PlanetMinis Forums banner
101 - 120 of 129 Posts

· Registered
Joined
·
8,957 Posts
Interesting Observation Josh
But I would not discount Daves input overall as he not only has experience with Car drag racing , Builds race cars and exotics for a high end shop , he has been tuning bikes since the 70s as well.
Wasn't trying to knock him, just pointing out why that particular example didn't translate to this scene. I'm sure if we had a chance to chat about that build he'd bludgeon me to death with experience of the ins and outs of firing order changes on exhaust scavenging, etc. Plus he's likely gotten to play with motors with enough torque effect going on that the cam design has to take into account altered timing at one end vs the other at WFO...
 

· Registered
Joined
·
2,424 Posts
Your example is flawed. Both motors did in fact put out the same HP, as the dyno correctly reported. The reason why one configuration went down the strip faster than the other is because the car is traction limited in that scenario. The altered output pattern was 'lumpier' which gave the tire a moments rest between pulses, that recovery time actually makes a difference in it's ability to stay hooked up. This is why you're seeing motorcycle mfgs like Yamaha returning to 'lumpier' motors setups like the cross plane R1. To make the cross plane motor Yamaha had to ADD weight and parasitic power losses in the form of a counter-balancer that a normal flat plane inline 4 doesn't need. It doesn't make any more power, but it does allow a good rider to make more use of it at the extreme edges of traction.

Our minis already put out nice lumpy power, and aren't tire limited on pavement (lumpy output traction gains don't translate to knobbies in dirt) so the motor making the most area under the curve on a dyno in a pitbike is going to be the quicker one on the track as well.
No the 'Dragster" had no traction issues.
 

· Registered
Joined
·
8,957 Posts
No the 'Dragster" had no traction issues.
Awesome, so I can just jump in, put the go pedal to the floor, wait for it to bounce off the limiter and then slide my left foot to the right to let the clutch out as fast as possible and it'll just hook up and go? Sweet, all the fun of dragracing minus that pesky traction management challenge! :p
 

· Registered
Joined
·
2,424 Posts
Awesome, so I can just jump in, put the go pedal to the floor, wait for it to bounce off the limiter and then slide my left foot to the right to let the clutch out as fast as possible and it'll just hook up and go? Sweet, all the fun of dragracing minus that pesky traction management challenge! :p
actually no. they dont let just anybody run these cars. You would need a licence first. sportsmen class dragsters that run on gas use automatic transmissions.They leave the line in a controld way.They use a transbrake with a 2 step rpm limiter. These cars are deadly consistant. They usually run within .01 et. It is a controled automatic setup.
I really dont care if you beleve me, cause im guessing you dont.
 

· Registered
Joined
·
1,208 Posts
not that i want to get involved but two motor that make the exact same power in the exact same vehicle with exact same conditions and driver inputs does not mean they will run the same times.......multiple things come into play to get down the track like traction stated before but also things like how fast the motor spins up(think about pulling a weight off a flywheel on a mini, your making the same power but the motor revs up faster getting into the power band quicker)......and auto transmissions are better for drag racing(always launches at same rpm, always shift at the same place, and shifts wwwaaaaayyyyyy faster then a human can)
 

· Registered
Joined
·
8,957 Posts
actually no. they dont let just anybody run these cars. You would need a licence first. sportsmen class dragsters that run on gas use automatic transmissions.They leave the line in a controld way.They use a transbrake with a 2 step rpm limiter. These cars are deadly consistant. They usually run within .001 et. It is a controled automatic setup.
I really dont care if you beleve me, cause im guessing you dont.
In that case one of two things is occurring:

If traction limited, firing order will impact available traction and how much power can be put to the ground.

If NOT traction limited, the change in firing order altered the output of the car which the dyno will absolutely show. The peak numbers may be the same but the shape of the curve may have changed, etc. If not traction limited, and the dyno output didn't change... something else had to have changed to alter the run times, especially if the cars are as consistent as you're saying.

