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Got with my engine builder yesterday........this is what we have going:

Head Volume CC:.... 56cc
Flat-top Pistons:...... 5cc valve reliefs
Deck Clearance:...... .004"
Gasket Thickness:... .030"
Quench:............... .034"
Cylinder Bore:........ 4.040"
Gasket Bore:.......... 4.110"
Stroke:................ 3.875"
Rod Length:............... 6"
ABDC @ 0.050 Lift....... 64*
Plus 15 Degrees

SCR 12.91:1
DCR 10.36:1

Using the calculator at the below link:

http://www.kb-silvolite.com/calc.php?action=comp

If anyone has a "better" calculator.......push it my way :) !

KW
I like this calculator:

http://www.not2fast.com/turbo/compression/compression.shtml

I got 13:1 static compression and 9.1:1 dynamic compression. It is slightly on the high side but can certainly be tuned for.

The assumption, however, is that the seat-to-seat IVC value equals tot he .050" lift IVC + 15 degrees. It may not be true with solid roller cams as they are more aggressive. So the dynamic compression would end up higher due to a smaller IVC angle.
 

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Engines are engines for the most part. The LSX doesn't use a 23 degree head so fab a set of heads for an LT at 18 degree or better and it will make just as much power NA as a LS does. The LS engies just took what racing was already doing and made it a production engine. Put an 18 degree head on Mike's car and it will run 9's.
 

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Engines are engines for the most part. The LSX doesn't use a 23 degree head so fab a set of heads for an LT at 18 degree or better and it will make just as much power NA as a LS does. The LS engies just took what racing was already doing and made it a production engine. Put an 18 degree head on Mike's car and it will run 9's.
Mike, are you up to the challenage???? Do it!!! Make history again!!!
 

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I have never found anything that really makes big power changes is cheap to do. I run 23 degree so I can run the stock LT intake but if the time comes that I really don't care if I run that intake then 18 degree or better is what I would do.

Changing a set of heads to work on our blocks is really nothing compaired to making a block. I know what a set of these heads would do on anyone's motor and it would take you to the next level. If you want to play the LS stuff then you have to have what they have.
 

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Good grief Charlie Brown. I say if you're gonna go to all the trouble of doing 18 degree heads you might as well go SB 2.2 heads/intake and be done with it. jMHO.
 

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With all due respect, I'm already at "the next level" and LS stuff doesn't scare me at all :)
I'm already at the next level :) Yes you are 1FAST94

I am in the process of trying to step up to this level NA at full weight with the ability to spray into the 9's on a mild 1st stage shot. That would require a LTX 23 degree head / solid roller cam combo making about 500-550 rwhp NA.

The original poster wants a 650-700 rwhp LTX naturally aspirated combination. I still don't see where to find that extra 100-150 rwhp with our block and a 23 degree head, and still drive it on the street. Maybe at 13 or 14 to 1 CR on E85 with a .74x lift cam spinning up to 8000 rpm. And that's if E85 is even an option depending where you live. Am I missing something here?

Jeff, with all due respect, most Guys including myself do not have the expertise or funding to pioneer a 18 degree head to our LTX motors. I would love to see the potential of that combination however.
 

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My personal opinion is that anything other than 23* heads should be reserved for either FI applications or very very light cars. These might not be the hot setup for Mike, as they would probably move the power up into a basically unusable area. Now Jeff on the other hand, would make lots more power I think. But then you get to the point of exactly how much power is too much? I believe with these heads and Jeff's setup with a production LT1 block ;) you might find out exactly how much power a production block can make before it spits the crank out the bottom or splits down the middle. Just saying.
 

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One point on the LS stuff that I have not seen anyone talk about that makes an LT engine better in its stock form. You are aware those LS engine only have ten head bolts and if you push them much with a blower or nitrous they will not hold the heads on? You will blow head gaskets on those LS engine if you want to make more than mid level power.

