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

[Neville Lush]

Random comments...

I have confirmation that we can get longer rods from Carrillo rods.

I reckon you would need shorter rods if the stroke is increased. It may be possible to raise the gudgeon pin in the piston a bit. Crank IS ONE piece. You MAY be able to get say 6mm stroke increase if one could find a rod with a smaller big end eye and offset grind the crank 3mm. The crank would need to be hardened/nitrided before the final few thousandths are ground off. To bore out a R3 engine one would have to bore the lower part of the block so a thicker sleeve could be fitted and then make a larger diameter rebate in the top of the block surface. All of these things are possible with the addition of $$$. I have yet to find a person who would wish to pay for this.

 

[Claviger]

I too have been looking into spare engine blocks and a displacement increase After examing components and speaking to knowledgeable engine builders these are my thoughts;

The cheapest way to get more torque/power is increase volumetric efficiency fooling the engine into behaving larger than it is but this is complicated and filled with trial and dyno testing Not cheap or easy
The cheapest way to increase the displacement in this engine is to increase the bore The cylinder liners once pressed out of the block are a sophisticated alloy with ribbing and a hard wearing coating They are thick .These could be easily replaced with a suitable thinner custom solid sleeve of larger internal bore .LA sleeve company will do custom sleeves
If more bore was desired the block would need to be bored 2 or 3 mm to enable yet larger sleeves
Doing the above could potentially give an engine with 3 to 5 mm more bore
A few problems have to be dealt with .
First of all cylinders like these do not have the longevity of the original hard slippery material of the stock engine
Secondly the pistons would have to be specifically designed and built with a piston company that could keep piston weight identical to the originals by short wrist pins judicious weight milling design and material
The above would minimize changing the original R3 excellent balance and design of the crank rods and counterbalancers Vibration problems would be minimal if any.The crank rods and counterbalancing is complicated and changing any of these components would be tricky costly and limited to small displacement increases anyway compared to the bore option
Thirdly though the bore can be easily increased the seal of the bore with the head area might have to be redesigned slightly or o -ringed to seal perfectly
I had the heads on my stock engine flow tested and the results were basically excellent They can support a lot of horsepower in stock form and dont seem to need much porting to increase flow Flow rises in proportion to valve lift linearly to .450 lift and beyond
To accomodate a larger engine larger titanium valves and mild throat blending would be the route to follow if modest valve lift were to be retained
properly done this approach is the right one for 1)size of increase(2.7 litres possible)
2)ease cost and complexity
3)ultimate HP potential of engines.Increasing displacement doing bore increase is usually near double that of stroke increases

this engine doesnt need 6 gears
More gears in the same space would compromise the beef just to make space and a weaker trannie
The more torque you have the less gears you need
What about a lower differential final ratio This could give you relaxed top gear engine revs and the increased displacement would make even a taller gear effortless

Increasing bore will be insanely expensive.

 

[Penner]

Are you sure?
Increasing bore to 106mm - that should be no problem - will take capacity to 2495ccm. That is a plus close to 9%.
You need 3 steel liners, three pistons and a head gasket.
In Germany you can get that parts costum made at about 1500€.
Long stroke would be much more...

 

[Claviger]

Nikasil, without it, you’d be making a big mistake. Just my opinion, but there’s a reason the Daytona 955 spins to 11,200 happily and the speed Triple, with the same bore and stroke was cut way short on RPM.

CP has already told me they can move the wrist pin upwards 4mm if requested, they’ve also said they’re able to adjust rod length fairly easily.

A set of -2mm length rods and +4mm height pistons will set you back around $1,900.

 

[Penner]

1900 and you don´t have a modified crankshaft yet.
The 1050 Triumph engines are mainly long stroked 955s. That is about the 10% it is reduced in rev limit.
I don´t think, that the lower rev limit is caused by the material of the liners.

 

[Claviger]

I meant 955i S3 vs 955i Daytona. It was long accepted that nikasil was the primary reason they capped the 955i S3 lower, but, also the cams stopped making power over about 10,000.

It may be that as I was told is totally wrong, and the nikasil has nothing to do with RPM, but I doubt Triumph would have gone to the expense if it didn't have something to do with it.

EDIT:

Just got off the phone with Falicon, they're confident they can stroke our crank without any issues, 3mm o offset, being very attainable. Full stroking work is $545 for a dealer and $750 for a retail customer, including the regrind, chamfering the oil passages, journal polish, shot peen, and chemical treatment. Sending them a rod and piston will allow the balance it all, which is another $250, and personally I wouldn't even attempt a stroker R3 without balancing it since you're changing both rods and pistons.

So, for full stroker kit, for retail customer, we're looking at around $2,900 for the rotating assembly. When you consider the cost of top end work, it's really not THAT much to gain 5-7% torque across the board (assuming you're doing your own labor).

 

[barbagris]

I have yet to find a person who would wish to pay for this.

Nev - meet Rob (aka @Claviger )

 

[Penner]

You are right. There was the Daytona 955 model up from 2002 that already had some 1050 features like shim under and really lovely cams.
Stock rev limit was 10800. That is 1350 over the 1050-engine limit.
Afaik already the high revving 885 S3 Daytona had forged pistons, that the lower revving models did not. I don´t know if the rods were different.
What I know about nicasil coated alloy is that is has less problems with different expansion ratios in the motor, less wear and gets rid of heat better than steel.
I have never heard about higher rev limits. But you never stop to learn...

What about taking it to 2650ccm with more bore and stroke? If you are doing pistons anway it is just the liners and gasket.

 

[Claviger]

At 11,200 we found valve float on the dyno last Thursday on my 2002 Daytona. The piston speeds there are pretty low (for a bike), and the rod to stroke ratio is extremely high, the bottom end would take 12000-12500 I think.

Concerning the boring, honestly, I just plain don’t think it’s a good idea. In all the years of being a motor head guy, most bottom end problems I’ve seen with highly modified motors were traced back to boring it larger.

I could be wrong, but I think the R3 would benefit more from longer stroke than bigger bore if displacement were equal between the two motors. The valves being slightly less shrouded would be great, but, I think not as great as the increased stroke allowing for more cylinder filling.

Just my wild ass scientific guess lol.

 

[Paul Bryant]

One thing that concerns me (Tho' the blown Engines don't seam to have a problem) is that the Big End Journals are not that large, they are a heap smaller than the Trident ones, and that's only a small Engine.
Just what is the longevity of a bored and stroked Rocket going to be ?
Again how do the Blown Engines last ?