And yes, I know about licensing, etc, I play in lots of motorsports circles too so I'm used to that, I was obnoxious to make a point.

What sanctioning org are you running under? Quick googling show lots of various classes fitting into 'sportsman' racing under some of national groups, with no specific class to target I wasn't up for searching for the needle in the haystack to read up on the exact cars you're playing with. With the consistency you're talking about, seems like you're running more of a bracket targeting game than shooting for absolute lowest strip times? Poker vs War as it were?
 

· Registered
Joined
·
8,957 Posts
not that i want to get involved but two motor that make the exact same power in the exact same vehicle with exact same conditions and driver inputs does not mean they will run the same times.......multiple things come into play to get down the track like traction stated before but also things like how fast the motor spins up(think about pulling a weight off a flywheel on a mini, your making the same power but the motor revs up faster getting into the power band quicker)......and auto transmissions are better for drag racing(always launches at same rpm, always shift at the same place, and shifts wwwaaaaayyyyyy faster then a human can)
On the flywheel front, changes in flywheel mass DO show up on a dyno! It may be subtle, but the change in driveline inertia does get picked up. The flywheel change will let you spin up quicker, but once you dump the clutch you'll have less momentum to draw off of for that initial surge, and less flywheel effect results in less torque so your usable powerband will be narrower, ie you've got to regear to match. I went through this with my last motor, with a standard flywheel it could pull 16/30 gearing, switch to an IRK and I had to drop to 16/42 to get it to move without fanning the clutch to death.
 

· Registered
Joined
·
2,424 Posts
The car is a bracket car class is called super pro. The car funs in thr 7.70 range. Is a dyno a great tuning tool? Yes one of the best. Im not the one that came up with the Dynos dont go down race tracks. I herd Warren Johnson say that "no i dont know him" but i herd him say that he made more power on the dyno but his car didnt pick up. Remember a dyno gives HP and tq but dose not simulate changing gears aerodynamics ect. Just like a flow bench , if you get better numbers there is NO guarentee the motor will make more power. It cannot simulate the pulses of an engine. Both of these are Very RARE though. as a PM member who is NOT SELLING SERVICES or really anything, im saying you do not need a dyno to build a fast engine. I use RIDER FEEDBACK that usually works good enough for me. This is just a hobby for me and im just trying to have fun. But the dragster really did make the same dyno numbers and it was at the rear wheels.
 

· Vendor
Joined
·
10,894 Posts
Discussion Starter · #111 ·
These things rip

Customer feed back:
Sup Vince,
Thought I'd drop you a line & let you know that I took the bike to it's first race & it worked beautifully.
Got 2 first place finishes on it, one against Aaron Yates(Rides for Eric Buell)!
The thing pulls like a freight train! Destroyed the competition! Scary fast! I attached the points sheet for the season so far.
 

· Vendor
Joined
·
10,894 Posts
Discussion Starter · #114 ·
Why I can't find this V2 head in your website?
We have the V2 China head for 120-150cc round cam cover motors with larger stud pattern
We will post news about re-stock of new shipment of V2 heads for Honda 50/70 and round cam cover china motors with small stud pattern as soon as we have an update , and put them back up online
 

· Registered
Joined
·
101 Posts
We have the V2 China head for 120-150cc round cam cover motors with larger stud pattern
We will post news about re-stock of new shipment of V2 heads for Honda 50/70 and round cam cover china motors with small stud pattern as soon as we have an update , and put them back up online
I saw there is a TB 88/108cc V2 head upgrade kit - TBW9102, does this head will fit on TRX90 engine?
 

· Vendor
Joined
·
10,894 Posts
Discussion Starter · #117 ·
I saw there is a TB 88/108cc V2 head upgrade kit - TBW9102, does this head will fit on TRX90 engine?
We had TRX90 kits listed , these are sold out right now
We will post news about re-stock of new shipment of V2 heads for Honda 50/70 , TRX90 and round cam cover china motors with small stud pattern as soon as we have an update , and put them back up online
 
101 - 120 of 129 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top