GT-40P Heads and Intake Install

[MadHandle8169]

I am contemplating the GT-40P Heads and Intake Swap.

I know that new headers are needed, so what does everyone suggest since I have a Bassani O/R X Pipe would Long Tubes welded in be best or would shorty or unequal length headers be better? If the answer is Long Tubes welded in how much would a shop charge to cut my X Pipe and weld in the Long Tubes?

The swap can be done without changing the TB and a couple other supporting mods, correct? However, I want get the best gains. But I can drive around like this until I accumulate the necessary funds?

What other parts are needed for the install? Adapter Elbow, Gaskets, etc?

The reason I asked so many questions is because I am pricing everything out first to see if I can afford it. I have about $1000 to work with and don't want to buy nitrous and have to be constantly refilling the bottle. I just want a pretty quick, cheap, reliable street set-up for now like mid 13s. So can heads, intake, LT, TB, Adapter Elbow, and Gaskets be done if I do all the work myself minus the welding of the Long Tubes.

I'm sorry this is so long I just got a lot of questions.

 

[wytstang]

Lt's make more hp through the entire power range than shortys. I'm not too shure what you mean by "weld in long tubes"?? I would do a tb the engine is going to ask for more air so give it to it. I would get the FMS 65mm it will flow enough for what your doing and is the best quilty wise but your stock one will work fine for the time being. You should still be able to use your stock injectors as well if the heads are heavily modified. Pesonally I would change the timing chain since it's right there it will help keep the timing perfect.

 

[95snoozer]

get mac longtubes and a prochamber

and sell your x pipe

 

[94GT40]

I am contemplating the GT-40P Heads and Intake Swap.

I know that new headers are needed, so what does everyone suggest since I have a Bassani O/R X Pipe would Long Tubes welded in be best or would shorty or unequal length headers be better? If the answer is Long Tubes welded in how much would a shop charge to cut my X Pipe and weld in the Long Tubes?

The swap can be done without changing the TB and a couple other supporting mods, correct? However, I want get the best gains. But I can drive around like this until I accumulate the necessary funds?

What other parts are needed for the install? Adapter Elbow, Gaskets, etc?

The reason I asked so many questions is because I am pricing everything out first to see if I can afford it. I have about $1000 to work with and don't want to buy nitrous and have to be constantly refilling the bottle. I just want a pretty quick, cheap, reliable street set-up for now like mid 13s. So can heads, intake, LT, TB, Adapter Elbow, and Gaskets be done if I do all the work myself minus the welding of the Long Tubes.

I'm sorry this is so long I just got a lot of questions.

This is a similar combination to what I'm assembling right now.

As far as headers, I'm going with the MAC ceramic shorties. $289 shipped. In my opinion, they are the going to be an easier install than long tubes and not a big difference in horsepower.

You can wait on the TB for later. I just happened to find a good deal on a 65mm BBK so I already have one. I am adding a larger MAF later.

I am going with the Felpro gaskets for the intake, heads, and headers. [It's been suggested to me not to go with the copper header gasket that comes with the headers] You will also need some bolts for the intake and heads. ARP are the ones I'm buying.

What about rockers? You can reuse the stock ones. I'm looking out for an inexpensive, but quality set of 1.7 rollers. You can always put them on later too.

You are going to be pushing your budget though. I've already spent...

$470 for the new GT-40p heads assembled
$250 for the used Cobra intake
$290 for the headers
$50 for the used throttle body

That's $1060 and I haven't bought gaskets, bolts, MAF or rockers yet. So it's not too bad, but you have to shop around.

By the way everything I've read and everyone who I talked to and is knowlegable about 5.0 Mustangs says that the stock injectors will support over 300 hp. I have invested in a larger Walbro fuel pump though.

 

[MadHandle8169]

What kind of HP numbers would I be looking at and 1/4 times with this set-up?

By complete heads what do you mean should I upgrade the head off the explorer?

 

[94GT40]

What kind of HP numbers would I be looking at and 1/4 times with this set-up?

By complete heads what do you mean should I upgrade the head off the explorer?

I don't know about 1/4 mile times. Ther are a lot of factors in 1/4 mile times... IE: gears, driver, temperature, etc...

I know of a few guys that are putting down over 280 RWHP with similar combos.

The heads I just ordered on Monday are brand new factory Ford castings with a 5 angle valve job, oversize stainless valves 1.94/1.54 and heavy duty springs, all installed for $470 shipped. I've been looking at and researching heads for quite some time and thought these offered the best combination of performance potential and value.

