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Topic Review (Newest First)
01-01-2004 11:24 AM
rifraf Yes,I know,thats what sucked me into this site,kinda fun,aint it?
01-01-2004 11:17 AM
TurboS10 Gotcha, sometimes I can not tell. Alot of people on this site post stuff I find comical because to me it is just idiotic, but they are dead serious.

Chris
01-01-2004 10:49 AM
rifraf I think your missing my humor,its hard not to be a little sarcastic,and yes my 330 duration idea would fit the dual patern criteria, my point is there is no set standard for back pressure,just like different cam profiles work better with different flow needs,amount of exhaust needed to be expelled,port size, chamber shape,valve size,tube size and length and pipe and muffler configurations,all play a role,and yes,it is a fine line.No set standerd for just one of these.
01-01-2004 10:12 AM
TurboS10
Quote:
Originally posted by rifraf
If this is true,then someone needs to notify all camb grinders and have them make all low rpm cam exhaust lobes with lets say,330 duration and as much lift as the springs can stand, I think we might be on to something!
Ever heard of dual pattern cams? Duration can only be so much before overlap starts to be a problem. It is a fine line.
01-01-2004 09:39 AM
rifraf If this is true,then someone needs to notify all camb grinders and have them make all low rpm cam exhaust lobes with lets say,330 duration and as much lift as the springs can stand, I think we might be on to something!
12-31-2003 07:48 PM
L98vette1986
Quote:
Originally posted by Dubz
stepped headers work in this way to boost low end power and still maintain midrange and upper. Backpressure is important for torque production TurboS10, very important.
youre an idiot. Backpressure hurts torque/performance in every way. Tuning lenght of the exhaust system, and No backpressure increases the torque/hp.
12-16-2003 04:29 PM
bullheimer
read this

okay yeah this post is dead, but it's the dawn of the living dead remember?

i myself am not going to add anything other than to say i found some 60ft and 1/4 mile times done with 3 different exhausts with a 455 gto on this site http://www.pontiacstreetperformance....p/exhaust.html
there are three pages of stuff that prolly only the guys who posted in this thread will be interested in. i'll give you a summary: test one: open headers; test two: 3" exhaust; test three: 3"exhaust to the muffs and 2.25 out the back. i think you will all like this but.... and this is a big butt, it involves @ a 500HP engine. so it's not really for low output or stock engines.
12-14-2003 07:41 PM
DesmoDog
Quote:
Originally posted by Jag Daddy Wow that would equal 100% Bummer that would mean no exahust.
No it wouldn't... it would mean the exhaust has a certain restriction level, and the sum of the parts equals the total, hence the comment "15% of the total restriction..." etc. While this isn't absolutely correct, it's close enough for this forum and certainly nowhere near totally blocked.
12-14-2003 12:57 PM
Jag Daddy
Quote:
If I remember right, using a certain 5.4L V8 SUV as an example, the pipes make up about 15% of the total restriction. The cats are around 45%, the muffler about 40%? That's from memory, so don't quote me on it..
Wow that would equal 100% Bummer that would mean no exahust.

Regards
Mark
12-14-2003 12:10 PM
Richard B. Puryear
Re: small exhaust diameter up front and big out back??

Quote:
Originally posted by smlblcks10
i was just thinking about something and let me know if im right or wrong. the general consencus seems to be that smaller exhaust pipe diameter gives better low end torque and big pipes give better high end and revving capability due to the increased flow. now why not build an exhaust system that has both? it seems that smaller tubes closer towards the motor such as the headers and first bit of pipe coming off of them is the most crutial to low end torque (smaller tube headers=more torque, etc.) i mean look at high performance motorcycles and such. they usually have a very skinny header pipe which tapers out into a large diameter muffler. so would it make sense to build an exhaust system that starts out out with say 2" or 2 1/4" piping from the headers to the mufflers then uses 2 1/2" or 3" piping for the tailpipes?? wouldnt this give you the benefit of having smaller pipes close to the motor for low end and torque and then have the bigger pipes towards the back for less high-end restriction, plus the added bonus of having a deeper sound due to the bigger tailpipes?? or am i just talking out my a** and what you would actually have is a system with flow characteristics somewhere inbetween the two??
12-13-2003 06:18 PM
DesmoDog
Quote:
Originally posted by TurboS10
You have to realize that WE are overwhelmingly a minority. Most people are not hotrodders. Most people are like my wife that can understand why my 2000 chevy is so "damned loud". 3 inch mandrel pipe with dynomax muffler to get 10 HP is a waste to her, but to me it is money well spent. Plus, I like the sound. Much better than what chevy came up with
Chris
Ding ding ding! And we have a winner! For the most part Chris is right on the money. And he points out something else too - a 10hp gain from switching the exhaust. That's probably what, about a 4% improvement? So.. there isn't really that much to be gained by pouring a bunch of money and time trying to optimize the exhaust. The powerloss on a recent Lincoln LS was about 3%. That means the difference between a production system and a "loss free" system they use as a baseline was only 3%... It's just not worth it to spend the money to gain that, especially if you're giving up the desired sound quality to do it. (BTW, "perfectly quiet" is never the goal, but that's a whole different post).

