GT40p heads

White5.0 · 01-02-2001, 12:47 AM

does anyone hear have gt40p heads? if so what do you think of them ?

Jeff Chambers · 01-02-2001, 07:31 AM

Great heads. I've made 325RWHP and 352 ft-lbs with unported GT40P and GT-40 intake with a custom .500" lift cam.

They're a great value for someone looking to stay with a cast iron head or race in one of the 'stocker' type classes.

------------------
Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH
http://www.kellnet.com/chambers

Skankin · 01-02-2001, 11:55 AM

I think they're a GREAT street head too... the smaller ports & runners provide some nice flow velocity and low to mid torque.

The stock castings aren't machined too well, so there's some nice gains with a bit of work. A streetable 325FWHP would be quite reasonable (Jeff's making more, but I presume he's running HIGH compression, and making that power at a fairly high RPM... 6000 or so?).

Here's the best source of info: http://www.geocities.com/MotorCity/Pit/5755/gt40p.html

I recommend bare heads ($200), and doing a bowl blend and exhaust runner cleanup yourself. Then a 0.030" mill for 10:1 compression, and a good valve job.

I think spending a little extra for the manley race flow valves ($195) is worth it (OEM=$75).

A crane 2030/2031 cam kit is a great, budget, streetable match ($205 including springs etc).

You definitely need an intake to take advantage of the heads breathing though.

------------------
'89.5 5L LX, hatch, Medium Canyon Red, 155K Km (No winters), 5sp, 3.08, GT interior, a/c, Alpine CD, K/N, Crane PS91, Walbro 190 LPH, March Pulleys, Mr. Gasket 180 therm (HP balanced), 3 core rad, MarkVIII fan, Variflow controller, Polygraphite front bushings, FMS-5300B springs, 6 KYB's, 73mm Calipers, Maximum Motorsport 4pt chassis brace, Western Motorsport Racing's Sub-frame connectors. Re-ringed bottom end, conv. motor mounts, melling oil pump, FMS-C50 waterpump, GT40P heads (blended, polli

Jeff Chambers · 01-02-2001, 12:30 PM

Peak torque at about 4000rpm and peak HP at about 5200rpm. The peaks, and curves for that matter, really aren't much different than when I was running regular GT-40's with an E303 cam...the curves are just shifted upwards. The P's just have fantastic runner velocities to them though which help fill the chambers with more air...and we all know what more air means. And the combustion chambers help get it all burnt better so there's more power to extract from the mixture.

Yeah, I've got a little bit more compression than stock...just a little ;^)

------------------
Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers

[This message has been edited by jeff chambers (edited 01-02-2001).]

Skankin · 01-02-2001, 04:29 PM

hmmm... I thought you'd be running a crazier cam than that ;-) I guess you can only go so far before you loose your cylinder pressure... and with only .500" lift, you're probably limited in duration as well.

Jeff Chambers · 01-02-2001, 07:06 PM

We're limited to .500" lift by rule in Trophy Stock (Pure Street as well). Duration is not limited by rule, but definitely is a consideration when designing the cam.

------------------
Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH
http://www.kellnet.com/chambers

White5.0 · 01-02-2001, 10:34 PM

thanks for the info guys, im planning on porting these heads and there going on a 347 with a f303 cam

Jeff Chambers · 01-03-2001, 07:42 AM

Boy, I don't know about running the GT-40P's on a 347 with F303. Even ported, you're looking at intake flows of 230cfm max and exhaust of maybe 170cfm max, and those are with perfect port jobs. With the added displacement of the 347, you just may not be able to get the amount of flow that the engine wants. Have you considered something like the AFR or Dart Jr heads? The P's are great with a 302/306 combination, but I'd be looking at a different head for a 347.

------------------
Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH
http://www.kellnet.com/chambers

LOCASH · 01-03-2001, 08:40 AM

Hey Jeff, Do you think they would work well with a supercharger?

------------------
86 GT T-tops, AOD, B&M shift kit and hammer shifter, ROH wheels, K&N, Timing,MAC headers, 2.5 off road H, 2.5 American Thunder, 87 spindles, rear disc,SS lines, BBK 1.5, poly bushings, Crutchfield front kick panel speakers.

1989GT · 01-03-2001, 08:59 AM

Yeah I'm also running the heads and like them a lot. All with no port work. I would look into some other heads for a 347. I think the heads will work well with a supercharger although they make a badass NA head. And the nice thing is it'll run well with out the supercharger.

------------------
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

Jeff Chambers · 01-03-2001, 10:37 AM

The blower would help in forcing air past the small valves, but again, for the higher horsepower applications you'd be better off with another head. I could see using the P's on a mild street application with maybe up to a 9psi blower (with a small cam), but anything over that and I really thing the P's become an obstruction. You've got to think of the P head as an improved stock head. If you're really going after major power increases, you've got to reduce the obstructions by going with larger ports and valves...like with the TFS or Dart heads. By the time you spend your money on the P's with serious work for high HP (such as larger valves, valve guides, stage II or III port work), you're only going to get flow equivalent to an out-of-the-box TFS, AFR, or Dart head. I love the P's, but if I weren't restricted to them by the class rules, you can bet I'd be running something else.