I'm also hoping for an increase in gas milage with these heads, due to the more efficient combustion chambers. My understanding is that the engineers at Ford redesigned these heads for better gas milage and better emissions, and that the increased performance was sort of a nice bonus.

 

[final5-0]

This is a similar combination to what I'm assembling right now.

As far as headers, I'm going with the MAC ceramic shorties. $289 shipped. In my opinion, they are the going to be an easier install than long tubes and not a big difference in horsepower.

You can wait on the TB for later. I just happened to find a good deal on a 65mm BBK so I already have one. I am adding a larger MAF later.

I am going with the Felpro gaskets for the intake, heads, and headers. [It's been suggested to me not to go with the copper header gasket that comes with the headers] You will also need some bolts for the intake and heads. ARP are the ones I'm buying.

What about rockers? You can reuse the stock ones. I'm looking out for an inexpensive, but quality set of 1.7 rollers. You can always put them on later too.

You are going to be pushing your budget though. I've already spent...

$470 for the new GT-40p heads assembled
$250 for the used Cobra intake
$290 for the headers
$50 for the used throttle body

That's $1060 and I haven't bought gaskets, bolts, MAF or rockers yet. So it's not too bad, but you have to shop around.

By the way everything I've read and everyone who I talked to and is knowlegable about 5.0 Mustangs says that the stock injectors will support over 300 hp. I have invested in a larger Walbro fuel pump though.

A couple of different points of view about the above info.

I would say that I found shortys and lt's are not close to each other as far as a difference in performance. The lt's will really promote more tq in the low & mid rpm range and it will be felt in the seat of the pants big time.

As for the stock 19# inj's supporting over 300 HP I'm not comfortable with that info as well. When you see charts, info and the like about what size inj's support what kind of HP, the HP quoted is usually FWHP and most of the time we think in terms of RWHP cause we use dyno results to verify our progress.

300FWHP is only 255RWHP using the basic 15% drive train loss thing.

Think about this ...... Why did Ford put 24's in the Cobra that dyno in the 225 to 245rwhp range when stock?

There is a reason lots of peeps with combos in the 250 to 325RWHP range run 24 & 30# inj's.

Later
Grady

 

[MadHandle8169]

So 24 LB injectors would be another supporting mod that I would need. I want to keep my Bassani X Pipe and since the LongTubes wouldn't fit couldn't something be cut and those 2 pieces welded together?

Also If I didn't buy new rockers I would just put the old stock ones on those heads? So rockers are probably a good idea.

After looking at all the prices I think I am going to be over my budget by a good amount and probably be pretty disappointed. I don't like to usually do things cheap so I think I am going to do it right. I'll do 3.73 Gears, Edelbrock Intake Manifold and a 70mm Throttle Body now. This way I will have most of the supporting mods done and be ready for the heads minus the injectors and MAF(by the way what size should I get?). I'll save up for some good heads like AFR or Edelbrock and maybe catch a good deal from the classifieds or Ebay.

 

[final5-0]

So 24 LB injectors would be another supporting mod that I would need.

Yes on the larger in's cause the heads you talk about in this post flow a good bit more air and are capable of 350 to 375 FWHP with the correct supporting stuff. I'd go 24's and use an afpr to up the pressure or if you go with a custom tune I'd go with 30's.

I want to keep my Bassani X Pipe and since the LongTubes wouldn't fit couldn't something be cut and those 2 pieces welded together?

If you hack up the B x pipe then it has no value. Why not save up for the lt's/mid pipe and then sell the B x pipe to offset the new exhaust stuff?

Also If I didn't buy new rockers I would just put the old stock ones on those heads? So rockers are probably a good idea.

Since you are now talking much better heads I'm gonna tell you to go stud rr's for their better strength & valve adjustment features. The stud rr's do run the price up and beyond ped rr's but IMHO their worth it. Many use the ped rr's with no probs so I'm not gonna say the stud rr's are a must have type thing. You could run your stockers for a while if needed.

After looking at all the prices I think I am going to be over my budget by a good amount and probably be pretty disappointed. I don't like to usually do things cheap so I think I am going to do it right. I'll do 3.73 Gears, Edelbrock Intake Manifold and a 70mm Throttle Body now.

I'd go for the gears without delay before anything else as they give the most gain for the buck spent.

As for the tb it won't give you didley squat at this time and I'd hold off until your combo is moving a good bit of air. Some of the stock stuff can take you pretty far ...... look at my sig for an example.

