Home » Public Forums » GMCnet » Weekend DIY Header
| Weekend DIY Header [message #162235] |
Sun, 04 March 2012 20:57  |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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This is different than Doug Thorley.
I posted some photos of my DIY exhaust header. It's more work than I realized. It looks like it came off a boat. And it has that custom appearance. What would I do on weekends without having the GMC to work on?
http://www.gmcmhphotos.com/photos/showgallery.php?cat=6029
Regards,
Bill
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: Weekend DIY Header [message #162239 is a reply to message #162235] |
Sun, 04 March 2012 21:02  |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Thanks! It was a lot of work and a learning experience.
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] Weekend DIY Header [message #162247 is a reply to message #162235] |
Sun, 04 March 2012 21:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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I don't know anything about tuning headers, so it looks great to me.
What I want to know, though, is why didn't you convert to a Cad500
before you started manufacturing them? I'd be on the waiting list.
:-)
Ken H.
On Sun, Mar 4, 2012 at 9:57 PM, Bill Wevers wrote:
>
>
> This is different than Doug Thorley.
>
> I posted some photos of my DIY exhaust header. It's more work than I realized. It looks like it came off a boat. And it has that custom appearance. What would I do on weekends without having the GMC to work on?
>
>
> http://www.gmcmhphotos.com/photos/showgallery.php?cat=6029
>
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Weekend DIY Header [message #162249 is a reply to message #162248] |
Sun, 04 March 2012 22:01 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Naaah, you've done your duty -- for THIS week. :-)
Finally got all the pre-loads to suit me today except for #2, the one
on which I ground the pedestal. That one's high on one side and low
on the other (even when it's turned around). But from what I've seen
of all-over-the-yard specs, on something that's supposed to be
self-adjusting, I don't think 0.067" and 0.027" are worth losing any
more sleep about.
Ken H.
On Sun, Mar 4, 2012 at 10:45 PM, Kosier <gkosier@roadrunner.com> wrote:
> Do I feel something poking me in the behind?
>
> Gary Kosier
>
> ----- Original Message -----
> From: "Ken Henderson" <hend4800@bellsouth.net>
> To: <gmclist@temp.gmcnet.org>
> Sent: Sunday, March 04, 2012 10:33 PM
> Subject: Re: [GMCnet] Weekend DIY Header
>
>
>>I don't know anything about tuning headers, so it looks great to
>>me.
>>
>> What I want to know, though, is why didn't you convert to a
>> Cad500
>> before you started manufacturing them? Â I'd be on the waiting
>> list.
>> :-)
>>
>> Ken H.
>>
>>
>> On Sun, Mar 4, 2012 at 9:57 PM, Bill Wevers wrote:
>>>
>>>
>>> This is different than Doug Thorley.
>>>
>>> I posted some photos of my DIY exhaust header. It's more work
>>> than I realized. It looks like it came off a boat. And it has
>>> that custom appearance. What would I do on weekends without
>>> having the GMC to work on?
>>>
>>>
>>> http://www.gmcmhphotos.com/photos/showgallery.php?cat=6029
>>>
>> _______________________________________________
>> GMCnet mailing list
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Weekend DIY Header [message #162251 is a reply to message #162235] |
Sun, 04 March 2012 22:13 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Bill,
The headers are very nicely done -- thanks for sharing the photos.
Do you have plans for the balance of the exhaust system? Or perhaps those changes are already complete?
Dennis
| bwevers wrote on Sun, 04 March 2012 20:57 |
This is different than Doug Thorley.
I posted some photos of my DIY exhaust header. It's more work than I realized. It looks like it came off a boat. And it has that custom appearance. What would I do on weekends without having the GMC to work on?
http://www.gmcmhphotos.com/photos/showgallery.php?cat=6029
Regards,
Bill
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Weekend DIY Header [message #162260 is a reply to message #162235] |
Sun, 04 March 2012 23:37 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Senior Member |
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Dennis,
I replaced the mufflers a few years ago with
large "turbo" mufflers, 2.5inch pipes running
into a 3 inch tailpipe. For now I'm going to
stay with them.
