Porting GT-40P Upper and Lower with a Dremel

MattwantsSpeed · 06-24-2002, 08:32 PM

Does anyone have any input on porting a GT-40P Upper and Lower with a Dremel? Is there anything I should know before getting into it? I'm new to this so any input would be appriciated. If anything I would like to smooth out the ports for less restricted airflow. But I would like to actually make the ports bigger also. I know this will be a slow process, but it's a learning one at that.

Coupe5oh · 06-24-2002, 10:22 PM

You may try and find my old post, some info there, im going to match my stock upper, to a bigger tb, and clean up the upper ports, i have some grinding stones, and abrasive rolls, like sandpaper rolls to do the final cleanup, i was told not to shape the port into a "bell shape"....let me know how it goes, i have my 65mm tb sitting here, just waiting for it to cool donw before i go yank the upper, or i might shove a towel in the upper, and do it on the motor.

good luck...

keakua · 06-24-2002, 10:33 PM

definately wouldn't recommend it. especially trying to make larger ports throughout the intake. unless you have access to a flowbench, there is no way to measure the effects of your cuts and 99% chance that you would probably only result in causing more turbulent airflow into your heads loosing more power then if you had left it alone. I dont think that there's no way you could get enough accuracy to visually grind away with the dremel. porting anything is a science left up to machinist with access to flowbench. thats why companies charge an additional $800 to port heads. what you can do though is port-match your lower intake to the heads. take off the lower, put some layout dye like prussion blue around the head intake ports, then bolt it up without gaskets and let it sit for about 10 minutes. then pull off the lower again and you will be left with a good outline of the intake ports on the head, which should be bigger. grind away on the outside of the head to match the intake port and blend it in the best you can. be carefull not to take off to much, i would grind only up to a couple mm's away from the layout from the dye.

MattwantsSpeed · 06-24-2002, 10:43 PM

I know I'm not pro at it but I atleast want to make the ports smoother. I don't like the way they feel right now. And thank you, I like the idea of port matching like that to the heads. I hadn't thought of that yet.

Mach 1 · 06-25-2002, 04:03 AM

just grind away the casting flash, and use 80 grit, you want it a little rough on a fuel injected upper. The dremel wont be the best tool to use, but might get you started. I did the same thing, and ended up buying a cheap air compressor and a air grinder.

HiFlow5 0 · 06-25-2002, 06:51 AM

Matt, you really don't need to go crazy on those ports! They are pretty big as it is compared to the stock intake. All you want to do is clean up the ports from when the intake was cast. Maybe smooth it out a little bit, but nothing major in the way of porting. You don't need to go crazy like we did on the "other Matt's" Z34. His intake was stock and needed some major reworking to get the ports symmetrical, and the casting cleaned up.

Dark_5.0 · 06-25-2002, 07:23 AM

The intake ports on my stock heads were acyualy bigger than the ports on my GT-40 intake.

06-24-2002, 08:32 PM	#1
MattwantsSpeed Registered Member Join Date: Apr 2002 Location: Lakeland, Fl Posts: 224	Porting GT-40P Upper and Lower with a Dremel Does anyone have any input on porting a GT-40P Upper and Lower with a Dremel? Is there anything I should know before getting into it? I'm new to this so any input would be appriciated. If anything I would like to smooth out the ports for less restricted airflow. But I would like to actually make the ports bigger also. I know this will be a slow process, but it's a learning one at that. __________________ 89 LX Hatch 5.0 5spd, alot of miles, terrible 2.73's, mac cai, pullies, Tri-Ax, 16* timing, elect fan, 3G alt Best to date: 14.331@97.46mph with 14*/stock fan/short belt and a 2.222 60' in 90 degree weather Waiting to put on Off road H and 1 5/8 headers Rice Hater's Club #36

06-24-2002, 10:22 PM	#2
Coupe5oh Registered Member Join Date: Nov 2001 Location: SanAntonio, Tx Posts: 734	You may try and find my old post, some info there, im going to match my stock upper, to a bigger tb, and clean up the upper ports, i have some grinding stones, and abrasive rolls, like sandpaper rolls to do the final cleanup, i was told not to shape the port into a "bell shape"....let me know how it goes, i have my 65mm tb sitting here, just waiting for it to cool donw before i go yank the upper, or i might shove a towel in the upper, and do it on the motor. good luck... __________________ Police package 5spd 90 Lx, Stock original motor, 3.27grs, BM fan, fms 10.5 clutch, D&D quadrant, and adjuster, ADS chip, 180 stat, mac cai, mac h-pipe, mac subframe connectors, ASP crank pulley, ripper shifter, 26x10.5 M/T sport pros welds. 246 hp according to analyzer Race weight: 3,120 E.t-13.57 with 26x10.50's e.t. streets. 1.88 60' mph- 99.92 mph

06-24-2002, 10:43 PM	#4
MattwantsSpeed Registered Member Join Date: Apr 2002 Location: Lakeland, Fl Posts: 224	I know I'm not pro at it but I atleast want to make the ports smoother. I don't like the way they feel right now. And thank you, I like the idea of port matching like that to the heads. I hadn't thought of that yet. __________________ 89 LX Hatch 5.0 5spd, alot of miles, terrible 2.73's, mac cai, pullies, Tri-Ax, 16* timing, elect fan, 3G alt Best to date: 14.331@97.46mph with 14*/stock fan/short belt and a 2.222 60' in 90 degree weather Waiting to put on Off road H and 1 5/8 headers Rice Hater's Club #36

06-25-2002, 04:03 AM	#5
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	just grind away the casting flash, and use 80 grit, you want it a little rough on a fuel injected upper. The dremel wont be the best tool to use, but might get you started. I did the same thing, and ended up buying a cheap air compressor and a air grinder. __________________ 2002 GT 1993 GT (SOLD) '93 Mustang GT RHC member #142

06-25-2002, 06:51 AM	#6
HiFlow5 0 Registered Member Join Date: Mar 2000 Location: Springfield, Ma, usa Posts: 706	Matt, you really don't need to go crazy on those ports! They are pretty big as it is compared to the stock intake. All you want to do is clean up the ports from when the intake was cast. Maybe smooth it out a little bit, but nothing major in the way of porting. You don't need to go crazy like we did on the "other Matt's" Z34. His intake was stock and needed some major reworking to get the ports symmetrical, and the casting cleaned up. __________________ NewEngland Auto www.baystategearheads.com -91 Mustang Coupe, ex 4cyl (sold) -99 F150, 3" lift, 35" Procomps, Magnaflow exhaust

06-24-2002, 10:33 PM	#3
keakua Registered Member Join Date: Jun 2002 Location: phoenix, az Posts: 20	definately wouldn't recommend it. especially trying to make larger ports throughout the intake. unless you have access to a flowbench, there is no way to measure the effects of your cuts and 99% chance that you would probably only result in causing more turbulent airflow into your heads loosing more power then if you had left it alone. I dont think that there's no way you could get enough accuracy to visually grind away with the dremel. porting anything is a science left up to machinist with access to flowbench. thats why companies charge an additional $800 to port heads. what you can do though is port-match your lower intake to the heads. take off the lower, put some layout dye like prussion blue around the head intake ports, then bolt it up without gaskets and let it sit for about 10 minutes. then pull off the lower again and you will be left with a good outline of the intake ports on the head, which should be bigger. grind away on the outside of the head to match the intake port and blend it in the best you can. be carefull not to take off to much, i would grind only up to a couple mm's away from the layout from the dye.

06-25-2002, 07:23 AM	#7
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	The intake ports on my stock heads were acyualy bigger than the ports on my GT-40 intake. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

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