2.5L Rocket Stroker Engine Kit with 6 Speed Transmission (R&D)

While we're waiting on the 2.5L components' lead time...

6th Gear Update


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Research is done and the new 6 speed tranny parts are designed.
We have found a way to fit 6th gear in - without compromising any existing gears.
6th will be the thickest cogs in the box.

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I wasn't aiming for a certain rpm at say 80mph - we'd have to take what we get,,, as we are retrofitting an additional gear, and there are constraints like what diameter cogs we can fit in, and constant mesh gears with fixed centres so not a lot of options for teeth numbers.

Won't bore you with the technical challenges overcame :) but here's the way it has worked out;
  • • Calculated to run 2200rpm at 80mph
  • • Theoretical top speeds are (wait for it!) 225mph @ 6300rpm,,, or 320mph for 9000rpm engines

Other ratios calculated either a diameter that won't fit, or a ratio that makes it unfeasible to have a 6th speed (i.e. revs only drop a modest amount at ~80mph vs existing 5th's 3000rpm).

So we have settled on this 2200rpm @ 80mph and 225mph top end for stock rev limit ratio gearing, to proceed into operational testing.



Currently we are 3D printing the new stage 1 hybrid prototype gearbox for operational testing by hand and tweaking.
By hybrid I mean it's the OEM metal gearbox with the new 6th gear parts fitted in plastic.

Next update should be a video demonstrating the prototype box in operation, proving the concept, toggling through gears!

Stand by :thumbsup:
THE 6th gear is not going to improve 1/4 mile performance or top speed in real world riding
 
Anyone fancy a 2500cc Rocket Stroker Engine Kit?

And/or a 6 speed Rocket transmission?


That is the vision.


Step 1: Build an R&D testing engine from spare parts to run on a bench


This is the construction of the R&D Test engine, which will be used to facilitate & test engine enhancements such as above. It's made from spare parts I've accumulated over the years,, e.g. block fro an 06 Classic, head from a 2010 Roadster, throttles from a silver engine 06 Classic, clocks from a 2013 Roadster, ECU from another 2013, and so on.

Been planning this for a few years now, in fact @warp9.9 may recall some conversations from 2010/11 (before I even had a Rocket) where I was picking his brain about possibility of stroking the engine, and some other stuff.



Original plan was;

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Had the spare engine since 2012.. as its first job, it was used to facilitate Carpenterizing my daily driver.
Have been gathering the other spares since to run the R&D engine.

Anyway I did 1 & 2, even though i had the spare engine since 2012 I kinda skipped 3 & 4 and went straight to 5 (except changed mind to supercharger instead of turbo for a few reasons).

I see a lot of folk who would like a 2.5L, 6th gear in their bike (me being one), but nobody has done anything on it afaik.

It's going to be an expensive venture, it will take a LOT of time.
I'm prepared to go through with it just so I can have it, and if anyone else wants a kit too (once R&D is complete and the kit is proven and solid / after I've done the guinea pig duties..) that would also be welcome.


The plan would be to have multiple trims of the kit available too - you could go for same materials that are in the stock engine, you could go for high end/light/stronger metal if you're a power maniac, you could go for low compression ratio (8:1) if you want to go boost, or you could go for high compression ratio (~12:1), same goes for the tranny, you can go basic material or full on high end indestructible material.

I don't know if the 6 speed is possible in this block - we will see. Might have to go another route that's thinking outside the box :)

On Roadsters at least the GPS has a 6th gear position already on it. I found this 6th gear the time my GPS went faulty. Getting 6 gear maps made from Dynojet for map-by-gear ain't a problem.


But I believe it is entirely achievable to move up to 2.5L... that's not much to ask.
i hope it can all be done just with stroker crank, rods etc. But if we also need to bore out the cylinders and fit thinner liners made from stronger metal and fill them with different pistons.. well so be it.

The Rocket cylinders are 765cc each, with a diameter of 101.6mm and stroke of 94.3mm (an oversquare motor). If we increase stroke length (that's what she said) to 101.6mm to be perfectly square, the engine CC will rise to 2,472cc (or 2.5L :D).

If we go all the way to 2499cc, stroke length would need to be 102.7mm, an undersquare motor.

Reckon there will be a downside to the stroker though - higher piston speed for the same revs as stock engine. This might limit us in terms of top engine speed - the 9000rpm redline mightn't work, might need to limit to 8, 7 or even 6k rpm. But the torque increase/lower down and increased fuel economy might be worth it for some..

Thinking the kit would look like:
> Stroker crank
> Matching balancer shaft
> Journals, bolts, wrist pin circlips etc etc
> Stroker conrods
> TuneBoy & TuneECU maps
> OEM-looking 2500cc badges to replace the 2300cc ones
> Pistons if needed



Step 2: Get R&D engine running

Almost there, got a couple of faults to fix;

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Step 3: Measure up engine & transmission internals

Step 4: Design new components

Step 5: Get new components made

Step 6: Install & trial new components......


Anywho, been dying to get stuck into this for years,,,, so here I go :)
IT could be the NEW ROCKET will be 2500cc and have a 6 speed trans
 
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