Just wondering? Dave D or Niebert or anyone

boostedbird

Registered User
Okay i changed my exhaust a little took out 3 small 90 degree bends in the back and made a direct exit. before I was getting about 15 inches of vaccum at idle and full boost was about 21 PSI at 6K in 1st then went to about 19 in 2nd and about 18 in 3rd and same in 4th. since I changed there is no change in vaccum still at 15 but now in 1st it goes to about 19 PSI 2nd 18PSI 3rd and 4th goes to about 17.5 PSI what would cause this??? Nothing else was changed except I replaced the single 3 in inlet 3 inch outlet magnaflow with a single 3 in inlet dual 2 1/2 outlet super 40 flowmaster sounds sssssoooooo much better. I'm gunna see if my friend will video it and then I will post the new look and sound. It sounds just like a V8 low rumble and nice power sound!
 
That's completely normal. You removed some of the restrictions in the exhaust, which lowered your boost. Boost is simply a measure of the pressure in the intake manifold. By removing some of the restrictions in the exhaust, air has an "easier" time traveling through your engine.

Even though you're now seeing less boost, the engine should be making more power.

-Rod
 
And I figured as much But if it is making more power its not much more but hey I guess I'll take anything haha. Just was curious as too what it could be cause the old set up was not restrictive but it made its way around the gas tank through a mandrel 3 inch under the axle made an almost 90 degree into a long magnaflow muffler and then turned 90 degrees toward the rear of the car and then another 90 degree downturn to the ground. The new one goes through the same 3 inch mandrel around tank but then just goes straight into a 3inch super 40 flowmaster and then straight out the dual 2 and 1/2 outlets. The flowmaster is about 6 inches shorter than the magnaflow and has about a 3 inch bigger case the super 40 has a very big case for better flow.
 
Yes you got rid of restriction somehow with your exhaust.

However testing has proven magnaflows to produce LESS backpressure the flowmasters..So its in the exhaust and not the muffler choice
 
Chris,

Ditto on what the other guys said. I'm guessing you made the changes to create a less restrictive exhaust system, and it sounds like you succeded.

David
 
racecougar said:
That's completely normal. You removed some of the restrictions in the exhaust, which lowered your boost. Boost is simply a measure of the pressure in the intake manifold. By removing some of the restrictions in the exhaust, air has an "easier" time traveling through your engine.

Even though you're now seeing less boost, the engine should be making more power.

-Rod
Absolutely. All I did was replace the stock down tubes and resonator and it added 35 rhp on the dyno.

Ira
 
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DamonSlowpokeBaumann said:
Yes you got rid of restriction somehow with your exhaust.

However testing has proven magnaflows to produce LESS backpressure the flowmasters..So its in the exhaust and not the muffler choice

I agree Damon and thats what i have been told alot is that the magna flows better than the flowmaster but if you look at their super 40 it acually is a very good flowing muffler.
 
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