TBS, to add or not too add

[indianaXJ]

hello;

I finally installed my Y2K intake, and kolak exaust system, sweet.

Given the Y2K's increased intake volume do you think adding a TBS would be pointless or counterproductive?

 

[tealcherokee]

hello;

I finally installed my Y2K intake, and kolak exaust system, sweet.

Given the Y2K's increased intake volume do you think adding a TBS would be pointless or counterproductive?

its pointless on a regular intake

 

[j99xj]

Throttle body spacers gain some low end torque (5 lb-ft) and add some fuel economy (0.8 mpg).

I thought it might not be effective on my 99 intake manifold with the larger volume but the spacer just adds that much more performance. It was definitely worth it for me.

Here is some advice on buying a throttle body spacer:

DON'T buy a tbs with a colorful or shiny box with any kind of brand name on it, they are far too expensive and the "swirls" and "helixes'' do nothing but restrict flow.

DO save yourself some money and buy one off ebay. I bought my 62mm SMOOTH BORE tbs for about 27 bucks shipped, it was a steal. I found it under one of those "buy it now " things so it was very easy to get.

 

[5-90]

Throttle body spacers gain some low end torque (5 lb-ft) and add some fuel economy (0.8 mpg).

I thought it might not be effective on my 99 intake manifold with the larger volume but the spacer just adds that much more performance. It was definitely worth it for me.

Here is some advice on buying a throttle body spacer:

DON'T buy a tbs with a colorful or shiny box with any kind of brand name on it, they are far too expensive and the "swirls" and "helixes'' do nothing but restrict flow.

DO save yourself some money and buy one off ebay. I bought my 62mm SMOOTH BORE tbs for about 27 bucks shipped, it was a steal. I found it under one of those "buy it now " things so it was very easy to get.

Do you have any quantitative analyses of this (e.g. dyno sheets or G-Tech meter readings,) or is this done via "butt dyno?"

I'm honestly curious - most of what I've read on throttle body spacers is either rubbish or gibberish (or both!) and I've yet to see any reports that WEREN'T done by the manufacturere as marketing fluff...

5-90

 

[j99xj]

Do you have any quantitative analyses of this (e.g. dyno sheets or G-Tech meter readings,) or is this done via "butt dyno?"

I'm honestly curious - most of what I've read on throttle body spacers is either rubbish or gibberish (or both!) and I've yet to see any reports that WEREN'T done by the manufacturere as marketing fluff...

5-90

I got the 5 lb-ft and 0.8 mpg figures from Dr. Dyno. The throttle body spacer makes the most different at moderate throttle openings from about 1500-2500 rpms. It makes about 3 lb-ft difference at the torque peak and maybe 1 or 2 hp at 5000 rpm. And yes, it is detectable. I could break the back end of my Jeep loose much easier making right hand turns from stop signs.

The best spacers are the smooth ones. The shiny box ones with the "swirls" are the crappy ones.

 

[5-90]

The best spacers are the smooth ones. The shiny box ones with the "swirls" are the crappy ones.

I'd figured that bit - that's a holdover from "wet" manifolds (TBI and Carburettors) where a certain amount of intake turbulence was desirable in order to maintain fuel suspension and reduce puddling. The "dry" TPI/MPFI manifold eliminates this.

I'll have to sandbag Dino and see where he got his numbers, then. He's usually quite good about sources anyhow - probably comes from being an M.D.

5-90

 

[j99xj]

I'll have to sandbag Dino and see where he got his numbers, then. He's usually quite good about sources anyhow - probably comes from being an M.D.

5-90

He's the most credible person on this forum, in my opinion. He has the best website for the Jeep 4.0 on the entire internet, again in my opinion.

 

[5-90]

No argument at all - his numbers are usually quite good! His raw data is very good as well, and I took it as high praise when he complimented my book (I sent him a copy, since I bounced ideas off of him...)

It's just a basic rule of mine - "If you can't describe it mathematically, it don't matter. If you can't verify sources, it ain't data."

5-90

 

[tealcherokee]

i TBS might give you half a nut hair more low end torque, but its going to take the same amount away from the top. a longer intake manifold will move the torque curve, thats it

 

[j99xj]

i TBS might give you half a nut hair more low end torque

Thats what we want.(at least what I want) I'm almost never above 3500 rpm unless passing. My engine loafs along around 2000 rpms most of the time. The spacer works quite well around 2000 rpms.

 

[MaXJohnson]

i TBS might give you half a nut hair more low end torque, but its going to take the same amount away from the top. a longer intake manifold will move the torque curve, thats it

The effect of a throttle body spacer is to increase plenum volume, not increase intake runner length. This changes the intake reversion wave timing and is the reason why power can be enhanced at a particular point in the torque curve (and reduced in other areas). Increasing the amount of air packed into the cylinder also increases the demand for fuel, so an increase in fuel economy is not likely.

 

[tealcherokee]

The effect of a throttle body spacer is to increase plenum volume, not increase intake runner length. This changes the intake reversion wave timing and is the reason why power can be enhanced at a particular point in the torque curve (and reduced in other areas). Increasing the amount of air packed into the cylinder also increases the demand for fuel, so an increase in fuel economy is not likely.

yes. plenum volume and runner length are the same in this situation. a spacer between the head and the intake would do the same thing

 

[MaXJohnson]

yes. plenum volume and runner length are the same in this situation. a spacer between the head and the intake would do the same thing

not really

if you think they are the same, you're not thinking about it right.

think about how an intake runner and plenum work together, together, they form a spring/mass system with the reversion wave acting as the mass and the plenum as the spring.

 

[tealcherokee]

not really

if you think they are the same, you're not thinking about it right.

think about how an intake runner and plenum work together, together, they form a spring/mass system with the reversion wave acting as the mass and the plenum as the spring.

yes i understand how they are different, in the real world, where it matters.

but here in throttle body spacer land, the minimal effect that it will produce, theorectically, its doing the same thing.

if we were comparing a 4 foot runner to a 1" spacer, obviously the results are going to be very different.

 

[indianaXJ]

Thanks for the input j99,max.

A low/mid gain is what I am looking for also. The new intake and exaust( 5lbs of carbon removed from the head ) made quite a difference accross the board, but mostly on the high end. I'll try one after I have the TB opened up.

Has anyone ported their head, and what difference did you notice?
Can someone recomend a place to have the TB bored?