Lightweight Valves
Thread Starter
Drifting
Joined: Mar 2006
Posts: 1,489
Likes: 5
From: Atlanta GA
Lightweight Valves
What are the performance gains from using these?
If a motor is not spinning past 7K, is there a real difference between using SS, Hollow, or TI valves?
Also, should the lightweight valves be used on the Intake, Exhaust or both?
If a motor is not spinning past 7K, is there a real difference between using SS, Hollow, or TI valves?
Also, should the lightweight valves be used on the Intake, Exhaust or both?
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Intake is where you will run into problems first due to its larger size. Trade-off is stiffer springs to control heavier parts vs. lower stiffness springs to control lighter parts.
Thread Starter
Drifting
Joined: Mar 2006
Posts: 1,489
Likes: 5
From: Atlanta GA
thx, performance wise, what do you stand to gain?
In theory i would think an engine could rev quicker and higher with lighter valves, but at the same time i would tend to think that rev capabilities are bottlenecked/governed by the weight/friction of the rotating assembly and not necessarily the opening/closing of the valves...
so it seems as though lighter valves are more for reliability/longevity than performance...
am i missing something??
In theory i would think an engine could rev quicker and higher with lighter valves, but at the same time i would tend to think that rev capabilities are bottlenecked/governed by the weight/friction of the rotating assembly and not necessarily the opening/closing of the valves...
so it seems as though lighter valves are more for reliability/longevity than performance...
am i missing something??
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Because the intake valves are usually physically larger than the exhaust valves, they are often composed of a different material or other "technology" to try and keep their weight about the same as that of the exhaust valves. You generally want the spring "tension" for all valves to be about the same, especiallly in an engine like a V8 with a single camshaft (like our LSx engines).
The material (technology) used for the valves is determined mainly by the environment they live in ... an intake valve is cooled by the incoming air/fuel mix every time it opens ..... an exhaust valve is heated by the outgoing exhaust gases every time it opens ...... so you will see differences in valve design in one engine just based on that.
Thread Starter
Drifting
Joined: Mar 2006
Posts: 1,489
Likes: 5
From: Atlanta GA
Also, wouldn't your pistons, rods, & crank be allot more weight to throw around than valves?
Ultimately what I am seeking to understand is what going from hollow stem valves (which are already light), to TI valves would benefit me (or anyone for that matter) from a performance (rwhp/laptime) perspective? and if it would be worth the extra $$ in doing so.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
thx, performance wise, what do you stand to gain?
In theory i would think an engine could rev quicker and higher with lighter valves, but at the same time i would tend to think that rev capabilities are bottlenecked/governed by the weight/friction of the rotating assembly and not necessarily the opening/closing of the valves...
so it seems as though lighter valves are more for reliability/longevity than performance...
am i missing something??
In theory i would think an engine could rev quicker and higher with lighter valves, but at the same time i would tend to think that rev capabilities are bottlenecked/governed by the weight/friction of the rotating assembly and not necessarily the opening/closing of the valves...
so it seems as though lighter valves are more for reliability/longevity than performance...
am i missing something??
In general it is the valve/cam system that is the limiting factor .....
Think of it this way ... in a half revolution of the piston and crankshaft the camshaft and a valve will have to have performed an open/close cycle in a much shorter period of time. If you are an engine designer this is one of the issues you have to look at .... for 180 degrees of rotation in the crankshaft when do you start/end valve opening and closing, and how "high" do the valves have to rise during this period ... and overall what is the limiting factor (redline) for this engine ... the valvetrain or the crankshaft/piston assembly ???
Thread Starter
Drifting
Joined: Mar 2006
Posts: 1,489
Likes: 5
From: Atlanta GA
Yes, all else being equal, an engine revs higher with lighter valves. And yes, the weight/friction/inertia of the rotating assembly is a part of the equation .... BUT .....
In general it is the valve/cam system that is the limiting factor .....
Think of it this way ... in a half revolution of the piston and crankshaft the camshaft and a valve will have to have performed an open/close cycle in a much shorter period of time. If you are an engine designer this is one of the issues you have to look at .... for 180 degrees of rotation in the crankshaft when do you start/end valve opening and closing, and how "high" do the valves have to rise during this period ... and overall what is the limiting factor (redline) for this engine ... the valvetrain or the crankshaft/piston assembly ???
In general it is the valve/cam system that is the limiting factor .....
