I was sitting on the couch the other day and I picked up the newest Summit catalog that was sitting on my coffee table. Thumbing through the pages, I stumbled upon the Mustang section. That got me thinking about my 1995 GT sitting in my garage. I haven't touched the car in about 9 months. I once had a goal of 300hp by using largly Ford parts and a few things that came with the car.
So far I have aquired:
GT40 iron heads from an Explorer (I want to get these ported... someday haha)
Explorer upper and lower intake manifold
Trick-Flow Stage 1 camshaft (still in box from previous owner)
MAC shorty headers (installed)
UPR offroad X-pipe (installed)
It seems like all the Mustang sites have people that seem to think that it is possible to hit 300hp with that combo. I'm sceptical though. I've heard that the 94-95 engine computers are notoriously hard to tune and don't respond well to top end mods.
What do you guys think? I have about $600 wrapped up in the parts. I need to either start assembling everything or start preparing to sell the car since I need to move in about 10 months (maybe overseas).
According to the interwebz . . . that combo makes and doesn't make 300hp
I think most of those that aren't making 300hp are running around untuned, even though there are some untuned examples.
I think Aussiesmg 302 is making 300 hp . . . He'll chime in.
My 302 is the same as yours except I'll be using F303 cam (also known to make or not make 300hp with GT40p heads and Exploder intake).
I think Car Craft is your friend. They have a XXX HP for $YYY!!!! cookbook in every issue.
When all is said and done you're creating an Explorer 5.0 with a Stage 1 cam. Yes the intake and GT40s move more air than what your '95 came from the factory with but 300 at the crank is probably a bit optimistic. 275-280ish should be possible with the factory ECU and tune if you step up to 24# injectors, a 70mm throttle body and 75mm mass airflow meter CALIBRATED FOR THE 24# INJECTORS (use a Pro-M, don't even consider the others). Don't get caught up on the HP numbers, it'll pick up enough over where you're at now to feel it with the butt dyno!
Good luck,
Jeff
I've been looking at the same combo in my 95gt. Look in to the difference between the gt40 iron head and the gt40p. I know both came in the explorer, one had smaller combustion chambers. Also, see if you can find them in a U-wrench scrap yard. I have one local that'll sell the heads/intake for less than $100.
pres589
SuperDork
10/27/13 9:15 a.m.
In reply to JKleiner:
The whole "mass airflow meter calibrated for a certain size injector" thing that goes on with these cars seems like such a cludge. Why not go with a Moates Quarterhorse or one of the other options and actually change the tune in the computer using time on a chassis dyno? I agree that a larger throttle body and airflow meter are decent ideas.
There's also a plug & play Megasquirt for these cars now as well, although that is a more costly option than the Quarterhorse, and keeping a factory ECU in command does have some benefits.
pres589 wrote:
In reply to JKleiner:
The whole "mass airflow meter calibrated for a certain size injector" thing that goes on with these cars seems like such a cludge. Why not go with a Moates Quarterhorse or one of the other options and actually change the tune in the computer using time on a chassis dyno? I agree that a larger throttle body and airflow meter are decent ideas.
Not disagreeing with you but as the original poster seems to be doing the upgrades on the cheap a meter with skewed calibration will get him pretty close and won't sacrifice driveability (if as I mentioned he uses a Pro-M and doesn't do something crazy like throw in a set of 30# or larger injectors). The Moates and dyno time don't come inexpensively. The last 10 horsepower that method might gain would be some relatively costly ponies.
mndsm
UltimaDork
10/27/13 12:54 p.m.
Install LQ4, throw nitrous at it? Seems to work for Hot Rod at the price you have lol.
Mine makes 309 at the wheels, if you do anything get aluminum heads.
I have all the above parts and 1.6 roller rockers, Holley systemax II, light flywheel, bbk long tubes, vortex fuel rails.
My goal was to be near 400 flywheel without gaining weight over the original rotary
My engine is a fresh rebuild stock bottom end.
GT40 and GT40P are not the same, and Explorers did not come with a GT40 only the P's.
if you port them, you may hit 300. That is the bottle neck. Honestly, I would spend the 1500 on some AFR's to throw on. My goal on the last 302 I was actually building was 400 at the wheels. That's doable, but tough and keep it streetable. I was in college and poor and ended up having to sell the setup to afford classes again.
Thinkkker wrote:
Explorers did not come with a GT40 only the P's.
Actually Explorer 5.0s used GT40 heads up until the middle of model year 1997 at which time the change to GT40P heads occured.
Jeff
In reply to JKleiner:
Do you know what the difference between the regular iron GT-40 and the "P" variety is?
mblommel wrote:
In reply to JKleiner:
Do you know what the difference between the regular iron GT-40 and the "P" variety is?
Smaller combustion chamber, but only slightly. The main purpose was a redesign of the combustion chamber in which the plug was moved. That is why some older designed headers do not work on GT40P heads. Supposed to help with better swirl in the chamber, gains were minimal. As far as porting goes, I've been told on many occasions that the GT40 heads have more room to port than the GT40P heads.....not sure how much I believe this or if it's people not wanting to to move on.
This is the GT40 chamber, note that the plug comes in at an angle to the valves.
This is the GT40P chamber, note that the plug comes in almost perpendicular to the valves.
