Camshaft Basics

[MikeMoach]

Don't most L99 do the LS3 conversion to avoid all that anyway? Meaning the VVT

[litle88]

Originally Posted by MikeMoach

Ok but I feel lost, doesn't the size of the lifters depend on the size of the cam?

No the lifters stay the same!

[CAP'N B]

Originally Posted by MikeMoach

Don't most L99 do the LS3 conversion to avoid all that anyway? Meaning the VVT

Some do and have done in the past, but the technology has advance so that you can almost get the best of both worlds, Meaning good drivability and high horsepower with aftermarket cams. L99 engines change cam degrees up to 50 degrees, but with a bigger cam a limiter is used. L99 engines have a little lower compression because they have valve reliefs in the pistons.

[litle88]

Originally Posted by CAP'N B

No, the lifter size is determined by the hole in the block that they fit in.
The pushrod length changes sometimes, depending on the cup where the bottom of the pushrod sits in the lifter is. I think a LS7 lifter is taller.

The rocker arm ratio can change the dynamic of the valve events. A 1.8:1 rocker ratio will increase lift and duration.

The engine seems to want to stall at times because the valves are open at the same time, bleeding off compression, or cylinder pressure. At higher RPM this happens too fast to make a big difference. So the engine runs smooth.

Some cams have a few degrees of advance built into them this lowers where the Power will be made in RPM's.this is called the power band.

Now lets confuse them some more. On the automatic cars with the L99 engine we have what is called Variable Valve Timing cams, this automatically advances and retards the cam. It will have both , low end power and upper end power.

All lifter bores are the same. The pushrod lengths are determined with usually .050 lifter preload on the lifters plus the distance of the lifter cup to the rocker cup.

Yes a 1.8 will add lift BUT you will be having to use ALOT spring pressure to help control the valves! Especially with an aftermarket cam and better lobes. 1.8 rockers are a bad idea on a 1.7 ratio cam.

Not all cams have OVERLAP (when both valves are open at the same time! So I'm not sure what your trying to say. Cars might want to stall be ause they are untuned or poorly tuned.

I think you need to do some more reading because a cam is advanced it doesn't mean the "power band" will be lower.

So please stop spreading Internet misinformation.

[litle88]

Originally Posted by MikeMoach

Don't most L99 do the LS3 conversion to avoid all that anyway? Meaning the VVT

They do that mainly because there are no tuners that cam properly tune a VVT cam OR they just prefer a traditional 3 bolt cam and traditional tune.

Rhino79 has proven to be very good at tuning L99's and has had a few new cam grinds from mild to gawd damn!

A good way to keep drivability is to have a matched torque converter to the cam you select.

[MikeMoach]

Originally Posted by litle88

No the lifters stay the same!

Then what does change?

Originally Posted by litle88

They do that mainly because there are no tuners that cam properly tune a VVT cam OR they just prefer a traditional 3 bolt cam and traditional tune.

Rhino79 has proven to be very good at tuning L99's and has had a few new cam grinds from mild to gawd damn!

A good way to keep drivability is to have a matched torque converter to the cam you select.

So if I get a cam with a big overlap that loses drivability right? And you're saying that a torque converter will give it drivability?

[litle88]

What changes are the base diameter of the cam if its that big, is what changes needing a longer pushrod. But most cams will usually require 7.4's chromoly of course. That's when proper pushrod length checkers come in. You gotta measure for peace of mind.

[litle88]

Yes the bigger the cam the bigger the stall speed some will require a certain stall speed some might like a loose converter others like is tight. You just gotta ask the vender from where the cam is coming from which converter would be optimal. Gears will also help tame that beast as well. It's called supporting mods bud. It's all gotta compliment each other.

[CAP'N B]

Originally Posted by litle88

All lifter bores are the same. The pushrod lengths are determined with usually .050 lifter preload on the lifters plus the distance of the lifter cup to the rocker cup.

Yes a 1.8 will add lift BUT you will be having to use ALOT spring pressure to help control the valves! Especially with an aftermarket cam and better lobes. 1.8 rockers are a bad idea on a 1.7 ratio cam.

Not all cams have OVERLAP (when both valves are open at the same time! So I'm not sure what your trying to say. Cars might want to stall be ause they are untuned or poorly tuned.

I think you need to do some more reading because a cam is advanced it doesn't mean the "power band" will be lower.

So please stop spreading Internet misinformation.

I never said all Cams have overlap, but a cam with a lot of duration and a narrow LSA will have a lot of overlap causing the LOPEY sound most Hot Rodders Like. Which I assumed the guy was talking about when he said the engine sounded like it was stalling.

