[Jim Hand]

The note below is copied from the "X Pipe" thread:

Jim & Tom,
Could you please summarize the complete, present Exhaust system on the wagon that works? [I haven't subscribed to a glitter mag since 91, so this thread is it] Include status of head cross-over blockage. manifold/header type, headpipe details, X position, muffler model, length, tailpipe dia.
Thank you,
Half-Inch Stud

To Half-Inch Stud (can I just refer to you as .5"?) and to all members:

Several caveats are in order: Sound is very subjective and what sounds great to one may not be aceptable to the next person. As a good dual system makes any muffler work better, an excellent dual system causes most modern "HIPO" mufflers to perform similarly. Finally, Pontiac Dude has indicated his attention span is fairly short, so will try to keep this relatively brief. May make additional postings on some of the details.

The exhaust system that we have run on the wagon for the past several years consists of:

Home ported #64 heads that produce 10.07 CR, have peak exhaust flow of 202@28 as measured with two inch straight extension stubs on the ports, and have the crossovers filled with aluminum.

Headers are Hooker 1 ¾" primaries, 3" secondaries (Super Comp), with two inch additional length added to the left header primary tubes to equalize the average primary length between the two headers. Extensive welding and recutting to obtain optimum alignment of the openings to the head ports. Reduced the mounting hole size on front and back to assure correct alignment when installing. Have had the headers coated by Airborn Coatings - no noticeable performance difference but they look better.

Dr. Gas 3" X system from the headers to the rear just in front of the mufflers. It is located as far forward as allowed by the driveshaft safety loop. MFG states to install as far forward as possible, but the transmission, loop, and possibly other factors will dictate actual location. The 3" pipes out of the X are routed into Flowmaster 3" into 2 ½" cone reducers.

I have two sets of mufflers that we use: Dynomax 17749, which is a reverse flow unit with deflectors built in to turn the exhaust, and are packed with fiberglass. These mufflers have a body size of 4 ½" X 9 ½" and 20" length, and are 2 ½" OD side inlet, side outlet. The overall length as received is 25 ¼". This muffler is the quietest of all the performance mufflers we have tried and is used when we desire the quietest possible sound. These mufflers are available for about $40 each.

The other set we use is the Dynomax 17289, which is the Ultra Flow series. This is an identical physical package as the 17749. It is a straight through muffler with a mandrel bent pass tube of full 2 ½" diameter. The pass tube has carefully cut and sized holes to minimize any flow restrictions but to allow some sound to pass into the muffler body. The pass tube is wrapped with a layer of steel wool matting. The case is filled with special spun glass strands. The internal case has tuning chambers on both interior ends to absorb certain frequencies. The performance of these two mufflers is very close, with the ET being identical, but the MPH is improved very slightly (tenths of a MPH) with the Ultra Flow straight through muffler. The downside is that it is allows a bit more sound to pass through so they are a little louder out the pipes, but are still acceptable under all driving conditions. The Ultra Flow is a premium muffler made completely of stainless (except for the glass packing) with a polished exterior, and it costs in the range of $100 each. Both mufflers carry a lifetime warranty from Dynomax.

The Flowmaster reducers fit directly into the inlets of the mufflers.

The tailpipes are modified Torque Technologies 2 ½" OD intended for A body sedan/coupe applications. The wagon has a 116" wheelbase chassis with a bit more rear overhang, and with the tailgate in the rear, we can’t run pipes out under the rear bumper, or we get exhaust fumes drawn back into the car when driving. So, these pipes have been cut, rotated, resized, and rewelded to fit and to turn out behind the rear wheels. As a result of the wagon configuration, our testing has never been intended to qualify the fit of any of the exhaust components.

All connections are slip fit and clamped so that we can more easily replace, move, and/or disassemble the system.

Very flexible hangers are used throughout to minimize noise transmission into the body structure. The muffler hangers are the two strap variety similar to original equipment, and the tailpipe hangers are relatively long and flexible tire casing type hangers. All are set so the entire system can swing/move some but without touching any part of the body or frame. This approach means that the majority of noise heard inside the body is the exhaust sound passing out the ends of the pipes, and is not due to resonance or vibration of any part of the physical components.

