[Cliff R]

"So, how do you explain Cliff Ruggles running compression-bent tubing, a 'H'-pipe and 40 series Blowmasters and 2.50" tailpipes and running 11,50's?????"

Robert, that's easy, the engine we were using at that time made 514hp and 600ft lbs torque. I made enough torque to give you a nose-bleed on hard launches, and would run mid-11's shifting at 5000rpm's. I didn't need or use high rpm's to make good runs at the track. I could shift straight from 1st to 3rd gear, and only slow up .02-.03 seconds at the same MPH as the previous run!

I doubt if the exhaust system had much effect on the ET's with that engine, as we used the massive torque production of the engine to run good times at the track.

Our new engine is more HP oriented, and we immediately noticed the Flowmasters and 2.5 non mandrel bent tailpipes weren't going to cut it. The new engine enjoys running up near 6000rpm's, so we went to 3" straight thru custom built mufflers and 3" turn downs for now.

What amazed me the most about the straight thru mufflers vs the Flowmasters, is that they are quieter. I was expecting the new mufflers to be nearly as loud as open headers, being straight thru with no tailpipes. Not so, they are much quieter, and not "raspy" like the Flowmaster mufflers. I can actually hear the fuel pump running with the new mufflers, sitting at idle at stoplights, etc......Cliff

[Z Code 400]

Originally Posted by Cliff R

"I doubt if the exhaust system had much effect on the ET's with that engine, as we used the massive torque production of the engine to run good times at the track.......Cliff"

Thanks, Cliff....

I have always been impressed with your car....Robert

[Z Code 400]

Originally Posted by Cliff R

"Robert, that's easy, the engine we were using at that time made 514hp and 600ft lbs torque. I made enough torque to give you a nose-bleed on hard launches, and would run mid-11's shifting at 5000rpm's. I didn't need or use high rpm's to make good runs at the track. I could shift straight from 1st to 3rd gear, and only slow up .02-.03 seconds at the same MPH as the previous run!

I doubt if the exhaust system had much effect on the ET's with that engine, as we used the massive torque production of the engine to run good times at the track...Cliff"

Cliff,

That's exactly what gets me with all this talk about restriction and suspicious horsepower gains.

You have proven that with an obviously inferior exhaust system, consisting of an H-pipe, dual Flowmasters and compression-bent, 2.50" tailpipes, that system was adequate to support 514 horsepower and 600lbs/ft of torque and our testing of the Flowmaster Crossflow, on a 406 CID engine making over 450 HP @ 6000 rpm, never pushed the system into a pressure condition, as verified by using a Snap-On Vantage and dual pressure transducers. Why??? Because both systems were adequate for the CID and HP production levels!!!

Yes, the Pype's Crossflow is likely quieter than the Flowmaster and I have personally verified that it affords more clearance for suspension movement and rear disc brakes than the Flowmaster. It's stainless steel construction is also a nice advantage.

The merits of the Pype's Crossflow are clearly defined. a 20 HP gain and 2/10ths of a second on the average car is not. It IS a great system, but unlikely to afford any benefits other than those previously outlined. While anything is possible, the greatest percentage of average enthusiasts, that choose the Pype's Crossflow, will gain a great looking, great sounding exhaust system, constructed of stainless steel. Ok...Cool.

At power levels of 450 and less, with streetable engines, I doubt that any 2.50" system, whether it be H-pipe, X-pipe or 'brand-x' muffler configuration would offer any advantage over any other, regardless of who made it. I see a lot of guys locally who upgrade from manifolds to headers and from 2.250" pipes to 2.500" and any 'brand x' muffler (including Flowmaster) that you can name and then announce to everyone how much HP and TQ the muffler swap gave them.

Let's sell this system by it's previously mentioned, real-world benefits (suspension clearance, sound and stainless steel construction) rather than banking everything on what is probably a very isolated case of horsepower gain on a handful of cars.

A fellow here in Visalia pulled a 2.50" dual Flowmaster system off a first-gen Camaro in favor of a 2.50" Magnaflow system. The car actually did pick up a few HP and lbs/ft of TQ on the dyno, so everyone was satisfied that the Flowmasters were junk. The old exhaust system was given to a mutual friend, who installed it on another Camaro.

He called me to come over one night and asked me to look up into the pipes at the collector flange. Both headpipes had been cut with a chopsaw when fitted and there was a thin steel 'wall' of metal that extended all the way across the tubing, leaving less than a 2.0" area for gasses to flow past. Nobody ever looked to see this when they welded it up!!!!!!

