Creating a TopSpeed car.

[xDennis]

Hello, I am current into drifting my TC4, however lately there has been a pretty large number of people in my area (Greensboro, NC) Getting into Speed runs, most of them run nitro.

I decided to pick up a 4 Tec with a 3.3 off ebay. I would like to know what steps I should take in upgrading the car to making it a serious contender in speed runs.

The car is factory with the exception of a 3.3 engine in it.

Do I start modding the engine? Do I buy a different engine and Mod it, do I start with electronics / tires?

Thanks everyone for any assistance:wave:

PS: this is my first nitro, so I'm learning as I go so any tuning tips is greatly appreciated as well.

[fasterthanspeed]

I am sorry but that is one of the worst engines for this application. First of all get a bigblock from rossi or nova rossi. Like the maranello.;):D ok, now youll need some motormounts. first design them how u would like them to be. If your good at building things u can probably make them urself. If not, youll need to go searching around.it wont be chespl. I think there is a gearing calculator at the last page of this forum.

[chicagonative17]

Basically you want a large clutch bell and small spur for high end. If you have the money, you can get that custom made too. For the motor, you want something with as high RPM as possible. You also want your tires to have a fairly large diameter, too large of a diameter will screw up your gearing.

You also want to have your 4tec PERFECTLY tuned. Stock, the 4tec can hit low 80s. Thats a fact because I have radared them with multiple radars after I tune them for customers at HobbyTownUSA. I have a 4Tec as well and you need to every once in a while make sure the carburator is nice and slippery. Sometimes with the 3.3 engine, small grit on the boot causes the needle to not open all the way. Get a good throttle servo, but not too heavy.

There is a lot more, but I scratched the surface for you enough to approach 100 mph.

Ian
HobbyTownUSA

[tcolesen]

If you want to go fast, electric is the best way to do it IMO. Electric power systems allow for much more driving time, since they don't require any work to get going. And, they aren't rated with any sort of peak horsepower or torque, and the powerband is limited to the output of the batteries. This is why most competition-type speed run attempts are with electrics (ajlovering is an exception :rolleyes: ).

[chicagonative17]

But then again, if you wanted MAX speed, you should have bought an electric car. Electric motors have a theoretical unlimited RPM. All you need to do is add more lipo battery power with a good brushless motor and airplane speed control to achieve 100-110 mph. the TC4 is a good base vehicle for this.

Ian
HobbyTownUSA

[xDennis]

Chicago,
Thanks for your input bruh. I currently Have a TC4, I was thinking about going with a mamba 5700 / 2c lipo for some speed runs.

However, I thought nitro would be fun also. I'll settle for 80's ;) I will do some more research and tuning and post as I go. I actually don't even have the car in yet, It will be in shortly I bought it off ebay for $205 bucks shipped..just something to have some fun with.

I don't see myself going all out like some of you guys do as once my classes start back up I'll have little time.

[Mod Man]

OK, I can agree with much of what was said, but not all.

First off, yes, the TC4 is a very good car for this application. The drivetrain will handle 4000 watts. However, the center driveshaft tends to resonate at high RPM. There are a few cures for this. The easiest is to sleeve the shaft. I can explain how to do that or do it for you at my shop.

Now, getting up to 100 is not as easy as "Just add horsepower." I did a huge amount of testing with my stock TC4 and found that I could not get beyond 92mph without alot of aerodynamic testing and insane horsepower.

My findings regarding this are, with a stock TC4 and a production body;

80mph can be achieved with 1000 watts

90mph requires 1700 to 1800 watts

100mph requires 2300 to 2500 watts

115mph requires 3200+ watts

It is easy to assume that more power gives an equal amount of speed. However, there is a huge added power requirement for a limited amount of added speed. Also, production bodies typically have an aerodynamic limit of about 90mph (depending on the body). So, it is very difficult to push them beyond that point.

There is a reason that the 100mph barrier has only been broken by a dozen or so people. It is possible, but very challenging. That is what makes it fun! :D

Matt

[1stGenCRXer]

Greensboro huh?

The petsmart parking lot isn't big enough for more than about 80mph with insane acceleration... if you want to be able to stop it in one piece that is.

[xDennis]

Matt,
When you speak about wattage are you speaking about the current from the battery or the current the motor has? I'm pretty ignorant when it comes to the more advanced tuning of electric.

1st GenCRXer,
Lol.. Do you frequent the Parking lots? I live on a road that is pretty str8, and long, the only limitation is probably radio and my eyesight.

[Mod Man]

I am talking about wattage drawn from the pack. My motors are (claimed by the manufacturer) 88 to 90% efficient. So, I can calculate the output power easily once I know the power draw.

Also, with a wedge body (GTP style body), higher speeds can be reached with similar power. However, both aerodynamics and power are required. Beyond that, at 100mph, the car will cover about 150 feet per second. So, lets say you have a car that runs an easy 80 mph, but seems to be still accellerating. If you need another 4 seconds to go from 80mph to 90mph, you will need an added 400 to 500 feet for that added 10mph.

I found this to be a huge issue with my TC4. At 70 ounces of weight, on 6S with my Vette body, I was able to hit 100 every run without a problem (the car consumed 2300 watts to do it). My current CF car weighs 93 ounces, pulls over 3800 watts, and had FAR superior aerodynamics, and has barely surpassed that. The issue I am currently fighting is accelleration in the distance I have to work with.

