GT40P Heads

[loyd]

Am I waisting my time by putting in a X-303 w gt40p heads? Have around 10:1 compression, just not happy with the E-303 cam.
Was told gt40p heads don't flow very well. If so what heads other than the twisted wedge heads are any good?

Thanks for your help.

[Timido]

Why is it a turd? You can make more with better heads but it should make decent power with the gt40p's What are your Goals?

[loyd]

14's it's a turd!!

I'm making changes and the X cam and pistons is some of the changes, just don't seem to have it on top end. I figured it should be in the mid to low 13's the way it is.
Maybe I'm expecting to much. Just thought heads might help it some more.

[331TwistedWedge]

first off, i would take the gt40p heads all day long over a set of trick flow twisted wedge heads ... (if you're running a 302/306)... i think the trick flow heads are too BIG on 302's ... the 170cc intake runner is more like a 185cc ... its a 1/4" shorter radius to the valve, so they are bigger than advertised ...

there are a few people on the board running 11.70's-11.80's with the gt40 or gt40p's ... seems like the trick flow stage 1 cam is putting down some decent numbers matched with the gt40p's ... if you're on a budget, go with a stock cam and 1.72 rockers ... although the tf stage 1 cam is less than $200 ...

im porting a set right now for shawn (95redstang), they are an excellent casting ... straight to the valve intake runners ... i can see why the explorer/mountaineer combo is strong ...

its funny how the $2500 trick flow upper end package has shown to dyno 275-300 to the wheels ... ive seen gt40p and gt40 combos crush those numbers ...

hope this helps ...

[331TwistedWedge]

did you upgrade your valve springs on the p-heads? ... that e-cam isnt hurting you, its actually a "decent" choice ... wouldnt be my first choice, but its not all that bad ...

[loyd]

Yes springs are upgraded, just want to run a respectful number, and would like to try the X-303 cam with the new pistons. Maybe I just need a TFS stage 1 camshaft.

[93snake]

Loyd, did you just bolt and go with the p heads? I agree that you should have changed valve spring. you said 14's but what mph?

[loyd]

97 mph

Heads was new with upgraded springs

[93snake]

only 97mph... my 93 cobra runs 100mph in stock trim (its gt40's and cobra intake but not that different from your setup) as for et, are you running soft compound tires?

[loyd]

et streets thats why I say its a TURD

[93snake]

can I ask, how hard you leaving?

[loyd]

4000 any less it falls on it's face with sticky tires
shift points have been changed and the best is about 4800
timing has been changed from 8-16 no changes
3 ecu's no change

[93snake]

alright, I agree it sounds like its down on power... I dont have a gear or soft tires on my cobra... is that the same short block that was in the car when you got it? just wonder if it might be on the worn side

[loyd]

yes it is but I'm doing a different one the compression is more that's why I was wanting to run the X cam, pistons are getting fly cut, just was wondering if these heads are worth messing with.

[93snake]

I dont think the p's will be enough head for the x-cam, have not ran an x-cam with a set of gts but the heads always seemed to work better with small cams for me

[loyd]

so you say TFS stage 1 also?

[331TwistedWedge]

that x-cam is too big for the p-heads ... isnt that x-cam like a .542 lift ... these heads dont flow much over a .500 lift ... keep it small ... opt for that tf st 1 cam ...

not sure why you're down on power ... i figured it should trap 107-108 minimum ... have you had it dyno'd? ... you may need a simple tune, looks like you're running a sn95 car ... finicky computers ...

[loyd]

SN-95 is my driver
No tune or dyno to embarrassed on the fox body

[331TwistedWedge]

SN-95 is my driver
No tune or dyno to embarrassed

Lol ... it cant be that bad ...

what intake are you running?

[loyd]

gt40 expolrer, 24# inj.,

[331TwistedWedge]

we need shannon to chime in ... he made 325 hp with that set up ... he's smarter than your average bear though ...

[93snake]

if you looking for more topend, I would think a F cam over a stage-1

[loyd]

Just would like to run bottom 13's maybe 12's

[5.0calypso93lx]

Next thing I would do is get a good tune put on the car.

[331TwistedWedge]

Just would like to run bottom 13's maybe 12's

go down to cincy speed or go see ken at md ... do a few pulls and see where your at before switching things ... you should be in the 260-270 area ... hell maybe more ... if so, thats your 12's that you want ...

an hour of dyno time is cheaper than a cam swap ...

[Timido]

I would dyno the car also. You said you have upgraded valve springs. See if you can find a compression tester and leakdown tester. My first thought was valve springs or valve lash/rocker adjustment or valve timing. My old P head combo ran 12.40 on Drag radials at 3450lbs No port work stock cam. It was a blast to drive on the street.

[kennebellcobra]

I second the dyno to see whats going on...if your shifting at 4800 to run your best et something is definalty off!