I loaned him a die grinder, with a long carbide burr, so he could trim the flashing out of the tubing. Tell me that didn't create a flow restriction.

These are just a few of the variables that you can encounter that nobody talks about.

If you are shopping for horsepower, don't spend money twice. Caveat Emptor....Robert

[Cliff R]

Robert, if you follow the testing Jim Hand and his son Tom have done with mufflers and exhaust systems, you will notice that when you get back past the muffler(s), smaller pipes are not a big restriction, if any restriction at all in the system.

I'm far from an expert in this area, so I don't post much about it.

I can tell you for certain, we saw a HUGE gain with my car going from a 2.5" "H" pipe assembly (non mandrel bent) up to a 3" system, using the same mufflers and tail pipes.

At that time my car wasn't running nearly as fast as it is now, and only making about 455hp. It was one of the things I did to the car along the road to mid-11's, that delivered the "best bang for the buck", falling 2nd to the sumped fuel tank, electric pump, and 8AN lines/fittings everywhere.

You have to consider that when the hot exhaust gasses leave the cylinder heads, they are up near 1000-1100 degrees, yet you can put your hand at the exit of the tailpipes and it doesn't instantly get melted down. This clearly shows how quickly the gasses condense and cool moving back through the exhaust system.

Giving these engines larger head pipes, especially X pipe systems, provides more capacity for this cooling/condensing to occur. The X and H pipes also provide dual paths for flow, and I would imagine that allowing one side to see the other side helps with reversion, or has some positive effect on the pulses bouncing around inside the pipes, etc?

Like I said, I'm no expert on this subject, we just know that large head pipes and X and H systems work very well. I've ALWAYS used "H" pipe systems, dating back over 30 years, even on some of my street driven tow vehicles that used gasoline engines. Of course I've never had any way to do any back to back testing for ET, MPH, dyno etc, but have always noticed that connecting both sides together has positive results, when it comes to noise level(s), or getting rid of high pitched "buzzing" at specific rpms, etc.

As mentioned above, what amazes me the most is that my custom made straight through 3" mufflers are much quieter than the chambered Flowmasters, with no reasonance or specific "buzzing" at any rpm's, etc. I would never go back to Flowmasters for any reason, after having used these new mufflers. I LOVE the sound, and the sound level, and there is no restriction on the system anyplace......Cliff

[pontiacstogo]

On a more subjective note;

I have run the Flowmaster system on my 74 T/A since I got it back on the road 5 or 6 years ago. I've never been happy with the sound of it, particularly at idle/low engine speeds. It sounds a little better at WOT, but that's about the only time it does. At any other engine speed/throttle opening it's pretty 'droney' - in fact, at idle it almost sounds like the entire system has leaks (it doesn't). Some folks have told me that any 2.5 inch system will drone given my stock engine combo and that may be true.

The complete Flowmaster system sits behind a 100% bone stock, low comp. 400 T/A running stock log manifolds mated to Pype's downtubes. I had to replace the crossflow muffler recently. The new one that went on the car during the restoration started to rattle badly and I eventually traced the problem to the heat shield spot welds. Two of them had broken through the outer case of the muffler allowing it to leak, and allowing the heat shield to rattle against the case. I toyed with the idea of replacing the entire system with something else instead of putting on a replacement Flowmaster muffler but I didn't.

Aside from the sound, and the fact that I had to replace the muffler once already, it's an OK system. I don't have any of the clearance issues described in other posts and I was able to have the entire system fitted using stock mounting points (without any modifications to the car required).

[ta man]

Alot of the drone and resonance issues occur with the restrictions or baffles in the mufflers.If you have a straight through style muffler like a ultraflow you don't have any restriction to the exhaust flow so no drone.I agree with Cliff on the smaller tailpipes >my car for example runs almost 115mph through 2 1/2" inch tailpipes and 2 1/2 inch ultraflow mufflers but utilizes larger 3 inch x headpipes.

[73ta]

"The Flowmaster WILL NOT work with rear disc brakes on a Second Generation car PERIOD. I'll send you the photos if you like to prove it."


I would have to say that is not true as I have been running that combo on my 73 TA,(rear disc), since the flowmaster system became available, probably for at least 15 years with minor tweaks!

[Z Code 400]

Originally Posted by 73ta

"The Flowmaster WILL NOT work with rear disc brakes on a Second Generation car PERIOD. I'll send you the photos if you like to prove it."


I would have to say that is not true as I have been running that combo on my 73 TA,(rear disc), since the flowmaster system became available, probably for at least 15 years with minor tweaks!

