The Pittsburgh Thread

[tahseenmahmood]

I dont know about every one else.. but i want to be Tigga with orange camaro with black stripes all over.. LOL

Originally Posted by demonspeed

Let's move forward with one of these:

[tahseenmahmood]

yup gave a lil headace too ..lol and im good at maths in genral..
Woow i never knew their could be such detail into making things so perfect even if its just an exhaust.. good that i am not an aerodynamic engineer

Originally Posted by Witt

While the math is somewhat correct, something like that isn't very useful imo. While zero loss is fine, on an NA application I think we all agree that you want a system designed for best scavenging relative to the engine in question. A supercharged engine, specifically on a positive displacement setup, not much of that really matters because your blower dictates the amount of airflow in and out of the engine. Exhaust upgrades on a supercharged engine do very little relative to an NA setup contrary to what some people might think.

If you have the time, this link is a good read with a little math behind the action.

[Seer]

Originally Posted by Swacer

A lot of assumptions in there, but in general really good back of the napkin calc there.

Just wish the author would cite where he got the equations from.

fwiw, I only saw gains from switching from exhaust manifolds to 1 7/8" long tube headers and removing my cats and this was on a 700+rwhp PD supercharged engine. I picked up 42rwhp but this is not scientific as the before and after dynos were not done on the same day in similar conditions.

All of my tubing after the X pipe was 2.75" and the X pipe itself was 3". I added 3" over the axle pipes, and it did very little.

Needless to say, larger catbacks rarely do anything, even for a bolt on car. What it did do though (the headers/cat delete) was reduce my boost and raise overall efficiency.

[demonspeed]

I believe there must be some significance to head flow, no?

So, for perhaps the modular motors there not a significant benefit to increase exhaust diameter. However, it's proven on the LS engines that 1 7/8" primaries make more power all over as does the 3" piping.

[063KS]

Originally Posted by tahseenmahmood

LMAO.. i guess this is photo shoped..

Ballin'

[Seer]

Originally Posted by demonspeed

I believe there must be some significance to head flow, no?

So, for perhaps the modular motors there not a significant benefit to increase exhaust diameter. However, it's proven on the LS engines that 1 7/8" primaries make more power all over as does the 3" piping.

I'm pretty sure the mod motor/coyote heads outflow the oem LS1,2,3 etc etc heads by a decent margin. One of the reasons for making similar HP and Torque numbers at much lower displacement.

Like I said, I only saw gains by taking off the cats and switching to headers.

[demonspeed]

Originally Posted by Seer

I'm pretty sure the mod motor/coyote heads outflow the oem LS1,2,3 etc etc heads by a decent margin. One of the reasons for making similar HP and Torque numbers at much lower displacement.

You're [I believe] correct in regards to the Coyote; I'm not sure the 2v (including PI), 3v, and 96-04 4v out-flow the LS, though. I have no idea what your 5.4 stuff does, either.

[tahseenmahmood]

The bigger the better they said.. go crazzy they said.. LOL

[tahseenmahmood]

I do like the 3rd blue car.!!

[Swacer]

Originally Posted by Seer

fwiw, I only saw gains from switching from exhaust manifolds to 1 7/8" long tube headers and removing my cats and this was on a 700+rwhp PD supercharged engine. I picked up 42rwhp but this is not scientific as the before and after dynos were not done on the same day in similar conditions.

All of my tubing after the X pipe was 2.75" and the X pipe itself was 3". I added 3" over the axle pipes, and it did very little.

Needless to say, larger catbacks rarely do anything, even for a bolt on car. What it did do though (the headers/cat delete) was reduce my boost and raise overall efficiency.

Makes sense, the back pressure created at the reservoir of the maniford (diameter minimum 2x inlet pipe diameter) is quite large just do to the lack of space. You have severe choked flow going into the cats. I"m sure that done for emissions in order to minimize volumetric flow into the cats...but jeez.

As for the 42hp...do you think its a factor of the amount of power being made by the car? As in the amount of gain is proportional to the power being created? Because most of the N/A cars are only seeing 30hp.

Finally, the back half of the exhaust makes sense, .5" diameter gain over the distance of the exhaust will reduce the losses "slightly", but nothing really measurable. The biggest differnece would be the routing of the exhaust, which between sizes would be relatively the same.

[demonspeed]

Originally Posted by Swacer

As for the 42hp...do you think its a factor of the amount of power being made by the car? As in the amount of gain is proportional to the power being created?

Unequivocally, yes.

[Trav2SS]

Its true though if the exhaust tip is at least 3 inchs and angled upwards, or the entire muffler at a slant.. its at least 12hp and .5 off the quarter mile. And one doesnt even need the rest of the exhaust. Red Light Street Facts right there boys..

[Seer]

Originally Posted by demonspeed

You're [I believe] correct in regards to the Coyote; I'm not sure the 2v (including PI), 3v, and 96-04 4v out-flow the LS, though. I have no idea what your 5.4 stuff does, either.

GT500 and Ford GT Supercar share heads. From the research I am seeing at .500 the GT500 head flows about the same as the LS7. Only difference is, you see a lot of LS7 Z06's running aftermarket cams with over .600 lift, where anything really over .500 lift on a dohc 4v is useless and is never used for aftermarket cams, so its tough to do a apples to apples comparison.

But from what I am seeing at .500 with 28" of vacuum both heads are around 330cfm on the intake side.

[Seer]

Originally Posted by Swacer

Makes sense, the back pressure created at the reservoir of the maniford (diameter minimum 2x inlet pipe diameter) is quite large just do to the lack of space. You have severe choked flow going into the cats. I"m sure that done for emissions in order to minimize volumetric flow into the cats...but jeez.

As for the 42hp...do you think its a factor of the amount of power being made by the car? As in the amount of gain is proportional to the power being created? Because most of the N/A cars are only seeing 30hp.

Finally, the back half of the exhaust makes sense, .5" diameter gain over the distance of the exhaust will reduce the losses "slightly", but nothing really measurable. The biggest differnece would be the routing of the exhaust, which between sizes would be relatively the same.

my stock exhaust is 2.75", so the gain was .25"