GT40P Heads??? - Ranger-Forums - The Ultimate Ford Ranger Resource


8-Cylinder Tech If you are one of the few with a V8 engine in your Ranger, or if you dream of a Ranger with a V8 engine, this is the sub-forum for you.

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  #1  
Old 04-04-2007
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GT40P Heads???

I just pulled off my valve covers to discover the heads have a marking that says "GT40P".

Anyone got any info?
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Old 04-04-2007
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Quote:
Originally Posted by Needforspeed3685
I just pulled off my valve covers to discover the heads have a marking that says "GT40P".

Anyone got any info?
That's what the later 5.0 Ex's had.

The GT40P is a modified version of the GT40 Cobra heads that came standard on 97-back 5.0 Explorers. Among other things, the P has reangled spark plug holes and slightly smaller exhaust valves.

GT40P's are very good performance heads and so is the stock 5.0 Ex intake manifold. The main thing that is holding that engine back is the hideous set of stock exhaust manifolds.

Last edited by V8 Level II; 04-04-2007 at 10:15 PM.
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Old 04-04-2007
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Quote:
Originally Posted by rwenzing
That's what the later 5.0 Ex's had.

Someone needs to slap me with the Search Salmon...

I found 13 pages of information on stangpro.com....lol
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  #4  
Old 04-04-2007
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not bad, they are iron heads. and yes, stock v8 exploder heads
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  #5  
Old 04-05-2007
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According to my research, the GT-40P replaced the standard GT-40 on the V8 Explorers and Mountaineers in early 1997. These are the same heads found on the Cobra's!!!!
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Old 04-05-2007
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good heads for torque, idle-5K. wont make much above 300 RWHP though. probaly the best Ford production iron head for the EFI.

mild porting (thermactor bump be gone!), gasket match, polich the chambers, clean upthe valve throats and bowls and u are good to go.


Which cobras? AFAIK, 93-95 Corbas/lightnings used the GT40s...
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  #7  
Old 04-06-2007
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is there any difference in the exhaust ports on them? if i were to run these on my 302 would the headers from the swap kit still work?
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Old 04-06-2007
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Quote:
Originally Posted by rdy4mud
is there any difference in the exhaust ports on them? if i were to run these on my 302 would the headers from the swap kit still work?
Ordinary "swap headers" for 5.0L Rangers are for 97-back and do not fit the 98+ engine bay. There are 5 kinds of exhaust manifolds/headers that will work on a 1998+ 5.0 Ranger.

  • Stock Explorer 5.0L cast iron
  • Stock Explorer 5.0L stainless
  • FRPP Explorer 5.0L headers
  • Torque Monster Headers
  • Custom



GT40 and GT40P have about the same port outlet shape. It would be a good idea to consider spark plug wire vs. header interference since the heads have different plug angles.
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Old 04-06-2007
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Great info, Bob! Thank you very much!

* The GT-40P replaced the standard GT-40 on the V8 Explorers and Mountaineers in early 1997. Yes, that's right, the Explorers got Cobra heads (although the Cobra's heads were milled to bring it's larger combustion chamber down to the size of the E7TE to keep compression up).

* Similar runner volumes to the standard GT-40 head (around 145-155cc on the intake side, I think, compared to E7TE's 124cc). Also flows similar intake and exhaust cfm numbers to the standard GT-40 head. All accessory bolt locations and valve train geometry are the same as the standard GT-40.

* 1.85/1.46 valves (compared to 1.85/1.54 for the standard GT-40). The exhaust port was redesigned and is more efficient, thus the ability to use the smaller exhaust valve. This actually works well since to get equal flow numbers the velocity must be higher.....exactly what we want.

There's a little bit of room for larger valves but start going larger on the intake side and you're going to have to grind on that plug boss to clear it. And....don't forget.....a bigger valve isn't necessarily better. The whole reason these heads work so well is the decent flow they provide while still having smaller port dimensions. If you're not careful and hog out the bowls for big valves you could easily hurt flow. Just remember this when planning your mods.

