DenzSS

I know this isn't a popular topic, but if anyone can offer advice it would be greatly appreciated.

He has done a pretty good job up to this point, but he is getting stuck at .550 and above lift. He has a flow bench and and is flowing the heads after every small change. He has seen broad gains throughout the .200 - .500 range, but is getting very few gains above that. They are flowing in the high 270cfm range from .500 -.600 lift, but nothing he has done so far is making much of a difference.

The valves are Ferrea 2.02I/1.55E.

Paul J.

I have not been able to get more than mid-high 280's at .550 lift with the stock seats and swirl vane intact. I think it varies from head to head with the short side radius height, or casting tolerances. Don't dwell on peak numbers, port volume, velocity, moderate swirl, and most importantly, flow with the manifold bolted to the head are more important for a street, strip car. Focus on maximizing flow from .200" to .500" especially with the manifold bolted on.

Do you ever see anyone advertise flow figures with the manifold bolted to the head? Aside from ARE, I haven't seen any. The manifold can have a dramatic effect on the overall flow. For example, I flow tested a 5.7L head flowing 278 CFM at .550" lift but with a LS6 manifold bolted up it dropped to 245 CFM.

Concentrate on the short side radius, widen and smooth the radius from the floor to the valve seat. This area will usually saturate at .550 lift and higher, and the flow will actually decrease while the swirl increases dramatically.

Of course, the LS6 intake port is a different animal. It is matched very well to the LS6 intake manifold, loosing very little at peak flow. A 6.0L truck head I am building for my car flowed a max of 288 CFM at .550" lift and only lost 18 CFM with the LS6 intake bolted on. That's 270 CFM! Enough to make 530-550 Flywheel Hp with the right components. The engineers obviously matched these two together very well. I hope I have shed some light on the subject.

Paul J.

H82BBad

area of big flow increse is

Put a head gasket on it and open the are around the bore up a little if you are using larger valves.
Ferrea Valves seem to flow better up top than the others.
Once they have been back cut they will lose flow on top and pick it up on the low lifts.
Good luck
I prefer to leave the swirl vane intact.

Reckless

iTrader: (9)

Paul...was looking at some sponsor heads the other day...they are really opened up on the intake floors (is this the short side?).

They also had the sworl damns all but removed. You could see about an inch of valve guide in there. The ehaust isn't much of a crutch I guess. They were hogged out pretty good though.

I think what you said about volume is correct. It seems the heads I looked at were very volumous (is that a word) on the intake ports. I may try to rework mine this winter.

PAULJ99Z

The name of the game is to get the highest flow from the least amout of port volume. This will increase velocity of the port and help the "ramming" effect of the air - fuel charge fill the chamber as the valve is closing. The result is more power across the RPM range. As far as material removed, take the minimal amount possible off the port roof where the velocity is lowest and concentrate on the floor and short side radius where the velocity is highest. And, In my opinion, flow test the heads with the manifold bolted up, which is just an extension of the port itself.

Paul J.

DenzSS

Well, thats exactly what the porter has been doing. He is incredibly volume concious and hasn't increased the port size at all up to this point. I guess he's on the right track.

I guess I should worry less about the flow numbers and just see how they turn out.

DenzSS

Current flow numbers from my porter. 28" on the flowbench if I remember correctly.

Intake
.100 68
.200 145
.300 200
.400 278
.450 268
.500 271
.550 270
.600 273

Exhaust
.100 57
.200 113
.300 153
.400 186
.500 210
.600 225

PAULJ99Z: Looks like he's hitting the .550 problem you mentioned. Well, at least to as much of a neophyte to head design as I am it does. I read your posts to him and he said it explained the situation quite well.

<small>[ August 22, 2002, 08:12 PM: Message edited by: DenzSS ]</small>

Paul J.

Looks like the flow at .400" is a little high, probably should be around 245 CFM. It appears the port is saturating at .500" lift but looks good from .200" to .500". Additional HP could be gained by working the short side radius further if a .550" lift cam is used. Have the porter flow the intake with the manifold bolted to the head to really see how the port is working. With the additional restriction, the port may saturate at a higher lift. Can the porter measure swirl through swirlmeter RPM? I believe this should also be measured and compared with the stock head.

Paul J.

DenzSS

Thanks Paul. I'll pass it that on to him.

I'm hoping to run a 224-226 .570 -.580 114 XE-R. Or at least somewhere around there. No reason to go more than the heads though.

JimmyKash

good heads aren't about flow numbers....to a point

you want as much flow as possible under the curve.....almost like a dyno

The more airflow you can get out of your heads in the .200-.500 range the BETTER.....you dont want to lost any flow from that range and just gain maybe 20cfm @ .650 lift when you wouldn't use it anyhow

PAULJ99Z

You also should notice that no sponsor advertises intake port volume, and they may not want you to know. This is an important factor when choosing a head. If the flow rate and port volume were advertised, it may be easier when choosing a head for a particular application.

A head flowing 300 CFM at 220 cc port volume will be better in my opinion than one that flows 300 CFM at 240 cc port volume at the same valve lift. It is also much more difficult and time comsuming to do the former than the latter in terms of R&D time and effort.

Use the ratio (Flow in CFM)/(Port Volume in cc) as a guide. This measurement combined with the total flow area under the lift curve will be a good measure of the heads performance. I try to keep port volumes in the 210-215 cc range for street use and 346 CI engines.

Paul J.