Regards,
Bill
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: Weekend DIY Header [message #162295 is a reply to message #162235] |
Mon, 05 March 2012 17:50 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Looks fantastic. I'll be interested in the performance though as fat and short tubes usually cause a loss of low end torque. At a glance it looks like a high RPM design. In the real world it will be very low restriction( That's for sure!) and with all the road load we have to overcome, losses may be immeasurable in the big picture. You have a talent.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Weekend DIY Header [message #162303 is a reply to message #162299] |
Mon, 05 March 2012 19:33 |
jknezek
Messages: 1057
Registered: December 2007
Karma: 5
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| ahamilto wrote on Mon, 05 March 2012 19:40 |
It looked to me like a stock manifold made out of tubing and a flange. I thought the flow would be close to the OEM design.
|
Look closer. A manifold accumulates all the exhaust gas in the manifold from 4 cylinders before using the strokes from all cylinders to try and push the accumulation of gas into the exhaust system. In headers, each cylinder is responsible for pushing only its own exhaust gas into the exhaust system (collector). Each pipe is supposed to be exactly the same length so each cylinder has to work the same amount to clear the gasses.
Headers should eliminate back pressure and inefficiencies in the exhaust stroke that are caused by a manifold aggregating exhaust gasses just above the cylinders. In my case, I found the Thorley headers to be a huge improvement over the manifold. Of course, any manifold that is cracked would experience an improvement just by solving that issue, and mine was potentially cracked.
The flip side is that creating headers is an art form. Different sizes and shapes, different lengths, and different bends can all have different effects at various rpms. I love my headers and was thrilled that someone had gone through the art of making a viable alternative without me having to think about it.
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
[Updated on: Mon, 05 March 2012 19:35] Report message to a moderator |
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| Re: [GMCnet] Weekend DIY Header [message #162306 is a reply to message #162303] |
Mon, 05 March 2012 19:58 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Somehow that sounds a little convoluted. Maybeso one of the techy gurus can gimme a better understanding of how a manifold works. And someplace the idea of scavenging was enhanced by pipe length....Although admittedly I always just asked the guys at Mopar Performance or Hooker and took them at thier word.
Back in the late 60s, one of Mr Kanomata's countrymen 'splained to a couple of us at Talladega how ringding exhausts work. The idea being to have a shock wave appear at the exhaust port of the engine just as the incoming charge gets to that port, which causes it to curl upwards and lets a lot more gas/air in the cylinder. Exactly how that happened was about as much black magic as anything else, but they had a set on a Suzuki water buffalo that Jody Nicholas took out and blew everyone away with.
I got the impression that one can get substantially more good out of two stroke exhaust systems than one can out of four strokes, percentage wise.
--johnny
'76 23' transmode norris
'76 palm beach
________________________________
From: Jeremy <jtknezek@hotmail.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, March 5, 2012 8:33 PM
Subject: Re: [GMCnet] Weekend DIY Header
ahamilto wrote on Mon, 05 March 2012 19:40
> It looked to me like a stock manifold made out of tubing and a flange. I thought the flow would be close to the OEM design.
Look closer. A manifold accumulates all the exhaust gas in the manifold from 4 cylinders before using one stroke from all cylinders to try and push the accumulation of gas into the exhaust system. In headers, each cylinder is responsible for pushing only its own exhaust gas into the exhaust system (collector). Each pipe is supposed to be exactly the same length so each cylinder has to work the same amount to clear the gasses.
Headers should eliminate back pressure and inefficiencies in the exhaust stroke that are caused by a manifold aggregating exhaust gasses just above the cylinders. In my case, I found the Thorley headers to be a huge improvement over the manifold. Of course, any manifold that is cracked would experience an improvement just by solving that issue, and mine was potentially cracked.
