Our new track clone jr2 rules have us going from big pipe, no restriction, and 325 pounds, to weiner pipe, .550 restrictor, and 300 pounds. With the weiner pipe AND restrictor plate, any way to still get strong out of the corner with the reduced horsepower? We run a 12T driver and 66-69 sprocket depending on conditions. Help to drop to an 11T driver? How much will the pipe and plate rob from us?
Weiner pipe / restrictor plate
- Thread starter schoonie
- Start date
MikeleoneCT
Member
I'd go the other way with the gear. You'll lose mostly top end with the restrictions, probably don't want to try to run much over 5000 or so RPM's. It will rob a lot from you, I think the pipe is the bigger issue here. Is .550 a blue plate? If so, That would have been a big deal with a big pipe, only a little deal with the weenie pipe
My concern I think was not so much top end (we want that as well), but being able to romp out of the corner. He likes alot of umph if you will when he steps on it. we are just running an 1/8 mile track with fairly tight turn radius so holding it wide open is not a good option. We tried that with big pipe and no carb restrictions, just did alot better when we could get em out of the corner and first part of straightaways. Off the top of head I believe the .550 is the blue plate.
alvin l nunley
Site Supporter
I don't know much about ovals, but that seems like an awfully low gear for a 1/8 track.
12/69 = 5.75
a 1/8 mile track is 660 feet long.
12/69 = 5.75
a 1/8 mile track is 660 feet long.
CarlsonMotorsports
Site Supporter
Al, I think he's meaning that the oval track he competes on is 660 feet around (not long.) That gearing doesn't sound so awful if you look at it that way.
Dropping to the 11 driver will help slightly coming off the corner -- the more important reason to make the change though is to get the gear ratio correct.
-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
26 years of service to the karting industry
765-339-4407
bcarlson@CarlsonMotorsports.com
alvin l nunley
Site Supporter
Long?, Around?, the same thing to me. Did you really think I didn't know what he was talking about?Al, I think he's meaning that the oval track he competes on is 660 feet around (not long.) That gearing doesn't sound so awful if you look at it that way.
Dropping to the 11 driver will help slightly coming off the corner -- the more important reason to make the change though is to get the gear ratio correct.
The other point is that, knowing the length/around doesn't tell you the length of the straights or the radius of the turns. If the radius of the turns are 65', the straights would be 125' long each. I don't know what you or the poster call a tight radius, but I don't think a 65' radius would qualify as a tight radius. That means the straights would have to be even longer with tighter radius turns.
Taking one tooth off the engine, 12 tooth to 11 tooth, means you have to take 5 teeth off the axle to get the same ratio. I think this change would help, getting out of the turns, a lot more than, "slightly". Of course, if you change the 12 to an 11, you could change the axle to something in between a 66 and a 61.
i disagree with the not over turning the motor. If the track you race has tight turns with you lifting, you will want to crank the motor to keep it in the power band coming out of the corner.
On large tracks you don't overturn so the engine stays in the powerband but on tight tracks you do the opposite.
You might be surprised but often times when you add that restrictor on small tracks, you will be just as fast as you were due to the fact that you don't have to lift as much. I'd try the exact same thing you've been running then change from there depending on how it runs
On large tracks you don't overturn so the engine stays in the powerband but on tight tracks you do the opposite.
You might be surprised but often times when you add that restrictor on small tracks, you will be just as fast as you were due to the fact that you don't have to lift as much. I'd try the exact same thing you've been running then change from there depending on how it runs
CarlsonMotorsports
Site Supporter
Whoa! This coming from the same p.c. guy that constantly corrects others about suck/draw/vacuum vs push?
Ok, forgive me -- I thought you seemed confused by your post stating that it seemed to you like an awfully low gear for that track, followed by your statement that 1/8 mile track is 660 feet long.
TCash is spot on with turning the motor harder on tacks that you scrub more corner rpm. This is the exact reason that we offer two recommended peak rpms on our customer engine spec sheets - one for momentum tracks (lower peak rpm) and one for tracks that put the engine in a bind (higher peak rpm.)