I have a 1979 T/A disc brake 10-bolt under my car. The brake hose bracket on the left axle tube will impact the left inlet pipe, even under minor bumps. The brake line runs across the front of the axle tube on the right side and also causes interference.

Yes, you can beat the pipes flat and make it fit, or re-route the brake lines, but why bother????

Resonance,

Most of the time you will find the 'resonance' caused by rigid exhaust mounting. I have 'fixed' several friend's cars with properly hung pipes and new rubber isolators. If the system is in a bind, it will vibrate and rattle....Robert

[M&M]

I'm finding this fitment issue very interesting. I have the Flowmaster system on my '75 T/A, and the rearend nails the muffler's inlet pipes whenever the suspension moves up. That is why I'm thinking of switching to the Pypes system. And I don't mean the rearend taps the pypes, it knocks the heck out of them. Caused the brackets made on the exhaust pipes under the passenger seat to dent the floor. I've changed rear springs, (Year One), shocks, (Edelbrock, then Bilstiens), still the same results.

Some of you guys have had no trouble at all.

What up?

Mack

[Z Code 400]

M&M,

I hung the system in the stock crossflow mounts. I didn't drill the floorpan like Flowmaster suggests. I took a pretty good bump a few months ago and the axle struck the right inlet pipe, knocking a pretty good dent in it.

My rear suspension sits at stock height with 255/60/15's and Koni's too.....Robert

[pontiacstogo]

Originally Posted by M&M

Caused the brackets made on the exhaust pipes under the passenger seat to dent the floor.

Isn't the 75 and later floor different in this area (because of the cat) or are you meaning the rear seat?

The shop that fitted my system originally (and did the replacement muffler) tilted the muffler back at the bottom - the clearance above the rear differential is close, but it never touches (my springs and shocks are stock). They used the stock 74 hangers with reproduction mounts on the muffler and welded steel rod on the tailpipes to extend up to the stock tailpipe hangers.

[M&M]

[QUOTE=pontiacstogo;3854401]Isn't the 75 and later floor different in this area (because of the cat) or are you meaning the rear seat?



I don't know about changes made for the cat, but mine orginally was under the driver's floor, the seat/leg area. No mater tho, you are absolutely correct, I meant to say the brackets under the rear seat, not the passenger's. My appoligies. Thanks for pointing that out.


Back to the Pypes system,,,,,,, I am running a set to d-port ram air exhaust manifolds. One side has a two bolt flange, one side has a three bolt flange. When looking at Pypes' web site, I'm thinking I want the downpipes #DGA20S23 with a two bolt, and a three bolt, flange. When I look at my Performance Years cat, I cannot find that set. I see the HO/RA pipes as #DGA20S, which Pypes's site says has no flanges. Would my flanges slide over the new 2 1/2 pipes? What am I missing?

As always, my thanks to everybody.
Mack

[Z Code 400]

There is so much B.S. out there with respect to exhaust systems these days. One of the most blatant cases of 'Marketing B.S.' is the knowledge that a 2.50" pipe will only flow about 500cfm, yet Dynomax advertises it's 2.50" muffler as flowing 1100cfm. Dad and I have been discussing the trend towards straight-through mufflers, which we both laugh about, since it is simply a throw-back to 70 year old glasspack technology that everyone raves about as being the 'cutting edge' of exhaust technology.

I went over to Da'ds today and discovered he had been working on a prototype muffler for my car. One of the flaws that Dad pointed out is when you allow sound to escape into the case, you also allow gas to escape out of the flow path too, because you cannot separate the two. Dad believes that it is critical to provide the sound flow path with an avenue to re-enter the exhaust gas path, rather than just allow it to accuumulate in the case with no outlet.

Dad began with a true X junction struck from T304 Stainless tubing that has oval ports placed in strategic locations. When placed into the handmade case, four distinct sound chambers are created. Triangle shaped inserts are fitted into these four chambers and an oval, trumpet-shaped communication tubes feed sound/gas into each chamber and provides and exit path back into the exhaust stream. The upper tubes will serve as inlets and the lower tubes will serve as outlets.

Dad hasn't decided on where the packing will be placed, but we are using Kevlar panels discarded from outdated bullet-proff vests, cut into long, thin strips. His theory is that a perforated 'diamond' would be placed in each chamber, filled with Kevlar 'hair' and then welded to the case.

This allows sound and gas a free path around the diamond, with no disruption in flow a sound absorbtion effect without just stuffing the case full of OCF and pressurizing it.

Dad works at his own pace, so I don't have a completion date, but I am eager to try this crossflow on my Formula.

