need oil for high output go-cart.

[cryptokid]

running a engine which turns 8000rpm's on a highly modified lawnmower engine. it sees cylinder head temps in excess of 500 degreesF. the horsepower measures on a dyno is over double that of stock.
running 9:1 compression on a ported and polished tecumseh 7hp engine. the deck has been shaved to the point that the piston protrudes out of the cylinder, the cylinder head is flat, the only thing keeping it from hitting the head is the headgasket. the cylinder head has been shaved as well as hogged out for better flow. the intake and exhaust ports have been ported and polished and port matched to the intake manifold and carborator. running triple stage header and aftermarket camshaft and springs.
it has splash lubrication so id like somthing thin when cold, but really thick when hot. i live in south florida so i dont need a very thin oil when cold, maybe 5w or so.
does anyone make like say a 5w70?
because of the excess heat and splash lubrication, i also need somthing with a very high flash point, and also somthing that resists shear EXTREMLY well, basically very little viscosity improvers are wanted in this oil.
i know this would make for an expensive oil, but im willing to pay for it.
id like to stick to brand names. will consider anything otc, amsoil, redline and royal purple.

so, what do you guys suggest?

 

[Cujet]

I do not know of any 5W-70 type oils. However, the situation you describe is not that different from other highly loaded engines. As a matter of fact I would suggest that the engine loading you are seeing are well within normal ranges for modern engines.

Aircraft engines and Harley Davidsons suffer from some of the same conditions you describe. The age old Harley solution was to use Aircraft oil! You may want to look into using Aeroshell 100 or a high viscosity Harley Davidson oil. Those oils protect well during startup and leave a good film after shutdown. The main reason these oils are used is that they are thick enough to provide protection when engine temps are at 500 deg F.

Are you really needing a light viscosity for cold startup?

Mobil 1 15W-50 protects very well and is very heat tolerant, however some air cooled (generally the older engines) Harley users say it is too thin for high temp protection. My guess is that it protects those Harley engines well, however it burns or leaks out and oil consumption is a problem. That would be the best reason for not using it in an older Harley.

Chris

 

[JohnBrowning]

Check out Redline! Depending on your preferrence you can get a multi weight type oil with full aditive package like a street engine or oils designed just for raceing. THe race oils are single weight oils while the oils are multi weight. With splash only oiling I would not get anythicker then 10W40 or straight 30-40 weight. NEO oil make a heavy oil for Nascar and Winston Cup raceing. They do not list it's exact viscosity but they call 570??? You might try calling NEO and asking about it if you havce you heart set on a high Vis oil. P.S. Redlines 10W40 is pretty good stuff. It exceeds convetional 20W50 shear strtength by a large margin!!

 

[JohnBrowning]

I think that Amsoil and NEO both sell an oil made specificly "supposedly" for high output go-kart's!

 

[Bror Jace]

'Kule said that for splash lubrication, the 40 weights work the best. Assuming he's right, I would look no further past Red Line straight 40 weight racing oil. It's still thin enough to allow easy cold weather starting.

Change 2-3 times each year to prevent corrosion or more frequently depending on how often you race.

--- Bror Jace

 

[theguru]

Hi,

Your heat situation and RPM are not too different to many small 4 cylinder sports cars (especially turbos). Many of these run up to that RPM and beyond. They also get hot. My sons Nissan 2L turbo has the turbo and exhaust glowing candy red after a quick run. Pretty Hot!

He is using a Motul racing Oil 10w-40 (ester based) or you could use one of the Redline oils Either street or racing oils. They are also ester based.

You didn't say the size of pan. Probably not very big. I think I would change the oil reasonably regulary. A small quantilty will not last as long.

As far as bottom range, I don't think this is as important as you top viscosity. Your cart is not being driven the same as a car. In racing situations it is the high loads/ high/ heat/ rpm that are going to kill the motor. You will rebuild the motor well before wear caused by cold starts would ever be a problem. Besides, how about pulling the motor over a few times with the ignition off to make sure you have oil through the motor, then start it.

[ June 07, 2003, 08:27 PM: Message edited by: theguru ]

 

[clutchless]

Redline also makes a Kart oil. It is called 4 stroke Kart oil. I think the viscosity is around 5w-20.