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Displacement Changes


Redfox340

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I'm posting this because it's late and I'm second guessing myself.

Can you change the displacement (literage) of a motor with just a top-end motor swap?

 

- Erik

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...top-end motor swap

 

Top end eh? You mean heads, intakes, and leave the block the same? The only way to increase displacement is by increasing (or decreasing) the bore and/or stroke.

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I'm posting this because it's late and I'm second guessing myself.

Can you change the displacement (literage) of a motor with just a top-end motor swap?

 

- Erik

 

No. Duh :roll:

 

 

Only kidding man :wink:

 

Robby

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That's what I thought.

There's been a newbie back-lash against me over on a L-Body forum about a 3400 SFI swap into a Beretta.

A guy wanted (as I interpreted) to go to a 3100 to 3400; told him what's needed and we shot down by "older" member.

 

You really need to read before you try to post good info. The 3400 swap does NOT need the SFI or the ECM it will work on the Multiport fuel injection... because nates running a 3400 5 speed in his 92 GT and hes running high 14s and thats on the multiport code..

 

Ok... so... is this correct?

Are we even on the same page here? :?

 

- Erik

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Sounds that guy is talking about a 3.1L to 3400 top end swap. And, since the motors share the same sensors you can use the ECM from the 3.1L, it will just be Multiport not Sequential Port.

 

Robby

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Sounds that guy is talking about a 3.1L to 3400 top end swap. And, since the motors share the same sensors you can use the ECM from the 3.1L, it will just be Multiport not Sequential Port.

 

No, he'll take the 3.1L MPFI ECM and stick it the injectors into the recently swaped 3400 SFI and change it to a 3400 MPFI.

 

- Erik

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If the combustion chambers on the new heads were bigger, then displacement would technically be increased by a small margin,(a few cc's) but at the same time, you'd go down some points on compression.

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Sounds that guy is talking about a 3.1L to 3400 top end swap. And, since the motors share the same sensors you can use the ECM from the 3.1L, it will just be Multiport not Sequential Port.

 

No, he'll take the 3.1L MPFI ECM and stick it the injectors into the recently swaped 3400 SFI and change it to a 3400 MPFI.

 

- Erik

 

Oh, okay, I see, I misunderstood. :oops: :oops:

 

Robby

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If the combustion chambers on the new heads were bigger, then displacement would technically be increased by a small margin,(a few cc's) but at the same time, you'd go down some points on compression.

 

No, the piston is not moving any more or less. You will lower compression this way, but you won't be changing how big the bore is, or how far the piston will travel.

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If the combustion chambers on the new heads were bigger, then displacement would technically be increased by a small margin,(a few cc's) but at the same time, you'd go down some points on compression.

 

No, the piston is not moving any more or less. You will lower compression this way, but you won't be changing how big the bore is, or how far the piston will travel.

 

Displacement would be measured buy how much of a fluid it would take to fill a chamber, in this case the cylinder bore. If the heads with larger combustion chambers will hold more fuel & air, the cylinder will be bigger. Hence, SLIGHTLY more displacement. It's a moot point, like I said before because it would only be a few cc's.

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Sorry, displacement means just that. Piston and head cavity shape can complicate compression ratio (CR) calculations but does not affect those for displacement. Displacement is literally the volume swept (displaced) by the piston.

^

That is found here. It is a moot point and not trying to start an argument but I don't want people mis-informed.

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