Porting HP 440 exhaust manifolds?
#1316156
10/06/12 01:11 PM
10/06/12 01:11 PM
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Posts: 1,586 Tampa, FL
tpabayflyer
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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!!
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Re: Porting HP 440 exhaust manifolds?
[Re: tpabayflyer]
#1316157
10/06/12 01:21 PM
10/06/12 01:21 PM
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Joined: Nov 2011
Posts: 238 Florida, US
72ls5fla
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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.
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Re: Porting HP 440 exhaust manifolds?
[Re: 72ls5fla]
#1316158
10/06/12 01:34 PM
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tpabayflyer
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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!!
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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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mike s
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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
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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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kilroy
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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....
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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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Joined: Jan 2003
Posts: 1,586 Tampa, FL
tpabayflyer
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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!!
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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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tpabayflyer
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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!!
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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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Joined: May 2005
Posts: 416 Franklin Co. Illinois
runinonmt
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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
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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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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!!
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Re: Porting HP 440 exhaust manifolds?
[Re: BSB67]
#1316172
10/08/12 02:54 PM
10/08/12 02:54 PM
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tpabayflyer
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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!!
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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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dannysbee
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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.
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Re: Porting HP 440 exhaust manifolds?
[Re: dannysbee]
#1316174
10/08/12 03:31 PM
10/08/12 03:31 PM
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tpabayflyer
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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!!
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Re: Porting HP 440 exhaust manifolds?
[Re: Stewpar]
#1316176
10/09/12 12:06 AM
10/09/12 12:06 AM
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Posts: 295 Greensburg, Pa
Mpetros
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Quote:
Here's another option......
http://www.extrudehone.com/auto/auto-performance.php
I ran in a Class that You had to have Stock Manifolds.
I gasket matched a set and then sent the to get Power Flow.. The Extrudehone makes the like a glass finish the whole way thru.. You could never get in there to polish them like the Power Flow does..
If You call them ask for Joe in Power Flow.. He knows whats going on.
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Re: Porting HP 440 exhaust manifolds?
[Re: BSB67]
#1316178
10/09/12 07:05 PM
10/09/12 07:05 PM
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Joined: Feb 2005
Posts: 4,310 Prospect, PA
BSB67
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Quote:
What is the ID of your exhaust tubing?
Have you measured the inside diameter of the exhaust pipe yet? I think it is 2 3/8". Mine are.
If it is, you really dont want to step down from 2 1/2 to 2 3/8 in the direction of flow.
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Re: Porting HP 440 exhaust manifolds?
[Re: BSB67]
#1316179
10/09/12 10:43 PM
10/09/12 10:43 PM
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Joined: Jan 2003
Posts: 1,586 Tampa, FL
tpabayflyer
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Good question... I did not consider that but I think you are right! Thinking about using the TTI down pipes in the 3" size and then 2 1/2 after the x-pipe to the tailpipes... If I have to grind out the head pipes to 2 1/2 than I guess I will have too..... I will get with TTI tomorrow and ask them the inside diameter of there headpipes.... I already opened up the exhaust flanges to the 2 1/2" size so I may have to fire up the ole makita die grinder and let it rip on the headpipes when I get them! TBF
71 Challenger 528 Hemi project 09 Gr Cherokee 5.7 hemi in da house!!
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Re: Porting HP 440 exhaust manifolds?
[Re: tpabayflyer]
#1316181
10/25/12 12:09 PM
10/25/12 12:09 PM
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tpabayflyer
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After a bit of research it looks like the max gain to expect from porting the HP exhaust is a few peak horsepower gain...... However, there was a gain of 10ft/lbs of torque in the mid rpm range so every little bit helps! TBF
71 Challenger 528 Hemi project 09 Gr Cherokee 5.7 hemi in da house!!
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Re: Porting HP 440 exhaust manifolds?
[Re: lenny459]
#1316183
11/19/12 11:17 AM
11/19/12 11:17 AM
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Joined: Oct 2012
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VincentVega
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Here is my opinion. You are doing yourself a disservice HP-wise by sticking with manifolds. I understand the argument for manifolds on the street. They're cheap, reliable, and you already own them. That, and headers are known for being a PITA. Then there's the installation, the scraping, the leaking... blah What is the argument FOR headers? properly sized, better HP and toque all across the range. In your scope, for something around 500HP, you're almost assuredly giving up 40-60hp (this is dyno proven) by not using a good header and appropriately sized exhaust. So the question becomes: do you care? if not, stick with what you got, and you'll never have to worry about exhaust until rust eats a hole in it somewhere. If you want the reliability, don't hog out the outlets for reasons stated. You won't feel the gain, but the cast iron will feel the loss. By all means gasket match if you feel there is enough meat there, and take off the sharp edges. beyond that, I'd live with them as-is. or find some of those nice max-wedge cast iron headers
Looking for 1975 through 1978 B body 4 door sedan sheet metal or parts cars - monaco, fury, coronet. Please let me know
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Re: Porting HP 440 exhaust manifolds?
[Re: VincentVega]
#1316184
11/19/12 08:12 PM
11/19/12 08:12 PM
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72blubird
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You will lose power. I did comparison on a dyno in August. 502hp with headers at 5800 rpm and climbing to 468 hp at 5400 rpm. About a 7% loss is that enough to deal with headers that you can only decide. This motor is stroker 400 w/ aluminum heads and intake exhaust not matched.
What was I thinking....
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