The flip side is that creating headers is an art form. Different sizes and shapes, different lengths, and different bends can all have different effects at various rpms. I love my headers and was thrilled that someone had gone through the art of making a viable alternative without me having to think about it.
--
Thanks,
Jeremy Knezek
1976 Glenbrook
Birmingham, AL
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Weekend DIY Header [message #162320 is a reply to message #162306] |
Mon, 05 March 2012 22:55 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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There isn't a lot of black magic with gas flowing through a pipe. On two
strokes, you are more concerned with the shock wave of the combustion event
traveling through the spent exhaust gas mixture in the expansion cone, then
being reflected back towards the exhaust port at the same time the fuel air
is trying to exit. It creates a pressure ridge that stops the fuel air from
exiting out the pipe, and kinda has a mild supercharging effect. Tuners
call that sweet spot "being on the pipe" Four cycle engines have a lot more
time (twice as much) to charge the cylinder, and with valves closing off
the passages, they are not as affected. In general terms, High volume,
large diameter header pipes work well in the higher RPM ranges at the
expense of low RPM performance. Thorley headers that are made for our
Oldsmobile engines work substantially better at lower RPMs than they do at
higher RPMs. All are affected by throttle opening, camshaft design,
compression ratios, etc.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Mar 5, 2012 at 5:58 PM, Johnny Bridges <jhbridges@ymail.com> wrote:
> Somehow that sounds a little convoluted. Maybeso one of the techy gurus
> can gimme a better understanding of how a manifold works. And someplace
> the idea of scavenging was enhanced by pipe length....Although admittedly I
> always just asked the guys at Mopar Performance or Hooker and took them at
> thier word.
> Back in the late 60s, one of Mr Kanomata's countrymen 'splained to a
> couple of us at Talladega how ringding exhausts work. The idea being to
> have a shock wave appear at the exhaust port of the engine just as the
> incoming charge gets to that port, which causes it to curl upwards and lets
> a lot more gas/air in the cylinder. Exactly how that happened was about as
> much black magic as anything else, but they had a set on a Suzuki water
> buffalo that Jody Nicholas took out and blew everyone away with.
> I got the impression that one can get substantially more good out of two
> stroke exhaust systems than one can out of four strokes, percentage wise.
>
> --johnny
> '76 23' transmode norris
> '76 palm beach
>
>
> ________________________________
> From: Jeremy <jtknezek@hotmail.com>
> To: gmclist@temp.gmcnet.org
> Sent: Monday, March 5, 2012 8:33 PM
> Subject: Re: [GMCnet] Weekend DIY Header
>
>
>
> ahamilto wrote on Mon, 05 March 2012 19:40
> > It looked to me like a stock manifold made out of tubing and a flange.
> I thought the flow would be close to the OEM design.
>
>
> Look closer. A manifold accumulates all the exhaust gas in the manifold
> from 4 cylinders before using one stroke from all cylinders to try and push
> the accumulation of gas into the exhaust system. In headers, each cylinder
> is responsible for pushing only its own exhaust gas into the exhaust system
> (collector). Each pipe is supposed to be exactly the same length so each
> cylinder has to work the same amount to clear the gasses.
>
> Headers should eliminate back pressure and inefficiencies in the exhaust
> stroke that are caused by a manifold aggregating exhaust gasses just above
> the cylinders. In my case, I found the Thorley headers to be a huge
> improvement over the manifold. Of course, any manifold that is cracked
> would experience an improvement just by solving that issue, and mine was
> potentially cracked.
>
> The flip side is that creating headers is an art form. Different sizes and
> shapes, different lengths, and different bends can all have different
> effects at various rpms. I love my headers and was thrilled that someone
> had gone through the art of making a viable alternative without me having
> to think about it.
