New To Strokers With Questions

[qualm]

So I have been lurking here because my new 1999 XJ, that I just bought has a broken piston. I have always wanted to have a stroked engine and figured what better time than now. My goal is to increase torque and still have a daily driver that will be offroad maybe 20% of the time. I will use this all the time and have to take emissions every 2 years. They do not put a sensor up my exhaust here they plug into the OBDII and take a reading.

So I had a few questions before I attempted to have this done.


What about emissions?
Does the computer have to be reprogrammed?
What about fuel injectors?
Anything else I should know about making my XJ a stroker?
What do I have to change after putting in a Stroker?

I was thinking of going with something like this:
I am sure that you are familiar with it.

4.6L Low-buck, low CR "rockcrawler"

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Silvolite UEM-2229 +0.030" bore pistons
Increase piston dish volume to 30cc
8.75:1 CR
CompCams 68-115-4 192/200 degree camshaft
Ported HO 1.91"/1.50" cylinder head
Mill block deck 0.035"
Mopar/Victor 0.043" head gasket
0.058" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
240hp @ 4700rpm, 315lbft @ 3000rpm


I have been considering changing out the pistons for the kbb ones so I can use 4.0 rods though.
I would like to achieve a low DC so as to use pump gas though. Is there another recipe that might be better? I am trying to not spend a ton of money and have a daily driver stroker.

Thanks

[Cheromaniac]

The "rockcrawler" is a nice recipe with great low rev torque for good gas mileage, and the low CR will allow the use of 87 octane. It's a win win for a daily driver Jeep but if you're on a smaller budget, you might want to consider the "poor man's" recipe that I have in my Jeep.

4.6L "poor man's" stroker

Jeep 4.2L 3.895" stroke crank
Jeep 4.2L 5.875" rods
Sealed Power 677CP +0.020" bore pistons
9.25:1 CR
Stock 4.0 HO camshaft
Ported HO 1.91"/1.50" cylinder head
Mopar/Victor 0.043" head gasket
0.088" quench height
Ford 24lb/hr injectors with stock 39psi FPR for '87-'95 engines, stock injectors with stock 49psi FPR for '96 and later engines
248hp @ 4900rpm, 303lbft @ 3500rpm

With my homebrew CAI, modified Mustang 65mm TB, TB spacer, '01 XJ intake, Borla header (modified with 3" outlet), and custom exhaust, my stroker put down the HP/TQ numbers in my sig. which are equivalent to 248hp/311lbft at the crank (slightly better than recipe numbers). As long as the outside temp. is not higher than 90*F, it'll run on 87 octane without pinging. Gas mileage is fantastic.
I'm using the stock computer with Ford racing 24lb injectors and a homebrew MAP adjuster set at 5.25v.

[qualm]

Thank you for that. I guess I am more concerned with what will happen after I put a stroker in my Cherokee. Forgive me for my newbness. I am just wondering if I will have emission troubles? I live in the States and here it is a big deal that I be able to pass emissions. I see that you used a homebrew for your MAP. How exactly does that work? I know that you adjusted your computer to accommodate for the extra cubic inches, but will that adjustment be significant enough to not allow me to pass emissions? They plug into my computer to check it's readings. Mainly for how efficiently it's burning gas I think. How fantastic is your gas mileage?

What else should I be concerned with? When I figure this out I will decide what kind of stroke to do. I know that my stroke recipe will determine what I need to do in the end, so I was giving the "4.6L Low-buck, low CR rockcrawler" as an extreme of what I will do.

Also I noticed on your "poor man's" that you have a 0.088" quench height. Is this OK? From what I have been reading here they say to have it around .050 or so. That's kinda why I chose to do "4.6L Low-buck, low CR rockcrawler".

I was comparing your "poor man's" specs to the stock 4.0 specs and it looks like the engine gains about 80ftlbs of torque at the flywheel. Is this true?

[lafrad]

If you have a catalytic converter on the car that is in good working order, and good O2 sensors... any stroker recepie will have no trouble with emissions.

The ONLY thing you can do to screw around with it is put too "big" of a cam in there to cause random misfires and crap idle.

I have a 10:1 CR stroker with a mild cam, new Random Tech cat and new O2 sensors and it passes wisconsin emissions tests with flying colors. It actually runs quite a bit CLEANER (by smell and soot levels in the tailpipe) than the original 4.0L did.

[lafrad]

PS: don't be afraid of 9.0 or 10.0:1 CR. I just installed the cam "straight up" (I retarded the cam 4* with an adjustable timing set, because the cam had 4* advance ground in).

It has NEVER had ping, on any fuel I have run. I usually fill with 89 or 93, as the price difference at the local gas station is only about 0.10 a gallon... an extra buck a tank is worth the peace of mind. On hiway trips I'll use 87 exclusively. hiway cruise is always easier on the engine than fart'n around town and/or commuting.

[gradon]

In MD, if you have a 96 or newer vehicle with obd2, you pass emissions if the check engine light is off(and sufficient data stored in the pcm--no recent clears) and fail if the check engine light is on. It doesn't have anything to do with measuring emissions anymore unless you have a 95 and older.

[qualm]

In MD, if you have a 96 or newer vehicle with obd2, you pass emissions if the check engine light is off(and sufficient data stored in the pcm--no recent clears) and fail if the check engine light is on. It doesn't have anything to do with measuring emissions anymore unless you have a 95 and older.

Thanks. This is what I was looking for. This was how I passed emissions last time. No smog test, they just plugged into the OBDII port and I was not sure what they were checking for.

PS: don't be afraid of 9.0 or 10.0:1 CR.

I am not so much afraid of this. Premium gas is not that much more expensive.

[qualm]

What about the 4.6L "poor man's" stroker and the 0.088" quench height? Is this ok? I thought it was suppose to be around .05?

I was comparing your "poor man's" specs to the stock 4.0 specs and it looks like the engine gains about 80ftlbs of torque at the flywheel. Is this true?

[Cheromaniac]

Thank you for that. I guess I am more concerned with what will happen after I put a stroker in my Cherokee. Forgive me for my newbness. I am just wondering if I will have emission troubles? I live in the States and here it is a big deal that I be able to pass emissions.

Emissions shouldn't be an issue. My stroker runs cleaner than my old 4.0 ever did.

I see that you used a homebrew for your MAP. How exactly does that work?

Go to http://www.angelfire.com/my/fan/MAP_adjuster.html for details.

I know that you adjusted your computer to accommodate for the extra cubic inches, but will that adjustment be significant enough to not allow me to pass emissions? They plug into my computer to check it's readings. Mainly for how efficiently it's burning gas I think. How fantastic is your gas mileage?

The bigger 24lb injectors are what compensated for the extra cubes. I used the MAP adjuster to fine tune the A/F mixture to where it needed to be.
Gas mileage is better than it's ever been in my Jeep's 18 year history. Around 19mpg city, 23mpg at 75mph cruise, and 26mpg at 65mph cruise.

Also I noticed on your "poor man's" that you have a 0.088" quench height. Is this OK?

Not an issue. I'm using the hottest grade Champion RC12LYC plugs and can still run 87 octane in sub-90*F weather.

I was comparing your "poor man's" specs to the stock 4.0 specs and it looks like the engine gains about 80ftlbs of torque at the flywheel. Is this true?

I went from 193hp/240lbft crank bone stock to 248hp/311lbft crank with the 4.6 stroker in conjunction with other supporting mods (CAI, larger TB, TB spacer, '01 intake, header, downpipe, exhaust, dual electric fans, 24lb injectors, MAP adjuster).