valve question

**shady milkman** · 09-23-2006, 04:02 PM

why didn't the ls1's have a 4 valve design...aren't 4 better then 2? 2 intake, 2 exhaust?

**SSmoky01** · 09-23-2006, 04:37 PM

Originally Posted by shady milkman

why didn't the ls1's have a 4 valve design...aren't 4 better then three? 2 intake, 2 exhaust?

Where did you get 3????????????? A four valve design is more costly. A ZR-1 Corvette had the 4 valve set-up. A LT-5 crate motor (when you could buy em) for those cars were like 20 grand.

**shady milkman** · 09-23-2006, 04:46 PM

how many valves do the ls1's have?

**Mr. Luos** · 09-23-2006, 04:53 PM

2 per cylinder.

**shady milkman** · 09-23-2006, 05:49 PM

man i'm retarted..but that still seems so low..wouldn't 4 valves really jump up performance..(yes i know expensive)

**UHKILEZ** · 09-26-2006, 11:32 PM

Number of valves within a given head design has advantages to each design.

1. 2-Valves per cylinder head (1-intake and 1-exhaust) will have better low rpm torque, but less HP at higher rpm's, all else being equal.

2. 4-Valve per cylinder head (2-intake and 2-exhaust) will have better high rpm HP, but less torque at lower rpm, all else being equal.

Also, small displacement I4 or V6 need 4-valve heads for better "breathing" at higher rpm as they need higher rpm to build power, we don't. Simply changing the cam, in an LSx engine along required parts thereof, intake manifold, better flowing heads etc. will increase HP or "performance" as you indicated, as the new cam and required parts thereof will allow higher rpm operating range, thus increase HP as well as increase torque by expanding the range of torque higher in the rpm.

Example;

LS1-maximum torque is @ 4000rpm and maximum HP is @ 5200rpm

LS6-maximum torque is @ 4800rpm and maximum HP is @ 6000rpm

Thats why GM developed the LS6 engine, as they changed to better flowing heads i.e. better "breathing", revised intake manifold design, more aggressive cam design and required corresponding parts thereof, as well as a pressure relief in the block design in order to allow higher rpm operating range than the LS1 engine, hence more HP and torque.

**Killer_bluebird** · 09-27-2006, 11:30 AM

There is one company that makes 4 valve heads for GM sbc blocks but they never made a version for an LS1/LS6 or LS2 small block. Here is the Link. They are very expensive, they start at about $8,000 to $15,000. The stage 2 flows Intake 348 CFM & Exhaust 280CFM, which is not that much more you can get out of a ported set of AFR, but the "High Port" version flows Intake 440 CFM!
& Exhaust 335CFM!