------------------
Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH
http://www.kellnet.com/chambers

Fox89GT · 01-03-2001, 06:10 PM

Is there somewhere you can get these already built up and ready to bolt on? Also, being from California, are these emissions legal?

Jeff Chambers · 01-03-2001, 07:17 PM

Central Coast Mustang out of Florida sells them built with quality components and drilled for the air tube. You should be able to find CCM on the web.

------------------
Jeff Chambers
Trophy Stock #3
11.97 Seconds / 114.5 MPH
http://www.kellnet.com/chambers

Skankin · 01-04-2001, 01:26 PM

If you were using the P's with a blower, you'd definitely wanna cool the charge. The Iron just doesn't conduct the heat away like an Aluminum head will. The exhaust runner could certainly be cleaned up to get a nice 80% exhaust:intake ratio.

As for the 347, it depends on your intentions. The P's would make a wicked street combo, but you'd be limited with higher RPM. If I remember correctly, they did make more power (up to 5800RPM) than the Sr's on a 351 combo.

You may want a little more cam than the F... depending on the application, gearing, etc.

Panhandle Performance advertises the P's, and there's another company that has a pretty good deal.

If emissions is a concern, CCM is the only company that does the thermactor hookup.

White5.0 · 01-04-2001, 09:56 PM

thanks for all the info guys, im just trying to get all the opinions i can,im wanting to build a mild engine, nothing really wicked, im running 3.73's and getting ready to convert from aod to a t5 that im taking out of my other mustang i have for parts, im gonna be using a edelbrock performer rpm dual plane intake with the holley projection 4d, the injection is rated 550hp, and im looking for around 400. i want my engine to make power up to 6000 rpm maybe 6500, but as you all have informed the P heads wont breathe that far without a lot of porting, thanks for all your info an time.
eric

01-02-2001, 12:47 AM	#1
White5.0 Registered Member Join Date: Dec 2000 Location: VA Posts: 80	GT40p heads does anyone hear have gt40p heads? if so what do you think of them ?

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01-02-2001, 07:31 AM	#2
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Great heads. I've made 325RWHP and 352 ft-lbs with unported GT40P and GT-40 intake with a custom .500" lift cam. They're a great value for someone looking to stay with a cast iron head or race in one of the 'stocker' type classes. ------------------ Jeff Chambers Trophy Stock #3 11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers

01-02-2001, 11:55 AM	#3
Skankin Registered Member Join Date: Dec 1998 Location: London, Ontario, Canada Posts: 1,349	I think they're a GREAT street head too... the smaller ports & runners provide some nice flow velocity and low to mid torque. The stock castings aren't machined too well, so there's some nice gains with a bit of work. A streetable 325FWHP would be quite reasonable (Jeff's making more, but I presume he's running HIGH compression, and making that power at a fairly high RPM... 6000 or so?). Here's the best source of info: http://www.geocities.com/MotorCity/Pit/5755/gt40p.html I recommend bare heads ($200), and doing a bowl blend and exhaust runner cleanup yourself. Then a 0.030" mill for 10:1 compression, and a good valve job. I think spending a little extra for the manley race flow valves ($195) is worth it (OEM=$75). A crane 2030/2031 cam kit is a great, budget, streetable match ($205 including springs etc). You definitely need an intake to take advantage of the heads breathing though. ------------------ '89.5 5L LX, hatch, Medium Canyon Red, 155K Km (No winters), 5sp, 3.08, GT interior, a/c, Alpine CD, K/N, Crane PS91, Walbro 190 LPH, March Pulleys, Mr. Gasket 180 therm (HP balanced), 3 core rad, MarkVIII fan, Variflow controller, Polygraphite front bushings, FMS-5300B springs, 6 KYB's, 73mm Calipers, Maximum Motorsport 4pt chassis brace, Western Motorsport Racing's Sub-frame connectors. Re-ringed bottom end, conv. motor mounts, melling oil pump, FMS-C50 waterpump, GT40P heads (blended, polli

01-02-2001, 12:30 PM	#4
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Peak torque at about 4000rpm and peak HP at about 5200rpm. The peaks, and curves for that matter, really aren't much different than when I was running regular GT-40's with an E303 cam...the curves are just shifted upwards. The P's just have fantastic runner velocities to them though which help fill the chambers with more air...and we all know what more air means. And the combustion chambers help get it all burnt better so there's more power to extract from the mixture. Yeah, I've got a little bit more compression than stock...just a little ;^) ------------------ Jeff Chambers Trophy Stock #3 11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers [This message has been edited by jeff chambers (edited 01-02-2001).]

