I have been working on a set of Lightning PI heads and we flowed them today on a SuperFlow SF-600 at 28" H2O.
The heads were hand ported by a local guy. We put larger SS Ferra valves in the intake and exhaust. The intake has a very nice 5 angle valve job and the exhaust has a 3 angle valve job for durability.

Flow numbers are as follows:

Lift Intake(CFM) Exhaust9CFM)
100 60.1 60.3
200 101.5 100.4
300 143.8 134.5
400 179.2 155.8
500 206.9 178.2
600 219.7 191.3


How do these numbers compare with others??

 

Thats slightly better than stock. I had REM do a set of heads for me and they flowed around 237cfm intake and 210cfm exhaust. I dont have the chart with me right now for a whole break down. But these heads and crower cams should rock

My mistake on the number's. Looked at the sheets wrong:o

 

Man I do not see how you can get 280 on the intake or 230-240 on the exhaust without a larger valve and there is not any more room for larger valves??

 

Wow, those are some great numbers. I've got a set from REM with 1mm over SS valves. They flowed

Intake Exhaust Lift

188 163 .300
233 192 .400
235 204 .500
236 210 .600

 

Nathan, did you ever get your motor problem resolved?

 

Collins8

Here's what my heads flowed right off the truck.

Intake Exhaust
.100 54.2 50.5
.200 103.4 103.8
.300 143.4 126.1
.400 162.0 138.0
.500 172.4 143.2
.550 175.5 144.7

John only flowed the heads to .550 cause I stayed with stock cams. I will list the flow numbers after the port job below but will say that the heads are back in the shop now and I gave him intructions to "Pull out all the stops" so to speak. But I don't expect the flow to go up dramatically.

.100 55.0 53.5
.200 100.4 96.8
.300 139.5 133.0
.400 168.0 166.5
.500 196.5 177.4
.550 208.5 180.5

John spent alot of time learning about these heads but stayed somewhat conservative. This time around we cut up a PI head and got inside so we could see how far it can be pushed.

From what I can see, I'd say you got a nice set of heads there. The guys that are CNC porting might be seeing more flow, but I'm about half tempted to buy a set and put them on Johns bench just to see how much BS is floating around out there.

As you can see, the low lift numbers are difficult to come by. John worked his *** off trying to at least preserve the low lift numbers that were there stock.
Hope this helps
Dale

 

Dale,

Your numbers are right in line with what we are seeing.
I really do not expect to see any gains on the truck.
We were aggressive with the port work but the head is not designed to flow much more. We might have got a little more flow out of the exhaust but I wanted to stick with a 3 angle valve job on the exhaust due to the metal getting very thin on the 5 angle. After helping do these heads I have to believe there is allot of inflated numbers being thrown around out there.

Rob

 

Collins8,

That couldn't happen around here. Remember you read it on the internet so it has to be true.

 

Try and find a place that can CNC your heads. I've seen heads that go up 25cfm from a good hand job.........Hand port job

 

Almost slipped there!

 

I had larger intake valves put in.

 

The only thing a CNC does for you is makes very short work of the port job (its fast) and it is very consistant from port to port.
It all starts with a hand port job, so to speak. Thats were the CNC programs come from..... a digitized model or port mold from a hand ground port. Dale

 

You hit on the key word "consistant". It's also more precise too.
If it is a single cyl engine you may be able to get a equal job with hand porting otherwise CNC jobs are better.

More consistant from chamber to chamber = equal burning in each cyl
More precise = more cfm (can/should as long as the place is good)

 

Here are my numbers -

LIFT INT EXH
.050 - 30 33
.100 - 61 57
.150 - 86 77
.200 - 111 96
.250 - 135 114
.300 - 153 130
.350 - 171 149
.400 - 186 164
.450 - 200 174
.500 - 212 180
.550 - 218 184
.600 - 222 190

-Dale

 

Nathan,

Your numbers are correct. Notice the amount of flow you are getting in the 300 to 400 lift area. This is the ramp up area of the cam, and very important to HP production from a flow stand point.

A lot of people like to look at the 500 or 600 #s and make a comparison, but the greatest amount of time and work of the engine is, certainly, not at peak lift but before that where the engine spends alot more time working.

Our heads are flowing, @400 lift, 233.44 on the intake side, and 192.70 on the exhaust side. @600 lift, the #s are only slightly better. 236.11 and 210.20.

A lot of flow in that mid lift range for great power.

Example: Say our motors make peak power at 5200 rpm. Having a high peak number is impressive, but what is more important, are the power numbers that are made in the midrange area below that, where the motor spends most of it time running.