XP big bores - lets compare

[Idaho Slim]

who ran Tom Mots BB engines in xp 163's. Both guys made the trip to the dyno, revealing 169hp.

um, serious question here .............. Isn't that number kinda weak ???

 

[MARCUSO]

um, serious question here .............. Isn't that number kinda weak ???

That's 2 away from B.J.'s. Who knows what other goodies were or weren't on..

 

[Leaf27]

You started it

I have 2 posts in this thread. Not sure what you have to do with it.

Montanapowder, I run jaws twins on my 860BB with the stock 08 ECM. Running pump gas @ 4000' - 6000' with no issues. Seems like when you mess with the ECM problems start.

 

[gus bohne]

um, serious question here .............. Isn't that number kinda weak ???

DJ hit it dead..2.5 grams per arm, and more aggressive ramps..thats torque !

dyno results are so very very dependent on the operator and the method of test.

a variation of 7-10 % is the norm..

see snowgoer article "truth in dynoing " done by myself and Olav 1993.

Kelsey and John are on here spreading the tuning knowledge and "opening the books" of what they will provide you,, no getting out of anything with them..

100% stand up guys..

I feel there are many others too, some may let some lower end pass thru but NO shop , oem or aftermarket provider is capable of making everyone happy or always winning the shootout..

Gus:

 

[Dynamo^Joe]

Over years of doing clutching, have been fortunate there are percentage (mind you its very small) of tuners who get their engine on the dyno and get to run before and after, or only after engine mods.

I am not engine savvy nor know much about clutch setups, however I think I am savvy (can get around a bit) regarding clutch theory. My experiences when a tuner has to throw on flyweight with an hp increase, something beautiful has happened.

If 169hp and that torque is considered weak, I can't comment on that I don't know if it is or not. I just know that 275 lb guy and add on gear, what he did ain't too shabby.

 

[Idaho Slim]

Thanx, guys. From all the stories of riders that have the 880's and saying its superiority to a 860, (which I did not swallow) I had expected a higher output number, specially with 20 cc's more and producing less.

I have first hand experience of the Torque of BJ's motors, which when clutched to that torque curve, are a VERY impressive machine!!!

 

[gus bohne]

Slim..
Once the bore size gets out over 860 the transfers are not going to be able to be modified enough ( due to durability of casting at that large diameter).

The expected gain would be small or moot as the integrity of the cylinder itself is compromised to a great extent. I would question the bore even being capable of holding its shape at that size ( 880 ).

I should state that in my end use of turbo, flatland, ice drag 21-25 psi boost...My customers need a stout overbuilt cylinder,, i.e. no big bores on the 800 series 3 engines over 84mm..

109lbft torque is what the 800 open mod snox had.. damn hard to ride and friggin tiring too..!!!

try hanging on at 190 lbs ft of torque,,swweeet !!@24psi,, launching on ice 136'' prostock rev chassis.. 1.12 60' times , @ 12 psi launch boost..4500rpm engagment..

THATS FUN !!!

 

[RED995]

DJ that number of 169hp, correct me if i am wrong but i believe both of those sleds were 860's with single pipes and stock reeds. I know first hand that Toms 880 with twins and a couple other little goodies are making 176 real world reliable hp. No whether or not thats better or worse than the next guys im not sure. Tom,Ralph,Engine Tech all build good engines the pnly reason i listed these 3 is i have first hand experience with these 3 and have never played with anyone elses product. Deaner there is alot of great info in this thread im sure you'll find what your looking for.

 

[DaveB]

I have first hand experience with name #2 on your list and I can assure you it pulls a solid 150hp....just like the stocker.

 

[Dynamo^Joe]

DJ that number of 169hp, correct me if i am wrong but i believe both of those sleds were 860's with single pipes and stock reeds. I know first hand that Toms 880 with twins and a couple other little goodies are making 176 real world reliable hp. Now whether or not thats better or worse than the next guys im not sure. Tom,Ralph,Engine Tech all build good engines the pnly reason i listed these 3 is i have first hand experience with these 3 and have never played with anyone elses product. Deaner there is alot of great info in this thread im sure you'll find what your looking for.

From what I know, "no goodies" so then yes, correct. Single pipe/stk reeds and at 8100 rpms.

 

[renegadefred]

Wow , whay a post, 25 pages and 20000+ click after, lots of info on here! My question is how does the stock (weak..) crank handle all that power on 860 BB because a lot of stock motor go down by crank bearings or crank failures? Never modded a sled but when rebuilt time will come maybe a BB or drop in RKTek kit could be a option. I know pistons are better on those kit but the stock crank??

 

[MontanaPowder]

BB reliable

I have all season on mine. Ran two RKTEK drop in kits several thousand miles and not a single problem. We ride em like we stole em. It seems the better pistons are a advantage. Had about 4000 miles on last 800 and the xp has about 2500 miles.

Hope this helps.

 

[portgrinder]

Tom at Mot's is a good dude. He builds good engines that is for sure. 169 is pretty damn good. esp if it was dynoed at Neil's...thats a very very strong number relative to the rest of them.

 

[Insaneboltrounder/sjohns]

Is NPP doing a pipe for the xp?

 

[NoSecondChances]

um, serious question here .............. Isn't that number kinda weak ???

As gus said, operator and method will vary and produce slightly different #'s, as well as dyno elevation, most AB dyno's are over 3000 ft, so you are losing a little off the top right away. I would say that a BB with a stock single and stock reeds at 3000' in the 170 HP mark is decent.

NSC

 

[Insaneboltrounder/sjohns]

I thought dynos always corrected to sea level?

 

[winter brew]

I thought dynos always corrected to sea level?

They do whatever the operator tells it to do

 

[NoSecondChances]

I thought dynos always corrected to sea level?

See WB's response above. My comment wasn't all that clear I guess (didn't have the morning coffee yet), but I guess my point was an 860 with single pipe is making close to the same power as most stock 1000's, I would say that's not too bad for a moderate 60cc increase. Dyno #'s are what you make of them, and it really comes down to a lot more than the dyno run.

A few yrs ago, AC came out with the 700 and said it was making 148 HP. When we looked at the BSFC values for the dyno, they were into the 0.4's at peak power....you'd be lucky to get 1/4 mile down the trail before KABOOOM!!! at those #'s. I would rather have a moderately tuned sled with 10 less HP and a way broader power curve, than a high strung peaky HP figure in a very narrow powerband. Besides all that - you don't hillclimb a dyno.... So enough about who's 860/880 makes the most HP on the dyno, let's get back to the regularly scheduled discussion.

Who's kits are using forged vs cast pistons?

NSC

 

[Leaf27]

.

Who's kits are using forged vs cast pistons?

NSC

Cast here

 

[portgrinder]

Is NPP doing a pipe for the xp?

If one makes power, I would think so. He's going to play around with my 09 stocker and my bb as well.