Polishing intake runners

JustJeff · 11-11-2010, 10:43 PM

I'm curious what people think about polishing intakes?

I'm specifically interested in polishing the intake runners on the irons, but also interested about polishing the runners on the LIM and UIM.

I'm in the middle of a rebuild on a JDM S5 13B that is mostly stock. I'm not doing any porting of irons or housings. I had a friend suggest I polish the intake runners on my irons, but to me it seems like the benefits from that would be minimal at best.

I suppose all things being equal polishing wont hurt anything. But I'm all out of those types of bits for my dremel and don't want to spend $40 on bits for little or no gain.

***TitaniumTT*** · 11-11-2010, 11:50 PM

You don't want to polish the runners at all. Clean them up sure, but I wouldn't go any finer than a 220 sanding wheel.

What should benefit you more than polishing the runners is portmatching EVERYTHING. Elbow to TB, TB to UIM, UIM to LIM, LIM to block.

JustJeff · 11-12-2010, 12:12 AM

^ Got any links. I understand the idea of port matching but not the procedure.

sen2two · 11-12-2010, 09:05 AM

Dealing with port matching, porting, shaping, polishing, ect. can be VERY trick.

Paul Yaw did a test on a 12a with a flow bench. One port matched, one stock. The stock one produced better flow and power. And he knows what he's doing. Not guess work.

It's a hit or miss without a dyno or a flow bench. But in saying that, I always port, shape, and mess with my intake manifolds, TB's, ect. If it works cool, if not, I'm not trying to set records... so no big deal.

***TitaniumTT*** · 11-12-2010, 10:05 AM

You are correct, if you're not testing you're guessing and I did read that "blog" by Paul. However, it has been documented that there are gains to be had on the RE mani with port-matching and honing... so I did it damnit.

sen2two · 11-12-2010, 12:19 PM

There are plenty of designs online to build a home made flow bench on the cheap. I'm just wondering if its worth the space it will take up if your just doing it for fun. Now if I was competing or trying to break records, I would build one and test my manifolds before I did anything else...

***TitaniumTT*** · 11-12-2010, 04:10 PM

Links? I've got a spare set of mani's that are bone stock right now that I wouldn't mind testing before and after...

sen2two · 11-12-2010, 05:04 PM

Did a quick google search and came up with this... I'm sure there's a ton of info here. A bunch of links came up when i searched diy flow bench.

http://www.tractorsport.com/cgi-bin/.../ikonboard.cgi

NoDOHC · 11-14-2010, 09:38 AM

What is inportant is that the intake runners do not change in cross-sectional area throughout the entire length of the runner. This way the air can maintain a constant velocity. The runner should be slightly larger than the intake port, so that the air is accelerated through the port, resulting in better fuel mix.

I polished my intake runners to 600 grit where dry and 160 grit where wet (after the injectors). If you polish the runner too much where they are wet, you will see a symptom called fuel pooling, which is the fuel forming rivulets on the polished surface. Fuel pooling will make the engine idle very poorly.

160 grit seems to have a small problem with fuel pooling, but nothing next to 600 grit.

My engine will occasionally misfire at low fuel and air flow rates (idle, lightly loaded cruising), but the misfiring is infrequent and barely noticable.

If I were you, I would probably not go past 80 grit past the injectors if you want a good idle.

If you follow the rules of intake porting, there are major gains to be had from it.

EDIT: Here is a thread where this was discussed.
http://www.rotarycarclub.com/rotary_...ead.php?t=8550

JustJeff · 11-14-2010, 11:21 AM

Thanks for the link I'll read it later tonight

What I have read so far about port matching is regarding piston engines. I'm sure it's the same idea but the lip created by variance between where two runners meet encourages the fuel to start coming out of suspension from the air. In other words the fuel starts sticking to walls of the runner at those points.

What I don't understand yet is how you determine which lips/contact surfaces need matched. Or for that matter how much they are off from each other. With piston engines they talk about simply using a marker through cylinder heads and such.

What I'm assuming I could do is use a light coat of paint or ink, simply bolt the parts together and then pull them apart. But that seems awfully prone to fucking it up. Seems like the amounts they will be off will me millimeters and any wiggle or smudging of the paint/ink will throw the whole measurement off.

I'll be doing engine work today between football games and I'll look over the parts. Hopefully having parts in hand I can figure out answers to my questions.

vex · 11-14-2010, 11:47 AM

Most people port match to the gaskets. Just sayin'

RETed · 11-14-2010, 11:58 AM

Yep, use the stock gaskets.
It's the "easiest" method.
Just port both sides to match the gasket dimensions.

-Ted

JustJeff · 11-14-2010, 12:10 PM

That sounds awfully prone to simply making them wider but not matched much better than the factory did. I'd think having them widen and then constrict back down would equally help pull the fuel out of suspension just as much as an uneven lip. Like NoDOHC posted. Hhmmm but perhaps allow the air to flow "better".

I'll read what NoDOHC linked after lunch and some football.

RETed · 11-15-2010, 03:35 AM

Quote:

Originally Posted by JustJeff

That sounds awfully prone to simply making them wider but not matched much better than the factory did. I'd think having them widen and then constrict back down would equally help pull the fuel out of suspension just as much as an uneven lip. Like NoDOHC posted. Hhmmm but perhaps allow the air to flow "better".

I think, at this point, that you're over-thinking the whole thing.
The stock intake manifold system SUCKS.
Any mods to help flow will get you gains.

-Ted

JustJeff · 11-15-2010, 08:04 PM

Quote:

Originally Posted by RETed

I think, at this point, that you're over-thinking the whole thing.
The stock intake manifold system SUCKS.
Any mods to help flow will get you gains.

