intake manifold?

[drracing108]

probably a stupid question, but is it not a good thing to use the standard 5tlr efi manifold wen the engine worked? cheers

[b2tf]

yep, no worries at all. if you feel like spending money though, edelbrock and trickflow make manifolds to suit.

[drracing108]

cheers mate

[xr8ute]

depends on what you mean by "worked"...what heads, what cam, and what rpm are you shifting/redlining?

the std intake can support some pretty decent power, but ultimately the long runners hold it back at very high rpm.

the lower needs to be ported to flow as much as the upper, they can flow up to 250cfm with a ported lower (and about ~200cfm stock).

runner length will hurt power above 6000rpm

[drracing108]

so i can get work done to the stock manifold??

[xr8ute]

Yep. The lower intake manifold has runners that taper down in size to be much smaller than even the std GT40P intake ports.

The lower can be ported to allow it to support much better flowing cylinder heads (up to 250cfm).

The only thing that is not so easy to modify is the runner length, so it is not suitable for a combo that wants to make peak power at very high rpm (6000rpm+).

[drracing108]

what would u suggest for decked heads and a fairly big cam??

[xr8ute]

depends on which heads are being "decked" and how "fairly big" the cam is ;)

If you are keeping the std GT40P heads (without any porting), then I would keep the std Explorer intake and not even bother porting the lower...

[drracing108]

yeh we will see, i havent even spoken to the engine builder down south yet, you might know, how much do u rekon it would cost for head work (new heads i guess) big cam and kit and forged pistons and rings? jus a rough estimate....

[mcflux]

how long is a piece of string?

Check out the Windsor section http://fordforums.com.au/forumdisplay.php?f=11 for a heap of info on heads, manifolds, cams, etc...

[Eroda]

what i want to know with ported edelbrock lower, and ported GT40Ps with larger valved etc and a standard au220cam, would i be better running the edelbrock upper ported to 75MM for a 75MM TB or would porting the factory manifold to 75MM and to Match the Lower be just as good

[NeishaXR8_347]

Originally Posted by Eroda

what i want to know with ported edelbrock lower, and ported GT40Ps with larger valved etc and a standard au220cam, would i be better running the edelbrock upper ported to 75MM for a 75MM TB or would porting the factory manifold to 75MM and to Match the Lower be just as good

Thats the weakest link in what you are doing, save the money on the 75mm TB and buy a nice new cam for it. Then it will compliment your bigger valves and head work.

[BLACKAUXR8]

I agree with Neisha. I ported my lower and my standard gt4op heads and it made a huge differance to the low down torque and hi rev power. 70mm TB is more than enough unless your running a big stroker or forced induction.