mentallylost

Why is it that the X-Ray M18 is slaughtering the HPI Micro RS4 on the track? What is it about the design that sets it apart?

N.Smrt

I could sit here for hours comparing the two cars but lets not do that. Go to HPIRacing.com and then RCAmerica.com and compare the specs on the two cars. You will see there is no comparing. The HPI is a good design but an older one. I owned one when they first came out years ago. You've been to the track and from what I read you have seen the two cars battle. Actually, I like the way you put it, "Get slaughtered!" The HPI was the first 1/18 4WD but is now so dated, not to mention limited. It was freakin' awesome like 6 years ago. Even with the best conversion kit and unlimited budget on parts for the thing I would rather drive a bone stock M18. You can always tell who's got the RS4 because it can be seen bouncing and hopping its way through the corners. It is usually the only one of it's kind at the track and that should tell you something. The stock car has very little chassis space and forces you to mount components up high leading to roll-overs in the turns. It hops around or flips over, get it? Unlike the high-performance of Slovakian design. A few of us M18 drivers are planning on videotaping some of our cars on track racing. It will possibly be the most impressive footage anyone has ever captured of any R/C car on a carpet roadcourse. M18's have the potential to be the fastest of any class of cars scale-wise. For their size, with as much accelleration and g's these things are capable of, we believe 1/8 on-road gas cars may be now only second fastest. It's that sick. Look for the video. We're working on it. Go Team XRay!!

Rebal

All the weight is lower in the chassis and shaft drive making for less rotating mass would be my opinon on why the Xray is better

BIGTACO

iTrader: (10)

The overall quality of any Xray car is bar none one of the best, if not the best on the market. While building my M18 PRO I was absolutley taken aback at the fit and finish and just general material quality the car has. As far as the performance, well its is kick arse! I run my m18 at a huge track built for 1/10 and 1/8th scale cars. My setup is a bit extreme but this little bugger is able to keep up with most of the 1/10 scale nitros and electrics. I am holding our giant sweeper that terminates the 250 foot long straight at near 40 mph for god sakes! Not to mention the straight itself where I can track 55+ in a straight line without leaving the ground. Thats handling my friend...

Grizzbob

iTrader: (2)

Indeed, I & my local friends ran the HPI car for some time before the M18 came out, & when it hit, we were all amazed at how much better it handled on most surfaces. And I think its independent suspension definitely has a lot to do with it.....

RaceAce701

iTrader: (87)

M18 all the way

I just picked one up and even in stock form it rocks

ther is surprisingly alot of room for even standard small electronics

duneland

The mrs4 design is all about compromise. Front suspension weight is carried by the upper arms which are a-symetrical. rear end is, well, silly... I decided I don't have the time or motivation to continue....

mentallylost

I'm not asking whether or not I need to buy one over the other. The answer to that would be the M18 hands down if I were planning to race in a semi-stock form. But I am not asking the differences for that reason. Nor is this a "belt vs. shaft" discussion. That’s been argued too many times in other threads.

What's got me thinking is what could be accomplished if someone was to attempt to overhaul a MRS4 into a performance configuration. What if a person was to fabricate an actual pan chassis with a rear "T" bar suspension, dual sided VCS shocks, and a floating motor pod?

I understand that the M18 has unparalleled fit and finish in comparison. And I believe that having the majority of the weight on the lower chassis does a lot to help. But what about independent rear suspensions as opposed to the solid rear axel? Do the people with the Scalpels feel that they will in the end have the faster lap times at the track? Or again would the independent rear suspension of the M18 help them as well? That’s why I am asking the differences.

You don’t need to continue if you don’t want to, but what is wrong with the upper front arms being asymmetrical? Would crossing the front shocks correct this?

What it all comes down to is that I like to fiddle with things. I don’t like to sit around and watch TV. I have a billion hobbies, and creating things is just one of them. I bought a MRS4 rolling chassis off of member on another forum with the intention of fabricating a pan chassis of my own design. If it works out, then great. If it doesn’t work the way that I am hoping for, then oh well. I won’t be out more than just a bit of time that I would have spent messing with something else.

I probably should have been more specific in my original post as to my intentions. But this is the reason that I asked. So now, can anyone think of the things that they would put into a chassis design for a belt driven 1/18th scale 4 wheel drive car that would use primarily MRS4 parts?

velcro

If the belt was down the center of the car, then there would be a few suggestions, with the rs4 the way it sits I would suggest selling it to a museum. It is really a hopeless pile, like everyone has suggested, buy the x-ray, you cannot polish a terd!!

Grizzbob

iTrader: (2)

Except on VERY smooth, clean surfaces(like carpet), that floating pod-style suspension just won';t work well, simply can't react fast enough to handle less than perfect surfaces(which is the same as for T-plate pan cars, they just don't do as well on those surfaces, they were really meant for carpet only). I think if someone wanted to make that design work better on non-carpet tracks, they'd need to come up with a rear design much like CRC's pan cars(no T-plate, but instead 3 dampening tubes & 3 springs to handle movement in all directions), but even at that it still wouldn't be quite as effective as a fully independent suspension, IMO. Sometimes, you just need all 4 suspension arms to move on their own to stay hooked up.....

mentallylost

lol

Thanks for the help GrizzBob. I'll take a closed look at the CRC cars. It will be intended to ran on carpet.

oXYnary

iTrader: (4)

The closest chassis still in production that is like you want to create is the Griffin.

http://www.dragonracingproducts.com/sect1_chassis.htm

duneland

Suspension components that carry the weight of the chassis, should be the same (left to right). The mrs4 arms, being different, will react differently when loaded/unloaded. I believe this contributes to the cars unpredictabillity.
This is just one of the cars overall shortcommings. Most(if not all) of the things, you suggested, have been tried. You can certainly improve the car a lot, with the things you want to try. It would be more of a challenge to make the car worse, than to make it better. If your goals are realistic, you can make the car competetive at some level.

Bermbuster

iTrader: (11)

I have been racing micro 18th for two years and when we first started my son and I ran the mrs4s. After a few races we changed and got m18s...
The mrs4 is not as durable as the m18. We would bend axles and break front knuckles. If you really want to try running them I will sell you ours cheap Mentally Lost just PM me....

Rebal

It would be killer if HPI saw this kind of stuff, listened and did something. I look forward to the day when there are multiple companys manufacturing 4wd 18ths onroad. I think its coming cause the world is getting smaller