-Ted

Definitely true about over thinking. In one of my threads I posted that I'm disturbingly perfectionist and I loose sleep over tiny details. Perfect example right here.

11-11-2010, 10:43 PM	#1
JustJeff RCC Contributor Join Date: Mar 2008 Posts: 505 Rep Power: 18	Polishing intake runners I'm curious what people think about polishing intakes? I'm specifically interested in polishing the intake runners on the irons, but also interested about polishing the runners on the LIM and UIM. I'm in the middle of a rebuild on a JDM S5 13B that is mostly stock. I'm not doing any porting of irons or housings. I had a friend suggest I polish the intake runners on my irons, but to me it seems like the benefits from that would be minimal at best. I suppose all things being equal polishing wont hurt anything. But I'm all out of those types of bits for my dremel and don't want to spend $40 on bits for little or no gain.

11-11-2010, 11:50 PM	#2
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son Posts: 4,581 Rep Power: 10	You don't want to polish the runners at all. Clean them up sure, but I wouldn't go any finer than a 220 sanding wheel. What should benefit you more than polishing the runners is portmatching EVERYTHING. Elbow to TB, TB to UIM, UIM to LIM, LIM to block. __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

11-12-2010, 09:05 AM	#4
sen2two KTEC Join Date: Jan 2009 Posts: 642 Rep Power: 0	Dealing with port matching, porting, shaping, polishing, ect. can be VERY trick. Paul Yaw did a test on a 12a with a flow bench. One port matched, one stock. The stock one produced better flow and power. And he knows what he's doing. Not guess work. It's a hit or miss without a dyno or a flow bench. But in saying that, I always port, shape, and mess with my intake manifolds, TB's, ect. If it works cool, if not, I'm not trying to set records... so no big deal. __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

11-12-2010, 10:05 AM	#5
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son Posts: 4,581 Rep Power: 10	You are correct, if you're not testing you're guessing and I did read that "blog" by Paul. However, it has been documented that there are gains to be had on the RE mani with port-matching and honing... so I did it damnit. __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

11-12-2010, 12:19 PM	#6
sen2two KTEC Join Date: Jan 2009 Posts: 642 Rep Power: 0	There are plenty of designs online to build a home made flow bench on the cheap. I'm just wondering if its worth the space it will take up if your just doing it for fun. Now if I was competing or trying to break records, I would build one and test my manifolds before I did anything else... __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

11-12-2010, 12:12 AM	#3
JustJeff RCC Contributor Join Date: Mar 2008 Posts: 505 Rep Power: 18	^ Got any links. I understand the idea of port matching but not the procedure.

11-12-2010, 04:10 PM	#7
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son Posts: 4,581 Rep Power: 10	Links? I've got a spare set of mani's that are bone stock right now that I wouldn't mind testing before and after... __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

11-12-2010, 05:04 PM	#8
sen2two KTEC Join Date: Jan 2009 Posts: 642 Rep Power: 0	Did a quick google search and came up with this... I'm sure there's a ton of info here. A bunch of links came up when i searched diy flow bench. http://www.tractorsport.com/cgi-bin/.../ikonboard.cgi __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2 Last edited by sen2two; 11-12-2010 at 05:08 PM.

11-14-2010, 09:38 AM	#9
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	What is inportant is that the intake runners do not change in cross-sectional area throughout the entire length of the runner. This way the air can maintain a constant velocity. The runner should be slightly larger than the intake port, so that the air is accelerated through the port, resulting in better fuel mix. I polished my intake runners to 600 grit where dry and 160 grit where wet (after the injectors). If you polish the runner too much where they are wet, you will see a symptom called fuel pooling, which is the fuel forming rivulets on the polished surface. Fuel pooling will make the engine idle very poorly. 160 grit seems to have a small problem with fuel pooling, but nothing next to 600 grit. My engine will occasionally misfire at low fuel and air flow rates (idle, lightly loaded cruising), but the misfiring is infrequent and barely noticable. If I were you, I would probably not go past 80 grit past the injectors if you want a good idle. If you follow the rules of intake porting, there are major gains to be had from it. EDIT: Here is a thread where this was discussed. http://www.rotarycarclub.com/rotary_...ead.php?t=8550 __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic) Last edited by NoDOHC; 11-14-2010 at 09:41 AM.

11-14-2010, 11:21 AM	#10
JustJeff RCC Contributor Join Date: Mar 2008 Posts: 505 Rep Power: 18	Thanks for the link I'll read it later tonight What I have read so far about port matching is regarding piston engines. I'm sure it's the same idea but the lip created by variance between where two runners meet encourages the fuel to start coming out of suspension from the air. In other words the fuel starts sticking to walls of the runner at those points. What I don't understand yet is how you determine which lips/contact surfaces need matched. Or for that matter how much they are off from each other. With piston engines they talk about simply using a marker through cylinder heads and such. What I'm assuming I could do is use a light coat of paint or ink, simply bolt the parts together and then pull them apart. But that seems awfully prone to fucking it up. Seems like the amounts they will be off will me millimeters and any wiggle or smudging of the paint/ink will throw the whole measurement off. I'll be doing engine work today between football games and I'll look over the parts. Hopefully having parts in hand I can figure out answers to my questions.

11-14-2010, 11:47 AM	#11
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. Posts: 2,113 Rep Power: 20	Most people port match to the gaskets. Just sayin' __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

11-14-2010, 12:10 PM	#13
JustJeff RCC Contributor Join Date: Mar 2008 Posts: 505 Rep Power: 18	That sounds awfully prone to simply making them wider but not matched much better than the factory did. I'd think having them widen and then constrict back down would equally help pull the fuel out of suspension just as much as an uneven lip. Like NoDOHC posted. Hhmmm but perhaps allow the air to flow "better". I'll read what NoDOHC linked after lunch and some football.