The intake IMHO is a great gain for the buck spent item and I'd go for it over small stuff like tb, rr's, ignition and the like.

This way I will have most of the supporting mods done and be ready for the heads minus the injectors and MAF(by the way what size should I get?). I'll save up for some good heads like AFR or Edelbrock and maybe catch a good deal from the classifieds or Ebay.

Since you will have your motor down to a heads off condition it would be a breeze to throw a cam in there at that time. It is something for you to consider for sure.

One last thing is don't replace your stock maf with a 19lb caled maf. Its a worthless waste of your money. Wait until your airflow needs are somewhat higher and upgrade the inj's and maf caled to match them all at the same time. If you replaced the stocker with a 19lb caled maf before you needed it, you then gotta sell it or get it recaled for the larger inj's.

Later
Grady

 

[94GT40]

A couple of different points of view about the above info.

I would say that I found shortys and lt's are not close to each other as far as a difference in performance. The lt's will really promote more tq in the low & mid rpm range and it will be felt in the seat of the pants big time.

I don't disagree on this point, but I was under the impression that he was on a fairly tight budget. [$1000] I am concerned about budget and ease of installation both.

As for the stock 19# inj's supporting over 300 HP I'm not comfortable with that info as well. When you see charts, info and the like about what size inj's support what kind of HP, the HP quoted is usually FWHP and most of the time we think in terms of RWHP cause we use dyno results to verify our progress.

300FWHP is only 255RWHP using the basic 15% drive train loss thing.

Think about this ...... Why did Ford put 24's in the Cobra that dyno in the 225 to 245rwhp range when stock?

There is a reason lots of peeps with combos in the 250 to 325RWHP range run 24 & 30# inj's.

Later
Grady

I was refering to the stock injectors supporting over 300 Flywheel horsepower, which I think is all that he will be making with the $1000 he has to spend.

The owner of the local dyno, who has literally hundreds of dyno results as data, was one of the people who suggested that I keep the stock injectors for my combo. I feel very comfortable with his advice, because he is a Mustang guy and carefully studies the dyno data produced at every session. I was going to go with the 24# injectors, and the neccessary calibrated MAF, but he told me that I didn't need it. I guess I'll find out after I get everything installed and see the A/F ratio at the dyno.

I was simply trying offer advice on how to keep his cost within his budget. When he starts adding long tube headers, 24# injectors, new calibrated MAF, etc... he will be *way* over his budget.

I stay with my previous statement. GT-40P heads, stock cam, shorty headers and some kind of low budget used intake can be obtained for less than $1000 and you won't have to use 24# injectors with it, because you will be lucky to be producing more than 300 FWHP.

 

[94GT40]

Think about this ...... Why did Ford put 24's in the Cobra that dyno in the 225 to 245rwhp range when stock?

I have actually given this considerable thought. Why does my completely stock '94 GT dyno at 191rwhp which roughly converts to 220fwhp, but the '94 Cobra with the GT-40 heads, Cobra intake, 1.7 roller rockers, 24# injectors, different computer, etc... only produce 240fwhp? Only a 20hp gain! Maybe on the '94-'95 Cobras, Ford didn't know what the f__k they were doing.

Why are guys running a similar type combo without the 24# injectors able to get over 280rwhp? [GT-40P heads though, instead of the plain GT-40's]

Not trying to be a smart alek here, but I really don't understand.

 

[cavscout371]

$1000 will get you started but the nickel and dime chit will add up quick and I mean very quick. I bought the trickflow kit hoping to get as much as I could in one package and that sent me back 2g's but thats not bad when you look at what it comes with, but all the other factory stuff I want to replace so it will run right has already costed me at least 1200 and I got plenty more to buy like upgrading the ignition and I have to buy a fuel pump not to mention the weakest link theory which is once you add horsepower to your engine everything else has to catch up it sucks.

If you have a grand buy the big stuff and get that out of the way its easier to accumalate 200-300 dollar parts paycheck to paycheck its alot harder to save up for the big stuff well at least thats my $.02

 

[final5-0]

I don't disagree on this point, but I was under the impression that he was on a fairly tight budget. [$1000] I am concerned about budget and ease of installation both.

I was refering to the stock injectors supporting over 300 Flywheel horsepower, which I think is all that he will be making with the $1000 he has to spend.

The owner of the local dyno, who has literally hundreds of dyno results as data, was one of the people who suggested that I keep the stock injectors for my combo. I feel very comfortable with his advice, because he is a Mustang guy and carefully studies the dyno data produced at every session. I was going to go with the 24# injectors, and the neccessary calibrated MAF, but he told me that I didn't need it. I guess I'll find out after I get everything installed and see the A/F ratio at the dyno.

