Community Forums

skitime · 06-14-2006, 04:08 PM

Yet another DIY Cold Air Intake that is different than the rest.

I have been reading with great interest posts on cold air intakes for the Workhorse chassis. You do have to give Workhorse some credit because they did build a cold air intake system to start with. My last motorhome did not have one. I understand why Workhorse designed their cold air intake system the way they did but it is woefully flawed. Workhorse had to build an intake system that would not interfere with any RV bodies the RV manufactures would build on it. They would not know the clearances for different doghouses built by different manufactures. This is why they could not go the obvious route for an air intake system directly from the grill area to the throttle body. The air intake shortcomings have been discussed by many forum members who have talked about the unbelievable length of the air intake system which is almost 7' long. In this design there are many hard turns and constantly changing sizes. The tuba inlet begins the air flow at 5 ½ inches. The inlet tube for the air cleaner is down to 4 inches. The tube leaving the air cleaner is down to 3 inches. Before the air enters the throttle body it returns to 4 inches. Here are photos of my original complete system. You can see for yourself what a mess the system is.

Front View

Right Side View

Left Side View

4" Throttle Body Connection

Last Turn Before Throttle Body

120 Degree Turn After The Throttle Body

4" Entrance To Air Cleaner Housing

The DIY and commercial modified cold air intakes all address one major shortcoming of the Workhorse design which results in increased horsepower and better fuel economy. This flaw is the connection between the air cleaner and the mass air flow sensor. The air leaves the air cleaner body through an oval opening and flows immediately into a round air flow sensor. This connection is an unbelievably bad mismatch. How Workhorse designed this part is a mystery and the engineer that did should be fired. Every Workhorse 8.1 owner should at the very least change this major bottleneck. It is simply a must do. Anything you replace it with will be better than what is there. This major bottleneck that leaves the mass air flow sensor only partially being used and the engine starving for air. Here is a picture looking from the air cleaner housing at the mass air flow sensor. You can see how poor this design is.

Here is a picture from the back with the air flow sensor removed so you can see how much of the mass air flow sensor would be blocked.

Here is a picture of the mass air flow sensor removed. You can seen how by the dirt on the sensor how much is blocked. I had smudged some of the dirt off already but you can see the shape of the pattern anyway.

Even if you address the mismatch of the MAF sensor and the air cleaner opening there are still some other weaknesses in the Workhorse intake that I wanted to address on my motorhome. After the MAF sensor the air intake makes a 120 degree turn and is now a small 3 inch tube making several more hard turns before changing to a 4 inches connection prior to the throttle body. I built an improved simplified system that addresses the rest of the shortcomings of length of system, turns, and restrictions. Since I have a Trail-Lite P32 Class A motorhome I am not sure what I have done will be applicable to other Workhorse Class A RVs but I would think it would probably work perhaps with some slight modifications.
My design utilizes the factory Workhorse air filter and housing. The original filter and housing is more than adequate if the oval restriction is removed and outlet is enlarged. The original Workhorse filter is also used on high performance Corvettes which run at much higher RPMs than the 8.1 liter engine does and the filter is more than adequate for the Corvette. I could replace the paper filter with a K&N type filter that will fit this housing but prefer the inexpensive easily replaced disposable paper filter. I modified the air cleaner outlet by using the original 4 inch air filter inlet piece. The back of the filter housing was modified to accept the piece. It was then adhered to the housing using urethane windshield adhesive.

View Towards Radiator

View Towards Front

Top View

Bottom View

Installed View

View Through Hood

The inlet side was modified to accept the original tuba wire guard. The wire guard was also adhered using the urethane windshield adhesive. I used the original rubber mounts to mount the housing to a steel cross support above the radiator. The rubber mounts prevent the housing from being cracked by the mounting bolts. This setup allow for easy filter inspections by just looking through the wire guard. The filter is now easily replaced by opening the three original clips. The MAF sensor can also easily be inspected by removing the air filter. If you need more room to work under the hood, the air filter housing can be easily removed to make clearance. The plug for the MAF sensor was rerouted to the new location and was plenty long enough to do this without splicing. By using the original parts, the only piece I had to buy was the 4" S shaped rubber tube between the MAF sensor and the throttle body. I made a steel piece to block off the large hole in the wheel well that remained after removing the original air cleaner parts. I believe this cold air intake system has addressed all the Workhorse shortcomings, reduced weight and should work better. It is less then 36 inches in total length including the S bend. It also has simplified maintenance and retained the inexpensive and easily obtained original air filters.
The motorhome seems quicker but I will not know if I get any gas mileage improvement till we go on a trip in a few weeks. Noise is louder at full throttle but I will be building a noise baffle in the air cleaner housing when I get time.

skitime · 06-14-2006, 04:08 PM

Yet another DIY Cold Air Intake that is different than the rest.

