Calculating FI Exhaust Header Size

[Bahndvr]

I have been looking into headers for a while and everyone one says 1⅞ is fine. I'm not N/A. I don't want fine. I've tried online calculators but I get some crazy numbers. Now I have stumbled upon a website that integrates superchargers, turbo and nitrous but I've done the calculation and get a number (inside header tube diameter) that can't be right. Can someone give it a go?
Here's the website:
http://www.ehow.com/info-tip_8428151_exhaust-header-length-calculation.html

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[BMR Tech]

What style of poweradder do you have?

I can tell you, I did not pick up much gain at the track going from stock headers to 1-3/4" LT headers on my VMP TVS combo.

 

[Bahndvr]

Roush Phase 2

 

[ProChargerTECH]

What style of poweradder do you have?

I can tell you, I did not pick up much gain at the track going from stock headers to 1-3/4" LT headers on my VMP TVS combo.

You wouldn't be the only one.

In fact I have seen some losses across the board on other modern platforms.

These OEM's really have their exhaust games on point these days.



(I have seen 1,400rwhp be made through stock Corvette mufflers, just to prove a point)

 

[Jay-rod427]

Ford did a lot of research and building of the try Y design of the stock headers. The only flow problem with them is the cats. Some will make claims of LT's adding more hp than cat deletes, but...

 

[BMR Tech]

I can only speak from personal experiences.

On my '04 Cobra, I gained big power with LT, and also gained 2.5 MPH

On my S550, I went [email protected] with stock headers and a 66mm Upper Pulley.

I added LT, and went down to a 63mm Upper Pulley on the SC and went 8.99@154

DA was within 100 feet. My car is very consistent, so those were pretty solid comparisons IMO.

 

[RockStang]

They may not make more power but they sure do change the sound. I love the way the car screams at WOT vs stock headers. Didn't like the valve train noise at first but don't notice it as much anymore.

 

[Bahndvr]

David Vizard said to use 2 inch primary tubing and 3 inch plus exhaust piping.

 

[Crackerjack17]

What style of poweradder do you have?

I can tell you, I did not pick up much gain at the track going from stock headers to 1-3/4" LT headers on my VMP TVS combo.

Did you have cats in the long tubes?

 

[toplesstripcruiser]

Alright I just went through a thread with shorties vs. longtubes. The consensus was there's power to gain from long tubes, which is why it's a common mod and is dyno proven. Now you guys says it isn't? Which one is it? Are longtubes good or not?

 

[Phoenix]

I can only speak from personal experiences.

On my '04 Cobra, I gained big power with LT, and also gained 2.5 MPH

On my S550, I went [email protected] with stock headers and a 66mm Upper Pulley.

I added LT, and went down to a 63mm Upper Pulley on the SC and went 8.99@154

DA was within 100 feet. My car is very consistent, so those were pretty solid comparisons IMO.

did you keep the stock cats on the stock headers? if not, would a set of high flow cats be advisable? im still on stock cats. looking at E85 in the spring.

 

[Terminator2]

Ford did a lot of research and building of the try Y design of the stock headers. The only flow problem with them is the cats. Some will make claims of LT's adding more hp than cat deletes, but...

I've had both and yes there is a gain with long tubes over just cat deletes.

 

[BMR Tech]

Stock Headers
MAK Cat Delete
Magnaflow Comp Catback
9.0@153

Borla 1-3/4" LT
Pypes 3" Turndowns
(so I also saved weight..lol)
8.99@154 - with a smaller blower pulley too

 

[Jay-rod427]

So essentially no change Kelly. Maybe even lost power with the added power of pulley.

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