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Velocity stack

V

voudoux

NAXJA Forum User
Location
Piedmont NC
I have read a lot on throttle body spacers and really don't see how they would help,have never tried one so can't say from experience. But I have not seen any thing on velocity stacks being tried on the Jeep 4.0 or 2.5. They would tend to straighten out the air flow into the throttle body as the stock rubber connector goes from 90 right into the throttle body. You would be limited by hood clearance on the length, have't checked on max length you could use. Has anyone tried this? Thanks
 
I don't think you'll have enough room to run a stack tall enough to make any difference...plus it's a jeep....kinda needs a filter for any normal jeep type uses. For a drag only application maybe you could do it, but why??
 
trippled said:
Not to mention it makes another 90 right after the TB. The spacers work on carbs by allowing the fuel more time to atomize, but are 100℅ worthless with MPI
Click to expand...

I wouldn't say 100% worthless......they make someone rich......:yelclap:

No matter what you try to do before the TB, the TB will mess it up.

Spacers on a MPI system WILL give you more plenum volume, but that only helps in high RPM situations.....
 
Don't let the hood hold you back!
sddefault.jpg
 
TRCM said:
I wouldn't say 100% worthless......they make someone rich......:yelclap:

No matter what you try to do before the TB, the TB will mess it up.

Spacers on a MPI system WILL give you more plenum volume, but that only helps in high RPM situations.....
Click to expand...

Correct, it will give more plenum volume. But you may or may not need it.
 
No one seems to know much about velocity stacks and if they will make any change, I will let you know as I am working on one and yes it will have a filter and fit under the hood unlike 96Sportxj's Chevelle. Thanks for the replys.
 
If it fits under the hood, it won't do much.

Stacks are meant to align airflow to provide more dynamic pressure to 'ram' air into the carb.

Think of it this way...turn on your garden hose, to a mid position....water comes out, but not under a lot of pressure...now block off 1/2 of the opening....now you have plenty of pressure.

A stack simply gets all the air flow going in 1 direction, and without any sharp bends. Without a stack, a carb sucks air from everywhere,.and that doesn't lend well to developing dynamic pressure to give the ram effect
 
I am asking all of these questions because on my 98 2.5 ,4 cyl, 5 sod,xj I changed the rubber conecter from the air cleaner box to the throttle body. I went from a stock 2.5 to a stock 4.0 to get rid of the two large ports on the 90 degree . After doing this I noticed a difference , the engine was not as responsive ,did not pull quite as smooth and strong between 3000 to 5000 as before. After looking at what I had done the only difference other than the two ports that were plugged with plugs that were contoured on the inside ,was the stock 2.5 conecter is a little over 1 inch longer from the elbo or 90 to the throttle body. I think this extra length helps straighten out the air flow a little better than the 4.0 that goes from the 90 directly into the throttle body. This is just something I am working on and was looking for some other views . Thanks got the replys
 
voudoux said:
I am asking all of these questions because on my 98 2.5 ,4 cyl, 5 sod,xj I changed the rubber conecter from the air cleaner box to the throttle body. I went from a stock 2.5 to a stock 4.0 to get rid of the two large ports on the 90 degree . After doing this I noticed a difference , the engine was not as responsive ,did not pull quite as smooth and strong between 3000 to 5000 as before. After looking at what I had done the only difference other than the two ports that were plugged with plugs that were contoured on the inside ,was the stock 2.5 conecter is a little over 1 inch longer from the elbo or 90 to the throttle body. I think this extra length helps straighten out the air flow a little better than the 4.0 that goes from the 90 directly into the throttle body. This is just something I am working on and was looking for some other views . Thanks got the replys
Click to expand...
Do you have the dyno sheets to prove this? Lots of people claim their butt dynos are spot on only to see the dyno proving them wrong.
 
No one has done it

By all means try and report back
 
No,do you have one showing me wrong, I did not claim lots of horse power gains, l admit that running smoother may have felt like stronger or maybe it actually was stronger. I am going to keep working on this with a open mind,as no one has admitted to trying the velocity stack idea.
 
Unless you're making your own manifold and running them sideways, you're wasting your time.

Like building a 4 lane onramp to a 2 lane highway.
 
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