* Smaller 59cc (up to 61cc based on factory tolerances) combustion chambers (65.5cc in unmilled GT-40 w/ FRPP valves). Great for NA cars as this equates to a raised compression ratio when switching from E7TE castings. Should get you close to 9.5:1 (w/ stock pistons). Cut 0.030" off the bottom and you're close to 10:1 (w/ stock pistons).

* Small emissions-type bump in exhaust port similar to E7TE casting but it's nowhere near as pronounced. This bump is dead center on the port roof right at the exit. Easily removed if you feel it's hurting flow. I removed mine, smoothing the transition from the guide boss to the port exit. I raised the roof of the port here to eliminate the offending bump and open the port to a size a bit closer to the Fel-Pro 1415 gasket.

* No thermactor holes in the front/rear face to plug and no hole in the exhaust port to mess up flow.

* Intake ports are already very close to a Felpro 1250 gasket...probably no need to gasket match. Mine were only off on one end.....the other three side being almost perfect. I just matched the last side.....no sweat.

* They can use stock pedestal mount rockers. I upgraded to stud-mount adjustables. Be sure to get a shim kit to ensure you'll get the rockers to torque down correctly if you're using bolt-downs. You may not need 'em if you don't mill the heads but the kit is only $10.

* Spark plug is moved down and rotated out placing the electrode closer to the center of the combustion chamber. This provides a better and more complete burn. Not only does this help performance but it also reduced emissions. Note: The GT-40P's don't use standard 5.0L plugs. You must use plugs for a 98+ Explorer/Mountaineer V8 or for a Cobra/Lightning equipped with iron GT-40 heads!! Forget about the shorty plugs (Accel p/n P526S). I've heard they're close to $10 each for this application! Plug specs are: 14mm thread, 0.708" projection, tapered seat, resistor plug. Thanks to Derek Hyde for the Accel plug specs!!. The 2000 FRPP catalog lists a Motorcraft AWSF-32C. I bought Champion Truck Plugs p/n 4013 (I used the Truck Plugs on a '97 V8 Dakota I had and was happy with them. Thought I'd try 'em again.)

* Standard unequal length shorty headers won't work because of this new plug location. The primary pipes make their downward turn towards the collector too soon. Central Coast Mustang offers a P-specific shorty (made by MAC) for $199 and FRPP is offering a set for about $250. I know the FRPP pieces are stainless.....not sure about the MAC....most likely their HTS coating. I thought I read once that stock tubular exhaust manifolds might work. Why bother using those though if you're upgrading the heads?

In starting my research for the header-fit table I've been told that standard FRPP unequal length shorties will work for not only the Fox application but the SN95 shorties will work for the 94-95 cars as well. These are not a perfect fit like the MAC-for-CCM shorties and will most likely require 90 boots and/or heat booties, but they are supposed to fit without any primary dimpling.

* Equal length shorties won't work at all. Well....sort of. Again....in researching the header-fit table it looks, via some good installed shots - don't have provider's info handy....credit will be given) that BBK equal length headers may fit. Still studying the pics for a more solid opinion on this.

* Some longtubes and 3/4 length headers will work. Their ability to allow the primaries a longer exit straight from the exhaust port b4 turning down towards the collector provides adequate access to the plug. I know of MAC longtubes (1 5/8"), Flowtech longtubes (1 5/8"), and Heddman longtubes (1 1/2") being used.

The Heddmans alledgedly require a small clearance dimple on the #4 primary. The MAC's are snug on the #7 primary but clear fine. CCM offers these as a longtube alternative to their P-specific shorties. I had unknown-brand 3/4 length headers (1 1/2") on my '84 (look like DynoMax) that will clear no sweat. MAC longtubes for the SN95's are a good fit. CCM finallyhas a SN95 P-fit shorty. CCM is also offering a set of Tri-Y headers for GT-40P use in classic Mustangs. This is a huge plus as I've had many questions regarding header fit for P's in classic 'Stangs.

The Flowtechs were originally thought to work and they can be used. The dimple that was said to be required in the #4 primary is more like a crater. You need to crush the primary half closed to clear everything. And you'll need wires with 90 to clear a few of the other primaries as well. Check out the Progress Page for more info on this. There's some great shots of the Flowtechs installed (and "dimpled") as well as the CCM MAC built P-specific shorties.

