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how do you find engine max speed & max rpm
ian.lucas - 23/5/08 at 07:29 PM

I'm just filling in my form for my sva test & 1 of the questions asks what is the max speed and max rpm?? how do I find this out, donor car was a 1980 ford escort estate 1300cc
built car locost 7


RichardK - 23/5/08 at 07:48 PM

It maybe in a haynes manual that sort of info.

If you haven't got one someone maybe able to point you to a download of one

Cheers

Rich


Schrodinger - 23/5/08 at 07:49 PM

The max speed is to ensure that the tyres you are running with are rated appropriately so I would put something like 120mph.
Max rpm is for engine noise and is measured at 75% of max IIRC but I thought it was rpm for max power. If you have the haynes manual for the car it will be in there (or go to your local library and have a look in there).


djtom - 23/5/08 at 08:16 PM

for max rpm, rev it until the pistons come out through the bonnet, take note of the rpm at which this happens, knock 200rpm off this, fill in form, rebuild engine, set rev limiter accordingly....


Sorry, I started drinking earlier than usual today!

Tom


RichieW - 23/5/08 at 09:34 PM

I can check my haynes manual for you tomorrow if you dont find out before. They provide figs for the rev limit and the max power rpm. Am round the other halfs place at the mo.


StevieB - 23/5/08 at 09:55 PM

Max speed and rpm?

Sounds like a trip to Elvington...


RichieW - 24/5/08 at 11:47 AM

Max continuous RPM for the 1300 crossflow is 5800 (Red line).

Max power is at 5500.

Both according to the haynes mark 2 escort manual.

Your car's theoretical max speed would be

rpm x tyre diameter in inches
------------------------------------ (divided by)
ratio in top gear x diff ratio x 336


for a typical escort with a 4 speed box that could be

5500 x 23
----------------
1 x 3.89 x336


=96.78mph

If you are using a sierra five speed box the ratio would be 0.82 rather than 1.

The ratio for the rear diff is usually stamped on it on a little plate on the back of the diff housing if it hasn't fell off. Otherwise get the wheels off the ground and turn the prop shaft a set number of times and see what the output is from the rear wheels and work out the ratio that way. It could be a 3.89, 4.11, 4.125 or 4.44 to 1. Ford have a habit of using up anything they have got left at the end of production runs so it could be a bit of a lottery as to which you have.