01-02-2001, 04:29 PM	#5
Skankin Registered Member Join Date: Dec 1998 Location: London, Ontario, Canada Posts: 1,349	hmmm... I thought you'd be running a crazier cam than that ;-) I guess you can only go so far before you loose your cylinder pressure... and with only .500" lift, you're probably limited in duration as well.

01-02-2001, 07:06 PM	#6
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	We're limited to .500" lift by rule in Trophy Stock (Pure Street as well). Duration is not limited by rule, but definitely is a consideration when designing the cam. ------------------ Jeff Chambers Trophy Stock #3 11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers

01-02-2001, 10:34 PM	#7
White5.0 Registered Member Join Date: Dec 2000 Location: VA Posts: 80	thanks for the info guys, im planning on porting these heads and there going on a 347 with a f303 cam

01-03-2001, 07:42 AM	#8
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Boy, I don't know about running the GT-40P's on a 347 with F303. Even ported, you're looking at intake flows of 230cfm max and exhaust of maybe 170cfm max, and those are with perfect port jobs. With the added displacement of the 347, you just may not be able to get the amount of flow that the engine wants. Have you considered something like the AFR or Dart Jr heads? The P's are great with a 302/306 combination, but I'd be looking at a different head for a 347. ------------------ Jeff Chambers Trophy Stock #3 11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers

01-03-2001, 08:40 AM	#9
LOCASH Registered Member Join Date: Oct 2000 Location: Santa Lucia di Budoia, Italy Posts: 217	Hey Jeff, Do you think they would work well with a supercharger? ------------------ 86 GT T-tops, AOD, B&M shift kit and hammer shifter, ROH wheels, K&N, Timing,MAC headers, 2.5 off road H, 2.5 American Thunder, 87 spindles, rear disc,SS lines, BBK 1.5, poly bushings, Crutchfield front kick panel speakers.

01-03-2001, 08:59 AM	#10
1989GT Registered Member Join Date: Apr 1999 Location: Cincinnati,OH Posts: 1,511	Yeah I'm also running the heads and like them a lot. All with no port work. I would look into some other heads for a 347. I think the heads will work well with a supercharger although they make a badass NA head. And the nice thing is it'll run well with out the supercharger. ------------------ 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

01-03-2001, 10:37 AM	#11
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	The blower would help in forcing air past the small valves, but again, for the higher horsepower applications you'd be better off with another head. I could see using the P's on a mild street application with maybe up to a 9psi blower (with a small cam), but anything over that and I really thing the P's become an obstruction. You've got to think of the P head as an improved stock head. If you're really going after major power increases, you've got to reduce the obstructions by going with larger ports and valves...like with the TFS or Dart heads. By the time you spend your money on the P's with serious work for high HP (such as larger valves, valve guides, stage II or III port work), you're only going to get flow equivalent to an out-of-the-box TFS, AFR, or Dart head. I love the P's, but if I weren't restricted to them by the class rules, you can bet I'd be running something else. ------------------ Jeff Chambers Trophy Stock #3 11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers

01-03-2001, 06:10 PM	#12
Fox89GT Registered Member Join Date: Sep 2000 Location: Bay Area, CA Posts: 55	Is there somewhere you can get these already built up and ready to bolt on? Also, being from California, are these emissions legal?

01-03-2001, 07:17 PM	#13
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Central Coast Mustang out of Florida sells them built with quality components and drilled for the air tube. You should be able to find CCM on the web. ------------------ Jeff Chambers Trophy Stock #3 11.97 Seconds / 114.5 MPH http://www.kellnet.com/chambers

01-04-2001, 01:26 PM	#14
Skankin Registered Member Join Date: Dec 1998 Location: London, Ontario, Canada Posts: 1,349	If you were using the P's with a blower, you'd definitely wanna cool the charge. The Iron just doesn't conduct the heat away like an Aluminum head will. The exhaust runner could certainly be cleaned up to get a nice 80% exhaust:intake ratio. As for the 347, it depends on your intentions. The P's would make a wicked street combo, but you'd be limited with higher RPM. If I remember correctly, they did make more power (up to 5800RPM) than the Sr's on a 351 combo. You may want a little more cam than the F... depending on the application, gearing, etc. Panhandle Performance advertises the P's, and there's another company that has a pretty good deal. If emissions is a concern, CCM is the only company that does the thermactor hookup.

01-04-2001, 09:56 PM	#15
White5.0 Registered Member Join Date: Dec 2000 Location: VA Posts: 80	thanks for all the info guys, im just trying to get all the opinions i can,im wanting to build a mild engine, nothing really wicked, im running 3.73's and getting ready to convert from aod to a t5 that im taking out of my other mustang i have for parts, im gonna be using a edelbrock performer rpm dual plane intake with the holley projection 4d, the injection is rated 550hp, and im looking for around 400. i want my engine to make power up to 6000 rpm maybe 6500, but as you all have informed the P heads wont breathe that far without a lot of porting, thanks for all your info an time. eric