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Porting HP 440 exhaust manifolds? #1316156
10/06/12 01:11 PM
10/06/12 01:11 PM
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Tampa, FL
tpabayflyer Offline OP
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tpabayflyer  Offline OP
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My 451 sixpack with mild hyd roller cam and edelbrock heads should make around 500hp so I decided to stay with a stock look and go with exhaust manifolds. The flanges are around 2 3/8 diameter and I will be going with 2 1/2" exhaust all the way back so I was thinking about getting the grinder out and opening up the flanges to the 2 1/2"size. Looks like there is enough material there to not worry about cracking. The exhaust flanges are not that even and I will smooth them out as well and generally just clean things up a bit....... Anybody else do something like this? TBF


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316157
10/06/12 01:21 PM
10/06/12 01:21 PM
Joined: Nov 2011
Posts: 238
Florida, US
72ls5fla Offline
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this is just one persons opionion...

I would not port the manifolds. The casting is somewhat thick, but the consistency throught out the manifold is horrible - thinner in spots than others.
Plus they are horrible for cracking under stress, specially the PASS side.

I also wonder if all th effort to port them would really yeild all that much performance, as opposed to a great set of headers?

My 2 cents ....

Bill


Got me a NEW Project
1970 GTX 440+6, 4 spd, 4.10 Dana and N96 FE5 (top/bottom) and black bucket interior.
Original transmission and Dana - Engine is a service replacement block.

Body has all stamped #s + VIN/TRIM tag and door sticker. Been hunting like all hell to find the Build Sheet.

garage find, only had 41,850 miles on ODO.
Re: Porting HP 440 exhaust manifolds? [Re: 72ls5fla] #1316158
10/06/12 01:34 PM
10/06/12 01:34 PM
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Tampa, FL
tpabayflyer Offline OP
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I agree, I don't think much power will be gained at all but I figured since I have them off why not do a little cleanup? I read Andy F,s article about making good power with exhaust manifolds and the key is keeping the cam on the mild side. I am going to pass on the headers as I am looking for a stock appearance and 500HP should be plenty!


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316159
10/06/12 01:41 PM
10/06/12 01:41 PM
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Wisconsin
Stewpar Offline
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Admiration For Multiple Carburetor Vehicles...
Re: Porting HP 440 exhaust manifolds? [Re: Stewpar] #1316160
10/06/12 01:55 PM
10/06/12 01:55 PM
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Mi,U.S.A.
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mike s Offline
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Just clean up any flash,match the exh ports and use them.They will work fine.Porting gains are very small even w/the extrude hone process. <10h.p.


Leave the gun.......take the Cannoli's....Mike
Re: Porting HP 440 exhaust manifolds? [Re: mike s] #1316161
10/06/12 02:05 PM
10/06/12 02:05 PM
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Kelowna, B.C. Canada
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DPelletier Offline
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Quote:

Just clean up any flash,match the exh ports and use them.They will work fine.Porting gains are very small even w/the extrude hone process. <10h.p.






Dave


1970 Super Bee 440 Six Pack 1974 'Cuda 2008 Ram 3500 Diesel 2006 Ram 3500 Diesel 2004.5 Ram 2500 Diesel 2003 Ram 3500 Diesel 2006 Durango Limited [url] http://1970superbee.piczo.com [/url]
Re: Porting HP 440 exhaust manifolds? [Re: DPelletier] #1316162
10/06/12 02:32 PM
10/06/12 02:32 PM
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Iowa State fan
kilroy Offline
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Ive thought about this and heard the same. What about just port matching to smooth out flow?


1973 Charger, former SE, former auto

I'm not trying to be difficult, it comes naturally....
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316163
10/06/12 02:59 PM
10/06/12 02:59 PM
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Prospect, PA
BSB67 Offline
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Did you get a custom ground cam specifically for the manifolds. If not, that could be where you will see some better and more worthwhile gains verses the porting

Re: Porting HP 440 exhaust manifolds? [Re: kilroy] #1316164
10/06/12 03:06 PM
10/06/12 03:06 PM
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Posts: 1,586
Tampa, FL
tpabayflyer Offline OP
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I already drilled and tapped 2 plugs into the heat riser valve holes so that should help a little...... I think I will open the exit flange up to the 2 1/2 size and do little port match on the exhaustside and call it good! TBF


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316165
10/06/12 03:18 PM
10/06/12 03:18 PM
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Posts: 1,586
Tampa, FL
tpabayflyer Offline OP
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Cam is crane HR #689521 and a lift of .509int/.528ex with duration at .050 of 222/230..... Nice bump over a stock cam but still mild enough for power brakes..... Andy used the .528 mopar solid and it was the best cam of any he tested for use with the HP exhaust manifolds.....

