This question comes up every once in awhile, and did again in another thread. Rather than replying there I figured I'd make a new thread.

The 2270 number comes from 96mm pistons and 78.4 as the stroke. I'm pretty sure this 78.4 BS came from building motors for a racing class (probably under 2.3l) where people were trying to get as close to the limit as possible (more power).

But the reality is that most 2270 engines are actually just off-the-shelf 78 stroke cranks.

So 2258 is a better general reference term, I'd say it's more representative of what the engine is. But it doesn't roll off the tongue. I've moved to simply referring to them as 2.3l engines.

If you REALLY want to be accurate, the '2270' that I'm assembling right now had a crank 78.26 and a 96mm bore. So really it's a 2266...

So call it a 2270, a 2258, or a 2.3l -- they're all the same idea and none are really all that accurate.

Thanks for the info, Mark! I always enjoy being educated.


I just hoped to call one 'mine' one day

Having said that, "2.3" is nice and succinct.

And since y'all didn't grow up with the metric system, let me help you convert the 2266 milliliter to liter.

2266 ml = 2.266 L


Moving the decimal point, almost as complicated as getting from cubic 1/16th to cubic yards ...

And it's falls in line with the way we talk about stock engines. Nobody says 1971, they say 2.0.

1.7
1.8
2.0
2.1 (2056)
2.3 (2270/2258)

& 2366 = 2.4L

I thought the 78mm was the largest that would spin without machining and something about smaller bore rods?

Factory stock 2.0L is 1971cc not 1975.

Is that long stroke + smaller bore more favorable and longer lasting than a short stroke + large bore motor? (street and hooning around)

I knew when I typed it that I should look that up and make sure I remembered it right.

Thanks for setting me straight, I'll correct it.

I think you're asking why none of these engine combos use pistons larger than 96mm. The answer is cylinder to head sealing. At 96mm things aren't pushed very far beyond stock and are therefore more reliable. If you go all the way to 103mm the cyl-to-head seal is very thin. The only real way to make a 103 work long term is to work with LN Engineering Nickies to retain a suitable sealing surface. They can make a single set with any design, whereas steel cylinders are only being reproduced in that shape.

Even a 78 can take a bit of clearancing in the case. 80 needs a bit more, but it's not precision work.

Most of the engines 2.3 and beyond are using Chevy rods or Type 1 rods. 2.1 and below all use stock Type 4 rods.

Rounding has always been done, manufacturers are the ones that started it and they always round up. The way they get around this legally is the correct size is listed in the owner's manual and a label on/near the engine.
I have an ATV Yamaha 450 really, it's a 423cc (cast right into the block) but they don't call it a 400.
My bug is a T4 2.6L, really it's a hair under 2600cc

To me 2270 is generic for a 78mmx96mm and a manufacturer would call it 2.3L, mainly for promotion, if it was a production engine.

Pretty well every metric measured engine out there isn't exactly the size stated, a cc is a very small measurement compared to cubic inch.



78mm needs a reduced base circle cam and chevy or aftermarket T1 size rods that need to be clearanced slightly.
80mm needs the the chevy rod, a reduced base circle cam and clearancing.

The 78mm crank with T1 style rods is stronger as it has a larger journal (2.165") and won't flex as much as a crank with the smaller 2" chevy (buick) journal.

Even "Chevy" rods is a misnomer, really they have nothing to do with chevy rods, they have a 2" Buick size big end, different length, and different small end (22mm).

Nice displacement calculator here based on bore and stroke.

Mine comes out at 2.368. can I round to a 3.0?

Just put one of these on the engine grill
Funny that the 911 2.4 was only 2.341


I took the 2.0 off the back of mine, and plan on putting a 2.7 badge on the engine lid.

When using this calculator and the information from the Type IV Store for their 2563-190 engine kit I get 2.549.

(78mm Stroker Crankshaft Ct/Wt T1RJ
102mm Nickies™ Performance Billet Aluminum Cylinders)

How do they get to 2563?

With all of this information it seems this would be referred to as a 2.6L and possibly the ultimate Type IV engine for a very spirited daily driver.

Isn’t there a 78.5 crank?

That's what I have in my '67 bug, with the right cam and header around 180hp.
My crank is old school so it's 78.4, 2562cc or 2.6L


78.4mm it's the max using VW T1 rods, all newer cranks are 78mm.