More to come...Robert

[crustysarge]

I had the Flowmaster 17104 on my 77 TA for about 22 years. I changed the muffler once a few yaers back as it rotted at the bottom, it cost half what the entire system did...About 6 months ago I installed the Pypes system and it is quieter and fits better.

The 17104 was really "droney" but did sound good, but loud. I also had the right side inlet pipe hit and ding the pipe pretty good. The Pypes has not hit and has much better clearance. I fabbed some rear supports and it was a bit of a PITA to install alone but I like it.

IMO, Pypes. Get some band clamps.

[Tom Hand]

For folks who might want an X inside their muffler

17553 - Dynomax Ultra-Flo X Mufflers

This innovative muffler design features a large internal pass tube with large perforations to maximize sound absorption yet retain ultra-smooth flow. Sound deadening is handled by stainless steel mesh along with continuous roving fiberglass , heat resistant to 1500 degrees, that won't blow out.

Features:
# Unique 3" OD x-pipe design perforated flow tubes inside
# Full arc weld construction
# 16 gauge stainless steel material
# Use of high temperature OCF roving fiberglass for sound attenuation

Ultra-Flo X Muffler Dimensions:
# Body Height: 4-1/2"
# Body Width: 9-3/4"
# Body length: 20"
# Overall Length: 25"

View in Current Catalog

Complete list of Dynomax Ultra-Flo X Mufflers


Dynomax #289-17553

# Ultra-Flo X MUffler2-1/2" I.D. Dual Inlet/Dual Outlet
# 1300 cfm Flow Rate

[Z Code 400]

Not a bad product, but is it faithfully represented???? I find it fascinating that, based on Jim Hand's (and other's) testing, a 2.50" pipe can flow a maximum around 500cfm, yet this 2.50" muffler can magically flow 1300cfm.

Dad's design is far more forward-thinking....Robert

P.S. Try this....the next time you are testing a large-case muffler that has 'zero backpressure', take a pressure reading in the case itself. What you see might surprise you...Robert

[Tom Hand]

Searching for some more info to share, I came across this neat shot of most of the mufflers we tested. After testing and shooting photographs of them, they were given away at a St. Louis meeting sponsored by Classical Pontiac. Some were sent back, and we had to borrow Flowmasters from another source but they too went back. Here too is the shot of the crossflow recording/testing set-up we used so we could test so many so quickly. This shot was taken to show what it looked like when we were running and recording the X-crossover portion of the muffler CD we made.

We also borrowed lots of headers to shoot photos of (for the book). Some we were told to keep around for future usage but we promised we would never sell or make money from them.

Just recently, the last two sets of headers were given away (or promised) to fellow Pontiac folks. We still have one set of headers,custom made from 409 st. st. to fit round port heads, they have 1.75" primaries. We also still have a few individual muffler cutaways to use for technical reasons or photographs.

Testing and sharing information has lots of benefits. This is sort of the same deal that Chris made with us when we got to work with PYPES on the crossflow. Bob C. and I and my brother mocked the parts up and once they were finished, in exchange, Bob C got one of the first set of PYPES-made pipes. All of us (Chris, Bob C, my brother, and I) got a lot of satisfaction seeing them go into production and get used so successfully by so many.

Like many others of you do for so many people in this Pontiac community, we found that doing things for the manufacturers and reporting about them fairly and with the goal of not making money but sharing, turns out to be the best deal for all!

[Z Code 400]

The bends look pretty nice on that tubing. Seems like Pype's is turning out some pretty good quality control....Robert

[Tom Hand]

Hey Mack, did you get all the info you needed? We got somewhat off track with your post......
Tom

[M&M]

Originally Posted by Tom Hand

Hey Mack, did you get all the info you needed? We got somewhat off track with your post......
Tom

Hi Tom. Thanks for asking. Yeah, things did get a might off track.

I have decided to go on and switch over to the Pypes system, but I'm confused about the downpipes.

I am running a set of d-port ram air exhaust manifolds on a 455 in a '75 T/A. One side has a two bolt flange, one side has a three bolt flange. When looking at Pypes' web site, I'm thinking I want the downpipes #DGA20S23 with a two bolt, and a three bolt, flange. When I look at my Performance Years cat, I cannot find that set. I see the HO/RA pipes as #DGA20S, which Pypes's site says has no flanges. I really don't think my flanges will fit over a 2 1/2 pipe. What am I missing?

I'm wanting to do the full monty,,,, from the downpipes all the way to the exhaust tips, and want to be sure to order all the correct stuff.

Thanks again
Mack