Porting Intake Manifolds - HOW TO and REACTIONS.
Thread Starter
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Joined: Mar 2001
Posts: 171
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From: Twin Cities, MN
Just look at the pics, take about that much off. Yeah it is basically making the holes bigger, but the part near the injectors is the biggest restriction. 
It's really easy, it'd be really hard to accidentally just go through the manifold. Just look at the thinnest part of the manifolds and dont go any thinner than that.
It's really easy, it'd be really hard to accidentally just go through the manifold. Just look at the thinnest part of the manifolds and dont go any thinner than that.
Junior Member
Joined: Jun 2002
Posts: 8
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From: Columbus, Georgia
I have an '86 RX-7 that has been ported and I love it. The only problem I have found is that the revlimiter kicks in well before I hit my new redline (around 8k - 8200). Is there a way to counter act this so I can get the most out of my new port job? Great write up by the way.
Senior Member
Joined: Feb 2001
Posts: 271
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From: NA
FYI, we've been making ported manifolds for Rx7s, MR2s, and supras as a premier item for our shop. It benefits just about any car really. We don't just port though...our hi-flo manifolds are ported, polished, and sandblasted(beaded) for a clean look. We've been tested them on the Rx7s for a while, and the best gains are found on ported motors, obviously. Gains of 6RWHP can be seen on a '86 GXL SP motor...and we even got 13RWHP from a BP motor in a '87 SE. However, the '87 SE had ported/polished lower manifold, TB, and upper manifold...the '86 GXL only had the port/polished upper manifold and bored TB. But yes, the gains are noticeable and work for both NAs and T2s...we don't have numbers on the T2s yet..they'll come shortly...
Last edited by RotaryMan88; Jun 26, 2002 at 08:32 PM.
Full Member
Joined: May 2002
Posts: 117
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From: NW Chicago Area
Hey guys,
I went to home depot and couldnt find that bit. When i described it to an employee and what it was going to be used for, he looked at me like i was an idiot. Who is the manufacturer, the size, and its number?
I went to home depot and couldnt find that bit. When i described it to an employee and what it was going to be used for, he looked at me like i was an idiot. Who is the manufacturer, the size, and its number?
Thread Starter
...
Joined: Mar 2001
Posts: 171
Likes: 0
From: Twin Cities, MN
Originally posted by aZizzo
Hey guys,
I went to home depot and couldnt find that bit. When i described it to an employee and what it was going to be used for, he looked at me like i was an idiot. Who is the manufacturer, the size, and its number?
Hey guys,
I went to home depot and couldnt find that bit. When i described it to an employee and what it was going to be used for, he looked at me like i was an idiot. Who is the manufacturer, the size, and its number?
From home depot's site :
"Brand: Beaver Sawdrill
SKU #388544"
Hope that helps
Full Member
Joined: Jan 2002
Posts: 84
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From: Irvine, California
I found that the bit that is second from the right is great for the initial cuts. Then I fine tuned it with a sanding drum to make it a bit smoother. Be careful tho, that bit will cut way too much if you get too crazy with it. I went through several different bits before I found that one, and it made the project go about 5 times faster.
Senior Member
Joined: Jul 2002
Posts: 315
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From: GA
Does it matter if porting the manifold has to be acurrate all around?
I know porting your engine the ports have to be the same, what would happens if you took to much or to little off would your car still run?
I know porting your engine the ports have to be the same, what would happens if you took to much or to little off would your car still run?
mad scientist
Joined: Feb 2001
Posts: 2,665
Likes: 2
From: Savannah, GA
If you dont do enough porting, you wont realize the full gains. If you do too much, youll make the manifold too thin, and it will crack, if you already didnt go through the alum. But as long as youre not a total jackass, its hard to go through the alum. Just keep an eye on the wall thickness.
mad scientist
Joined: Feb 2001
Posts: 2,665
Likes: 2
From: Savannah, GA
Originally posted by hIGGI
pix from alex
pix from alex
Perfect example of what NOT to do. Those already have a very close clearance, and unless you match port the engine block, youre going to have a ridge, which will hurt airflow. I checked with a micrometer, the stock ports are within .1" of each other, at worst...usually tighter. Porting this part is NOT good for flow.
Full Member
Joined: Jul 2002
Posts: 186
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From: toronto
How much is portin' the intake manifold gonna affect gas mileage? Lots less than porting the engine, I guess. Not that I don't want to go fast, but I don't feel like getting 10 mpg from my '86 for 5 - 10 hp.
mad scientist
Joined: Feb 2001
Posts: 2,665
Likes: 2
From: Savannah, GA
I get from 22 to 26 mpg depending on how I drive. Thats mixed city/highway. My gas mileage actually went up when I ported my manifold, but I dont remember how much. Pineapple sleeves really help too. I have something similar in my car, and I got a 3 mpg increase when I put them in.
Full Member
Joined: Feb 2002
Posts: 111
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From: Albuquerque, NM
Well, I just finished completely porting my manifolds, and I just gotta say one thing.......GAWDAMN my hand is sore as $hit. Of course I am using a crappy bit to do it, but it seems to work, it just takes a while. I will post some pics soon. I cannot wait to get it back together. I gotta go to NAPA first and get some o-rings for my fuel injectors. I tore one up taking it apart. Hopefully I will see some gains. I am completely stock, except for some weight reduction. Oh well I am rambling on. Laterz
1988 GXL
Bone Stock baby
but not for long.....hehehehahahaahaa...cough...cough
This pic isn't a finished port. I would say half way done.
1988 GXL
Bone Stock baby
but not for long.....hehehehahahaahaa...cough...cough
This pic isn't a finished port. I would say half way done.