Noogles

iTrader: (-1)

I was sitting down having lunch with my Engine builder and started thinking about doing a long rod 2.0.

Could you use a stock crank, 162mm rods and 2.3 stroker pistons?


The 12mm increase in the rod length would be accomodated by not using the 12mm longer crank and stroker piston.

althemean

iTrader: (5)

Thats the same thing as the 2.1L destroker isnt it? (granted this is done on the 4G64 block)

2.1L specs: 162mm rod::88mm crank (stock)::87mm pistons (stock bore 85mm)

What is the piston size for a 2.3L? Also...correct me if I am wrong but isnt the piston wrist pin located higher up on the piston on these long rod motors as well?

Noogles

iTrader: (-1)

no the only motor that uses a modified piston is the 2.3 stroker's. the wrist pin is moved deeper into the deck to accomodate the longer stroke and stock deck height.

No need to modify the piston on the 2.1 because it has a stock 88mm crank but 12mm taller deck.

althemean

iTrader: (5)

you're right. I forgot that little fact

EVO8_PR

iTrader: (5)

You could also use the stock 4G63 block with stroker pistons and 156mm rods. This combo would give a 1.77 rod ratio.

Steve_P

iTrader: (5)

I've seen a lot of dyno tests on NA engines where they keep everything the same but make huge change in rod ratios, going from theoretically horrible to theoretically excellent, and power gain is 1-2% on a 600+ HP engine. I don't think it's worth the attention it gets.

althemean

iTrader: (5)

It has more to do with revs that the engine can handle rather than producing more HP from just a change in rod ratio. Bigger rod ratio=less side loads and slower piston speeds. The lower piston speeds theoretically allow longer dwell times so the turbo has a little longer to fill the cylinder at the bottom of the stroke. This is my understanding of it anyways....

joeymia

iTrader: (6)

you would have to use 6mm longer rods not 12mm...

Steve_P

iTrader: (5)

The theory is correct, and I'm sure valid because there are gains, but it only equals 1-2% in the real world on a NA engine. I would expect turbocharged to be less. Several well respected big name engine builders say that on the top ten list of important things rod/stroke ratio is #105- not important. If you're building a nascar engine I'm sure it's important to get that last 10 hp; otherwise I would invest time and effort elsewhere.