gt40 help? intake

bighack02 · Sep 15, 2011

alright guys i have an 89 foxbody that im trying to go back fuel injected i have gt 40 heads and the only thing i have right now is a stock upper and lower can you gasket match the lower intake to the gt40 heads? i need it for my daily driver whats the cons to doing this will it work???

Vinnietbird · Sep 16, 2011

You can port it to match. No problems there. I have to question the effort involved. If you're on a crazy low budget....like I am, look around and find an Explorer intake. They can be found for around a hundred bucks, and are a great deal better than stock. The Explorer intake will flow as well as the Cobra and GT40.

Green 94 5.0 · Sep 16, 2011

Vinnietbird said:
You can port it to match. No problems there. I have to question the effort involved. If you're on a crazy low budget....like I am, look around and find an Explorer intake. They can be found for around a hundred bucks, and are a great deal better than stock. The Explorer intake will flow as well as the Cobra and GT40.

Agreed. The explorer intakes can be found quite cheap and are essentially a gt40/cobra intake with a less good looking upper.

striker911 · Sep 16, 2011

I just put a exploder intake on mine and paid $40 at the junk yard. Man is that beast fast. Couldnt be more happy with it.

Maryland Stang · Sep 17, 2011

bighack02 said:
alright guys i have an 89 foxbody that im trying to go back fuel injected i have gt 40 heads and the only thing i have right now is a stock upper and lower can you gasket match the lower intake to the gt40 heads? i need it for my daily driver whats the cons to doing this will it work???

I wouldn't bother, sans an inspection, it's likely that your gasket matching would actually hurt horsepower.

Right now the ports on the intake are smaller than the ports on the heads. That means that there would still be a straight shot from the intake into the heads without the possibilty of a gasket getting in the way or a mismatch between the heads and the intake.

If you make the ports on the head and intake the same size and shape you have to make sure everything is lined up perfectly when you install everything. Since we know that parts are never milled or manufactured to exacting specifications the chances of 4 ports being misaligned using the gasket matched method are extremely high. You could even run into the possibility of all 8 ports being misaligned.

There is also the issue of killing the reversion even if you do somehow manage to get the ports lined up.

Google "Ed Curtis gasket matching" if you want to read what one of the leaders on 5.0 racing thinks about gasket matching.

Maryland Stang · Sep 17, 2011

There is also the issues of the pushrod pinch and the dog legs on runners 1 and 5. Until you fix both of those issues I wouldn't even attempt to increase flow through the intake ports.

tmoss · Sep 19, 2011

If you port the stock lower HO intake well, the intake will flow right at the same numbers as the GT40 head and the intake will work well for a street engine. Use a stock Felpro intake gasket (MS93334 I think) set that is very close to the size of the head ports and use it as a template on the lower - I have an illustrated instruction on how to port an HO lower in the Tech Doc section here:

EECTuning.org • Index page

tmoss · Sep 19, 2011

Maryland Stang said:
I wouldn't bother, sans an inspection, it's likely that your gasket matching would actually hurt horsepower.

Right now the ports on the intake are smaller than the ports on the heads. That means that there would still be a straight shot from the intake into the heads without the possibilty of a gasket getting in the way or a mismatch between the heads and the intake.

If you make the ports on the head and intake the same size and shape you have to make sure everything is lined up perfectly when you install everything. Since we know that parts are never milled or manufactured to exacting specifications the chances of 4 ports being misaligned using the gasket matched method are extremely high. You could even run into the possibility of all 8 ports being misaligned.

There is also the issue of killing the reversion even if you do somehow manage to get the ports lined up.

Google "Ed Curtis gasket matching" if you want to read what one of the leaders on 5.0 racing thinks about gasket matching.

This is all very unlikely if you use a template that is the same size as the head ports and you use the bolt holes and intake-to-block deck surface to align the template.

David19d · Sep 19, 2011

Id go with the Explorer intake. Only issue there is that your air temp sensor may or may not work. You can either drill the lower like everyone I know or you can drill the upper and flip the sensor. Either way it beats the crap out of an even ported stock lower. You still have to run the stock upper after all.

If you do decide to port the lower dont match the gasket. Leave the port slightly smaller. Every little bit of velocity helps.

Maryland Stang · Sep 19, 2011

tmoss said:
This is all very unlikely if you use a template that is the same size as the head ports and you use the bolt holes and intake-to-block deck surface to align the template.

If one insists upon using a gasket to port (you'd be surprised at how many times a day the tech line at Fel-Pro has to say they're gaskets, not porting templates) I'd do this.

Lightly glue the gaskets exactly where you want them on the head.

Then sit the intake down on the gasket and bring about 10 ft lbs of torque on the bolts.

Then drill a 1/8" hole in each corner of the intake right through the gasket. You only want to knick the head just barely but enough to make a hole in the gasket.

Then remove the intake and gaskets and place the gaskets on the intake and line them up with the holes in the manifold and gasket.

When you're done porting take the gaskets and place them back on the heads using the holes you drilled to put them back exactly where they came from.

Then set the intake back on and line it up with the holes in the gaskets.

I know of no other way to get the precision you need for this type of porting to not hurt horsepower.

tmoss · Sep 19, 2011

I've seen that methodd posted elswhere before - there are other ways of doing it accurately that are not as involved as pinning the gasket. Consider that placement is controlled by the bolt holes, front to back and top to bottom.

Maryland Stang · Sep 20, 2011

tmoss said:
I've seen that methodd posted elswhere before - there are other ways of doing it accurately that are not as involved as pinning the gasket. Consider that placement is controlled by the bolt holes, front to back and top to bottom.

There's too much slop in the intake bolt holes to get it right consistantly. People have been complaining forever that the gasket slipped and blocked the ports. That's why I used a FelPro 1262S on my intake. The port openings are so big that even if the gasket slipped it still wouldn't cover the ports.

tmoss · Sep 20, 2011

Maryland Stang said:
There's too much slop in the intake bolt holes to get it right consistantly.

I don't seem to have any trouble at all - about 750 times on Fords so far.

gt40 help? intake

bighack02

New Member

Vinnietbird

Member

Green 94 5.0

striker911

Member

Maryland Stang

Active Member

Maryland Stang

Active Member

tmoss

Gettin Wired

tmoss

Gettin Wired

David19d

New Member

Maryland Stang

Active Member

tmoss

Gettin Wired

Maryland Stang

Active Member

tmoss

Gettin Wired

Similar threads

gt40 help? intake

New Member

Member

Member

Active Member

Active Member

Gettin Wired

Gettin Wired

New Member

Active Member

Gettin Wired

Active Member

Gettin Wired

Similar threads

Privacy & Transparency

Privacy & Transparency