Finding the difference between 3.3 and 4.1 litre???

[Anonymous]

Hey guys.

I own an XF falcon and have just put a reconditioned engine in it.
It had a 4.1L before i got it changed, and went fairly quick.
But now, its sluggish compared to the older engine.
I took it to a carby specialist for a tune and asked him about it, he says that it goes like a 3.3L and nothing like a 4.1L.
He tells me that there is no way of checking wether its a 3.3L or a 4.1L without looking at the crankshaft... is this true?
If not, how can i check it???

Pease help!
Id much prefer the power of a 250!

 

[Anonymous]

Bass freak,
The difference between a 250 and the 200 is the length of the stroke. i.e. piston travel.
to check in car.
Remove all the spark plugs. So that the engine can be easily turned over by the fan.
Put a length of wire( like a cut up coat hanger).
Spin the motor over slowly with the wire down the plug hole in light contact with the piston.
Mark the wire at the spark plug hole when the piston is at the top of its travel.
Rotate the engine slowly, with the wire in light contact with the piston until the piston is at the bottom of its travel. Mark the wire at the spark plug hole in the same position as before.
A felt pen/texta for this marking so it is easy to see.
Now measure the distance between the marks this will give you a rough guide to the piston travel/stroke and will indicate the size of the engine.
Unfortinuately I dont have the spec in front of me but Im sure someone else will have this size.
I can look it up at work.
But this will give you something to do this weekend.
Noel.

 

[addo]

If it goes down about 10 cm, it's a 250/4.1 or about 8 cm for a 200/3.3.

Who rebuilt the motor? A "name" brand reco?

Adam.

 

[Anonymous]

Thanks buddy.
I might have a go at that coat hanger experiment this weekend.

Nah, it's not a name brand company that rebuilt it... it was just an off the shelf exchange sorta thing.

Is there any difference in the block sizes between the 200 and 250ci? ...or is it just the crankshaft thats different (for a higher lift)???

Also, are the cylinder bores the same diameter??? ...If they are, i could just stick a 250 crankshaft in to stroke it up to a 250 couldnt i?

Thanks heaps guys,
Ryan.

 

[xctasy]

The 3.3 has longer rods and a shorter stroke crank. Pistons are higer compression, but the same diameter and height. That's it! No external differences, and 25% difference in torque with no-one else any the wiser.

It would be a clever guy who could change the crank and rods to make it a 250 without changing the pistons. The 3.3 pistons would drive the compression over the 10:1 mark, not what you want on todays pump petrol.

 

[addo]

That said, you could swap in a crank and rods if it's a 200... Maybe with a quick hone and a cheapo set of cast pistons. The 200 pistons might be flat-topped while the 250 are dished. This was true for the earlier ones at least.

More likely is it's a 250 with a poor cam/cam timing.

Cheers, Adam.

 

[Anonymous]

We chucked the pre crossflow 200 out of the Transit and stuck in a alloy 250. WHAT A DIFFERENCE!!!!!!!
200s are gutless and 240s are great.