May post more later on specific items mentioned above, and to describe our latest version of the wagon system. Again, we fully realize that this system may include much more time, effort, or even cost than most would want to invest, but we have invested the time and effort to look for factors that affect all exhaust systems' sound, operaton, and performance.

For a FREE summary of much of the test results, take a look at Eric D's site at address noted and select "Exhaust". Jim Hand

Pontiac Garage
http://www.wauknet.com/douthitt/


[This message has been edited by Jim Hand (edited 09-12-2000).]

[Jim Hand]

The note below is copied from the "X Pipe" thread:

Jim & Tom,
Could you please summarize the complete, present Exhaust system on the wagon that works? [I haven't subscribed to a glitter mag since 91, so this thread is it] Include status of head cross-over blockage. manifold/header type, headpipe details, X position, muffler model, length, tailpipe dia.
Thank you,
Half-Inch Stud

To Half-Inch Stud (can I just refer to you as .5"?) and to all members:

Several caveats are in order: Sound is very subjective and what sounds great to one may not be aceptable to the next person. As a good dual system makes any muffler work better, an excellent dual system causes most modern "HIPO" mufflers to perform similarly. Finally, Pontiac Dude has indicated his attention span is fairly short, so will try to keep this relatively brief. May make additional postings on some of the details.

The exhaust system that we have run on the wagon for the past several years consists of:

Home ported #64 heads that produce 10.07 CR, have peak exhaust flow of 202@28 as measured with two inch straight extension stubs on the ports, and have the crossovers filled with aluminum.

Headers are Hooker 1 ¾" primaries, 3" secondaries (Super Comp), with two inch additional length added to the left header primary tubes to equalize the average primary length between the two headers. Extensive welding and recutting to obtain optimum alignment of the openings to the head ports. Reduced the mounting hole size on front and back to assure correct alignment when installing. Have had the headers coated by Airborn Coatings - no noticeable performance difference but they look better.

Dr. Gas 3" X system from the headers to the rear just in front of the mufflers. It is located as far forward as allowed by the driveshaft safety loop. MFG states to install as far forward as possible, but the transmission, loop, and possibly other factors will dictate actual location. The 3" pipes out of the X are routed into Flowmaster 3" into 2 ½" cone reducers.

I have two sets of mufflers that we use: Dynomax 17749, which is a reverse flow unit with deflectors built in to turn the exhaust, and are packed with fiberglass. These mufflers have a body size of 4 ½" X 9 ½" and 20" length, and are 2 ½" OD side inlet, side outlet. The overall length as received is 25 ¼". This muffler is the quietest of all the performance mufflers we have tried and is used when we desire the quietest possible sound. These mufflers are available for about $40 each.

The other set we use is the Dynomax 17289, which is the Ultra Flow series. This is an identical physical package as the 17749. It is a straight through muffler with a mandrel bent pass tube of full 2 ½" diameter. The pass tube has carefully cut and sized holes to minimize any flow restrictions but to allow some sound to pass into the muffler body. The pass tube is wrapped with a layer of steel wool matting. The case is filled with special spun glass strands. The internal case has tuning chambers on both interior ends to absorb certain frequencies. The performance of these two mufflers is very close, with the ET being identical, but the MPH is improved very slightly (tenths of a MPH) with the Ultra Flow straight through muffler. The downside is that it is allows a bit more sound to pass through so they are a little louder out the pipes, but are still acceptable under all driving conditions. The Ultra Flow is a premium muffler made completely of stainless (except for the glass packing) with a polished exterior, and it costs in the range of $100 each. Both mufflers carry a lifetime warranty from Dynomax.

The Flowmaster reducers fit directly into the inlets of the mufflers.

