Repsol Honda MotoGP Exhaust at Brno
Though I have photographed the Repsol Honda exhausts from many angles before, this morning I got a new perspective that shows just how different the ‘same’ exhaust systems can be from one rider’s bike to another’s. Design and length of the exhaust system are two elements that affect an engine’s characteristics. Please click on the above image to view it larger.
The media center here at Brno offers an overhead view of the pit lane. Looking down on Dani Pedrosa’s bike (shown left) and Marc Marquez’ bike (shown right), we can see that the shapes of the two versions of the Repsol Honda exhaust are quite different.
My perspective is not identical as the mechanics had moved Pedrosa’s bike farther away from the garage. You can see from the position of the rear tire that I’m looking at Pedrosa’s bike from more of an angle than Marquez’, on which I’m looking nearly straight down.
Comparison of the unprocessed photos suggests that Marquez’ seat is a bit farther back, which makes sense given that he’s taller. That there is more of the 2 into 1 section showing on Pedrosa’s bike may be accounted for by his seat being closer to the front of the bike.
The position of the seat also likely affects the position of the rear pipe hanger, which is visible on each bike and supports the pipe from above by attaching just behind the rider’s number.
You can also see the tip of the longer front-cylinder exhaust that Marquez is still using in the bottom left portion of the right side photo. Pedrosa is still using the shorter version, and that front exhaust is not visible on his bike from this perspective. This is curious because it appears from looking at these overhead views that Pedrosa’s bike has a longer exhaust path than Marquez’. The bend in this tail section seems designed to allow that straight section on the right side of Pedrosa’s bike’s pipe to exist.
Both of Pedrosa’s bikes have the design shown here, and both of Marquez’ bikes match as well.
By comparison, the Aspar Hondas of both Laverty and Hayden have identical exhaust sections that are quite different from those used on the Repsol Honda team:
UPDATE (2015-08-19): On Monday at the test, there was lots of down time related to the lousy weather. I took the opportunity to approach one of the HRC guys to ask about the differences between the Marquez and Pedrosa versions of this tail pipe section. I explained how I had viewed each from above and noted the different shapes/lengths of the pieces.
“You are very observant,” he commented with a wry smile.
I asked about why the riders had different pieces of exhaust pipe in this area and he confirmed that this is one of the ways Honda can affect the characteristics of the engine. Many things they can do with software, but physical changes such as different pipe length and design are another.
So it’s down to rider preference, I asked, Dani prefers one and Marc prefers the other? That was so.
I then rolled the dice and asked how changing the length of pipe affected what the rider felt from the engine. The smile grew, as did the degree of wry amusement, and when a slight shake of the head was added to that smile I knew I’d have to keep on wondering about this detail for myself.
But I appreciate very much the confirmation that the differences between these two versions of rear exhaust are determined by what each rider prefers when he twists the throttle.
Photographs: ©2015 by Scott Jones / PHOTO.GP – All Rights Reserved
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