Stunner Racing Engines
New member
Naturally, we can't give exact numbers but on a blue plate, the small pipe will cost you .5-.8 of a hp and the restrictor plate is almost 2 hp, so you're taking a pretty big hit in the neighborhood of about 2.5 hp or more. On tight tracks we still turn or small pipe blue plates around 6300 with good results. Good Luck!
racing promotor
Moderator
That sounds like odd gearing for a true 1/8 th mile with a clone, what kinda lap times are your turning with that 12 T combo ?
alvin l nunley
Site Supporter
I like to think of it as, “constantly reminding” others. New people come to this site every day, they may not have heard my ideas on push versus suck before, so that’s why I repeat myself occasionally.Whoa! This coming from the same p.c. guy that constantly corrects others about suck/draw/vacuum vs push?
Ok, forgive me -- I thought you seemed confused by your post stating that it seemed to you like an awfully low gear for that track, followed by your statement that 1/8 mile track is 660 feet long.
I wasn’t confused! 1/8 mile is, in my opinion, a pretty good size kart track. Do you disagree?
I have several 1/8 tracks laid out in my CAD/CAM program. I start with a given radius and then add straights so that the track measures, on the inside edge, 660 feet. The smallest turn radius so far is 55 feet. (110 feet measured between the straights) That gives it straights that are 157 feet long. A bit more than half the length of a football field. If that’s not a good size track for karts, in your opinion, how would you describe an 1/8 mile track? What gear ratio would you recommend for that kart?
Something else; with a 110 foot diameter turn, would a junior have to let off the gas? If the turn has a radius so small that even a junior would have to let off, that means the straights would be even longer.
Ever since I joined this forum, I have been asking people to describe their track closer than 1/8, 1/10, so on and so forth. To date, I have received no such information.
CarlsonMotorsports
Site Supporter
Al, I, like many others on here, refer to 1/8 & 1/10 mile tracks as "bullring" tracks. We race indoor tracks bigger than this quite often. I don't have the statistics, but I am thinking that most kart tracks are 1/6 mile and larger. 1/5 mile is probably the norm, with 1/4 mile being on the big side.
Now, with limited property and participation numbers, there are likely a whole lot of "backyard" tracks that are in the 1/8 and 1/10 mile sizes.
As for proper gear ratio, I am sure you are aware that this depends on several variables; track configuration (length of straight vs radius of turns,) engine output, tire size, amount of rpm loss/drop in the corners, amount of grip the track offers, and more. As a starting point, without a whole lot more info, I'd suggest being in the 12-65 range with his plate clone on a tight cornered 1/8 mile track.
Now, with limited property and participation numbers, there are likely a whole lot of "backyard" tracks that are in the 1/8 and 1/10 mile sizes.
As for proper gear ratio, I am sure you are aware that this depends on several variables; track configuration (length of straight vs radius of turns,) engine output, tire size, amount of rpm loss/drop in the corners, amount of grip the track offers, and more. As a starting point, without a whole lot more info, I'd suggest being in the 12-65 range with his plate clone on a tight cornered 1/8 mile track.
Owner lists it as just a tad under an 1/8th, but the 12-67/68/69 worked the best for us before the pipe and restrictor. We haven't had the opportunity to test yet to see what it likes, but will try these suggestions and see what we come up with. As always, I appreciate the wisdom and willingness to help on this forum. I have learned so much on here. Al, I will try to walk it out for you when time permits.
Stunner Racing Engines
New member
1/8 mile is a small track for us also. If a 12 tooth driver was working good for you before, I'd start with the 12/69 and just see where you're at. Good Luck!
alvin l nunley
Site Supporter
Starting with a 12/69 doesn’t sound all that unreasonable. You need to start somewhere.
Big, small, they’re both relative. It’s very possible I’m wrong, but a 60 foot radius turn, and a 142 foot straightaway, seems pretty big to me. Walk off 40 paces and you’ll see what I mean. Normal walking, with some practice, has one step measuring about 3 feet. 142 feet, the length of the straight, is just shy of half a football field.