* P heads take a 7/16" headbolt just like other 289/302 heads. No funky stepped bolts or bushings needed. Big plus IMO here. Bad for 351W installs but great for us 302 based users.

Written by Sean Meldrum
StangPro.com
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  #10  
Old 04-06-2007
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Does anyone (Bob?) know if a set of long tube headers works with the coils-sprung (2wd) Ranger engine bay? I HAVE to get rid of those nasty lookin cast headers.
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Old 04-06-2007
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Quote:
Originally Posted by Needforspeed3685
Does anyone (Bob?) know if a set of long tube headers works with the coils-sprung (2wd) Ranger engine bay? I HAVE to get rid of those nasty lookin cast headers.
Regular long tube headers from other apps won't fit. The closest thing is the Torque Monsters ($689!) that are custom made to squeeze into the cramped 5.0 Explorer bay (virtually the same as the 98+ torsion bar Ranger bay). You should contact BrianB31 to see if he has any more insight about headers in the coil spring truck.







http://images.google.com/imgres?imgu...LJ:en%26sa%3DN
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Old 04-06-2007
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Quote:
Originally Posted by rwenzing
Regular long tube headers from other apps won't fit. The closest thing is the Torque Monsters ($689!) that are custom made to squeeze into the cramped 5.0 Explorer bay (virtually the same as the 98+ torsion bar Ranger bay). You should contact BrianB31 to see if he has any more insight about headers in the coil spring truck.







http://images.google.com/imgres?imgu...LJ:en%26sa%3DN
there is a kit for a 83 to 95 rangers but yeah for newer trucks there's nothing available but who knows in a future

BTW here is the headers that I bought for my engine


http://www.holley.com/6802-1HKR.asp
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  #13  
Old 04-06-2007
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Holy crap those torque monsters are so pretty!!! However, when you flip over that price tag and take a look, it makes me want to puke!! Plus...if those are considered "long tube", that's a pretty short tube!

I'll probably go with a set of FRPP or I'll get mine ceramic coated. Can you ceramic coat a set of cast headers?
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  #14  
Old 04-06-2007
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Do you think it'd be worth the time and effort to remove those emissions bumps in the exhaust ports?
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  #15  
Old 04-07-2007
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my trucks a 91' and the headers that come with the swap are the headmanns...
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  #16  
Old 04-07-2007
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Quote:
Originally Posted by Needforspeed3685
Do you think it'd be worth the time and effort to remove those emissions bumps in the exhaust ports?
YES
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  #17  
Old 06-10-2007
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as far as the GT40ps, well p= piece...they are pretty garbage, i tried em on my truck and it rlly had no more than stock, i put a set of ported and fully rebuilt GT40's from the 93 cobra and made a very noticable difference..

also bout the headers, my truck is one of the early years, 84, but i put on a set of james duff longtubes, and only had to replace motor mount bushing and they just slipped in...drivers side throught the bottom went very easy..as far as the passenger side, like i said through the bottom, different motor mount bushing, and a very slight notch in frame rail, and went in, and even w/ motor shaking, doesnt hit rails...
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Old 06-10-2007
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Quote:
Originally Posted by Speedstang302
also bout the headers, my truck is one of the early years, 84, but i put on a set of james duff longtubes, and only had to replace motor mount bushing and they just slipped in...drivers side throught the bottom went very easy..as far as the passenger side, like i said through the bottom, different motor mount bushing, and a very slight notch in frame rail, and went in, and even w/ motor shaking, doesnt hit rails...
Unfortunately, the situation is very different for 98+ Rangers which have a different frame, suspension, and engine bay layout. There are no commercial long tube headers that will fit. The Torque Monster headers are the best available for 98+.
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Old 06-10-2007
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^ yeah,.. and they know it.. which is why they cost a pretty penny. but they are damn sexy lookn.
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  #20  
Old 09-05-2007
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Quote:
Originally Posted by Speedstang302
as far as the GT40ps, well p= piece...they are pretty garbage
I know this is bringing a thread back from the dead but this guy is way off . . .
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  #21  
Old 09-22-2007
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yeah that dude is stupid i ran 8.50's in the 8th with a set of gt40p on a 302 mustang.
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