I know I sound like a geek, and its kinda late to ask now that my rebuild is well underway, but if you had to make a guess, what kind of performance gains would you expect a long rod 225 to make over a standard 225? 1-3%, 5-10%? I realize it depends on a lot of other factors, but the bills are piling up, and I was looking for some "moral support" now that I'm in too deep to pull out... No regrets, just need some encouragement.

I'm using the Erson 270 cam, super six and Dutra Duals, and compression should be around 9:1. I'm shooting for 200-225 h.p., and hoping the "long rod" aspect will clinch that. Any thoughts from the experts?

_________________
vm

If you have the same compression ratio and all other factors, I would be surprised if it were more than 3%. But, 3% is 5-8HP, which is worth something.

Lou

_________________
Home of Slant6-powered fun machines since 1988

With what you've got into it you should make your target range without a problem, a carter BBD might make things a bit restrictive, but that can be changed later when you refill your wallet in the future.

-D.Idiot

If you doint run out of money a little bit of head work can make a lot of differance. I race a long rod engine but it is race engine different than your setup but still the head is where the power gain is. Thanks Ron Parker










It Aint Over Until I Win

I have run a long rod on the street and strip for years. I am still not convinced that there is any advantage to it other than it makes the engine incredibly resistant to detonation.

Long rod supposedly reduces friction.

Short rod promotes faster cylinder filling.

Tomayto, tomahto.

_________________
Official Cookie and Mater Tormentor.

Thanks, guys. Just what I needed. Onward and upward (with the credit card balance, that is!)!

_________________
vm

The main advantage to the long rod combo is the lighter piston / thin rings, this allows the long stroke 225 to rev a bit easier. I feel that the combo is also easier on the bottom-end bearings due to less piston mass, less ring friction and less rod deflection.

On the down side, the 2.2 piston is not as strong as the big, heavy, steel expansion strut factory "slug" and the top ring is up a lot higher & closer to the heat with the 2.2 piston.

In general, I have less bottom end trouble with long rod motors but more piston problems.
The piston problems are directly linked to the higher compression ratios you can get "right out of the box" with a long rod engine but as noted, the engine is more resistant to detonation.
So... don't let it ping or run lean and you are fine. If you do get into detonation / lean-out, an off the shelf 2.2 pistons won't last long.
DD

And, if your engine guy tells you that 2.2 pistons will only hold a 125 shot do not tell him he's full of shyt.

_________________
Official Cookie and Mater Tormentor.

Go forged flat-tops or dished slugs for 2.2. Don't get ones with high silicon content (hyper....) these break like glass.

People with 2.2/2.5 routinely exceed 200-300HP level on turbocharging over at turbododge.com. Very few is running race-only 500HP levels.

Cheers, Wizard

I cannot speak directly at automotive engines, but I know that long rods do translate to more torque in a motorcycle engine. Also less defelction helps the big end bearings live longer. Not sure if it translates for all engines, but do not see why it would not...
Slanted66