GT40 heads

[speedfreek95gt]

I'm looking into building a fresh, forged bottom end for my 95. I've read everything from complete bs to unproved testimonials about how much power you can really get out of a set of cast GT40 heads. Some places sell ported/polished GT40's with upgraded springs and valves for $595 plus core. What I'm looking for is anyone who has built any type of bottom end, 306, 331, 347, ect and thrown a set of ported and polished cast GT40 heads on them and the springs/valves/rockers used and which cam. I'm not looking to pry into anyone's secret build, I'm just trying to find out what's really going to be the best bang for the buck. I like to laugh at people who brag about "going big" and then turn around and find something that made more power for 1/4 of the price they tell everyone they spent. Based on my findings, that will help me decide what setup I should look into. I'm not shooting for anything ridiculous, anywhere from 300-400 rwhp. Thats plenty for the streets and I show my car more than I drag race it, so that should sum up what I'm going to use it for. Again, not trying to steal anyone's setup (guys on some forums REALLY get ticked about threads like these...) I'd just like to see some proven results for some GT40 head setups so I can build something just as efficient, strong, and powerful as those guys who drop $4k into a motor unnecessarily. I will post below my current mods list I have on my STOCK 95 bottom end. I'll be using as much as I can off of the car now with the fresh bottom end. If something won't fit (ie: BBK headers on the GT40 heads) please let me know. Any and all input is greatly appreciated!

Current modifications:

Trick Flow Track Heat Intakes
FRPP E303 Cam
Ford Racing Valve Covers
BBK 70mm Throttle Body
FRPP 70mm MAF
Walbro 255 LPH Fuel Pump
Kirban Fuel Pressure Regulator
BBK CAI
BBK Pullies
BBK Shorty Headers
MSD Blaster Coil
MSD 6AL Ignition
BBK Off Road H
Flowmaster 40's
MAC 2.5" Tailpipes
Tremec 3550 5 Speed
UPR Adjustable Cable/Quadrant
Pro 5.0 Shifter
3.73 Gears
B&M Line Lock
FRPP Rear End Girdle
Ratech Diff Kit
Kenny Brown Strut Tower Brace
Saleen S281 Spoiler
Steeda Suspension
17x9, 10.5 Black Bullitts w/HTR-Z's
Mickey Thompson ET Streets
Autometer Sport-Comp Oil Pressure and Water Temp Gauges & Tach
FRPP A-Pillar Pod
Tweecer R/T

 

[LAFENATU]

Just curious to why you are looking to build a forged bottom end?

My experience with GT40 heads:

1992 Mustang LX 5.0L

12.81@106 - 262rwhp

K&N Panel Filter
C&L 73mm MAF
Mac 70mm TB
GT40 Tubular Intake
Ported GT40 Cast Iron Heads
Crane 2031 Camshaft
Crane 1.7 Roller Rockers
24lb injectors
BBK Shorty Headers
Mac Prochamber
Flowmaster Catback
3.73's
T-5 Trans


1995 Mustang GT 5.0L

No track times - 251rwhp

UPR Cold Air Intake
Pro-M 75mm MAF
FRPP 65mm TB
GT40 Tubular Intake
GT40 Cast Iron Heads
Crane 1.7 Roller Rockers
24lb injectors
Stock GT Cam
FRPP Shorty Headers
Mac Prochamber
Flowmaster Catback
3.73's
2500 Stall Converter
PA Competition AOD-E


My buddy Eric's 92 LX

12.70 @ 107.83


K&N Panel Filter
Pro-M 75mm
FRPP 65mm TB
Edelbrock Performer Intake
Ported GT40 Heads
FRPP 1.72 Rockers
Crane 2031 cam
Mac underdrive pulleys
FRPP ceramic coated shorty headers
Mac Prochamber
Dynomax Ultraflo Catback
3.73's
T-5z Trans

 

[speedfreek95gt]

My motor is approaching 100,000 miles and with it having hypereutectic internals, if I'm going to pull it and rebuild it, I might as well rebuild it ONCE to handle anything I can potentially throw at it in the future. I hate spending money twice, so the objective here is to build a bottom end to hold the max I ever plan on having, which is some type of forced induction. Cams, heads, intakes, ect are easy to swap out to change a setup, throwing rods and pistons through a block and the top end ruin your day and potentially your entire setup. The info you posted was exactly what I was looking for (thank you). What type of port job did you have done (stage?) and what company did you use? The setup I have now put 263 to the wheels, 307 ft lbs of torque.

 

[LAFENATU]

The info you posted was exactly what I was looking for (thank you). What type of port job did you have done (stage?) and what company did you use? The setup I have now put 263 to the wheels, 307 ft lbs of torque.

Your Welcome

The 92 LX heads were ported by my buddy who has been doing it professionally for a long time. He is in wisconson, I had them shipped there. He did not do a full out port on the heads, he gasket matched the intake and ported the exhaust to match my BBK headers. Did a 3-angle valve job, blended the bowls, and installed new TFS .550 lift chromoly retainers and valve springs.

The 95 are basically a stock GT40 Head that were Extrude Honed with a multi-angle valve job.

Eric's 92 LX has 93 Cobra GT40's that were ported from the previous owner. He is not sure who did it.

 

[speedfreek95gt]

Generally speaking, what is a ball park figure for the port work and valve jobs? The local shop I'd take mine to tend to be a bit more expensive than most places, and you don't by any means get anything extra or a "better job". It just so happens they're one of the very few people in town who can do the work, so people take their stuff there and just bite the bullet. I've seen heads themselves go for between $200 and $400 in "stock" form. I wouldn't mind shipping the heads out to another shop to have them done, I'd just like to get an idea of what I'm going to be spending.

