The 350 Engine Chevy Should Have Built

[beren]

This is a spawn from the 327 thread. I didn't want to hijack it anymore than I already had, sorry!

 

In reference to this article, The 350 Engine Chevy Should Have Built, I asked if the same principles applied to the LSx family of engines. I got the following replies:

 

 

Beren' date='

 

I'm sure the principles hold up in the LS engines. I don't know, however, if the quench effect is as pronounced though with the (presumably) more efficent chamber design those engines use.

 

The rod/stroke ratio also tends to be shorter in the LS engines. That means faster instantaneous piston accelleration, which typically means more low-rpm airflow. In older engines, the increased rod angle increased stress on parts, and some thought that the benefits of a long rod outweighed the air pumping factor. Perhaps with the LS engines the parts are of better quality and this isn't a concern. I don't know... but it seems to work.[/quote']

 

and

Not sure that isn't the case. But I'd still want upgrades in the rod bolts at a minimum if I was doing an LS1. Prior to 2001 the rod bolts on all LS1s are considered very weak links when adding power.

 

I found out the hard way!

 

Mike

 

My new question is' date=' are the parts used in the article still available in decent quantities today? For example, they mention using Ford Rods from their 300ci Inline 6. Are those available? I have very few sources (none is few, right?) for parts, as I'm just getting into tinkering with my Z.

 

I guess one more question: How esoteric is this build, really? Is this something that would need to be torn down every 2000 miles because of the high compression? The way the article reads, the engine sounds like someone wanted a 400HP daily driver, and found a way to do it. How off am I?

 

Sorry for all the questions, especially sorry if Grumpy has already posted links with all of the answers to my questions...

 

Edit: Double sorry, as I realized that this article has been linked at least once before

Second Edit: Yup. Grumpy posted about this already, so I'm doing my reading.

[dr_hunt]

That article is alittle dated. There is magic with the 3.25 inch stroke. Nascar has been running that combination for years, ie. sb2.2, turning 9500 rpm and beyond for 500 miles.

 

You can build the same thing, but I'd leave the ford rods in the trash and go with some good 6.2 inch units from eagle, manley, oliver, carrillo and the like. Eagle makes cranks, others do as well. It would be a good build.

 

Afr still makes great heads and they flow better now than they did back then.

[Pop N Wood]

I picked up an engine master's magazine a month or two back. They had a pretty good article with all types of engine building tips, including quotes from some of the engine builders who had won their engine building contests.

 

The one that caught my eye concerned big bore-short stroke vs. big stroke, short bore engines. This guy believed that the big bore-short stroke engines only look better until you consider detonation. Once you factor in detonation, the longer stroke motors win.

 

I'll have to look for the magazine.

[beren]

That article is alittle dated. There is magic with the 3.25 inch stroke. Nascar has been running that combination for years' date=' ie. sb2.2, turning 9500 rpm and beyond for 500 miles.

 

You can build the same thing, but I'd leave the ford rods in the trash and go with some good 6.2 inch units from eagle, manley, oliver, carrillo and the like. Eagle makes cranks, others do as well. It would be a good build.

 

Afr still makes great heads and they flow better now than they did back then.[/quote']

See? This is what I meant. I didn't even know what I didn't know. (I still don't)

 

Am I going to be better off street-wise (maybe some auto-x) just going with an LS1/2/7? (Ya, I know I'm dreamin' about the LS7 bit... /grin)

[fastzcars]

If the LSX engines were around when I stared my swap I would have used it. I think you should look for a LS2. 400 hp stock is great. And they'r just starting to show up at the recyclers and ebay.

[boodlefoof]

 

I guess one more question: How esoteric is this build' date=' really? Is this something that would need to be torn down every 2000 miles because of the high compression? The way the article reads, the engine sounds like someone wanted a 400HP daily driver, and found a way to do it. How off am I?[/quote']

 

I think this type of build is a very good, reliable and realistic street performance engine. I certainly wouldn't expect it to need to be torn down with any more frequency than a normal engine. Some might say that the cost outweighs the benefit... and that you could just build a 4'' bore 350 with 5.7'' rods. That may be true. But, the long rod and tight quench will allow running more compression with the long rod engine without as much risk of detonation.

 

In the article, they had that engine running 11:1 on 87 octane. Now, there is a point of diminishing returns with compression, but the same build could probably have run 12:1 compression, used a slightly longer duration cam, and made more power while still using pump gas. And, you could buzz the thing fairly high for fun.

 

I agree that the odd Ford rods could be replaced by some over the counter long rods. You might even be able to find an over the counter piston that would work with the combo.

 

On the bore v. stroke debate... a smaller bore can be less prone to detonation. However, a smaller bore will also reduce displacement and will often reduce flow characteristics, so there is a tradeoff.

[dr_hunt]

A common fact that has to be remembered is that there is no free lunch. If you have a motor that makes 300HP and another motor of the same type that makes 500HP, the one that makes 500HP is going to wear parts faster. And by that I mean rings, bearings, heads, valve springs, and is generally going to stress parts harder and all this necessitates more frequent freshening and/or rebuilding to maintain peak performance and reliability.

 

What you do is build 6 or 7 motors and swap them out every 15K to 20K miles and then freshen or rebuild the ones you take out. That'll keep you in the game at the peak all the time. If you can't afford that then knock on wood and stay in good graces with the MAN upstairs.

[beren]

What you do is build 6 or 7 motors and swap them out every 15K to 20K miles and then freshen or rebuild the ones you take out. That'll keep you in the game at the peak all the time. If you can't afford that then knock on wood and stay in good graces with the MAN upstairs.

 

6 or 7 motors? My wife would *kill* me! I *might*, let me emphasize that again, *might* be able to convince her that two motors were necessary, but that's only because I have two dead l28's in my garage right now, and no funds/desire to get them torn down and rebuilt. The only reason I haven't gotten rid of them is I am hesitant to take them to a junkyard, as no one makes them anymore...

 

In any case, this has been great info! Thanks for the patience whilst I come up to speed with our Great American Hobby (HotRodding). Note, the fact that I refer to HotRodding as the Great *American* Hobby is in no way meant to demean any of our brethren overseas, it was merely to point out that we had the hotrods first...