Ahhh, thanks Mac. Loss of velocity in an exhaust system is the same problem one finds when mouthbreathing shade tree wrenches grind the hell out of intake ports on a manifold/head without considering velocity of air/fuel mixture.

In this case, bigger isn't necessarily better...

 

that's very simple....you lost velocity when you uncorked the system......the idea is to make exhaust come out as easily as possible without losing too much speed....easiest thing i can think of is this...back pressure = wasted energy...if pressure is being created it is because exhaust gas is being created faster than the system can move it out, this in now way creates torque...you get a loss of torque if exhaust gas loses speed...imagine inflating a balloon..if the air pump is working at the same constant rpm..if the valve is very tiny pressure builds behind it without inflating the balloon any faster....if it is really big it inflates the balloon slowly...but if its just right the balloon blows up really quick...get it??

 

no cats-oklahoma

 

Gino, I saw that essentialSPEED shorty header, I am VERY interested in hearing how that works out. Thanks for your help, man.

 

No problem bro. I bought the EssentialSPEED header, knowing it was priced higher than most because 1) it has been designed to work flawlessly with both cats, 2) it's guaranteed to fit perfectly without mods or hacking, 3) it was designed specifically for mid-range grunt without sacrificing top end, 4) I've talked numerous times with Kevin Liphard--owner of EssentialSPEED about the header, its design, exhaust philosophy, etc., as well as other EssentialSPEED Pro parts, 5) EssentialSPEED is Protege friendly--they develop pieces for the car, including turbo kits and provide on-site installation of their Pro gear and 6) no off-the-wall claims are made for their mods that can't be proven with dyno data.

After I install the header, I'm sending the dyno chart to Kevin for comparison and his use. After that, I'll install the over-bored EssentialSPEED throttle body and pull some numbers. Cams follow. If I wanted to pull the engine, I'd also drop in a much-lightened flywheel and better clutch, but that's $$$ I'm currently not budgeting for mods.

I want to see just how many ponies and how much twist I can generate with an NA FE engine without higher squeeze pistons, bigger valves, port work, etc. Been there and done that with my Alfa.

 

The gains on the throttle body will not be much at all..couple of people upgraded to Corksport larger throttle body and saw little to no improvement!

You are better off getting yourself..some intake & exhuast cams!

Chas

 

only way you see a substatial gain from a bigger bore on the TB is in a forced induction application..although even then there are lots of mods more effective and less costly...leave it as a last resort on a turbo car....on an NA its a big waste of cash...

 

i would definitely be interested to see what the header dyno's like though. that's something that's bolt on without too much problem, and if it helps out enough, would be worth the money. keep us updated. later

 

Quote: originally posted by acidbbg1:
"I had a silencer in..and the car pulled nicely when leaving the line..
But when i removed the silencer..the car had to be rev harder..and didn't pull as quickly off the line!
So please explain!
B/c i happen to believe that back pressure was helping me off the line due to the silencer!"

i am starting believe that backpressure is not necessary at all, and that your problem with the the silencer can be explained here:

http://www.accesscom.com/~knliao/exh_theory.html

it discusses many things but it does mention how the stock ecu is tuned for certain exhaust flow characteristics and that it is not the engine that needs backpressure, but the ecu that needs it to manage it and if it doesn't see any backpressure, you lose power.
Hope this helps explain.

 

Everyone here considering any exhaust/header mods should read the piece you reference.
It's important to understand intake/exhaust relationships and their place in tuning.

Excellent read! Thanks for posting.

 

I'm using the entire Wagner exhaust, header, DP, MP....no cats on the entire car. It's a very quality piece made by an enthusiast. I recommend looking into it or pmming me for more info.

p.s. backpressure isn't helpfull, exhaust gas velocity is important...

 

Interesting read!