In an effort to reduce the amount of hacking I have to do/pay to be done to the firewall/transmission I want to try to lower the motor as much as possible without eating into the ground clearance too much. With that in mind I have taken a closer look at the oil pan in the 20b, FD, and RX8. Here is what I have found. All measurements were taken from the deepest point.



RX8: 45mm -RX8 forum member



RX7: 85mm -Rotary News article stating that the RX8 pan is 40mm shallower than the FD pan.



20B: 101mm. -Measured by RotorMtr's father at the deepest point. He said 'about' 4" so I don't have a lot of faith in this number. If someone can confirm I'd appreciate it. Otherwise I'll have the engine builder verify it later this week



If the above info is correct the RX8 oil pan is less than 1/2 the depth of the 20b pan. Is there any reason the 20b pan cannot be reduced to 45-50mm while still having an adaquate safety margin for oil slosh under high Gs? Bear in mind that the stock 20b pan does not cover the length of the block (see attached pics).

What we do with the motorbike engines to stop oil surge is insert a baffle plate between the engine and sump. You could also weld a little cylinder around the pickup which would further help, provided it doesn't stop the flow.



http://www.iol.ie/~locoblade/build/g.../sumpready.jpg



Mark

the rx8 pan isnt deep but its almost square, you need to keep the right amount of volume in the pan too.



put the engine in the car, and build the pan around it.

dry-sump.. you cheap ass.

[quote name='GreyGT-C' date='May 30 2005, 10:04 AM']dry-sump.. you cheap ass.


[/quote]



To reduce the height by 2.5" it costs ~$500. To reduce the height another 1.5" it costs $2,500 https://www.nopistons.com/forums/pub...DIR#>/ohmy.png Thanks, but I'll leave you to explore the 20b realm of diminishing returns.

There's not a whole lot of room under the bonnet of the car I'm building, so this issue pops up regularly with builders. The main solution is to shorten and square it off to keep the capacity, and some effective internal baffling. If that's not enough you can weld wings to the sides, and shorten it more but bear in mind you're not going to be able to shorten the bell housing! Don't know about rotaries, but most engines can stand to lose a little capacity.



Mark

And $500 is way to much if that's a steel sump.



Mark

[quote name='inanimate_object' date='Jun 1 2005, 12:31 AM']And $500 is way to much if that's a steel sump.



Mark


[/quote]



Thanks for the Reply Mark. Does the Baffle reduce oil slosh by eliminating the free space that is normally between the oil and the block?



I am concerned about reducing the capacity. Hopefully I can make up for the drop in capacity with two large oil coolers. You're right I could also expand the pan laterally.



I agree, $500 is conservative. However, given the way things are going it wouldn't surprise me if it cost 2x as much.

[quote name='ccarlisi' date='Jun 1 2005, 02:03 PM']Thanks for the Reply Mark. Does the Baffle reduce oil slosh by eliminating the free space that is normally between the oil and the block?



I am concerned about reducing the capacity. Hopefully I can make up for the drop in capacity with two large oil coolers. You're right I could also expand the pan laterally.



I agree, $500 is conservative. However, given the way things are going it wouldn't surprise me if it cost 2x as much.


[/quote]

It doesn't eliminate the free space, just under hard cornering etc. it stops it sloshing past it - in the picture I posted if the plate wasn't there all the oil would be free to slosh all the way up the engine.



Someone who's able to weld shouldn't have any problems with it if you know what you want.



Mark

[quote name='ccarlisi' date='Jun 1 2005, 09:03 AM']Thanks for the Reply Mark. Does the Baffle reduce oil slosh by eliminating the free space that is normally between the oil and the block?




[/quote]



The baffle keeps the oil near the pickup at all times so you aren't sucking air.

[quote name='93 R1' date='Jun 1 2005, 12:03 PM']The baffle keeps the oil near the pickup at all times so you aren't sucking air.


[/quote]



Justin, I know what a baffle is for. I am trying to figure out how it works -which I believe I also understand, but want verification.



Thanks,



Chris.

Here is a picture of the RX8 pickup (ignore the red circle). Notice how far foward it sits in the pan.

I'd put the engine in the car the way you want it and then worry about ground clearance first. Measure it all out and then make the pan as big as you can. Large oil coolers will also help some with upping the oil capacity.

[quote name='Dragon' date='Jun 30 2005, 10:45 PM']I'd put the engine in the car the way you want it and then worry about ground clearance first. Measure it all out and then make the pan as big as you can. Large oil coolers will also help some with upping the oil capacity.


[/quote]



The lower the motor is the less cutting I have to do to the firewall and transmission tunnel https://www.nopistons.com/forums/pub...IR#>/blink.png .

[quote name='ccarlisi' date='Jul 1 2005, 03:44 AM']The lower the motor is the less cutting I have to do to the firewall and transmission tunnel https://www.nopistons.com/forums/pub...IR#>/blink.png .


[/quote]



Let me reword my post since I was in a hurry last time... First put the engine in the car the way you want to mount it... I.e. As low as your planning on going with it. Then drop the car down and see how deep you can make the pan and still keep enough ground clearance that you’re not going to rip it off the car over some shitty manhole cover or speed bumps. I'd worry about the following things in the following order...



1. Ground clearance of the pan.

2. Capacity

3. Baffling to eliminate air bubbles in the oil.

4. Structural integrity to reinforce the engine.



When you fill the oil pan up to the dipstick full line the oil level is actually above the pan and in to the engine a little bit. This is why FD's leak oil from the rear mounts even when the car isn't running until the oil level drops below the top of the oil pan... For this reason I wouldn't really worry too much about sucking air from hard cornering etc because the pan will stay quite full all the time so there isn't a lot of room for the oil to slosh around.

[quote name='Dragon' date='Jul 1 2005, 07:48 AM']Let me reword my post since I was in a hurry last time... First put the engine in the car the way you want to mount it... I.e. As low as your planning on going with it. Then drop the car down and see how deep you can make the pan and still keep enough ground clearance that you’re not going to rip it off the car over some shitty manhole cover or speed bumps. I'd worry about the following things in the following order...



1. Ground clearance of the pan.

2. Capacity

3. Baffling to eliminate air bubbles in the oil.

4. Structural integrity to reinforce the engine.




[/quote]



We're on and have been on the same page.



The goal is: Drop the height of the motor as much as possible



The limiting factors are:

(1) 5" of ground clearance

(2) The pan must be adaquate for track events.



I'm not concerned about the capacity of the pan because I am going to have more than enough in the lines and coolers, and can use a reserve if necessary.



Very good point. Thanks.

Having sad everything I've said, if that was my car I'd probably still end up dry sumping it. My opinion on these things is that you should spend a proportionate amount of the overall cost on engine safety - i.e. on a more expensive engine you spend more to make sure it doesn't go pop.



You should be able to install a dry sump system for about $1500, less if you're prepeared to do some of the work yourself - I'd imagine bespoke 20b kits are quite expensive, but if you buy the pump, plumbing and reservoir off the shelf, all you're left with is the sump, which if you can't find one cheap enough the only complications with making one are the scavenge inlets and these are just simple fittings for the pipes.



The advantages of dry-sumping I'm sure you know, the biggest being the peace of mind when you're taking those high speed corners on the track.



Mark