Hello All, I'm new to the forum,

I have an '03 Sprint that I bought 6 months ago with 6,600 miles on it and I've put another 750 so it is about time to start thinking about modifications (my wife has a rule that you have to drive/ride it for 1,000 miles before you can tear it apart). My question is:

Has anyone investigated retrofitting the 1050 crank into a Daytona 955i engine? Are there issues relative to the cases that prevent doing so? As an alternative, is there any problem fitting a Daytona 955i head on the 1050?

Building the Daytona stroker seems more advantageous because the balancers are sized for a lighter mass. It should be possible to replace the pistons, rods, pins, rings, etc. with lighter specialty parts and get a 1050 with the same rotating mass as a 955, thus retaining the balancers. Yes I know it wouldn't be cheap.

Also if anyone has had their head flowed or has seen flow bench stats published, I would appreciate having the information. I would like to run some simulations to estimate the exhaust system size and cooling requirements, but without some real numbers it is pretty crude guess work.

Thanks and I'm enjoying reading all your comments

I'm not sure but I seem to remember that the 955 and 1050 are substantially different. To the extent that the cylinder centres are not the same. That would negate the cranks being interchangeable - wouldn't it?

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Chris

"Panniers can never hold everything you want, but they CAN hold everything you need."

Fortunately I haven't bought a motor yet, so it can be anything. Speed Triple Motors seem optimum, but not very plentiful. The simulations I've run to-date indicate that the Daytona cams are pretty good but there is probably some more to be had without losing driveability. Of course, without real port flow numbers that isn't much better than a guess.

Whatever I finally settle on, I thought I would swap out the liners, pistons, pins, rods, valves, valve springs, guides, seats, bearings, etc. for lighter race-quality parts. After all, once you are going to to pull an engine apart and have the head ported you might as well do the whole thing. There might not be much of a gain depending on the quality of the factory parts, but I haven't found much detailed information about them and I haven't had any success yet locating an experienced tuner of Triumph triples in Southern California.

If anyone has had an engine balanced and knows the weight of their pistons and rods, I would be interested in knowing. I would also be interested in knowing piston pin bore height, pin diameter and length, rod length, crankshaft journal diameter, etc. And since I'm asking I would also like to know the valve stem length and diameter, the stock valve spring free length and coil bind height, and the valve spring seat pressure and pressure at maximum lift. Generally I would expect to find this kind of information in the shop manual, but it is conspicuously absent. In fact given the level of detail provided by the shop manual, maybe the quality of dealer service isn't so hard too understand. But that is another subject...

Yes the big motor has a nice, flat torque curve until it starts to run out of breath, so I agree that the Daytona cams would likely make a big difference. It would be nice to have the extra RPMs on occasion though and that woould require some upgrades. Thanks for the graphs, very interesting.

I know very little about the physics in changing an engine for performace (other than the basics). But I do know that a friend of mine swaped out the 08 busa crank and put it into his 04 busa (vance & hines built) motor to give it a stroke. I dont know how hard it would be, but maybe using the bottom end of the 1050 motor and using the forged top end parts(piston, conn. rod) of a daytona motor would work and be a very nice setup..... You could also try and stroke a 955i motor. If possible, it is a good idea...although splitting the cases involves alot of work....

I have also found that there are more parts in common on the 955i and the 1050 than I thought... It could be possible...

Racecomp, could you go into a little more detail on what you did to the motor to get it to almost 140RWHP?

Chris

Has anyone messed with timing?

Did you find anything or??

I take it that it is a secret or?

Sorry I haven't been keeping up with the board, had to work, etc.

Net out is: 1050 is a stroked 955, bore centers, are the same. Daytona heads have larger ports and valves and correspondingly more aggressive cams and larger exhaust pipes, all of which moves the power peak higher up in the RPM range. Note that Daytonas also have shot-peened rods and wrist pins to cope with the higher RPM. They also have coated alloy cylinder liners, which make their 955i engines 2 kg (approx 4.5 lbs.) lighter than a 955i Sprint's.

I haven't been able to find out anything definitive about the piston geometry of either the 955 or 1050 engines. I suspect that the 1050 may have an altered compression height that would prevent fitting the higher lift Daytona cams due to interference. Nor have I been able to find out anything about rod lengths or weights, ditto for piston weight, skirt geometry, etc. all of which would be key to determining if new pistons are worth the expense.

I have two dealers reasonably close and I have asked them to let me know if/when they tear down an engine so that I can come over and mike some parts. Whether they will or not is anyone's guess seeing as how there is really nothing in it for them.

I do know that the engine technology is now fairly far behind the state of the art, which is not surprising since the design is twenty-some years old. For example it still uses a thick, relatively high tension ring package. And the valve springs are conventional, constant-diameter-cylindrical form wound from round wire and not even Chevy does that any more.

Unfortunately, there doesn't seem to be anyone who has tried to bring our big triple up to current technology standards. South Bay Triumph in LA has some experience with the Bonneville and some people are racing the 675, but mostly it is unknown territory as far as I have been able to learn.

If anybody knows anything different, I would certainly like to know.

By the way, I noticed in reading through some older posts that some people were experiencing premature wear of the piston pin bores. If I was rebuilding an engine, I would definitely replace the wrist pins and have the new ones DLC (diamond-like carbon) coated. NASCAR cup engine builders were never able to eliminate pin galling issues once their engines began to see 9,000 RPM until they started to DLC-coat wrist pins. It is now a standard practice and pin problems are pretty much a thing of the past. The pin bore does have to be clearanced for the coated pin because there is a measurable build-up, but any competent machine shop can do that.

Just my $0.02