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Discussion Starter · #1 ·
You know the 265ci "Baby" LT1?

It has the same reverse flow cooling but the rods are about 1/4" longer and the stroke about 1/2" shorter.

Now imagine that motor with the larger bore of the 350 with some nice lightweight forged pistons, plus the LT4 head and intake.

We already know the LT1 will support 12:1 compression with the good pump gas, careful cam selection and a low temp thermostat.

With proper balancing, a line bore and zero decking, this could be a real nice high revving engine like the old 302.
 
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Discussion Starter · #2 ·
Eric it begs the question, why?

If you build a good light weight rotating assembly 350 or bigger it is still going to rev as high as one could ever want.
The management and valve train , in my mind, is going to be the limiting factor ,not the bottom end.
The only place I see a small engine weighing the same as a larger one belonging is in a limited class or where someone is trying to prove a point.
I really think the old 67-69 Z-28 302 is remembered a little meaner than it was.
A buddy had a stone stock 68 Z.
M-21 3.73 gears. It would not set the world on fire.
A 70 370 horse LT1 was a much stouter piece.
Gerry
 
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Discussion Starter · #3 ·
It would be really bad if it was in a really lighter car, like an F body, but our cars are big pigs... I'm hoping to get into the 13s in time for the Shootout though.....
 
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Discussion Starter · #4 ·
I sent my old L99 crank and rods to a guy intending to build just that motor but with LT1 heads, but like mentioned above you are not going to rev it high enough with the stock engine management. Another thing is the LT4 heads are too big for most 350s so they woulf probably be borderline too big on a 302(yeah a stock bore and 3" crank, a .030" overbore makes it a 306) even spinning to 8K.
 
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Discussion Starter · #5 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by 95wagon:
Eric it begs the question, why?
Gerry
<HR></BLOCKQUOTE>

Which begs the question... why not?

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<BLOCKQUOTE>quote:</font><HR>Originally posted by Nory:
It would be really bad if it was in a really lighter car...<HR></BLOCKQUOTE>

I wasn't suggesting putting it into a B-Body. Hell, we should really be putting 502's into them. I'm just talking about the engine on it's own merits.

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<BLOCKQUOTE>quote:</font><HR>Originally posted by 96capriceMGR:
...you are not going to rev it high enough with the stock engine management. Another thing is the LT4 heads are too big...<HR></BLOCKQUOTE>

Forget engine management. There are aftermarket solutions, but I'm talking about the engine itself.
And if you built something like this, the only reason to do it is because you can rev the piss out of it, so you'd be using a pretty big cam anyway.
And the 350 isn't going to rev as willingly, nor as high. It CAN'T, because it has a longer stroke, so it's piston speed is going to be starting off higher to begin with.

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All I'm saying is that the engine I mentioned, on it's OWN merits, is an interesting combination with a lot of potential.
 
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Discussion Starter · #8 ·
I always wanted a vega. Screw LT4 heads, put some fully ported AFR heads and a cam with some huge duration cam. Get a early one with a split bumper use camaro tailights and spoiler on it. Do the interior like a Z/28, houndstooth and black viynl. Wow i need a better job lol.
 
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Discussion Starter · #9 ·
I saved this post from some message board somewhere a long time ago...

=============See Below===========
Subject: Screaming 311 LT1 destroker

George posted this about destroked LT1's:

If you wanted to make a high revving beast I would look into de- stroking the LT1. GM made a prototype f-body that was de-stroked 301 CID. They said it was the highest revving GM engine ever, 7 or 8K
redline and the best setup for winding roads. I forget where I read it. It was in two mags. I also read it is not hard to do, it is just like installing a stroker kit. You just need to match up crank, rods
and pistons. They had a 0-60 to time time... it was crazy but I forgot it. Good luck and keep me informed!

Thanks, will do.

1 year ago I started a thread about building a 311 LT1 using L99 crank 3.0' stroke, 1.5" throw and rods 5.94". Wore out two flame
retardant suits fielding the responses.

