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Old 09-12-2006, 04:53 PM   #1
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Default HPI RS4-3 SS and CVR-X .18

Hello.

I was wondering if anyone knows how fast would a stock geared RS4 3 SS type go with an O.S. .18 CVR-X (pull start) engine? Has anyone clocked this on a speed trap before?

I am thinking of getting one of these but I am curious of the speed and durablility. What pipe would be good for this? Is this engine a direct bolt on or do I have to modify for it to fit? What motor mounts and flywheel? Would I need any drivetrain hop ups to handle the new power?

Any help would be very appreciated. I am currently running a O.S. .12 CVR-X on this car with the stock gears and pipe and it is probably hitting 40-45mph. Need more speed though


Thanks.
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Old 09-12-2006, 06:30 PM   #2
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well, on an extremely humid thick day in an overflow parking lot, i topped my rs4 out with the os 18 cv-rx (unmodified) at about 47mph with the highest gearing, but i wasnt running good fuel so i had my venom smart temp cut out at a certain point, im sure it would have got over 50mph, but i wasnt runnign my most aerodynamic body and i had a high downforce wing, now with it modified it woudl go at least 55mph in about 3 seconds, its a great engine
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Old 09-12-2006, 08:27 PM   #3
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So you are saying that this combination is capable of reaching a top speed of 60-70 mph with 20% good fuel? You mentioned 60mph in 3 seconds right?
I am impressed. I just want to know if my RS4 will keep up with the new
Traxxas 4-tec 3.3 engine that they claim hits 70 + mph. I need to know because I rather save to buy the new 4-tec from traxxas that already hits 70mph mark out of the box.

Does the O.S. provide good low end and top end speed? I think the rs4-3 is a great platform since it can probably handle the power because of the shaft drive. Do your tires rip out when jumping from a stand still?

I have so many questions because I would like to find out before dishing out a good $115 bucks for the O.S. plus the pipe.

Thanks for your help
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Old 09-12-2006, 09:29 PM   #4
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the rs4 with high gearing and the os 18 will probably reach 50-55mph average, its a good engine stock, but has serious power when modified, also it doesnt rev very high, you wont get the best top speed with this engine because it wont rev so high stock, my car might get lucky and hit over 55mph, but the os 18's just arent high revving engines, they are more about the torque, the reason mine revs higher is because of the extensive modding i have done to it, there is no way it will hit 70mph...thats 1/8 onroad racing speeds, and teh 3.3 4tech is a striaght line car, sure you can slap a 3.3 (.20) in it and gear it higher, but thats jsut too attract alot fo noobs, i think the 3.3 4tec will reach maybe 65mph, other than that, you run outta rom, plus top speed is generally useless, handlign is where the real issue is, the os 18 cv-rx is a great engine, starts easily, tunes just fine, and is mroe of a low end torque engine, it will get your rs4 up to speed quickly

edit: tires are something that is annoying to deal with, depending on how you drive, you will spend as much on tires as you do on fuel, my OS eats them up, i have tried every cmpound and tires, all the same, i have to say dont buy the venom magnetics tires too, so far my hpi 45 shores seem to have little wear on them, if you get rubber tires, just make sure to glue them down very well, and getting aluminum wheel hexes is a good idea, buy the ones from towerhobbies meant for the mt2, they are $13 cheaper and all you have to do is grind a little nub off, thats what i did and it works great

Last edited by apollo; 09-13-2006 at 05:58 AM.
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Old 09-13-2006, 06:31 AM   #5
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Thanks apollo. I don't know how to modify an engine so I was just thinking of buying it and dropping it right in. So it should do about 50mph right out of the box right?

Also, how about the .12 TZ from o.s.? Will this engine get me closer to 70 mph? I see it has about 1.5hp according to O.S.

Should I just save my pennies and get the TZ series in .12 or .18?

I would probably need to invest in a starter box as well since I don't think they come pull start.

What did you do to your O.S. .18CVR to make it faster? Is it difficult to do?

thx
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Old 09-13-2006, 09:32 AM   #6
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Quote:
Originally Posted by Speedbang
Should I just save my pennies and get the TZ series in .12 or .18?
thx
Most tracks have more races with .12 or .15 engines. To race a .18 you will have to wait until the open the less popular "outlaw" class

If you plan to race at a track go with .12
If you plan to parking lot bash with your friends go with the .18
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Old 09-13-2006, 02:27 PM   #7
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I forgot to mention that I just want this combination to bash on the street and parking lots but not to race officially.

I would like to have the fastest engine possible to fit the RS4 3 without much modification to the chassis and layout.

I would prefer pullstart convinience but I would not mind spending a little more on a starter box if it will be a big difference in speed.