I have been reading with great interest posts on cold air intakes for the Workhorse chassis. You do have to give Workhorse some credit because they did build a cold air intake system to start with. My last motorhome did not have one. I understand why Workhorse designed their cold air intake system the way they did but it is woefully flawed. Workhorse had to build an intake system that would not interfere with any RV bodies the RV manufactures would build on it. They would not know the clearances for different doghouses built by different manufactures. This is why they could not go the obvious route for an air intake system directly from the grill area to the throttle body. The air intake shortcomings have been discussed by many forum members who have talked about the unbelievable length of the air intake system which is almost 7' long. In this design there are many hard turns and constantly changing sizes. The tuba inlet begins the air flow at 5 ½ inches. The inlet tube for the air cleaner is down to 4 inches. The tube leaving the air cleaner is down to 3 inches. Before the air enters the throttle body it returns to 4 inches. Here are photos of my original complete system. You can see for yourself what a mess the system is.

Front View

Right Side View

Left Side View

4" Throttle Body Connection

Last Turn Before Throttle Body

120 Degree Turn After The Throttle Body

4" Entrance To Air Cleaner Housing

The DIY and commercial modified cold air intakes all address one major shortcoming of the Workhorse design which results in increased horsepower and better fuel economy. This flaw is the connection between the air cleaner and the mass air flow sensor. The air leaves the air cleaner body through an oval opening and flows immediately into a round air flow sensor. This connection is an unbelievably bad mismatch. How Workhorse designed this part is a mystery and the engineer that did should be fired. Every Workhorse 8.1 owner should at the very least change this major bottleneck. It is simply a must do. Anything you replace it with will be better than what is there. This major bottleneck that leaves the mass air flow sensor only partially being used and the engine starving for air. Here is a picture looking from the air cleaner housing at the mass air flow sensor. You can see how poor this design is.

Here is a picture from the back with the air flow sensor removed so you can see how much of the mass air flow sensor would be blocked.

Here is a picture of the mass air flow sensor removed. You can seen how by the dirt on the sensor how much is blocked. I had smudged some of the dirt off already but you can see the shape of the pattern anyway.

Even if you address the mismatch of the MAF sensor and the air cleaner opening there are still some other weaknesses in the Workhorse intake that I wanted to address on my motorhome. After the MAF sensor the air intake makes a 120 degree turn and is now a small 3 inch tube making several more hard turns before changing to a 4 inches connection prior to the throttle body. I built an improved simplified system that addresses the rest of the shortcomings of length of system, turns, and restrictions. Since I have a Trail-Lite P32 Class A motorhome I am not sure what I have done will be applicable to other Workhorse Class A RVs but I would think it would probably work perhaps with some slight modifications.
My design utilizes the factory Workhorse air filter and housing. The original filter and housing is more than adequate if the oval restriction is removed and outlet is enlarged. The original Workhorse filter is also used on high performance Corvettes which run at much higher RPMs than the 8.1 liter engine does and the filter is more than adequate for the Corvette. I could replace the paper filter with a K&N type filter that will fit this housing but prefer the inexpensive easily replaced disposable paper filter. I modified the air cleaner outlet by using the original 4 inch air filter inlet piece. The back of the filter housing was modified to accept the piece. It was then adhered to the housing using urethane windshield adhesive.

View Towards Radiator

View Towards Front

Top View

Bottom View

Installed View

View Through Hood

The inlet side was modified to accept the original tuba wire guard. The wire guard was also adhered using the urethane windshield adhesive. I used the original rubber mounts to mount the housing to a steel cross support above the radiator. The rubber mounts prevent the housing from being cracked by the mounting bolts. This setup allow for easy filter inspections by just looking through the wire guard. The filter is now easily replaced by opening the three original clips. The MAF sensor can also easily be inspected by removing the air filter. If you need more room to work under the hood, the air filter housing can be easily removed to make clearance. The plug for the MAF sensor was rerouted to the new location and was plenty long enough to do this without splicing. By using the original parts, the only piece I had to buy was the 4" S shaped rubber tube between the MAF sensor and the throttle body. I made a steel piece to block off the large hole in the wheel well that remained after removing the original air cleaner parts. I believe this cold air intake system has addressed all the Workhorse shortcomings, reduced weight and should work better. It is less then 36 inches in total length including the S bend. It also has simplified maintenance and retained the inexpensive and easily obtained original air filters.
The motorhome seems quicker but I will not know if I get any gas mileage improvement till we go on a trip in a few weeks. Noise is louder at full throttle but I will be building a noise baffle in the air cleaner housing when I get time.

