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

[Stillserving]

Re trade offs, a guy who souped up Volkswagen motors, of all things, told me once, I can get as many hp as you want, just remember a dragster engine only has to last 4 seconds.

Especially in regards to air cooled VW motors! The guys dragging those usually use NO COOLING, other than a box fan blowing over the motor between runs.

 

[R-III-R Turbo]

Step 2: Get R&D engine running

Almost there, got a couple of faults to fix;

Finally got time off to go play again, P1690 CAN Fault fixed, this was the little bugger hidden in the middle of a 2010 main harness;





And then the R&D bench engine 1st startup:

 

[RocketmanBristol]

Are you wanted by the police Turbo?

 

[Claviger]

I did some poking and prodding last night, looks like a new crank baffle plate will be in order, somewhat expected.

The bed plate doesn’t look to be an issue it’s just the wings on the baffle/scrapper that look to get too close.

 

[R-III-R Turbo]

Step 3: Measure up engine & transmission internals

2.5L Stroker Update

So after rolling the R&D engine over and tearing it down with impunity, we found that there is ample space around the moving crank and rods to permit a stroker engine. Loads around baffle plate and liner and skirt and rod clearances.

To cut to the highlights, it gets pretty tight in a couple places; the gearbox crankcase wall at halfway between TDC and BDC for throws 1 & 2, and between the crank counterbalances and the balancer shaft.

Tightest gap I found was 3.0mm, which would kill the proposed +3.65mm crank throw increase,,,,, but I have a clever idea (or at least i think it is ) to make the +3.65mm happen. If it works better than intended, more than 2.5L will be doable with just crank and rods.

This is how a sad-act like me spends his holidays;



Throw increase of 3.65mm brings stroke up from 94.3mm to 101.6mm to net 824cc per cylinder (up from 765), making a 2472cc or 2.5L engine.

Just to reiterate, the idea behind 2472cc and not say 2499cc, is that the bore is 101.6 so bringing stroke up to 101.6 also will make a "square" engine, like a Dodge Viper or Bugatti Chiron.

Also found a fabricator who is making the side panel badges, so they're OEM looking but say 2500cc instead of 2300cc.
Yeah it's a lie as it's 2472cc and not 2500, but the OEM badge says 2300 when it's actually 2294 (2295 by my calcs), so fcuk the po-lice!


Verification of stock displacement

Done some research on piston speeds and apparently about 25 m/s is more or less the industry standard for max piston speed in sporty engines, but can be around 20-21 for big pistons like ours;

• Stock Rocket III (94.3mm stroke, 6300rpm) = 19.80 m/s
• 2017 Dodge Viper (100.6mm stroke, 6250rpm) = 20.96 m/s
• 2018 Bugatti Chiron (86mm stroke, 6700rpm) = 19.21 m/s
• Gen II Hayabusa (65mm stroke, 11500rpm) = 24.92 m/s
• BMW S1000RR (49.7mm stroke, 14200rpm) = 23.53 m/s
• Yamaha R6 (42.5mm stroke, 17500rpm) = 24.79 m/s
• Typical F1 engine (42.3mm stroke, 17900rpm) = 25.24 m/s
• 9k Carpenter Rocket (94.3mm stroke, 9000rpm) = 28.29 m/s
• 2.5L Rocket III (101.6mm stroke, 6300rpm) = 21.34 m/s

I guess, for me, running a 2.5L Stroker Supercharged Carpenter engine at 9000rpm will mean peak piston speed of 30.48m/s which is a bit above what factory engineers would like.. but maybe race engine builders probably would be too afraid.
6300rpm guys will be 100% safe at 21.34 m/s.

Figure if the engine spends its life below 6500 then what's the difference - occasional jaunts up to 9000 might be harmless

Starter map is ready, 2 minute job, added 8% air across the board in the F trims and applied to both F and L tables. My estimate - 2472cc is about 8% more volume than the stock 2294cc, so 8% air quantity added to F tables.
And 101.6mm is about 8% more stroke than the stock 94.3mm, so estimate is 8% more vacuum pulled, for the L tables. It's a place to start at least.


So now we're in the middle of Step 4, design new engine parts.
I've spec'd up what is required - won't post until the design is final with the approved vendor.
A number of crank & rod fabricators in both UK and USA have been engaged, so we'll see what the damage is...... it's not looking good though, most of the $$$$$ is for design and setup costs




6th Gear Update

I may be a bit of an idiot,,,,,, but upon opening it up it became apparent real quick that Triumph used parts from a 6 speed gearbox - look at the detent wheel;

It has 7 positions, 6 gears + Neutral!
We only use 1-5.

And the selector drum it indexes around to change gear has a convenient "blank" space between 5th and 1st, for the future 6th gear fork track!

Plus the GPS has the same 7 positions also! (have a photo somewhere of gear 6 on the tacho display)

Clearly, the box is structured like a 6 speed tranny, but with 5 pairs of gears in there.. guess Triumph wanted thicker gears to take the torque etc, but why is 4th so thin or maybe 5 gears was just because marketing said so.

So now we have the track map design of the new selector drum;

Ever want to see Rocket transmission in action?

Also gone out to a number of gearbox masters in UK and USA with the proposal, initial estimates are it will be like 10 G's to do the 1st one but cheap thereafter.

But my plan is to shave 1000s off that by designing/building the prototype myself from aluminium, just to prove (to some degree) that it will "work", before cutting real gears and modifying shafts.
More on that later.

Art.

 

[Claviger]

You have indeed been busy sir!

Now you see why I said it's a 6 speed with the gear cut off for 6th gear, the parts are mostly present already.

Were you able to get a measurement between the bottom of the big end cap on the rod and the crank bed plate? That was the one area I was not able to get to, but I did take delivery on an extra bedplate to have it shaved in those regions as a precaution.

The increased stroke will increase the vacuum un-evenly, but, 8% should get it running well enough to get on a dyno, I expect more like 10-12% in certain areas where the stroke is most effective, the mid-range.

 

[barbagris]

"Cry 'Havoc!', and let slip the dogs of war"

 

[R-III-R Turbo]

Step 4: Design new components

Step 5: Get new components made

UPDATE: 2.5L BILLET STROKER CRANK, RODS & BALANCER NOW ON ORDER!

Hopefully land in time for Christmas...

 

[torki pig]

"Cry 'Havoc!', and let slip the dogs of war"

the stuff dreams are made out of.
Thoughts:
I hope the balancing calculations were accurate so extra vibration non existent
The standard injectors and heads are probably getting marginal if you plan to use the high rpm capabilities. Probably boring the injectors as Claviger did for added top end a good move.
Torque will be proportional no problem.
Any idea of total rods and crank cost?
To a degree longer duration cams are a cure for enlarged engines
Congratulations and thanks are in order for stepping up and doing much more than the bench racers .
Claviger should be along shortly picking your brain.

 

[warp9.9]

UPDATE: 2.5L BILLET STROKER CRANK, RODS & BALANCER NOW ON ORDER!

Hopefully land in time for Christmas...

You getting the end drilled and threaded so you can add the suppercharger to her