okkk guys help me out

mrd11387 · **okkk guys help me out**

oooooookkkkkkkkkk i dont know what to do.....people told me to put dynomax mufflers on my car because it sounds good,but i would have to have a muffler shop run pipes...here is the problem, muffler shops bend them and the flow is restricted and it loses backpressure.....i was thinking about getting the flowmaster cat back system since it comes with everything and its mandrel bent but i heard that flowmasters dont sound too good on a v6 stang HELP!!!!!!!!!!

Danger Dude · 06-28-2005, 03:20 PM


Quote: Originally Posted by mrd11387 oooooookkkkkkkkkk i dont know what to do.....people told me to put dynomax mufflers on my car because it sounds good,but i would have to have a muffler shop run pipes...here is the problem, muffler shops bend them and the flow is restricted and it loses backpressure.....i was thinking about getting the flowmaster cat back system since it comes with everything and its mandrel bent but i heard that flowmasters dont sound too good on a v6 stang HELP!!!!!!!!!!

What are you talking about. In one sentence you said they restrict then you say it loses backpressure.

Fact 1 Whether they are mandrel bent or prefab pipe is not a really big issue. The whole Mandrel thing is blown way out of proportion. On a street car mostly stock you will not notice any difference between mandrel or prefab bent pipe. So dont worry about this.

Fact 2 If you get Dynomax super turbos you will outflow Flowmasters and have better sound and actually free up HP. But dont expect more than 1 or 2 HP. The whole backpressure thing is also blown out of proportion. On a stock motor with cats you are not going to loose torque going to a flow thru muffler. That is just a myth told over and over by people who should be horse whipped.

mrd11387 · 06-28-2005, 05:02 PM

so i should just get the dynomax mufflers and have a muffler shop throw them on and rig up an exhaust?

97Stallion · 06-28-2005, 05:06 PM


Quote: Originally Posted by Danger Dude Fact 2 If you get Dynomax super turbos you will outflow Flowmasters and have better sound and actually free up HP. But dont expect more than 1 or 2 HP. The whole backpressure thing is also blown out of proportion. On a stock motor with cats you are not going to loose torque going to a flow thru muffler. That is just a myth told over and over by people who should be horse whipped.

I would actually like to argue this some. When I had my car with just a CAI, UDP, and duals with glasspacks, I dyno'd my car at 133.1rwhp and 189.4 rwtq. Relik recently dyno'd his car with the same mods except for three difference, his 98 came with 150 compared to my 145, he has a spacer and his duals used "Stock??" mufflers. His results were 136.4rwhp and 200.5rwtq. That's a 11rwtq betweent he two. I can post my dyno if you'd like. It is minimal, but i think the backpressure is still a tiny factor until you seriously mod your engine.

lowflyn · 06-28-2005, 05:18 PM

If I was you, I'd get the exhaust shop to fab it up. You'll prolly come out cheaper that way and it won't make a difference on a near stock car.

Danger Dude · 06-28-2005, 05:24 PM


Quote: Originally Posted by 97Stallion I would actually like to argue this some. When I had my car with just a CAI, UDP, and duals with glasspacks, I dyno'd my car at 133.1rwhp and 189.4 rwtq. Relik recently dyno'd his car with the same mods except for three difference, his 98 came with 150 compared to my 145, he has a spacer and his duals used "Stock??" mufflers. His results were 136.4rwhp and 200.5rwtq. That's a 11rwtq betweent he two. I can post my dyno if you'd like. It is minimal, but i think the backpressure is still a tiny factor until you seriously mod your engine.

Rob you are talking about 2 different cars and different ages and different mods and equipment. 3.3 HP can be from a semi-bad plug or even a difference in dynos. The fact is the Cats are a bigger restriction than mufflers. When I did my dyno before and after Dual exhaust I gained 1.5 hp and lost no torque and I have Ultra flows which are free flowing mufflers. Back pressure does not become a issue until you start building a engine for higher Hp in the where every little bit counts especially when you are drag racing on a track. The stock exhaust is not that restrictive on a stock motor. The whole Dual exhaust onb a stock motor is more for sound and looks not really a performance mod until engine work is done

**SpectorV** · 06-28-2005, 05:30 PM

you cant compare dynos for different cars or even two different dynos (actual different dynos) for that matter. Exhaust helps, but not by much, you need to look at the overall powerband improvment not just the overall peak.

97Stallion · 06-29-2005, 12:17 PM


Quote: Originally Posted by SpectorV you cant compare dynos for different cars or even two different dynos (actual different dynos) for that matter. Exhaust helps, but not by much, you need to look at the overall powerband improvment not just the overall peak.

Sure you can! So basically what you're saying is that two different cars with the same mods will never dyno the exact same. I agree with that, but I should still able to compare my car to somepne elses regardless of where they dyno'd their car. All dyno numbers are suppose to be SAE corrected.

Danger Dude · 01:54 PM


Quote: Originally Posted by 97Stallion Sure you can! So basically what you're saying is that two different cars with the same mods will never dyno the exact same. I agree with that, but I should still able to compare my car to somepne elses regardless of where they dyno'd their car. All dyno numbers are suppose to be SAE corrected.

Ok Rob you are a intelligent guy and my friend. I am not about get in a heated debate with you on this but lets realize what SAE corrected is. Correction Factors are used to compensate engine horsepower measurements for differences in operating conditions during engine testing. The typical correction factor (CF) is calculated based on the absolute barometric pressure, air temperature and water content of the air used for combustion by the engine under test. It attempts to predict the horsepower that would be developed if the engine were tested at sea level under standard pressure and temperature conditions. So knowing this if the dyno is reading low or higher the SAE correction will follow those numbers for the corrections.

Case in point Rick dynoed a couple of years ago here in greer and everyone there was coming up short in HP numbers. It was a brand new dynojet dyno at a tech school. Rick the following week went to a dyno in NC and gained 16 Hp and he did nothing to his car. So SAE corrected is just a way to compenstate for enviromental conditions not the state or condition of the dyno or the people running it. And 3 hp from 2 different cars on different dynos on opposite end of this country will be different. I have been to over 200 dynos and even if you have 2 exact cars on the exact same dyno with the exact same mods things will be different. Like I said I gained several HP on a dyno by just cleaning up a tiny speck of a burr on the last thread of a single sparkplug exposed to the combustion chamber and they were brand new Autolite spark plugs.

**SpectorV** · 06-29-2005, 03:15 PM

correction factors are only as good as the variables used to correct them. If the altering or converting to a standard was done 100% correctly then you could definatly do what you say. The ability for us to correctly change all specs to a standards is lacking, its close but not 100% accurate, and some are WAY off so unless you know the people who run the dyno and how they set it and the specs needed to set em correctly and ect ect ect its not possible to be super accurate, only close. With dyno numbers a small percentage off thats enough to not be comparable.