Gt-40 Irons, how much hp?

chris91LX · 02-02-2001, 01:53 AM

I'm looking at a set of GT-40 iron heads. How much horsepower can I expect to gain. I'll probably add the Trick Flow intake and a fuel pressure regulator. The heads are supposedly mildly ported w/ 1.6 roller rockers. I have a stock block and the mods listed below. Anyone give me an idea of what I can expect? I ran a best of 14.01 @ 98.7mph with the mods listed (minus the mac cold air kit) and never got a great run in last year. How much ET should I pick up with the heads and intake? Thanks in advance guys!

------------------
91 LX 5.0
Z t-5, 3:73 gear, Vortech 73mm Mass Air, Accufab 65mm TB, BBK underdrives, Crane HI-6S Ignition, BBK unequal length headers, Bassani x pipe, 2.5" Dynomax Super Turbo cat back, Kenny Brown Super Subs, Factory Five Control Arms, Mac cold air kit and more to come!

02-02-2001, 03:02 AM

When these heads are installed on a stock motor,it is claimed to provide an additional 25HP over the stock heads.

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Paxton Blown 87GT

Josh91 · 02-02-2001, 10:15 AM

Adding those heads and intake ought to get you around 25-30HP. If the port job is really good, you could expect upwards of 35, maybe a tad more.

------------------
1991 Mustang GT - Cobra Intake, FMS 65mm TB, C&L 73mm MAF, GT-40P heads, Crane 2031 cam, Crane 1.7rr, Built AOD, Art Carr 2400 non-lockup converter, Transgo shift kit, BBK chrome cold air, FMS 'P' headers, Pacesetter off-road H, BBK aluminum pulleys, 2-C Flows w/ dumps, 4.10's, Steeda STB, for now...

The Original GT-40P Tech Page

chris91LX · 02-03-2001, 02:11 AM

That doesn't seem like much. I might have found a deal on complete heads, the GT40's. I was saving for the AFR 165's, but figured at less than half the cost I could get a little less horsepower alot quicker. I've heard I can get almost 80hp out of new aluminum heads, is that an exageration?

red82gt · 02-03-2001, 02:49 AM

80 hp out of aluminum heads...maybe with 1 3/4" longtubes and a solid roller cam. I remember seeing a dyno test a few years back in Super Ford and a box stock set of GT-40 irons added 28 rwhp on a bone stock motor with no other breathing mods except a K&N filter. The GT-40's like exhaust work so I'll bet you'll see about 40 at the wheels. Also remember tha Iron transfers heat better than aluminum so a ported Iron head will make good power-especially if you're going to stay naturally aspirated.

------------------
GT-40 heads (ported, polished, + milled), B303 cam, 1.7rr's, JE pistons, Offy intake, Carter AFB 625cfm carb, Flowtech 1 5/8" shortys, Flowtech X-pipe, MAC Flowpath exhaust, MAC pulleys, 373's, subframes, Eibachs+Tokicos, B+M ripper, FMS Clutch, Zoom Quadrant+cable, 17" CSA Ultra rims, 235/45ZR17 Yokohama AVS S4's, MSD 6A ignition+coil, FMS 9mm wires, Carbed, Naturally Aspirated, and Nasty!

1989GT · 02-03-2001, 12:04 PM

I'll bet if you pick up that intake and the heads and some sticky tires and you'll see 12's.

------------------
89GT,T-5Z, D.S.S. 306 shortblock w\main support, B-303 cam, Cobra intake, GT40P heads, 1.72rr, MAC "P" headers, MAC off-road H-Pipe, MAC true-fit w\tips, 373's...and the list goes on!
Throttle Junkie Powered by Ford!
12.824 @ 107.05 MPH
PVT Blankenship leaving for BCT 14MAR01
MOS 67 Romeo

chris91LX · 02-03-2001, 02:08 PM

That's more what I'm looking for. Like I said, I've heard some guys on this board trashing the iron heads and claiming the aluminums get twice the hp. I figured for 1/3rd the price I would seriously consider the irons. I am planning on staying naturally aspirated for now so that sounds good red82GT. Does anyone know about what hp difference I would be looking at iron GT40's vs. AFR 165's with the same setup?

