I want to keep my 98 montero and want more power. What is the best way to achieve this?? I would rather drop a few thousand into this then put it into something else i think.
Right now i need to to a timing belt (6-8K miles) and have an oil leak i want to take care of.
1. Rebuilt and bore engine.
2. engine swap and which one to drop in?
3. Any other ideas you guys have would be great.

Has anyone rebuilt a 3.5, how much more hp would i get, and how much do you think it would cost?
thanks again all.
jason

How many miles are on your engine? Generally speaking, a rebuilt engine is only going to get you back to the original power level that the vehicle came from the factory with, so unless you have very high miles or a lot of engine wear a rebuild won't get you much in terms of additional power. Making sure that your maintenance is up to date (quality Iridium spark plugs, quality plug wires, filters, etc,) and using a synthetic engine oil is more likely to get your engine making all the power it's capable of.

I don't know that anyone has found any simple ways to extract more power from the 3.5 SOHC. The engine is designed pretty well from the factory and they didn't leave much on the table as far as easy performance improvements. Some small gains could be had by going with the maximum overbore pistons on a rebuild, a slight increase in compression from milling the heads, and possibly some airflow gains through match porting the manifolds to the heads, smoothing any imperfections in the ports, and a quality valve job, but you would really need to do your homework beforehand so you don't create any additional issues.

Engine swaps are only limited by how much time or money you want to spend on it. If you have the tools and know-how to do it yourself then the sky's the limit, but more often than not an engine swap is never completed properly and ends up being sold for parts.

In my mind your best option would be to change your axle gears to 4.9's from the 4.2's that your Montero was originally equipped with. The gears can be sourced new or you can hunt the wrecking yards for them - they will restore more acceleration than what you lost with the larger tires that you have.

Wasn't Charlie working on a twin turbo 3.5?

i have 160k on it. I know i haven't read or seen anywhere online anyone who has gotten much more out of the engine. Oh well. I'll just have to suck it up. these newer engines have so much more power than mine. arrhhh. But man, i sure would have to have over 250hp under the hood. I will just have to do the regular stuff once i get a chance.

Since you have a 1998 I would recommend rebuilding the engine and re-gearing the axles 4.63 or 4.89 gears. This is the best solution in my opinion.

Yes and I looked at it when I stole the hood to fix the SR I am driving. I have not gotten back to the project yet.

I swapped a 3.8 Galant engine that I converted to DOHC into my SR. I expect I get the generous side of 250Hp but most of the power is up high. Over 3500 this thing pulls hard to 6500 where it shifts, but down below 3k it lacks power. I just towed a trailer to Conn and back and I find my aging Mighty Max pulls much better. The big problem I have is the wide gear spacing in the automatic in the SR. That transmission just does not let the engine work where the much less powerful engine in the lighter Max can be used efficiently..

If I were to suggest a change for you, get a used 3.8 engine rather that rebulding yours, change to 4.63 gears to reduce the big step to overdrive or keep the 4.22 and swap to a manual transmission so you car use the power the engine makes.
I have a 6 speed manual waiting to go in my SR, maybe in June when I bring an employee on I can get the swap done. This is not a simple swap but the 5 speed from an earlier Montero or from a Sport will go in easily.