Jestme13 · 06-14-2006, 04:29 PM

Nice idea, looks like a nice KISS system. Is the noise that bad that a restrictive baffle needs to be used. I think that sitting directly over the radiator will cause it to swallow more hot air then if it were off to the side, behind a head light. Again, NICE JOB,

rogueii · 06-14-2006, 04:56 PM

Nice Job!!!
I have all my air system sitting on the floor. I will be getting my Reducer for the MAF to 4 '' tommorow and will install a 9" long (High Performance) S&B Inverted Cone filter in a can that is 8" in Dia.. I will use a 6" pick up hose on a RAM set up with a 4" X 10" vent under the right Headlamp. I know I will get more air, and save about 10 pounds in weight. I hope to test this weekend.

I had problems with the old filter getting wet in heavy rain--not through ther tuba, but from heavy Road splash around the filter box.

I am going to take the MAF out and clean it also, while I am at it. There is a lot of dirt on the front screen and it will be easy to remove and clean the probes while I am at it. I have researched this and it should not be a large task.

M&EM · 06-14-2006, 04:58 PM

Couldn't be any more simple. Thanks for showing the way.

Marty

M&EM · 06-14-2006, 05:06 PM

How does one clean the MAF? Is a solvent required or physically rubbing it?.

skitime · 06-14-2006, 05:24 PM

A light rub of the finger is all I needed to do.

Hamie · 06-14-2006, 06:48 PM

Good job.

..looks great..still have not tried my version 2. Another week then off to a Texas Boomer rally.

abarkl · 06-14-2006, 08:57 PM

I really like your simple redesign for two reasons: I can keep my K&N filter, and have easier access to it!
I have but two questions...Is that the MAF sensor between the filter box and new tube, and can I buy the new tube at most auto stores?

troth · 06-15-2006, 04:35 AM

IMHO, skitime's design is the best yet! I'm also interested in where he purchased the 4" dia. rubber "S" tube...

skitime · 06-15-2006, 05:24 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jestme13:

Nice idea, looks like a nice KISS system. Is the noise that bad that a restrictive baffle needs to be used. I think that sitting directly over the radiator will cause it to swallow more hot air then if it were off to the side, behind a head light. Again, NICE JOB, </div></BLOCKQUOTE>

thanks for the compliment. The noise is not that bad but I just want to develop the concept more. If I can quiet it down without being restrictive that would be a good thing. Engine and radiator heat will be behind the radiator because of air flow.

skitime · 06-15-2006, 05:39 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by abarkl:
I really like your simple redesign for two reasons: I can keep my K&N filter, and have easier access to it!
I have but two questions...Is that the MAF sensor between the filter box and new tube, and can I buy the new tube at most auto stores? </div></BLOCKQUOTE>

Thanks.

1. Yes, the mass air flow sensor is between the filter and new tube.

2. No you will not find this tube at auto parts stores. I had found and used this intake tube for my highly modified 1988 Fiero GT with a 3800 supercharged intercooled Grand Prix GTP engine in it so I knew it was the right shape. I found it at a Volvo truck dealer. It is part number #21907-3210 and costs $54.97 plus tax at my local dealer. The good thing about this tube is it has a steel spring inside to prevent collaspe if the air filter gets wet.

skitime · 06-15-2006, 05:55 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by troth:
IMHO, skitime's design is the best yet! I'm also interested in where he purchased the 4" dia. rubber "S" tube...

</div></BLOCKQUOTE>

Thanks troth and also thanks for helping me to post pictures.

rogueii · 06-15-2006, 06:45 AM

You use Electronic cleaner. You take the MAF apart and spray the two probes (but DO NOT Touch Them) They are very delicate. If you break them you will be spending some $$ to replace it.
Put it back together the way it was.
There are some white papers that suggest cleaning the MAF whenever you clean the air filter.
Do a Google on "How To Clean The MAF"