[jojopi3]

hi my friend, last year I tryed to build an offroad-only jeep's...staying with the stock 4.0l engine but with a turbocharger. At my first try, (1999 4.0l with 180 miles) I just put a checkvalve before the map sensor and running at 8psi aaannnd 2 hour later a connecting rod was threw outside the engine block lol. after that I've swapped it for a 4.0l (2000 distributorless with 108 miles on it) with a new turbo setup at 8psi again (36lbs injector, liquid to air intercooler, split second ftc1-201 fuel/timming controller running on 8psi 34 lbs injector base map) after 1 week its worked fine, good compression (135- 145psi on each cyl.) but after 2 months a grey smoke started to comming out and alot of blow-by.... the compression was +/- 50-80 psi on all 6cyl.

What can cause that? till something I miss when I build it? i'm new to that but I knew even if I running 36lbs injector with a 34lbs injector map its better to run rich than lean... the engine did'nt really run hot untill 2-3 time at 240f for a few minutes in a mud hole. Now i'm not sure if I go with a fully forged internal or a ls swap...

waiting for reply

 

[Old Dogger]

Welcome to the Forum, from Cave Creek AZ.

 

[Luckymac]

We often call the straight 6 a tractor motor. With two failed motors, I'd think the next step would be LS.
I read recently where some guy got 395HP from a conventionally aspirated stroked 4.0 block. IIRC, he was running forged rods and a whole lot of other specialty race motor goodies.
The 4.2-4.0 motors have 7 main bearings that should make the bottom end bullet proof. Next to fail would be the rods (which you found out on the first motor). If you plan on using another 4.0, you might contact a specialty piston manufacturer.

Good Luck, L.M.

 

[jojopi3]

I check to swap a 4/6bt or a ls... what ls engine would you recommend and of what car/year?

 

[Muffin Top]

Do a long-stroke conversion of the 4.0 engine, so you won't have to re-engineer any sensors/ electronics. Replace your crankshaft with a 4.2L crank, and 4.2L short-rods. This will increase your displacement to 4.5L, and the extra low-end torque will feel good.

The last time I checked a few years ago there was a company selling new crankshafts, new rotating assemblies, so you won't have to find it in a junkyard.