Mechanic a

looking for I an info on building a lq4 as a square engine 4.0 bore by 4.0 stoke is a square engine good for performance use?

Tuskyz28

What you'll basically have is a 402ci motor. It's plenty of proven results across the board with different heads, cams, and intakes.

Mechanic a

I was wondering more about how will it rev compared to over square and under square. I read that the square engines were used more in industrial uses and heavier trucks. also what about peak rpm and where they make power compared to the stock bore and stoke lq4. I need to change my pistons trying to get around 11:1 and figured might as well do the rods at the same time and I cant decide on whether or not to stoke I definitely am not boring it over

MileHighSierra

Well, an oversquare motor is the most ideal engine for making big power at high RPM. Think of a Porsche engine, like the 3.8 and 4.0's in their 911 GT3RS's. These engines have huuuuge pistons (Big Block Chevy style), and very short strokes. This does 2 things: less rotating mass=less inertia, so it's much quicker to rev and there is additionally less secondary vibration on the crankshaft.

Additionally, big pistons allow for bigger valves, and therefore more airflow. An engine is just a big air pump essentially.

How it will rev is really going to be based upon the weight of your reciprocating mass, i.e, pistons, rods, and crankshaft. If you want a screamer, go with a 5.3, or even a de-stroked LS2 with a 4.8 crank. However, there isn't much point as we are talking about an OHV layout, and you're going to need to go to solid lifter valvetrain. If you like working on your engine a lot, then you're fine. If not, stay far away.


A great reference is the LS7. Big pistons right? But very light con-rods, and a valvetrain built to rev to 7500rpm (well, not without dropping a few valves, right? j/k). It was engineered to make power everywhere in the powerband, will revving very high for a large displacement.

What are your goals? What kind of vehicle is this going into?

Tuskyz28

What's the application the motor is going to be used. How high you can rev the motor is go depend on the camshaft profile and intake mainly...

With a 4 inch crank you'll definitely have mord torque under the curve compared to a stock stroke motor.

You mention industrial... will this be a motor to tow your car to the track or will it be a motor for street racing/drag racing ?

96capricemgr

iTrader: (1)

At the risk of oversimplifying things if you are this fixated on the shortblock you are at risk of missing what really matters.

People fixate on shortblock, and displacement and rod length and crap, then the guy who just buys good heads and valvetrain walks all over them for half the money.

Money spent in the shortblock is some of the most expensive HP you can buy.

Mechanic a

Bright now it is in a 95 camaro with 243s milled 30 to make the compression I wanted and a btr cam but now I have cnc ed ls3 heads and changing the cam and Pistons. Wasn't happy with what I had Aslso has all the standard bolt ons, long tubes, injectors, etc turbo 400 3500 stall 373 rear Being built for NA

Mechanic a

I'm also not fixated on the shortblock it's just I notched my Pistons excessively when I put it together and now I want them out. So if I'm changing those why not better than stock

96capricemgr

iTrader: (1)

I have an LS3 and would not go buying the rectangle port heads. If one looks at things with an open mind the LS3 makes LESS hp per cube than an LS6 and has a little more compression to accomplish that and that is on a 4.065 bore, the 4.0 or 4.03 bore you are likely to use doesn't help things.

Look at the thread I started https://ls1tech.com/forums/generatio...hetically.html

The LS3 got more gear than the cathederal stuff 6L40 has a 4.03 first and you are looking to use a 2.48 first and a modest rearend gear and stall.