General Jack

iTrader: (4)

Most of what I've seen on the AFR 205 heads indicates that they perform best with a traditional split cam with about a 4 degree difference in intake/exhaust duration, i.e. 224/228.

I've also come to understand that reverse split cams work better in stock head applications...

Is any of this true? More importantly, will my 230/227 .591/.571 112 lsa cam work well with the AFRs, or would moving to a traditional split cam of similar specs increase my power noticeably? Its cost down to a cost thing but I really want the AFRs.

I plan on having the heads done this fall but I'm doing the reseach now... Thanks in advance...

PREDATOR-Z

From experience Reverse splits like good exhaust (heads/headers)
The AFR are not too much exhaust oriented. Now this is an observation based on reading here and dyno reports, not real life testing, so I cannot really substantiate this comment.
I have a 224/220 and I opted for PRC 2.5's.

General Jack

iTrader: (4)

When you say "exhaust oriented" do you mean intake v exhaust flow characteristics, valve size, etc.? I understand this is more of an observation but I'm trying to learn. Are the PRCs better suited to a reverse split cam?

Tony Mamo @ AFR

iTrader: (13)

Has anyone actually back to back tested a ported factory casting (or stock for that matter) with a reverse split, and then compared it directly with a traditional foward split on the dyno the very same day?? I'm guessing the answer might be no but would be very curious to hear the results. My contention is that MOST heads will make more power in typical street car with a full exhaust by moving up to a single or forward split cam. Sure the reverse split will idle a little smoother and make a little more power very low in the curve (both due to less overlap), but the reverse split won't make as much peak TQ and will have a greater negative effect higher up the power curve, closer to and past peak HP.

Will the AFR's make a significant impact on power with the cam you already have....you bet. Is that the most optimized cam for the AFR head?....probably not. If your looking for spectacular results and have the money to buy both I would advise you look into something a little different. If you would like, feel free to contact me at AFR and we can discuss a few of your options.

Tony M.
(818)890-0616 Ext. 109

PS....The only head configuration that comes to mind that might have liked a reverse type of grind would be an out of the box LS1 head. Reason being it has approximately an 83-84% Intake/Exhaust ratio....that doesn't mean its good, it simply means the intake is weak compared to the exhaust. Any good ported head will have somewhere in the 75-80% range, with the norm being typically less than 80 percent. Our 205 for instance comes in about 78%, our 225 exactly the same. A lot of people think that a high intake to exhaust ratio automatically means that it must be an excellent cylinder head, while the reality is that once you start cresting over the 80% mark it is usually an indicator that the head simply has a weak intake port compared to it's exhaust (much like a factory LS1 head). By the way, an LS6 head out of the box has about a 74-75% intake exhaust ratio and we all know it makes more power everywhere.

General Jack

iTrader: (4)

Tony, you can bet we will be talking at some point in the not so distant future. Quickly though, are the traditional splits what you would typically recommend with the 205 head? I seem to remember a while back that a 224/228 type grind was paired up with the 205s and it made pretty good numbers. I would probably want to go with something a little bigger than that, maybe around or a bit over 230 intake and exhaust duration, lift under 0.600 on both - and a traditional split if those provide the optimal results.

Thanks for the great info.

Sport Side

iTrader: (6)

Tony, is this with an intake manifold attached? If so, which one? Thanks.

jrp

iTrader: (16)

my guess would be w/o an intake as thats usually the standard the E/I is taken.

FWIW my E/I taken at .400 lift is 65% with a radius and 70% with my ls6 intake.

Sport Side

iTrader: (6)

What I'm thinking is that the 300cfm that the 205 flows will drop down substantually. Right now, it reads 308/240 at .6''. How much cfm would an LS6 intake take away? -30, -40????

So, that 78% turns into something more along the lines of 85%. Depending on whether or not those numbers were taken with some sort of an exhaust in place of course.

Slowhawk

iTrader: (12)

I've tested traditional and reverse split's on AFR 205's in the same car (Cam swap only).Personally I like the reverse split's better so far.The power from 2k to 4k seems to be better for street driving and the idle low speed is smooth.

Personally I want to try a 11.8-1 compression AFR setup with a 220Cam.

