Jeep Strokers

Hi there,

Just to bring you all up to speed I currently have a 4.0 98 TJ with a blown transmission and a motor that burns around a quart of oil every hundred miles. Currently in the process of swapping the transmission to an NV3550 which has it's own set of headaches but that's not for here. I have a couple hardcore Jeeping buddies who only wrench their own stuff; we have access to a decently stocked garage. Also the one has rebuilt the 4.0 twice with great success for his other friends but never done a stroker. Instead of doing a simple rebuild they're pushing me to stroke the motor myself as I do not need it as my DD until May, so we have time to work at a resonable pace to figure everything out. If it breaks you may as well get the upgrade right?

We're going to pull the motor out and start tearing it apart to see why its ripping through so much oil (only 69k on the motor, I'm assuming previous owner got mud in the engine I'm really not sure yet). I have a good machine shop not too far away to do any machining I will need. I've been lurking on these forums for a while and I've seen Cheromanic's poor-man 4.6.

4.6L modified "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith Black UEM-IC944-020 pistons
9.25:1 CR
Stock 4.0 HO camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.070" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, Accel 24lb/hr injectors with stock 49psi FPR for '96 and later engines

The only non-stock parts you'll need are the 258 crank, IC944 pistons, and Accel 24lb injectors.

Is this comparibly reliable as the original 4.0? Also what, if any parts would be a good upgrade for reliability if cost isn't too much of a factor. I'm willing to spend money to improve reliability, I'll have enough power I'm sure. I appreciate any help in advance and plan on documenting our build here on the forums.

Reliability differences between the 4.0 and a stroker is a tough comparison to draw a conclusion from. The machine work/assembly that a factory 4.0 receives is top notch in every aspect.. This is why many of them run for so long. The stroker motors tend to see so many more variables ie: aftermarket components, valvetrain geometry, assembly practices, sub par machine work, break in procedure etc... This is why it's hard to compare the two. In a perfect world, if they were both assembled with the same components at the same factory... they would both provide a long service life. Both the 4.0 and the 4.2 have always proved themselves to be strong and very reliable engines. Before building one, do as much research as possible on these motors so you can avoid any potential problems. Attention to the right details is key.

hopup wrote:I've been lurking on these forums for a while and I've seen Cheromanic's poor-man 4.6.

4.6L modified "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.0L 6.125" rods
Keith Black UEM-IC944-020 pistons
9.25:1 CR
Stock 4.0 HO camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.070" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, Accel 24lb/hr injectors with stock 49psi FPR for '96 and later engines

The only non-stock parts you'll need are the 258 crank, IC944 pistons, and Accel 24lb injectors.

Is this comparibly reliable as the original 4.0? Also what, if any parts would be a good upgrade for reliability if cost isn't too much of a factor. I'm willing to spend money to improve reliability, I'll have enough power I'm sure. I appreciate any help in advance and plan on documenting our build here on the forums.

It's like 6TIME said. Accurate machine shop work, clean assembly practices, and a proper break-in procedure will also be important factors that'll determine engine longevity as much as the quality of the parts used.
The modified poor man's stroker is closest to the original 4.0 in terms of the parts used so there are potentially less reliability issues. I'd definitely recommend a set of new ARP 112-6001 rod bolts on any stroker build as these are the most critical parts of the engine and are subjected to the most punishment.