I should also mention that I will be using 1.6 rockers so that puts my lift up around .540/.560. the Mopar solid has a lot of lash at .028/.032 but Andy also used 1.6 rockers so I should be around the same effective lift and my cam shows a little less duration at .050 vs, the .241 of the solid cam but the same adv duration of .284 on the intake and a little more on the exhaust at .290 vs. .284 The power range of the cam is 1,800 - 6,000 so I am sure I am giving up some power as opposed to headers but I am trying to max out this combo for use with manifolds and I think I have done my homework and have about the best combo for a dual plane sixpack intake using manifolds.... I want to look and sound stock and make people wonder how they got beat by a "stock" 440 sixpack!


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316166
10/07/12 02:21 AM
10/07/12 02:21 AM
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southern California
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1970sixpak Offline
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I ported mine and my it runs good, not sure if it actually helped though.

Re: Porting HP 440 exhaust manifolds? [Re: 1970sixpak] #1316167
10/07/12 11:46 AM
10/07/12 11:46 AM
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Franklin Co. Illinois
runinonmt Offline
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Franklin Co. Illinois
Depending on how much the ports mismatch,there is power to be gained with a port match. It made a HUGE difference on a '75 Toyota I had. They were off by 1/16". Never dynoed it but it never lost speed on a hill in 5th gear again. Best part - it only costs time unless you don't already have a die grinder. If you plan to use a 2 1/2" exhaust open up the manifolds if there's room.
Ron


In sixty-five I was seventeen and running up one-o-one I don't know where I'm running now, I'm just running on Jackson Browne-Running On Empty
Re: Porting HP 440 exhaust manifolds? [Re: runinonmt] #1316168
10/07/12 11:49 AM
10/07/12 11:49 AM
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Phila Pa
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scatpacktom Offline
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On a 600hp engine it might be worth 3 hp so if I were you I would look elsewhere

Re: Porting HP 440 exhaust manifolds? [Re: scatpacktom] #1316169
10/07/12 12:42 PM
10/07/12 12:42 PM
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Chilliwack B.C. Canada
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RUNCHARGER Offline
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I'd prefer to have the castings as thick as possible rather than ported for very minute gain. I would clean up any casting flash though.

Sheldon

Re: Porting HP 440 exhaust manifolds? [Re: RUNCHARGER] #1316170
10/07/12 04:23 PM
10/07/12 04:23 PM
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Tampa, FL
tpabayflyer Offline OP
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I will post a few before and after pics when I get finished!! I think I need to do some cleanup work and port matching on the exhaust ports on the edelbrock heads.....


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316171
10/07/12 07:53 PM
10/07/12 07:53 PM
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Prospect, PA
BSB67 Offline
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What is the ID of your exhaust tubing?

Re: Porting HP 440 exhaust manifolds? [Re: BSB67] #1316172
10/08/12 02:54 PM
10/08/12 02:54 PM
Joined: Jan 2003
Posts: 1,586
Tampa, FL
tpabayflyer Offline OP
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I actually found a correct date coded set for my 71 Challenger R/T Clone project...... 2951865 RT and 2989879 LT side... My goals for my project are to pretty much build a brand new 71 challenger with common sense upgrades so the car actually handles, stops, and goes much better than any stock car could. WIth a 3.54 gear Dana 60 and 500HP on tap it should be able to knock down easy 12's in the quarter while looking the part of a high dollar show car.... I am thinking about adding AC as well but need to figure out the compressor mounting with a shaker setup....


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316173
10/08/12 03:08 PM
10/08/12 03:08 PM
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Texas
dannysbee Offline
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Sounds like a cool project. How about keeping the manifolds close to stock and porting the flanges to gasket size. That way there would be a step to help with reversion. I had a set we opened up to full 2.5 on a mill. It did not show up on the time slip on a 451 inch engine.


Getting old just means you were smarter than some and luckier than others.
Re: Porting HP 440 exhaust manifolds? [Re: dannysbee] #1316174
10/08/12 03:31 PM
10/08/12 03:31 PM
Joined: Jan 2003
Posts: 1,586
Tampa, FL
tpabayflyer Offline OP
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Thanks Dan! I already opened up the flanges! easy work and still plenty of meat for a good seal and strength. I went in a few inches to make a nice gradual transition to the flange so hopefully that smooths out the flow a bit....I will look into the reversion theory... I think that is more of a factor with cams that have higher overlap? I might email Andy and get his take on that! If it sounds like I have too much time on my hands I do! Lost my job as a Pilot so using this free time to finish my project.... TBF


71 Challenger 528 Hemi project
09 Gr Cherokee 5.7 hemi in da house!!
Re: Porting HP 440 exhaust manifolds? [Re: tpabayflyer] #1316175
10/08/12 10:56 PM
10/08/12 10:56 PM
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Posts: 74,907
U.S.S.A.
JohnRR Offline
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U.S.S.A.
I did a set of stock manifolds , the heads used had the exhuast port opened to the size of the gasket that comes in the felpro set , actually they were a little bigger , I opened up the gasket and then set it on the manifold the 2 end ports were the worst , over an 3/16" narrower and at least a 1/16" top to bottom ... Time well spent

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