B&B electric Cobra

ZOERA-SC7XX · #1 (**permalink**) 11-17-2011, 06:40 PM

It's all in the gearing. Electric motors are not like internal combustion engines. Apples and oranges.

AL427SBF · #2 (**permalink**) 11-17-2011, 07:41 PM

Quote:

Originally Posted by ZOERA-SC7XX

It's all in the gearing. Electric motors are not like internal combustion engines. Apples and oranges.

fyi, electric motor power translates directly to hp. 10kw = 13.4 hp, the only difference is you have instant torque.

do the math, you need OVER 1200 hp of "juice" (= 895kw+) to do 276, more power than the bugatti veyron. the fastest electric car on record went 208 and is about as aerodynamic as they come.

B&B's car probably tops out at 136, that 10k redline is probably the motor rating under "no load".

lnfletcher · #3 (**permalink**) 11-18-2011, 12:41 PM

Quote:

Originally Posted by AL427SBF

sumpin' ain't addin' up ...

"i have hit a top speed of 138 and this was in third gear"
"the motor has a red line of 10k and i was at about 5k at 138"

... so you are geared for 276 at redline in 3rd gear

Quote:

Originally Posted by ZOERA-SC7XX

It's all in the gearing. Electric motors are not like internal combustion engines. Apples and oranges.

RPM is RPM whether gas or electric.
He is running a Tremec TKO 600 so the 3rd gear ratio is 1.28:1
That would mean he has to have 2.30 rear end gears to make 138 at 5K!
I noticed on the burnouts that it is an open rear end. (One stripe)

I'm still interested in the cost of the electric over the gas. Looks like it's gonna cost about 25K min for the motor batteries and controller!

Bryan Anderson · #4 (**permalink**) 11-20-2011, 10:34 AM

we have been playing around with the rear ratio we started with a 2.75 we are now playing with a 3.80 yes they are open gear, could not get the limited slip to work with the electric drive train, the clutch's would not lock up, so we have gone back to the open and it works great. as for cost on the battery set-up this car is way up their 48,000 for everything this will drop once I get the weight of the car down a little more so we can back off on the batteries, this car is what the customer wanted so it has 138 cells in it, with the weight drop the battery cost will go down.