Exhaust Flow Numbers on Heads

95mustanggt · 01-31-2002, 05:54 PM

I have a god idea about the flow intake flow rate on cylinder heads, but how does the exhaust flow rate change how the engine performs.

The reason I'm asking is that the AFR's have more exhuast flow than TFS heads and I'm trying to consider which head to go with (in the near future).

fantozi · 02-01-2002, 01:49 AM

Check this link out **

http://albany.isoa.net/~mharrisj/fordhead.html

Steve

red82gt · 02-01-2002, 02:13 PM

I think your exhaust (headers, h or x pipe) will make more of a difference in how your engine will perform than a couple more cfm's from one head over the other. Since the exhaust is sucked out of the head by the scavenging of the headers and pumped out by the pistons you obviously don't need as high of exhaust flow as intake (Wait a minute, you're an engineer so there's no need for me to state the obvious). Anyways I believe that both heads have enough exhaust flow to support the intake flow and since the TFS heads are usually a couple hundred dollars less (Actually about $400 less for those of us still stuck here in Canada

) and not to mention they respond well to a basic port job whereas the AFR's are already CNC ported, I'd look that way.

Stang Runner · 02-01-2002, 02:25 PM

I realy like my AFR heads. it is Up to you they both are very good heads the TFS TW with a little port work would be right about the same. I went with the AFR heads myself.

Unit 5302 · 02-02-2002, 01:55 AM

To my understanding, you want exhaust flow at 75% for a N/A engine, and 80% for a S/C.

Mach 1 · 02-02-2002, 03:03 AM

thats easy, go with the AFR's. completly CNC ported, however, AFR uses cheap valve springs, so you might want to upgrade those if using a large lift cam.

95mustanggt · 02-04-2002, 11:09 AM

Thanks guys. I wasn't sure why the AFR's had so much exhuast flow compared to the TFS heads. I was looking for that 75% rule of thumb answer I guess.

01-31-2002, 05:54 PM	#1
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Exhaust Flow Numbers on Heads I have a god idea about the flow intake flow rate on cylinder heads, but how does the exhaust flow rate change how the engine performs. The reason I'm asking is that the AFR's have more exhuast flow than TFS heads and I'm trying to consider which head to go with (in the near future). __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

02-01-2002, 02:13 PM	#3
red82gt Sober voice of Reason Join Date: Nov 1998 Location: Kelowna, B.C., Canada Posts: 1,514	I think your exhaust (headers, h or x pipe) will make more of a difference in how your engine will perform than a couple more cfm's from one head over the other. Since the exhaust is sucked out of the head by the scavenging of the headers and pumped out by the pistons you obviously don't need as high of exhaust flow as intake (Wait a minute, you're an engineer so there's no need for me to state the obvious). Anyways I believe that both heads have enough exhaust flow to support the intake flow and since the TFS heads are usually a couple hundred dollars less (Actually about $400 less for those of us still stuck here in Canada ) and not to mention they respond well to a basic port job whereas the AFR's are already CNC ported, I'd look that way. __________________ 393W: AFR 205's, hydraulic roller, TKO600.

02-01-2002, 02:25 PM	#4
Stang Runner Registered Member Join Date: Jun 1999 Location: Walker, MI, USA Posts: 1,202	I realy like my AFR heads. it is Up to you they both are very good heads the TFS TW with a little port work would be right about the same. I went with the AFR heads myself. __________________ Engine: steel mounts, Under drive pulleys, K&N, GT-40 Intake ported Lower, No power steering, No A/C, Mac cold intake, 65MM TB, 255 Fuel pump, 24's, AFR 165 58cc, Rocker Arms 1.7with the stock Cam, 1 5/8 short headers, offRoad X-pipe Drive Train: 3.55, T-5 with a Pro 5.0 shifter 12.656@107.71MPH See It at www.T-racing.com/mustang.htm

02-02-2002, 03:03 AM	#6
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	thats easy, go with the AFR's. completly CNC ported, however, AFR uses cheap valve springs, so you might want to upgrade those if using a large lift cam. __________________ 2002 GT 1993 GT (SOLD) '93 Mustang GT RHC member #142 Last edited by Mach 1; 02-02-2002 at 03:50 AM..

02-04-2002, 11:09 AM	#7
95mustanggt Registered Member Join Date: May 2000 Location: Kamloops, BC Posts: 2,875	Thanks guys. I wasn't sure why the AFR's had so much exhuast flow compared to the TFS heads. I was looking for that 75% rule of thumb answer I guess. __________________ 1995 Mustang GT 20016 F150 Lariat Super Crew

02-01-2002, 01:49 AM	#2
fantozi Registered Member Join Date: Aug 2001 Location: Albuq, NM Posts: 21	Check this link out ** http://albany.isoa.net/~mharrisj/fordhead.html Steve

02-02-2002, 01:55 AM	#5
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	To my understanding, you want exhaust flow at 75% for a N/A engine, and 80% for a S/C.

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