Board logo

z cars top job
woodster - 10/4/09 at 01:07 PM

in these days of jobs being axed this is a nice change and a dream job

http://www.zcars.org.uk/index.htm

Danozeman - 10/4/09 at 03:22 PM

Nice.

I bet this is a rare bit of kit.

linky

NS Dev - 10/4/09 at 05:42 PM

lol don't ask about that one

Hellfire - 10/4/09 at 05:57 PM

Whatever happened to that? I remember posting about it a few years ago. Things obviously didn't go according to plan......

Phil

NS Dev - 10/4/09 at 06:09 PM

you got it!

My (admittedly rather sceptical on a good day) mate who runs ultima was rather confused by the whole affair (chris allanson had contacted them re. the project) especially as their then current, carburettored 2wd chevy demo car was demonstably quicker than the 4x4 twin engine turbo version.

They now have another 150hp more than they did then in the demo car.

They also have another "fair bit" waiting in the wings for when somebody tries to break their records. Sworn to secrecy, but I'm sure googling twin turbo 6.3 litre small block chevy will show up some interesting engineering

[Edited on 10/4/09 by NS Dev]

richardR1 - 10/4/09 at 07:06 PM

Was down at Chris Allanson's last week and the Ultima was in the workshop. Just had a few tweaks and has more power. He does produce some exceptionally well engineered vehicles.

NS Dev - 10/4/09 at 07:10 PM

He does indeed, but then I also see the odd bit of rather worrying stuff too!

Anybody else looked at the chain lengths on some of the bike engine minis he's done.

I'd love to hear how many minutes they go between re-tensions.

I was worried with 500mm shaft centres and the mini turbo busa at NEC last year had the driven and driver sprockets nearly touching

cloudy - 10/4/09 at 07:36 PM

I also have a very short chain - whats the theory behind shorter chains being a problem?

They obviously need far finer alignment, but presumably the top run of chain has the same force per link as a longer run?

clanger - 10/4/09 at 07:51 PM

quote:
Originally posted by cloudy
I also have a very short chain - whats the theory behind shorter chains being a problem?

They obviously need far finer alignment, but presumably the top run of chain has the same force per link as a longer run?


You hit your own nail on the head so to speak.
The way I look at it (I'm far from expert), for example:
200BHP over a 10 link run = 20BHP/link load carrying ?
200BHP over a 20link run = 10BHP/link load carrying?

So my theory is the longer the chain run the more power is distributed between each link, and the less force and resistence to wear each link has to endure?

Too simplistic? but my missus thinks I'm a bit simple anyway

[Edited on 10/4/09 by clanger]

les - 10/4/09 at 08:57 PM

The force is transmitted through each link on the driven part of the system, so they would all be taking the full 200bhp I think- but you are right- the longer the chain the less wear.

of course i could be totally wrong!!!

Les

NS Dev - 10/4/09 at 09:37 PM

The power is taken by every link, "only as strong as the weakest link".......

the alignment is fine as long as its done right, that's also not the problem.

The trouble is heat buildup and wear. Chains should be specified so that a substantial part of their path is in a straight line, allowing them to cool down. (they heat up as they pivot under load around the sprockets) If they don't cool enough, they wear very fast.

Also, for a shorter chain, each link undergoes more stress per unit time running, again causing severe wear.

Look at the reynolds industrial chain sizing guides online for clues.

pretty much any automotive chain drive is outside their recommended parameters, but obviously the shorter the path, the worse the problems.

cloudy - 10/4/09 at 09:42 PM

Excellent answer - thanks