| Author | Message | ||
     Carbonbigfoot |
I was just looking at the dyno charts from my bike, and thinking about what it would take to get a significant increase in horsepower from this platform. Seems to me, we're back to the good old displacement and RPM factors. We might be able to get a bit more bore and stroke from this block, but what about lightweight pistons, rods, bad-a$$ high strength cranks, etc., and getting another couple thousand rpm? With the powerband looking like it does, it's not even letting up when it hits the rev limiter. Now, believe me, I understand as well as anyone that we have entirely adequate power for the street. No way I can ride this thing to the limit (and still have a license...). I may have missed it on a previous conversation, but does anyone know if there was any developmental work at either Buell or Rotax to do a burn test on this motor? You know, spin it up till it grenades? This is more thinking about what it would take to get toe to toe with the big D. The chassis could handle it, and even if you're talking about several thousand dollars in parts, what could this motor do? Rob (Message edited by Carbonbigfoot on March 21, 2009) | ||
| Carbonbigfoot |
Anybody here actually fragged a motor on one of these? Like a rod or a piston? R | ||
| Ridenusa4l |
I showed my dyno sheet to several people and they all said, " man that thing doesnt even stop making power, it needs more rpm." I too have been wondering about wat if it actually went to the 12000rpm on the tach, what could the possibilities be??? Jake | ||
| Court |
>>>> if it actually went to the 12000rpm on the tach, what could the possibilities be??? Use caution lest thy whirly gadgets seek communion with the sun. . . . | ||
| Ducxl |
I have a 1k twin that has run to 12k  It's old too. Buell needs a 2250r to race the "big D" Actually,i'm sure there's plenty of power to be had.It's just,nobody currently supports that.Unless,you possibly possess a race license?  | ||
| Jmr1283 |
well at stock redline ur pistoned speed is 4651.5 fpm . which is rate there for a save long lasting motor. move it to 12000 and ur in the range of ahdra drag racers who dont expect more then 150 passes of a engine. 5316 fpm way to much for us. even 11000rpms is too high for a street bike that wants to see 20,000 miles. it comes in at 4873fpm. now for using forged pistons and billit cranks and h-beam rods. u might be able to bump ur rev up to 11,000rpms but ur still living on the edge. | ||
| Fast1075 |
OK....more revs are out...time for the turbo...or some juice... | ||
| Duggram |
What about a good exhaust, ECM tune, maybe bore out 3 mm, raise compression, porting, etc? | ||
| Clarkjw |
Dual stage shower head fuel injection; and a non EPA compliant exhaust should do the trick. A bore to 1200cc should be next step. Then titanium bits and the like. Desmodromic valves anyone? (Message edited by clarkjw on March 23, 2009) | ||
| Hitman44139 |
IM going to do a port and polish... just to see. Want to get this Race ECM set up..... | ||
| Duggram |
What would a non EPA compliant exhaust be? Are you refering to something like the BMC race exhaust? | ||
| Wfo_rey |
I saw the light and found speed Thanks DAVE & Mr MM   | ||
| Rfischer |
"port and polish.." Polishing, if you mean smoothing the intake passages, will do nothing for power. Porting on the other hand has the very real potential to reduce torque and make hp. peaky. Bigger ports are not necessarily the way to increased power for the simple reason that it can reduce intake charge velocity which is a bad thing. Explanation: 80% of charge-air cylinder fill occurs at less than 50% of valve lift. Reduce velocity and you decrease cylinder fill at lower valve lifts, in effect lowering torque and moving hp. up to higher revs and valve lift. Maybe a good Dyno-Queen but useless on the street or track. Something to ponder: if you bolt a set of 883 Sportster heads on a stock Big-Twin Evo [you can with a little machining of the fins to clear the differing pushrod tube angles], you will pick up 20 ft.lbs./hp. with no other changes. The smaller 883 ports dramatically increase port velocity in the Big-Twin which increases power. You can pretty much rest assured that Buell and Rotax have maximized the port velocity for the 1125 at the present bore/stroke configuration. Much can be done with fuel/spark tuning in conjunction with intake/exhaust mods, but porting is a slippery slope with limitless opportunity for unintended consequences. Beware. | ||
| Duggram |
Rfischer, great post. I did not know these things. Thank you. | ||
| Ft_bstrd |
Could there be a compromise solution instead of a "silver bullet". Assuming that HP and Bore have a linear relation, boring the engine to 1199 should raise the output about 10HP. Couldn't there be an increase in RPM limit to 11,000 or 11,250 and keep the piston speed within safe, workable limits? Would that give another 10HP? Fuel map and exhaust tuning? Would that be worth another 5-10 HP? | ||
| No_rice |
MORE POWER...  | ||
| Boltrider |
Port velocity has to do with port taper, correct? Like having a port that tapers down from inlet to outlet is good for air acceleration - I think that's how it goes. But even then it's still not that simple. (Message edited by boltrider on March 24, 2009) | ||
| Rfischer |
Partly taper, partly port shapes, partly manifold shape...but, yes, complicated and not for amateurs. Even so-called professional tuners will sometimes fixate on maximum port flow from flow-bench tests, missing the more sophisticated effects of velocity. A motor doesn't run on a flow-bench. (Message edited by rfischer on March 24, 2009) | ||
| 186bigtwin |
Well said, porting is not for amatures, a lot of development time is spent on max effort race heads to get the most airflow at optimum velocity. The best velocity is at around 0.77 mach or around 847 ft per second, any faster and the air will un-attach from the port floors and cause unwanted turbulence. Very hard to achieve, impossible without correct equipment....... | ||