02-02-2001, 01:53 AM	#1
chris91LX Registered Member Join Date: Oct 1998 Location: Suburban Chicago, Hanover Park Posts: 695	Gt-40 Irons, how much hp? I'm looking at a set of GT-40 iron heads. How much horsepower can I expect to gain. I'll probably add the Trick Flow intake and a fuel pressure regulator. The heads are supposedly mildly ported w/ 1.6 roller rockers. I have a stock block and the mods listed below. Anyone give me an idea of what I can expect? I ran a best of 14.01 @ 98.7mph with the mods listed (minus the mac cold air kit) and never got a great run in last year. How much ET should I pick up with the heads and intake? Thanks in advance guys! ------------------ 91 LX 5.0 Z t-5, 3:73 gear, Vortech 73mm Mass Air, Accufab 65mm TB, BBK underdrives, Crane HI-6S Ignition, BBK unequal length headers, Bassani x pipe, 2.5" Dynomax Super Turbo cat back, Kenny Brown Super Subs, Factory Five Control Arms, Mac cold air kit and more to come!

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02-02-2001, 03:02 AM	#2
Mustanguy Guest Posts: n/a	When these heads are installed on a stock motor,it is claimed to provide an additional 25HP over the stock heads. ------------------ Paxton Blown 87GT

02-02-2001, 10:15 AM	#3
Josh91 Registered Member Join Date: Nov 1998 Location: Salina, KS Posts: 83	Adding those heads and intake ought to get you around 25-30HP. If the port job is really good, you could expect upwards of 35, maybe a tad more. ------------------ 1991 Mustang GT - Cobra Intake, FMS 65mm TB, C&L 73mm MAF, GT-40P heads, Crane 2031 cam, Crane 1.7rr, Built AOD, Art Carr 2400 non-lockup converter, Transgo shift kit, BBK chrome cold air, FMS 'P' headers, Pacesetter off-road H, BBK aluminum pulleys, 2-C Flows w/ dumps, 4.10's, Steeda STB, for now... The Original GT-40P Tech Page

02-03-2001, 02:11 AM	#4
chris91LX Registered Member Join Date: Oct 1998 Location: Suburban Chicago, Hanover Park Posts: 695	That doesn't seem like much. I might have found a deal on complete heads, the GT40's. I was saving for the AFR 165's, but figured at less than half the cost I could get a little less horsepower alot quicker. I've heard I can get almost 80hp out of new aluminum heads, is that an exageration?

02-03-2001, 02:49 AM	#5
red82gt Sober voice of Reason Join Date: Nov 1998 Location: Kelowna, B.C., Canada Posts: 1,514	80 hp out of aluminum heads...maybe with 1 3/4" longtubes and a solid roller cam. I remember seeing a dyno test a few years back in Super Ford and a box stock set of GT-40 irons added 28 rwhp on a bone stock motor with no other breathing mods except a K&N filter. The GT-40's like exhaust work so I'll bet you'll see about 40 at the wheels. Also remember tha Iron transfers heat better than aluminum so a ported Iron head will make good power-especially if you're going to stay naturally aspirated. ------------------ GT-40 heads (ported, polished, + milled), B303 cam, 1.7rr's, JE pistons, Offy intake, Carter AFB 625cfm carb, Flowtech 1 5/8" shortys, Flowtech X-pipe, MAC Flowpath exhaust, MAC pulleys, 373's, subframes, Eibachs+Tokicos, B+M ripper, FMS Clutch, Zoom Quadrant+cable, 17" CSA Ultra rims, 235/45ZR17 Yokohama AVS S4's, MSD 6A ignition+coil, FMS 9mm wires, Carbed, Naturally Aspirated, and Nasty!

02-03-2001, 12:04 PM	#6
1989GT Registered Member Join Date: Apr 1999 Location: Cincinnati,OH Posts: 1,511	I'll bet if you pick up that intake and the heads and some sticky tires and you'll see 12's. ------------------ 89GT,T-5Z, D.S.S. 306 shortblock w\main support, B-303 cam, Cobra intake, GT40P heads, 1.72rr, MAC "P" headers, MAC off-road H-Pipe, MAC true-fit w\tips, 373's...and the list goes on! Throttle Junkie Powered by Ford! 12.824 @ 107.05 MPH PVT Blankenship leaving for BCT 14MAR01 MOS 67 Romeo

02-03-2001, 02:08 PM	#7
chris91LX Registered Member Join Date: Oct 1998 Location: Suburban Chicago, Hanover Park Posts: 695	That's more what I'm looking for. Like I said, I've heard some guys on this board trashing the iron heads and claiming the aluminums get twice the hp. I figured for 1/3rd the price I would seriously consider the irons. I am planning on staying naturally aspirated for now so that sounds good red82GT. Does anyone know about what hp difference I would be looking at iron GT40's vs. AFR 165's with the same setup?