KustmAce has 7600+ posts, which works out to five (5) posts per day, and is a moderator of this website. One would think that he would have the courage or decency to defend his own posts, even if he just cut and pasted something from someone else, he would have to have cut and pasted something he believed, especially given that he also made it a "sticky" post to sit at the top of the forum forever.
I am going to suggest that the inaccurate information in at least one key part of the post by KustmAce, deems that portion of the information totally worthless, and the remainder deserving of extreme suspicion, if it is just as inaccurate as the information that can be proven wrong.
Quote:
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Originally Posted by KustmAce
There isn’t a BEST exhaust pipe size per car, bills dynos show one thing, others have shown differently and a reputable company such as magnaflow makes theirs in 2.25, not 2.5, turbo benefit from different sizes and people with nitrous will do better with another.
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I will ask yet again, where are all these dyno tests.
For the last decade, I have been listening to people boldly claim they have seen or know of dyno tests to prove that smaller pipe makes more power, or that engines need backpressure to make more power. To date, I have seen none.
KustmAce claims that there are tests specifically showing smaller pipe works better for Chevy engines, specifically that other companies making exhaust systems for Cavalier have done and have published dyno tests to show this.
Where are they?
I went down the list of links KustmAce provided, here's what I found:
http://www.magnaflow.com - Tested their exhaust system only on Ecotec engine (
http://www.magnaflow.com/02product/dynos/15761.jpg , This test shows the same results as the Bill's test of Magnaflow PN 15761 on the Quad Four engine in their comparison test.). Can provide no comparison or development documentation showing any testing on any pipe size other than the pipe size of their product, can show no evidence that they even tested 2 1/2 inch pipe on this engine.
HAS NO DYNO TEST FOR 2.2 OHV ENGINE AT ALL.
http://www.thermalrd.com/about.htm - Declined to provide a dyno test when asked.
http://www.borla.com - Declined to provide a dyno test when asked.
http://www.rsmracing.com - This domain name for sale.
http://www.mantapart.com - Declined to provide any dyno test when asked.
http://carcustoms.net/store/ - No website at all, 404 error.
http://highrevmotorsports.com/catalog/default.php - This domain name for sale.
http://www.howellautomotive.com - Sells the Magnafolw product only, has no testing to show.
http://www.cavalierconnection.com - This domain name for sale.
Further research netted similar results:
http://www.obxracingsports.com/ - Advertises that their product is "Dyno Proven", but declines to provide the dyno test results when asked.
Oddly enough, the only place publishing any dyno comparison testing is:
http://www.iperformance.com at
http://www.iperformance.biz/dyno/exhaust01.html
This is a comparison of the Magnaflow PN 15761 against the Iperformance PN SHBILL14B. Both are mandrel bent. Both use Magnaflow mufflers that are straight through and the same size. The difference is that the 15761 is 2 1/4 inch pipe and the SHBILL14B is 2 1/2 inch pipe. The 15761 tests show nearly identical to Magnaflow's own test, possibly the Magnaflow dyno is slightly more generous. The
SHBILL14B shows 2.6 HP over the 15761, and the only difference between the two is the diameter of the pipe.
When tested, bigger is better, and for Cavalier, 2 1/2 is right.
For exhaust system information to paste, it might be enlightening to see how the rest of the world is laughing at us because so many cavalier owners in our midst don't have any concept of exhaust system design:
http://www.isuzuperformance.com/isup...h/exhaust.html
For non-turbo engines under 2.4 liter in displacement and turbocharged engines under 2.2 liter displacement and producing less than 400 HP, 2 1/2 inch mandrel bent exhaust pipe size is optimum for high performance. 2 1/4 inch pipe can limit air flow once the engine buildup gets serious and the owner has bolted on more than header, intake, and pulley.
Many people will claim that 2 1/2 looses torque, but this is not true.
As discussed earlier, all of the tuning for torque is done between the head and the final collector, in the header. After the final collector, the only thing determined by pipe diameter is how much work the engine has to do to push the exhaust gas to the back end of the car and out the tail pipe, and the less work the engine has to do, the more power it can produce.
The people advocating 2 1/4 inch diameter exhaust systems and complaining about low end power loss are also using 4-1 headers. This isn't unique to Storms, it is a serious misconception among the Cavalier/Sunfire crowd as well. These people are compensating for poor header design by strangling down the exhaust pipe diameter at the expense of mid and upper RPM engine performance.
All of this has been specific to mandrel bent pipe. Squeeze bent pipe looses 1/3 of its interior cross sectional area in a right angle bend. There are three right angle bends in the exhaust system of both the Storm and the I-Mark.
Mandrel pipe bending keeps a consistent inside diameter of the pipe through right angle and even U bends.
2 1/2 inch diameter squeeze bent pipe will flow the equivalent of 1.6 inch diameter pipe at each of those squeeze bends. The entire exhaust system will flow only as much as the tightest constriction in flow, meaning that all of the 2 1/2 inch pipe has been a waste, the total system will flow the same as a 1.6 inch diameter mandrel bent exhaust system.
To build a 2 1/2 inch diameter system using squeeze bent pipe, every bend would have to be made using 3 1/2 inch diameter pipe to compensate for the inside space lost from the squeeze bend. This means that the straight sections of pipe would be 2 1/2 inch pipe, then expanded to 3 1/2 inch bends for each and every curve, and then turned back down to 2 1/2 inch pipe for the straight pipe until the next bend.
The evidence stacks up rather high against KustmAce and his source for the post he pasted here and made sticky. Hopefully, other forum users will scroll down past his post to see the evidence that proves his statements wrong.