im building a 489 for my 70, and i noticed from a search some guys are using the 20403-not sure what the diff is between the 20401 and 20403, $50 diff but on summit specs seem to be the same(i did'nt want a kick out pan, thought that was what the 01 was, but pic shows it as kick out))
thanks

I believe the difference in those numbers is the 20403 has a scraper and windage tray built into the pan and the 01 doesn't. I have the 20403 on my 540 .

The 20403 has a built-in scraper of sorts and a screen windage tray in the bottom that is held in by screws and captive nuts. The 20401 doesn't have these.

I just finished a 489 this past weekend that had the 20403. The Eagle crank/H-beam rods hit the screen slightly so the screen had to be clearanced. Be aware of this.

I would use the 20401 or I would take the screen out of the 20403 if you have one already. If you leave the screen in, the 4 1/4" stroke of the 489-496 gets too close to the bottom of the pan to allow good oil return to the sump from the front of the motor, I feel.

With a 4" stroke, there would probably not be an issue with using the 20403 with the screen.

Randy

BTW, If you use the 20403, remove the screen and clean the metal particles and welding slag out from under it before you use the pan.

With a stroker you need the windage screen.

thanks for the info-i intended to use the stock windage tray, it cleared the stroker when i mocked it up, was worried the pan would interfer with the windage tray-sounds like if i use the 20401 might be ok

With a stroker you need the windage screen.
Can you explain more of this?

now im thoroughly confused i purchased the 20403 because it had the windage screen. I thought that was a good thing heh. What dynamics are we getting into here? does anyone run the 03 on a 4.25 with the screen in?

Another question why would this pan have notched rails for a stroker crank ( obviously a stock stroke would not need them ) then be made too shallow in the front to allow the use of their included and welded in windage tray? Thats kind of insane to me. BTW i think mine is welded in place ill look again.

thanks

The Moroso 20403 pan is a great part with the built in's already there. It is designed to clear up tp 4.25" strokes. My pan of choice! :D

I have that pan on my 540 with a 4.25 stroke and it works fine.

Can you explain more of this?

Stroker engines use to be big budget builds using Lunati, BRC, Moldex, Callies, and other crankshaft brands. Counter weight profile on these cranks were contured and tested in in control simualtions as to how they affected the oil pan area with windage. Rotational movement of the crank cause wind currents, high pressure, and this has to go somewhere. Crank mfgs paid attention to the leading edge and trailing edge of cranks to reduce windage.

Fast forward hear to the last 10 years. The import cranks have made stroker engines as common as .030" pistons. These cranks are affordable and for the most part a good bang for the buck. The counterweights on a lot of these cranks are of OEM design. . . that is 2200 rpm going down the road, not 6500 rpm. Add to that with a stroker to make it easier to balance you add more counterweight area. Now we higher rpm and more area in some pan configurations that were designed for OEM specifications.

A windage screen is a must for a stroker engine or an engine that is going to see high rpm. When the high pressure windage created by the crank hits the screen it helps to dissapate the pressure to the low pressure side of the crank. . .effectively absorbing the energy. It has been our finding through R&D with OEM's, drag racing, and circle track engine builders that a screen type windage tray is most effective.

Note this Nascar mandates the oil pan dimensions on those cars. Wonder why?

While I fully agree that the screen is necessary in the pan and is a good thing, I just wish there was more clearance between the pan and the crossmember to allow lowering the floor of the pan a bit.

That being said, I like the 20403 pan for a budget pan, expecially on 4' stroke motors. Just be sure to check the fit with a 4.25" stroke before glueing it down. ;)

Like I said before, also bed sure to clean under the screen thoroughly before using it the first time.


Randy