For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. This is where the DSM platform history is documented and archived. Log in to help us in our mission, and to remove most ads from the browsing experience.
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Dayco 5040410 And you might need to trim the lower timing cover where the timing degree indicator is embossed in plastic so the belt wont rub on it.
you wouldnt happen to have any idea what size.depth the bolts are would you? or have a picture of what you mean about shaving the embossed timing mark.,
, since I had my Magnus intake off I decided to install a Bosch CS130 rebuilt and pull the junkyard one off before it fails at some random time, then I would be forced to pull the intake somewhere inconvienient to get to the alternator, I also decided to install a nice billet 3 1/2" underdrive alternator pulley to slow it down since I was losing output at 5k and above and just running on battery in that rpm range.
Cool setup, but I have a question:
That's interesting. So no tensioner needed!
It's possible, yes, but not recommended because running the belt on the smaller diameter water pump will cause cavitation in your cooling system and you'll damage/blow-up your water pump. The outer track on the OE crank pulley and outer (larger) WP pulley rotate at a 1.07:1 ratio, meaning when the crank is rotating at 8000rpm the WP is spinning at 8560rpm. If you run a belt on the inside track of the crank pulley to the small water pump pulley when you delete your PS and relocate the alternator the crank/WP pulley ratio goes to 1.76:1. So, when the crank is wrapped out to 8000rpm the WP is spinning at 14080rpm.
Aisin said:
https://www.dsmtuners.com/threads/6-bolt-waterpump-pulley-solution.469099/
It's not "so they say", it's actually a fact that this occurs if you're running a propeller outside of it's designed RPM range. If you're basing your reasoning on "well look at the diameter of the alternator pulley" then there's no sense of even having this discussion, just because two things have pulley's doesn't mean the way they function is comparable. Even still, it's not a bad idea to reduce the alternator pulley ratio either, as long as you're able maintain sufficient voltage at idle (low rpm).
The reason why pulley ratio from the crank to the water pump is so important is due to pump speed (the water pump moves fluid unlike the alternator) and if it rotates too fast it will cavitate. As I'm sure you're aware, water boils at 100*C (212*F) at atmospheric pressure (14.7psi at sea level) but by running a pressurized radiator cap (OE is 13psi) you're also effectively increasing the boiling point of the water in your cars cooling system because you're raising the pressure from atmospheric by 13psi taking it's calculated boiling point from 100*C (212*F) to 118*C (244.4*F). When you induce cavitation into a pressurized cooling system (by spinning the water pump too fast) you're creating low pressure zones on the propeller which induces steam pockets in your cooling system, considerably lowering its boiling point. This is only relative to the negative effects of what will happen on your cooling systems ability to cool the engin, I'm certain that Aisin (the company who manufactures the water pumps for our DSMs) didn't design them to rotate at nearly twice the RPM either so who knows how greatly you're reducing the life of the pump itself, cavitation aside.
If you're skeptical, here's a nuts and bolts video as it relates to cavitation.
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I actually emailed Aisin regarding their water pump propeller design in May of last year and after a few back and fourth emails I was told that this was proprietary information that they couldn't share.
It is a bit speculative without info from Aisin but Mitsubishi worked with Aisin on designing a water pump with a crank pulley ratio of 1.07:1 (8000k:8560k) and you're running it to 1.76:1 (8000k:14080k) I would bet you're seeing a significant increase in your coolant temps on a 1/4 mile pass from start to finish due to cavitation.
Good idea.
Unorthodox racing, a supporting DSMTuners site vendor, has also mentioned that they can create any specific pulley size you ask for if they can get at least 10 people to buy it in a group buy. If you don't feel comfortable running a belt without a tensioner I'd recommend trying to get Unorthodox racing to get a group by going.
