Idler Pulley - Needed? - Boost Forum

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Idler Pulley - Needed?
Wednesday, June 27, 2007 6:45 AM
Hi all,

I'm building a supercharged Eco for my Speedster (If you are interested lookHERE)
One question I have is - Do I need a idler bracket+pulley?

Thanks,
Steve



Power Curve

Re: Idler Pulley - Needed?
Wednesday, June 27, 2007 6:21 PM
Without it you're gonna have to figure out an alternate way to route the belt. If you're not using an A/C compressor, your chances would be improved, but I don't think you can pull it off based on where the tensioner and alternator are located.



14.330 @ 96.37mph
Re: Idler Pulley - Needed?
Thursday, June 28, 2007 8:25 AM
Thanks Bill.

I was thinking about getting the pulley boys setup...

CLICKY





Power Curve
Re: Idler Pulley - Needed?
Thursday, June 28, 2007 9:05 AM
either youll have to go custom routing , or use all the stock LSJ pieces and belt routing

and going the stock LSJ set up is prob gonna be the easiest to use







Re: Idler Pulley - Needed?
Monday, July 02, 2007 1:54 PM
Thanks 97trd... Am trying to round up the stock part numbers.



Power Curve
Re: Idler Pulley - Needed?
Monday, July 02, 2007 6:25 PM
damn man you lowered compression to 8.9.... bad idea !! a 10:1 compression forged engine would easily withstand all the supercharger could give and be much more powerful !!



14.083 @ 99.746 mph GMPP s/c intercooled on drag radials.
Re: Idler Pulley - Needed?
Wednesday, July 04, 2007 2:52 PM
DanteMustDie wrote:damn man you lowered compression to 8.9.... bad idea !! a 10:1 compression forged engine would easily withstand all the supercharger could give and be much more powerful !!


Yeah, I've been thinking about this. She's not complete yet so I can still change the pistons and CR. This engine was supposed to be turbo'd hence the drop to 8.9 compression. As I want to supercharge I'm thinking maybe your right, bring back up the compression. But I've still not made up my mind!

Have a look at these two graphs and let me know your thoughts.

CR Under Boost

Boost and IC Efficiency

She also has turbo cams which have a lazy ramp, wondering should I plan to use some with less ramp and more duration?





Power Curve
Re: Idler Pulley - Needed?
Sunday, July 08, 2007 1:47 PM
Quote:

damn man you lowered compression to 8.9.... bad idea !! a 10:1 compression forged engine would easily withstand all the supercharger could give and be much more powerful !!


If you only plan on using race gas from now on.




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Member Option D Racing
Re: Idler Pulley - Needed?
Sunday, July 08, 2007 2:19 PM
Option D wrote:
Quote:

damn man you lowered compression to 8.9.... bad idea !! a 10:1 compression forged engine would easily withstand all the supercharger could give and be much more powerful !!


If you only plan on using race gas from now on.


not at all... most turboed Js on here still are on stock engine with the stock 10:1 compression, I haven't heard about any of them having issues with running premium gas with their setup. Many of them hit 300 whp without a hiccup



14.083 @ 99.746 mph GMPP s/c intercooled on drag radials.
Re: Idler Pulley - Needed?
Thursday, July 12, 2007 5:30 AM
How much power do you think I'll be dropping with the lower compression ratio?



Power Curve
Re: Idler Pulley - Needed?
Thursday, July 12, 2007 8:36 AM
why not stick with the turbo?





Re: Idler Pulley - Needed?
Thursday, July 19, 2007 7:38 AM
There a few reasons why I want a supercharger over a turbo.

First, the power delivery profile of a supercharger is more to my liking. With such a light car 300+ HP and lbft of torque needs to be delivered as smooth as possible.

A supercharged engine fits in the engine bay with no chassis modifications meaning installation is easier.

I won't have some of the heat issues some of the 300-450 HP turbo Speedsters are suffering from meaning I've got a setup that has a good lifespan. Basically a high power vehicle I can drive 'normally'! Chargecooling/Intercooling and cooling a big turbo on a mid-mounted setup with limited engine bay space can be a challenge, especially if you want it as your daily driver and don't want to install any specialist cooling mods. IMO an supercharger makes the problem of 'big power' heat more managable and drives down the risk associated with boost.

Finally all the above helps cost, I'm getting more HP for my buck with the supercharger.





Power Curve
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