and full boltons. As was said, cam choice is both setup and application specific.

 

 

Hmmmm.....

Where have I heard this before????

Ed

 

How's that "reverse split" coming, Ed?

 

The only place I could see a reverse split is on an NA car, with well ported heads and longtubes (no cats). Under those limited circumstances, it may do well. It would be completely useless for (as noted by others) for nitrous or forced niduction. And the reverse split shouldn't be too crazy.

 

But you'll use a 11* exhaust split HotCam ay? What's to big going the other way, if only a tiny reverse grind can be used?

Gotta factor in how much boost you are using, and if you are only using a small shot. If you're setup calls for an intake crutch and you spray a small shot, that doesn't mean you can't use a reverse split anymore.