Max RPM for my new Exhaust system?

-
1968FormulaS340

1968FormulaS340

Well-Known Member
Joined
Aug 24, 2005
Messages
11,394
Reaction score
700
Location
St. Helens Oregon
Wondering after what RPM am I just wasting my time. 340 manifolds 2863549RH and 2863553LH (the good ones) backed by a TTI 2.5” X-pipe system with Dynomax ultra flows. I would guess that I no longer need my 8000 rpm limiter and could step down to something lower.
 
1968FormulaS340 said:
Wondering after what RPM am I just wasting my time. 340 manifolds 2863549RH and 2863553LH (the good ones) backed by a TTI 2.5” X-pipe system with Dynomax ultra flows. I would guess that I no longer need my 8000 rpm limiter and could step down to something lower.
Click to expand...

8000. You must like living on the edge. Just call me gramps. LOL.
 
How do those Dynomax ultra flows sound? Are they as loud as flowmasters 40s, or 50's??? Can you talk in the car while driving ok?
I'm interested in the dynomax Ultra's for the performance but don't want to piss off my neighbors when I leave for work every day.
 
What heads, cam, and valve springs are you running on your combo? Len, I'm with you. I'm way too old to live that close to a sudden sharp pain in the area of my wallet pocket. :)
 
The engine was made to spin that high and has 17 years but only 2000 miles on the hugely expensive rebuild. I was told not to expect much more than about 3000 reliable miles out of the springs.

A not very detailed combo is, Crower solid roller, pro ported and flowed X-heads, balanced and lightened bottom end. #s matching block and heads.
 
ProStreetDuster said:
How do those Dynomax ultra flows sound? Are they as loud as flowmasters 40s, or 50's??? Can you talk in the car while driving ok?
I'm interested in the dynomax Ultra's for the performance but don't want to piss off my neighbors when I leave for work every day.
Click to expand...

I don’t know for sure what the flowmasters sound like so it’s hard for me to compare. But I can tell you how the ultra flows sound. Idle sound quality is nice and in no way overly loud (about the same as the super turbos I replaced). Just off idle and or at a low RPM load (25 mph in town in 3rd or 4th) the sound comes up and is very deep (this is the worst area for these mufflers as far as sound control). As the RPMs come up the sound goes down and smoothes out. With a full interior conversation is not a problem on say a highway drive and I am running 3.91 gears.

In short. At idle muscle car quiet, low RPM under load much louder, midrange RPM driving smooth and deep with a very acceptable sound level increasing slowly and progressively as the engine increases in RPM.
 
I agree I had those on my mach 1 and loved the sound. Nice and quiet at cruise speeds, but when the rpm's got low or under WOT nice muscular sound. I took these over the 40 and 50 series flows due to the quieter ride to work and back.
 
Like was said..The exh isnt really the wall you'll hit..It's valve springs/lifters/carb. If those are all good enough to support it, the exh will too. My guess is, witht he manifolds, it wont make much power up there, but it should get there. I set my chips at about 300rpm higher than my trap rpm at the track. If you dont need to rev it, dont. That way, it's safe if something breaks. The motor winds generally a couple hundred rpm past the limiter under acceleration because of inertia. (like if you spit the driveshaft at the 1000' mark, and all of a sudden the motor free revs..the limiter comes on, bu tinertia will continue spinning fast for a second or so..)
 
OldVart said:
What heads, cam, and valve springs are you running on your combo? Len, I'm with you. I'm way too old to live that close to a sudden sharp pain in the area of my wallet pocket. :)
Click to expand...

I'm running a 'Scott Brown' flat solid about .575 lift and 265 degree duration @.050". Pretty unremarkable. Dual springs sent with the cam (read no name). Think Scott said they have 150lbs. seat and 380 open. The heads are econno W2's ported by me.
 
1968FormulaS340 said:
I don’t know for sure what the flowmasters sound like so it’s hard for me to compare. But I can tell you how the ultra flows sound. Idle sound quality is nice and in no way overly loud (about the same as the super turbos I replaced). Just off idle and or at a low RPM load (25 mph in town in 3rd or 4th) the sound comes up and is very deep (this is the worst area for these mufflers as far as sound control). As the RPMs come up the sound goes down and smoothes out. With a full interior conversation is not a problem on say a highway drive and I am running 3.91 gears.

In short. At idle muscle car quiet, low RPM under load much louder, midrange RPM driving smooth and deep with a very acceptable sound level increasing slowly and progressively as the engine increases in RPM.
Click to expand...

Thanks for the info, looks like I'll be getting these.
 
You must log in or register to reply here.
-

Back
Top