Different types of throttle bodies

[MeanLemons]

I had my hands on so many throttle bodies over the years. Probably over 200 of them. AND I just recently actually noticed this....

 

for 91-95 HO engines. There’s two types of throttle bodies and I can’t figure out why there is a difference. 

 

Theres the smooth and the ribbed.  (No I'm not talking about condoms lol.

 

I’m wondering why there’s a difference? Perhaps it’s early HO such as 91-92 then there’s 93-95? (I just came up with the numbers). Or is it a vehicle specific? Such as XJ/MJ? 

[HOrnbrod]

One difference is the throttle body mounting for the MAP sensors on the newer ones.

[MeanLemons]

1 minute ago, HOrnbrod said:

One difference is the throttle body mounting for the MAP sensors on the newer ones.

That’s right   I mean I knew that 96-04 had same TBs with MAP mount on the side.

 

its the two different 91-95 TBs that had me wondering why one is smooth and another is ribbed. 

[AeroNautical]

It almost looks like a heat sync, to cool the air as it's venturied into the intake manifold. Thats ridiculous though, it probably has something to do with strength. 

[MeanLemons]

5 minutes ago, PFCLeist said:

It almost looks like a heat sync, to cool the air as it's venturied into the intake manifold. Thats ridiculous though, it probably has something to do with strength. 

Right. I wanted to know why it changed and when was the change taken effect. On what years and what jeep model. 

[HOrnbrod]

That is strange. Just for grins I looked in the parts manual, and the XJ/MJ 91-95 4.0 engine throttle bodies all carry the same p/n, 53030844. It changed in 96 due to the MAP mount. 

[Jeep Driver]

Chrysler probably changed vendors

Two different vendors two different designs

[MeanLemons]

Out of 4 throttle bodies I had. (One ribbed 91-95, two smooth 91-95, and one 96+) they all had different numbers stamped on the bottom

 

even between two identical smooth 91-95 TBs. 

 

 

[HOrnbrod]

They look like casting numbers...

[Pete M]

the ribbing could be for strength.  seems unlikely they would be for cooling since the ambient air in the engine bay is wicked hot.  

[MeanLemons]

9 minutes ago, HOrnbrod said:

They look like casting numbers...

Indeed   I also noticed that those smooth TBs doesn’t have mopar part numbers on the IAC housings. Makes me wonder if they were aftermarket replacements?