BDR chassis dyno/side pipe test

[greg schroeder]

Originally Posted by native1

Finally back from the welder and then the dyno.. I must say I am little confused by the results. The pipes sound much better, a lot deeper but not much louder. Stainless specialities made the muffs and they were very nicely done. 3 inch straight through polished stainless 4 inch O.D. Heres were I get confused, my last dyno printout showed 467rwhp however the owner of the dyno said that convertd to 454rwhp. I don't know what the heck he is talking about but I guess that means it really made 454rwhp two weeks ago not 467. Maybe some of you guys can shed some light on these different software conversions???? Anyway, the new non converted HP is 461rwhp and 449rwtq. That means the new pipes made 7hp and 15fptq more. I was hoping for more considering this project cost 1000$ The carb fuel/air mix remained the same @ 12.9. The MPH @ 6200 was 130mph. I will post all different dyno printouts that I have, Maybe some of you guys can make sense of it all. So what's with the different conversions?? I was excited at 467 now I guess its really 461 but actually more HP. I don't get it?? I think the new headers will really help out. Will be a few months for those. Anyway the sound alone makes it all worth it but my goal of 500rwhp is going to hard to obtain without a little more help.

The numbers corrected when done on the same dyno would be most relevant. There are different correction factors. There are even 1/4 mile sea level correction calculators. The purpose is to put different condition testing of the same type into alike comparison. Cooler, drier air with more pressure makes the most power. Warmer, wetter air with lower pressure makes less power. Corrected numbers correct the values to a given standard, so you're comparing apples to apples.

As an example it wouldn't do much good to use uncorrected numbers and test a car on a 100F day with 60F dew point and 29.7 on the barometer then change the air cleaner and do the same test on a 27F day with 15F dew point and a 30.3 on the barometer then conclude the air cleaner produced 60 wheel HP. It happens, but it's just an invalid test.

A really good test for usable power in my opinion is 1/4 mile trap speed. I know guys with all sorts of hot street cars in the 300 to 1500 wheel HP range and trap speeds are really close to Dynojets. From there it's possible to correct to sea level with this calculator. I really like this method of 1/4 mile trap speed because it's reality.

http://www.modulardepot.com/density.php

Whatever test that's uses it's important to keep it consistent and look at change rather than the numbers.

This link is pretty good.

http://wahiduddin.net/calc/cf.htm

Your headers probably cover your exhaust ports right now. Those that came with my Superformance covered about 1/3 inch of width on each exhaust port. The new headers only added a bit, but seemed to give the top end a little push.