[QUOTE]Originally posted by shingles
[B]I agree with you on that different headers will make power differently.

 

Unfortunately, the days of being able to look at a header and predict its effects just by visual cues are long gone. There are some general rules of thumb, but you can only use them to comapre very similar designs.

A few things to consider:

1. Notice all the bends in the Mugen piece, particularly on the #2 and #3 cylinders. Besides making the unit an absolute bitch to install, they serve to make all 4 primary pipes of nearly equal length (I made a rough outside measurement on my Mugen). The stock unit is not equal length, nor are the Spoon or MG (#1/#4 are the same length and #2/#3 are the same length, but the #1/#4 combo is longer). The difference may not be much, perhaps only an inch. But that's enough to make a difference. For the Mugen, the equal length tubes would tend to mean that the header would be a bit peakier. All the cylinders have the same resonant frequency. For the other two, peak torque might not be quite as high, but the curve might be broader. Of course, this is comparing only one component of an entire engine system, so take it with a grain of salt.

2. On the topic of primaries vs. secondaries, you can probably expect the MG piece to make the most top end power. Why? Because while the primaries on all 3 models are of similar length (and probably diameter), the MG has the longest secondaries. Don't ask me to explain why I think that's the case. I tried creating a diagram to show exhaust pulse movement, but I couldn't do it. Conversely, the Spoon should function better on the low end with the Mugen in between.

In terms of 4-1 headers in general, you might look to the motorcycle industry and note what they are using. Many of the super high output 600s, including the R6 use 4-2-1 pieces, so 4-2-1 can make plenty of high end just like 4-1 can make low end too. However, a proper 4-1, perhaps with a race exhaust and no cat, should make more top end.

I believe John Grudynski at hi-Tech exhaust in Orange County tried a couple custom designs on the Reverend's car with poor results. Don't know if he tried a 4-1. John is pretty skilled and does race headers for alot of the top NA Honda drag racers as well as for a number of Formula Atlantic teams (high revving 1.6 liter I4 engines) so he knows his stuff. I've seen his headers pick up significant hp over any production stuff on the market for Hondas. In talking with him, he felt the ECU was holding them back, richengin up the mixture and cutting timing when airflow gains got too high. I don't know if he was using an OBDII scantool to check this, but I do know that since adding my Mugen I get more black soot on the tailpipes of my car. mdgrippa, you might want to call him and see what he has to say. Might save you some money.

I look forward to some more comparisons. I'm always willing to dyno my car as well Richard (just the Mugen header and JR filter - might be useful to see how much Prolene's TB adds since the exhaust doesn't do much of anything according to Vaportrail)

UL

 

UL! You are DA MAN!

Prolene and I are scheduling a few runs with Darren down in R&D (all my data's down there) on a Saturday, I would LOVE for you to come! Will you? Please let me know.

 

Sure Richard, you've got my email, right? Just drop me a line.

UL

 

[QUOTE]Originally posted by ultimate lurker
[B]Sure Richard, you've got my email, right?

 

Honda's CBR929RR, motorcycle sports switchable exhaust contraption that allows the exhaust to behave as 4-2-1 in lower rpm and 4-1 in high rpm. I think the review said that it was patented by Yamaha a long time ago. The patent finally expired.