[Z Code 400]

Mick,

It would be easy to drop the exhaust and see if that is your problem. However, with Cliff's ability to push 500 HP through the smaller, less efficient 40 series Flowmasters and run 11.58 @ 116.39 mph, I seriously doubt you are overloading your exhaust system with 405 RWHP...Robert

[Tom Hand]

Mick,
I suspect you are right. We had another guy around here that had a similar same thing happen at the strip with his Firebird; he yanked the mufflers off that he suspected were choking the exhaust and sure enough, the car ran quicker and faster. At the power level you are at, yours will probably act the same.

When you do anything to it in the future, be sure to grab and install a good X pipe, not the cheap copies but either ones sold here from Chris at PY or from Dr. Gas or my pal Keith at Torque Tech. I found these comments about Torque Tech since you are familiar with them already. http://www.torquetechexh.com/compliments.htm

Mick, please be aware that there is a big difference in many "X"s and the right one will let you get away with slightly more restrictive mufflers with not as big a power penalty.

Regarding your comments about the mufflers you have now and how much (static) air flow they provide at the 20.3" of water pressure, I have seen enough data from talented exhaust engineers and test technicians that I agree with the power ratings. The OEM's have back pressure versus power output calculations they live by and sure as heck, the numbers we got from our tests fell right in the range they provided. So I am very comfortable agreeing with experts.

A good friend Lee A. shared this link with me, pay attention to what BigJoe says, he is one of the Engine Masters Experts.

http://www.fordmuscle.com/forums/all...agnaflows.html

I too have a four speed car and it bites to try to run back-to-back tests with it. That is why the Wagon proved to be such a cool machine to work with; deadly consistent and enough power we could do many things. And I retired my 340 four speed car since it is more fun to run an automatic mid 11 second quiet car.

[Z Code 400]

Originally Posted by Tom Hand

"Regarding your comments about the mufflers you have now and how much (static) air flow they provide at the 20.3" of water pressure, I have seen enough data from talented exhaust engineers and test technicians that I agree with the power ratings. The OEM's have back pressure versus power output calculations they live by and sure as heck, the numbers we got from our tests fell right in the range they provided. So I am very comfortable agreeing with experts....Tom

To be in agreement with the data from 'talented engineers and test technicians,' you have to completely dismiss the fact that Cliff's Ventura (as just one example) produced 500 HP through a system that, based on your theories, could only support roughly 150 HP per side. How can you, in good conscience and all honesty, blatantly ignore these facts and continue to blindly subscribe to a theory which has, at the very least in the case of Cliff's Ventura, been disproven??? Sponsorship??? You can ignore my input, because it conflicts with your accepted theory, but you cannot ignore the facts. Cliff's Ventura is just one example of several cars that I know of out here that run a chambered muffler and run the same ET and MPH uncorked or not.

Your theory is not absolute. Additionally, this is NOT a Flowmaster Vs. Pype's Vs. Magnaflow debate. It is a case of documented facts that are contrary to a simple theory. But, one certainly cannot argue that selling people on a theory is a great marketing strategy.

Big Joe???

Would that be Joe Sherman???? I raced alongside Joe and spoke to him numerous times when our RHRE Division 7 NHRA Race Team was based out of a shop on Ash Avenue in Fullerton, California in the late 1980's. At that time, Joe had a Nova with a 400 that was turning 10.30's at around 130 MPH IIRC. Joe was running dual glass packs on that car as I recall. I remember Joe as a really nice and knowledgeable guy.

I'm not selling any theory or anyone's exhaust system here. I'll leave that up to others. My opinion is always believe results over theory...Robert

[Rocky Rotella]

How fast is Cliff's car running now with a completely new exhaust system featuring straight-thru mufflers?

[Z Code 400]

Rocky,

I haven't seen an update from Cliff recently on his new Tom Hand Custom Mufflers. I am sure they are nicely made. According to Cliff, his new engine makes significantly more power than his old 500 HP version and, at that power level, he felt the 40 Series Flowmasters and 2.50" compression-bent exhaust tubing was no longer adequate for his increased power output. I would agree with Cliff on this point.

However, the main point of the debate was that Cliff's 3.00" H-pipe, 40 series, 2.50" compression bent tailpipe system supported a 500HP engine running mid 11.00's when the theory suggested such a system could not support more than 150 HP per side.

Since the 1950's, Dad has used perforated core glasspacks and thinks they are the most efficient muffler available, when correctly sized for the application. We ran glasspacks on all of our race cars, even though it was not required by rules at the time.

My point is, based on the dyno testing I have witnessed and actual testing at Bakersfield Raceway, a 425-450 HP engine, with 2.50" dual exhaust, will run no better or worse with any performance muffler, regardless of configuration. Of course, I don't expect you or Tom to consider anything I offer herein as credible, since I do not have a book yet published or any sponsors, but CarCraft conducted extensive dyno testing that showed less than 4HP and 1 lb/ft of TQ change when a chambered muffler was swapped for a straight-through variant.

Caveat Emptor...Robert

[Rocky Rotella]

The Flowmaster may have supported a 500 hp engine just as they probably would a 600 hp engine, but if either engine showed a performance increase with another muffler, then the Flowmaster simply was not up to task!

[Z Code 400]

Rocky,

I agree with you 100%. If the absence of ANY muffler netted an increase in performance, you would likewise be correct, regardless of configuration. The issue is, and still remains, the applied theories herein are considered absolutes and they are clearly flawed...Robert

[b-man]

Closed per the thread starter's request.