FWD Powerhouse of a CA

[DjLiquid]

I had a question proposed to me. Im aiming to shoot out about 300+hp at the wheels and that would probably be equivelant to close to 400 at the flywheel. I had asked to me what im going to do about re enforcing the diff. He had mentioned that with the power im aiming for the diff pins on the transmission would just blow out like they do in the 96-00 Caravans. Anyone had any problems with their transmissions?

[pulsar gtr]

The CA18de FWD transmission will take this hp without any problems, the dam dodge carvans, they have a bad rep when it comes to trannys, at my brothers shOp he replaces them all the time, I have seen the carvans have bad trannies as low as 65K Km You Don't need to worry about the transmission, I am running similar HP for years now and I never had a problem.

RafiPULSAR GTR

[float_6969]

I don't have much experience with the FWD CA transmission, but Nissan usually overbuilds their trannys, so I don't think you've got much to worry about in that department. I do need to comment on something though. If you were loosing 100hp through drivetrain losses, your fluids would boil and anything aluminum would turn to liquid. Drivetrain losses aren't NEARLY as much as people think they are....

[redamnavit]

Using the 20% figure that seems popular you'd be at 375hp at the crank. I usually see FWD cars rated at 15-18% drivetrain loss, which puts you between 345-354hp. Whatever, it'll be quite fast.

[float_6969]

I honestly still think that 20% is pretty high. Here's a little math off the top of my head...engine makes 400 horsepower and you get 300 of that to the ground. That means that you are loosing 100hp to "drivetrain losses". Each horsepower is about 3/4 of a Kilowatt. So 100 hp is approx 75 Kilowatts. Now lets say we run the motor, at that figure, for one hour. We now have released 75KW-Hour's of energy. That is the equivilent of approx. 64,500,000 calories of energy. Now if we take a transmission and over-figure, and say that it has 100lbs of aluminum in it (if it was less, this would be even worse) we can convert 100lbs of aluminum to approx 45,300grams of aluminum. The specif heat,defined as (cal/g oC) of Aluminum is 0.215. That number basically tells us how much energy has to be put into 1gram of aluminum to get it to change one degree Celcius. So using the numbers we've come up with so far, the Aluminum's temperature would raise approx 1,400 degrees celcius. The melting point of Aluminum is about 660 degrees celcius. Granted that we would have to run the engine for one hour for this to happen. But even at half and hour, the temperature will raise 700degrees. And to be honest, i've rounded all of these numbers down, so they are all actually lower than what they would be. Just something to think about...

[float_6969]

Here's a little more info on the subject that I just found...

http://www.sdsefi.com/techdyno.htm

[mikeh16]

I honestly still think that 20% is pretty high. Here's a little math off the top of my head...engine makes 400 horsepower and you get 300 of that to the ground. That means that you are loosing 100hp to "drivetrain losses". Each horsepower is about 3/4 of a Kilowatt. So 100 hp is approx 75 Kilowatts. Now lets say we run the motor, at that figure, for one hour. We now have released 75KW-Hour's of energy. That is the equivilent of approx. 64,500,000 calories of energy. Now if we take a transmission and over-figure, and say that it has 100lbs of aluminum in it (if it was less, this would be even worse) we can convert 100lbs of aluminum to approx 45,300grams of aluminum. The specif heat,defined as (cal/g oC) of Aluminum is 0.215. That number basically tells us how much energy has to be put into 1gram of aluminum to get it to change one degree Celcius. So using the numbers we've come up with so far, the Aluminum's temperature would raise approx 1,400 degrees celcius. The melting point of Aluminum is about 660 degrees celcius. Granted that we would have to run the engine for one hour for this to happen. But even at half and hour, the temperature will raise 700degrees. And to be honest, i've rounded all of these numbers down, so they are all actually lower than what they would be. Just something to think about...

Ummmmmmm.......wow. Thats thinking!

[iliketocrash]

and on top of that wouldn't you have to take into account the transmission fluid and heat dissapation as well? i'm sure everything would still burn up or melt in the end but i figured i'd just throw that in. =P

[DjLiquid]

I wasnt really sure of how much HP I want to run, that's why I said 300+ but youre taking it as 300.. I should have made myself a little more clearer, my mistake

[float_6969]

and on top of that wouldn't you have to take into account the transmission fluid and heat dissapation as well? i'm sure everything would still burn up or melt in the end but i figured i'd just throw that in. =P

Yes, but that was enough thinking, in and of itself. I'm sure my numbers are off some, but they aren't so far off the end result wouldn't be the same.

And just to clarify, in actuality, in our cars (and just about any FR layout), they drivetrain losses are really only about 10-13%, most of which is in the differential. A FF layout has considerably less and actually gets more of it's power to the wheels than a FR layout does.

[redamnavit]

The majority of drivetrain loss is through the force required to spin the transmission gears + driveshaft + diff + axles + wheels though, correct? Kinetic dissipation instead of heat. Otherwise I'd burn my hand when I went to shift.

I'm not saying you're wrong; 20% is likely over-conservative. I suppose you'd have to remove the engine and put some sort of torque-wrench like device attached to the transmission input shaft to determine exactly how much energy is required (in a given gear) to get the wheels to move.

[nocwage]

DOn't forget, those calculations are on the idea you're MAKING 300hp FOR AN HOUR.I.e. Full throttle... FOR AN HOUR..99% of your driving will require only ~50hp Just like how my crappy V6 altima could cruise at almost 0 throttle.

[float_6969]

Read that link I posted, it explained it better than I did.

[boost_boy]

I had a question proposed to me. Im aiming to shoot out about 300+hp at the wheels and that would probably be equivelant to close to 400 at the flywheel. I had asked to me what im going to do about re enforcing the diff. He had mentioned that with the power im aiming for the diff pins on the transmission would just blow out like they do in the 96-00 Caravans. Anyone had any problems with their transmissions?

I've never had such problems with diff pins and things of that nature. The CA18's FWD trannies are pretty strong and should support your 300hp quest. Here's an old dyno with an internally stock CA with a slightly modified CA18 transmission: This was done at 20psi of boost on a T3/T04E stage III with a .48 backhousing.

This was done on a CA18DET with the addition of HKS 264 camshafts, T3/T04E stage III with a .48 backhousing and about 13-15psi of boost (I forget) ab\

Here's a pic of the engine bay of my G/F's 1990 B12 Nissan sentra:

So it goes to show that anything is possible if you put your mind and money together along with entrusting in nissan engineering.

Dee