Cormac Shoots Qatar: Exhaust Porn From The First MotoGP Race

By David Emmett | Mon, 07/03/2022 - 23:42


The upper exhaust on the KTM RC16, for the rear cylinder bank of the V4. No torque back pressure valve on it, unlike the Ducati and Aprilia.
The mesh on the end of the exhausts was introduced when the number of engines per season were limited after the 2008 financial crisis. The mesh prevents sizable stones from entering the engine and damaging it in the case of a crash.


Suzuki's Akrapovic-made 4-into-1-into-2 exhaust is exqusite in every way. Note the pipe joining the two exhausts just before the end. Stabilizes them. What's remarkable is that the exhaust is unchanged for this year, despite the engine producing a lot more power.


The Yamaha M1 uses another Akrapovic-made pipe (Akrapovic suppliers four of the six MotoGP factories). This particular pipe is so clean it is unused. You can see the weld on the interior part of the pipe, through the honeycomb mesh.


Both Aprilia pipes, newly fitted again, as you can see by how clean the inside of the lower pipe is. Like the Ducati and Honda, the exhaust pipes consist of two 2-into-1 pipes, one for each bank of cylinders of the V4. But upper and lower pipes are slash-cut to give them a larger surface area.
Aprilia switched from Akrapovic to SC Project this year, and the exhausts have undergone a slight redesign


Here's the upper exhaust, from the rear cylinder bank. Torque back pressure valve is on top, which opens and closes to produce more back pressure at low revs.
This exhaust is slash-cut now, unlike the early part of last year. This gives the exhaust a larger exit surface without increasing the diameter of the pipe.


The lower pipe. It is a slightly different shape, a little stubbier than last year's example. It may also be slightly larger, if the scratches on the surface are anything to go by. It is clearly touching down in corners.
The soot on the beehive mesh is another sign this pipe has been used in anger.

If you'd like to have very high-resolution (4K) versions of the fantastic photos which appear on the site, you can become a site supporter and take out a subscription. A subscription will also give you access to the many in-depth and exclusive articles we produce for MotoMatters.com site supporters. The more readers who join our growing band of site supporters, the better we can make MotoMatters.com, and the more readers will get out of the website. You can find out more about subscribing to MotoMatters.com here. You can also see these photos and all our subscriber material on our Patreon page.

If you would like to buy a copy of one of these photos, you can email Cormac Ryan Meenan

If you'd like to see more of Cormac's work, you can follow him on Twitter or Instagram, or check out his website, cormacgp.com.

PhotoPage
CormacGP
MotoGP
Losail, Qatar
Aprilia
KTM
Suzuki
Yamaha

Not sure I buy the "slash cut increases exit area" argument. To take advantage of that, the exhaust would have to turn a corner (to approach the grill at 90 degrees), hardly efficient. It would not surprise me to find that vectors are involved, and the dominant direction of the exhaust and its incident angle against the mesh determines effective "area". Additionally, if there is a performance effect, I wonder if it wouldn't be based more on the "impedence" of the end of the pipe. By this I mean, a sharp exit that is 90 degrees to flow would have a sharp, strong reflected pulse due to strong impedence mis-match (this could easily be undesirable). A slash cut has a "sloppy" reflection with the reflected pulse smeared out and weakened. 

By expanding from a ~60mm round pipe to a slash that is oval ~60x~90mm (or whatever) you are creating a low pressure area where the exhaust exits the pipe which in turn "pulls" the higher pressure gases behind it for a decrease in back pressure??? At any rate it would be certain not to create back pressure at the outlet. Mainly though, it just looks cool 

Agreed. The scratches are perpendicular to the direction of travel. Also, there are small scratches on the screen portion that could  never come in contact with the pavement unless through “ incidental “ contact.

Having replaced many many exhaust over my middling club racing “ career “ due to running out of grip because of ambition usually outweighing my talent made this an easy diagnosis. Good eye, though !

I saw pics of Ducati's long pipe during early testing but nobody seemed to know if it was possibly a distraction or something real.  It was on Bastianini's bike so it must be for real???  Any thoughts?

Given what Pecco has said about the 22 engine being abrupt or too harsh I think the long pipe was an attempt to calm the engine, bring the torque peak down, maybe at the expense of a bit of top end, which they can afford. I also think it didn't work. "Let Jorge and Johan figure it out", Gigi says, "Pecco you go back to 21 binky. Jack, are you still here?"

