GT40 vs. GT40P

bentley429 · May 26, 2005

Can anyone tell me what the difference is between the two and which is better. Iam looking into buying a pair

Car RamRod · May 26, 2005

ssseeeeeaaaaaaaaarrrrrrrrrcccccchhhhhhhh.

i got gt40p's and like them. the only downside is that you need special headers if you want shorties.

Michael Yount · May 26, 2005

Both are cast iron - the 40's came on the Cobra, early Explorer/Mountaineers and the early Lightnings. The 40P's came on the later Explorers/Moutaineers. The P's flow a bit better and have a more efficient combustion chamber design - hence the relocated spark plugs. The plugs cause a lot of folks headaches with headers that aren't designed for them - difficulty changing plugs and burnt boots/wires. Your choice...

bentley429 · May 26, 2005

Car RamRod said:
ssseeeeeaaaaaaaaarrrrrrrrrcccccchhhhhhhh.

i got gt40p's and like them. the only downside is that you need special headers if you want shorties.

I did search and saw some people saying gt40's were better, some saying gt40p's were better. Who makes the headers you are talking about, and why do they need to be different? J/W

dcarlson · May 26, 2005

GT40Ps are more efficient, meaning they use a smaller valve and still manage to flow about the same as a GT-40. The better velocity and revised spark plug position make for a cleaner burn and improved fuel economy. They are also cheap. Overall, they are a great head for performance and daily-driver economy on a budget. However, if all I cared about was power I would go with the original GT-40 heads.

Newer Ford Racing headers are designed to clear the spark plugs on both types of heads.

Car RamRod · May 26, 2005

mac and one other makes the headers. they need to be different to allow for spark plug boot clearance. They are a bit pricey, I think the macs run you 280 or sumthin. Im sellin mine in a month or so.

super302 · May 26, 2005

GT-40's cost more and are worse

GT40p's cost less, flow more, and way easier to find

Guess what ones i have

BTW-there are quite a few people getting 300rwhp from GT40p's....like me for example

Michael Yount · May 26, 2005

Ford Racing shorties accomodate the P spark plug location, are stainless, MUCH higher quality than MACS and cost around $220.

v8only · May 26, 2005

Michael Yount said:
Ford Racing shorties accomodate the P spark plug location, are stainless, MUCH higher quality than MACS and cost around $220.

just bought my ford racing ceramic shorties, $309 to my door via summit, and gt40p compliant. I would have gone stainless, but wanted a finish that would last longer.

check my sig, I think I've got a link for a group of guys doing that 300 rwhp to the wheels with gt40p heads

89MustangGX · May 26, 2005

I dunno -- I think I see alot more GT40's and GT40Ps in classes like NMRA Factory Stock. Must be something to it...

Allforspeed · May 27, 2005

so is there more gt40 headed cars or gt40p headed cars in those super stock classes? i always wondered about this question.............. or maybe more e7te headed cars

Michael Yount · May 27, 2005

v8 only - your FRPP shorties ARE stainless - underneath the ceramic coating. All the FRPP shorties are stainless - you just have a choice as to whether you want them coated or not.

89GX said - "Must be something to it..." Uh, it could have something to do with what heads are legal according to the class rules....the E7's, GT40's and GT40P's all came on factory stock Ford 5.0L engines...

89MustangGX · May 28, 2005

Michael Yount said:
89GX said - "Must be something to it..." Uh, it could have something to do with what heads are legal according to the class rules....the E7's, GT40's and GT40P's all came on factory stock Ford 5.0L engines...

Sorry -- I misspoke. I meant to say I see a lot more GT40 THAN GT40P headed cars.

Highbredcloud · May 28, 2005

Michael Yount said:
v8 only - your FRPP shorties ARE stainless - underneath the ceramic coating. All the FRPP shorties are stainless - you just have a choice as to whether you want them coated or not.

89GX said - "Must be something to it..." Uh, it could have something to do with what heads are legal according to the class rules....the E7's, GT40's and GT40P's all came on factory stock Ford 5.0L engines...

when I was on the market for headers...I was told that you cannot have stainless steel...and ceremic at the same time...due to some sort of chemical change in properties...I'm not big on chemistry so I don't know if that was BS or not...I spoke with some rep at Bassani...

