3.6 converters to early cars - anyone run factory air cleaner box?

DW SD · 12-01-2009, 07:58 AM

Guys,
I was at the local PCA autocross the other day and my car is too loud. I'm wanting to take steps to quiet things down. I have some inserts for the exhausts coming and I believe the cone air filters are known to be louder than the factory air box.

I have a '95 993 engine in an '71 tub. Can anyone say for certain that the factory air box will fit? I have another Pelican who offered to sell me the '95 airbox for a good deal, but thought I'd try to determine if it would fit, first.

Does anyone have unobstructed pictures of the '95 factory air box on the '95 engine?

Thank you,

Doug

Steve@Rennsport · 12-01-2009, 08:40 AM

Doug,

The factory airbox will fit, but you will need to do some modifications on the cover to clear the deck lid hinge.

DW SD · 12-01-2009, 08:57 AM

Quote:

Originally Posted by Steve@Rennsport

Doug,

The factory airbox will fit, but you will need to do some modifications on the cover to clear the deck lid hinge.

Steve,
Excellent! Do you think this will mitigate some of the noise from my setup? Wild-assed guess would be fine

I'm trying to get down from 97dbs to 93dbs. This is measured tangentially on a straightaway with calibrated gear, 50' from the edge of the track.

I have considered gluing egg crate sound absorbing foam on the inside of the FG engine lid, too.

I will install the car chemistry inserts into the exhaust, when they arrive. Between the two, I'd hope for a decent reduction.

Thank you,

Doug

Bill Verburg · Bill Verburg's Garage

Quote:

Does anyone have unobstructed pictures of the '95 factory air box on the '95 engine?

Here's mine when I had a 964 engine in it, it's externally pretty much the same as a '95 993

PcarPhil · 12-01-2009, 09:10 AM

Doug,

I'm thinking along the same lines as you are!

3.6 conversions - use stock 3.6 airbox?

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by Kaefer

Doug,

I'm thinking along the same lines as you are!

3.6 conversions - use stock 3.6 airbox?

Those are mine, the cut away one was needed to fit the 993RS vram motor into my '76, the other is a stock 993 vram Motorsound cover

DW SD · 12-01-2009, 09:35 AM

Thank you all for your replies!

Bill,
Can you confirm any noticeable difference in noise with the factory airbox? I realize this is quite subjective. Then again, your current setup is very close to mine.

thank you,

Doug

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by DW SD

Thank you all for your replies!

Bill,
Can you confirm any noticeable difference in noise with the factory airbox? I realize this is quite subjective. Then again, your current setup is very close to mine.

thank you,

Doug

The stock cover has a small but definite effect on reducing noise. I carry one to restricted events, just in case

Steve@Rennsport · 12-01-2009, 09:44 AM

Quote:

Originally Posted by DW SD

Steve,
Excellent! Do you think this will mitigate some of the noise from my setup? Wild-assed guess would be fine

I'm trying to get down from 97dbs to 93dbs. This is measured tangentially on a straightaway with calibrated gear, 50' from the edge of the track.

I have considered gluing egg crate sound absorbing foam on the inside of the FG engine lid, too.

I will install the car chemistry inserts into the exhaust, when they arrive. Between the two, I'd hope for a decent reduction.

Thank you,

Doug

Doug,

A 4db reduction is a LOT,.................SPL scales are logarithmic, not linear.

Without any detailed information about your current exhaust, its very tough to speculate about where the biggest reductions may be found, but the stock airbox and cover is much quieter than the cone filter you currently use. The stock airbox makes more power, too (with an open cover).

Mahler9th · 12-01-2009, 10:20 AM

Are you sure your cone filter is contributing to your excessive sound? What type of exhaust do you run?

My car has a 3.8L run with Haltech, and runs a cone filter. The exhaust system is S Car Go headers mated to some Phase 9-type mufflers. It is very loud, but when I add a large secondary muffler, I can run at Laguna Seca and make 92 dB with no power loss. The cone filter does not contribute enough noise to be an issue. This may also be the case with your set up.

