Pitch Black Z

The info from these graphs can be found from the magazine, I just made the effort to input the information in excel to get it into graphical form instead of tabulated.

What you all have been waiting for, the power curves. The graph below shows the power curves of the Stock LS1, AFR with stock cam and AFR with "224" cam. The lower graphs are the difference in power between the LS1 vs AFR and LS1 vs AFR w "224" cam.



Same as above but with the torque graphs



This is the Intake flow including a graph of the difference in flow between the LS1 and 205 AFR Head.



This is the Exhaust flow including the difference between the LS1 and AFR head




Difference in power between the AFR and LS1 head, tabulated form
Power
RPM..........LS1..........AFR......AFR w 224.....LS1-AFR...LS1 -AFR 224
3.0............214..........217......... ..229...........3................15
3.5............257..........262......... ..274...........5................17
4.0............307..........323......... ..330...........16..............23
4.5............361..........375......... ..381...........14..............20
5.0............401..........427......... ..447...........26..............46
5.5............415..........451......... ..486...........36..............71
5.8............421..........455......... ..499...........34..............78
5.9............420..........458......... ..502...........38..............82
6.0............415..........457......... ..505...........42..............90
6.5............393..........451......... ..507...........58..............114

Torque
RPM...........LS1...........AFR....AFR w 224..LS1-AFR.....LS1 -AFR 224
3.0............375..........379......... ..401...........4.............26
3.5............385..........392......... ..411...........7.............26
4.0............403..........424......... ..433...........21...........30
4.5............421..........437......... ..441...........16...........20
4.8............426..........452......... ..462...........26...........36
5.0............421..........448......... ..469...........27...........48
5.5............396..........430......... ..464...........34...........68
6.0............363..........400......... ..442...........37...........79
6.5............317..........364......... ..410...........47...........93


The numbers should speak for themselves.

A little more tech info on the differences between the heads.

Vital Specs..................LS1......AFR
Intake Port Volume......201......205
Intake Valve Size..........2"......2.02"
Exhaust Valve Size......1.6"....1.55"
Chamber Volume........67cc.....66cc

I think these do the heads a little more justice

Edit: Thank you Jake for hosting!




[Modified by Pitch Black Z, 11:55 PM 5/13/2004]

Bink

Thanks for the comp.

Darkness

These look nice, but I'd like to see it compared to LS6 heads cause thats what every one is using for better performance.

marco383

Excellent, understandable technical analysis. However, as has been said many times over, the bottom line on these heads is how much better they perform than the best, ported LS1/LS6 heads people are currently running. The base LS1 head is very old news, and not a particularly challenging baseline to use for flow, torque, and power comparisons. A more relevant test would be how they would fare against modified GM heads from a shop like Cartek that are available for around the same price.

J-Rod

Look at the flow numbers vs port size. Most of the good flowing heads are in the 230CC intake port size range. Now, look at an out of the box AFR. Around the same flow, with a 205CC intake port. That means velocity.

Velocity means power...

NEPTUNEBILL

I noticed in the article that the ls1 heads were quoted as having 1.6 exhaust valves where I though they come with 1.57--and the AFR heads come with 1.55--I talked to one of the members not long ago who had 2.1 intake and 1.57 exhaust valves on his stroker and it made good power is there something to capping off the exhaust flow or limiting it or is this because our heads don't have the potential we need and this is the best compromise for power--

marco383

While I can't dispute the theory, I'd still like to see the graphs of the AFR 205 vs. ported LS6s on the same engine, same dyno, same sheet. This would provide a clear comparison of what are the current, likely alternative heads for a built, stock displacement motor.

Fast81

Now for a counter-view.
IMO I think the AFR205's are a good upgrade from stock LS1 heads for those of us who want more under the hood but aren't looking for the 11sec club avatars. I like the gains from just the stock cam & AFR heads (ie something an average guy could swap on in a weekend). It also leaves me with the next level of a cam upgrade down the road if I choose without the driveability issues of a bigger cam.

If you want something to compare with the LS6 heads wait for the AFR 225's then fire away. There's your apples-apples.

