How would you tune EFI for straight pipes?

wescoas1 · 08-15-2004, 01:09 AM

I have been wondering about this: It has become apparent that straight pipes are the most efficient way to go concerning motorcycle exhaust tuning, given its prevelance in MotoGP on four-stroke machines. Now, how would one set out to optimize the EFI for their bike with MotoGP-style straight pipes? Would a PCIIIR with ignition advancing do it? Would it require custom engine work? Would it require a custom pipe designed to have a little back-pressure? How would one go about doing this to maximize power delivery???

wescoas1 · 09-01-2004, 11:14 PM

How about this: anyone know how the MotoGP guys did it?

alaska cajun · 09-02-2004, 12:20 AM

The PC111 would be a must,the stock ECU,as good as they are,just won't have enough range.

Back pressure is a whole nother can of worms.Take a look at Microns full Serpent system and all the R&D that goes into finding that sweet spot to knik the pipe to give it the max HP.

I'm running str8 pipes on my VTX and it has removable baffels.Sometimes I'll run without them and I can feel the power loss.Not that it's alot but enough that I know it.

On the track where 1000's of second count,it could matter.

wescoas1 · 09-02-2004, 01:03 AM

Interesting, why do you think MotoGP went to straight pipes then? To actually de-tune the bikes? I know it's possible, but I don't know if that was the reasoning...

alaska cajun · 09-02-2004, 01:16 AM

It's pretty much common knowalge in the v- twin world that str8 pipes give better HP gains.It's just that getting that perfect amount of back pressure is the trick and harder to do on a inline.

With the PC111 and a good Dyno tuner,I think you would be able to achieve the goals you seek.

alaska cajun · 09-02-2004, 01:27 AM

Take my VTX.

In stock form,95,96 HP and roughly 110ft/lbs of toruqe.I added a PC111,Vance&hines str8 pipes and a open air 3 1/4" K&N air filter.All of this with a custom map.

I'm now at 101HP and 121ft/lbs of tourqe.This bike weighs 750lbs and will now pull the front wheel in 3rd gear at 70 mph.

Scotteq · 09-02-2004, 06:24 AM

Quote:

Originally Posted by wescoas1

I have been wondering about this: It has become apparent that straight pipes are the most efficient way to go concerning motorcycle exhaust tuning, given its prevelance in MotoGP on four-stroke machines. Now, how would one set out to optimize the EFI for their bike with MotoGP-style straight pipes? Would a PCIIIR with ignition advancing do it? Would it require custom engine work? Would it require a custom pipe designed to have a little back-pressure? How would one go about doing this to maximize power delivery???

The Short ANswer - Buy a PCIII, install it, then take your bike to a good tuner, and have his tech do lots of dyno runs to optimize the fuelling.

IOW - No different than anything else.

Scott

evils-03-RR · 09-02-2004, 08:40 AM

My question is, you running track only on that bike, or running street too. Personally if your running street and you pulled up next to me on your bike with str8s on it. I might kick you over. The sound is annoyingly loud, and down right crappy sounding. But thats my opinion. But if it's for track then I understand. Like my buddies Katana750 Has a full race D&D system. I hate riding with him because of it.

RACER X · 09-02-2004, 08:49 AM

world of difference from moto gp to a streetbike........basically no comparison.

wescoas1 · 09-03-2004, 11:19 PM

I would not say that there is no comparison, although of course they differ in many significant ways. And yes, I ride straight pipes on the street sometimes. Some people hate it, some people love it. I love it. The sound at 12,000 RPMs with straight pipes is brilliant, as is the idle. No louder that a Harley with straights on either, so why split hairs?

hybrid · 09-07-2004, 02:53 PM

The first mistake is to think the pipes on moto gp are straight pipes. Straight pipes mean exaclty that straight to open air.... meaning no collector. On exhaust the collector is last factor in power delivery. I have never seen a bike make more than negligible power without the muffler. I dont build pipes so I couldnt get too techy on the subject so I wouldnt be a really great help in the math part. My suggestion? leave the muffler on as even if it was for track only, most tracks enforce a decible limit.

wescoas1 · 09-18-2004, 07:31 PM

I believe that they actually are straight pipes these days without collectors. M1, RC211V, Desmosedici, you name it.

MAGNUM636 · 09-20-2004, 05:03 PM

A straight-pipe is different from a straight-through muffler. The muffler, while flowing the same, would dampen the exhaust pulses decreasing noise and usually brings back some of the low end torque that would be lost with a straight-pipe.

hybrid · 09-20-2004, 07:56 PM

if it was straight pipes on moto gp then the honda would have five outlets, no? No for it to have two outlets it must run through a collector to chamber into one pipe. Hence they are not straight pipes. Anyways I didnt answer this thread for speculation on what a race bike has on it. I was stating that straight pipes are for a very very narrow power band such as a top fuel drag car. Even the damn F1 cars are run into collectors, it is the easiest way to fool mother nature into thinking it is a longer pipe than it is, and still have the short pipe for high rpm. That is why you now have tapered head pipes on some exhaust they also use crossover pipes. So enough with the speculation and get over it. It would be a bad idea to use straight pipes okay?

wescoas1 · 09-20-2004, 11:15 PM

By straight pipes I meant pipes with no muffler (aka, end can or slip-on), not without a collector, those are two different things. Perhaps my wording was off, but you know what I mean. So why is this such a bad idea? Sounds like it works for F1...