m8 big bore

[ridinginstyle]

looking to start a thread for the big bore guys plus learn a little more about the kits out there. bpm, speedwerx, d&d, rkt, ect...

one question I have is why does the speedwerx 925 only make 170hp when everyone else is around 190-195hp and have less cc's.

 

[minet]

imo, speedwerx is always conservative with their hp claims ,, if they make one at all. and conversely other shops might be more generous ,, just an idea
i run their 925BB:700 on my trail sled and have been told it is 170 hp also in current config. but you hear of 800BB;700s claiming that also.

 

[m8magicandmystery]

195..hp...???...well im certian that your looking at kits with full race porting ,when i questioned those numbers with Bikeman they told me that those high hp numbers were not with the trail reliable package...i think all the m8 to 900 bigbore packages are safely in the 170 to 175 range

 

[ridinginstyle]

I hope someone that runs SW 925 will come on here and tell us how it runs. It just seems like there would be no point to big bore for 170hp when you can just mod the 8 to make the same.

Thats why the new D&D 901 kit has my interest with 193hp and 124ftlbs with a single pipe on pump gas. Now that seems worth while!

 

[Rprecision]

Sounds like you need a M1000 !

 

[Klimbing Kitty]

Like magic said ...many different types of porting or bore and that only counts for part of the HP. If your sled is not set up right...clutching, fuel, pipe, y-pipe, belt, on and on. And you have the balls to run your sled as lean as possible without blowing it up you will never see the high HP numbers.

 

[m8magicandmystery]

. It just seems like there would be no point to big bore for 170hp when you can just mod the 8 to make the same.

!

peaky vs torqey hp..??..isn;t the big bore safer hp then modding the base 800 to get the same horsepower..

 

[ridinginstyle]

peaky vs torqey hp..??..isn;t the big bore safer hp then modding the base 800 to get the same horsepower..

Of course it is. But with the new 800 at 160hp why would anyone spend 2-3 thou just to have ten more horsepower over that.

I just really want to hear from people using the big bores and hear what they have to say about how well they work. There is like 15 different turbo threads with all sorts of feed back , and with BB's being a little more affordable we could use all the info we can get.

 

[m8magicandmystery]

well all said and done my bigbore /ported and compression head with ceramic dome and coated pistons..cost around 4300 canadian with exhaust and stm valves etc ,etc..and i like my bigbore...probably 175 hp....i may go with twins....but for certain if i wasn.t shy of the turbo i would go there.what i really like as well as the bigbore for the performance is as well shedding 90 lbs from the sled...the last 25 from the timbersled skid arriving soon...the bigbores seem reliable...nitrous is maybe the next step or many people with bigbores had luck putting a turbo on as well....remember my 800 only had 143 hp stock...you guys getting the new ones are lucky...i would invest into the carbofibre skid and a arms etc etc for performance gains if the 160 hp numbers are right

 

[Sledslutt]

All said and done my BB cost the same as my turbo. They are not cheaper... especially if you have to use race gas. BB's do not come with all your gauges that you will require and copious amounts of other things. Just my experiance though and I am in Canada.

 

[RACINSTATION]

First, do not confuse the M7 Speedwerx 925 kit with the M8 kit. For the M7 we used new billet cylinders and heads....basically a new engine from the crank up. This motor was rated at around 180HP. It is a nice package and is a little finicky. The M8 to 925 kit uses the stock M8 or Crossfire/F8 cylinders and a modified head. It uses the same pistons that the 925 billet kit uses, but with the M8 you have different port timing and a different crank.

The M8s bored to 900-925cc run really strong. D & D has a 901 Kit as well. It is VERY impressive when running against the M1000.

The stock cylinder big bores start out around $2000.00 then you add the gauges and clutching and fuel controller and your are running it up around $2800.00.

Pump gas turbo kits are around $5000.00 with gauges and clutching. Maybe a bit more with an install.

Apples to apples, the big bore runs about half the money and about a quarter of the increase to your horsepower numbers. You can run a big bore on pump gas if the port timing and head are corrected for it. Hope this helps.

 

[Klimbing Kitty]

I'm going to have to start shopping where you do Racinstation. My 1200 BB cost me $4000 plus $800 install. and my new race gas turbo just cost me $5000 and I will do the install with a buddy. Maybe the 1200 BB is a little more costly but i did not even get to keep my original cylinders?

You are totally right though tha taking an 800 up to a 900 or 925 is not worth it. 700 up to a 9 is maybe and a turbo on an 800 is a hell yah!!!!

 

[likkerpig]

RKT M7 to 800 bigbore is 1850 (plus install and gauges if you so desire) Not an apples to apples comparison (800vs925) but should put numbers in the ballpark. I think a lot of the extra expense is in the billet cylinders, you reuse the stock cylinders and it should (logically) be less expensive.

 

[ACMtnCat]

RKT M7 to 800 bigbore is 1850 (plus install and gauges if you so desire) Not an apples to apples comparison (800vs925) but should put numbers in the ballpark. I think a lot of the extra expense is in the billet cylinders, you reuse the stock cylinders and it should (logically) be less expensive.

That $1850 only gets you half of what you need though!

What about Pipes, EFI fuel box, EGT's, Clutching?

If you pay someone to install all of it, your up into the $3500-4000 range!

Turbo starts to sound like a better choice! But thats another $3000! +

 

[ACMtnCat]

looking to start a thread for the big bore guys plus learn a little more about the kits out there. bpm, speedwerx, d&d, rkt, ect...

one question I have is why does the speedwerx 925 only make 170hp when everyone else is around 190-195hp and have less cc's.

Cutler has a great BB 800 for the m6 and m7. I'm running one on a m6 and would estimate it at 175-180hp. She RIPS!

 

[Klimbing Kitty]

That $1850 only gets you half of what you need though!

What about Pipes, EFI fuel box, EGT's, Clutching?

If you pay someone to install all of it, your up into the $3500-4000 range!

Turbo starts to sound like a better choice! But thats another $3000! +

Thats what I was talking about. and if you think you are going to run a modded out machine without gauges your crazy

 

[F_ast]

Your other option in all this mess if you want/ need more power is to run something like the D&D shim kit for the 800's. Its a shim for under the cylinders to increase port timing (which is very close to the new 800ho) and some head work, all for less that $400. Just send in your head as a core. Can be setup to run 87, but 91 is recommended. Hearing Dyno number of 155hp on 87 and close to 160hp on 91.

Where do you think Cat got the idea to increase port timing and a new head design?

 

[likkerpig]

How far you go into bigbore world is your call- you can run Kelsey's m7-8 BB with stock pipe/can and be fine WITHOUT fuel control and/or gauges. Not saying it's smart to roll without gauges on a mod anything...but the option IS there to do so with that particular engine "package" and configuration.

Of course you go deeper into the BB woods, throw twins in there add another grand, BD box another 400, installation costs if you don't do it yourself, and yes, you're not too far away from turbo pricing.

Just for the sake of discussion, what's easier to tune- bigbore or turbo?

 

[MCIVER]

does anyone have info on the D&D 901 kit, sounds pretty impressive !
has anyone seen one run?

 

[fasta76]

TTT