Not all engines have the same lifter bores. ALL Gen3&4 LS engines do, but a Smallblock 2nd gen engine is a different lifter bore.

Read more: http://www.popularhotrodding.com/tec...#ixzz2LgrKsAqK

Advancing the valve events boosts low-end torque at the expense of high-rpm horsepower, while retarding the cam has the opposite effect.

Since arranging the valve events to boost high-rpm horsepower hurts low-rpm torque, and vice versa, the installed centerline of a camshaft is ultimately a compromise, however, the beauty of VVT systems is that they eliminate this compromise entirely by advancing the cam phasing at low rpm, and slowly retarding it as rpm increases. This allows maximizing low-end torque without compromising top end power, and maximizing top end power without compromising low-end torque. Furthermore, VVT also broadens the torque curve before the peak, and prevents horsepower from dropping off rapidly after the horsepower peak. “With variable valve timing, we typically see a 5-10 percent improvement in output at the ends of the torque and power curves,” Godbold says. “This means that torque output will improve dramatically 1,000-2,000 rpm below the torque peak, and the engine will continue making usable power up to 1,000 rpm above its power peak instead of falling off a table. Clearly, VVT flattens the torque curve substantially. (Billy Godbold is Comp Cams Guy.)

As one of the few companies that offer VVT-equipped crate motors, Mast Motorsports has conducted extensive dyno testing of GM’s VVT system on its 416ci L99 motors, which are rated at 595 hp. Retarding the cam for max top end grunt typically yields roughly 610 hp and 555 lb-ft of torque. Advancing the cam for max low-end performance nets 592 hp and 565 lb-ft of torque. It’s the classic case of compromise, but engaging the VVT results in a pull that retains both the peak horsepower (610) and peak torque of 565 lb-ft from the two prior pulls.

When tuned for maximum torque, Mast Motorsports’ 416ci L99 prefers 5 degrees of advance, while it produces maximum horsepower with 4 degrees of retard. To fully take advantage of the VVT system, however, Mast advances the cam an additional 2-3 degrees at idle and retards the cam an extra 4-5 degrees at 7,000 rpm. This not only bulks up low-end torque below the engine’s torque peak, but it also dramatically reduces the rate at which horsepower drops off after the engine’s 6,400-rpm power peak. Compared to when the cam is advanced for max torque, retarding the cam for max power produces 18 extra peak horsepower at 6,400 rpm. By continually delaying the intake closing after peak power, at 6,900 rpm the difference is a staggering 40 hp.

[litle88]

Umm we are talking about Ls blocks here Gen 3/4 here. So now your going to cut and paste? Lol oh boy

[MikeMoach]

Originally Posted by litle88

Yes the bigger the cam the bigger the stall speed some will require a certain stall speed some might like a loose converter others like is tight. You just gotta ask the vender from where the cam is coming from which converter would be optimal. Gears will also help tame that beast as well. It's called supporting mods bud. It's all gotta compliment each other.

This is what I'm trying to understand first what to do to support the cam, gears I understand but I don't get much else I'm sorry if I'm thread hacking and making this beyond the basics

[litle88]

Originally Posted by MikeMoach

This is what I'm trying to understand first what to do to support the cam, gears I understand but I don't get much else I'm sorry if I'm thread hacking and making this beyond the basics

Ok well you got the tq converter and gears, as far a drivetrain is concerned you'll also need a bigger Trans cooler. Stalls create heat.

To support the cam you'll need IMHO a katech C5r chain, matching valve springs to the cam (I am a fan of the BTR aka Brian Tooley platinum springs which have a "0" failure rate) you'll need to delete that weak chain tensioner for the Ls3 and put the Ls2 dampner. You'll also need a trunion upgrade by comp, up to you on the pump. L99's have proven to be good bit mellings 10296 is an upgrade to to the materials and blue printing already on it, and higher oil pressures. You'll also need a good set of headers. Depending on the mileage get new GM lifters or BTR SLR lifters. Then there the morel/lunaty link bar lifters.

Hope that helps.

[CAP'N B]

Originally Posted by litle88

Umm we are talking about Ls blocks here Gen 3/4 here. So now your going to cut and paste? Lol oh boy

I'm using that reference to make a point, and yes when someone tries to cut me down and make me sound stupid, I will prove them wrong by cutting and pasting and providing a link.

[litle88]

Well you posted some wrong info, with you stating Ls7 lifters are taller tells me that you are a novice, so please I suggest you keep reading and or ask questions. If you feel that you can't take being corrected then I don't know what to say, I am not here to make enemies either (per your pm) but I don't suger coat anything and I just say it like it is sir.