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
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> Unsubscribe or Change List Options:
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| Re: [GMCnet] Weekend DIY Header [message #162323 is a reply to message #162320] |
Tue, 06 March 2012 00:56 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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The Thorley are matched for the 403 ports, our Dougs headers by
Pertronics are matched for the 455. We carry both in stock.
You'll not notice a differance till you look at the ports.
Dick Patterson can tell you there is a differance in the opening, and
feels it's worth it.
On Mon, Mar 5, 2012 at 8:55 PM, James Hupy <jamesh1296@gmail.com> wrote:
> There isn't a lot of black magic with gas flowing through a pipe. On two
> strokes, you are more concerned with the shock wave of the combustion event
> traveling through the spent exhaust gas mixture in the expansion cone, then
> being reflected back towards the exhaust port at the same time the fuel air
> is trying to exit. It creates a pressure ridge that stops the fuel air from
> exiting out the pipe, and kinda has a mild supercharging effect. Tuners
> call that sweet spot "being on the pipe" Four cycle engines have a lot more
> time (twice as much) to charge the cylinder, and with valves closing off
> the passages, they are not as affected. In general terms, High volume,
> large diameter header pipes work well in the higher RPM ranges at the
> expense of low RPM performance. Thorley headers that are made for our
> Oldsmobile engines work substantially better at lower RPMs than they do at
> higher RPMs. All are affected by throttle opening, camshaft design,
> compression ratios, etc.
> Jim Hupy
> Salem, OR
> 78 GMC Royale 403
>
> On Mon, Mar 5, 2012 at 5:58 PM, Johnny Bridges <jhbridges@ymail.com> wrote:
>
>> Somehow that sounds a little convoluted. Â Maybeso one of the techy gurus
>> can gimme a better understanding of how a manifold works. Â And someplace
>> the idea of scavenging was enhanced by pipe length....Although admittedly I
>> always just asked the guys at Mopar Performance or Hooker and took them at
>> thier word.
>> Back in the late 60s, one of Mr Kanomata's countrymen 'splained to a
>> couple of us at Talladega how ringding exhausts work. Â The idea being to
>> have a shock wave appear at the exhaust port of the engine just as the
>> incoming charge gets to that port, which causes it to curl upwards and lets
>> a lot more gas/air in the cylinder. Â Exactly how that happened was about as
>> much black magic as anything else, but they had a set on a Suzuki water
>> buffalo that Jody Nicholas took out and blew everyone away with.
>> I got the impression that one can get substantially more good out of two
>> stroke exhaust systems than one can out of four strokes, percentage wise.
>>
>> --johnny
>> '76 23' transmode norris
>> '76 palm beach
>>
>>
>> ________________________________
>> From: Jeremy <jtknezek@hotmail.com>
>> To: gmclist@temp.gmcnet.org
>> Sent: Monday, March 5, 2012 8:33 PM
>> Subject: Re: [GMCnet] Weekend DIY Header
>>
>>
>>
>> Â ahamilto wrote on Mon, 05 March 2012 19:40
>> > It looked to me like a stock manifold made out of tubing and a flange.
>> I thought the flow would be close to the OEM design.
>>
>>
>> Look closer. A manifold accumulates all the exhaust gas in the manifold
>> from 4 cylinders before using one stroke from all cylinders to try and push
>> the accumulation of gas into the exhaust system. In headers, each cylinder
>> is responsible for pushing only its own exhaust gas into the exhaust system
>> (collector). Each pipe is supposed to be exactly the same length so each
>> cylinder has to work the same amount to clear the gasses.
>>
>> Headers should eliminate back pressure and inefficiencies in the exhaust
>> stroke that are caused by a manifold aggregating exhaust gasses just above
>> the cylinders. In my case, I found the Thorley headers to be a huge
>> improvement over the manifold. Of course, any manifold that is cracked
>> would experience an improvement just by solving that issue, and mine was
>> potentially cracked.