I was simply trying offer advice on how to keep his cost within his budget. When he starts adding long tube headers, 24# injectors, new calibrated MAF, etc... he will be *way* over his budget.

I stay with my previous statement. GT-40P heads, stock cam, shorty headers and some kind of low budget used intake can be obtained for less than $1000 and you won't have to use 24# injectors with it, because you will be lucky to be producing more than 300 FWHP.

Mark

You bring up some very good points and the fact that he is using the stock cam is important to keep in mind. The stock cam will keep the air flow down somewhat, but still IMHO he does have the ability to produce 250 to 275rwhp with those heads and the correct supporting parts so you are gonna be pushing the stock 19's to the limit. I'm just an old school kinda guy and I've seen what not enough fuel is all about and it can get ugly. Bottom line with me is better safe than sorry.

As for his budget I understand all too well but if I have some info that I think would be helpful then I try to share the facts which have nothing to do with budget so the poster can at least have some more info.

We all have to decide where to draw the line on money spent and performance gained. Ain't it a shame thats the case cause if it wasn't, most of us would have quicker cars, lol.

Later
Grady

 

[MadHandle8169]

So basically you guys are saying get the Gears and Intake now and leave everything else alone. Then once I decide or find a great deal on heads do that stuff then? Will the stock TB bolt up to the factory Cold Air Intake?

 

[final5-0]

I have actually given this considerable thought. Why does my completely stock '94 GT dyno at 191rwhp which roughly converts to 220fwhp, but the '94 Cobra with the GT-40 heads, Cobra intake, 1.7 roller rockers, 24# injectors, different computer, etc... only produce 240fwhp? Only a 20hp gain! Maybe on the '94-'95 Cobras, Ford didn't know what the f__k they were doing.

Those Cobra FWHP values are sand bagged values.

Why are guys running a similar type combo without the 24# injectors able to get over 280rwhp? [GT-40P heads though, instead of the plain GT-40's]

Not trying to be a smart alek here, but I really don't understand.

Mark

You'll have no trouble finding lots of peeps running combos that are on the verge of starving for fuel. One reason is they don't have any way to verify their af ratio. Don't tell me about the dyno chart they got showing the ratio cause they upped the pressure to get that af ratio and in a day or two the adaptive strategy in the pcm will have dialed back the fuel cause that is its main function.

Another reason lots of combos run around with too small of an inj is its more costly to go to a larger maf/inj setup.

I would invite you to hang around on some of the self tuner sites to see what some peeps have found out after they got the ability to get some hard facts from their data logs as far as fuel issues like duty cycle, pulse widths, and the like.

You have heard the saying ...... Lean is Mean
On our GT Stangs its more like ...... Lean is Ping

Ever wonder why you don't hear the Cobra boys crying about ping?
The answer is better fuel tables and larger inj's.

I'm done now, lol.

Later
Grady

 

[94GT40]

$1000 will get you started but the nickel and dime chit will add up quick and I mean very quick. I bought the trickflow kit hoping to get as much as I could in one package and that sent me back 2g's but thats not bad when you look at what it comes with, but all the other factory stuff I want to replace so it will run right has already costed me at least 1200 and I got plenty more to buy like upgrading the ignition and I have to buy a fuel pump not to mention the weakest link theory which is once you add horsepower to your engine everything else has to catch up it sucks.

If you have a grand buy the big stuff and get that out of the way its easier to accumalate 200-300 dollar parts paycheck to paycheck its alot harder to save up for the big stuff well at least thats my $.02

This is good advice. This is basically what I'm doing now. All I have left to buy is mainly the nickle and dime stuff.

 

[95snoozer]

just remember, all the stuff for a heads cam swap is 150+ for lube timing chain gaskets and head bolts

stock TB is ok, but i would skimp out on the elbow and do a fox body conversion

 

[94gts]

This is basically what I'm doing now. All I have left to buy is mainly the nickle and dime stuff.

mine are goin on as we speak

 

[94GT40]

mine are goin on as we speak

Can you come over to my house when you're finished? I'll by the beer, you help me install mine...

 

[xkuntrycowboyx]

As far as a cobra goes... i think the 94-95's were crap...especially suspension wise...ford couldn't get them to hook like they did in 98. 98 Cobras were beasts in our body style, and they hooked well with a redesigned suspension!!!