 

[95 svt cobra]

thumper or steigs does it, and they have a good reputation. I am also in the market for porting currently

 

[speedfreek95gt]

I looked at Thumpers site, however they only advertise work on E7's (or at least that's what they sell). I will call them and see what they would charge for me to send in a set of heads and just have the machine work done.

 

[BlkoutGT]

hey i just glanced at this months issue of muscle mustangs and ff ... there budget minded fox just got E7's port and polished from Thumper, and the article just said that they offer many different things like port and polish, to bigger valves, better springs and such on e7's, Gt40 p and Gt40s... with like 100 refundable core charged... deffiinitly worth a look at/ call to... since there website is vague

 

[speedfreek95gt]

Cool, thanks! I'll give them a call tomorrow and get some figures. I'll post what I find out since theres a few other guys looking too.

 

[Win]

My motor is approaching 100,000 miles .

HEHE i will soon be approvaching 200,000 miles and im still going strong. Yeah i am still stock but if a motor can take a beating i can throw at it you know its a good motor.

Why not step up and get a set of AFR's . Once you spend the money on GT40's and a valve and porting your going to be up there with a set of AFR's ? You were talking about doing it once so you dont have to spend the money so why not.

 

[95 svt cobra]

Im pretty sure a set of ported GT40's will outflow some unported AFR's

 

[speedfreek95gt]

I'll have (based on other's experiences) around $650 in a set of GT40's ported and polished, including the price of the heads. Any set of AFR'S I've looked at unported start at $1,000. My thoughts were to throw the GT40's on the current motor and drive that until I have a new motor built. I have some longterm plans to buy my first car (86 notch) back in the distant future. If that's the case, I'll have another complete motor to drop in there and toy with.

My 91 GT I had I think turned 176,000 miles before I got rid of it. That motor ran strong still to that day. The motor I have now isn't faulty in the least, I would just rather not completely implode it with any type of FI. It makes for good entertainment but that'd also make one heck of a mess.

 

[Win]

I'll have (based on other's experiences) around $650 in a set of GT40's ported and polished, including the price of the heads. Any set of AFR'S I've looked at unported start at $1,000. My thoughts were to throw the GT40's on the current motor and drive that until I have a new motor built. I have some longterm plans to buy my first car (86 notch) back in the distant future. If that's the case, I'll have another complete motor to drop in there and toy with.

My 91 GT I had I think turned 176,000 miles before I got rid of it. That motor ran strong still to that day. The motor I have now isn't faulty in the least, I would just rather not completely implode it with any type of FI. It makes for good entertainment but that'd also make one heck of a mess.

yeah i was just thinking if you went AFR's you could always down the road get a lot more out of them then the Gt40's but since your talking about a new motor later on down the road. Then yeah a set of ported gt40's would be a great idea. Ought to look into getting a upper and lower ported by TMoss also.

 

[speedfreek95gt]

I already have a Trick Flow track heat upper and lower. That's kinda my problem, I have just about every other bolt-on you can buy except heads... I'm shortchanging myself big time. :crying:

 

[Win]

When you get heads in there thats going to be a nice change Are you going to throw a cam in there when you do the head swap??

 

[speedfreek95gt]

Here's my current mods list on the car:

Trick Flow Track Heat Intakes
FRPP E303 Cam
Ford Racing Valve Covers
BBK 70mm Throttle Body
FRPP 70mm MAF
Walbro 255 LPH Fuel Pump
Kirban Fuel Pressure Regulator
BBK CAI
BBK Pullies
BBK Shorty Headers
MSD Blaster Coil
MSD 6AL Ignition
BBK Off Road H
Flowmaster 40's
MAC 2.5" Tailpipes
Tremec 3550 5 Speed
UPR Adjustable Cable/Quadrant
Pro 5.0 Shifter
3.73 Gears
B&M Line Lock
FRPP Rear End Girdle
Ratech Diff Kit
Kenny Brown Strut Tower Brace
Saleen S281 Spoiler
Steeda Suspension
17x9, 10.5 Black Bullitts w/HTR-Z's
Mickey Thompson ET Streets
Autometer Sport-Comp Oil Pressure and Water Temp Gauges & Tach
FRPP A-Pillar Pod
Tweecer R/T


* I'm going to stick with the E-cam and see where that gets me. Alot of people have ran some pretty impressive times (nothing extravagant, but fun for the streets) with a very similar mods list as mine. I just hope to open up the breathing ability of the car for now and see where it goes from there.

 

[LAFENATU]

Im pretty sure a set of ported GT40's will outflow some unported AFR's

AFR's automatically come CNC Ported

 

[stang94X]

try looking for some cheap gt40X heads, i found mine for $800, they're aluminum and a decent head out of the box, fortunately for me i got my heads all clean up ported/polished for free from my fathers friend thats been building race motors professionally since the 60's, i don't know what they flowed before the porting but afterwards they flowed well more than the afr 165's, i forget the flow numbers but they were very close to the 185's and there's still a lot more room for more porting

 

[speedfreek95gt]

Im pretty sure a set of ported GT40's will outflow some unported AFR's

AFR's automatically come CNC Ported

unported as in "out of the box"... all of my comparisons are to stock or out of the box. In other words, my previous post was comparing ported/polished GT40's for $650 outflowing AFR's out of the box for $1400.

 

[Stangbangin]

Most of the flow sheets I've seenshow ported gt40's flowing under afr's out of the box. But for the price I tihnk its a good budget minded move. AFr's are afr's but you can get into the 12's on gt40's.