.21 conversion HPI RS4 2

[kwong2001]

I'll see about getting a video made today. Gotta see what my friend is up to.

 

[Carbon_Savage418]

yay!!! hope everything goes well, with the car...

 

[kwong2001]

After running 1-1/2 tanks through the engine on the dry surface, i've managed to almost completely burn up the tread on the rear tires, the fronts have about 25% left. From a stand still, it'll spin all four tires with ease, but there's TONS of wheel hop which makes it hard to control. I've managed to flip it twice on a hard launch when it started to spin out of control.

The 2-speed is completely worthless, I can either get it to not shift, or shift too soon. I might just set the car to shift immediately into second gear since i've found the car easier to do speed runs once it's in 2nd gear.

Overall, i'm surprised the car is holding up as well as it is. More people need to do a .21 conversion lol, why bother with small blocks?

Oh, and just so you guys know, the handling isn't terribly bad, it's just the overpowered engine that makes things difficult.

 

[Lessen]

Oh, and just so you guys know, the handling isn't terribly bad, it's just the overpowered engine that makes things difficult.

so it's like a 1/10 scale Nextel Cup car. just gotta practive your trigger finger work.

 

[kwong2001]

Well the car is officially out of commision. After my first real test drive, the diffs loosened up a TON. I tried tightening them down real good, but ended up breaking off the adjusting screw. Been to the hobby shop twice today, and i'm not going back for a third time. Maybe it'll get running next week.

Edit: i've decided i'll do a spool front and rear conversion for simplicity. Gonna use the stage-d solid axle conversion, i'm pretty sure it will work with an RS4 2 even though officially, it only works on an RS4 3. Since I need to get a new diff house, i'll get the 32T diff pulley which will give me a little better gearing.

Gotta look to see what size clutchbell and spur gear I have, but i'll be buying a 37/20 combination. According to my calculations, this will give me a solid 67mph @ 30,000rpm.

I'll probably buy all the stuff sometime next week. I wanna take a break from spending money on the car.

 

[AC48]

I wanna take a break from spending money on the car.

Liar.

lol, looks like its holding up somewhat. I'm surprised it even took one hole tank lol. I still need to see this thing going 67 tho.

 

[kwong2001]

lol, well i''m at least trying to cut back on the spending. I think the solid diffs will get the drivetrain nearly bulletproof, probably only thing left to break is the belts and spur gears. Great, I just jinxed myself

Oh, btw, I did order the axles and new primary gears...only costed $60 from RushRC Should be here next week.

 

[AC48]

Spunds good kwong, but I'm afraid the 67mph is a little weak, you should be going at least 80mph

 

[kwong2001]

Well I assembled the diffs, but unfortunately, ran into a SERIOUS problem. They fit fine, but I didn't think about the belts. Haven't checked the front, but the back definitely doesn't fit. Tried moving the middle belt to the rear since it's 6 teeth less, but it's too small. So I either gotta find the right sized belts, or find some larger pulleys

 

[.21Rc10GT]

As soon as you lock the diffs, get ready to bust some cvds. This looks like an awesome project. Good luck with it! And get a vid up soon!

 

[kwong2001]

When to the hobby shop to find some pulley's or belts, but it was pretty much unsuccessful. I found a smaller belt that might work for the front, and bought a mystery duratrash one, but dunno if any of it will fit.

Contacted wolf pack radicals to see if they have a 25T pulley that would work. I'll probably have to go custom on the pulley...but on the bright side, it'll get my gearing to right around 80mph at peak horsepower.

 

[Diver6127]

Hey Kwong, I may have some slicks left over from my fusion. I never used em since I ran foams. They were never glued and don't have the inserts. You want em if I can find em? They're 24mm, that's why I never used em.

 

[kwong2001]

If you could find them, that'd be awesome Diver, i'll take all the tires I can get

 

[kwong2001]

Just a small update:

I've been corresponding with Wolfgang from Wolf Pack Radicals and he's been quite helpful. Unfortunately, it looks like the 25T pulley conversion is gonna be a lot of work. If anyone knows about the 100mph Super Nitro Steve Pond of RCCA built, he ran into a lot of the same problems i'll be running into. The chassis and engine block both need to be machined to get the necessary clearance for the larger diameter pulley. Wolfgang has offered to do the machining for me, but I might end up just taking the dremel and doing it myself. I'm kind of a DIYer.

Anyhoo, car is still out of commission, and it's very much in pieces. I'm gonna goto the hobby shop tomorrow and buy the stock 39T diff pulley's so I can at least drive the car. Hopefully within a month i'll be able to get the new gears made.

It looks like the final drive ratio will be 2.37 with the 32/25 drivetrain ratio, and 37/20 primary ratio. Wolfgang has mentioned a 23T clutchbell, which would put the final drive at 2.06, but I don't know if there's a 23T that would fit, nor do I know if that gearing would be too much for the engine/car to handle.

 

[AC48]

Any updates Kwong? Gotta get this thing going and get a vid of it! lol

Good luck with it.

 

[kwong2001]

Still outta commision, gotta order some 25T pulleys I actually put the car away.

 

[kwong2001]

Small update, i'm leaving it with basically a stock drivetrain, should be good for about 70mph (calculated). Bought some foam tires, and i'm gonna try to order a better header.

My mom bought a new computer and she can do video editing and transfer video from a camcorder to the computer. So once the header comes in, and when the weather is good, i'll finally make a video.

 

[Lessen]

finally. lol cool man.