Oil Pan Mystery

[serafins]

Got an interesting one for the viper brain trust.

I have this pan off my '99 ACR. By all external indications, it is the short pan for the 8.5qt oil system (2 rib, early internal bosses, fastener holes bump out the side of the pan lip). I have the correct dipstick and tube for a '99.

However, my car has always taken 10qts of oil to read "full" on the dipstick. I just pulled the pan off to send to Exotic Engines to have it fitted for their external oil pump kit. While off I measured the depth of the pan. It is 3.75" in depth, measured from the screen over the oil pickup to the pan rail.

@GTS Dean was nice enough to measure his "10qt" pan. It measured 4" from the same spot.

Based on the rough volume of the pans, mine holds about 6-7% less oil than the "10qt" pan. This would mean my system (filter, cooler, pan) holds about 9.5 quarts. So while it has the external appearance of an 8.5qt pan, it is deeper and holds about 1qt more oil.

Anyone seen such a pan before? It's the first one I've seen that is a "C" revision part number. My only thought is it was sold aftermarket through Mopar in '99 with the "ACR+" line of parts, since they did list an upgraded oil pan as being available.

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[GTS Dean]

Just to confirm - were your measurements from the gasket flange (pictured above) down to the screen?

My measurement was ON THE CAR, from the underside of the flange, to the external bottom of the center sump casting (driver's side). An eighth here, an eighth there can make a volume difference with as much square inch x depth as the sumps have. For reference - this is the OE 8qt pan.

 

[serafins]

Just to confirm - were your measurements from the gasket flange (pictured above) down to the screen?

My measurement was ON THE CAR, from the underside of the flange, to the external bottom of the center sump casting (driver's side). An eighth here, an eighth there can make a volume difference with as much square inch x depth as the sumps have. For reference - this is the OE 8qt pan.

In the pan. But another guy sent me pics of his 10qt measured the same way mine was measured and it was also 4in exactly. This was his pan:

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[Goggles Pizano]

It is the rest of the world (non-US) metric pan.

 

[99RT10GTS]

it's the 8.5, but it won't hurt anything if you add an extra qt. I am betting someone dicked with your dipstick

 

[Dan Cragin]

I've only been aware of the early and late Gen 2 oil pan. The later started with the ACR and carried on from there. I think there was only
one dipstick and tube for each, so most likely your pan pan is not unique, but who knows.

One thing you have to be very aware of with that external oil pump system on the Gen 2 is that you can easily wet sump the motor and run
out of oil at high rpm at the track if you don't keep the oil level up. I run an extra quart and mark the dipstick to reflect that. Windage is typically
not an issue. Better safe than sorry.

 

[GTS Dean]

Dan, That's an interesting comment. Hopefully the shop that is packaging this has plenty of experience with it. Determining the proper pump rotor length and pulley drive ratio for the amount of WOT time the build will see at its heaviest track loading is critical.

 

[Dan Cragin]

I’ve used these many times. It’s just critical not to run low on oil as you do only have what is in the oil pan and these pumps are typically used with a dry sump system.

 

[serafins]

Thanks for the feedback Dan. Always appreciated from you. Exotic Engines is putting the kit together. As I understand it this is what they run on their 7krpm+ packages and I have spoken to a few former customers that run their gen 2 up to 7k rpm with this setup without issues. But I will be sure to keep the pan overfilled too.

 

[serafins]

it's the 8.5, but it won't hurt anything if you add an extra qt. I am betting someone dicked with your dipstick

So do we think the "10qt" pan really doesn't add an extra quart and a half of oil but maybe .5qt and the other 1qt is attributable to the factory telling people to "overfill" their pan?

The disptick is totally stock. Dean posted pics of the 2 different Gen 2 dipsticks and retainers and mine is very clearly the early dipstick AND retainer. So there is extra capacity in the system somewhere. Maybe the oil cooler. I haven't really checked that out yet to see if it's original.

 

[Dan Cragin]

I've used Kevin's setup at EED and its a great alternative to a dry sump system.

 

[GTS Dean]

To be clear about the dipsticks and tubes - the longer pair are for the 8qt '96-97 Gen2 blocks. Properly paired, both combinations will put the "FULL" mark at the top of the steel sump cover. The cover is attached at exactly the same depth from the pan rail regardless of pan capacity. Adding a quart over full will put oil on top that plate at startup. When running with crank windage and top end accumulation, that quart is pulled below the plate.

