Throttle body flow testing [Archive]

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Rover

11-03-2007, 10:43 PM

It has been said that a cheep way to make more power with your 2.5L is to swap a 4.0L throttle body onto your engine. The 4.0L "should" provide the engine with more air, which = more power. In addition to the throttle body, you can also add a throttle body spacer. A throttle body spacer is supposed to straighten out the air and reduce turbalance in the air stream and alow the air/fuel mixture to atomize better.It will also provide a cooler more dense charde. Many of the people who have swaped the throttle bodys claim to feel a difference by the "seat of your pants" dyno. After some discussion among TWH, I decided to compare the two throttle bodys and some different spacers. My goal is to provide definitive evidence on which tb flows better and to also complete a project for my air flow class.

I first want to thank Sam (Sglide) for the 4.0L throttle body and Ben (Bigben) for letting me use some wood and some tools to make my adapter.

My plan is to first flow the 4.0L throttle body in stock form to get the CFM, velocity and swirl. Next, I plan to flow a 2.5L throttle body so get the same measurements. After flowing the throttle bodys I will make some homemade spacers to test out different designs. The throttle bodys will then be tested with the spacers. In the end, we will be able to see which combination flows the best.

Day 1:
I started out with a used stock 4.0L throttle body off an Xj

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0471.jpg

It was in need of a good cleaning

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0473.jpg
http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0475.jpg

Next, i did a rubbing of the bottom of the throttle body. This would allow me to make the spacers and adapters the exact size of the throttle body.

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0472.jpg

To flow the throttle body on the flow bench, I needed to make an adapter. The adapter is made out of particle board, but I may make a new one out of MDF

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0478.jpg

To make sure I have a complete seal on the adapter, I made a gasket out of cork gasket material.

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0477.jpg

Next everything was test fit

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0483.jpg
http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0479.jpg
http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0480.jpg

Then secured together

http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0484.jpg
http://i117.photobucket.com/albums/o74/landrollover/air%20flow%20project/IMGA0485.jpg

On monday the 4.0L throttle body will be tested. Im still looking for a 2.5L throttle body to test. I should have all the data ready to post up monday alnog with pictures from the first test.

BIGBEN

11-03-2007, 10:46 PM

that is a sexy particle board adapter.

can you make me one? :sheep:

Rover

11-03-2007, 10:48 PM

:hehe:, that was a pretty good adapter considering our working conditions and tools

sglide

11-03-2007, 11:08 PM

thats really cool nick
i wish i had your template i would make you an adapter out of steel

MuddyPaws 3.0

11-04-2007, 02:07 PM

thats really cool nick
i wish i had your template i would make you an adapter out of steel

x2

Isn't that adapter going to mess up the results?

Rover

11-04-2007, 02:20 PM

the wood adapter should be fine for now, as long as the hole in the adapter is bigger that the tb bore it will be alright. the picture makes it look pretty bad.i radiused the hole with a dremil tool afterwards

MuddyPaws 3.0

11-04-2007, 06:25 PM

dremil .....you are so high tech.

:hehe:

Flow benching and you can't find a router. :rofl:

BIGBEN

11-04-2007, 06:44 PM

dremil .....you are so high tech.

:hehe:

Flow benching and you can't find a router. :rofl:

we had limited tools at the workshop. you should have seen us cutting it out with the sawzall.

Rover

11-04-2007, 06:56 PM

dremil .....you are so high tech.

:hehe:

Flow benching and you can't find a router. :rofl:

Im working with what I got, all my tools are 600 miles away

Grandman

11-04-2007, 07:14 PM

Id like to suggest putting a piece of shim stock around the hole in your adapter . That will create a smooth surface and is easy to work with . Any decent auto parts will have it . You can bend it with your hands easily and smooth the bore in the wood up and prevent any notcible turblance from the wood .

sglide

11-04-2007, 08:10 PM

you will have a steel adaptor very soon

Rover

11-04-2007, 09:33 PM

sweet, the hole looks pretty bad in the pics, i havent loaded up the pics after i smoothed it out

Mongo

11-05-2007, 01:13 AM

Do you want a router on December 1st?

Rover

11-06-2007, 06:22 PM

Do you want a router on December 1st?

thanks for the offer mongo. Sam and I discussed a steel adaptor after his first reply. I flow tested the setup monday with great results. But i forgott to take my camera to lab. :banghead: The adaptor worked very well. Only 2.9 Cfm leakage (which is comparable to all the heads weve flown on the bench)The throttle body flowed 394 cfm with no swirl. Velocity was about equal through out the tb even below the wood adaptor . The one spot were velocity dropped was under the void in the entrance. Velocity was 20% lower at this point (1/8" from tb wall)

Tonka

11-08-2007, 09:39 PM

Just a FYI in case it is not already known. The 4.0L throttlebody pictured above is from a non-H.O. 4.0L with the RENIX fuel injection system, and is not a direct bolt on for the 2.5L.

You need one that looks like this:
http://www.4x4wire.com/jeep/tech/engine/throttlebody01/body2.jpg

http://www.alljeep.com/images/alljeep/throttle_body_before.jpg

http://www.alljeep.com/oscommerce/images/throttle_body_after.jpg

The 4.0L throttle body can be bored to from 54mm at it's lowest dia to a straight through bore of 62mm, and then matched to the intake (2.5L and 4.0L)

I have done this on my TJ and my old YJ, and have run a matched 1" throttle body spacer on both.

sglide

11-10-2007, 09:32 PM

Tonka

11-11-2007, 07:09 PM

It smoothed out mid range acceleration on both vehicles.
The tj needs an exhaust to see full benefit, as it is still stock, with a disintegrating cat.

The yj had a slight seat of the pants improvement in the 2500 to 3500 range, but it had a dynomax cat back and random technologies cat.

I bored mine with a dremmel and used various polishing compounds to smooth it out.

A porting kit (carbide bits and a drill) works too.

I would not go spend $400+ on throttle body crap, unless you have a stroker, and cannot machine the parts yourself.

Rover

11-12-2007, 01:03 PM

Thanks for the info tonka, i dident know some xj's used a different tb :banghead: Im just going to test different spacers on this tb then.

sglide

11-12-2007, 02:37 PM

Thanks for the info tonka, i dident know some xj's used a different tb :banghead: Im just going to test different spacers on this tb then.tonka knows his shit, no doubt!

Tonka

11-12-2007, 08:27 PM

Any 4.0L before 1991 used the renix setup. There were wiring / tuning revisions to the mopar MPFI and the heads, blocks, cams, intake , ignition system and exhaust had changes throughout the years. (1991- 2006)

squeak003

11-21-2007, 03:15 AM

that would be sweet if someone can get him the right tb for this.....im thinking about doing this and have been looking for info on it but all i can find is how to info..