[NO SHOT]

I've owned somewhere around 200 mustangs in my lifetime,and it has been my experience that gt-40p heads are junk.Now I know that there are a couple of guys on here that have gt40p heads and intakes and their cars run 11's and they make more power than everyone elses 347 strokers with good intakes, good aluminm heads,and good cams.
You should shift your car at lest 5500. But I'd sell those heads and buy some afr's. and I agree with the E303 being junk I'd rather have a stock cam. If you have access to the X30 i'd use it

[loyd]

Ok so I'm going to do a compression test then a leak down test.

Just want to know on this motor I'm building with the X-303 cam if I need different heads? So far noshot said what I was thinking. I'm building a new motor more compression still 5.0 (302) just looking for help on info, I know there's something wrong with the motor I have now!

Thanks everyone that has helped!
Still need more info and idea's.

[Timido]

If I was going to spend the money on building a new motor you might as well build a bigger one.

[loyd]

Still on a budget!! Yes I would love to have a 347!!

Thanks

[Jeff88coupe]

Yep..if your building a new motor...definatly think about building a 331/347. The cast crank kits are not much more than building a decent 306. A stock set of gt40/p's will support enough power to run mid 12's. I use to run a set of ported gt40p's on a stock 302 shortblock back in '01. Ran a best of 12.19 at 110....10.98 at 126 on a 200 shot.

[12seclx]

I don't know if the gt40p heads are junk or not but I really like them....

I've been really fortunate to take my blown 331 engine saga and turn it into something great....

I had reached a point with the car that found me "burnt" out.... I was done sinking money into an engine... my quest led me to a junkyard for a 99' Mountaineer engine....

My heads have never been lifted... just a drop-in replacement Comp beehive spring kit accompanied by Scorpion 1.72 rockers... stock speed density camshaft...

Last time on the dyno it made 296hp, 3,120 lbs.... and I've made 20 passes in the 11's to date... Last time out it went 11.80 @ 113.63mph... 11.84, 11.87, 11.91, 11.98 @ 96mph....(lifted to ensure a win in bracket racing)....
The car sixty foots in the 1.55-1.58 range....

I've probably made 40-50 pulls on the dyno... in 2007, I ran 12.13 @ 110.57mph with the stock valvesprings and stock rocker arms... If I drive it like I'm sane, it'll get 22-24mpg....

It's not neccessarily the heads fault if the car doesn't run a number... I refuse to open up my motor til' I've done all the other little tricks and feel like I've reached a wall..(which is gettin' close). I think it will go a 11.75-11.79 but it's gonna take some really good air and a hookin' track...

if you want any of the details on my set-up, pm me your email address....

[NO SHOT]

I wasn't saying buy a 347. I would rather have a 302 myself. I was just saying most gt40p applications run mid to high 12's but some guys cars on here are much faster than can cars with nice cams and aluminum heads

[loyd]

I didn't say anything about a 347 to you.

I'm just trying to get some info on some builds with a 5.0 (302) not a stroker, not blown just N.A. Fuel injected and using a X-303 cam and P heads, so I no now not to use a x-303 camshaft cause there has been nothing said good about it.

So TFS stage 1 cam, p heads will run good enough for what I want? The E-303 cam that bad?

Thanks for everyone's input this has helped me a lot!

PS anyone want to buy a X-303 or a E-303? LMAO!!!

[kennebellcobra]

I have the regular 40's that I ported with the tf stage 1, explorer intake on a 302 and put down 325 and went 11.74 in a almost 3300 lb car...the p's and 40's are similar so it should make power but running the et takes a lot more than just power. I think you might just have some other issues going on to only trap 97...my e7's and others have gone 104-105.

[loyd]

I agree with something going on, that's why I'm building another engine and thought that the X-303 would be a alright cam to run and get more top end power. I've tried different ecu's, distributor, fuel pump, mass air flow meter and housing. I think she's wore out. So the P heads are fine? I'm going to replace the springs just in case. Where would be a good place to take the heads for some port work? Or is it worth it? Just want some info. Bye the way compression is 135-150 no leak down on the 135 #4 cyl.

[Timido]

The compression sounds reasonable. Check your valve springs and valve lash. You are on the right track.

[331TwistedWedge]

you need to listen to (kennebellcobra, 12seclx, timido and jeff88coupe) these guys have ran or are running that combo ... all 4 of them went 11's ... this combo works ... dont waste your $$$$$$$$$

im building and slowly researching a few things myself for this combo ... its going in a 3850 lb 1995 convertible mustang :lol: (95redstang's car) ... were hoping 280 to the wheels ... p heads (blended/valve spring upgrade), tf stage 1 cam (they r cheap) and a mountaineer intake ...

[Timido]

There are many different ways to skin a cat. No one person is right and no one person is wrong. That is why they make blowers, Tuirbos, Nitrous, Small blocks, Big Blocks More blowers, Intercoolers, Different heads/intakes cams/ Pistons and who knows what else..... The basic concept is the same there are many different paths to get to where you are going.