17.5 vs 27t
03-07-2008, 02:24 PM
#16
Tech Fanatic
iTrader: (6)
03-08-2008, 07:17 PM
#18
I dunno about the novak 17.5 being exactly comparable to a good 27t in a touring car considering we can't tune the 17.5 which is good if everyone is running it but bad if it can't keep up with the ultra fast stock motors out there which will just keep everyone running brushed.
I was running on a short track today at 3.52fdr and a guy with a tuned 27t would pull me by 7 or so feet per 100 foot straight so almost 7% faster and had the same rip out of the corner that I did if not more.
Unfortunately 50 was the largest pinion I had at the time but I'll try some bigger pinions next week, there was a decent difference from 49 (3.59) to 50 (3.52) though I will admit. There was another guy running the same lrp speedo and novak 17.5, geared somewhere around 4.2 and we were almost dead even everywhere.. quite interesting.
I was running on a short track today at 3.52fdr and a guy with a tuned 27t would pull me by 7 or so feet per 100 foot straight so almost 7% faster and had the same rip out of the corner that I did if not more.
Unfortunately 50 was the largest pinion I had at the time but I'll try some bigger pinions next week, there was a decent difference from 49 (3.59) to 50 (3.52) though I will admit. There was another guy running the same lrp speedo and novak 17.5, geared somewhere around 4.2 and we were almost dead even everywhere.. quite interesting.
03-08-2008, 07:24 PM
#19
by the way, rollout for 3.52fdr is 57.12mm for the math challenged if you figure a 64mm tire which I believe most of the rubber tires are.
50 rollout would be about 6 pinions down from 50 for me, surprised to read of someone getting thermal shutdown at that point.
50 rollout would be about 6 pinions down from 50 for me, surprised to read of someone getting thermal shutdown at that point.
03-08-2008, 10:15 PM
#20
I ran my 17.5 today and was very pleased. I was just as fast as guys at my skill level whether they were running a 13.5 or 17.5 (yes the 13.5's were faster but I had a lot more control on the technical parts of the track and I wasn't blowing turns). I ran a 3.69 fdr (96/52*2) and ran a fast lap of 13.3. I went down a tooth to a 3.76 fdr but I didn't feel any difference in the car and ran a 13.2. This was on a 100x36 track (http://kenjikerins.com/the_track/ <= pics by chicagokenji).
**Side Note: After 12-14 minutes I thermaled. I didn’t have a temp gun so I had someone check the temps after my runs and I was at 135-140 degrees. Not sure if his temp gun was correct or not.
I realized as we start running smaller spurs and larger pinions we may need to drop 2 teeth to really feel the difference. Unfortunately I didn’t have a 50 tooth pinion with me to test this.
Here is a chart showing the percent difference using a 96 tooth spur (17.5) vs. a 115 tooth spur (27T) through a range of pinions.
(Example: 96/49 combo is 2% less than 96/50)
Just some food for thought….it’s midnight here and my mind is on my day at the track...wow what’s wrong with me!
**Side Note: After 12-14 minutes I thermaled. I didn’t have a temp gun so I had someone check the temps after my runs and I was at 135-140 degrees. Not sure if his temp gun was correct or not.
I realized as we start running smaller spurs and larger pinions we may need to drop 2 teeth to really feel the difference. Unfortunately I didn’t have a 50 tooth pinion with me to test this.
Here is a chart showing the percent difference using a 96 tooth spur (17.5) vs. a 115 tooth spur (27T) through a range of pinions.
(Example: 96/49 combo is 2% less than 96/50)
Just some food for thought….it’s midnight here and my mind is on my day at the track...wow what’s wrong with me!
Last edited by PitNamedGordie; 03-09-2008 at 07:41 AM. Reason: Trying to clarify...
03-09-2008, 07:07 AM
#21
I don't think we're meant to run for more than 5-6 minutes. brushless or not
03-09-2008, 07:20 AM
#22
03-09-2008, 08:02 AM
#23
Our club has been primarily a stock motor club for the last 20 years. We decided to skip ROAR STOCK and just go to ROAR SUPERSTOCK 2009 rules. Reason being is we did not want to slow down the class or speed it up, but the risk of slowing it down was more of a consern then speeding it up... We have a spec class for going slower. What we intend to do with running superstock2009 rules is to also allow the 27T motors and 17.5BL motors..
Another consern i have hear about is the difficulty i gearing a 17.5 as in some cars run out of gear before the motor is where it needs to be.. another issue we did not really want to deal with...
We start our superstock2009 rules this summer with buggy and then our TC's come this fall./.. Very excited
Another consern i have hear about is the difficulty i gearing a 17.5 as in some cars run out of gear before the motor is where it needs to be.. another issue we did not really want to deal with...
We start our superstock2009 rules this summer with buggy and then our TC's come this fall./.. Very excited
03-09-2008, 09:13 AM
#24
Our club has been primarily a stock motor club for the last 20 years. We decided to skip ROAR STOCK and just go to ROAR SUPERSTOCK 2009 rules. Reason being is we did not want to slow down the class or speed it up, but the risk of slowing it down was more of a consern then speeding it up... We have a spec class for going slower. What we intend to do with running superstock2009 rules is to also allow the 27T motors and 17.5BL motors..
Another consern i have hear about is the difficulty i gearing a 17.5 as in some cars run out of gear before the motor is where it needs to be.. another issue we did not really want to deal with...
We start our superstock2009 rules this summer with buggy and then our TC's come this fall./.. Very excited
Another consern i have hear about is the difficulty i gearing a 17.5 as in some cars run out of gear before the motor is where it needs to be.. another issue we did not really want to deal with...
