Funny, but GM went the opposite way with their 8 liter stuff. They built some V10s for testing, but ended up with the Vortec 8100. The 8100 has a 4.25 bore and the 8.2 Viper has a 4.03 bore That's about 11% more piston surface area on the 8100.

Note that the Viper V10 was only available because the basic engine was going into trucks. Same with the LS1/6/etc series. It was the millions of truck engines that will be sold that paid for the development and tooling for the Vette, and F-body LS's.

 

That was a few years later wasnt it? Time and technology change a lot of things. My uncle has the 8.1 in a 3/4 ton for towing a 5th wheel and all I can say is DAMN. I didn't ride in it but I did follow him towing and I was impressed at how it handled hills.

 

Which of course was in part because they could leverage the several decades of experience with the Mark IV.

My point being, with all due respect to everyone who posted; none of these decisions are based on single factors.

 

It's funny, I've had several friend's/aquaintances/family members over the years that have bought trucks to tow with; from one of the big three.

I always tell them that unless they plan on having at least 2/3 - 3/4 of their driving be steady state highway work for long distances to stay away from the diesels and go with the big gas engine option.

The ones that went diesel anyway did so because they couldn't believe that a gas engine could do the job.

501 cubic inches of splayed valve chevy not do the job?
It is to laugh...

 

I was following him with the LT1 95 Roady wagon and I was suprized at how much throttle I was using to follow him. He knows I am a gearhead so I am sure he was showing off a little but thios was in upstate NY, Watkins Glen area those familiar will attest to the grading there.

 

Going up the hill to the track? Anything coming out of the Glen going north or to the track is dam steep... the SS seems to still pull fine up that puppy at 110+ ;-)

Bret

 

We stayed at the KOA campground which is on top of the hill we came in a back way with the trailer still steep but it was more broken up than coming straight up out of town. Right out of town up to the campground(near the track) was fun in the wagon, those pesky German cars and such kept TRYING to pass guess they saw a Buick and didn't realize it was LT1 equipped. ANYONE who goes to the track should make time to hike the Gorge, much nicer than Niagra.

 

Dwayne,

Yeah I know the road you went up well... thats the way we go to the track.

I know the area well, we live 40 mins from the track and it was basically the half way point of a drive I took to get to college and back. Probably did that drive 100 times.

If anyone is going to the Glen for something give the old man and I a PM we will stop by or go grab a beer.

Bret

 

I have an aunt over in Vestal Center I try to go visit at least every other year and like to get to The Glen while in the area, that hike will wear you out but is so worth it.

 

I gotta disagree. They could've gone with the big bore BBC block and had even more cubic inches. Just imagine a factory 548cid (9.0L) BBC

The LS1 has a small bore/long stroke combo, but it looks like GM has learned how to get around that with the newer motors. THe LS2 has a 4.00" bore again and the 6.2L has a 4.065" bore.

 

I guess it depends on what you (they) were trying to accomplish at the time. If the 8.1 (496) gets the job done in 2500 trucks, an extra liter probably won't use less fuel on the highway. Obviously there were more inches available with the same stroke (see the 572). I wouldn't be surprised to see the 8100 become an 8700(530) or a 9000 (549) if the need arises. As you said, it worked for the LSX series. Rarely do they resdesign an engine and not allow for growth.

 

The big bore piston would also move away from the cylinder head at a much slower rate is what you were forgetting.

Big bore engines simply allow bigger intake ports and thus more potential for power. When run with the same ports and valves they often will not make good power due to combustion ineffeciency and low compression or nasty chamber problems.

It's no accident that you don't see huge V4s with 5 inch bores and 1 inch strokes in production or in F1. No one here has been the first to think of this! Big bore engines are less efficient and also have worse emmissions because of these problems. It's a balance not a one sided argument.

If bore was all good a massive bore 1 inch stroke V engine could give great packaging and incredible power. Then some one would come along behind you and put a 3 inch stroker crank in that engine and destroy you and increase reliability ten fold.

 

I do realize that the piston moves slower. and I don't think that big bore engines are "all that". I was just trying to learn a little more in depth about the relationship that they share. I was just looking at it from the amount of force applied to the piston and what it translates to the crank through the leverage @ 90deg angle of the stroke. I saw a pattern form during my calculations that as the bore stroke ratio moved away from square that the amount of tq applied to the crank drops some. I now think that it was an error in my calculations though due to me rounding #'s, but havn't taken the time to redo the calculations to double check.

 

No **** Erik showed up in a thread about bore and stroke... must be a freaking becon or something when this happens.

 

People actually send me to these threads Bret. I don't know why though?

I love bore AND stroke though. I try and maximize both if possible. Bore allows better heads and stroke then utilizes those heads.

If I take too much stroke out I then valvetrain limit my engine and/or kill my reliability big time. Taking stroke out a regular engine is plain stupid in general when looking at things from a performance perspective.