 

[serafins]

To be clear about the dipsticks and tubes - the longer pair are for the 8qt '96-97 Gen2 blocks. Properly paired, both combinations will put the "FULL" mark at the top of the steel sump cover. The cover is attached at exactly the same depth from the pan rail regardless of pan capacity. Adding a quart over full will put oil on top that plate at startup. When running with crank windage and top end accumulation, that quart is pulled below the plate.

Yes. I have both the short dipstick and short tube. So something is holding extra capacity over a "stock" 8.5qt system. Be it the pan as I suspect or maybe the cooler.

 

[GTS Dean]

I'll try to get to my OE pan to measure the sump depth and compare with yours. There were some running changes to the cooler over the years. I found an old VCA thread where 'Tom F&LGR' measured pressure drop across an older and newer unit and it was a noticeable improvement

 

[GTS Dean]

I measured my standard (RevA) pan and it is 3.5" from gasket flange to inlet screen. It is actually the second of 3 pans on my engine. There were an early batch of 96 GTS cars that had casting porosity issues and Dodge sent the Rev A warranty pans out for install.

 

[serafins]

Thanks to Dean’s sleuthing we have now confirmed that the “Rev C” pan is different than both the “Rev A” pan and the 10qt “AB” pan.

Rev A is 3.5 inches deep.
Rev C is 3.75 inches deep.
AB is just shy of 4” deep.

So the rev C is a transitional design at least used on some ‘99 ACRs since my car was built in Feb ‘99.

And since all the other dimensions of the pans are the same, and we know the AB pan holds 10qts, and the Rev A pan holds 8.5 qts, the vertical dimension on the Rev C being exactly halfway between those two pans means the capacity of the Rev C is also right in the middle at 9.25qts.

 

[serafins]

I ordered a copy of the 1999 mopar performance catalog off eBay. It arrived last night. On the second page it lists an “increased capacity” oil pan and says it’s standard equipment on the ACR. Forgot to snap a pic but I’ll get one tonight.

So I am now 100% sure at least some 99 ACRs got this increased capacity pan before the general switch to the 10qt pan in 2000. Meaning I probably just sent a 1 of xx pan to Kevin to get chopped up for the external wet sump kit. good thing the early mopar muscle car purists didn’t migrate to the viper world or they’d have my head on a pike.

 

[GTS Dean]

Most 'Mopar purists' never ran their cars like Viper owners. We are more like those few guys who flogged the crap out of their Hemi and 6-Pack cars.

 

[BoondocSaint]

I'll definitely be paying closer attention when I do my next oil change. Normally I just fill until it's good, but now I want to know which pan that good corresponds to lol.

 

[serafins]

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[BoondocSaint]

What was the trap door that came in these pans? I've seen aftermarket ones that are supposed to help with g-loading oil starvation, always planned to pick some up and install them. Are these ones a similar design to the aftermarket? My 99 ACR was built in May, really has me wondering if I have a pan that was set up better than I knew.

 

[GTS Dean]

There were never any trap doors from the factory in Gen 1,2 or Gen 3 cars. G4 & 5? - no idea. The swinging gates are all aftermarket. I never thought the open top/with lips idea was worth a darn. Oil can still slosh up the side walls under heavy cornering, or spill over the short dams fore-aft. I'd rather keep the factory single opening plate directly above the central chamber because all the drain-back HAS to go right into the most important area. IMO, best would be either the plate with 1 rectangular and 2 additional square holes; or multiple dimpled holes over the front and rear chambers which I did.

 

[serafins]

Yep Dean is correct that the top plate shown and trap doors were not installed on a production car from what I can tell. I had a mopar parts vendor look up the part number on their system and they did not show it coming with a top plate. I think that pic just shows a cutaway of the normal top plate so you can see the trap doors. Not sure about the windage tray. I'll have to check mine this weekend to see if it's any different than the normal one.

 

[serafins]

This was the top plate on mine. still had the factory gasket so I don't think it had ever been opened up before.

Note all the oil just sitting on the top plate even after dropping the pan. Terrible design for oil return. It's getting replaced with the Ipsco top tray and gates.

Combined with the dinky square cast-in pickup tube (which had to be more expensive than just running a normal stamped steel tube), I have to wonder what the engineers were thinking here. Don't even get me started on the tiny gerotor in the stock oil pump. The stock oil system could have been perfectly fine at high rpm had they just stuck with a round pickup tube and increased the gerotor diameter.

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[GTS Dean]

The windage tray was changed in 99 or 00, possibly on all cars IIRC. The obvious difference are scalloped drain channels instead of straight drains nearer the block skirt. These scallops have more edge length to help break larger bubbles in aerated oil.