If some people want to give some suggestions that would be great. Here is a pic of my Current dyno with my Dyno from the JPR heads and thunder 224 114 cam from last year (Blue) and the AS 5.3 heads with 232/232 .57x 112 cam that I have now (RED). The only other thing that has been changed beside teh heads and cam is the TTS headers and Catted y-pipe changed to Kooks longtube and catted y-pipe. What I am trying to figure out is the JPR heads flowed:
.200-135
.300-196
.400-241
.450-259
.500-271
.550-282
.570-284
Then down hill

The AS heads flow:
.200-148
.300-206
.400-258
.450-277
.500-292
.550-304
.600-312

The power is nearly identical until around 5200RPM and I believe that is because of the bigger cam I am running now. How can this be? Is some other limiting factor involved? Are flow numbers just hype and a camshaft is all you need? I am just trying to figure this stuff out. I have all the bolt-ons, LS6 intake, pulley, lid, filter, Borla catback, Ported TB and stock descreened maf.

 

What is up with your AF on that run? It looks extremly lean untill about 5k?

 

There will be a limiting factor somewhere in the gas flow, you just have to work out where it is.
It's either Intake, heads, cam or exhaust (accepting that the air filter and swept volume remain the same) so if you open up one or two areas and the power stays the same it's likely that the other parameter(s) will be power limiting.
My 2c.
Tom.

 

The A/F is fine, Eastside's meter was slow picking up, it's 12.5 across the board give or take.

I replaced the TTS Long Tubes and Y-pipe with the Kooks longtube and y-pipe, 2 different type of cats. The intake tract can be restricted by what? I checke dthe filter/Lid MAF, and TB. I do have another TB on the way but thats to fix a different issue.

 

IMHO, all heads that are ported by a competent shop will be withing 10rwhp or so of each other. The restrictive intake on these cars is what dictates the power.

 

So in most cases even if the heads flow 10-20cfm less it wont make a difference to most people?

 

That's my opinion.... but you know how much opinions are worth. Save a little on the heads and spend the money on other stuff, that's worked for me. I watched the heads that made 470+rwhp on my car being flowed and they were just barely over 300cfm, but the low and midlift numbers were outrageous. Peak flow numbers are like dyno numbers, they are good for selling parts That's from the mouth of true dyno racer.

 

Peak yes but my new heads flow better through the whole range and there is still no improvement.

 

A motor is an airpump how efficently you move air in and out is how you make power. Your cam can be optimized to work with either stock or ported heads. depending on where the grind you select falls you may not see the delta when switching from stock heads to ported heads. Ported heads are not hype, but the other thing to keep in mind is that dyno numbers and flow numbers like any other measure can be skewed, and in some cases won't tell the full tale. Sometimes you will have a head that flows less, but will make more power than another "better flowing head".

For instance, Here was a very interesting bit of info that I came across. Just like a dyno, even flowbench results can be skewed. I am not going to name the two heads that were tested, as I am not interested in get into a peeing match with shops about their heads or a he said, she said argument. This information is being posted as that, information. Use information like this to educate yourself, and make informed decisions. For the purpose of this test I will refer to the same vendors a Brand X and Brand Y.

In a test of Brand X heads vs Brand Y heads. Brand Y flows as well on the bench (as good as a Brand X), but don't seem to make the same power on the dyno,etc. From discussing it with the head porter, he was mentioning that Brand Y removes material in areas that will show a gain on the flow bench, but will not make anymore power on the dyno. He says they are big in the wrong spots and too small in others.

A set of Brand Y stage 2s 5.3l heads on a car that had all the bolt ons and a TR224 cam. It made 379/370 or so before adding the heads. After the heads, the car did 413/385 after tuning. A week before, Another car had a set of Brand X stage 2 5.3l heads on a car that already had the TR224 cam as well and the IDENTICAL mods as the other Brand Y car (FLPs, LS6 intake, ASP, stock rear/4:10s,etc). Both dynoed the exact same before swapping heads on (the curves practically overlayed one another). This car pulled 443/418 with the Brand Xs!
On the flow bench, the Brand Ys actually flowed better from .100-.550, while Brand X flowed slightly better past this. Same thing on the exhaust side. This just goes to show that a flow bench is an excellent tool, but not something that should be used as the determing factor in how a head will perform when put on a motor. The CC volumes were identical on the two heads, so compression difference wasn't an issue.

 

Gomer what does your car ET/MPH?

 

LOL.. I'd have to take it to the track to find that out.

Last year on its only trip I ran 11.90's on Sumitomo's mph was 122.x.. I'll look for the slip. I do remember the 60ft was 2.26 though.

 

Pretty impressive setup Gomer....

 

Cats make a HUGE difference. The restriction of the cats combined with the intake restriction will mask head porting gains to a certain extent.

Those power gains are quite respectable imo.

 

J-rod I appreciate the info but what I got from your post is that there is NO way to make an informed decision on whose heads to get since there is no real way of knowing how good "your" set is until you bolt them in. Since everything can be skewed (flow numbers, dynoes) the whole thing just seems shady. I am not saying there is something wrong with the AS heads I received, they even offered to look at the car for me to see where the restriction is but this is my 3rd set of heads and not 1 time did I see any big improvement over others. The cam has always made the best improvements in power.

Chris I have thought of the cats being the "barrier" that keeps bringing my power down. I will have to remove them 1 day, It just weird that the TTS cats and these cats having the same restriction.

 

22hp gain isnt that bad and your right the cam probably played a huge roll in your not making any more power till after 5000 rpms, keep in mind in a drag race you'll almost never be under 5000rpms though. Also in my case i didnt make any more hp then stock, sans borla & lid, till after 3800 rpms when I installed my heads/cam pkg. To expand on what jrod was saying thats why some aftermarket head companies use the ls6 intake to graph off of. I would assume this would allow a smoother path to the combustion chamber...just opening up the port isnt the only anwser. Turbulance in a port whether developed on the merge from the intake or whatever is never good.

 

I am happy with the 22hp gain, remember though the other dyno on the graph is with the thunder 224 cam and the lower flowing JPR heads. I still think the 22hp came from the bigger cam and not the heads....that was the point of my post. If you have ported heads and they dont flow so well it doesnt even seem to matter.

 

Before you run off thinking its a head issue. I have seen a set of kooks headers w/ cats loose 2 hp and gain 3ftlbs of tq. compared to a set of slp headers and cats. Take the car to the track and see how it runs compared to how it did with jpr heads on it. plus what was your compresion ratio with the jpr heads?

 

Frosty is correct,Take the cats off and you'll see another 15RW on both HP and TQ.
Run it and dont worry about numbers.

 

Flow numbers are a key indicator, but you can take them as an absolute. Same thing with RWHP dyno numbers. Like I said heads and a cam go together build them as a combo to make max power. Also, if you are going to restrict the exhuast with a cat, expect to loose some power, and you need to cam accordingly.

Its a great oversimplification to say that because you have had an issue with one particular combo that ported heads are a waste, and that all HP gains can be made with a cam only.

Sure, you could make X HP with a cam only over ported heads and a cam, but the cam for unported heads might end up being quite a bit bigger than the cam for a ported head application.

 

wait wait wait. I DONT THINK ITS A HEADS ISSUE! I am just posting my findings and trying to figure out why my car has always been dyno shy. My CR on the heads at that time was around the same that you get with the 5.3's.
Does nobody agree with me that its odd that the car makes the same power down low with a smaller cam and worse flowing heads than it does with higher flowing heads and a bigger cam?