An interesting engine conversion - flat plane to cross plane four cylinder

[Sac Arrow]

@Ted will appreciate this. I'm wondering if he might try to do the same on one of his rides.

 

[Ted]

I'll have to check that out later. But I am a fan of the Yamaha cross-plane 4-cylinder crank in the R1,. It's not just about how it sounds (which I do like better) but the reduction of secondary vibrations (granted at the increase in primary vibrations) and what that allows. I hate standard flat-plane 4-cylinders in their sounds, vibrations, general driving characteristics. I haven't ridden the R1, but quite sure I'd like the engine.

For thoughts that this is new, it isn't really. The original cross-plane V8 goes back... 90?ish years, and was basically for the same reason, reduction in secondary vibrations. It proved more popular with consumers and that's why it's been the standard since then.

 

[Sac Arrow]

Which... works in a V8 engine. The cost of a reduction of secondary imbalance in a four comes at the expense of primary imbalance. But the interesting thing in the video is not just to test cross plane vs. flat plane in a straight four, but more so the ghetto means that they used to achieve it.

 

[Spring Ford]

This image from the film shows the firing intervals. 90, 180, 270, 180, crank angle. I can't imagine this ever being acceptable in a normal road car. I have read what I can about uneven firing intervals being applicable to bike racing and there seems to be some traction advantage connected with having a larger tire recovery interval between some pulses. I would think it must be pretty small.

My guess is it's use on the road is like the past popularity of the V10 engines with the likes of BMW. Sure, it had the best packaging for F1, where every single percentage point counts, but no discernible advantage in a road car. Win on Sunday, sell on Monday.

Now of course a true hooligan racer is welcome to use whatever they wish. On road or track

 

[Sac Arrow]

They basically hacked a crankshaft in to four pieces at the main journals, welded it back together and reground it, did the same to the camshaft, and actually got it to work.

 

[SoonerAviator]

This image from the film shows the firing intervals. 90, 180, 270, 180, crank angle. I can't imagine this ever being acceptable in a normal road car. I have read what I can about uneven firing intervals being applicable to bike racing and there seems to be some traction advantage connected with having a larger tire recovery interval between some pulses. I would think it must be pretty small.

My guess is it's use on the road is like the past popularity of the V10 engines with the likes of BMW. Sure, it had the best packaging for F1, where every single percentage point counts, but no discernible advantage in a road car. Win on Sunday, sell on Monday.

Now of course a true hooligan racer is welcome to use whatever they wish. On road or track

View attachment 126606

1, 2, skip a few . . .

 

[Ted]

This image from the film shows the firing intervals. 90, 180, 270, 180, crank angle. I can't imagine this ever being acceptable in a normal road car. I have read what I can about uneven firing intervals being applicable to bike racing and there seems to be some traction advantage connected with having a larger tire recovery interval between some pulses. I would think it must be pretty small.

My guess is it's use on the road is like the past popularity of the V10 engines with the likes of BMW. Sure, it had the best packaging for F1, where every single percentage point counts, but no discernible advantage in a road car. Win on Sunday, sell on Monday.

Now of course a true hooligan racer is welcome to use whatever they wish. On road or track

View attachment 126606

There have been a small number of odd-fire engines in road cars, there was a GM odd-fire V6 in the… 70s? 80s? that I recall. I agree that the traction benefits that have been discussed in motorcycles wouldn’t really apply in road cars, and the visceral characteristics are, let’s face it, irrelevant for 99% of car buyers. Motorcycles tend to be a different market.

I don’t recall the V10s being odd-fire but I’m certainly not an expert on them.

 

[AV8R_87]

In the 90's Audi was competing in the German version of stock car racing with a flat-plane V8 that they claimed was made by "twisting" the stock cross-plane crankshaft. Scrutineers decided that was pushing the rules too far.

 

[Sac Arrow]

They actually did this one first before the cross plane modification. They cut a Lada crankshaft, and welded it back up so that all four pistons move up and down at the same time, and reconfigured the camshaft and ignition so they would fire all at once.