Fox Gt40 Head Porting And Build Question?

91gte303 · Jan 22, 2016

Hey yall, I've been playing with my heads at work on my lunch hour and did a little clean up. I was wondering what yall think and what you guys might add to it?

Didn't want to get too far without asking. also, the port, I have smoothed out the casting flash on both the intake and exhaust

91gte303 · Jan 22, 2016

for some reason, my phone uploaded two of the same pictures and none of the others when it charges, I will try again.

91gte303 · Jan 22, 2016

basically, the heads are the F3ZE gt40s. I cc'ed them at 62.5CC's jicyw. im gonna mill .015 off them. was gonna go .030" off, but was worried about intake alignment issues. would that be an issue at .030"?
anyway, the block has been zero decked and im usung a stock '91 bottom end. gonna use .039 head gaskets. so, it should be at 9.5:1. if I mill .030" off, it will be 9.7:1.

gonna be using the n41 cam, upgraded springs, gt40 upper and lower, 24lb injectors, 65mm TB, 76MM mass air housing, long tubes, O/R H-pipe, 2.5" exhaust out to 10 series dumps.
ZT5, ram clutch, hurts shifter, 3.73's and a set of 9" slicks.also have full subframe connectors welded in. car weights in at 2800 without me and 3020lbs with me in it and a half tank of 112.
how do yall think it will run?

a91what · Jan 22, 2016

Open the mouth of the bowl to runner.
Focus on the short turn radius.
Don't touch the floor of the runner except to gasket match, all your focus should be on the roof and walls of the port. I can attest to the fact the bowl to runner can be opened up to a 1.6 valve.

91gte303 · Jan 22, 2016

Here is a view of the exhaust side.. im not quite done with it. I just didn't know how far I could go before I rendered my heads a boat anchor

91gte303 · Jan 22, 2016

Before shot on both

91gte303 · Jan 22, 2016

Exhaust runner

a91what · Jan 22, 2016

You can smooth the thermacitor bump out, smooth the roof of the bowl to runner and open the bowl on the pinched side.

I just looked thru years of my threads to find pics of when I ported my heads.... no go. Lol I would give you picks of mine but they are on the car.

91gte303 · Jan 22, 2016

cool man. how much of an improvement do you think I have made and lastly, how far can I go before I bust into a water jacket?

91gte303 · Jan 22, 2016

also, do you think I can better a 12.50, provided a good launch? figured id launch at about 4K and shift at about 57-6000rpms.

a91what · Jan 22, 2016

As far as improvement, some....
Open up the bowl to runner, then gasket match the runner. Then blend the gasket match to the bowl, taking out the hard edges and smoothing the transition will net more than you think..

Hard to say, I'll let @84Ttop make then et guesses

RangerJoe · Jan 22, 2016

Car is fairly light, I think sub 12.50 is possible with a 1.6 or better 60ft. A lower gear will definitely help more.

Joe

91gte303 · Jan 22, 2016

i was thinking about throwing in a set of 4.10s. I don't think ill go much more because I plan on road tripping and daily driving this car, like before. please don't bash me for that. everybody around here has a jacked up truck and loud exhaust. most think their is fast. hell, I got a Silverado with a good few upgrades...I just want to be different.

a91what · Jan 22, 2016

No bashing here bud. I would only go as high as 3.73 if you plan to do any street driving. 410s are a bit much for a DD just my .02

91gte303 · Jan 22, 2016

yeah, I already got 3.73's in it. it is still bearable on I-95 at 80-90mph. some say yes some say no to the 4.10s. ill just save my money and put it elsewhere. thanks for that.
im planning on a 125 shot to get into the 11's. but, depending on how low in the 12's I get, I might just go without it and use that extra room for the 2 sundown 8's and the box im building for it.
btw, the battery is already been moved to the hatch. I AM thinking of tryin to find an A/C setup and throw it on the car. but that's pretty far down the road.the head DOES work tho.lol

hoopty5.0 · Jan 23, 2016

I have 40+ Hours in my GT-40 heads right now. Other things to do that were not mentioned yet are smooth the curve on the wall of the intake port but be careful of breaking through to the pushrod hole. Smooth the transition from The valve seat into the chamber and polish the chamber. Knock down any sharp edges.

As mentioned before, knock down the EGR bump, but be VERY careful how much you take out as there is a water jacket underneath. I have a ton of helpful pics and links I will post when I get to my computer

hoopty5.0 · Jan 23, 2016

When I initially started, I got greedy on an exhaust port when I was knocking down a valve guide and hit water. But, since the head was junk, I decided to cut it into cross sections and use it as a learning tool. Here are some pics of the short sides of intake and exhaust runners.

Here, you can see where I smoothed the rough edges around the valve seats and polished the chambers some, knock down the rough edges around the spark plug boss.

Also, here are some helpful links:
http://www.diyporting.com/gtpin.html
http://www.diyporting.com/gtpex.html

This one is especially helpful. Download the porting principles file and memorize it. ***THIS IS PROBABLY THE MOST USEFUL INFORMATION IN THIS POST IN THE LINK BELOW***
http://tmoss.efidynotuning.com/

Hope this helps some.

hoopty5.0 · Jan 23, 2016

Here's a link to a thread I started on another forum. Lots of good input from others in here:
http://forums.corral.net/forums/5-0...1-learning-port-heads-what-happened-here.html

This guy did AMAZING things with GT-40 heads.
http://forums.corral.net/forums/5-0-5-8-engine-tech/1093086-another-300-gt-40-dyno-pull.html

http://forums.corral.net/forums/5-0...iron-gt-40s-flowed-today-156cc-240-184-a.html

Here's another good read:
http://forums.corral.net/forums/5-0-5-8-engine-tech/2154218-gt40p-build-dyno-sheets.html

I spent probably 2 weeks reading and researching, collecting pics and asking questions before I starting grinding. I hope you do the same because it sucks doing so much work and not having it work right. It also sucks breaking through and having to start over.

hoopty5.0 · Jan 23, 2016

One last thing @91gte303 The N41 is a good cam to go with, but look up what the spring rates are and make sure you have the right pressures. Just trying to help you avoid mistakes I've already made.

A5literMan · Jan 23, 2016

And as far as your performance goal of sub 12.50's goes...you should be able to do that. Depending on track,altitude,your driving skills,and how well your port job goes, I would think you could see low 12's. If you are going to spray it I would think a low 11 to possibly a high 10(probably need a 150 shot for 10's).

Fox Gt40 Head Porting And Build Question?

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I leave the horn on while driving

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mechanicus terribilis

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At least it is lumpy...

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