>>
>> The flip side is that creating headers is an art form. Different sizes and
>> shapes, different lengths, and different bends can all have different
>> effects at various rpms. I love my headers and was thrilled that someone
>> had gone through the art of making a viable alternative without me having
>> to think about it.
>> --
>> Thanks,
>> Jeremy Knezek
>> 1976 Glenbrook
>> Birmingham, AL
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Weekend DIY Header [message #162326 is a reply to message #162295] |
Tue, 06 March 2012 02:17 |
 |
mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| JohnL455 wrote on Mon, 05 March 2012 15:50 |
Looks fantastic. I'll be interested in the performance though as fat and short tubes usually cause a loss of low end torque. At a glance it looks like a high RPM design. In the real world it will be very low restriction( That's for sure!) and with all the road load we have to overcome, losses may be immeasurable in the big picture. You have a talent.
|
I agree Bill has talent.
I do not know much about header/manifold design but I do remember the Arch's dyno runs. The runs with manifolds had higher torque -- mostly at the low end. It looks to me that Bill's headers are more like "non-cast" manifolds, and would have flow/torque/HP curves to match. Could be a good thing. It would take a few dyno runs to prove anything... then people would still argue about it.
It would be easier to put heat shields on Bill's design than any header.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Weekend DIY Header [message #162327 is a reply to message #162320] |
Tue, 06 March 2012 06:34 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
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|
My 23' road coach has a set of Thorleys. Beyond that it is as far as I can tell box stock. It has a very nice off - idle throttle response though. Can't really compare it to my PB, the latter has an exhaust leak which is either a hosed gasket or cracked manifold, and when I drove it home the brakes were pretty much non-existant so I never got into it. It (the PB) is why I'm interested in the headers he pictured.
We put a set of Hookers on a 413 'long ram' setup in a '62 Polara and got a really nice ride out of it... excepting the brakes on those things were marginal to begin with. And it was a firebug due to the intake geometry. Used to push the button around 5100 on it, which was just over the peak, and would put the old ride sideways in the street. Nobody had much of a 4-speed that would live behind the big blocks, but the TorqueFlite was an anvil so we set them up for an automatic.
From: James Hupy <jamesh1296@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, March 5, 2012 11:55 PM
Subject: Re: [GMCnet] Weekend DIY Header
There isn't a lot of black magic with gas flowing through a pipe. On two
strokes, you are more concerned with the shock wave of the combustion event
traveling through the spent exhaust gas mixture in the expansion cone, then
being reflected back towards the exhaust port at the same time the fuel air
is trying to exit. It creates a pressure ridge that stops the fuel air from
exiting out the pipe, and kinda has a mild supercharging effect. Tuners
call that sweet spot "being on the pipe" Four cycle engines have a lot more
time (twice as much) to charge the cylinder, and with valves closing off
the passages, they are not as affected. In general terms, High volume,
large diameter header pipes work well in the higher RPM ranges at the
expense of low RPM performance. Thorley headers that are made for our
Oldsmobile engines work substantially better at lower RPMs than they do at
higher RPMs. All are affected by throttle opening, camshaft design,
compression ratios, etc.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Mar 5, 2012 at 5:58 PM, Johnny Bridges <jhbridges@ymail.com> wrote:
> Somehow that sounds a little convoluted. Maybeso one of the techy gurus
> can gimme a better understanding of how a manifold works. And someplace
> the idea of scavenging was enhanced by pipe length....Although admittedly I
> always just asked the guys at Mopar Performance or Hooker and took them at
> thier word.
> Back in the late 60s, one of Mr Kanomata's countrymen 'splained to a
> couple of us at Talladega how ringding exhausts work. The idea being to
> have a shock wave appear at the exhaust port of the engine just as the
> incoming charge gets to that port, which causes it to curl upwards and lets
> a lot more gas/air in the cylinder. Exactly how that happened was about as
> much black magic as anything else, but they had a set on a Suzuki water
> buffalo that Jody Nicholas took out and blew everyone away with.
