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#1 (permalink) |
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Senior Member
Join Date: Dec 2007
Location: Macomb MI
Age: 24
Posts: 277
Sean
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Some S/C math for you guys running comptech kits
I have only been here a little while, but I figure I can post up some little bits of information I stumble across to help you guys out.
For you guys running this kit you are running a mp62 gen 4 Eaton blower. Pretty much the same blower as my car (cobalt ss/sc gen 5 m62) except for a slightly different outlet. Onto the important stuff. Your s/c pulley size is 3.6", im not totally sure about this measurement as it was info from another thread, but your stock crank pulley is 5.8125". So you divide 5.8125" by 3.6" to give you your ratio between the to and you get 1.614583. You then take this number and multiply it by your engines max rpm ( 8000 with stg1 right?) and this gives you the rpms of the s/c = 12916 and some change. So what does any of that mean? Well its actually pretty important because your blower is creating a lot of heat when you spin it hard. The max sustained rpm you want the blower at is 14000 rpms and a instantaneous rpm of 16,000. When you pulley down more obviously more heat is to follow and heat is the enemy of power. The difference between your iat1 (intake air temps) and iat2 temps will start to grow more and more as you pulley down making a intercooler and anything to cool that charge of air down your friend. Onto some more math. Lets take comptech stg2 then shall we. 3.3" s/c pulley and a 5.8125" crank your ratio = 1.76136 * 8400 rpms = 14795 and some change. So with that simple stage upgrade you have upped your blowers rpm to a screaming 14795 rpms with no way of cooling that charge. When your cars intake temps get to hot your car will in turn start to pull timing because the air is to hot and will start causing knock. So what can we do to combat this power loss? Well a simple answer would be well the intercooler. Im not totally sure how far along anyone would be on that project, but once it is finished I would highly suggest it. Not only for the power to be had but to be safe as well. You guys aren't there yet but if you start to pulley down more and get into some higher rpms it also has negative effects on you blowers life. A scan gauge would be a good investment as well, im not totally sure what parameters it measures for you guys but typically it has iats, knock, boost, and some other important parameters. If they ever came out with a tuner for your car i would highly suggest meth injection for the cooling as well as the increased ability to run more timing. A egt is also a handy tool to use to let you see the temps inside your motor because to much heat in there and motors have a tendency to go pop. You can be running a 11.5 afr no knock but if you don't know what’s going on in there and you pop a ring land that might answer your question. If you guys have any specific questions i will try to be as helpful as possible. Thanks for your time Sean |
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#7 (permalink) |
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Senior Member
Join Date: Jun 2006
Location: Greensboro NC
Age: 28
Posts: 4,101
Dustin
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i thinks we need to get RedshiftChris in here to shed some light on this issue, they have done extensive real world temperature testing of the eaton blower on the RSX-S (same engine) and determined that the blower was fine on our motors up to like 8 psi with out being cooled.
you can read all the info the got from testing the eaton roots and the lysholm twin screw here. they determined that the eaton wasnt a problem until 11 psi. RedShift Message Board :: View topic - IAT Testing - New Info |
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#11 (permalink) |
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Senior Member
Join Date: Mar 2006
Location: PM me NothernNJ Detailing
Posts: 4,022
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The Eatons run hot at the edge of their efficiency map...8 psi peaked at 192 deg on the Roots charger....At the 12 psi boost level the only time it would stop making heat is when the MAP was around 10" vacuum and less. I wouldn't do more than 8psi on the roots without cooling..
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#15 (permalink) |
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Senior Member
Join Date: Jun 2006
Location: Greensboro NC
Age: 28
Posts: 4,101
Dustin
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Another thing to keep in mind is the fact that the eaton blower is equiped with a boost bypass valve so its not creating boost all the time. Its not like the blower is always running at extremely high temps when just cruising. I think you would have to beat the crap out of it for a prolonged period of time before any overly high temps come into play. I can say that after a spirited ride my eaton blower is warm to the touch but not extremely hot.
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#17 (permalink) |
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Senior Member
Join Date: Nov 2007
Location: Simi Valley
Age: 27
Posts: 3,950
Mike
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theres no boost at low cruise but its still creating heat because the small pulley is still spinning it but its just bypassing the boost right?
im thinkin 8-9 psi is about as much as one would risk without cooling. |
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#19 (permalink) | |
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Senior Member
Join Date: Dec 2007
Location: Macomb MI
Age: 24
Posts: 277
Sean
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Quote:
I like the iat graph though that is awesome as well. One question though i could not figure out were they both no intercooled? |
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