Another thing you may or may not know about your 95 Mustang engine is it's performance numbers compared to 93 and down 5.0L. In 93 Ford instituted more accurate measuring methods for HP from the factory (with full exhaust, with all accessories, with all intake plumbing). Though no changes to the engine or surrounding were made, the 93 5.0LHO was only rated at 205hp down from the 225 of 92. The 94-95 continued to be rated with the updated system and was rated at 215hp. Compared to the older HO's, the 94-95 is just a touch better in all stock form (I'm sure a good portion due to tuning) but partially from the lighter hyper pistons and tweaked intake.
I bought the GT40s over the GT40Ps because a few reasons. First, due to the revised combustion chamber of the GT40Ps, most normal headers don't fit due to the angle of the spark plug. You can get them to fit but I felt that it wasn't worth the hassle. Also, the stock valve springs on the GT40Ps are terrible. They won't even support the stock Mustang GT cam. I am trying to do things as simple and inexpensive as possible. Yeah the GT40Ps combustion chamber is slightly smaller than the GT40s but only by a few cc's.
I've heard that you can port more on the GT40s as well but I don't know how true that is.
Internet rule of thumb is anywhere from 20-40 HP can be had by just bolting these on. Coupled with the Trick Flow cam and the Explorer intake, I'm hoping for around 300 HP but if I could get to 280, I'd be happy.
In reply to plance1:
Sorry that last one is a little blurry. Stupid camera phone 
It has a little work done. Mostly drivetrain and suspension stuff. The engine is stock with just a cheap CAI. So far the car has:
- Built 8.8 rearend with FRPP 3.73 gears, 31 spline Track-loc differential with carbon fiber clutch pack (03-04 Cobra spec), 31 spline hardened Yukon axles
- FRPP Aluminum driveshaft
- QA1 Tubular K-member
- Twin piston PBR front brake calipers
- Cheapo drilled/slotted rotors (F&R) PO put these on. I hate them
- MAC shorty headers, UPR offroad X-pipe, SLP loudmouth catback
- It has an adjustable FPR and a gauge but I don't think it has a better fuel pump or bigger injectors
Some stuff I bought but haven't put on yet:
- Maximum Motorsports 4 bolt caster/camber plates
- SPEC Stage 1 clutch kit
- FRPP Iron 50oz flywheel
- New Ford OEM clutch cable
- Fiore firewall clutch cable adjuster and clutch quadrant
- New Ford throwout bearing and roller pilot bearing
- Tokico D-Spec shocks and struts (car has used Lakewood 70/30 drag shocks that PO put on which suck for street use)
I just want to make a good DD/fun driver that runs good and is dependable. I had to fix a lot of the PO's screw ups. The rearend is out of an '87 Thunderbird Turbocoupe. I had about 230,000 miles on it and it was toast. I replaced everything except the housing itself.
Enyar
HalfDork
10/29/13 9:55 a.m.
I think you'll be a little short with that combo if I remember correctly from my Mustang days. If you haven't done it yet, I would recommend some underdrive pulleys, 3.73s and subframe connectors. Those made big differences on my car. Also, search around for weight reduction ideas, there are a ton out there for these cars.
soooo... an otherwise stock explorer is just headers and a cam away from ~85 extra hp?
Thinkkker wrote:
GT40 and GT40P are not the same, and Explorers did not come with a GT40 only the P's.
if you port them, you may hit 300. That is the bottle neck. Honestly, I would spend the 1500 on some AFR's to throw on. My goal on the last 302 I was actually building was 400 at the wheels. That's doable, but tough and keep it streetable. I was in college and poor and ended up having to sell the setup to afford classes again.
I have GT40 non P heads that indeed came from a exploder. They're for sale FYI
stanger_missle wrote: Also, the stock valve springs on the GT40Ps are terrible. They won't even support the stock Mustang GT cam.
They won't? Crap, I better go find the guy I sold my 89 to and tell him that. Despite the fact that I put 20k miles and a bunch of autocross runs, track days, and drag passes on it with that combo. 
belteshazzar wrote:
soooo... an otherwise stock explorer is just headers and a cam away from ~85 extra hp?
That is actually not too far off from fact. The cam is a low RPM torque cam. And the real problem is the act of congress to fit anything resembling an exhaust header into a V8 Exploder.....If memory serves me well, I think the V8 was about 10hp more than the V6. Take a look at the factory manifold compared to an aftermarket improvement....
pres589
SuperDork
10/30/13 7:30 p.m.
I always wondered what a Mustang GT cam in a late Explorer V8 would do when combined with 1.7 to 1 full roller rockers to add a bit more everything at the valve over the stock 1.6's.
In reply to Enyar:
I bought some new FRPP 3.73s when I had the rearend rebuilt. The car also has subframe connectors but they are severly rust damaged (never painted or powdercoated). I'm nervous about putting underdrive pulleys on it, even though its a 130A altenator. The PO also removed about 95% of the asphalt soundproofing, the front swaybar and the "dogbone" from the differential case. He was going to turn it into a drag car but never finished.
Just an FYI when I had my '93 Cobra I had a friend who had one as well. He added Fords GT40X aluminum heads, kept the 1.7 RR's and Cobra cam, ported the intake, added LT headers, a bigger Mass Air but kept the stock 70 MM throttle body. With under drive pulleys and a couple of minor mods he had it dynoed at 275 HP at the rear wheels. He used a pre '93 GT ECU with a calibrated Mass Air meter to work with the 24 lbs Injectors. That dyno HP number would mean at least 320 HP at the flywheel on pump gas!
beans
HalfDork
10/31/13 7:26 p.m.
