Throttle body spacer?

Spacers will improve performance but most all the gains your going to see are at higher rpm's. If your after low end torque for the trails I don't think you'd see much improvement. Same with aftermarket exhaust. Larger pipe diameters work great for higher rpm's but can hurt the bottom end. Not enough backpressure at low speeds ruins the scavanging effect that helps pull exhaust gases out of the motor. I would check with the manufactuers of these products and explain the intended use of you vehicle.(ie. how tall of a spacer, how big of a pipe should I run, what other mods are on the vehicle). Most of these companys have done alot of testing and probably no exactly what will work for you. hope this helps!!
 
I couldn't see you getting anything over 2-3hp, if that. Its not worth the money unless you make it yourself or you can get it for very cheap. What year and engine does your jeep have?
 
I bought one because I had a $50 credit from Summit racing that was going to expire. I didn't really notice much of a difference.

Take the money and get some champion truck plugs, Beldin wires, cap and rotor and an air filter. That will probably be more of a benefit then the spacer.
 
bfred said:
Same with aftermarket exhaust. Larger pipe diameters work great for higher rpm's but can hurt the bottom end. Not enough backpressure at low speeds ruins the scavanging effect that helps pull exhaust gases out of the motor.
Click to expand...

The loss of bottom end torque from an open exhaust is almost always caused by the air/fuel mixture and ignition timing not being "tuned" to the less backpressure. This was more an issue back in the days of carburettors and contact points.

But now, the computer will know if the exhaust is flowing more cfs (oxygen sensor) and should adjust the fuel mixture/timing accordingly to minimize emissions and maximize economy.
 
I put a poweraid spacer on mine and noticed it immediately. Throttle response is better, among all the mods i've done (catback, k&n, livewires ign. kit) it was the only thing that I actually noticed a difference.
 
TRSCobra said:
I put a poweraid spacer on mine and noticed it immediately. Throttle response is better, among all the mods i've done (catback, k&n, livewires ign. kit) it was the only thing that I actually noticed a difference.
Click to expand...
The fact that you have noticed anything is a miracle in itself.:D

Sean
 
TRSCobra said:
I put a poweraid spacer on mine and noticed it immediately. Throttle response is better
Click to expand...
I agree with Cobra. TBS, by itself, u probably wouldn't notice jack. But with a catback, CAI, chip, etc..... it definitely helps. Not so much in raw power, but I noticed a huge difference in throttle response as well.
 
I got me a cheapo one from ebay for $25, I noticed a pretty nice bump in power, however I also installed a 62mm TB also.
 
DIABLOBLANCO8658 said:
:scottm: Has anyone tried a throttle body spacer? Does it make any difference in
performance?
thanks.
Click to expand...

I first installed mine seven years ago when I still had my old 4.0 engine (my '92 XJ has had a 4.6 stroker since July 2004) and I did some before and after timed acceleration runs to see if it made any difference. It did. I calculated that the spacer produced a 3-5lbft gain at lower rpm and 2-3hp at higher rpm. That's not enough to feel it through the SOTP but considering you can buy a spacer for not more than $50, it's worth it.
If you also want to buy and install a K&N FIPK, then you have a problem because you can't fit both under the hood so you'd have to choose between one or the other. The best choice here would be the FIPK (but make your own homebrew version 'cause it's a lot cheaper than K&N's).
 
I have one. The PowerAid one. It sounds kind of cool, it whistles at mid throttle between 2-3k rpms, but I'm not sure it does much else. Maybe if the guy above did a before and after test and saw a difference it does, but it's not a very noticeable one.
 
You can get rid of the whistling by feathering the lower edge of the upper IAC bypass opening in the throttle body. You can also have the TB spacer bored out to 62mm. This gets rid of that useless helix.
 
jbmoose said:
I agree with Cobra. TBS, by itself, u probably wouldn't notice jack. But with a catback, CAI, chip, etc..... it definitely helps. Not so much in raw power, but I noticed a huge difference in throttle response as well.
Click to expand...
the best way to NOT know if a particular modification helped is to make several changes at once. Who's to say which ones helped and which didn't?
 
j99xj said:
... the computer will know if the exhaust is flowing more cfs (oxygen sensor) ...
Click to expand...
none of my oxygen sensors know how many cfs's (or cfm's) the exhaust is flowing.
 
You can fit a TB spacer and K&N FIPK under your hood. You just have to make (or buy) some 1/2 or 3/4 inch hood spacers for your hinges. Also helps with heat dissipation....
 
