DIY Electric Car Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
I am starting to amass information to build a trike. A big trike, a Harley
Trike. I have discussed a motor with Jim H. He thinks a 6 inch motor will
do. I have found a differential from a BMW Z3 with 4:44 gearing. I next have
to calculate tire diameter and then I want to assume a 70mph top speed.

Finally the question. Jim, all, What is the top safe RPM of said 6 inch
motor? What top speed of any other recommended motor. Please note this is
not a race bike, I got all the speed I needed from the 928 I have for sale.
I am building this to be a commuter vehicle.

Another question. How much voltage will I need for the top speed or do I
need to ask that question once I find out what my top speed RPM will be?




Mark


----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Saturday, August 18, 2007 10:33 AM
Subject: EV Digest, Vol 1, Issue 48


> This message has been processed by Symantec's AntiVirus Technology.
>
> Unknown00000000.data was not scanned for viruses because too many nested
> levels of files were found.
>
>
> For more information on antivirus tips and technology, visit
> http://ses.symantec.com/

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

·
Registered
Joined
·
70 Posts
Discussion Starter #3
It really depends on the motor. Anything from about 2,000 rpm to 12,000
rpm is possible. Most likely it will be in the 3,500 to 6,000 RPM range.

Pick a motor and you'll know the speed.

> I am starting to amass information to build a trike. A big trike, a Harley
> Trike. I have discussed a motor with Jim H. He thinks a 6 inch motor will
> do. I have found a differential from a BMW Z3 with 4:44 gearing. I next
> have
> to calculate tire diameter and then I want to assume a 70mph top speed.
>
> Finally the question. Jim, all, What is the top safe RPM of said 6 inch
> motor? What top speed of any other recommended motor. Please note this is
> not a race bike, I got all the speed I needed from the 928 I have for
> sale.
> I am building this to be a commuter vehicle.
>
> Another question. How much voltage will I need for the top speed or do I
> need to ask that question once I find out what my top speed RPM will be?
>
>
>
>
> Mark
>
>
> ----- Original Message -----
> From: <[email protected]>
> To: <[email protected]>
> Sent: Saturday, August 18, 2007 10:33 AM
> Subject: EV Digest, Vol 1, Issue 48
>
>
>> This message has been processed by Symantec's AntiVirus Technology.
>>
>> Unknown00000000.data was not scanned for viruses because too many nested
>> levels of files were found.
>>
>>
>> For more information on antivirus tips and technology, visit
>> http://ses.symantec.com/
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


--
If you send email to me, or the EVDL, that has > 4 lines of legalistic
junk at the end; then you are specifically authorizing me to do whatever I
wish with the message. By posting the message you agree that your long
legalistic signature is void.

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

·
Registered
Joined
·
70 Posts
Discussion Starter #4
I have a prestolite mtc-4001, in a 1974 VW beetle, with afaik a standard transmission. I don't want to overspeed my motor, and don't have a rpm gauge in my car. Without buying one a rpm guage, how can I tell what speed the motor is running at. I know the size of my tires (or will when I go home and measure) and can look up the transmission ratios. The problem is I don't understand the ratios, to know how to convert the speedometer back to rpm at the motor. Does anyone understand my question and dilema? And if you do, can you help me out?

Thanks,
Brian


On Sat Aug 18 23:37 , Peter VanDerWal <[email protected]> sent:

>It really depends on the motor. Anything from about 2,000 rpm to 12,000
>rpm is possible. Most likely it will be in the 3,500 to 6,000 RPM range.
>
>Pick a motor and you'll know the speed.


---- Msg sent via @=WebMail - http://webmail.usu.edu/

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 

·
Registered
Joined
·
70 Posts
Discussion Starter #5
You can monitor the rpm of the motor is at by reference it to the mph
speedometer.

Find out what the each gear ratio is at each speed in the transmission and
the rear axle ratio.

Then using this formula:

RPM x WC (Wheel Circumference)
MPH = --------------
RATIO x 1056

The ratio is the overall ratio by multiplying the transmission gear ratio
times the axle ratio.

To find the wheel circumference, it is best to put a mark on the tire and
one on the floor and rotate it one turn it until the mark is on the floor
again and than measure between the reference marks.


For RPM, the formula is converted to:

MPH x RATIO x 1056
RPM = --------------------
WC

Solve each RPM for each gear ratio in 1st, 2nd, 3rd, 4th, etc.

In my EV, I know that if I drive in 1st gear to about 25 mph, then motor is
at 6000 rpm, in 2nd gear it about 45 mph at 6000 rpm and in 3rd gear its 92
mph at 6000 rpm.

You can get a digital counter from www.surplussales.com which can count the
number of turns a shaft turns. There is a switch yuu can select from
counter to rpm. All you need is one magnet on the rotating shaft. I have a
1/4 inch diameter neomagnet embedded into a steel coupler which is glue in
with JB Weld.

These are a very small unit, which is about 1 inch wide by 3 inches long
which cost me about $20.00. Use it mostly bench testing.

Roland





----- Original Message -----
From: <[email protected]>
To: <[email protected]>; "Electric Vehicle Discussion List"
<[email protected]>
Sent: Monday, August 20, 2007 7:47 AM
Subject: Re: [EVDL] Top speed RPM question.


> I have a prestolite mtc-4001, in a 1974 VW beetle, with afaik a standard
> transmission. I don't want to overspeed my motor, and don't have a rpm
> gauge in my car. Without buying one a rpm guage, how can I tell what
> speed the motor is running at. I know the size of my tires (or will when
> I go home and measure) and can look up the transmission ratios. The
> problem is I don't understand the ratios, to know how to convert the
> speedometer back to rpm at the motor. Does anyone understand my question
> and dilema? And if you do, can you help me out?
>
> Thanks,
> Brian
>
>
> On Sat Aug 18 23:37 , Peter VanDerWal <[email protected]> sent:
>
> >It really depends on the motor. Anything from about 2,000 rpm to 12,000
> >rpm is possible. Most likely it will be in the 3,500 to 6,000 RPM range.
> >
> >Pick a motor and you'll know the speed.
>
>
> ---- Msg sent via @=WebMail - http://webmail.usu.edu/
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
 
1 - 7 of 7 Posts
Top