And Penny just keeps on changing...

[Steve1968LS2]

Originally Posted by ohcbird

Greg-
It will depend on the breathing characteristics of the engine. The better the heads / chamber / cam are, the easier it is to go under-square.

The easy answer is that that fast acceleration & decelration (for a given RPM) of the piston will help produce more power across the band. The hard part is getting the combo right...but LS engines are almost too easy now.

Todd- Like Steve said, there are lots of US engines being produce now, especially inline engines. I know it sounds counterintuitive, but they are actually easier to produce and balance as well.

Back to your regularly scheduled Penny update...

What he said.. lol

It use to be a bigger issue that it is today and typically you were better off being over-square than under. Today, with the right parts it's not such a big deal. I feel my ratio of .977 is pretty damn close to square. Imagine if you had a 4.165 bore and 4.625 stroke. Would i have ran a 4.200 crank if I could have? Yea, but they don't so I decided I would rather have more displacement rather than move to an over-square (4.165 x 4.125).

[ohcbird]

Todd-
Yes, for the same heads / cam combo & just a stroke change, that's generally true. Due to most new LS heads & 4 valve heads, that isn't necesarily the case anymore. Regardless, the engine is always about the combo rather than the resume of it's parts.

[Steve1968LS2]

Originally Posted by GregWeld

Nowhere in Steve's math did he mention ROD RATIO.... and I always thought that this was important. I've actually been thinking of de-stroking the 427 because it has such "bad" rod ratio (4.125 bore - 4.00 stroke - 6" rod)

Is this no longer an issue with the taller decks of the LSx ?

Steve --- LOVE the updates -- like Eric said - it's fun to live vicariously.

It is.. but again after talking with Brian Nutter at Wiseco he feels his piston design will be good to go. My rod choices consist of one size. 6.125.. At least from the Lunati catalog that I'm dealing with.

We will see if they are right

Originally Posted by Vegas69

Normally it's more low end torque and slightly less high end horsepower.

Yep.. and to be honest that's really goal. Personally I didn't want anything bigger than a 440, but the 454 just sounds so damn sexy.

I'm going to cam it down so that it still has a great street idle. I guess you could say that I'm going to size the cam like the engine is a 440 and the extra displacement will help smooth stuff out. I would be happy with 650/600 but after running this 440 last week I think it might be more.

[ohcbird]

A few good cubes are always agood thing.

[Vegas69]

I was considering doing an undersquare engine as well. I have a bore size of 4.280. My block will take a 4.375 stroke. Ultimately my engine builder didn't feel it was a good trade off in power vs. cost and longevity. I had to ask myself, why don't you see them in any high performance application from the factory? The only conclusion I had was longevity and warranty. I ended up with a 4.25 stroke with a 6.385 rod. Another thing is big block stuff is heavy and they are harder to turn rpm with. Adding more low end torque and less high end hp didn't make sense for me where it may very well for you. I love this stuff.

[Steve1968LS2]

Originally Posted by ohcbird

A few good cubes are always agood thing.

Never met a cube I didn't like. lol

I figure if Jackass and Blue Bomber can hook up 700-800 hp then I can hook up 680..

And the lack of a weight penalty is a bonus...

[Steve1968LS2]

Originally Posted by Vegas69

I was considering doing an undersquare engine as well. I have a bore size of 4.280. My block will take a 4.375 stroke. Ultimately my engine builder didn't feel it was a good trade off in power vs. cost and longevity. I had to ask myself, why don't you see them in any high performance application from the factory? The only conclusion I had was longevity and warranty. I ended up with a 4.25 stroke with a 6.385 rod. Another thing is big block stuff is heavy and they are harder to turn rpm with. Adding more low end torque and less high end hp didn't make sense for me where it may very well for you. I love this stuff.

Because the factory uses inferior parts for the most part.. they certainly don't use forged cranks and all the other goodies that make a reliable under-square engine possible.

You combo was just barely under-square with a ratio of .978 ... I don't think it would have been a huge issue so long as you have good parts, especially the crank.

And you're right, there's a big difference between a big-block and an LS.. seems like you can get away with more on the LS side.

[Steve1968LS2]

Well, it doesn't feel like it but progress is being made.

The underside is scraped and the new Wurth stuff should be on there by tomorrow.

With any luck I should be picking up the rearend housing from powder this week as well, then we can put the rear back together and get her rolling again. Found that he axle tubes were pretty warped from the 3-link brackets so Currie cut off the ends and welded on new ones.. straight.

Parts are moving for the 460 cube RHS LS engine, biggest delay will be the 4.250 Lunati crank which is two weeks out. That's the only delayed part though.

Cam selected is a 247/261 .624 114 LSA stick.. Any guess as to power?

Should be good to go for having the car done by April.. knock on wood.

The LM clutch is over at Centerforce getting refubed (figured I might as well since it's out)

The oil cooler system is also in progress getting all hard lined up. The Setrab 925 fits perfect. This is being done at Fast Eddies Fabrication in Orange, CA.

[scherp69]

Steve...is that an autorad setup? Your car is amazing

[Steve1968LS2]

Originally Posted by scherp69

Steve...is that an autorad setup? Your car is amazing

Yea, there are more pictures earlier in the thread. Of course we're modifying it for the oil cooler deal.

The nice part is how much radiator is still uncovered even with the huge cooler.

And thanks for the compliment on the car.. it's a team effort.