You HAVE to BUY a LSX block to take those engines to the same level you can take a LT or small block on our stock blocks with only adding 4 bolt caps. Even with 23 degree heads you can make more power with the old small block when you jump to power adders in total cost than an LS engine.

I'm not an LS basher as they are better motors to the mid level because of the heads on them. But to stay on topic the LT block will hold more power than it's LS counter part because the heads will not stay on. A set of 4 bolt caps with a line hone is cheaper than an LSX block.

I'm still going to push Mike to get an 18 or even better 15 degree heads with a Wilson intake. Thats worth 100 to 150 HP and thats another level.
 

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I will clarify my last comment. Change to a 4" stroke to get the air flow up, change to an LS computer or after market and rev it to 7500 to 7700. It will stay together and make some big numbers. I know one guy using a normal SB doing an 18 degree setup with those specs on a 400 stock block and it works in that RPM band. Just don't over rev it as Im pretty sure he blew it up one time due to a tranny or drivetrain failure. With a setup like that if the load is removed it will rev to the moon before the rev limiter can stop it.

But it runs with the NA big blocks from what I have seen.
 

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One point on the LS stuff that I have not seen anyone talk about that makes an LT engine better in its stock form. You are aware those LS engine only have ten head bolts and if you push them much with a blower or nitrous they will not hold the heads on? You will blow head gaskets on those LS engine if you want to make more than mid level power.

You HAVE to BUY a LSX block to take those engines to the same level you can take a LT or small block on our stock blocks with only adding 4 bolt caps..... But to stay on topic the LT block will hold more power than it's LS counter part because the heads will not stay on. A set of 4 bolt caps with a line hone is cheaper than an LSX block.
While in agreement with Jeff regarding the above wording, another factor and one Jeff has omitted, is that the LSX block is iron.
Another issue when dealing with high output durability is to swap out the aluminum block. Too unstable but not a factor with OEM
torque output.
My personal opinion is that anything other than 23º heads should be reserved for either FI applications or very very light cars.
Josh, AFAIK, you have it reversed. FI can tolerate less than optimum head flow successfully whereas NA would benefit more with
the better flowing heads and be hurt more with the inferior heads.
 

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I agree with everyone here that there is another level that would propell me into the 9's (potentially) and actually considered it over this last winter when I had the engine out of the car after two years of running on it. And I have to also agree that not being pushed, I only raised the compression slightly, went to .040 over and installed titanium intake valves, when I could have installed a larger cam, domed pistons and efi (Ls computer) ignition. I guess I want to wring every hundreth out of this OBD I stuff before moving on. I hope to see some 10.40's, maybe high 30's when the good air rolls in. Who knows, I may put some nitrous-on-a-button in there and spray 100 shot in high gear and see what happens :)
 

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Josh, AFAIK, you have it reversed. FI can tolerate less than optimum head flow successfully whereas NA would benefit more with
the better flowing heads and be hurt more with the inferior heads.
What I'm saying is that the cork in Jeff's combo, if you want to call it that, might be his heads. FI can tolerate less head flow but would make more power with less of a restriction. Boost PSI goes down but power goes up.

Now what I was saying with Mike Harris's combo is that the super-killer-18*-15*-SB 2.2 whatever degree heads, is that with only a 383, he's going to have to spin it higher than the LTx pcm will allow to really make it worth it. Now, if he were to follow Jeff's advice and go 408, and go with either a LSx or FAST type PCM, the heads, I believe, would now start coming into their own.

Now, is the expense of getting rid of your perceived 23 degree "handicap" worth it? Maybe, maybe not. Is 150 horsepower worth whatever it's going to cost to go this route? If you're Mike Harris, probably not. He's got a highly refined combo that's the baddest of the bad for conventional setups. If you're starting from scratch, this setup would probably offer more bang for the buck.

I dunno, I'm just rambling now. I've built an 18 degree motor and I will probably never do it again. Too expensive. You guys priced that 18* crap??? Yikes! From the heads, to the intake, to the shaft mounted rockers. $$$$$$$$$$cwm8s

HTH.
 
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