Now, back to the "Average" touring car; What draws people into this is taking a relatively stock car and adding a VSM (speed meter). They see something like 40mph. Cool! So, they gear up and see 43mph. Excellent, free speed! So, they pick up a faster motor. Wow, 51mph! Hmm, let's go brushless and 7 cells. Oh my goodness, 64mph! Alright, now it gets serious. So, they pull out all the stops and go lithium, pick up a better body, gear it way up, put on better tires, pick up an even better motor (like a Mamba Max), lower the suspension, etc, etc, etc. Now they have just added a cool $500 to their car and........... Oh, man 72mph. That stinks, you only gained 8 mph with all that added cash. Hmm, also the motor is getting really hot and the car tends to spin under accelleration. It is also getting hard to see and control. So, you start to do some aerodynamic testing and eek the car up to 80 (or close to it). But, you seem to have hit a limit on how fast you can go with the power you have.

Do you see the progression? As you build up more speed, the cost gets waayyy higher and it gets far more difficult to put the power down, get the tires to survive, make the car handle, learn to drive it that fast, and at that point, you are starting to have reliability problems with the car, maybe even burning out a motor or lipo pack.

I do not want to scare you away from top speed running. In fact, I want to see you persist in your own testing. There is something very cool about topping the next 10mph barrier. And, from my perspective, it is all worth it. Actually, with a small budget, this can be very fun because you are forced to try things that do not cost as much and, if you find something simple, you can share it with us and lower the cost of this hobby for everyone.

Little things can make a difference. I found that the $69 Eagle Tree Micrologger did more for my testing success than spending $330 on more lipos, looking for more speed. My $39 VSM (Venom Speed Meter) is a great tool for finding out if a change to the car made a positive, or negative affect. I found that eliminating most of rear wheel toe in helped. Running no rear wing gave me more speed, but took away some accelleration.

Keep testing and don't give up. Just be realistic about what to expect. ;)

Matt

[1stGenCRXer]

Matt,
1st GenCRXer,
Lol.. Do you frequent the Parking lots? I live on a road that is pretty str8, and long, the only limitation is probably radio and my eyesight.

I've been out there with those guys quite a few times when I went to HPU with my OS 18TZ powered CD3. My car at full windout is only good for around 80mph, and if I do get it wound out, I'm running out of room in a hurry. Good thing my car has good carbon brakes ;)

[chicagonative17]

A buddy of mine has a 1/10th scale electric touring car (I am killing myself for not remembering the make of it), this electric has a 2 speed transmission. He got it going 110 mph. So to compensate for loss of acceleration, you could consider finding or making a 2 speed transmission for an electric vehicle. With out this 2 speed transmission, his car didn't even top 100.

Ian
HobbyTownUSA

[Mod Man]

A buddy of mine has a 1/10th scale electric touring car (I am killing myself for not remembering the make of it), this electric has a 2 speed transmission. He got it going 110 mph. So to compensate for loss of acceleration, you could consider finding or making a 2 speed transmission for an electric vehicle. With out this 2 speed transmission, his car didn't even top 100.

Ian
HobbyTownUSA

I would like to know who that is. I am close to Chicago. Is he close by? Was a radar gun used, or what type of speed sensing? I prefer running my VSM and a radar gun combined to varify speed.

I would really like to know what he was running. 110 is EXTREMELY difficult to achieve. That is quite a feat, indeed.

A 2 speed is not a bad idea especially if you are low on power. The issue I have is getting enough traction with the power I have and the 1500 feet I have to work with. A two speed would do nothing in my situation. I have other solutions I am working on to solve it. What I do not want to do is rely on traction compound. I am trying to achieve the highest number possible with unprepped tires and an unprepped surface.

Matt

[chicagonative17]

Personal message is on the way.

Ian

[Mod Man]

Cool, thanks. ;)

Matt

[Mod Man]

Dennis,

If I were starting from scratch and wanted the best bang for the buck, I would run a TC4 or similar high quality 4wd touring car (unless a drag car suits you and you do not care about handling). Then I would pick up a Mamba Max system and run the highest safe voltage through it, maybe a 4600 on 4S would be a good start. Then I would get some cap tires or high quality foamies, gear the car tall and go for it. It is really not too terribly difficult to hit 80. 90 is tougher and 100 is very difficult. But, the setup I described whould be good for 80 to 85 depending on the body and how hard you intend to run the car.

Oh, your lipos should be high output lipos. I like Thunder Power Extreme cells.

Matt

[xDennis]

Matt, I see what you're saying, as you move up in speed class so will the budget have to lol. Now origionally I was going to use my TC4 for Drifting, or just having fun and the 4TEC for speed as I assumed (inccorectly) that nitro would be easier to make move fast. Now I'm thinking about selling the 4TEC and buying another TC4 carbon chassis or something and using that strictly for a speed car, is that the right idea? - TC4 , MambaMAx etc..

In regards to lipos, are the MaxAmps lipos "high output" ?
On towerhobbies, everyone talks about the 5700 with 3sell lipo, how does that compare to the 4600 w/ 4s?

[Mod Man]

Higher voltage is better for high horsepower. That is why I recommend them. 4600 is great on 4S.

You need to make sure your pack has a high "C" rating. I prefer Thunder Power Extreme 2200 cells. They have a 25C continuous, 50C three second "Burst" rating (how much they can put out for 3 second bursts). One 4S pack would cost about $115 and put out a reliable 110 amps. That is about 1300 watts of power. That should be good for 80 easily. I would also recommend a GTP body for the best aerodynamics possible.

Once you are at 80 mph, going faster requires about twice the money per 10mph of increase, assuming you have already done the best you can with aerodynamics, gearing and tires. So, if you have $350 in the power system for 80mph, $700 will be required to go 90 with the same car. 100 would require $1200 to $1400 in power system alone, typically. I am generalizing here. But, bear in mind, making speed gets progressively harder and harder with each increase.

Matt