It's really not as bad as some are making it sound here. It's not like there's 100hp lurking in the tailpipe that the OEMs are ignoring. People are at WOT, max power so rarely it's not a huge priority on most vehicles.

Bottom line: if you want to make power, spend your time and money on the intake/heads. There is much more power to be made there than in the exhaust.

Quote:
Originally posted by NAIRB
I worked at the Columbus, Indiana (Gladstone) plant.... snip... I didn't really know anyone in there and I can say it was truly a depressing place to work.
I was only at the Gladstone plant (aka "Happy Rock") once or twice. But in general, I find exhaust plants rather depressing too. Tech centers are MUCH more fun!

Quote:
Originally posted by Jag Daddy
Do bends in the exhaust system equal restriction?
Yes, bends do add restriction. The greater the bend, the more restriction. However... compared to the cats and the muffler, the pipes aren't the heavy hitters. If I remember right, using a certain 5.4L V8 SUV as an example, the pipes make up about 15% of the total restriction. The cats are around 45%, the muffler about 40%? That's from memory, so don't quote me on it...
12-13-2003 01:37 PM
ztoy Last yr I picked up an 'X' pipe exhaust from Dr. Gas and am quite pleased with it. Quieter but more power and better sound.

They recommended 3" from the headers back to the 'X', then 2 1/2" from there back to the mufflers. Can't remember all the technical reasons, but I am running a sbc pushing over 500 hp, and they said this would work best, and I think they were right. It pulls much harder than ever, sounds great, and best of all is quiet enough to hear someone talking. It was so loud before I couldn't even hear the radio playing, just a buzz. Anyway, it has something to do with the gases, the heat, and pressure, and at the back of the exhaust, 3" is a waste of money.

just my $.02 worth...
12-13-2003 11:00 AM
Jag Daddy This may sound like a stupid question, if it is then please excuse my brain fade.

Do bends in the exhaust system equal restriction?
If you have a system with many complex bends would it be more restrictive than say the same length of pipe that is fairly straight

Regards
Mark
12-13-2003 10:55 AM
Dubz
Quote:
Originally posted by TurboS10
Manufacturors are looking to please the masses......
and the aftermarket is looking to please us....and they do thier homework.

I'm almost glad that cars come stock with alot of junk performance hindering parts. If you had to spend $500 for a new exhaust to replace the stock junk, that gives you 10 hp it is easier to explain to the wife than a $500 exhaust that gives you 5 hp
12-13-2003 09:12 AM
TurboS10
Quote:
Originally posted by 4 Jaw Chuck
Thanks for the insight Desmo, sounds like a truly sorry state the industry is in when only the engine designers are allowed to run dyno tests. I guess it keeps the aftermarket companies in business?

You have to realize that WE are overwhelmingly a minority. Most people are not hotrodders. Most people are like my wife that can understand why my 2000 chevy is so "damned loud". 3 inch mandrel pipe with dynomax muffler to get 10 HP is a waste to her, but to me it is money well spent. Plus, I like the sound. Much better than what chevy came up with

Point is most people want a vehicle to run perfectly quiet and the exhaust rumble would be enough to make most not want my truck. Of course anyone on this board would dig it. Manufacturors are looking to please the masses......

Chris
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