4.5 / 5.5 / 6.5 characteristics.

andys · #1 17-01-2010

Something i've being wondering...

Is it that case that theoretically, the top speed of say a 4.5 / 5.5 / 6.5 is that same if geared correctly in the same car / setup ?

Is it simply a case of how the power is delivered that differentiates the different motors now a-days, or is there more to it than that ?

Reason I ask is I favor a 4.5, always end up going back to it as it feels more punchy, but indoors on a slippy floor it's a real handful. Would I go just as quick (down the straight) with a 6.5 geared higher ??

Cheers.

markwilliamson2001 · #2 17-01-2010

4.5 is more powerful than a 6.5 both in torque and top speed.
The main differences come, when using different sized rotors, or thinner wire in the stators...E.g. Novak 'L' Light range or Nosram/LRP 12.5mm rotors.

I would be looking at maximum 6.5 indoors on polished floor in a 4wd! Should be more than enough, maybe even a 7.5! If geared correctly, the motor should be warm to hot to touch, but not REALLY HOT. You should be able to hold your finger on it for a bit. Might be worth investing in a temp probe to check against the manufacturer instructions. Sintered rotors also help the motor run cooler as well, so look out for these. I ran a 8.5 in a B4 on carpet on Friday, and it was more than enough IMO.

HTH

markwilliamson2001 · #3 17-01-2010

In reference to your 6.5 statement, yes, as it would be spinning the wheels far less. You would be able to get on the power much more easily. Maybe even try that 7.5!

andys · #4 17-01-2010

Cheers for the reply.

What i'm getting at is :

If the car is geared correctly (optimally) with say a 6.5, would it's top speed be the same as exactly the same car geared again properly - (lower obviously) with a 4.5 ?

Last time I tried a 6.5 in my 4wd it felt slow......

I want to keep the top speed, but loose some of the punch that the 4.5 generates. I already have the speedo at it's lowest punch setting and the throttle curve set on the tranny !

Cheers.

mole2k · #5 17-01-2010

If it feels slow then it should be easier to drive giving you more consistant lap times. I would be looking at the overall laptimes over 5 min and deciding what to run from there.

Big G · #6 17-01-2010

I ran a 5.5. in my b44 since going brushless and without brand new tyres found the car challenging to drive on polished floor. I was still reasonably competitive, but after a couple of weeks my tyres lost their grip noticeabley..

Then my speedo went faulty so I popped a GTX/16x3 into the car. I found it so easy to drive being slower. I could corner an inch from the markers and my consistency was perfect with only a second between my fastest and slowest lap. Yes the car wasn't the fastest down the straight, but the straight is only 10 metres long. Made up all my time on the corners being able to get on the power quicker than anyone else without any risk of the car under or oversteering.

I now have the 5.5 back in and it's so much of a handful to drive. It's not very relaxed to drive having to concentrate a lot more. I backed off my timing on the motor and speedo to the lowest and reduced the punch to about level 3 (SP LPF), but it was still tricky to be consistent. I then adjusted my throttle high point to 70% and the car became very docile to drive, but it was calm and easy. My times improved a lot.

This isn't the best way as the motor doesn't have any soul like before and I do have a 7.5 on order. It does get fairly warm by doing this also.

Just my 2p on the subject.

andys · #7 17-01-2010

Cheers for the reply G.

It's always going to be the case that the slower car is going to be easier to drive, it's a balance between speed / power and ability to get it around the track consistently

What i'm wondering is if the potential is there to go physically 'as-fast' with the slower motor ? I think i'll go for the 6.5 again and see how I get on.

What's the most popular wind used in 4wd off-road anyway ??

samd · #8 17-01-2010

Dont forget to have fun as well andy! Your car always looks better with a 4,5 in it anyway!
I have a 5.5 in mine and i think its a nice balance of driveability and fun, i used to run a sensorless tekin 537, about 7.5 power, i was smoother but it wasnt as much fun so i ditched it

andys · #9 17-01-2010

Quote:

Originally Posted by samd

Dont forget to have fun as well andy! Your car always looks better with a 4,5 in it anyway!
I have a 5.5 in mine and i think its a nice balance of driveability and fun, i used to run a sensorless tekin 537, about 7.5 power, i was smoother but it wasnt as much fun so i ditched it

Amen to that Sam !

Thing is I ran the B-Max last night at York, with the 4.5

and I struggled accelerating on the slippy floor, car just wanted to spin, and it did if I wasn't careful.

I want to go as fast, but without all the low down power, so i'm just trying to understand if I can do that with say a 6.5 as that's all I have apart from the 4.5.

Might need to get a 5.5, but which one ???

P.S See you at Bury next week ?

Big G · #10 17-01-2010

I have speed passion v3 motors are they are very good. the plugs make removing and swapping motors very easy without the need to solder.

Gayo · #11 17-01-2010

Your 6.5 should'nt feel slow. I would guess that you are undergeared on the 6.5. When I switched to BL 3 years ago, the 6.5 I had on my 2wd felt really flat, with 19 turns-like top speed.

I was about to sell it until I tried 3 teeth up (!), then it really came to life

samd · #12 17-01-2010

Not going to make bury andy, worksop for me next. Ive tried most motors, novak, novak lights, speed passion, lrp x12 and i have gone back to novaks and am very happy. Fast, smooth, cool running, and thats the older 5.5R version, the newer ones are ment to be even better.

andys · #13 17-01-2010

Sam.

Is that the nice looking orange and black ones ? Expensive though aren't they... my X11's are mainly 2nd hand off oople or e-bay !

Timee80 · #14 17-01-2010

yes they are indeed the orange and black ones, and they are great motors. the 7.5t felt perfect indoors in my b44 and runs quite cool

samd · #15 17-01-2010

Mines the older silver and purple ring R one, i got it of a guy on here for 30 quid, it does the job very well.

Richard Lowe · #16 18-01-2010

With the right lipo a 6.5 is plenty fast enough now in 4wd Andy

mikeyscott · #17 18-01-2010

At Petit I wish I'd run a milder motors

7.5 in 2WD wish I'd gone 8.5 or even 9.5
6.5 in 4WD normally run 7.5

rob m · #18 18-01-2010

Quote:

Originally Posted by andys

Cheers for the reply.

I want to keep the top speed, but loose some of the punch that the 4.5 generates. I already have the speedo at it's lowest punch setting and the throttle curve set on the tranny !

Cheers.

ive noticed this on motors of the same turns,i have a losi 6.5t and a novak v 6.5t,tried them in my b4.the novak is far more agressive on throttle,and made it hard work to drive but top speed was about the same,so im thinking could i gear the novak a lot higher to give me less punch but more top speed due to it having far more torque without it overheating,,i have a losi 4.5t in my b44 that seems good on punch and top speed so happy with that

andys · #19 20-01-2010

I've decided to try the 6.5 again instead of a 4.5 in my BMax.

If I was running a 16t pinion on the 4.5, what should I run on the 6.5 ? 20t ?

Cheers.

Big G · #20 20-01-2010

My 7.5 arrived yesterday so I popped it into the B44 for our return to indoor racing at ludlow and the car was great. it felt really nice all night and I had intended to try different settings, but it just felt so good right from the off. Can't sing the 7.5's praises enough! And I got to experience swapping 2 SP v3 motors. muhahaa at the plugs

I started on a 19T pinion. Up 2 teeth from my 17T I run on the 5.5 and it ran ok, but was very hot to touch after practice so I took it down to a 18T and turned the timing up 1 level. I think to 5. Car felt the same to drive. Slightly more bottom end as expected, but not noticeably slower top end and it was a lot cooler after a race.