tuning 4.6l

[herbiehind]

hey all ;
i'm new (noob) and could use some patience .
i plan on a 4.6 or there about . i read up on dino's and i like the poor mans' but i'd like the quench smaller so milling or 4.0 rods will be the way and i'd like .030 over .
so i've got the crank and i've got 4.2 rods if i go that way .
my main question for you guys is will i need to go with an adjustible map or some way to tune the fuel air mix? in your experiences does the 4.6 tend to run lean or rich on the stock cam? i may run a stock cam . if i keep compression to about 9.5 or below can i run 91? and stock cam or would aftermarket comp cam or comparible longer duration be better? trying to avoid all kinds of crazy tuning stuff . not a big fan of tech stuff .
thx .

[Cheromaniac]

In my '92 XJ I'm running the stock computer, stock FPR, FRPP 24lb injectors, and a homebrew MAP adjuster set at 5.3v. If I leave the MAP voltage at the stock 5.0v the engine runs lean.
You could build your stroker like mine but with a 0.030" overbore and 0.010" milled from the block deck. That would put the SCR at 9.5:1 and the quench at 0.078". I run mine on 87 octane from November-March when the outside temp. is below 100*F and switch to 91 octane in the hotter months. That's with stock Champion RC12LYC plugs but I'm also running a 180* t'stat and a Flowkooler water pump so the engine runs as cool as a cucumber.
The advantages of using the stock cam are that you can keep the stock valve springs/retainers so less worry about cam lobe/lifter wear, better bottom end torque, glass smooth idle, higher idle vacuum, and slightly better gas mileage. I'm very happy with it.

[montelibre]

With my ´97 XJ 4.6 Stroker I ran fine without any adjustment, with 24 lb/hr ford injectors and stock computer.

[SilverXJ]

What is your AFR in WOT with the 24 lb injectors?

[montelibre]

Currently I have the motor disassembled.
The AFR in WOT do not know exactly, but must be rich. I did severaral test with a Scan tool and the lambda value is about 0.8-0.9 volt (O2 sensor output voltage).
Values above 1 volt O2 sensor output indicates rich.

[herbiehind]

In my '92 XJ I'm running the stock computer, stock FPR, FRPP 24lb injectors, and a homebrew MAP adjuster set at 5.3v. If I leave the MAP voltage at the stock 5.0v the engine runs lean.
You could build your stroker like mine but with a 0.030" overbore and 0.010" milled from the block deck. That would put the SCR at 9.5:1 and the quench at 0.078". I run mine on 87 octane from November-March when the outside temp. is below 100*F and switch to 91 octane in the hotter months. That's with stock Champion RC12LYC plugs but I'm also running a 180* t'stat and a Flowkooler water pump so the engine runs as cool as a cucumber.
The advantages of using the stock cam are that you can keep the stock valve springs/retainers so less worry about cam lobe/lifter wear, better bottom end torque, glass smooth idle, higher idle vacuum, and slightly better gas mileage. I'm very happy with it.

those attributes of the stock cam are why i lean that way . thx for the info on the map sensor i guess dinos adj. sensor is the way . and i can get a tap in afr meter so no bungs to weld and widebands to buy . still i'd like the quench around .060 . i read it keeps temps and pinging at bay . dished pistons i guess .

[herbiehind]

With my ´97 XJ 4.6 Stroker I ran fine without any adjustment, with 24 lb/hr ford injectors and stock computer.

what was your quench and cr ?

[herbiehind]

interesting , dino indicates his went rich at wot in his article . you running stock cam ? this is good to know it's safe . thx all for adding this is fun stuff . found a 96 -98 motor for 200.00 78,000 mls. so hopefully some good reuseable parts . now to find a good machinist in attleboro ma area .

[Cheromaniac]

Currently I have the motor disassembled.
The AFR in WOT do not know exactly, but must be rich. I did several test with a Scan tool and the lambda value is about 0.8-0.9 volt (O2 sensor output voltage).

You need the motor to be rich at WOT. A lambda value of 1.00 is equivalent to an A/F ratio of 14.7:1 which is too lean for WOT. A lambda of 0.90 is equivalent to a 13.2:1 AFR and a lambda of 0.80 is equivalent to a 11.8:1 AFR. Sounds like your lambda values are good and safe. Ideally you'll want them in the 0.85-0.90 range at WOT.

[Cheromaniac]

still i'd like the quench around .060 . i read it keeps temps and pinging at bay . dished pistons i guess .

I wouldn't get too hung up on the quench. Mine is 0.088" and I'm running 87 octane with the hottest Champion plugs. Just make sure you smoothen the combustion chambers and piston dishes so there are no sharp edges to cause preignition, make sure your cooling system is up to scratch (I'm running a stock 2-core HD radiator, 180* t'stat, Flowkooler pump), and make sure the engine doesn't run lean. Those are far more important fundamentals to get right than a tight quench.

[herbiehind]

still i'd like the quench around .060 . i read it keeps temps and pinging at bay . dished pistons i guess .

I wouldn't get too hung up on the quench. Mine is 0.088" and I'm running 87 octane with the hottest Champion plugs. Just make sure you smoothen the combustion chambers and piston dishes so there are no sharp edges to cause preignition, make sure your cooling system is up to scratch (I'm running a stock 2-core HD radiator, 180* t'stat, Flowkooler pump), and make sure the engine doesn't run lean. Those are far more important fundamentals to get right than a tight quench.

what pistons did you run? i like the ideas behind the 4.0 rods but the 400.00 + for the pistons is big money and could go toward rollers .

[SilverXJ]

You could spend the $400 on pistons now and change to roller rockers later. Rockers are a lot easier to change down the line than pistons.

[montelibre]

My quench was approximately 0.075" (I measured deck clearance about .032" more MLS Victor reinz head gasket 0.043"). The CR about 9.9 to 1. I ran with 95 octane (petrol in Spain have 95 or 98 octane).

[herbiehind]

You could spend the $400 on pistons now and change to roller rockers later. Rockers are a lot easier to change down the line than pistons.

wow , yeah i didn't consider that .

[herbiehind]

My quench was approximately 0.075" (I measured deck clearance about .032" more MLS Victor reinz head gasket 0.043"). The CR about 9.9 to 1. I ran with 95 octane (petrol in Spain have 95 or 98 octane).

damn , i remember the good ole days of high octane