Think of it this way ... in a half revolution of the piston and crankshaft the camshaft and a valve will have to have performed an open/close cycle in a much shorter period of time. If you are an engine designer this is one of the issues you have to look at .... for 180 degrees of rotation in the crankshaft when do you start/end valve opening and closing, and how "high" do the valves have to rise during this period ... and overall what is the limiting factor (redline) for this engine ... the valvetrain or the crankshaft/piston assembly ???
so hypothetically speaking, if i dont plan on exceeding the ability (redline) of a 100 gram valve, than i do not benefit from going to a 50 gram valve...?? (other than less stress on parts)
ALL else held equal, does lighter valves/softer springs = more rwhp at a given redline, say 6500?
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Are you referring to the top speed in each gear? or total top speed of the car? <---- Top speed in gear .... which theoretically affects "top speed" ..... though for many cars aerodynamics becomes the limiting factor ... not engine speed.
Also, wouldn't your pistons, rods, & crank be allot more weight to throw around than valves? <---- Yeah, but pistons have these really big things called CONNECTING RODS which tend to be easier to control than a valve spring .... but ultimately yes ... thet are a PART of the equation.
Ultimately what I am seeking to understand is what going from hollow stem valves (which are already light), to TI valves would benefit me (or anyone for that matter) from a performance (rwhp/laptime) perspective? and if it would be worth the extra $$ in doing so. <--- see below
Also, wouldn't your pistons, rods, & crank be allot more weight to throw around than valves? <---- Yeah, but pistons have these really big things called CONNECTING RODS which tend to be easier to control than a valve spring .... but ultimately yes ... thet are a PART of the equation.
Ultimately what I am seeking to understand is what going from hollow stem valves (which are already light), to TI valves would benefit me (or anyone for that matter) from a performance (rwhp/laptime) perspective? and if it would be worth the extra $$ in doing so. <--- see below
Switching to a lighter valve, while changing nothing else, is not going to make a wit of difference to your engines performance.
Switching to a lighter valve, while changing nothing else, would only allow you to rev to a higher engine speed (redline) if the maker of the valves can demonstrate that the engines current redline id limited by the valves/springs rather than the rotating mass of the pistons/crankshaft (or you are willing to grenade your engine to determine what parts fail first).
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
makes sense...
so hypothetically speaking, if i dont plan on exceeding the ability (redline) of a 100 gram valve, than i do not benefit from going to a 50 gram valve...?? (other than less stress on parts)
ALL else held equal, does lighter valves/softer springs = more rwhp at a given redline, say 6500?
so hypothetically speaking, if i dont plan on exceeding the ability (redline) of a 100 gram valve, than i do not benefit from going to a 50 gram valve...?? (other than less stress on parts)
ALL else held equal, does lighter valves/softer springs = more rwhp at a given redline, say 6500?
Lighter valves do not not give you more HP. However, if a lighter valve allows an increase in the engine redline it MIGHT allow for higher horsepower ..... but in a "stock" LSx engine, since the current redline (6,000 for an LS1, 6,500 for an LS6) is already past the engines peak HP output ..... revving higher has little benefit.
Burning Brakes
Joined: Feb 2001
Posts: 793
Likes: 2
From: Milwaukee & Long Beach WI & CA
Would lighter valves extend valve spring life if everything else (redline, cam profile, etc) stays the same? Or does it not matter as long as your springs are stiff enough to control the valve for a given cam?
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Standard valves are good to 6500, above that the light wt sodium filled valves are needed. light wt valves and better springs are a must for 7000 rpms
yes no
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
When the Z06 got the lighter valves and gained 20 HP, GM Powertrain attributed the 20 HP to things like the different cam profile, elimination of the pup cats, de-screened MAF ...... I've never seen anything that said that any of that 20 HP came because of the springs/valves.
GM Powertrain said the only reason that they went to the new valve/spring combination was because the cam had a higher lift and a "faster" opening speed for the valves, requiring lighter valves ... which allowed for "weaker" springs.
Racer
Joined: Sep 2006
Posts: 260
Likes: 1
From: Chesterfield MI
Tighter springs control the valves. When springs are opening, springs are closing, so it's a wash. The tension on both sides make it virtually the same tension wise. There have been exhaustive studies on this. The big thing is to make sure you have enough spring to control your valves with your cam profile. Float = bad!
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
One of the challenges with normal valves and springs above 6500 is valve float.
Your engine may spin to 7000 rpms but there is little if any additional power past 6500. Which is still not a bad thing, as shifting at 1500 rpms above peak HP is desirable, so that when you do shift, the the rpms drop into that sweet spot.
One of the items too look for is an intimidate drop, or hick-up on the hp line on a dyno chart. this may be an indication of valve float.
Your engine may spin to 7000 rpms but there is little if any additional power past 6500. Which is still not a bad thing, as shifting at 1500 rpms above peak HP is desirable, so that when you do shift, the the rpms drop into that sweet spot.
One of the items too look for is an intimidate drop, or hick-up on the hp line on a dyno chart. this may be an indication of valve float.