Tim Whiting sent me a note at that time:

I ran the numbers on putting a L99 4.3 crank and rods into a L05 5.7 block, and came up with a 311. IIRC, the rod to stroke ratio was somewhere in the range of 1.82:1, which is almost as good as the 302's 1.9:1. Basically it would be a 302 with 9+ more cubic inches depending on overbore. Add a set of vortec heads and a good cam and it would be a screamer, and I'm pretty sure you could make the same
thing with a LT1 block. I know a few on here are going to ask Why would anyone want to go to all that trouble when you could just buy a LT1? Well, can an LT1 rev to 9000 reliably? A 302 can, and unless the L99 crank is a weak one, this 311 could too.
Caveats:
1. The true rod/stroke would be 1.98, something close to the NASCAR
oval cars, and even better than the T/A SCCA? 302.
2. The relatively larger main journals on the LT1 would keep the revs
down to 7000 - 8000 as you mentioned. Bigger journals = more heat,
less livability at a given rpm. 9k was barely possible, even with the
small main journal 283 - 302 - 327 engines.
3. Any 350 flat-top piston with a usual compression height could be
used. GM worried about the details for us and made the way-long L99 rod. The longest production SBC known to man lets us forget about significant compression or block deck
height issues. Even quench is taken care of with the LT1 heads. KB231 pistons look pretty good @ 440 grams. Forged may be better.
4. L99 crank and rods are procurable.
 
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Discussion Starter · #10 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by rocketman442:
Screw LT4 heads, put some fully ported AFR heads ...<HR></BLOCKQUOTE>

I disagree. The LT heads, all of them, are VERY good, and you should not underestimate the benefit of the reverse flow cooling.
 
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Discussion Starter · #11 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by LT1_4DR:
Well, can an LT1 rev to 9000 reliably? A 302 can, and unless the L99 crank is a weak one, this 311 could too.
Caveats:
1. The true rod/stroke would be 1.98, something close to the NASCAR
oval cars, and even better than the T/A SCCA? 302.
2. The relatively larger main journals on the LT1 would keep the revs
down to 7000 - 8000 as you mentioned. Bigger journals = more heat,
less liveability at a given rpm. 9k was barely possible, even with the
small main journal 283 - 302 - 327 engines.
<HR></BLOCKQUOTE>

Well since Eric kind of moved the goal posts because now this engine and its application is open with basically no rules. I just wanted to through out a couple of things.

Using the correct parts a 5.7 to 6.0 litre SB Chev will be able to run in the 8000 and higher ranges.
Many of us that ran Trans Am a bit ran 2.0 rod to stroke ratios with 6.0 rods on 3.0 cranks. Funny thing many faster guys were using 3.1 inch cranks for more torque
And others were taking the weight penalty and running bigger engines but unfortunately we were limited by 16-10 wheels and the brakes that would fit. Consequently the small engine cars often would lap faster because they would brake deeper because of their lighter weight. But when the drag races on the front straights and out of the pits occurred, there was pretty much no question who had the big engines.
When we ran the car in IMSA we were still running the engines to 86-8700 even with 3 9/16 and 3 5/8 strokes. The 6.0 litre engines were still running with in a couple few hundred rpm of our 5.0
As for the big verses small journal question on production 302's, only the 607 1967 Z-28's had small cranks. The more known and plentiful 68-69 engines were large journal cranks with their more advantageous main to rod overlap and resultant crank rigidity.


So I guess it all comes down to what you want. The only really high revving SB Chev I deal with right now is an old Can Am car.
It is a fairly high-strung 305-inch Lucus-Kinsler injected Aluminium Chev.
There are two main reasons it is still a 5.0 litre.
#1 I wanted it to be as it was it its heyday.
#2 the transaxle is torque limited.
The biggest difference I see between it and other cars with larger engines it runs against is a high-strung race piece that I had to be on maintenance wise all the time while the other cars are sitting under their covers and guys had left the track for cocktails.

So Eric why stop at 302 inches? Why not destroke further?
If you are trying to build the all time high rpm engine go ahead, but if you are only talking 8-9000 rpm you could build it bigger.

Or how about this, go ahead and build your purposed engine and then we can stop all this theorizing.
I personally will stand by my statement. Unless you are rule limited I see no reason to build a small cube engine if it is going to weigh the same and especially not if cost is not an issue.

I am not saying a tiny SB Chev at 9K is not music but from my personal experience it is not necessarily the quickest way between A and B
Regards, Gerry Charlesworth
 
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Discussion Starter · #12 ·
<BLOCKQUOTE>quote:</font><HR>Originally posted by EricTheBald:
I disagree. The LT heads, all of them, are VERY good, and you should not underestimate the benefit of the reverse flow cooling.<HR></BLOCKQUOTE>

I wasn't saying they weren't good, I just thought the AFR's were better flowing in the high lift ranges
 
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