stephen5886

I think my HPI Nitro 3 RTR runs about 45, maybe even 50 with a the stock engine along with my two speed transmission and Kyosho tuned pipe. Does that sound correct? How fast does ur HPI go?

Rex2342

I'm going to be testing mine here in the next couple of days.I'm going to use the stop watch method and do several runs and just get an average.It may not be the most accurate method but at least it will get me in the ballpark.I'm running an Rs4 3 Type SS with a Fantom Fr15 and 23T/19T pinion combo and 39T/43T spur gears!!! It seems pretty fast but I guess we'll see.

WhiskyVR-4

short of the possibility of being underpowered, the engine used has little bearing on top speed. Top speed is purely a matter of knowing what your rpm is at rolling WOT, knowing your gear raios (spur/pinion and final drive) and knowing your tire diameters. Rolloout is a useful figure here. Add in a minor slip factor for the clutch, and you can calculate an ideal (theoretical) top speed rather easily. Yes, there are various drag issues to be accounted for, but it will give you a fairly good idea of what the car could be capable of on the top end. A more powerful engine (assume the same max rpm) will not net you more top speed, it will just get you there faster.

I have not yet tested mine, but I sincerely doubt my SS is moving anywhere near 50. It LOOKS fast, but I've seen 50mph and it LOOKS like 80mph

Gsir8

i wonder what seeing a car go 70 would look like

Aterlatus

A mess when it hits a wall

apocalapsi

I have a Rs4 3 Type SS with an O.S. .15 Cvrx engine. With the 45/41 spur gears and 19/23 pinion gears I was able to run 50mph as confirmed by GPS. Now , the handheld GPS was tie strapped to the car and ran this way and I am sure the added weight decreased top speed. As well, running the car without a body may have also limited top end. I was adamant at reaching 60+ mph so I changed the spur gears to a 39/43 and still ran the 19/23 pinion gears. In this configuration I ran 48.4 mph in first gear and a little faster in second. However, in second gear the engine was barely revving out in comparison to how high it was revving in first gear. This leads me to believe that i am overgeared and if it could rev out i'm sure it would break 60+mph. Any suggestions to get it to rev higher in second gear or is it plain impossible because it is too low of a gear?
The reason I ask is that I have noticed some fellows list a 37/41 spur gear combination and I think it would not rev out or is just overgeared. As well, with the pullstart, the 37/41 combo would have an axle distance of 29.5 and as such the pullstart would hit the rear diff gearbox housing preventing proper gear mesh. Any comments?? Suggestions for achieving a greater top speed would be greatly appreciated.

Mugen Mbx5

I have a rs4 2 with a two speed from a nitro mini,also a 15 cv I don't know what mph but this is the fastest car I have ever seen.The mini 2-speed is geared for the little rs4 mini tires, so it is a runner on the top end. It is quick also, don't think I lost bottom end just gained a TON of top speed.It is scary because if it hits something at top speed it will be junk....

nodolarsnosense

WHISKY
please explain more about hp, torque, rpm etc's effect on top speed

i always thought
more torque = the ability to turn with more strength ie not related to top speed but gets you there quicker as you said. its more important down low-med rather than up high in the rev range

hp or kw confuses me though, i thought hp is what govens top speed. ie if you gear 2 engines to give their highest speeds possible then the one with more hp will go faster.

that max freespinning engine rpm isnt the real variable, hp is the deciding factor but is positively related to an engines rpm at top speed
gear ratios and theoretical top rpm (for a freespinning engine)can be used to calculate general top speed but dont account for friction, but the actual top speed will depend on friction ie when the friction force (wind, bearing,gear mesh)opposing forward motion=forward thrust.so the cars top speed point will occur before the engine reaches its max (freespinning) rpm. the more hp the car has the closer to this max capable rpm it will be at top speed.so hp does determine top speed, and is related to rpm.

i know my statements may stand on thin ice and may be wrong so someone please explain more

id like to know how horsepower is measured(on paper not physically)

and if hp is directly proportional to max rpm or not, as there is a general relationship

drivercrazy23

My rs4 2 goes about 70, but I have a picco .21 in it so its a little over stock. I run a single speed tranny I dont know what the gearing it is though,

Rex2342

More torque means you can gear it for acceleration and it won't bogg down.Higher RPM means it will top out high witch means you can gear it taller and not damage the engine.HP really has nothing to do with anything.The torque and RPM is what you should look at when buying an engine because with the right gearing it will scream.

nodolarsnosense

hp has everything to do with car performance which is why it is talked about so much

its hard to get an engine with good torque and good hp. an engine usually has strength in either area.for offroad u usually look for high torque but this results in lower top speed ie less hp. where as onroad you look for high hp for higher top speed, with less emphasis on torque.rpm is just a side issue which relates to hp.

eg a world rally car only has about 300 hp but huge torque for down low because they need fast accel but they only need make about 200kmph max because of their tracks.
where as f1 cars hve 850+ hp and resonable yet relatively small torque, as they need reach high speeds ie 320kmph on straights and have high speed corners.as you can see hp and torque are what are important when it comes to speed and accel. true the f1 car will have higher rpm (i think about 18-19000) than a rally car but it isnt the important factor.

you cant gain speed or accel by gearing only loose it. ie at the engine output end (gear input) you have a set power to work with and at the other end of the gearing the car comes out utilizing all this power or with less power, not with more. the only way to increase the speed of a efficiently geared car is to boost hp, and the only way to increase accel of a efficiently geared car is to increase torque.

no car will be excellent at both accel and speed. either excellent at one, average at both. thats why you choose engines carefully for their role.but of couse a good engine may beat a bad engine at both.

drivercrazy23

My car is good at both, but Its also like putting a v10 in a neon or something. the picco .21 rated at 2.3 hp and like 37k rpm works great in the car, It will launch very hard off the line and will just keep accelerating till it hits top speed(65mph+). nodolarnosense, you are right on the torque and hp and gearing and all that, I agree 100% on what your saying.