MaXJohnson said:
none of my oxygen sensors know how many cfs's (or cfm's) the exhaust is flowing.
Click to expand...
Yes, of course the oxygen sensor by itself won't know the mass flow rate, but that's not what I meant. I meant the computer would use the signal from the o2 sensor to help it guess what the flow rate is.

If an exhaust system is flowing more, that would mean more air is flowing into the engine, by the continuity equation Q=AV.

More air flowing into the engine will lean the fuel mixture and the signals from the o2 sensor (along with the map sensor), would know this and tell the computer to add more fuel.

More fuel burned means more power produced as long as there is enough air to help it burn. Also there are lower head losses with bigger pipes which allows more power to reach the wheels rather than forcing more exhaust through a smaller pipe.

That's why fuel injected engines are more adaptable to exhaust and intake changes.

If you had a perfectly tuned carburetted engine, and changed to a free flowing exhaust, you would have a power loss. But that power loss is not from "loss of backpressure" or any other nonsense like that, its because its running lean and can't adjust the air/fuel mixture without new adjustments and/or jets.

You will probably come back and say to me "If bigger pipes are better, why didn't they come that way from the factory?" That is easy. Bigger pipes are more expensive and that would do nothing for Jeep besides reduce their bottom line profit. Car companies are in the business to make profit, and they will do everything they can to maximize it. (I have no problem with this, it is just the way it is, a captialist system, which I am in full support of.) But that just opens up many opportunities for small businesses to make aftermarket parts, which I am in full support of also.
 
Last edited:
j99xj said:
Yes, of course the oxygen sensor by itself won't know the mass flow rate, but that's not what I meant. I meant the computer would use the signal from the o2 sensor to help it guess what the flow rate is.
Click to expand...
The computer doesn't use the signal to determine flow rate in any way, shape or form. The computer does care about air/fuel ratio. It doesn't know or care about flow rates(air or exhaust).

j99xj said:
You will probably come back and say to me "If bigger pipes are better, why didn't they come that way from the factory?" That is easy. Bigger pipes are more expensive and that would do nothing for Jeep besides reduce their bottom line profit. Car companies are in the business to make profit, and they will do everything they can to maximize it. (I have no problem with this, it is just the way it is, a captialist system, which I am in full support of.) But that just opens up many opportunities for small businesses to make aftermarket parts, which I am in full support of also.
Click to expand...
I probably wouldn't come back and say to you "If bigger pipes are better, why didn't they come that way from the factory?", but you did. By your logic, smaller pipes are less expensive, so why didn't the factory put on smaller pipes? In reality, engineers specify the exhaust based on compromises of power, economy, cost, noise reduction, ease of manufacturing, material availability, etc. Depending on the target market, they may lean towards less expensive or more expensive in a gamble to sell more units.
 
MaXJohnson said:
By your logic, smaller pipes are less expensive, so why didn't the factory put on smaller pipes? In reality, engineers specify the exhaust based on compromises of power, economy, cost, noise reduction, ease of manufacturing, material availability, etc. Depending on the target market, they may lean towards less expensive or more expensive in a gamble to sell more units.
Click to expand...

Yes, good point. And you answered that quite well. The engineers at Jeep wanted at least 190 hp out of the 4.0 and put on an exhaust that would allow that for the least amount of money along with other acceptable qualities like you mentioned. But I and many others know that a 4.0 is capable of much more than 190 hp. But as always there is no free lunch as horsepower costs money.

I know a little bit about multi criterion decision analysis. I'm in civil engineering so I have experience with project management with big stuff like dams and such. I could write an Excel program (with custom VBA code and what not) all about it if I wanted to, but that would cut deeply into my leisure time which is already very limited as an engineering student.

I really shouldn't be on this forum as much as I am to be quite honest. But I like to talk Jeep.
 
You must log in or register to reply here.

Similar threads

F
Larger Throttle Body - Effect on Throttle
Replies
9
Views
459
Tim_MN
Tim_MN
G
1997 XJ won’t rev high and loss of power
Replies
8
Views
312
Tim_MN
Tim_MN
J
Xj wont start
Replies
3
Views
327
lawsoncl
L
B
1996 4.0 4wd Jeep xj p1391 code.
Replies
5
Views
234
clean96XJ
C
K
1994 xj wont start unless wot
Replies
16
Views
493
kjcain
K
Back
Top