Header Performance?

[Nessism]

Found an interesting ad from Supertrapp in the March 1983 Cycle World magazine referencing a header comparison test performed by Joe Minton for Rider magazine.

Yes, biased ad - paid for my Supertrapp but interesting none the less.






Basically, adding a header will at BEST case add 2.1 hp

Only one header added power at 7500 rpm and most LOST power over stock.

Not sure what would happen with pods but I suspect the results would be similar.

Weight reduction with a header compared to stock is noticeable, but this test clearly shows that performance gains are marginal at best.

.

[Bert Patterson]

I don’t know that I would’ve bothered putting a header on my bike if it didn’t already have a header and K&Ns. When I bought it, it had a Kerker. I trashed that for a V&H just for the relative ease of oil changes (which are still an absolute b!tch, but I don’t have to remove the pipes). Stock pipes are mainly…….hard to find.

[focus frenzy]

things have not changed much, I have spent some time on the D&D website looking at dyno runs and at best, only a few hp are gained with one interesting exception.

Harley Davidson! there was a healthy improvement in power over the stock pipes.

[woodman]

On everything but the dressers harley pipes are both on the same side. This causes problems with the way the EPA takes its noise readings so the pipes are really retrictive. Pipes, 2 jets and a Screaming eagle air cleaner is an easy 10 + hp on them. On my GS1100 the weight savings has to be worth something over stock pipes plus they sound better with the V&H pipe that was on it when I bought it. Minton didnt put a lot of work in the tuneup dept if he got less power then stock. Like you said Supertrapp paid for it. They are good pipes, I have one on my Fatboy but they need extensive baffle mods to work. When I first put it on it ran worse then stock and thats bad !

[triffecpa]

Harley Davidson! there was a healthy improvement in power over the stock pipes.

My guess is that's part of Harley's philosophy of selling you a bike and then selling you a boat load of accessories and performance parts. They want to be able to show the customer (Harley shops are one of the most common places to find dynos) that their hard earned money bought them real power gains.

Harley has the engineering ability to produce stock pipes that make as much HP as the aftermarket ones, but why bother? they know that the majority of the buyers will opt for aftermarket pipes and since the dealer offers that part and installation services and it won't void your factory warrantee, it's a win-win for the customer. Until they realize of course that they over paid, but that's also part of the Harley mystique.

TR

[focus frenzy]

My guess is that's part of Harley's philosophy of selling you a bike and then selling you a boat load of accessories and performance parts. They want to be able to show the customer (Harley shops are one of the most common places to find dynos) that their hard earned money bought them real power gains.

Harley has the engineering ability to produce stock pipes that make as much HP as the aftermarket ones, but why bother? they know that the majority of the buyers will opt for aftermarket pipes and since the dealer offers that part and installation services and it won't void your factory warrantee, it's a win-win for the customer. Until they realize of course that they over paid, but that's also part of the Harley mystique.

TR

actualy it is just like woodman said. they have to get the bike to pass federal noise standards. problem is they cant put a large muffler on them as that would screw up the looks of them. just look at that yamaha road warior super cruiser thing. so they end up with a cool looking small cigar shaped muffler that doesn't flow squat.

the Japaneese are having to use electronic tricks to get by the standards. my SV1000 keeps the electronic secondary throttles closed down till 4th gear to keep the sound level down low enough to pass the drive by test.
and the SV has two huge heavy mufflers. Harley has done a great job of getting the noise down without having to resort to huge cans.
unfortunatly that is the first thing Harley owners throw away.

[Billy Ricks]

All they did was remove the airbox lid and up the mains a bit. The Supertrapp has the advantage of adding or removing discs for tuning purposes. This test was biased and wasn't done correctly. A proper jet kit and either pods or a K&N replacement filter would have made a difference with the rest of the aftermarket pipes. One quick way to screw up tuning and lose power is to remove the airbox lid and do little or nothing with the jetting. Throw a free flowing pipe into the mix and jetting is way off.

[Dan Ruddock]

All of this is why I looked long and hard for a bike that still had the stock exhaust and I am very glad I did. A good 4-2-1 which most of the new bikes have gone to is far superior to a 4-1. The added plus is I like quiet bikes and my neighbors thank me for it. I am sick of hearing loud Harley's Dan

[Nessism]

Supertrapp didn’t pay for Minton’s test, they just published the results in their ad.

Regarding headers making more power than stock, it’s clear that in many cases they don’t. I don’t think this has anything to do with “tuning” the mixture or what have you, but rather many of the headers are simply bent tubing and are not optimized for the engine the way the stock Suzuki exhaust systems are.

I’ve seen lots of these tests over the years and the only way to get more power out of the bikes usually involves adding a lot of noise. I’d love to find the original Minton test so see how loud that Supertrapp was. My guess is that they had a lot of discs stacked on the silencer and the system was quite loud.

