I had my factory LT-1 heads ported and installed Manley valves (2.00 Intake/ 1.57 exhaust) and these are the preliminary flow numbers. How do these numbers look compared to what others are getting out of factory heads? The car is supercharged with 6lbs of boost and will have a cam custom ground to match the heads and rpm operating range (1,800-6,000). We are going to try and work the short side radius a little more on the intake side:

Intake CFM

.100- 65.9
.200- 128.2
.300- 185.7
.400- 228.9
.500- 251.3 (max flow is at .525 lift)
.600- 239.2

Exhaust CFM

.100- 55
.200- 108.9
.300- 155
.400- 180
.500- 186
.600- 190.4


Thanks in advance for the feedback!

 

Those numbers are kinda low from what I've seen. I'm assuming this was on a SF600. Did you flow them at 25" or 28"? What was the bore, and any pipes, etc used?

 

It was done at Chapman Racing in Woods Cross, Utah. I'll find out exactly how they arrived at those numbers. Would elevation be a factor at all, since i'm 4500 ft above sea level?

 

They were flowed at 28" and no pipe was used for the test.

 

Sure. . . we've all seen better, but 251/190 isn't so bad from some stock castings. Stock is somwhere in the 190 - 200 range, so you picked up 50+ cfm on the intake. I've heard of 290, but that requires major massaging and many, many hours on the bench. If anyone proclaims 300+ from stock castings, I call BS. If it makes you feel any better, we've flowed a couple of sets of AFR 190's at 230 - 240 cfm peak intake.

Mike

 

Thanks for the response. My main focus was on the exhaust side since it is under boost (6 lbs). The porting was done by a local friend who did his best to fix someone's previous butcher job (who lowered the port floors). It wasn't his best work because of this, but i'm very pleased with it.

The exhaust ports have not been polished (I have read that the exhaust side should be near a mirror shine); will this significantly aid the flow or would I be wasting my time?

 

My AFR 210's peaked at 218 cfm on the exhaust side with no pipe and a rough, CNC finish. Someone on here got 275 cfm exhaust from AFR's with a pipe.

 

So my next step is to select a camshaft that will be tailored to my application. I contacted Com Cams and they were less than helpful; they didn't event want my head flow numbers. They were pushing a off the shelf cam (07-503-8) as their ideal application. I find it hard to beleive that this is the optimal profile for me.

Here is a rundown on my car:

1997 WS6 T/A
Stock short block (350)
Six speed w/ 3.42 gears
Desired operating range- 1,800-5,800
Vortech S trim (6 lbs of boost)
Hooker cerami-coated Long tubes
Ported intake/ heads and Manley valves (see first post)

Is there a good camshaft calculator out there that will help me make the profile selection I need?

 

At 6 psi, I wouldn't worry a whole bunch about it. Blower grinds look really similar to NA LT1 grinds anyway, and at only 6 psi I doubt there will be any difference. Just don't use a 106 LSA and it'll be fine.

 

Those aren't bad numbers....I'm sure you're going to notice a difference either way and I'm with Mike, if you're going to keep the boost at a relatively low level, you aren't going to see a big difference in the cam you go with.

What cam are you running now? I'd think an off the shelf grind wouldn't be bad, a good N/A or blower specific off the shelf grind would work well.

 

I contacted both Combination Motorsports and Comp Cams for their respective cam recommendations. Each one was significantly different.

Combination Motorsports- 536/555 lift 224/ 236 Dur 114 LSA

Comp Cams- 503/ 510 Lift 224/ 230 Dur 112 LSA

Combination will grind me a cam to my specs for $247, if I can provide the correct profile. Which brings me back to my original cam question, what is the best choice for my application. There has got to be a formula or calculation method somewhere to assist in designing an optimal profile based on the modifications, vehicle, intended usage and operating range.

 

coughGetwithBretcough

Pardon me...I had a little sammich caught up in my throat.

I'm no cam expert so I can't help ya there but I'll be more than happy to lend you a hand putting her in and getting it back together.

 

Thanks Dustin, the quest for knowlege continues......

 

I'm putting that 224/236 cam in my blown 355, it is an XE grind and is designed for forced induction. I had the hotcam, it worked good. I am curious to see how this new cam is going to do. I would pick this one if you are running nitrous or a blower because it has less overlap and the valve events have been tailored towards forced induction. The other cam looks like a NA cam.

Going to use the 26918 Beehive springs along with gm bowtie SA roller rockers and stock size valves. Those beehive springs are supposed to be better than a double spring and will rev higher. I wanted to change to the guide plates and NSA rockers, but Comp Cams said it would be okay with the self aligning design. The question I have is do I need the CC comp r lifters or just reuse the stockers?

Also since I'm pulling the heads off, I may do some additional head work, ie porting, 3 angle valve job, and flow em. I know the installed height was too low (approx 1.73" with +.050" keepers) so I may have the valve spring seats milled down a bit. The recommended installed height is 1.80".

 

both of those will work fine, but id say the 224/236 would be better suited for stock unported heads, where the 224/230 for ported heads. the only problem i see is the 112 lsa.

but if you really want it done right, get a custom cam. call up cam motion in baton rouge lousianna. theve got awesome customer service. ive contacted them in the past regarding turbo cams. i think lloyd elliot and joe overton also makes custom cams so you may want to contact them as well. bunker on this board is using one of their le3 cams.