The tailpipes are modified Torque Technologies 2 ½" OD intended for A body sedan/coupe applications. The wagon has a 116" wheelbase chassis with a bit more rear overhang, and with the tailgate in the rear, we can’t run pipes out under the rear bumper, or we get exhaust fumes drawn back into the car when driving. So, these pipes have been cut, rotated, resized, and rewelded to fit and to turn out behind the rear wheels. As a result of the wagon configuration, our testing has never been intended to qualify the fit of any of the exhaust components.

All connections are slip fit and clamped so that we can more easily replace, move, and/or disassemble the system.

Very flexible hangers are used throughout to minimize noise transmission into the body structure. The muffler hangers are the two strap variety similar to original equipment, and the tailpipe hangers are relatively long and flexible tire casing type hangers. All are set so the entire system can swing/move some but without touching any part of the body or frame. This approach means that the majority of noise heard inside the body is the exhaust sound passing out the ends of the pipes, and is not due to resonance or vibration of any part of the physical components.

May post more later on specific items mentioned above, and to describe our latest version of the wagon system. Again, we fully realize that this system may include much more time, effort, or even cost than most would want to invest, but we have invested the time and effort to look for factors that affect all exhaust systems' sound, operaton, and performance.

For a FREE summary of much of the test results, take a look at Eric D's site at address noted and select "Exhaust". Jim Hand

Pontiac Garage
http://www.wauknet.com/douthitt/


[This message has been edited by Jim Hand (edited 09-12-2000).]

[Triggerman]

JH, Pontiac Dudes attention span is short unless there is food or women involved. LOL. Best to have some combination of both....just to be sure. TM

[Jim Hand]

T.Man: Thanks for the heads up on Dude, but can't provide his needs through this board!

Headers:

We have seen serious alignment problems with the Hooker and other headers (have not had Hedman units so have no info on them). Have had Hooker units that had the center divider into one of the center ports. Have also seen headers with completely inadequate openings to cover the head port outlets. Have seen headers that all bolt holes would not align. Have seen headers that the number four bolt would not fit under the tube. And all asbestos gaskets will have a serious mismatch to the end ports, although the bolts holes are in the correct locations.

We strongly suggest that for best performance, headers be bought uncoated, trial fitted, and alignment checked. Then, after all needed realignment, port work redone, the crud dug out of the collector and primary pipes, then send the headers out for coating. We typically braze around the perimeters of the openings on the tube side of the flanges, and then recut/port on the head side as required to provide an adequately sized and centered opening to match the head port. Coated headers are about impossible to modify even if we wanted to do so. However, it does not seem logical that we would use ill fitting headers on an engine we have invested a lot of money and time for best performance!

To check actual port alignment, two methods. One is a lot of trouble, but for folks building engines, it is the best. Find an non ported head that is of no value and band saw off about one inch of the complete four hole exhaust face. Make the cut pretty much parallel to the header/manifold mounting surface. Then bolt that slice of head to the headers and you will immediately be able to see the alignment or mis-alignment of the ports/tubes by looking from the valve side of the slice. A simpler method is to use poster board, cut a piece approximately the size of a header gasket, punch holes to fit the head, install bolts to hold the poster board, and tap the edges of the exhaust ports to cut the port holes. File the inside edges of the poster board with a small fine file. Then place that poster board with the exact outline of each of your head configuration up to the appropriate header with the bolts tightly through the board. You again will be able to see if the header openings are in the correct location to collect the exhaust with no restrictions, sharp edges or other things that will lower the efficiency of the header operation.

We have found the most dependable and best fitting method of sealing the headers to the head is to make three separate gaskets for each head using Mr. Gasket asbestos gasket material. They are cut to match each port opening, then glued to the head using high temp silicone seal. The same sealer is wiped on the outer surface and allowed to dry before header installation. When ready to install the headers, the gaskets are in place, fit perfectly, and the two layers of setup silicone provide the best possible seal. Additionally, the installation looks great as there are no dirty portions of the gasket showing between the heads and headers. The bolts do need to be retightened several times, and watched as with all header gaskets.

A lot of trouble just for headers? You bet! But do you want best possible header operation, or are you satisfied with just getting the headers to bolt on? Jim Hand


[This message has been edited by Jim Hand (edited 09-12-2000).]