Underdrive pulleys

[CMF_Yom]

Hey all,

Just wondering if anyone has come across lightweight underdrive belt pulleys for our micras?

I've seen the benifits these things have given GA16DE engines in the USA and I reckon we could see equal or even better gains...

Any thoughts/comments/ideas are welcome.

Cheers

 

[CMF_micra-man]

Are you refering to this sort of thing?
http://www.autospeed.com/shop/category_639/browse.html

If so, I believe there was some discussion about them here
https://micra.org.uk/cmf/message/7905

 

[CMF_Yom]

Well I've researched and found my powersteering won't work as effectively, but I'm not too fussed about that as to be honest it is probably a little TOO light under 60km/hr anyway.

Water pump also won't have as much RPM in normal day to day driving, unsure of how this will change the cooling capacity of the car. IF it gets too hot, might have to upsize the pulley on the pump.

Aircon won't work as efficiently at lower rpm. Thats ok, will just need more revs in summer to keep it cool.

Alternator won't charge as efficiently at lower rpm. Will this be a problem?

Trying to decide right now whether an actual underdrive pulley would be suitable or just a plain old billet aluminium remake of the original so its lighter.

Putting this on the list of things to do when I do the clutch at the end of this year...

 

[CMF_Yom]

White Knight, I know you'll read this thread so here's a question for you. You've ditched the davies craig electric pumps, what are you using now?

Cheers

 

[cisco]

I reckon they are potentially more trouble than the small gain you get from them.

 

[CMF_Yom]

Any other ideas of things which could go wrong, apart from the stuff I mentioned?

I guess crank balancing is something to watch out for as well. The pulley would have to be 100% true and equal in density the whole way through.

 

[CMF_kneival]

I would say get a lightened and balanced one - dont bother with underdrive. You would probably see better gains by getting rid of powersteering and air con than underdriving.

Can anyone get the weight and dimensions of a 1.3 pulley? I have a 1.0 pulley here and want to know if its lighter/smaller.

Also a guy called route from singapore installed a lightweight pulley, says you can feel the difference.

 

[CMF_White Knight]

Hi Yom, gone back to the stock standard good old Micra mechanical pump.No doubt it spins about 50% faster due to the larger drive pulley but temp. gauge sits a tad under normal. Mind you I also have a Datrats radiator which is a monster compared to the original.
Hack at full boost ( 7psi) A/C full bore and temp gauge never moves above normal. Hack has stock standard radiator but never seen the gauge move above half way under any condition.

 

[CMF_Yom]

Do you know how much cavitation the standard pumps make when at high RPM?

I had a peek at the micra pulley at the wreckers. I don't know if making it smaller would actually do anything. Hehe its puny compared to the pulleys on cars where underdrive pulley actually makes a difference.

 

[CMF_gu_niang1200]

i would say i know route and one litre pulley is definitely lighter than the 1.3 l march... but same dimension in size. yeah route got himself a fully lighten alloy one.. feels good when u have your air con on... feels light..

 

[CMF_Yom]

When i turn my aircon on at the moment I imagine that it must be pretty similar to driving a 1L micra. And then i think about a 1L with aircon on. And then I think Daewoo Matiz.

Offtopic but yeh, if a lightened pulley makes driving with the aircon on bearable I'm putting it on my shopping list for sure.

 

[mik]

But guys who needs an A/C anyway?

 

[CMF_White Knight]

Come to Australia in the middle of summer and you will find out. mik our seasons are the excat reverse of yours. Summer there winter here.

 

[CMF_Yom]

Yeh its not so much the fact that its overly hot (i can live with the heat) its the damn sun. You get the car to a decent temperature by opening sunroof and windows but you get bloody toasted by the sun. I'm not one for driving with a large hat on either.

 

[CMF_gu_niang1200]

well its hot insingapore... temp ranging 26 - 34deg.. we need a.c on... definitley

 

[CMF_Yom]

Don't forget the humidity.