Cam Lsa

[FIREHAWK774]

New To Ls Series Engines, Plan On Building 427 Cu Lsx With Dart Heads With Carb With 10-1 Comp. Ratio, Just Woundering What Lobe Seperation Angle Ls Series Engines Prefer. Thinking Of 108 Lsa For Best Of Both Worlds, Great Bottom End And Hard Pull Thru High Gear. Duration @ .050 Somewhere Around 242-250.

[Mr. Luos]

What are the goals with the car??
Street? Drag?
108 is a tight LSA, but would scream.

Also, 10:1 seems fairly low. I run 11:1 on pump gas no problem.

[FIREHAWK774]

70% Drag, 11:1 Would Be Great, Wasn't Sure If You Could Run That With Pump Gas On A 108 Lsa,maybe A 110-112 Because The Loss Of Cylinder Pressure With Valves Overlapping Longer.

[LT1 > LS1]

I would raise compression if you are gonna run that much duration with the cam.


you dont want your dynamic compression level being too low. essentially, with lower compresion, it might push out a lot of fresh air/fuel before the valve closes, and not have a ton left over for the combustion cycle.

[Mr. Luos]

I would raise compression if you are gonna run that much duration with the cam.


you dont want your dynamic compression level being too low. essentially, with lower compresion, it might push out a lot of fresh air/fuel before the valve closes, and not have a ton left over for the combustion cycle.

Pretty much what I was thinking.

The 108 is a lot of overlap, thus lowering the dynamic CR. Which is the true determination of how much timing you can run with what fuel.

Of course, I run a pretty loose LSA with my stroker. 248/254 629/622 113
Got her set to 30 degrees of timing at WOT. 91 octane.

See if you can find a DCR calc.
Maybe this one will help...designed for Harley's, but DCR doesn't care about the motor.
http://www.rbracing-rsr.com/comprAdvHD.htm
Or...
http://www.ls1tech.com/forums/showthread.php?t=630637

[FIREHAWK774]

You've Got A Point, Just Thought Id Use A Little More Duration For More Cubic Inches.

[FIREHAWK774]

Great Cal. Thanks, This Will Really Help Me Get Started On My Cam Specs.

[Mr. Luos]

If it will be used for mostly drag...you can really bump that cam up. It really all depends on what you want to do with the car. Gears, tranny, etc...

I run a 248/254 at .050 hydraulic roller cam in my 402.

[FIREHAWK774]

My Plan Is To Run A Turbo 400 With 4.10 To 4.56 Out Back And Maybe A Little Nos.looking At A 9" Or 10" Converter Around 3000-3500 Stahl. But Cam Will Define Converter Used Along With Weight Of Car.

[Mr. Luos]

Yes it will.

Sounds like it will be a beast!!
Keep us updated.

This going in the Firehawk?
There are cheaper ways to get to 427 cubes...unless you get a killer deal on the LS7.

[FIREHAWK774]

Yep, Firehawk Will Be Getting A New Soul, Built The Way It Should've Left The Plant. You Say Cheaper Ways To Get 427 Ci,how?

[Mr. Luos]

The LS7 is so damn expensive. And from what I understand GM won't be selling them much longer.

If you are going to be throwing nitrous at it....why not go 408?? 19 less cubes, but thousands less.