The airbox that was in the car when I bought it is shown below. It is a modified '95 airbox, with an aluminum intake snorkel to get air from right under the deck lid, which in my case is a 993 3.8 style unit. I am not sure whether the snorkel would fit under a stock type deck lid... but it could probably be modified if it doesn't. I think the potential advantage of this modied airbox is that it should get cooler air. It is sitting on a shelf in my shop (it is for sale if anyone can use it).

My current set up is a cone filter housed in a custom carbon fiber box I made in an attempt to get colder air in. Works well.

Modified '95 airbox:

PcarPhil · 02-03-2010, 05:45 AM

Hey there Doug,

I'm curious if you've tried to fit a stock '95 airbox to your engine yet, and if so does it fit in your car using the 3.2 Carrera engine support (no spacers to lower the engine?)?

My '95 3.6 is coming along. I've currently got a stock airbox attached to the engine, have the 3.2 engine carrier installed, and continue to work on all the small details. I just don't see how the stock airbox will fit in the engine bay without lowering the engine using spacers. Or if it does it's going to be a super tight fit up against the rear parcel shelf.

Thanks for the help!

DW SD · 02-03-2010, 06:47 AM

Fellas,
I run the M&K dual outlet exhaust as seen here. I have not added a factory airbox, yet. My engine is spaced about 1/2" down for more clearance. I did create a bubble in the rear parcel shelf for clearance, yet the top of the rubber air intake touches the parcel shelf. The top for me, is a rubber hoop which retains the IAC motor.

Scott, does the factory air filter housing sit higher than the rubber elbow which is between the throttle and the intake manifold? If so, then I think clearance may be an issue.

PcarPhil · 02-03-2010, 07:14 AM

Quote:

Originally Posted by DW SD

Scott, does the factory air filter housing sit higher than the rubber elbow which is between the throttle and the intake manifold? If so, then I think clearance may be an issue.

This is the only pic I have at the moment. From memory I think the top of the air filter housing is about level (or just under) with the rubber hoop which retains the IAC motor.

PcarPhil · 02-03-2010, 07:57 AM

Here's a better pic:

PcarPhil · 02-05-2010, 07:41 AM

So Doug...do you think based on my pics above that a stock '95 airbox will work in your car (or mine)?

As always...thanks for the help!

jevvy · 02-05-2010, 08:01 AM

I've tried fitting a stock airbox on my 3.6 NVR conversion and couldnt get it to clear the hinge without cutting the cover up or using longer spacers for the engine neither of which I fancied at the time. Having seen some of the modified airboxes above I might give it another go armed with a dremmel.

Height wise I think its ok, its just the hinge getting in the way.

PcarPhil · 02-05-2010, 08:16 AM

I've thought about switching to 911R style hinges to alleviate the width issue. Either that or a dremel (but that would negate part of the reason for using the airbox - reduced volume).

I'm mostly wondering about the height issue. I don't think a stock 3.6 airbox will clear without using 1" or so spacers for the engine carrier.

arrivederci · 02-05-2010, 08:26 AM

I'm toying with the same thing. My '96 motor has a motorsound airbox...will know better in about 2 months when I'm trial fitting the motor before I go in for paint. I'm replacing the parcel shelf (rust), which provide some opportunity to slightly modify for a better fit.

DW SD · 08:59 AM

Scott,
I should have my '95 airbox in hand within a few days and will let you know. Anything else will just be a guess. I'm pretty sure the box lid will have to be cut to clear the hinge, per Steve Weiner.

Josh,
If you have a chance to build in more clearance, I would definitely do so!

If you lower the engine too much in the chassis, the 3.6 hangs below the bodywork, at least with the pre-'74 bumper. Looks funny from the side. My car is already very low, so I am balancing clearance at the window shelf vs. the engine hanging out the bottom.

Doug

mnmasotto · mnmasotto's Garage

I have a similar engine setup but in a 1987 body. I had to used 3/4" spacers at the cross brace to get this setup to work. Also, I had to basically cut off the majority of the cover to get any workable room around the air box. In my humble opinion, your main problem is your exhaust. I have went through four iterations of exhaust setups on my 3.6L transplant and have finally found a system that is as quiet as the complete stock 993 setup. The power is almost the same as my S-Car-Go headers.
P.S. Forget about the header inserts you lwill loose too much power. I noticed a big difference in performance once I removed mine. The sound deadening was great but the power loss was not so good.