I would like to be close to the 60-70mph range.

Is there a big difference in power, accelaration, and top speed if I get the O.S. CVR-X .18 as opposed to what I have now the O.S. .12 CVR-X?

Let me know your stories or experience. I like the price on the o.s. .18 CVR-X slide carb at my local hobby shop $110.00 brand new seems like a deal but I want to know a little more.

Thanks
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Old 09-13-2006, 02:56 PM   #8
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the OS from the box, broken in properly and geared high will get you to about 50mph...now thats pretty quick if you havent noticed, i jsut ran my rs4 again with the os 18 in it, i would say 50-55mph maximum but it is MOOOOOVING, you wont get an RS4 up to 70, top speed is useless, its fun, but it gets old, having the fastest car doesnt mean you are the best, i will take handling over sheer speed any day

the difference between the os 12 cv-r and the 18cv-r is that the 12 will have a higher rev range (not by much) but will lack low end torque, most people compensate by lowering the gearing, and the OS 18 like mine is a great engine, so simple to tune, started up 2nd pull the first time i even started it, and it was really rich, it will also start with almost any needle setting, ti started an entier turn rich for me a few weeks ago, idled fine, didnt wunna rev but it still ran

and a 12tz is for racing, useless for bashing, i know you are thinking "racing means fast" if you are just bashing with freinds, get a .18, the os 18tz is absolute overkill, prepare to replace the drivetrain if you do that, there is a such thing as overkill, and i have reached it with my RS4, its has soo much power that it tops out in 3 seconds if you can keep it straight, so thats 3 seconds of enjoyment, turn around, then another

and as for what i did to my os to modify it, learn to start, maintain, and tune an engine properly then i will explain everything to you

bottom line, bashing os 18 cv-rx, racing, os 12tz
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Old 09-13-2006, 04:48 PM   #9
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I think apollo is talking about stock 2 speed gearing with the 50 mph top end. If you gear for top end, you should be able to reach 60 mph without too much trouble but you will need a large parking lot to get there.
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Old 09-13-2006, 06:50 PM   #10
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rapid boy, i am talking about high gearing, for 1st i run 19/43 and for 2nd i run 23/39, thats the highest you can get and it spin the wheel like crazy, if you are lucky with an aerodynamic body, you will get to 55mph, but the engine isnt rated for over 32,000 rpm
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Old 09-13-2006, 07:49 PM   #11
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Thank apollo for making me understand. I know the difference between racing and bashing around with r/c and at this post am still a novice so I have not gotten into racing yet besides I have to tracks anywhere near where I live. I can handle the car pretty good and I know that speed is not everything to look for but it sure is fun

I think I will go for this engine because I know what you mean by overkilling an rs4. There is a limit for this car unless you want to spend hundreds of bucks upgrading drivetrain and suspension components.

So bottom line is that the O.S. CVR-X .18 is the simplest, reliable, and can keep up with other engines out there. I can say the same about my .12 cvr-x it has been a great engine but I need more bottom end (torque) to reach the higher speeds quicker. I have ran about 4 gallons of fuel through it and it is still quick at higher rpms.

So what gears should I put on my RS4 3 SS for the .18. It has the stock 2speed that came with the kit? And stock pinion gears as well.

Thanks Rapid Roy for the input
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Old 09-13-2006, 08:14 PM   #12
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http://www2.towerhobbies.com/cgi-bin...?&I=LXDHM2&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXDHM5&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXCLR7&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXM617&P=7

on the other hand, as soon as you feel willing to modifiy your engine, i will offer any help you need, i have someone sending me their almost new OS 18 cv-rx to modify, i seem to have a knack for modding engines

also get the racing clutch, it helps http://www2.towerhobbies.com/cgi-bin...?&I=LXLST3&P=7
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Old 09-14-2006, 07:48 PM   #13
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I am gonna order the stuff. I appreciate all you help. What break-in method did you use for this engine and how many tanks before letting it rip?

What is a safe running temp. for it after break in?

Just planning ahead of the fun
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Old 09-14-2006, 07:59 PM   #14
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for break in, use this, read post #6 http://www.rcuniverse.com/forum/m_2786285/tm.htm

and follow that methosd should be about 5-8 tanks before letting it run all out, but WOT bursts are acceptable and good in break in

and as for temp, during break in, i would say get it up to at least 220 degrees (F) after break in, it should run about 220-260, but it all depends on amount of airflow and fuel used, tune for performance
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Old 09-14-2006, 09:04 PM   #15
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I agree with you and this technique for break-in. Short bursts of WOT can is recommended. I will definitely not idle the engine. I will do small burst of WOT starting tank 2 and tank 1 will be short 1/2 throtle.

Thxs
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