I’m not totally disrespecting headers since they do drop a lot of weight off the bike. I just don’t think they add much power to an otherwise stock bike contrary to popular belief.

[Mark M]

I’m not totally disrespecting headers since they do drop a lot of weight off the bike. I just don’t think they add much power to an otherwise stock bike contrary to popular belief.

Just swapping out an exhaust system is not going to be a huge change, unless the previous one was terrible. I do think that our bikes are very corked up to get them past the noise and emission requirements of the day.

Anyone who has added a pipe AND pods and jetted it properly will tell you it makes a very significant difference to performance and the character of the bike. Much greater than just a pipe alone. What the dyno numbers will not tell you is how throttle response, how fast the engine revs and how it picks up through the gears are changed.

My 1100E was dyno'd with a Kerker 4-1 and a modified airbox that had the rear half replaced with a big K&N filter (by the PO, before I bought it). It made 102rwhp/68.9ft-lb at over 3500ft elevation. Comparing to the ad numbers, I got 96rwhp @ 7500rpm and 98rwhp @ 9500rpm. Noticeably stronger than the ad above, with the inferior Kerker system. I was about equal to the stock system at 7500rpm and way above it at 9500rpm. Without altitude correction. Since adding pods, jetting it and degreeing the cams, it is noticeably stronger than when I bought it.

In the GS era, noise and power went hand in hand, but not so anymore. Look at the current 1000cc sport bikes, 150+rwhp and as quiet as your neighbour's Taurus. Unfortunately, to do this requires big muffler volumes, which look terrible on our classic bikes.

Mark

[salty_monk]

I can certainly feel the difference between the old setup & the new setup (pods & pipe) but you definitely pay for it at the pump a little & with day to day riding (at least in LA in traffic) it doesn't make any difference what so ever.

I actually prefer the 2 pipe look on our bikes.

Couple of things I've noticed:

1. Noise goes up - induction & exhaust. Despite what some say, I like the added noise & it does help in traffic (but only when lane splitting at low speed on the freeway mostly). I directly saw the results of people hearing me coming. (My pipes aren't "harley" loud - V&H on one, Yosh on the other).

2. Power band changes a little & throttle response improves (Power seems to move higher up the rev range but not much - probably more the pods than the pipe)

3. MPG decrease 2 - 8 mpg approx depending on how you're riding.

4. The 4:1 decreases standover height - actually it gives you a more direct path to the ground each side rather than going "around" the stock pipes effectively meaning shorter legs reach the ground easier.

5. Weight - Decrease is approx 20lbs. (Not enough to do a lot especially as the weight was carried low down & is "suspended" weight.

[Billy Ricks]

I could dig out some old Kerker ads that show graphs depicting something like a 10-15% increase in power when you do the jet kit, pods, and pipe.

[renobruce]

I could dig out some old Kerker ads that show graphs depicting something like a 10-15% increase in power when you do the jet kit, pods, and pipe.

Yes, I think just changing the pipe isn't going to do much in itself...you need to also rejet and throw some K&N's on.

The only comparison I can give is when me and Tom MLC did the dynodrags on our '78 GS1000's. His was all stock at the time, mine had a V&H, pods, and jet kit. With our reaction times being the same, I was beating him by a full second in the 1/4 mile.

[Nessism]

I could dig out some old Kerker ads that show graphs depicting something like a 10-15% increase in power when you do the jet kit, pods, and pipe.

The Supertrapp ad references an independent test by Joe Minton, not some dyno runs they staged themselves. To me this makes the information credible, which is why I posted it. Minton was a popular wrench guru back in the late 70's - '80's, and his real world hot rod articles were both credible and supported with factual evidence such as these dyno runs. I don't know why the bike didn't make more power other than to say that Suzuki did a pretty fine job of tuning the exhaust and intake to work together, and modifying the system only brings marginal improvements.

[Nessism]

Yes, I think just changing the pipe isn't going to do much in itself...you need to also rejet and throw some K&N's on.

The only comparison I can give is when me and Tom MLC did the dynodrags on our '78 GS1000's. His was all stock at the time, mine had a V&H, pods, and jet kit. With our reaction times being the same, I was beating him by a full second in the 1/4 mile.

There is another article in the same magazine with the Supertrapp ad where they took a Yamaha Seca 650 and bored it out, added cams, 28mm Keihin slide-throttle carbs, and various exhaust systems. The best exhaust system they tried, a Yoshimura, improved the 1/4 mile from 12.18@108.69 to 11.99@110.97. Not sure how much hp we are talking about to improve the speed by more than 3 mph but I suspect it's in the range of 5%.