When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Oh yeah, I would definitely not use the Mugen header on a supercharged car. Being designed for more midrange torque on an NA car would tell me that it won't flow enough for a supercharged car (at least to make a difference).
If you're willing to get loud, exhausts can make a difference. We did a before and after last weekend on a single exhaust. Same day, same car, picked up 5+ hp all throughout the VTEC range from 6k to the limiter. Even picked up some below that too.
my logic (flawed?) was that on the NA cars, mugen gained mid, lost a little high and spoon gained mostly toward high side.
with the SC, i have the high end covered, so maybe the mugen would help increase the midrange for me as well, and its highend loss would be offset by the SC gains.
we were surprised that the reverse seemed to be true, i.e. lower numbers in low and midrange and better at peak with the mugen installed.
we did not spend a lot of time on the tuning because it somehow decided to do some pinging around 8k, so he did richen things up a bit to play it safe for now. he said we could lean things a little on the low vtec settings which could have put in on par/better than stock numbers.
pete switched to a single last month, but it is his fun car. this is my only car, and for a daily driver, i do not think i could take it that loud. my supersprint exhaust gets a little louder around 4k or under load/acceleration, but at speed it does not seem to be much louder than stock, oval tips fit the back end real nice, and there is only a 4 hp loss from running with no exhaust so it does not seem it is overly restrictive.
i did not drop the stock exhaust to see what difference it has for comparison. no idea what the effect would be to swap the stock header back on and continue to use the SS exhaust for look/sound or go back to stock exhaust as well. last dyno with stock H/E was 5 hp less than with the mugen/SS combo, so on the surface, it does not look like much to be gained.
either way, it would be time to swap them out, then some more cash on the dyno, then time trying to sell them, etc.... since it is not worse, i may just keep them until some other FI guys do something that shows a definite gain, then copy them.
With a supercharger, the engine is essentially behaving like a bigger engine. The more boost, the bigger the engine. For a given header design (tube size, length, etc.), the more displacement you have, the lower the rpm you'll get the benefit. Above that point, the header may (will) become increasingly restrictive.
Thus, with the Mugen header, designed to benefit the car down low and being a little restrictive up top, you're just moving the point of transition down a bit.
There are many other factors involved that can cause things to happen quite differently, but that's the gist of it.
i can understand the moving down part, i.e. instead of losing power at 8500 on NA, the extra push from the blower causes it to lose power at 7500....
my point is i saw exact opposite, i.e. lower power in low/mid range and better power at peak.
from what i have read in the past, i would have thought that the spoon header would perform better at top end. using your statement, i would assume that the power from the spoon should start to assert itself lower in the rpm range for my SC than it would for a NA.
pete and i have been experimenting a little. i have a MY00 with a 4.375 pulley, he has a MY02 with a 4.25. he has a OBD-II data logger and we have seen that i have lower spark advance, but he has lower IAT, even with his higher boost level. neither of us have an aftercooler, but he did have a pipe run to the front of the radiator for intake, and i have the stock comptech box on mine.
i did runs with stock header/exhaust and 4.575 pulley, and 4.375 pulley with stock H/E, then with mugen header and supersprint exhaust. both 4.375 pulls were close, i.e. no large gains/loses seen between stock H/E and aftermarket H/E.
boost level for me maxed at 5.83 with the 4.575", 6.8 with the 4.375", pete got 7.2 with the 4.25".
i had a larger boost gain with stock H/E going .2 smaller (almost 1 lb) and pete went .125 smaller than me for a .4 lb boost gain, but he had a much larger HP gain. we know there are differences between the 00 and 02 ecu, just cannot document exactly what they are.
we were thinking it was the stock h/e, and i have been thinking about getting them for months anyway. maybe i ended up buying the wrong header.... have you seen better results with SC and another header brand?
1. Multivariate response - you changed more than 1 factor between tests. I have no doubt the Mugen exhaust flows better (more airflow) than stock. This is good for a blower motor. The Mugen header, IMO, is not suitable for a blower motor. Put both items on the same engine and what happens? You tell me since you tried it :-).
2. Test conditions. Were you monitoring coolant temps as well? How consistent were they?
Finally, how big of a variation did you see. Looks like only a couple hp until the very top of the power curve.
The larger hp gain with less additional boost could be due to increased restriction causing you to back up more exhaust into the cylinder (or evacuate less) and dilute the incoming charge. It can also cause detonation issues, as we know ;-).
1. did not put on a mugen exhaust.... i did try mugen header with/without supersprint exhaust, difference was only 4 hp. from what i have read, the exhaust will not GAIN hp, it is more along the lines of how much it loses, so i do not think a mugen exhaust could get more than that 4 hp back.
2. did not monitor coolant temps, or have the obd-ii setup the first time to check IAT and Spark Advance. the stock header run was also different than the mugen/supersprint combo with adding the hondata intake gasket, spoon radiator cap, mugen fan switch and mugen thermostat. these additions should help the heat buildup issue between dyno runs, but do not expect it to help in the power issue.
the variation was -5.6hp/-4.86tq @6000 and +8.52hp/+5.43tq @8300. i do not have repeated runs with both setups to average it out and realize that each run will be a little different just with margin of error, weather conditions, etc.
pete has dc header and spoon n1 exhaust (i believe... it is a single that he switched to recently). i have not seen any claims that the dc header gets any big gains, and the single exhausts have all gotten better results than duals so i would expect his to be a little better than mine here, but again only in the area of 4hp that i lost with/wo exhaust on the car.
it is times like this that make you wish you had all the parts laying in the shop and a dyno close by that you can mix and match to get the best combo. of course that kind of cash is hard to come by....
"it is times like this that make you wish you had all the parts laying in the shop and a dyno close by that you can mix and match to get the best combo. of course that kind of cash is hard to come by...."
Indeed, that's one of the reasons I bought my own - dyno that is :-)
Well, I think I will install the headers tomorrow, as the weather is goiung to be beautiful in Dallas. I currently have the car up on ramps and from inspecting under the hood and under the car, it doesn't look like a difficult job. Some prior posts have stated that the headers must be installed brom under the car. However, it looks to me that it would be an easier job through the hood. Do any of you have any experience you can share with me. I'd like some suggestions before I get started.
01-14-2003, 10:13 PM
