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Old 02-07-2018, 06:57 PM   #1
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3.4 swap in track car - Motorsports AOS fitment issue

Hi all,

I did a 3.4L engine swap last year on my 986 (1999 3.4L into my 1999 986) and I recently discovered at my first test day (Big Willow in SoCal) that the car suffers from the dreaded white smoke plume after high-g turns (T2 & T8/9). I was black flagged after only 3 laps and my day was done before I could even get heat into the Nitto NT-01s.

The car went back to my trusted mechanic and I did extensive research on the topic. After hours of reading, I ordered the 0.5 qt LN sump extension, X-51 baffle, 997 oil return tubes, and the motorsports AOS. I opted to go with the smaller sump extension since the 3.4L engine already sits 1" lower than the original 2.5L due to the spacers required for the 3.4L intake stack to fit in the engine bay. I don't have the space below the car for the 2qt sump to hang an additional 1" below the already-low 3.4L.



Now that all the parts have arrived and the installations have begun, my mechanic is telling me that the motorsports AOS will not fit for two reasons:

First, the 3.4L 996 engines have a differently shaped AOS than the 3.6 engines so they are not plug and play. My understanding is that custom hoses must be made in order for this to fit.

Second, even if the custom hoses could be made, when the intake is rotated 180 degrees (as is required on the 996 engine to fit the 986 intake layout), there is no longer space to install the larger motorsports AOS.




Does anyone have any advice or experience dealing with this motorsports AOS issue on the 3.4L 996 engine when installed in a 986? Or are there any other ideas I'm missing?

Lastly, if anyone from SoCal is going, I will be up at Willow again this Friday with POC to dyno the car for GT classification.


Thank You all in advance.


Regards,

Marc Jannone
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Old 02-08-2018, 10:05 AM   #2
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Hi Marc, I have an extra Mantis 1.2 L deep sump for $400 (I bought to compare with my 2L LN deep sump but then I lost my enthusiasm for tinkering ) that barely hangs down any further than the OEM oil pan bottom, you may be able to stack that with your .5 extension to get 1.2L + .5 of extra oil (or replace the .5 spacer), and then run the oil around halfway between the high and low tick marks on the digital gauge. I run the 2L LN deep sump and run my oil like that and don't have any trouble anymore with smoke bombs. And I have discovered if I run the oil higher, it quickly is depleted down to around that halfway point, I guess due to oil ingestion? But thankfully not enough to make a smoke bomb.
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Old 02-24-2018, 10:31 AM   #3
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Quote:
Originally Posted by mjannone View Post
Hi all,

I did a 3.4L engine swap last year on my 986 (1999 3.4L into my 1999 986) and I recently discovered at my first test day (Big Willow in SoCal) that the car suffers from the dreaded white smoke plume after high-g turns (T2 & T8/9). I was black flagged after only 3 laps and my day was done before I could even get heat into the Nitto NT-01s.

The car went back to my trusted mechanic and I did extensive research on the topic. After hours of reading, I ordered the 0.5 qt LN sump extension, X-51 baffle, 997 oil return tubes, and the motorsports AOS. I opted to go with the smaller sump extension since the 3.4L engine already sits 1" lower than the original 2.5L due to the spacers required for the 3.4L intake stack to fit in the engine bay. I don't have the space below the car for the 2qt sump to hang an additional 1" below the already-low 3.4L.



Now that all the parts have arrived and the installations have begun, my mechanic is telling me that the motorsports AOS will not fit for two reasons:

First, the 3.4L 996 engines have a differently shaped AOS than the 3.6 engines so they are not plug and play. My understanding is that custom hoses must be made in order for this to fit.

Second, even if the custom hoses could be made, when the intake is rotated 180 degrees (as is required on the 996 engine to fit the 986 intake layout), there is no longer space to install the larger motorsports AOS.




Does anyone have any advice or experience dealing with this motorsports AOS issue on the 3.4L 996 engine when installed in a 986? Or are there any other ideas I'm missing?

Lastly, if anyone from SoCal is going, I will be up at Willow again this Friday with POC to dyno the car for GT classification.


Thank You all in advance.


Regards,

Marc Jannone


It's possible to do it. Have to make an adapter. I had made one for myself about ten years ago and someone called about two weeks asking for one. I pulled my original one and we updated the design and made a handful of them. If you have access to a machine shop, anything is possible :-) Hoses still are a challenge - but that just requires you to be creative.

If you run the oil at the min level and use a race oil, that will help reduce the load on the AOS as well.
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