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# Need help with Cylinder Size on 4.8L LS Gen 3

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as the title implies Im having trouble calculating my cylinder size for my Gen 3 4.8L LS engine, stock pistons, crank, heads etc.. I keep getting different answers so I must be converting something incorrectly, or when I put my number into the Cylinder Volume tab in HP tuners it keeps changing it slightly. I know that changing these values affects my VE table so I want to get it correct. Does anyone on here have a 4.8 with HP tuners where it says what the cylinder volume is? Or can someone walk me through the process of finding the correct volume? as stated it is a 4.8l, would I just divide this by 8? or does it not include the area of the cylinder head? any help is greatly appreciated

4.8L

293 (or 294 depending on where you read from) Cubic Inches

stock bore: 3.78 inch bore or 96.01mm

stock stroke: 3.267 inch or 83mm

I know this may seem like a stupid question but i really am trying to understand this and do not want to get it wrong, thanks in advance! really loving all the help im getting here, you guys are awesome!

Simple answer is 1/8th of the engine capacity.

More accurate is 36.6625 cubic inches, or 600.9 cc, from the dimensions you gave and assuming no overbore.

Cylinder size, or to be more accurate swept volume, is the cross sectional area of the bore times the stroke - or (b^2)/4*pi*l, where b is the bore diameter and l is the stroke.

No offence intended, but this is barely high school stuff - not sure how you can get different answers.

Thank you so much for your quick reply! And I know this is high school stuff, that's why it was so embarrassing to post that Haha. And idk how I was getting different answers, I must've been converting something incorrectly or putting a number somewhere I shouldn't have. And no offense taken! It's a silly question and I should expect to get burned on the net at least a little for that xD. I can build a truck from the ground up, including engine, trans and even convert my factory harness to standalone. But math proved to be my downfall, should've paid more attention in school, and definitely need to take some courses in it now that I'm older and can actually focus on it. Thank you again for your help!!

:EDIT: as for the different numbers, I just tried punching those numbers into my HP tuners (36.6625) and it changed the numbers when I clicked elsewhere to 36.6623. Do you think this will make a considerable difference in my tune or should I just leave it?

Cheers!

Internally the ECU has some finite resolution, so there can be a slight rounding. If this is the limit of the resolution of the system then it will have no measurable efffect. Generally we can get away with error of +/- .5%, which would be +/- 0.18 cu in per cylinder. The rounding error you describe (0.0002) is only a 0.00055% error so it is insignificant.

So, don't worry about the software rounding a value when you enter the best value you can determine.

What David said.

Thank you so much guys! Once again, it's fairly embarrassing to be asking such a trivial question, as I do not like wasting peoples time, but I do appreciate you guys getting back to me in such a quick amount of time and clarifying things so that a simpleton like myself can figure it out! Changes have been made and I got my wideband relay and all that jazz hooked up this morning so hopefully tomorrow I should start my logging and trying to rescale my maf

We usually reply within 12hrs (often sooner)

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