I'm gonna be a divider once again and say I LOVE the Gresini colors. Damn that looks good to me. Race bikes SHOULD be bold unconventional colors IMO. Kawasaki racing green with Muzzy, Lawson, Rainey et al, Yellow with speed blocks, Blue and White for Cooley. We gotta get back to bright colors. The times are too gray for black bikes, let's have some sunny, optimistic colors for a few years. Woohoo!

Even if you win the lottery, as far as I know they're all in museums now and not available. And there were only, what, five or six of them built? Despite my addiction to bikes and racing, that's the only bike photo on the wall in my study (rather grandiose name for a re-purposed bedroom).

This Britten device has consumed a portion of my brain since seeing it on the CYCLE WORLD cover in 1992. Pure passion and ridiculous engineering. If only there was a way for GP racing to go back to it's roots and wasn't such a business while still allowing David to report on it while earning a decent living. Heaven on Earth! I recently shed some tears of joy and nostalgia while watching a video of Michael Dunlop doing a commemorative lap of the Isle of Man TT circuit on a Gilera 500/4. 

To read the rest of this article, you need to sign up to become a MotoMatters.com site supporter by taking out a subscription. You can find out more about subscribing to MotoMatters.com here. If you are already a subscriber, log in to read the full text.

This is part of a regular series of unique insights into the world of motorcycle racing, exclusive for MotoMatters.com site supporters. The series includes interviews, background information, in-depth analysis, and opinion, and is available to everyone supporting the site by taking out a subscription.

If you would like to read more of our exclusive content you can join the growing band of site supporters, by taking out a subscription here. If you prefer, you can also support us on our Patreon page and get access to the same exclusive material there.

↑Back to top

Comments

Not sure I buy the "slash cut increases exit area" argument. To take advantage of that, the exhaust would have to turn a corner (to approach the grill at 90 degrees), hardly efficient. It would not surprise me to find that vectors are involved, and the dominant direction of the exhaust and its incident angle against the mesh determines effective "area". Additionally, if there is a performance effect, I wonder if it wouldn't be based more on the "impedence" of the end of the pipe. By this I mean, a sharp exit that is 90 degrees to flow would have a sharp, strong reflected pulse due to strong impedence mis-match (this could easily be undesirable). A slash cut has a "sloppy" reflection with the reflected pulse smeared out and weakened. 

By expanding from a ~60mm round pipe to a slash that is oval ~60x~90mm (or whatever) you are creating a low pressure area where the exhaust exits the pipe which in turn "pulls" the higher pressure gases behind it for a decrease in back pressure??? At any rate it would be certain not to create back pressure at the outlet. Mainly though, it just looks cool 

Agreed. The scratches are perpendicular to the direction of travel. Also, there are small scratches on the screen portion that could  never come in contact with the pavement unless through “ incidental “ contact.

Having replaced many many exhaust over my middling club racing “ career “ due to running out of grip because of ambition usually outweighing my talent made this an easy diagnosis. Good eye, though !

I saw pics of Ducati's long pipe during early testing but nobody seemed to know if it was possibly a distraction or something real.  It was on Bastianini's bike so it must be for real???  Any thoughts?

Given what Pecco has said about the 22 engine being abrupt or too harsh I think the long pipe was an attempt to calm the engine, bring the torque peak down, maybe at the expense of a bit of top end, which they can afford. I also think it didn't work. "Let Jorge and Johan figure it out", Gigi says, "Pecco you go back to 21 binky. Jack, are you still here?"

I'm gonna be a divider once again and say I LOVE the Gresini colors. Damn that looks good to me. Race bikes SHOULD be bold unconventional colors IMO. Kawasaki racing green with Muzzy, Lawson, Rainey et al, Yellow with speed blocks, Blue and White for Cooley. We gotta get back to bright colors. The times are too gray for black bikes, let's have some sunny, optimistic colors for a few years. Woohoo!

Even if you win the lottery, as far as I know they're all in museums now and not available. And there were only, what, five or six of them built? Despite my addiction to bikes and racing, that's the only bike photo on the wall in my study (rather grandiose name for a re-purposed bedroom).

This Britten device has consumed a portion of my brain since seeing it on the CYCLE WORLD cover in 1992. Pure passion and ridiculous engineering. If only there was a way for GP racing to go back to it's roots and wasn't such a business while still allowing David to report on it while earning a decent living. Heaven on Earth! I recently shed some tears of joy and nostalgia while watching a video of Michael Dunlop doing a commemorative lap of the Isle of Man TT circuit on a Gilera 500/4.