[Tom Hand]

Check out these shots of the new Dynomax VT's modified to fit F-bodies. Three inch in and out, offset-offset, 19" overall. It is a direct replacement for the Dynomax Welded 17229 mufflers created about ten years ago for F-bodies.

We should get sound level data and subjective resonation opinions as soon as I get them delivered and they are installed on a 69 Firebird.

[lamans71]

Keep us updated, very interested as I was looking at these for my 71 LeMans.

[Tom Hand]

http://forums.maxperformanceinc.com/...d.php?t=632802

Lamans, at the end of this string, I give some data on another set we played with.

These ones I mentioned for the F-Body will work also for the A-body cars and you need not shorten the inlet and outlet bushings. For 3" pipe-equipped cars, you only need expand the bushings to make them work right now. Hopefully Walker will do it for us soon ..
Tom

[lamans71]

Thanks for the link Tom, very helpfull. My 71 conv has way too much drone with the top down; and why would you have the top up. I just bought this car and it has headers, 3" system w/H-pipe, and glass packs. I was thinking about going with a flowmaster muffler but was told that thay hurt flow quite abit, and that these dynomax mufflers are less restrictive. The system I have now sounds great but as I said just too much drone while crusing at 40-65mph. And while I will not drive it much right now due to the extreme summer heat I will during the Fall/Winter/Spring which is the prime time weather here.

[rohrt]

Originally Posted by Tom Hand

Check out these shots of the new Dynomax VT's modified to fit F-bodies. Three inch in and out, offset-offset, 19" overall. It is a direct replacement for the Dynomax Welded 17229 mufflers created about ten years ago for F-bodies.

We should get sound level data and subjective resonation opinions as soon as I get them delivered and they are installed on a 69 Firebird.

Will a 19" muffler fit? I thoght 14" was about the limit? Would love to see some pics when your done.

[Tom Hand]

Muffler body is 14" with 5" on traditional ones. This one has a muffler body of about 16.5 with bushings of about ~1.375" each. Should fit right on and in but we will know for sure later this week. Flowmasters are typically 17" body for this car and they fit under the chassis floor just fine so this should be good too.
Tom

[First Bird]

Count me in for a pair.

[amcmike]

It be nice to see some dB (idle/cruise/WOT) and backpressure or power comparisons between the 17229 and the VT.

[Tom Hand]

Exactly what is planned.
The backpressure is much tougher to measure as these do not act like normal mufflers. The good thing is once they are wide open, the back pressure is very stable and relatively low.

[arrowem]

Any info yet?

[Tom Hand]

Actually, it is in work right now on a Firebird in Illinois. Our dear friend Mike Noun has been breaking his back and enduring all sorts of heat and misery swapping mufflers and pipes. I am sorry that it took us a bit longer to get started because we had to round up a set of current 17229 mufflers to get a fair comparison.

As he gets time, I believe Mike will report data he feels is applicable.
Tom

[Tom Hand]

Mike is done and one of these days soon, after he recovers from being sore and in the extreme heat for so long, he will share data. In the meantime, I wanted to add that I just got to follow my brother-in-law's 68 360 Cuda that we installed them on and man, is it quiet during normal driving. He has no resonation inside and it is tame outside until you wail on it. Really a sweet deal.

[MikeNoun]

Just finished with the muffler comparison, and I can say I am VERY impressed with the Dynomax VT's.

Just a quick background:

Test Car......... : 1969 Firebird
Engine............ : Pontiac 455
Camshaft....... : Comp Cams 305H flat tappet
Headers ......... : Indian Adventures Headers, 2" primary, 3.5" collectors, tapered reducers
Exhaust.......... : 3" pipes, Dr. Gas X-pipe, 3" tailpipes exit behind rear wheelwells (stock)
Performance... : 11.6's @ 116 mph - full exhaust, street tires

Dynomax #17229 Ultra Flow Welded vs. Dynomax #17959 Valve Technology VT
Both mufflers were 3" offset/offset.


********* Test #1 - Readings taken 10' behind tailpipes @ 800 rpm *************


Dynomax 17229
------------------
800 rpm - 84 db
2000 rpm - 93 db
3500 rpm - 105 db


Dynomax VT's
-----------------
800 rpm - 81 db
2000 rpm - 87 db
3500 rpm - 106 db


*********** Test #2 - Readings taken 10' behind tailpipes @ 800 rpm ************


Dynomax 17229 w/18" long Dynomax bullet mufflers
----------------------------------------------------------
800 rpm - 82 db
2000 rpm - 90 db
3500 rpm - 102 db


Dynomax VT's w/18" long Dynomax bullet mufflers
----------------------------- --------------------------
800 rpm - 78 db
2000 rpm - 84 db
3500 rpm - 103 db


********** Test #3 - DB Meter placed inside interior, on center console, all windows closed ************


Dynomax 17229
------------------
800 rpm - 77 db


Dynomax VT's
-------------------
800 rpm - 75 db


*********** Test #4 - DB Meter placed inside interior, on center console, all windows closed ***************


Dynomax 17229 w/18" long bullet mufflers
------------------------------------------------
800 rpm - 74 db


Dynomax VT's w/18" long Dynomax bullet mufflers
-------------------------------------------------------
800 rpm - 72 db


Accelerating away from a stoplight, under light load, the quietest mufflers by far were the VT's. The VT's actually had a slight hissing sound, almost like a stock GM muffler! While the Dynomax VT's were indeed quieter than the Ultra Flow Welded 17229's, they still retain some of that low end rumble we like to hear on our old cars. The most noticeable difference between the Dynomax VT's and the Dynomax Ultra Flow Welded mufflers are when you're driving down the road, the interior resonance is almost completely non-existent with the VT's.

Very happy with the results! While I did not conduct dragstrip tests or WOT sound level tests, it appears that when the VT valve opens under heavy load, they have the same straight-through unrestricted design as the Ultra Flow Welded. Under full throttle, both the VT's and the Ultra Flow Welded mufflers sound identical.

[grandville455]

Where were the bullet mufflers placed near the tail pipes?

[petethewicked]

old link, but i'm doing my exhaust. so, bump

[petethewicked]

how do they fit? can they be tucked way up? I'm going to run in to clearence issues

[petethewicked]

update they make 14 inch cast for us now...
also mike nouns part numbers are wrong on what he tested

17959 is a 2.5 in 2.5 out.. not a 3 inch muffler.. fyi