SR water pump no good after 6000 rmp's???

Post by **nismojason** » Wed Jul 30, 2003 8:10 am

I was reading the new sport compact car and they have a section about all the different engines that you could drop in the 240sx. They said that the SR was a good engine, but that one of its main flaws was that after 6000 rpm's the water pump is past efficiency, and after the water temp gets above that point it won't come back down. I've never heard of this being a problem, they said that the way to combat this prob is a big radiator and a underdrive pulley to slow the pump down. Anyone ever heard of this problem.

Post by **Cyberkreig** » Wed Jul 30, 2003 8:10 am

by 6000 RPM the SR powered car has far more air moving over it than require to keep it cool. =)

Post by **hurddawg** » Wed Jul 30, 2003 8:10 am

yep. all the sentra se-r/g20/200sx/nx2000 guys know about it. Most that road race the SE-R use underdrive pulleys from Unorthodox racing.

Post by **nismojason** » Wed Jul 30, 2003 8:10 am

does UR make just a water pump pulley for the rwd SR

Post by **hurddawg** » Wed Jul 30, 2003 8:10 am

i think i have heard that they are working on a set, but not sure. You can email them to find out for sure.

In the interim, you can get JUN's improved water pump for about $400

Post by **Movingviolation240** » Wed Jul 30, 2003 8:10 am

just run a heavier pressure cap on your radiator, that will help reduce the cavitation caused overheating.

Post by **BuudWeizErr** » Wed Jul 30, 2003 8:10 am

Or just get a Koyo for an extra level of insurance.

It amazes me how people will drop 3 grand on performance parts, but won't spend a couple extra hundred bucks to keep it running in top notch condition.

Post by **S13240** » Wed Jul 30, 2003 8:10 am

Movingviolation240 wrote:just run a heavier pressure cap on your radiator, that will help reduce the cavitation caused overheating.

You know anything about popping your radiator hoses by upgrading your radiator cap? I've read some cases that people would upgrade their radiator cap to a heavier pressure one and after a while the radiator hoses would blow up or something because of the extra pressure. Maybe they just needed new radiator hoses?

Post by **nismojason** » Wed Jul 30, 2003 8:10 am

that doesn't seem right since that hose isn't really under any pressure, it just continues to flow into the tank then that would overflow. Atleast thats how it seems to me.

Website · Post by **s13sr20chris** » Wed Jul 30, 2003 8:10 am

hose clamps loose?

Post by **teriyakibroccoli** » Wed Jul 30, 2003 8:10 am

yea, any extra pressure would cause the coolant/water mix to flow into the overflow resevoir

Post by **Movingviolation240** » Wed Jul 30, 2003 8:10 am

I've got this funny feeling that half you guys don't know what your talkin about....

The higher pressure will cause the hoses to be under more pressure, but only a few extra PSI, if they blow up they needed replaced anyhow. End of story.

A Koyo radiator would not help that cavitation issue one bit. All that will do is give you more cooling capacity.

The higher pressure cap will make the system run at 1bar insted of .9 bar before venting the extra pressure back into the catch tank.

Paul

Post by **Def** » Wed Jul 30, 2003 8:10 am

Movingviolation240 is right. A higher pressure radiator cap will increase the vapor pressure of the coolant, resulting in less cavitation.

Speaking of UR underdrive pullies, has anyone ever heard/seen is they affect the main bearings of SR motors much? I know in longer stroke Honda motors like an H22A a crank pulley can eat up the mains in less than 20-30k due to the second order harmonics not being damped by the rubber ring in the stock crank.

Post by **hurddawg** » Wed Jul 30, 2003 8:10 am

i haven't heard much about it, on the Sr20de forums. Only problem with bearings that i've heard/read is holding 7000+ rpms for too long and spinning the bearings or no oil pressure and then spinning the bearings.

Post by **hurddawg** » Wed Jul 30, 2003 8:10 am

LOL I just read the article from SCC and it even states in there that unorthodox is making pulleys for the rwd sr. The S14 one should be available now, and S13 ones soon after!

Post by **RobDET** » Wed Jul 30, 2003 8:10 am

the stock sr crank pully have rubber rings? I had a UR single accessory pulley on my B16 honda but it had a solid pulley stock.

Post by **hurddawg** » Wed Jul 30, 2003 8:10 am

I can speak only for the FF sr20, but yes the stock crankpulley hasrubber rings in it. I don't know of any car that has accessory pulleys with a dampner in it.

Post by **S13240** » Wed Jul 30, 2003 8:10 am

Movingviolation240 wrote:I've got this funny feeling that half you guys don't know what your talkin about....

The higher pressure will cause the hoses to be under more pressure, but only a few extra PSI, if they blow up they needed replaced anyhow. End of story.

A Koyo radiator would not help that cavitation issue one bit. All that will do is give you more cooling capacity.

The higher pressure cap will make the system run at 1bar insted of .9 bar before venting the extra pressure back into the catch tank.

Paul

Hey I didn't claim I was smart that's why I asked you if you knew anything about it. And you answered it so thanks.

Post by **Mikel** » Wed Jul 30, 2003 8:10 am

It happens in pretty much all stock water pumps, it's called cavitation.

Way more than you ever wanted to know about it:http://www.gewater.com/library...p.jsp

Basically, you just need to slow the pump down if you're going to be running high engine speeds for extended time periods. DO NOT do it if you're going to be driving it on the street, it will overheat.

Website · Post by **s13sr20chris** » Wed Jul 30, 2003 8:10 am

Def wrote:Speaking of UR underdrive pullies, has anyone ever heard/seen is they affect the main bearings of SR motors much? I know in longer stroke Honda motors like an H22A a crank pulley can eat up the mains in less than 20-30k due to the second order harmonics not being damped by the rubber ring in the stock crank.

according to mike kojima nissan engines are internally balanced to the point where a harmonic balancer for the accessories is just an nvh issue. so, tell all your honda friends what i tell mine. nissan is better.:pface

SR water pump no good after 6000 rmp's???

SR water pump no good after 6000 rmp's???

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