2.0 Pistons in a 1.8

[Berek]

Ok in a recent post i was told (if i did not misunderstand) that the difference in the displacement had to do with the head. So with that in mind....Can I put 2.0 piston and connecting rods in the 1.8 without having to bore the cylinders? I asked this of a friend of mine and he suggested that if I did that to go ahead and use the 2.0 head? It made no sence to me but then neither does the displacement explaination that I have probably misunderstood. Any one have anything on this?

[narfire]

Difference is in the stroke, the 1800 block is shorter. Both engines have 84mm pistons. Now I have no idea if the valve cuts are different though.

[Schnauzer]

Valve cutouts are bigger and deeper on the 2.0L but a bigger issue is that the distance from the center of the wrist pin to the top of the piston is greater on the 2.0L pistons. We just did my Son's 79 carb'd 2000 with a 1.8 head which required using the 1.8 pistons. Fantastic conversion by the way. Runs great. Thanks to Mark at Allison Automotive.

Jim

[Berek]

Valve cutouts are bigger and deeper on the 2.0L but a bigger issue is that the distance from the center of the wrist pin to the top of the piston is greater on the 2.0L pistons. We just did my Son's 79 carb'd 2000 with a 1.8 head which required using the 1.8 pistons. Fantastic conversion by the way. Runs great. Thanks to Mark at Allison Automotive.

Jim

I'm confused. So did this in essence did this make a 1.8 stroker? so if that be the case installing a 2.0 crank would do the same thing on the 1.8?

[bobplyler]

The only reason for doing this is if you already have the pistons. And the piston pin height may not be right. It won't make the engine any bigger.

[maytag]

Valve cutouts are bigger and deeper on the 2.0L but a bigger issue is that the distance from the center of the wrist pin to the top of the piston is greater on the 2.0L pistons. We just did my Son's 79 carb'd 2000 with a 1.8 head which required using the 1.8 pistons. Fantastic conversion by the way. Runs great. Thanks to Mark at Allison Automotive.

Jim

I'm confused. So did this in essence did this make a 1.8 stroker? so if that be the case installing a 2.0 crank would do the same thing on the 1.8?

changing the pistons does not make a "STROKER". a "stroker" is created when you increase the stroke.
I'm not sure what would precipitate the use of 1800 pistons in a 2000; I've never measured, but it sounds like there must be a difference in compression height of the pistons.

so lets return to your original post, and try to "unconfuse" you.

You cannot use the 2.0 rods and pistons in the 1800 block. they are too long. it might be possible to use the 2.0 rods with custom pistons with a short wrist-pin-to-piton-top height. I say "MIGHT". Similarly, it "might" be possible to use 2.0 pistons with other rods. but you can't use the pair, because they'll exceed the height of the cylinder.

so: let me ask you a different question: what are you trying to do, exactly?

[FiatMac]

Ok in a recent post i was told (if i did not misunderstand) that the difference in the displacement had to do with the head. So with that in mind....Can I put 2.0 piston and connecting rods in the 1.8 without having to bore the cylinders? I asked this of a friend of mine and he suggested that if I did that to go ahead and use the 2.0 head? It made no sence to me but then neither does the displacement explanation that I have probably misunderstood. Any one have anything on this?

The 2.0 and 1.8 pistons can be used interchangeably in either engine. The compression is virtually unchanged. The difference in compression height between the two pistons offsets the valve pocket size difference. See calculation below (right click on image and select view image to see the whole image- 1.8 liter calculation is on the far right).

The 2.0 Liter connecting rods are too long for the 1.8 liter block as has been pointed out and will result in piston interference with the head.

There is no reason to go with the 2.0 liter head on a 1.8 liter engine if you install 2.0 liter pistons. In fact doing so will drop the compression ratio to about 7.6 due to the larger combustion chamber volume.

[maytag]

so, let us help you berek: what are you trying to accomplish?

[Berek]

so, let us help you berek: what are you trying to accomplish?

Thanks for the replies. Ok in short I have to fix my 75 1.8 in reading some of the post I suppose I was getting confused. I have had a habit of always trying to find ways of modifying with junk yard parts. My thought was initialy that as I will have to rebuild and am poor, that maybe I would get more bang for the buck if I found some thing that would interchange internaly to increase compression and get better performance for minimal if not the same price. When I seen the post about the 1.8 pistons and the 1.8 head inconjunction (I assume) with the 2.0 crank I assumed it must be some kind of stroker combination though it only made sence to me if there was a difference in the stroke of the 2.0 vs the 1.8 crank. I set up some ford strokers way back and they were junk yard combos i was hoping for the same thing here, but I am seeing that is not the case. Sorry I over think sometimes lol Do you have any suggestions for anything this way?

[djape1977]

just get yourslef a set of euro-spec 1.8 pistons

[maytag]

well, I ALWAYS look at repairs as an opportunity to upgrade. but it depends on what is wrong to begin with, and what your real budget is.

What MUST be replaced in your motor? What's wrong with it?

[131]

The 2 litre crank does provide a longer stroke than an 1800 crank, the rods are longer and the block is taller. A 2 litre crank in an 1800 block, even with the shorter 1800 rods, is going to have the pistons coming out the top of the bore. Even if you had lower compression height pistons, there wouldn't be enough room above the gudgeon pin for a ring pack and the longer crank throw would pull the piston too far down the bore as well. If it could be done, there'd be lots of 1800 strokers around.

[Berek]

well, I ALWAYS look at repairs as an opportunity to upgrade. but it depends on what is wrong to begin with, and what your real budget is.

What MUST be replaced in your motor? What's wrong with it?

I sucked two valves on the #3 piston. The valves got pushed through the piston. The head was so badly battered that it can not be re seated. I will most likely just get a #3 do a ring job and replace the head. That would be the most cost efficient repair. I don't really have a budget i live pay check to pay check. I will order some of the stuff hopefully next week as I had over time this week and some one to watch the kid. I am hoping for at least the piston and rings or bearings.

[Berek]

Thanks guys for all the input. I have it down now.

[vortspeloce]

Even if you had lower compression height pistons, there wouldn't be enough room above the gudgeon pin for a ring pack and the longer crank throw would pull the piston too far down the bore as well. If it could be done, there'd be lots of 1800 strokers around.

If I remember right, the 2ltr crank won't do a full revolution in the 1800 as the counter weights touch the 1800 block casting (possibly the bottom of the bore - can't remember it was 6mths ago). With the 1800 in standard form the pistons are right up on the deck. I measured circa <1mm clearance on mine. The 2ltr stroke would certainly have the pistons impregnated in the combustion chamber. I have not thought hard enough about if a stroker (longer rods only) would really be possible. 2ltr rods in an 1800 with F1 style pistons? Center to center we have 136 vs 145 == 9mm. Could the piston CH be safely lowered 9mm? Possibly with a forged set? I have not measured from the top of the pin to the deck. Anyway, some food for thought!