sorry to do this
09-25-2008, 07:32 PM
#46
Tech Rookie
Hey guys,
want some advice im completely torn between two engines for a replacement in my mbx6
now these are the only 3 im considering after running some others, i dont normally ask these questions but id like other peoples info on them
rb ws7 3 l2g
os v spec/speed
Team orion crf
the only downside to the speed is the cost in the uk 280gbp!!!
What do you chaps think, im after run time reliability life span and ease of tuning.
want some advice im completely torn between two engines for a replacement in my mbx6
now these are the only 3 im considering after running some others, i dont normally ask these questions but id like other peoples info on them
rb ws7 3 l2g
os v spec/speed
Team orion crf
the only downside to the speed is the cost in the uk 280gbp!!!
What do you chaps think, im after run time reliability life span and ease of tuning.
The OS Speed tuned 21 is hard to beat for all around performance, but I would suggest trying to find an old style GRP Ninja 21, I have one with 14 gallons on it and it still screams. 14 gallons! thats unheard of, you will not get that kind of longevity from an OS Speed, or any other engine that I know of. The new Losi GRP's are having issues with the conrod's, and Losi isnt offering to warranty it so be careful there.
09-26-2008, 11:00 AM
#48
The slug weights added to the crank of a Speed have little or nothing to do with its low end performance, however, they have all to do with it being one of the smoothest running (NO VIBRATION) motors on the market. On the breakin bench nothing moves on the table. Simply amazing. Even a coffee cup has very minor ripples in the liquid.
Ed M.
Ed M.
09-26-2008, 11:02 AM
#49
I think he is trying to say what your trying to say..just in his own way...... Calaber finds the Speeds low end to be smoother and more tractable as compared to the standard VSpec...We run both motors and you can definitely feel the Speeds weighted crank when you are running on a low traction situation, the VSpec will break loose much easier then the Speed will.......with the Speed you can lay into the throttle much harder with much less worry of spinning out...... However on high bite surfaces you can definitely feel more punch from a standard VSpec.......Just like when I lighten a crank on a motor, its can be awesome if you have traction, or it can be a nightmare on low traction surfaces......
When i was running V specs i ran a Eb modded speed in my buggy, and a regular Eb modded in my truggy. For this ^ reason
the speed also makes a lil more top end
Last edited by jpalessi; 09-26-2008 at 11:13 AM.
09-26-2008, 11:25 AM
#50
Tech Addict
I think he is trying to say what your trying to say..just in his own way...... Calaber finds the Speeds low end to be smoother and more tractable as compared to the standard VSpec...We run both motors and you can definitely feel the Speeds weighted crank when you are running on a low traction situation, the VSpec will break loose much easier then the Speed will.......with the Speed you can lay into the throttle much harder with much less worry of spinning out...... However on high bite surfaces you can definitely feel more punch from a standard VSpec.......Just like when I lighten a crank on a motor, its can be awesome if you have traction, or it can be a nightmare on low traction surfaces......
Ed M.
09-26-2008, 11:30 AM
#51
While I agree that the Speed has a smoother lower end (throttle wise) I want to attribute it to the difference in carbs and other minor tweaks to the engine more so than the slugged counterweight. I know the weighted counterweight plays a part, just not sure how big that part is. Not even sure the difference total weight betweenthe two crankshafts. Guess I need to drag out the scale next time I have one down.
Ed M.
Ed M.
the carb is the same thing, just a different body w/ the idle screw recessed on top. flows the same..
09-26-2008, 11:41 AM
#52
Tech Addict
If the combined flow rates on the carbs are truly the same for similar openings then it would fall to the crank being the reason.
Ed M.
Ed M.
09-26-2008, 11:48 AM
#53
09-26-2008, 12:05 PM
#56
09-26-2008, 12:07 PM
#57
You can also use a weighted flywheel, it will have a similar effect... When I used to run a road car I used to use a ultra light flywheel, the effects from heavy to light flywheel are pretty dramatic.. As well the effects are exponentially more apparent the faster the rate of acceleration of the engines RPM....in a 1:1 car the ;ight flywheel will feel like a 40% increase in power in first gear, but on the highway in 6th gear there is no noticeable difference between heavy and light flywheel.......... how this applies to 1/8th scale and traction is most apparent when a machine loses traction, a light rotating engine will spike up RPM very fast, whereas a heavy rotating engine will have more inertial resistance to overcome before the RPM's will spike up...On a slippery track you will definitely feel the effects of a weighted crank as opposed to stock, and it is especially apparent if you run a really light crank on a slippery track............ on a side not I have had the luxury of trying to drive my road car on ice with both a light flywheel and a heavy flywheel... the light flywheel made you feel like a "one legged man in a ass kicking contest" LOL even with fancy winter tires there was no way to properly drive the light flwheel..... however with the heavy stock flywheel the car had exceptional traction with the very same tires....
09-26-2008, 12:20 PM
#59
The big difference between the 2 is the rotating assembly weight.
The heavier assembly will start spinning slower, but when it does get up to rpm.. it will spin faster then the lighter assembly. hence less bottom, and more top
With the lighter assembly you'll get the opposite affect.
The heavier assembly will start spinning slower, but when it does get up to rpm.. it will spin faster then the lighter assembly. hence less bottom, and more top
With the lighter assembly you'll get the opposite affect.
09-26-2008, 01:05 PM
#60
Mega go for the JX21 its way cheaper than the speed has a treated crank and runs really strong, the vspec carb restrictors also fit so if you still have them its a bonus also, it uses the .28 case to prevent problems with the case spliting at the bottom, personally i cant sway toward a speed for financial reason but i would go std Vspec or the JX21.