EuG

No offence, but I think that’s the dumbest thing you can do.
Either do H/C or cam only.
Putting high flowing heads with punny little stock cam is such a waste

allanlaw

What am I missing? If I had a stock LS1 producing 421hp, 426 torque, even if measured at the flywheel, I think I'd leave it alone

washguy

I wont be impressed till I see some ls6 comparisons Wash

Pitch Black Z

This is one post from the other thread, and part of the reason I posted all the info, that needs some clarification.

If you look at the graph the power is peaking at 6.5k RPM where the difference in power between the stock and AFR 224 combo is 114bhp not 85bhp , not only that the power has not peaked at that point I'd say there was probably more power there and the difference would have been more if they had added a few more points past 6.5krpm.

I do agree that these heads do need to be tested against some ported LS6 casting as these are some of the best heads available at the moment but J-Rod pointed out another important fact. If the stock castings are ~200cc's porting them will only increase the runner volume. There have been a few ported castings that have been measured anywhere from 225-230cc's. With all else equal the AFR'S should perform better than any ported stock casting on a stock cube engine.

Another issue I would like to address is the drivetrain power loss. It has been my observation that its typically ~50-60hp for a manual transmission vehicle. This was backed up between what Tony Mamo's car dynoed from the engine to the chassis dyno. I would say that at 507bhp would equate to somewhere around 450-460rwhp, this is what Tony's car did on the rollers with this "similar"(not exact) cam.

There are a lot of "if", "ands" or "buts" but at this point this is the only solid dyno information, next to what Tony posted, and IMO there are going to be some more impressive power to be had with these heads over whats available in the market

I would love to see what these heads would do on a G5X car


[Modified by Pitch Black Z, 12:03 PM 5/14/2004]

Demented

Why? Someone recently reported a 42 hp gain from heads only on a stock system. I'm definately considering a set of Patriot 5.3 litre heads with a set of comp magnum true roller 1.85 rockers. That's 547 lift and 10.9 compression The patriot heads flow 296 CFM@550 which is only 6 CFM lower than the 600ish lift cams. I think a respectable 40ish rearwheel horsepower gain could be seen from a 1200 dollar set of heads + 300 dollar rocker arm package. This would be an easy set up to install, it upgrades for valve train, and leaves the car running like stock.

Pitch Black Z

Do you have the graph of that dyno?

Again pay attention to the runner volume of the heads. How much of that flow is from increase runner volume and how much of it is from improved velocity? It isn't meant as a bash towards any vendors or any manufacterers product, lord knows there is already to much drama on forums, its just some food for thought.

HITMAN99

WRONG! Don't knock it if you haven't tried it. I've had two different heads-only LS1's, & both of them made as much power as a cam-only engine, w/o any emissions, idle, driveability, or mileage issues. On a C5, installing heads is also a lot easier than installing a cam, and much cheaper if you have a performance shop do the work. You also don't need an expensive set of heads, with big aftermarket valves. Stage 1x heads work just fine.

Hardtop01

If you can't run 11's with just the heads, its not AFR's fault. I agree with EUG, if you do the heads, you might as well throw a cam in there too. There are plenty of cams that don't sacrifice anything.

Bruce

mdhmi

I would be very interested to see some real hp #'s and 1/4 mile track ET/MPH's with a heads only setup. I think there are a fair number of people who are willing to swap the heads but not the cam. Swapping the cam can cause emissions issues as well the installation costs are more than doubled.

Mark

Troy Roberts

Moved to C5 Performance Results.

MikeJamesC5

What about the 225 heads and what kick azz cam could I use with them when they come out?

NJVetteGuy

With the right combo, you don't need heads or cam upgrades to run 11s. You don't even need headers if you think a little when choosing your components. The cost factor for heads vs. the performance gain really doesn't make it a good bang for the buck mod. A cam will get you more power per dollar, and if you can R&R cylinder heads on an LS1 you have enough mechanical aptitude to perform a cam swap. The gains from any upgraded cylinder head will be substantial if matched to the right cam for your combo.

Excellent point, perhaps the reason this comparison hasn't been made available is that the gains from the AFRs vs. aftermarket ported LS1/LS6 heads was not much, if anything at all Time will tell as to whether these heads will be the way to go in the future, as I'm not impressed yet