The advice I will give is try to figure where you will eventually be. If you think you want to go mod buy an 8.5 or something around that range and dial the motor back, there are a few different ways to do that. If you think you want to run stock get a 17.5 or 13.5 and have a blast. I work on a sprint car and the only similarity I have found is that I simply have a better idea, and ability, to fix it when I break it.

To answer your question in simpler terms, the lower the number the faster the motor. That's just "in theory". you will find guys who will swear by this motor over that motor and suggest my 13.5 wupped up on their 8.5 blah blah blah but the simple answer is the lower the number the faster.
Have you run RC before? I only ask as 2WD mod buggy is an optimistic entry point but hell, go for it!!!!

for a new driver, here's the best way to explain WHY you want one over the other.

17.5 - easiest to drive because you use full range of motion with trigger.
13.5 - next easiest to drive because you use full range of motion with trigger, just go a bit faster
8.5 - uses less trigger range of motion because of the amount of power. If setup right, you will usually use about half of your trigger. Fast guys will be able to work in more than slower guys. Harder to drive when you have half the throttle range as the 17.5 and twice the power.

All in all, if you were only getting 1 motor, I would say get a 13.5 and add boost until you can make it around the track and be less than 1 second off the fast guys per lap. After that, move up to a 9.5. You will have more power than you know what to do with. I ran an 8.5 and wished I had bought the 9.5 instead because I would have been able to control it better.

did u seriously switch

a.e is the way.

Yeah, nothing lasts forever

I wanna see both sides of the coin. I ran two times a week with the 4.1 for a solid 6 months. Gonna give the 22 a shot for a while, learn it a bit, and hopefully be better off because I will know how to help guys with questions like I can with the 4.1

Not to mention I was planning on getting a new kit either way this winter

Thanks everyone for the quick and thorough replies. Yes, this will be my first time racing an r/c car, although my son has a t4.1 that I play with in the street. I know it is an aggressive move to jump right into mod 2wd buggy but 1) that is the primary class around here, and 2) my real race car sucks up all my $$$, so I only have one shot to get into this.

Zeakemedia, do you find that your car setup skills xfer to the r/c world? I am really good at car setup.

go 17.5 then if its your first car. Don't worry if you tell people thats what you have and they tell you there is no 17.5 class. You wont be going any faster with a mod so just learn to drive and then you'll graduate to mod later.

Well you will be back alot sooner then later!!

oh yea, 22 feels good but it isn't as fast.

durango drives closest to b4.1. still aint same.

LOL, you may be right, but I wanna play around a bit and see. I won't really get to try my 22 until the fall. Figure I'll give it a some time and then decide before Columbus in Jan.

I don't think I'm gonna get to p800 let alone 600 odd; how are the V2 shocks holding up in terms of leakage? Does one need to file/sand/replace the bushings to get a perfect fit? Do the O-rings rip as easy as it used to?

How do they compare to Kyosho's? Are the Prolines better than the V2s?

Thanks,

There's really nothing wrong with the V2's. Kyosho velvets are better shocks (smoother, leak less) but the V2's are pretty decent and fairly easy to maintain. Can't speak for the prolines. The springs on the V2's are pretty pathetic. Lots of folks are updating to big bore springs from losi or kyosho. When I was running V2's (i switched to velvets a while ago) I ran Durango springs on mine with good success.

My car doesn't have a lot of punch. I noticed I am running 30c batteries. How much would that matter? It seems most people are running 50c - 60c.

What does that motor timing do? I am running an LRP 8.5 xl.

Mine don't leak. If you're referring to the spacer between the o-rings, the V2 shocks come with a black spacer. Some folks have reported some stiction issues with these, I used the white spacers that come in the standard shock kit. Or you can sand the black ones down about half a mm to match the whites. The new red o-rings (included) are better than the old orange ones.. instead of oil, I generously covered the threads in green slime and they slid right through.

The only difficulty I had was getting the bleeder screw going in the cap. I discovered that if you use your 1/16 allen wrench and jam/tap it through the hole, it creates a much better pilot hole for the bleeder screw, while still being small enough to not allow any leaking.

Just wait and the big bores will come out