| Jmr1283 |
i havent looked at the ports yet by the valve seats but lets say rotax is the same as harley with there heads once the head castings are done and its in the machining stage or lets back up they press the seats in some where in the assembly line. and theres always a miss match between the inside of the seat and the inside of the port walls making a step that the are has to go around. so there is gains at takin ur die grinder and flushin the seat and port walls up. might not be lots of gains but thats something a home mechanic can do no problem. thats if u hav the tools or want to tear the engine apart. this simple step can gain u power by decreasing turbulence. ive done it on all my other bikes. usually in winters that i dont have the money to spend of port jobs. oh and make sure not to hit the contact area for the vavle and seat. if ur lucky ull be able to hone it out. but usually it takes machining. depends what ur using at the time for a bit. | ||
| 186bigtwin |
Jmr1283, you're correct. almost all manufacturers are more concerned with building the engines as fast as possible, and don't care about each head or crankcase being exactly to "blueprint" it's too much trouble. Gains can be made smoothing up surfaces as you pointed out, maybe not too much but some gain can be realized. I'm sure soon some head shop will be offering "street" porting as well as max effort race heads, this pony really just got out of the barn. | ||
| Rfischer |
I believe the 1125 heads are CNC ported from the factory. That being the case, you will not find "mismatches" in the valve pockets. Please understand, these motors are not 60's small-block Chevys manufactured with 1950's technology. Applying conventional NHRA/NASCAR hot-rod tricks to modern small-displacement power-sports engines can easily produce unhappy results. What's going on inside the current crop of 1125/1098/999/etc. motors really is rocket science. Yes, increased performance can be found, but you'd better be a Rocket Scientist. | ||
| Zac4mac |
I used a Dremel and stones to port and flow my '76 Sportster heads back in the 80s. The castings were horribly rough. Butt dyno said big improvement. What I've seen of the insides of the 1125, there's VERY little if any gains to be had by that technique. Agreed Robin, rocket science indeed. Z | ||
| Court |
>>>>but you'd better be a Rocket Scientist. Everytime I read that I think back on the day I told the young kid . . "what are you a Rocket Scientist?" I got an e-mail "yes, sir I am. I am at NASA now but would really like to work at Buell". He is not working at Buell and an incredible Elf. It was right up there with the guy, who in the structural debate, asked Blake . . . "well just what the hell are your credentials"? Bad question. . . . . Blake started with his work on the B-2 Bomber and went on for a while. Case closed. The internet is a fun place. | ||
| Blake |
From aircraft to anchor bolts. Who knew? I still dig it. | ||
| Jeffb |
Do you guys know if anyone is looking at making internal performance parts for the 1125 yet? Specifically cams. Thanks, Jeff | ||
| Jmr1283 |
im diggin this nitrous express set up. cool cool. its a dry system so u just have to stick the jet part by the filter with the correct jet for the power ur lookin for. and instead of having a push button like ur shooting a rocket. u hook it up so u can activate it by hitting full throttle. i know sweet! im checkin this out a little harder. i know this engine could withstand a 15-30 shot | ||
| Georgehitch17 |
yea i would be interested in some nitrous like a 25 shot or something where would you put the tank though | ||
| No_rice |
im diggin this nitrous express set up. cool cool. its a dry system so u just have to stick the jet part by the filter with the correct jet for the power ur lookin for you go right ahead and run a dry system. i sure wouldnt but its not my bike. sure seems to me that alot more people grenade them with a dry system then a wet, and whats one more line and solenoid... on that note, remember this is a pretty high compression motor. not usually what you want for nitrous. not saying i'll never do it. just doubt i'll throw the same 50 shot on my 1125. | ||
| Fast1075 |
There is FAR MORE to a liveable nitrous setup than stickin a jet in by the filter for the power you want...in its self that is a guaranteed way to make an 1125cc doorstop....regardless of wet or dry systems, the engine needs particular attention to structural elaments (which it may or may not have from the factory) and a properly designed and tuned ignition controller as a minimum... Here's a hint...don't take any advice from anyone that refers to a system as NOZZ...(I wanna  when I hear that... Some of the fastest nitrous powered bike engines are based on low compression...while others have had success with c/r's in the near diesel range... Properly set up and tuned...a nitrous will give you the most bang for your buck of any power adder... I would love to have the money to do nothing but research...or better yet...get paid to R&D....and TTD... | ||
| Bigblock |
don't forget, nitrous oxide itself is NOT A FUEL!!! It is an oxidizer, what that means is it is like a chemical supercharger, it basically adds more air chemically. WHat this means is YOU MUST add more fuel. Unless you have an extremely rich pre-existing condition, just squirting nitrous in there is very likely to burn holes in pistons. Nirous also likes a lot less total timing, so it is also a good idea to have a way to dial your timing back a bit at the time of nitrous injection. BUT, you don't have to believe me or listen to me, I am not a nitrous expert. I did dragrace a nitrous equipped bigblock chevelle for a few years on the street and track, but the systems now are way more advanced then 20 years ago. |
