Major Question: Can I put a 2004 factory supercharger on a non supercharged 2004 4.2 motor???

My 2004 XJR supercharged 4.2 engine is bad, I have a spare 2004 non supercharged 4.2 engine is why I am asking.
I know about the variable camshaft timing, I can switch the cams, sprockets and chains etc.

 

Hi Phydeaux1,
I don't think that would work very well. The SC engine has deliberately reduced compression ratio to compensate for the forced induction. I think the NA engine would have serious detonation problems if you tried to supercharge it.

PM

 

Same bore & stroke, but the NA has raised features on the piston crowns that the supercharged pistons do not have. Might have made more sense when 110 and even 130 Octane gas was available.. Present-day so-called "high test" not so much!

By the time you have swapped 8 pistons, (rings, gudgeon pins, rod bearings... yadda yadda,,,) you'd probably be just as well-off to rebuild your supercharged motor - or another one like it.

 

Yeah, completely different internals in the SC engine. It's not just a bolt-on by any means.

 

Yep, completely different. Additionally to the differences already mentioned, the supercharged engine has a piston colling by oil jets that the n/a engines does not have.

Best regards,

Thomas

 

Ok, thanks for the replies.
RJ

 

You could also simply forgo the blower.

The NA 4.2 has better 'real world' performance (not 'racing') as a daily-driver anyway.

- Less 'total' power at peak, but faster response off the line and in medium speed commuter-trafffic sword fights.

 

1000% wrong. The whole point of a roots blower is immediate torque. The supercharged engine is better at every vehicle and engine speed and it's not even close

 

Drinkin' too much advertising hype kool-aid, Pilgrim.


The Supercharger maker has done a good job. JLR has integrated it well. Mostly if "JFW" with relatively little extra maintenance need nor expense.

I've no quarell with it.

That said, neither is is magical, free money, or better sex.

For most daily-driver situations NEITHER an "NA" nor "blown" AJ Vee engine is asked for but a small fraction of available power.

WHEN in that majority-of-the-time 'range' - 'ordinary' driving, dictated by traffic, road conditions, weather, and other drivers - the normally aspirated AJ Vee is a skosh more responsive.

BOTH are limited by electronics to a top speed about DOUBLE the legal maximums in either case.

That's not "theory", lab tests, racing, hill climbs, 'alone on the road to go and PLAY'.. or wishing, hoping, day-dreaming about any or all of the above... plus better sex, and free money, whilst we are wishing.

It's just how they are when operated in amongst the usual external constraints.

Marine or aircraft recips? Long hours at steady power - altitude gradient? Dif'rent story.
Engine-driven plus exhaust driven for "Turbo Compounding" if you please.

 

Not sure what all that unrelated text was all about, but having driven both, the supercharged motor is just superior in every situation.

 

I'm happy your environment - and lifestyle - supports that.

Make parts and upkeep a tad cheaper for the easier to service NA's I prefer.. more especially with RWD "only" vehicles on snow and ice..