Header Question

[dlra600]

Just a quick rule question.
Is it ok to have the headers terminate under the body[as in ending at the collectors].?
All the cars I have pictures of all have pipes coming out from under the car,yet the rulebook does not specify this.
The rulebook is happy if the pipes do not point towards tyres,fuel tanks or track surface.
As the pipes are soon to be made a swift response would be appreciated. Thanks Ian

[momec3]

As the rule book says is how it is. Straight off the collectors is fine.

Chris

[dlra600]

Thanks

[momec3]

BTW welcome aboard,

What are you building or is it top secret. What class are you aiming at?
Any other questions yell out.

Chris

[Dr Goggles]

I think this will be Ian who has posted a similar question on Landracing.com
http://www.landracing.com/forum/index.p ... #msg157932


The only rule that you need to be careful of would be the bit about not pointing directly at the salt wouldn't it people?

[momec3]

My little spy heh Giggles, A/Gas coupe.
A simple question got a simple answer.
I last ran the headers out the sides in my XP Ute as did Haddie in the Commodore, Bob Ellis in his coupe and others.
I've since came to the conclusion that it was a mistake as it screwed up the airflow beside the body.
Big Gaz does it because of lack of options/space.
Ideally from my study with what we do, (and lacking Renaults wind tunnel) we should dump the exhaust into the void of turbualant air behind the vehicle to help balance this area some.
This creates a catch 22 for me as an engine man because a well tuned race engine has a very exact header length, and the style of cams we choose are often effected by any sort of exhaust.
So again as an engine man and remembering the car is merely a life support system for an engine the engine always wins with me. Correct length headers that exit under the car!
Form your own opinions. Results may vary.
Chris

[Stayt`ie]

a well tuned race engine has a very exact header length, and the style of cams we choose are often effected by any sort of exhaust.

Chris,,, another way to say it, would be,, cam timing has a direct relationship to exhaust design,,

[dlra600]

Ya gotta get up early to get one past the doctor.Yes,thats me asking the question on landracing.com.
The car is the ex Van Dyk/Lambert car 326.Now running a478 c.i. BBC.,N/A EFI with a Tex 101 box.
I first went to the Lake in 03 & thought if I had found Lake racing first I possibly would not have gone drag racing.
[However up until then drag racing was still as much fun as you could have while still wearing pants]. Anyway no drag racing in Adelaide & I think I bought the Trans Am in 06 or 07 & slowly piecing together a combo for A/GC.
Went back to the Lake in 06 & last year.

[momec3]

a well tuned race engine has a very exact header length, and the style of cams we choose are often effected by any sort of exhaust.

Chris,,, another way to say it, would be,, cam timing has a direct relationship to exhaust design,,

Very correct Stayt'ie.

With Supercar stuff we used to screw with position of the torque curb by adjusting ram tube and header length. This got to a point of 1mm length adjustments would make a measurable difference. The interesting thing was if you say removed 1mm from the ram tubes you could increase the result by adding an amount of length to the headers and visa versa. Primary, secondary and overall length of the headers was also screwed with to give various results. We had a variety of different ram tube shapes as well that gave different results. Different tapers as well as lengths. Tested a multitude of combinations and many sets were tested once and shelved if they did'nt work. Tuning for different climate and/or altitude was done with ram tube length. Bathurst was a compromise because of the altitude difference between the top and the bottom of the mountain.
This style of development is at the high end of the anal retentive scale. As you push your development to the end of horsepower per cubic inch scale the detail involved in producing more power increases expotentialy. The testing and prototyping above was thousands of hours of dyno time. The 4 years I spent in that game the end result perhaps a 5% increase in HP and torque. Once a naturally aspirated combination is at its peak theres no place left to go. Almost.

Sorry Ian, don't think this was the answer you were after but its been quiet on here lately.

Chris

[Cookey]

Just had the opportunity to look in on Haddie's rebuild of the Bronzed Aussie Commodore and he is running the NASCAR type of exhaust that runs massive pipes beneath the car and then they exit via vertical splitter ribs at the rear end of the car.
Apparently this system works very well in as much that the hot exhaust gasses have a positive effect on the entrapped air immediately behind the car

[Stayt`ie]

dlra600,,sorry to hijack ya thread here, only take a moment ,,,
Chris, interesting what you have to say in the post above,,, it would be great to have that amount of dyno time,, the modern "high revving" motorcycles of today arre still stuck with 70s exhaust theory/tuning/mindset,, the little time i have spent messing with header/megaphone (cam timing) on the dyno, has seen very good results ,, ram tubes, have done a heap of calculations, but still have to test them on the dyno

[boyracer]

Not to contradict Chris at all but bit of info' on bangshift website the other day. I imagine Chris has forgotten more about tuning than most will ever know. Interesting the hole in curve from open zoomie headers.... Would this affect Salt speed, assuming you could get on top of gearing and into peak power range?

ttp://www.bangshift.com/blog/BangShift- ... art-1.html

[momec3]

Could not open the link to yours boy racer.
There are always a variety of different ways that often end in similar results. My thoughts are limited to my experience and theres much to learn from others.

The R&D budget in Nascar makes anything we do here look like small change.

Chris

[Rob]

Try this one Chris,

http://tinyurl.com/3krjk98

Cheers,
Rob

[momec3]

Thanks Rob

Few things i noticed. There test engine is fairly lazy at 1.39 hp per cube at peak so its a nice street engine. As you start increasing this number the exhaust changes become more significant.
The headers are 4 into 1 and the primarys look fairly large. Far from an optimised exhaust.
Could possibly gain significant mid range torque with properly designed tri y pipes and
peak power would'nt alter much
Their testing was brief and vauge but at least they had a go and were not afraid.
Open headers on an atmo motor just kill torque.
My opinion only.

Chris