Tony Mamo @ AFR

iTrader: (13)

I agree Don....A reverse pattern will have a slightly smoother idle, pull a little more vacuum (assuming the same intake lobe of course), and generally make a little more power in the lower part of the tachometer. I have made mention of that fact in some of my previous posts.

BUT...It will have a negative effect on both peak TQ and a greater negative effect on peak HP. During back to back cam testing on the exact same engine the exact same day, I witnessed a 5-7 peak HP gain going from a 224/220 to a 224/224....and then shortly thereafter found another 5-6 HP moving to a 224/228....ultimately the cam we chose to feature in my C5. I felt the losses in TQ down low were worth the trade off in peak power and how the motor extended it's usuable power band to effectively 7K with a small, very tame Hyd. roller that had good idle manners. I felt it offered the best "have your cake and eat it to scenario" with a caveat of trying to make big power in mild mannered package.

Guys...camshafts are a give and take....while the right cam choice might give you a better "compromise", there is still ALWAYS a compromise. It's all about figuring what you want or need, and picking the cam that best suits those requirements. While some would opt for the slightly smoother idle and slight increase in low end TQ, others would opt for a little more power upstairs. There is no right and wrong....the toughest part is to really figure out what will make you the happiest over the long haul.

Just my .02

Tony M.

No Juice

iTrader: (11)

I was kinda thinking the same thing but some where around 11.3:1 with this cam 220/224 560/578 112. What do ya think?

Don you have pm

Hardtop

iTrader: (3)

Tony, the 224/224 should make more power than the 224/220. A better comparison of traditional and reverse splits would be comparing your 224/228 to the same cam 228/224. Thanks for the info, Tony.

Bruce

schultzsj

iTrader: (1)

I will be running, at least for the forseeable future, stock heads and LS1 intake with LT's. I recently bought a 227/224 from Thunder Racing on their recommendation after thinking that I wanted their 224/224.

When I asked why they recommended a reverse split when almost all cams made for the LS1 are either traditional split or neutral, they said simply that they were able to make more power that way. Since they ought to know, I took their word and will be installing the 227/224 this fall with 918 springs and Ti retainers.

Steve

BUYAMERICAN

I believe all of LG's cams are split duration and split lift. Lou likes the AFR's.

Tony Mamo @ AFR

iTrader: (13)

Hi Bruce...

I wanted to keep the intake lobe no larger than 224 @ .050.

That was a critical part of the "recipe" for me. The later closing point (intake side) of a 228/224 would have slightly detracted from idle quality and (with the shorter 224 exh. lobe) I don't feel it would have made a significant peak power gain, but of course not trying it simply leaves it open to speculation. My car put down 400+ ft/lbs as early as 4000 RPMs and crested 350 as early as 3000. With a solid peak of 435-440 RWTQ and 475-480 RWHP, I feel that cam was very close to optimal given it's idle and driving characteristics but with another 3 days of dyno time who knows what I might have found.... .

Hardtop

iTrader: (3)

I can't argue with the numbers from your setup. It would be an interesting comparison, though.

Bruce

Ed Curtis

Be careful about generalizing about reverse split or traditional split camshaft profiles. If you are in the same "family" of lobes (like Comp's XER) then you can do some comparing but go outside those lobes and watch out! You can get fooled.

Fact is not all "224* at .050" camshaft lobes are the same. There are many fast ramp, slow ramp and a lot of "in between" lobes that can be used in a cam design. You wouldn't believe how many "224* at .050" lobes there are available!

When it comes to what "should be" considered in this cam thread, lobe "area" should not be ignored. It really is a more important factor of the camshaft's design than just that one .050" spec...

For example, my GTO's (relatively) small 229*-230* cam rumbles and makes power like it has a much bigger camshaft in there. Ain't that right Don...

Ed

badpewter-z

iTrader: (4)

Im currently running a reverse split with my afr's drivabilty and midrange are awsome too compared to a cam that had a regular split .

hmmmmmmm i might be interested , ill even buy the cam. if it doesnt work i can always sell it espiccally after seeing what the last few 220 cams have done

Sport Side

iTrader: (6)

I think smaller camshafts are becoming the new fad around here.

jrp

iTrader: (16)

thats because of efficiency with the AFR head. with the right combo's people arent needing as much duration to make the same power as those who have come before us.