That is a good idea. I might have to look into it as well.

This weekend I took the filter back out of the car and removed the filter element from it's housing. Then I applied rubber undercoating to the exterior of the housing. As best as I can tell it improved the appearance as well as lowered the db's. Not a whole lot of db reduction, but it was noticeable especially at half throttle. I had also thought about doing the same to the pipe, and after reading your reply it sounds like that might be a good idea. Besides part of the fun is messing with the car, right.

 

Mine got a bit quiter after I did the idle re-learn.

The stock intake isn't bad the way it is actually. And, you could always just drop a K&N filter in the stock intake too. If your crusing on the highway it really shoudln't drone unless your ON the throttle. Mines only loud when I get on it.

 

WOT + SRI = loud

No way around it

 

What are the procedures to do this?

 

I had put my intake up for sale as I didn't care for the loudness of the sound, but with little interest I decided to try and make it more to my taste.

I started off with spraying Duplicolor Undercoating on the plastic intake housing like RUFit did (I think we even did it the same weekend, lol) and I too noticed a slight decrease in sound.



Liking the results, I searched for a material that would provide even more sound deadening. In the end, I found this:



DEI Boom Mat Spray. With little in the way of user reviews available, I decide to order some and try it out, since it was claimed to provide solid sound deadening and thermal insulation.

I sprayed it over the rubber undercoating on the filter element housing, as well as on the metal tube (after careful masking of course!). It's similar to the undercoating, but when felt there seems to be heavy, almost metallic like particles suspended within it.







Visually, I like it quite a bit as I've never cared for shiny add on pieces under the engine bay. More importantly however, I think I've managed to get exactly what I wanted.

Sound wise the intake is barely louder than stock up to some 3/4 throttle and less than 4,000 or so RPMs. It doesn't drone, and the tone is much more "grown up." Additionally, the top end wail is purer, the added material seeming to have removed the slight buzz I was getting at high engine speeds. It still sounds wonderful at high revs.

The thermal insulation claim seems to be fairly accurate as well. Normally, on a hot today like today, like most SRI setups, the throttle pickup gets softer. Today though, the performance of the car seemed much more consistent even when crawling in hot, stop and go traffic.

All-in-all, I'm now very satisfied with my setup, as it seems to provide a mellow,barely audile tone when cruising (quieter than stock in fact), a meatier tone when accelerating gingerly, and even better wail at full throttle.

Throttle response is comparable at stock at more normal engine speeds, and much better in the higher rev ranges.

 

Excellent write up, nice job! +1

 

That is a great write up and sounds like something I am going to try since the intake is now out of the car and sitting in the garage. My gas mileage seemed to go down quite a bit as well, with the same style of driving, which is another reason I put it back to stock. Come to find out it must have been the increase in temperature outside that was lowering the gas mileage because stock is the same mpg. Guess I have a new weekend project, because I do miss the performance increase.

 

Great post reako. Thanks for sharing.

 

pilosopo I was wondering if you have checked the filter after driving for awhile to see if the coating is being affected by the heat. I found that it is good for up to 300 F, and I am not sure how hot it gets under the hood.

 

Pssssst...give credit where credit is due....to pilosopo! He be the one who posted the DIY (not that Reako is a bad guy or anything )

 

DUH, Thank you pilosopo. I knew I should have had another cup of coffee this morning.

 

if u think thats loud try open headers

 

Funny enough, I wanted to make my PRM work because my mileage has consistently been better when compared to the stock intake.

I just want to make sure you understand the intake can still get quite load. On the freeway, light loads, light acceleration, IMHO, it is now quieter than stock.

Accelerating more heavily, up hills, passing, etc. is still louder than stock, it's just a more grown up, meatier sound now, as though much of the second order stuff has diminished. It's not that much louder though, as passengers I've had, including my grandmother who drives a Lexus, didn't even notice or car.

Wide open throttle is still really loud, but again, the tone and quality of the sound is better.

I also replaced the worm drive clamps with high torque t-bolt clamps, and it again seems to have helped. T-bolts clamps camp more uniformly, and because you can clamp tighter, it seems to make everything work better.

It seems to have finally killed this annoying buzz I had when the car really got on cam.

I've been checking up on everything, and it all seems okay. I don't have any temp sensors or anything hooked up, but the coating is holding up fine.

I do like however, that after a long, spirited drive, I can hold the metal part of the intake and it's merely warm, as opposed to scalding hot before being coated. So in my estimation, it's reflecting a lot of radiant heat. And really, in my case, the car seems to running much better, especially in the heat.

 

If you think that's loud, have you ever heard the same on a rotary, like an RX-7... I'll be damned if that isn't the loudest motor (in terms of pure volume) sound I've ever heard.