We start our superstock2009 rules this summer with buggy and then our TC's come this fall./.. Very excited
03-09-2008, 11:25 AM
#25
Good plan on the superstock 13.5t/19t rules, the track that I race at would rather run brushed motors because they're faster at this point and they will never think about running 19t or modified. There are only a few guys running stock at the top levels and they just happen to have the fastest brushed motors and will not be convinced to run anything else. Maybe I can prove them wrong with some crazy gearing but really 3.52 is getting down there pretty deep I would think.. the motor never really felt hot to the touch though so if speedtech restocks pinions I'll buy something bigger.
Don't give up on the 17.5 just yet. I TQ'd and won
We have noticed that late in the race the 17.5 seems to fade a bit. I'm at 3.95 and my motor temps are 150* after 5 minutes. I'm going to experiment w/less timing and external fans. This should keep the motor cooler later in the race. In the first minute or two the 17.5 is just as fast as the brushed....I think it gets hot and starts to fade at the 3 min mark. I had a 3 second lead w/2 mins left and the brushed motor almost caught me at the line. My car was very good and I didn't make any mistakes, I think it was the motor that allowed him to catch up.Superstock sounds great to me...I have a new 13.5 Tinity Duo that I want to run. We just need everyone else to buy in.
FYI, race results can be found here:
http://www.jlapracemanager.com/cgi-b...re=HobbyTownSA
In 1/12 my 17.5 stayed very consistant the whole 8 minutes, geared at 87.5mm rollout.
03-09-2008, 11:35 AM
#26
Brian, we will be 13.5/27T no 19T. Thus the reason we are skipping 2008 superstock rules and just going right to the 2009 and run brushed 27 with 13.5 and 17.5 if someone chooses...
19T had a few years of really strong showing here but then died off. We primarily run stock rubber TC
19T had a few years of really strong showing here but then died off. We primarily run stock rubber TC
03-09-2008, 12:36 PM
#27
The Novak heatsink pulls a LOT of heat out of the stator. I notice the motors will fade late in a race if the stator gets too hot. Bob Novak said they can only handle so many "flux cycles" before they saturate and begin to lose power.
The Novak heatsink is different than fans or the clamp-on type because it's a force fit, directly on to the stator. It actually replaces the center ring and pulls out a lot of heat. Just be sure to use a heat gun when you put it on, and make sure it's in the position you want, 'cause it don't move once installed.
The Novak heatsink is different than fans or the clamp-on type because it's a force fit, directly on to the stator. It actually replaces the center ring and pulls out a lot of heat. Just be sure to use a heat gun when you put it on, and make sure it's in the position you want, 'cause it don't move once installed.
03-09-2008, 12:54 PM
#28
Brian,
Don't give up on the 17.5 just yet. I TQ'd and won We have noticed that late in the race the 17.5 seems to fade a bit. I'm at 3.95 and my motor temps are 150* after 5 minutes. I'm going to experiment w/less timing and external fans. This should keep the motor cooler later in the race. In the first minute or two the 17.5 is just as fast as the brushed....I think it gets hot and starts to fade at the 3 min mark. I had a 3 second lead w/2 mins left and the brushed motor almost caught me at the line. My car was very good and I didn't make any mistakes, I think it was the motor that allowed him to catch up.
Superstock sounds great to me...I have a new 13.5 Tinity Duo that I want to run. We just need everyone else to buy in.
FYI, race results can be found here:
http://www.jlapracemanager.com/cgi-b...re=HobbyTownSA
In 1/12 my 17.5 stayed very consistant the whole 8 minutes, geared at 87.5mm rollout.
Don't give up on the 17.5 just yet. I TQ'd and won
We have noticed that late in the race the 17.5 seems to fade a bit. I'm at 3.95 and my motor temps are 150* after 5 minutes. I'm going to experiment w/less timing and external fans. This should keep the motor cooler later in the race. In the first minute or two the 17.5 is just as fast as the brushed....I think it gets hot and starts to fade at the 3 min mark. I had a 3 second lead w/2 mins left and the brushed motor almost caught me at the line. My car was very good and I didn't make any mistakes, I think it was the motor that allowed him to catch up.Superstock sounds great to me...I have a new 13.5 Tinity Duo that I want to run. We just need everyone else to buy in.
FYI, race results can be found here:
http://www.jlapracemanager.com/cgi-b...re=HobbyTownSA
In 1/12 my 17.5 stayed very consistant the whole 8 minutes, geared at 87.5mm rollout.
Were you running lipo or nimh? at the end of the run I recharged my lipo 3200 pack with 1570mah so I shouldn't have been anywhere near a voltage drop.
I'll skip the super stock class, I don't need 3 brushless motors now that I've already purchased the 17.5 to run stock with you. I'll run mod with you guys all day long though since my lrp came with the 3.5t.
03-09-2008, 12:56 PM
#29
Brian, we will be 13.5/27T no 19T. Thus the reason we are skipping 2008 superstock rules and just going right to the 2009 and run brushed 27 with 13.5 and 17.5 if someone chooses...
19T had a few years of really strong showing here but then died off. We primarily run stock rubber TC
19T had a few years of really strong showing here but then died off. We primarily run stock rubber TC
03-09-2008, 01:30 PM
#30
Im talking abou ROAR legal 27turn motors. Only going by what our local racers tested in there own cars, they claimed that that the 13.5 was a touch faster then there good CO27 motors and that the main thing was consistancy from run to run.. Many our our CLUB racers said they where just more consistant but not nessarily faster..ITs a risk no doubt but for our club at this moment, guys are looking to lipo and BL for even more plug and play racing... Guys are getting lazy(my self included) and just want to show up on race night and slap the car on the track... So decided to go 13.5 as our evolution of the current 27T stock class....