L82 HP Boost

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Apr 23, 2014 | 11:59 AM

#21

jb78L-82

Le Mans Master

Joined: Oct 2007

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From: RI, Now Franklin/Nashville TN

Quote:

Originally Posted by bluedawg

Why would you figure that it would take 11 to 1 compression to 400 gross hp? I don't see it that way, 400 should be obtainable at 9/9.5 to 1 afr shows several combos making that. Given the fact that aluminum heads disapate heat he could go 10 to 1 with the right cam shaft and not have any issues.

For three reasons:

1. I was referring to new Aluminum heads and using the L-82 cam, 400 hp was probably not realistic.

2. I am hoping for 400+ with the AFR heads and 10-10.2:1 compression with the Retro Roller Howards cam-.525/.525, LSA 110, 219/225 duration and I am going to be iffy hitting over 400+ gross HP. Trying to hit 400 with 9-9.5:1 is really iffy. My builder for the bottom end confirmed my estimates so if I can barely make it to 400+, definitely not happening with 9:0-1, AFR's or not, MAYBE with 9.5:1, pretty good to go 10:1. I hope that I am wrong, and you are right.

3. 370 HP LT-1's had a solid lifter camshafts with 11:1 compression in 1970-granted old technology and heads etc-but could only muster-370 Gross HP.

Hope that explains.

Last edited by jb78L-82; Apr 23, 2014 at 12:08 PM.

Apr 23, 2014 | 07:32 PM

#22

7t9l82

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Joined: Oct 2010

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From: melbourne florida

2023 C3 of the Year Finalist - Modified

it doesn't , there were and are 350/350 cammed engines running 400 h.p. headers , good intakes , properly set up carburetors. and most importantly much improved cylinder head flow. with 9-1 compression it is an uphill battle but going to 10-1 changes a lot . we had more than a few 350 engines making that power 30 years with ported turbo heads and double hump heads.so with newer heads it is pretty easy. it can be done.

Apr 23, 2014 | 08:20 PM

#23

bluedawg

Safety Car

Joined: Jan 2009

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From: anchorage ak

Quote:

Originally Posted by jb78L-82

If I recall correctly the 355" that afr has a dyno page on is 9 to 1 and makes 420 gross with about the same cam. I think you easily hit 400 horse, think that you'd hit 400 horse with the same set up at 9 to 1. I've never seen back to back dyno sessions with 1.25 less or more compression, but from all I've ever heard or read 1 point of compression with all else being the same (cam, heads intake etc.) Is worth 3% increase or loss in power, if the compression is to low for the cam, it will be doggy down low, if the compression is to high for the camshaft you'll either have detonation issues or you'll have to dial back timing looseing power. Figuring your dynamic compression can help determine if your camshaft is in the ball park for your compression. Adding compression allows you to run more duration with a latter intake valve closing point, but then you get into needing larger intake runners and such. What did your dcr figure out to? As far as the 1970 lt1 head's didnt flow as well, the fuel had a higher octane rating and the cam was old school grind by today's standards. you should look at afrs web site. There's plenty of 9 to 1 355" combos out there making 400 horse with ok heads.

Last edited by bluedawg; Apr 24, 2014 at 01:18 AM.

Apr 24, 2014 | 04:01 AM

#24

bebezote

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