Craigorypeck
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| posted on 14/10/11 at 08:46 PM |
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supercharger pulley.. too small?
Found some toothed pulleys at the right ratio to run at 2:1 crank speed but I'm concerned that the SC pulley is a bit small (40mm) and will jump
or strip the teeth off the belt when closing throttle at red line, back pressure/inertia will be quite a lot.
Is this a potential problem?? Any ideas would be great before i go ahead and start welding the charger mounts..
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MakeEverything
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| posted on 14/10/11 at 10:37 PM |
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Try the basics and calculating ratios etc against the pressure map manufactured by eaton.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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flak monkey
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| posted on 15/10/11 at 07:33 AM |
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I would personally run a larger pulley than that. Depends more on the belt manufacturers recommendations. Belts have a minimum bend radius for various
loads and speeds.
I would try and increase the sizes of all the pulleys by at least 50% looking at your set up.
Sera
http://www.motosera.com
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Craigorypeck
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| posted on 15/10/11 at 08:07 AM |
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quote:
Originally posted by MakeEverything
Try the basics and calculating ratios etc against the pressure map manufactured by eaton.
I would if I knew how!!??
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Oddified
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| posted on 15/10/11 at 08:18 AM |
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I think the pulleys are to small if that's an m62, if it's an m45 it's a bit on the small side for a modified 2.0L with high
rev's.
I've also been looking at putting an eaton m62 onto my atmo cosworth, and after playing with the calculator on eaton's web site decided
that a 1.7 pulley ratio would be best to stay within the rev range of the charger and lower charge temps.
It also depends if your changing the spec of the engine any or how much (cams/compression) as well???. If it's staying roughly as it is
(guessing on spec's of course), high comp and nasp cams then you'll only be safe putting low boost in (i was aiming for 4 - 7 psi max), or
drop the comp and fit milder/turbo cams and run 1.9 or 2 pulley ratio for more boost.
The only flaw in my plan was buying a merc supercharger, to find it was actualy an m45 so sold it again.
Ian
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Craigorypeck
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| posted on 15/10/11 at 08:18 AM |
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quote:
Originally posted by flak monkey
I would personally run a larger pulley than that. Depends more on the belt manufacturers recommendations. Belts have a minimum bend radius for various
loads and speeds.
I would try and increase the sizes of all the pulleys by at least 50% looking at your set up.
Wish I had stuck with my original plan of using larger serpentine belt pulleys, was having trouble finding the sizes I needed and then stumbled across
your site Flak when enquiring about that bit of lathing on here...
So I might need a crank pulley for a YB then Flak..... I'll send thru a PM
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Craigorypeck
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| posted on 15/10/11 at 09:01 AM |
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Hi Ian, yes its an m45, the slk had both m62 and m45 depending on year..
its a very monkey see monkey do project TBH and not entirely sure if it will work.. I was just gonna run 2:1 on the pulleys and see what boost it made
and then worry bout fine adjusting the pulley sizing after as not sure how its worked out on paper..
CR is 10.5:1 so thought a 6 psi boost might work with the intercooler I have..
The NA cams are high lift Newman phase 2, 288 dur and thought that dialing a bit of overlap out might give a decent result but had considered putting
the standard turbo spec exhaust cam back in??
Any pointers much appreciated.
[Edited on 15/10/11 by Craigorypeck]
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Oddified
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| posted on 15/10/11 at 10:59 AM |
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When i did some research (lots of googling) on the m45, it looked a bit marginal on a tuned 2L engine and is likely to run out of puff at higher rpm.
The 2.1 ratio will probably be needed to get some boost high up, but you'll have to balance the rev limit on the engine to what the supercharger
can safely spin at.
Your comp and cams are relatively mild for a na cosworth, as you say dial out some overlap, knock some timing out on boost and use good fuel you
should be ok up to 8psi. By everything i looked up/worked out, the m45 won't make that though on a modified 2L engine (if it's already
making 200bhp ish) unless you spin it over it's recomended max rpm.
I read somewhere that the m45 physically can't pump enough air to make over 245bhp ish. Don't quote me on that....it's only what i
read somewhere!.
Of course if your engines making say 180 ish now, then an extra 60 ponies is worth having!, plus the massive extra low down torque you get with a
supercharger!.
Ian
[Edited on 15/10/11 by Oddified]
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Craigorypeck
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| posted on 15/10/11 at 11:15 AM |
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Cheers Ian.
currently estimated to be in the 180-190bhp range but all the power is up high, looking for more torque really.. a few extra up top would be cool but
not after mad figures. I'd be very happy with 245 hehe..
Contacted the company i got the pulleys from this morning and they suggested that they would make me wider pulleys to run a wider belt if I run into
slippage problems, which is nice..
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Craigorypeck
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| posted on 15/10/11 at 11:21 AM |
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also running 2.5" od piping all round will this suffice? also my plenum is a pretty poor shape... a lot of corners and squareness, what ill
effects will this have..
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Oddified
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| posted on 15/10/11 at 01:29 PM |
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I don't think it's so much the width of the pulleys that's been suggested above, it's the diameter and the tight radius the
belt is going around that might reduce the belts life.
For the power your looking at 2.5" would be large enough i'd expect, avoid tight/square bends though if possible.
I'm no expert though, just passing on info that i'd found out whilst looking into taking the same path.
Ian
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Craigorypeck
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| posted on 15/10/11 at 06:56 PM |
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quote:
Originally posted by Oddified
I don't think it's so much the width of the pulleys that's been suggested above, it's the diameter and the tight radius the
belt is going around that might reduce the belts life.
For the power your looking at 2.5" would be large enough i'd expect, avoid tight/square bends though if possible.
I'm no expert though, just passing on info that i'd found out whilst looking into taking the same path.
Ian
I see.. I thought the small radius was a problem in the fact that not a lot of belt would be in contact with the smaller circumference so fewer teeth
doing all the work, hence my thinking of a wider belt... wasn't concerned of the tight radius for the belt!
I'm going to end up with a few tight radius elbows to get past the exhaust manifold but that cant be avoided..
Cheers
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