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Why such a small sump?

Posted: Sun Oct 22, 2017 10:32 am
by Sprite
Just doing my "put it away for the season" oil change and I'm curious again why the 4age 20 valve has such a small oil sump. Around 3.2 liter depending on whether you have an oil cooler and the size oil filter you use. Does anyone know the engineering rational behind this. :?:

Re: Why such a small sump?

Posted: Wed Nov 29, 2017 11:10 am
by mad_86

. I noticed that also, the oil sump. (Oil pan) is very different in size also it the 16v 4age oil sumps are bigger!

I was thinking has to do with oil cooler that is used on the 16v 4age. 20v dont come with oil cooler iicr
But not sure.

Also my next motor will be built in a high comp block, same specs as 20v block but with oil drain and squirters and bigger oil sump 16v

Re: Why such a small sump?

Posted: Wed Dec 06, 2017 2:25 pm
by jondee86
Good question :) I don't know the exact answer, but I can think of a few reasons why
the AE86 sump is the size/shape that it is. To keep the hood line low the engine has to
sit as low as possible. Only this means the sump gets closer to the road, and it has to be
tucked up high enough to be out of the way of accidental scraping damage.

On the AE86 the bottom of the sump is about 1/4" higher than the front crossmember.
The position of the front cross member also dictates that the sump be a "front bowl"
design, as that is the only place where a bit of depth is possible. The rear part of the
sump has to be shallow as it sits on top of the cross member. So packaging issues.

The 4AGE is a water cooled engine, and as such, the engine cooling system will take
care of keeping the oil in a stock engine at an acceptable temperature. Additional oil
cooling only becomes necessary when the engine is modified to produce a lot more power
(and heat) than stock. Or the engine is subject to continuous operation at high loads
(towing) or high temperatures (Death Valley).

As far as the quantity of oil goes, there has to be enough to maintain full flow thru the
engine at all times. This means taking into account how much is in the galleries and head
while still keeping the pickup submerged. In this respect a small, deep sump is good, and
also helps prevent the oil moving away from the pickup under lateral acceleration. The
stock AE86 sump seems to be fine for stock and mildly modified engines.

Race and rally engines that are liable to sustain high rpm and high lateral acceleration
on bends need to take special precautions. They need to ensure that there is adequate
cooling and sufficient oil quantity to keep the pickup submerged under high lateral G's.
Winged and gated sumps (or dry sump) and an oil cooler are more or less standard
modifications for these engines.

Cheers... jondee86

Re: Why such a small sump?

Posted: Thu Dec 07, 2017 2:45 am
by Rogue-AE95
Also of note is that the RWD oil pan is different than the FWD oil pans. It has grooves in the bottom of the lowest part of the pan, running front to rear (looking at the timing belt side of engine), whereas the FWD pan does not.

Re: Why such a small sump?

Posted: Thu Dec 07, 2017 9:38 am
by oldeskewltoy
much more significant..... the earlier rwd pans are 4 quarts, while the later pans are less volume. If you look at the pan from the front of the engine, there is a "kick-in" on the intake side (axle side in transverse layouts).

having more oil available is never really a bad thing... the MRP pan is 4.8 liters (5 quarts) so having 25+% more volume helps keep the oil cooler, and allows for sustained high rpm operation.

About 10 years ago I was working on a simpler/cheaper solution then the MRP pan.... also 5 quarts... "Batpan" ;)

this is/was the prototype...