Internal Engine Mods - Bore, Stroke, Port, Polish

[B94Sport]

I am considering having internal engine work done on my Explorer to give it some more power. Can anyone who has done this kind of stuff (or knows about) tell me about changing the bore or stroke, or getting different heads and porting and polishing? What kind of gains could you expect from this? Also, a cost estimate if you know that sort of thing. I know nothing about internal engine mods and haven't been able to find much about it in the forums. Thanks

 

[DOGMAN]

I think one of the reasons you have not found much on this topic is that not many people have seriously hopped up a 4.0 OHV motor. There are a couple companies that deal in performance 4.0, they are Vanir Technoligies and 4.0 Litre Performance, a division of Central Coast Mustang. Do a search on both of those and see what you find.

As far as I know, there are no stroker kits out for the 4.0. That is a fairly involved process on any motor, I think your money would be better spent elsewhere.

As far as increasing the bore, sure, you could go 0.030" over, but you're really not going to gain much there.

Getting different heads? I could be wrong, but I don't believe there are any aftermarket performance heads for the 4.0 OHV. The stock heads arn't the best in the world either, they're rather weak in design in certain areas, and that lead to cracks in high mileage motors.

Porting and polishing? Sure, you can do it, but for the money, I don't believe you're going to see a significant horsepower gain to justify it.

There are a few performance camshafts out there, you could go that route. You can also go with roller rockers. But these mods will still not net you the HP I believe you're looking for.

That leads us to supercharging. If you want to substantially increase your available HP and torque, you might want to look into a blower. There is a ongoing thread from Alec about his blower install. He would be a good person to talk to.

Of course you could also swap in a V8, but that is very involved and expensive.

My advice to you would be to start learning more about this subject. Research as much as you can. You admittingly have much to learn about this, and with greater knowledge you can better make an educated decision that will benefit YOU the most. Whichever way you go, significant HP increases cost a good chunk of money. Do your homework.

 

[mdrut]

The easiest way to increase h.p. is the cam..Because you are not changing the induction system, the head work is pointless..I have never heard of anybody stroking a 4.0..Bore, not sure if aftermarket pistons are available..No matter what you do, you are still going to have a small displacement v..Alot of the time it is easier to drop wieght than increase horsepower..You may want to consider a V8 conversion.There are endless combinations for the 302-289 block..

 

[SteveVB]

Well,

Stroking is cost prohibitive, requires a lot of custom parts. The blocks oil pan rails are very close- remember this is already basically a bored and stroked 2.9

Boring you can go to .040 over which wont make a lot of HP maybe add a % or 2.


Heads you can install the later model heads with the smaller chambers to increase the compression ratio, but unless you install a camshaft that needs the increased ratios then Im not sure the cost is worth the 5 hp you could pick up.

ANYTHING YOU CAN DO TO THE HEADS SHOPULD INCREASE POWER IN THIS ENGINE THEY ARE INADEQUATE IMO
Porting the heads should add some power, maybe 10%. It would probably cost north of $500 to have someone do it. A home job with some polishing and port matching is IMO worth the time expended on any engine.

Larger valves would be a great idea. These heads seem to have small valves for the size of the cylinder displacement. The cylinders displace more than a 5.0's, but the valves and heads are much smaller. So there is much room for improvement in that area. The problem is that the heads because of their design wont accept the larger valves without waterjacket problerms and durability. It would be nice to see some 5.0 valves in the heads but the biggest that Ive heard will fit are 1.80/1.40s. That would be a few hundred extra over the cost of a stock rebuild.
World Products was supposed to be working on some heads a while back but I havent seen any info on them lately.


Those are some things off the top of my head.

Cost is up to you. I did a stock bottom end, new cam and valve train job, and I think it cost close to 2000 doing most of it myself( I didnt keep very good track of the costs). Add larger valves, porting and such and you would be past 4000 fast.

Hope that gets you started

 

[SteveVB]

One more thing,

A good source of info is Sven Pruitts 60 V-6 book. You can get it on his site or through Amazon etc.

Its a bit dated and deals with all of the 2.6,2.8.2.9, and 4.0. Not much on the Fuel injection we run but it does have good bottom end info, and some head work info. I would recommend i9t for a read even if your doing a stock rebuild.

 

[B94Sport]

SteveVB,

With the stock bottom end, cam, and valve train job you did, what kind of gains did you notice? I realize you probably didn't go out and dyno it, but what would you estimate?

 

[SteveVB]

estimate?

I have no data to back it up, but I was shooting for 200-210 when I was done. This is from a 4.0 with a .030 over bore, the 410-8 comp cam, port matched intake, borla headers, cat back, 63mm TB, 70mm MAS, open air filter.( I havent installed the MAS yet-it should be here soon)

Someday I will put it on the dyno. It feels stronger, but its hooked to a 160k mile tranny which is scheduled to be rebuilt so it may not mean much, plus Im running 3.55s and 31's so the engine needs some gear. The cam probably raised the power band 3-400 rpm, and the other mods may have pushed that even further dont know. The engine pulls much stronger from 2500-3500rpm it seems. But like I said this is all "feelings" and guesses so it doesnt really mean much.

If I were to do it again I would probably do the same combo, but I would do more work to the heads- that is THE area to get some power. I left the possibility open to run the BBK blower if I get the cash and the itch, but I was going to run the late model heads, and will at somepoint if the blower idea looses my interest. Maybe World will put out some heads, that would be nice, but until then I am going to get an extra set to play with.

If your just going to spend the money to upgrade and not because you need to rebuild- then I would spend the money on the BBK.

 

[B94Sport]

SteveVB,

Thanks for all the info. Right now my engine has 98K miles on it, mostly highway, and it doesn't look like a rebuild is is looming in the near future. It's still running really well. The tranny's a whole different story though... If I do decide to do any internal work, I will definitely wait until I have to do a rebuild. Which brings up the question of a supercharger... But a lot of the people seem to think you shouldn't supercharge an engine with so many miles on it unless it's recently rebuilt (and possibly has better pistons and heads than stock added). Kind of goes in a big circle then. Maybe I'll just go out and buy a chip

 

[tac0meat]

cant stroke a 4.0, ive already looked into it but according to vanir tech there is just not physically enough room for it. would have been cool to have a 5.0 v6 though