kj280z Posted November 12, 2004 Share Posted November 12, 2004 I wouldn't consider it a design flaw, just an acceptable compromise. I found a guy in southern florida to make my pulley, I'm sure you could do the same for around $175? I did a quick search for pulleys and found: http://www.vacmotorsports.com/cgi-bin/view_item.pl?item_id=377 http://www.bmpdesign.com/ I thought for sure Pulleyboys would have had one. Have you decided how fast you'd like to spin your blower? What is the current diameter of your drive pulley (crank)? I've spoke to Magnuson several times they would like for me to keep it below 16,000 rpms... (and that might be pushing it without a way to cool it down)... I'm certainly going to test it's limits... I know Stillen has spun theirs (MP62) to 18,000 on a few occasions. I can tell you that with my current pulleys when I started it yesterday for the first time it showed an INSTANT 7.5+ PSI of boost with just a blip of the pedal (blip to 1700 rpm from idle) (haven't driven it yet!!!) heh heh heh Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 13, 2004 Author Share Posted November 13, 2004 my crank pulley is 5.6" (SC pulley 2.55") so at 5800rpm the SC sees around 12,800rpm, but if can get a 2" pulley then i'll be pushing it a bit at 16,200rpm (especially if my foot pushes the engine over 5800rpm!!!) It's an old SC and will require new bearings very soon (and there's a chance more than that if i push those rpm) As far as the boost, it is awesome how fast it comes on. Mine goes from 20lbs vacuum to 5lbs boost by 2000rpm then creeps up another pound shortly after. Are you running an intercooler or water injection? The roots SC does generate a fair bit of heat. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted November 13, 2004 Share Posted November 13, 2004 I have a fixed pulley size on the supercharger of 3.5" Dia. with the electric clutch on the supercharger. So all changes have to go on the crank side. 8) Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 13, 2004 Author Share Posted November 13, 2004 Any idea what your M62 came off of? I read that most series2 M62 owners would upgrade the SC pulley from the stock one (3") to a series 1 pulley like mine (2.5"). what other info can you give us...what are you putting on and where/how? Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted November 13, 2004 Share Posted November 13, 2004 I came off of a Mercedes SLK 230 Kompressor. Quote Link to comment Share on other sites More sharing options...
kj280z Posted November 13, 2004 Share Posted November 13, 2004 Mike and SHO-Z, Hey... I started doing some calcs just to see what your ratios would be... I have a spreadsheet that I put together that makes it real easy... if you'd like a copy email me at ken280z@hotmail.com In both cases I believe the 6.75 inch drive pulley that I have would work very well for you guys... Before I share the numbers with you, there's one other thing to consider ... clearance...when trying to increase the crank pulley size to anything larger than around 7 inches... I couldn't use my electric water pump and had to go back to the stock H20 pump. You might have similar issues but since you've placed the SC in different places you'll have to figure that out. OK... So the numbers... Mike... you seem to have 2 SC pulleys 2.55 inches and 3 inches. With a 6.75" drive pulley and 3 inch SC pulley (2.25 ratio) at 7000 rpm you'd be spinning the blower to 15,750... at 5800 you'd be at 13,050... Might be pushing it but a good place to start. If that worked out ok and you wanted to try to push it further, the 2.55" pulley would yield a 2.64 ratio and 18,529 rpms at 7000 and 15,352 at 5800 rpms... I'm not sure what a M62 can be spun to, but if it's the same as a MP62 I believe the 2.55" pulley would be pushing it slightly beyond it's limits but it has been done before. I'm pretty sure that if you put water injection on it you'd be able to get there (I'm going to run water injection on mine). SHO-Z I LIKE the idea of having a clutch type snout and I have heard of aftermarket pulleys being made for them. If memory serves me correct you can get a 2.75 inch pulley for your blower. Either way, again after doing the numbers, I believe that a 6.75 or 7 inch drive pulley would be ideal for you as well... Here's why... At 5800 rpms with your current 3 inch pulley and a 6.75 inch pulley your SC would be turning 13,050 and peak at 7000 rpms at 15,750... not too bad! If you were able to get the 2.75 inch pulley, the numbers change to 17, 182 at 7000 and 14,236 at 5800 again not bad! If you got the 7 inch drive pulley and kept your 3 inch SC pulley it would be 16,333 at 7000 and 13533 at 5800. I think it's best to calc your drive pulley size to be within your desired "window" and then make your changes on the blower side, but that's just me... Hope this helped... Ken Quote Link to comment Share on other sites More sharing options...
kj280z Posted November 13, 2004 Share Posted November 13, 2004 I finally got this right! Always had trouble posting a pic... This is my 6.75" custom pulley which bolts to the 82/83 damper. Ken Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 13, 2004 Author Share Posted November 13, 2004 just out of curiousity...how often do you plan on hitting 7000rpm?!!!! haha -push it hard and hope for the best. Quote Link to comment Share on other sites More sharing options...
kj280z Posted November 13, 2004 Share Posted November 13, 2004 7000 RPMs is my redline and I hope to see it often! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.