> I got the impression that one can get substantially more good out of two
> stroke exhaust systems than one can out of four strokes, percentage wise.
>
> --johnny
> '76 23' transmode norris
> '76 palm beach
>
>
> ________________________________
> From: Jeremy <jtknezek@hotmail.com>
> To: gmclist@temp.gmcnet.org
> Sent: Monday, March 5, 2012 8:33 PM
> Subject: Re: [GMCnet] Weekend DIY Header
>
>
>
> ahamilto wrote on Mon, 05 March 2012 19:40
> > It looked to me like a stock manifold made out of tubing and a flange.
> I thought the flow would be close to the OEM design.
>
>
> Look closer. A manifold accumulates all the exhaust gas in the manifold
> from 4 cylinders before using one stroke from all cylinders to try and push
> the accumulation of gas into the exhaust system. In headers, each cylinder
> is responsible for pushing only its own exhaust gas into the exhaust system
> (collector). Each pipe is supposed to be exactly the same length so each
> cylinder has to work the same amount to clear the gasses.
>
> Headers should eliminate back pressure and inefficiencies in the exhaust
> stroke that are caused by a manifold aggregating exhaust gasses just above
> the cylinders. In my case, I found the Thorley headers to be a huge
> improvement over the manifold. Of course, any manifold that is cracked
> would experience an improvement just by solving that issue, and mine was
> potentially cracked.
>
> The flip side is that creating headers is an art form. Different sizes and
> shapes, different lengths, and different bends can all have different
> effects at various rpms. I love my headers and was thrilled that someone
> had gone through the art of making a viable alternative without me having
> to think about it.
> --
> Thanks,
> Jeremy Knezek
> 1976 Glenbrook
> Birmingham, AL
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Weekend DIY Header [message #162341 is a reply to message #162332] |
Tue, 06 March 2012 11:20 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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Looking at those data, I would hazard the guess
that any gain is likely to be minimal and only
observed by test equipment and NOT seat of the
pants feel.
Therefore, only advisable if original manifolds
fail and direct replacements are not available.
Just what I'd do or not do. YRMV.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~~ k2gkk @ hotmail dot com ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
_______________
*[ ]....[][ ][]\
*--OO---[]---O-*
> From: robmueller@iinet.net.au
> To: gmclist@temp.gmcnet.org
> Date: Tue, 6 Mar 2012 09:39:31 -0600
> Subject: Re: [GMCnet] Weekend DIY Header
>
> G'day,
>
> Here's a link to a spreadsheet I put together from info on Jim B's website:
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=40002
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Mike Miller
>
>
> I agree Bill has talent.
>
> I do not know much about header/manifold design but I do remember the Arch's
> dyno runs. The runs with manifolds had higher torque -- mostly at the low
> end. It looks to me that Bill's headers are more like "non-cast" manifolds,
> and would have flow/torque/HP curves to match. Could be a good thing. It
> would take a few dyno runs to prove anything... then people would still
> argue about it.
>
> It would be easier to put heat shields on Bill's design than any header.
>
> --
> Mike
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| Re: [GMCnet] Weekend DIY Header [message #162359 is a reply to message #162341] |
Tue, 06 March 2012 21:10 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Mac,
At least it's REAL data! Seat of the pants feeling is seriously affected by
the amount of money that is spent to make the mod.
OR the more one spends on a mod the better the results! ;-)
How many times have you heard someone say; "boy, I pissed away big bucks on
that super duper whatnot!"
Regards,
Rob M.
-----Original Message-----
From: D C *Mac* Macdonald
Looking at those data, I would hazard the guess
that any gain is likely to be minimal and only
observed by test equipment and NOT seat of the
pants feel.
Therefore, only advisable if original manifolds
fail and direct replacements are not available.
Just what I'd do or not do. YRMV.
~~ ~ D C "Mac" Macdonald ~ ~~
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GMCnet mailing list
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http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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