Question on tuning after adding race mufflers

Posted By: Dart Racer

Question on tuning after adding race mufflers - 06/02/11 06:37 PM

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers. Any thoughts on whether I will need to change the tune with these. Car is currently just a tad on the lean side at sea level.

Posted By: SLOW67

Re: Question on tuning after adding race mufflers - 06/02/11 07:11 PM

I went from full exhaust to bullets on the mustang street car I used to have and saw no noticeable difference on my A/F gauges(had a digital sweep and a milivolt readout gauge) I would say maybe a .050 milivolt change at full throttle. This being an injected car it may have made up the difference itself idk. Just my

Posted By: MR_P_BODY

Re: Question on tuning after adding race mufflers - 06/02/11 08:20 PM

Quote:

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers. Any thoughts on whether I will need to change the tune with these. Car is currently just a tad on the lean side at sea level.

If your talking a big thru flow header muffler you MIGHT
end up leaning 1 jet size... more restrictive will
require more reduction on jetting... didnt really need
to change timing.... still jet for max MPH

Posted By: Dart Racer

Re: Question on tuning after adding race mufflers - 06/02/11 08:43 PM

Thanks; since I am already on the lean edge, sounds like it should be just right.

Posted By: Cab_Burge

Re: Question on tuning after adding race mufflers - 06/02/11 08:46 PM

Quote:

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers. Any thoughts on whether I will need to change the tune with these. Car is currently just a tad on the lean side at sea level.

Itreid a set of 3.5 Bullets on my 1969 Dart GTS 440 powered bracket car years ago at LACR, back to back versus open headers to the Bullets 20 minutes later that car slowed down .110 and 1 MPH adding the bullets versu straight out of the 2 inch Hoker A body fenderwell headers

On my street Duster, its a lot faster than the dart was, I use a set of Mganaflow 3 inch x 14 inch lon oveals mounted at the rear bumper and the car only changes .04 and .12 MPH in the 1/8 mile track at madras, OR when I switch from the full exhaust to the open headers, same headers that were on the Dart

I highly recommend the straight thruough Magnaflows versus the Bullets based on my personel experiences

Posted By: MR_P_BODY

Re: Question on tuning after adding race mufflers - 06/02/11 09:10 PM

Quote:

Quote:

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers. Any thoughts on whether I will need to change the tune with these. Car is currently just a tad on the lean side at sea level.

Itreid a set of 3.5 Bullets on my 1969 Dart GTS 440 powered bracket car years ago at LACR, back to back versus open headers to the Bullets 20 minutes later that car slowed down .110 and 1 MPH adding the bullets versu straight out of the 2 inch Hoker A body fenderwell headers On my street Duster, its a lot faster than the dart was, I use a set of Mganaflow 3 inch x 14 inch lon oveals mounted at the rear bumper and the car only changes .04 and .12 MPH in the 1/8 mile track at madras, OR when I switch from the full exhaust to the open headers, same headers that were on the Dart I highly recommend the straight thruough Magnaflows versus the Bullets based on my personel experiences

Did you do any jetting to see what they were really
worth or did you just put them on and ran it

Posted By: an8sec70cuda

Re: Question on tuning after adding race mufflers - 06/02/11 09:29 PM

4" bullets on my 9 sec 800+ hp hemi run the same as open headers.

Posted By: Cab_Burge

Re: Question on tuning after adding race mufflers - 06/05/11 07:04 AM

Quote:

Quote:

Quote:

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers.� Any thoughts on whether I will need to change the tune with these.� Car is currently just a tad on the lean side at sea level.

Itreid a set of 3.5 Bullets on my 1969 Dart GTS 440 powered bracket car years ago at LACR, back to back versus open headers to the Bullets 20 minutes later that car slowed down .110 and 1 MPH adding the bullets versu straight out of the 2 inch Hoker A body fenderwell headers On my street Duster, its a lot faster than the dart was, I use a set of Mganaflow 3 inch x 14 inch lon oveals mounted at the rear bumper and the car only changes .04 and .12 MPH in the 1/8 mile track at madras, OR when I switch from the full exhaust to the open headers, same headers that were on the Dart I highly recommend the straight thruough Magnaflows versus the Bullets based on my personel experiences�

Did you do any jetting to see what they were reallyworth or did you just put them on and ran it�

put them on and ran it, it was late in the day , after the 4th round so that was the last run of the day for me. They shut time only off right after my run

Posted By: moparacer

Re: Question on tuning after adding race mufflers - 06/05/11 07:09 AM

Just ran quicker with my 3 1/2 bullets and side exit exhasut tonight.

5.96 pass

I am alky injected though. Might change a carb tune some.

Posted By: Locomotion

Re: Question on tuning after adding race mufflers - 06/05/11 11:57 AM

Quote:

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers. Any thoughts on whether I will need to change the tune with these. Car is currently just a tad on the lean side at sea level.

I installed a TTI X-pipe and 3" Dynomax Ultraflow mufflers (the big, oval ones) on my car and picked up over open headers. But that was probably due to the X-pipe. I figure if the mufflers are big enough and not restrictive for your particular combo, you won't slow down.

I believe I did jet down a number or two and also had to take out 60lbs from elsewhere in the car to compensate for the weight of the system. The jetting may have also been influenced by the X-pipe rather than the mufflers.

I may try the smaller, lighter bullet style some time in the future.

Posted By: Quicktree

Re: Question on tuning after adding race mufflers - 06/05/11 12:06 PM

Quote:

Quote:

PSCA just added a muffler requirement, and so I'll be installing the Dynomax Bullet race mufflers. Any thoughts on whether I will need to change the tune with these. Car is currently just a tad on the lean side at sea level.

I installed a TTI X-pipe and 3" Dynomax Ultraflow mufflers (the big, oval ones) on my car and picked up over open headers. But that was probably due to the X-pipe. I figure if the mufflers are big enough and not restrictive for your particular combo, you won't slow down.

I believe I did jet down a number or two and also had to take out 60lbs from elsewhere in the car to compensate for the weight of the system. The jetting may have also been influenced by the X-pipe rather than the mufflers.

I may try the smaller, lighter bullet style some time in the future.

Myron do you have a pic of your exhaust system by any chance?

Posted By: Locomotion

Re: Question on tuning after adding race mufflers - 06/05/11 12:55 PM

Quote:

Myron do you have a pic of your exhaust system by any chance?

Tony,

Sorry, I don't. But it took a good bit of trimming bit-by-bit to get it all fited/lined up. The "X" is directly below the front u-joint and I had to slightly dimple it for driveshaft loop clearance. Rear hangers are off of the rear seat belt bolt holes and is where the mufflers are the end of the system, just in front of the rear end housing.

I believe I heard it's best to have the "X" as close as possible to the collectors.

But, for what it's worth, here is a TTI site pic:

WOW, I don't know how it ended up THAT big!

But the X-pipe section I got in my kit was a lot nicer/cleaner/smoother than the one shown. Not cut-up/rewelded. I was just trimming the ends of the "X" and adapter pipes bit-by-bit to sneak up on the best alignment.

Posted By: Quicktree

Re: Question on tuning after adding race mufflers - 06/05/11 01:24 PM

thanks that is what I was looking for