Blackjaxx360

My Feedback: (2)

Hows this for a question for you guys. How is it that more horsepower will give you more top speed? It won't. Hp only tells you how fast you'll be getting to the top speed. More Rpms is what you want, along with hp and torque. A Fantom FR12 in place of that picco you mentioned with the exact same setup will give that car a higher top speed, and it has less hp! No matter how much hp you have, your motor will only spin as fast as it was designed for. Porting will help you gain some rpms, but not that much. Since 1:1 scale cars was brought into the discussion I'll use an example to support my argument. Look at the V-tec Honda engine. It has a red-line of 11,000 rpms. By using a higher rpm limit you allow some extra room for some extra horsepower. And if anyone has driven those cars knows they are fast, for a 4-banger. True HP and torque is important but remember rpms play a role, especially in RCs.

Militia

What are some good RPM ranges for high top speed.

Blackjaxx360

My Feedback: (2)

38,000 -----45,000 is great. Anymore than that you'll be losing your car.[&:]

Militia

Ok, well im looking at the Team Orion Wasp .18 w/slide valve. It has the rotary carb and valve carb specs combined. Im pretty sure the slide valve version will put out 37,000 RPM and the Rotary does 36,000 RPM. Would that be a good engine to buy?

nodolarsnosense

im reading my supercars book and look what it says

car, rpm, bhp, max speed
ferrari f40, 7000, 478, 201mph
lambo diablo vt, 7000, 492, 205mph
jaguar xj220, 7000, 542, 208mph
mclaren f1, 7000, 550, kick ass(i added that)

Aggdaddy

Guys all of these engine characteristics are important for determining car performance. We all have our opinions, however I would like to add my two cents to the bucket.

Torque is related to raw pulling power.
HP is related to top end speed.
RPM is also related to Top speed.

I haven't seen any torque ratings on 2 stroke r/c engines. So why are we even talking about that? HP is rated at the engines peak performance RPM, not necessarily at maximum RPM. At least that's how full size cars are rated. I don't know if our engines are rated that way. I'm looking at the specs of a .12TR turbo, and it says it is rated for 1.3bhp at 30k rpm. Practical rpm is between 4 and 38k. After 30k rpm its just over revving and may even be dropping in power. This seems like an engine suited for off road where power is needed midrange. Then you have the Trinity .12 SG rated at 1.8bhp at 39k rpm. Wow! Now that is a race engine. You have wide RPM range and .18 size power in a .12 engine.

BTW, I think that stock prelude would probably blow up at 11,000 rpms. 8000 would be the redline for a stock 2000 Honda prelude.

nodolarsnosense

i totally agree.
i always said rpm is relavent when talking about top speed but i am making the point hp is very important in relation to top speed because others say its unimportant and irrelevant.

ie a higher max rpm doesnt guaranty higher top speed because as Aggdady said you have a usable/practical rev range. where max hp matches the max practical rpm, for max power

Blackjaxx360

My Feedback: (2)

Never said a Prelude, unless it has the V-tec Engine in it. 11,000 Rpms is the redline for that engine.


You forgot to mention that F1 cars idle at 9000 Rpms!

Aterlatus

peugeot 406, 6500, 112, 125mph

Had to make my addition :P

CEN TR4, 37,000, 1.6, 50mph


Hmmmmm. If only I stuck an 1800cc nitro engine in my 406....................

nodolarsnosense

um try the mclaren f1 supercar, the production car, auguably the fastest production car ever
its also the best production car ever produced in the world in my oppinion
its a three seater
550hp, 7000rpm

not mclaren f1 formula one race car driven by Kimi. the single seater open wheeled car you always see on tv racing ferrari, williams etc
850+ hp, 18000+ rpm

the f1 supercar would destroy any production ferrari, lambo, porshe, bugatti, jag etc as an overall package.
maybe look it up on the net sometime, it does exist

Aggdaddy

My bad, the only high performance car I could think of was the prelude with a V-tec engine. Then there's the s2000. But neither of those have an 11,000rpm redline.

Rex2342

Spoon motorsports builds up engines for Honda's and they will spin 11,000 RPM.The B16a1 redlines at 8200.The S2000 and Prelude redline about the same but I can'y say for sure.My Neon redlines at 7500

Aggdaddy

I looked it up and I saw

prelude 2000 V-tec 7000rpm
s2000 9000rpm

Hey Rex do you have the SRT4 Neon?

Those engines made by SPoon, are those for like circuit racing or something?

If you guys haven't seen this already, The new Saleen Mustang S7 and the new Ferrari Enzo, beats that Mclaren f1 Supercar that goes for 850k. Top Speed and acceleration those two are the fastest production cars.

This information is in the Road and Track and Car and Driver mags that I glance at sometimes.