Wackpackxj

Let me start off by saying I'm hoping to keep this discussion technical. Less talk about simple bolt on items such as exhaust, intake, magical computer programming etc.

We've all done enough research to know that most 4.0 owners who crave power through modification believe or preech that the 4.0 just is what it is.

I'm a non believer of this stereotype.

I would like to hear about tried and true, trial and error internal mods such as valve timing, aftermarket cams, lifters, springs, manifold porting and polishing, fuel and spark delivery, higher compression.

I once had an interest in small Honda engines and there was a laundry list of these mods I had done to my own 1.8 liter Acura integra and the results were always good. Even something as simple as removing my power steering and air conditioning with a set of under dive pulleys kicked things up quite a bit.

So with that being said I just wanna see what's possible without a high dollar stroker kit or forced air.

93XJLI

theres a reason theres no replies.

20-30 crank horsepower is all you can get without FI or stroking. and thats being generous. the ECU is barely tuneable and even with an adjustable MAP you wont see any gains unless youre running a stroker/turbo/SC.

a 4.0 isnt a B18. youre wasting youre time to be honest.

BBuchta

Unfortunately its a very old design, basically a tractor engine. The up side to that is cheap parts, low maintenance and great longevity. The bolt ons don't add enough power to be worth the cost, that's why everyone goes stroker, forced induction, or V8 swap, with those you get the gains you pay for.

SeriousOffroad

Noticeable gains when you add the right combination of bolt-on's.

By improving the intake and exhaust you'll get a definite increase in Butt-Dyno HP.

While the intake and exhaust are off the head, port matching can result in a few more ponies too.

Wackpackxj

Bummer.

Swapping my 99 head for a 96 sometime this week.

Naturally I wanted to swing for better performance, heck at least see a spec of improved performance in any aspect. Even throttle response or mileage. Not that I can complain about almost always 300 miles per tank that I've come to expect.

SeriousOffroad

Port and polish the head before the swap.

Wackpackxj

I was dead set on at least the port, polish and gasket match.

But it's not unheard of for this to actually hurt performance.

While resurfacing the head would it hurt to shave a little extra? Increased compression has always been considered a good thing but also I second guess this. Only because I'm inexperienced with tuning anything other than a four banger.

Wackpackxj

I should also add that this makes my 4th Xj in the last ten years. All previous being 96 4.0 HO. Had it not been for this BS 99 cylinder head crack that I now gave the pleasure of experiencing I would otherwise just keep em stock and maintained as I've always done.

Put just under 300k on my first engine without ever replacing anything critical.

Besides removing a motor mount ONLY to replace some O-rings on my oil filter elbow to stop a pretty serious leak.

je4reyk

One place just about everyone overlooks is advancing the crank sensor ,it helps a little.

Jeepzjlover

How does one go about doing that?

Wackpackxj

I've replaced a few crank sensors.....can't recall having to nor do I recall the possibility for adjustment. If advancing the timing is what he's referring to my guess would be an adjustable cam gears? I honestly think maybe you're confused. No pun intended I just call it like it is. And after all we are all here for a number of reasons. Learning or understanding is one of them. So hopefully somebody else wants to correct your questionable suggestion.

CobraMarty

CAI, 62mm TB, '99+ intake, headers, 2.5" cat back will add 15rwhp and 15rwtq.
1.6 Harland roller rockers 3-5hp, 1.7 YellaTerra rockers 5-8hp
hypertech, 'chip', TB spacer Zippo increase.
advanced CPS mod 5hp
'ported' head 5hp
cam 5-10hp and move the power band higher

M62 supercharger +60rwhp and +70-80rwtq Priceless!!

cruiser54

Match port the intake and exhaust ports on the head and intake manifold to the stock gasket. I've done 3 of them. There is no LOSS of power. That's a crock of **** perpetuated by those who have never done it. Obviously Frank from Serious Off Road and I have done it with excellent results.

SeriousOffroad

Yep-a-Doodle!

cruiser54

I'll tell you a story about the port matching some time.

From a factory engineering guy......