I'm thinking of upgrading my heads this summer and getting a cam and I was wondering how much better the p's were than the regular gt-40 heads.
How much better are the gt-40p than the gt-40 heads?
- Thread starter bjl95mustang
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I've always considered the P heads to be better, however when you look at the F/S class in the NMRA the top 5.0 guys are running regular GT-40 heads.
Each have their own benefits. To determine which is best, you would need to be more specific about what you want from the car, how much money you are willing to spend, and what needs to remain legal about the car and what you are looking for from the car.
Joe
Each have their own benefits. To determine which is best, you would need to be more specific about what you want from the car, how much money you are willing to spend, and what needs to remain legal about the car and what you are looking for from the car.
Joe
timk
Founding Member
well, they may not be better.
P's:
1. have a smaller combustion chamber.
2. have better low-lift flow numbers.
3. flow numbers level at .500 lift.
4. need different headers. long tubes are usually ok, but lots of shorties have trouble with plug and plug wire interference.
5. you need to use different plugs than any other 5.0 head.
6. offer pretty good milage numbers...mine went up quite a bit versus my ported E7's. no doubt, they were designed with milage/efficiency/emissions in mind for the explorer.
7. they're cheap, and easier to find used than standard gt-40's, since they were used on v8 explorers from 97 on up.
8. are not drilled for your smog pump air tubes...if you have to pass a rigorous visual test, you'll have to rig the air tube.
gt-40's:
1. the gt-40's have larger combustion chambers.
2. the gt-40's flow pretty well past .500
3. normal headers and all of the spark plugs you know and love work with them.
4. porting experts know a lot about regular gt-40's.
5. a bit rare, and consequently worth more when you are done with them.
6. totally emissions legal.
all that being said, porting either (as long as the porting is done by someone who knows the ins and outs of the P's) can yeild some pretty good power.
i hope that helps.
P's:
1. have a smaller combustion chamber.
2. have better low-lift flow numbers.
3. flow numbers level at .500 lift.
4. need different headers. long tubes are usually ok, but lots of shorties have trouble with plug and plug wire interference.
5. you need to use different plugs than any other 5.0 head.
6. offer pretty good milage numbers...mine went up quite a bit versus my ported E7's. no doubt, they were designed with milage/efficiency/emissions in mind for the explorer.
7. they're cheap, and easier to find used than standard gt-40's, since they were used on v8 explorers from 97 on up.
8. are not drilled for your smog pump air tubes...if you have to pass a rigorous visual test, you'll have to rig the air tube.
gt-40's:
1. the gt-40's have larger combustion chambers.
2. the gt-40's flow pretty well past .500
3. normal headers and all of the spark plugs you know and love work with them.
4. porting experts know a lot about regular gt-40's.
5. a bit rare, and consequently worth more when you are done with them.
6. totally emissions legal.
all that being said, porting either (as long as the porting is done by someone who knows the ins and outs of the P's) can yeild some pretty good power.
i hope that helps.
Thanks for the info. I have seen used gt-40 going for about $250-300 a pair. Is that a pretty good deal?
A few things mentioned in the above post...
In fact, their chamber is larger than most aftermarket cylinder heads.
It basically comes down to this: If you are willing to change the cam, I'd go with the P heads. If you have the means, have them decked and have the exhaust valves backcut. If you are keeping the stock cam, go with the GT40s. The stock cam works better with the flow rates and ratios of the regular GT40 head.
Nothing I said was meant to be a slam against anyone.
Joe
Than what? Surely not the E7's.
In fact, their chamber is larger than most aftermarket cylinder heads.
You need to use a different plug compared to the other STANDARD 5.0 heads.
If they aren't drilled for smog, how do they pass emissions? My car ran squeaky clean through a rather tough emissions program.
This one fried me the most. If your head guy knows about a regular GT40, and not a P head, he should be avoided at all costs. It just so happens that because of the valve sizes, and intake and exhaust runner ratio, the ports can be opened up evenly where as the P's need much more exhaust work done to them. An "expert" would know about all heads and would take into consideration a multitude of things before he began his work.
It basically comes down to this: If you are willing to change the cam, I'd go with the P heads. If you have the means, have them decked and have the exhaust valves backcut. If you are keeping the stock cam, go with the GT40s. The stock cam works better with the flow rates and ratios of the regular GT40 head.
Nothing I said was meant to be a slam against anyone.
Joe
timk
Founding Member
he was comparing gt-40's with p's. so was i, soooooo...............
p's have a smaller combustion chamber than gt-40's. 61cc vs. 65.5cc.
VISUALLY, the p's have a hard time passing. you have to rig the air tube. emissions-wise, you don't need a smog pump to pass a sniffer test. the run very clean, as stated.
i'm not a porting expert, but i have heard and read much discussion regarding how to best port the p's, and there are lots of differing opinions.
i'm just trying not to sound like an idiot............
p's have a smaller combustion chamber than gt-40's. 61cc vs. 65.5cc.
VISUALLY, the p's have a hard time passing. you have to rig the air tube. emissions-wise, you don't need a smog pump to pass a sniffer test. the run very clean, as stated.
i'm not a porting expert, but i have heard and read much discussion regarding how to best port the p's, and there are lots of differing opinions.
i'm just trying not to sound like an idiot............