BTW: I have called Ford Racing on many occassions...and even they don't know if the headers are stainless steal under the ceremic coating...I have spoken to 3 different guys there and got 3 different answers...Even though Summit advertises those headers as stainless and ceremic coated...they only provide the discription that was given to them by FMS...

I did a lot of research on this...called many places and nobody could tell me for sure...that's sad...Besides that...nobody knows the guage size on those either...The quality is good though...

89MustangGX · May 28, 2005

Highbredcloud said:
when I was on the market for headers...I was told that you cannot have stainless steel...and ceremic at the same time...due to some sort of chemical change in properties...I'm not big on chemistry so I don't know if that was BS or not...I spoke with some rep at Bassani...

BTW: I have called Ford Racing on many occassions...and even they don't know if the headers are stainless steal under the ceremic coating...I have spoken to 3 different guys there and got 3 different answers...Even though Summit advertises those headers as stainless and ceremic coated...they only provide the discription that was given to them by FMS...

I did a lot of research on this...called many places and nobody could tell me for sure...that's sad...Besides that...nobody knows the guage size on those either...The quality is good though...

I can't say for certain, all I know is what FMS has told me. But since neither of the sets I have had had any JetHot come off (inside or out), I wouldn't worry about that too much.

Highbredcloud · May 28, 2005

89MustangGX said:
I can't say for certain, all I know is what FMS has told me. But since neither of the sets I have had had any JetHot come off (inside or out), I wouldn't worry about that too much.

Yeah...its only one of those what if concerns...BUT even ceremic coating doesn't last forever...If you think about it though...Ford Racing parts are overpriced big time...so if what they claim is true...(stainless steal AND ceremic coated) than its a really good deal on them...BUT the whole point that Ford Racing reps don't know for sure about their product makes me wonder which aftermarket company Ford Racing paid to slap their name on the headers...this makes me mad and sad...at the same time since I am a stickler for Ford Racing products...

Going back to the original posters question...Get whichever you find cheaper...not enough power difference between those two to say which is better...

v8only · May 28, 2005

Highbredcloud said:
Yeah...its only one of those what if concerns...BUT even ceremic coating doesn't last forever...If you think about it though...Ford Racing parts are overpriced big time...so if what they claim is true...(stainless steal AND ceremic coated) than its a really good deal on them...BUT the whole point that Ford Racing reps don't know for sure about their product makes me wonder which aftermarket company Ford Racing paid to slap their name on the headers...this makes me mad and sad...at the same time since I am a stickler for Ford Racing products...

Going back to the original posters question...Get whichever you find cheaper...not enough power difference between those two to say which is better...

I don't find them overpriced at all, in fact, $300 is quite a bargain for what you get, or, conversly, $220ish for stainless is a great deal. From what I understand, you'll pay nearly $300 for a set of mac's that are p compliant, and we all know Mac's are barely worth the money you'd get back from recycling them as scrap metal. The next best thing, jba's are well over $400-600+

04sleeper · May 28, 2005

v8only said:
I don't find them overpriced at all, in fact, $300 is quite a bargain for what you get, or, conversly, $220ish for stainless is a great deal. From what I understand, you'll pay nearly $300 for a set of mac's that are p compliant, and we all know Mac's are barely worth the money you'd get back from recycling them as scrap metal. The next best thing, jba's are well over $400-600+

I agree. Go ahead and price shipping a set of shortie headers to Jet Hot and have them prepped and coated with their "Sterling" finish. It will cost anywhere between $250 and $275 depending on shipping costs. I know I have priced it before.
Plus Jet Hot gives you a lifetime warranty on the headers so I feel it is well worth it.

Don't even get me started with MAC.......

dunnit52 · Jun 3, 2005

Refresh my memory...what is the casting #'s for GT 40 irons???? The P's????

Skoobie · Jun 4, 2005

My car came with GT40's but Im not sure if their P's or not? Easiest way to tell?

GT40 vs. GT40P

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