4.0 L throttle body in a 2.5L engine

[mrbeggins]

Can anyone tell me what the benefits are of installing a 4.0L throttle body and/or spacer on a 2.5L engine. does it offer more airflow which is sensed by the ECU which then adjusts fuel ratio accordingly giving you more power or am I way off track. any help would be great. thanks you guys.

[BlackYJ]

The spacers do NOTHING at all; reasoning being because most Jeep engines are MPI.

The 4.0L TB does add a little power to the 4 banger because of a larger bore.  However to get more benefit you would port the intake manifold to match.  Now I run mine with 4.0L sensors and it run fine, and my did switched back to the 2.5L sensors and ran fine.

[mrbeggins]

thanks for the reply black yj. what does mpi stand for? also, does a guy have to put 4.0L sensors in with the 4.0L throttle body and if so, which ones ? off topic now, you now have a ford 8.8 installed! we just bought one and are planning to install this fall/winter. did you buy a kit for the bracketry (shock mounts, etc.) or did you use the ones off your D35? how did the install go. did it yourself? ya i know, - lots of questions? any info would be appreciated. thanks byj.

[BlackYJ]

thanks for the reply black yj. what does mpi stand for? also, does a guy have to put 4.0L sensors in with the 4.0L throttle body and if so, which ones ? off topic now, you now have a ford 8.8 installed! we just bought one and are planning to install this fall/winter. did you buy a kit for the bracketry (shock mounts, etc.) or did you use the ones off your D35? how did the install go. did it yourself? ya i know, - lots of questions? any info would be appreciated. thanks byj.

Okay, here are the answers

MPI - Multi Port Injection, ie the fuel is injected at the cylinder.  Spacers work best on carbs because they do more efficiently blend the fuel and air

The sensors switch between the 2.5L and 4.0L, if you switch one you shoudl switch them all.  On the new 4.0L TB there is one sensor now used.  There is the IAC, TB sensor, and MAP I believe.  Just keep them all either 2.5 or 4.0, it really does not matter which ones

As for the 8.8, National did the install and they supplied the bracketry kit as well as the brake and e-brake kit for the swap.  The 8.8 tubes are 3.25" in diameter compared to the D35 at 2.5", so they would have to be modified to fit.  Also they installed the axle about 1" offset to the drivers side to help compensate for the extra 1.5" of pinion offset compared to the D35.

Any other questions shoot me a PM and we can talk

[hps4evr]

mountain off road enterprises(m.o.r.e.) sells an entire kit to put a ford 8.8 into a YJ.

http://www.mountainoffroad.com/more.htm