N20LS1

Does anybody know what is the highest lift cam you could buy for a stock motor LT1, without having to change anything??????

GreatWhiteZ28

iTrader: (15)

By "anything" do you mean Valvetrain??? if so then from my understanding the stock cam is the largest for the springs and such the next size cam would be the LT4 Hot Cam and that's a fairly small cam.

daniel6718

iTrader: (36)

without having to change pistons? prolly near or above .650 lift...

96capricemgr

iTrader: (1)

Valve timing is a HUGE part of piston to valve clearance. I have heard of clearance issues with little over .600 lift on milled heads.
You are going about picking the cam all wrong though.
Even on my setup with nice ported heads and all I run well under .600 lift.

As covered springs are going to be manditory, hell at 10 years old the engine could benifit from new springs on the stock cam.

drumbo87

iTrader: (4)

you wont be needing anywhere near even a .600 lift on a stock lt1........ my le3 383 doesn't even touch the .600 lift marker. If you want to make power get quality parts that will all work together. A huge cam isn't going to help you if you can't accomplish adequate airflow to feed it. If you want quick power get a bottle, if your building a motor...... build it smart.

BsGreenZ

why not change your valve train when you do it.. buy the LT4 hot cam kit, cheap power that you can really feel...

the_merv

iTrader: (88)

Stock Valve Springs I wouldn't put past .475 lift.. they are tiny. The LT4's are at .525 max, and the Hotcam Kit puts them right there.
How many people are over .600 lift with a LT1, will the Heads even flow enough to feed that? I am just wondering, the only Head stuff I have been really researching lately was for mine so I could get a proper Cam for them.
Very big difference between LTX and LSX Heads..

fergymoto

iTrader: (129)

My new cam is just over .600 lift, and my heads peak around that area. Can't wait to run it!

speed_demon24

iTrader: (6)

You can run as much lift as you can put in it, duration and vavle events are what determines when the valve comes into contact with the piston. And when heads keep gaining flow well past 600 lift it makes no sense to not to run a cam with high lift. Big lift #'s does not mean its a big cam.

the_merv

iTrader: (88)

^^Very true..

GreatWhiteZ28

iTrader: (15)

In running a lil ol 230/236 .576/.571 in mine, stock heads........for now

Fastbird93

iTrader: (10)

About the biggest combination I've seen on a stock longblock car is the GM847 with .595 lift (1.6 rocker) on the exhaust side. I remember seeing some numbers from a long time ago saying something to the effect that .600-.605 is where you better start thinking of PTV issues.

Phoenix'97

I am a good 11-years late for this discussion and forgive me fellow members for commenting on this old thread, but I do have a contributing comment to make here. Hypothetically, using stock LT1 aluminum heads with necessary valvetrain modification for a very high lift cam and using 1.7 rockers with the geometry altered for easier operation, could you still safely use a camshaft likened to the LS7 cam? To throw out numbers here, intake lift: 0.589 in. exhaust lift: 0.593 in., duration: 200/207, lobe separation angle: 117 or 118.

I understand this discussion is based on unmodified stock LT1 heads, yet, for highest lift ground into a cam you need to modify the valvetrain! So, if you modify the valvetrain accordingly, could you use a custom LT1 grind likened to the LS7 cam? It doesn't hurt to explore this idea!

PARMY

Why try to re-write the book on LT1 mods when there are soooo many proven cams, cam/head combos etc? Seems like a waste of time to try new stuff at this point...just use what has been proven to work reliably.

Phoenix'97

From what I am seeing, not everything have been tried. Everything related to getting a second-gen LT1 car to get up and go and improve it's track time are the "proven cams" you speak of. I see nothing remotely close to an improved stock cam with wide lobe separation yet higher than factory lift. Furthermore my dilemma for the engine build is complicated by using a long runner intake manifold instead of the small runner LT1 intake but this is too off-topic for this old thread.

I understand where the original poster's mindset is at and I understand the theory behind giving a stock cam as much lift as can be ground into it without really changing anything else. Can it work safely if the heads have the correct valvetrain modifications, in my case the valve covers for the 1.7 rockers, the right springs, and the geometry reworked with unported heads? I will pose this camshaft question to the cam maker since I am dead set on smooth idle and ample vacuum levels. I am only interested in changing how much air the camshaft can supply my engine at lower to mid-range RPM and whether or not I am going to need porting if it deemed necessary for my build, which in all likelihood it may be, but I can't have port velocity take a hit, however, from the porting.

BALLSS

Phoenix

You have asked several ?'s in various threads about very unconventional mods because you feel "everything" has not been explored with the Gen 2 LT1 SBC. Nothing wrong with asking or even trying something new......but in the case of your ? in this thread what you ask is not going to provide any more, and likely far less, power, drivability, mileage, low end TQ, etc.than the several cam profiles or valvetrain components proven for the LT1.

Guys like Lloyd Elliott has forgotten more about cam grinds for various uses than most of us will ever know so aside from off the shelf cams that spec what their operating ranges is (RPM) custom grinds from guys like Lloyd provide more bang for the buck.

To improve your stock cam power and or TQ you do what people have been doing with SBC for decades like higher ratio RR, better valve springs, thicker RR studs & PR to reduce flex of those parts, free flow exhaust/headers are what will give you more TQ & HP on a otherwise stock motor and have a + benefit towards gas mileage.

If you explore some new concept you think of that does more than any of the well proven methods....please enlighten us all.

Shownomercy

iTrader: (1)

People don't run LS7 esque cam lifts on LTX junk cause, LTX junk flows like **** at factory lift levels, hanging the valve open even more won't get you anything.

Phoenix'97

I ask very unconventional questions because my approach to this planned engine build is totally different from performance/race mods that have traditionally been done and are proven on the track as such! I am also going about this with a totally different intake manifold which is a far cry from the world of performance and racing. I have a specific idea for what I want and how I want my LT1 to perform, much like stock, same smooth idle quality, plenty of vacuum, but with the caveat that it can suck in more air than the factory cam and can expel exhaust at the necessary proportional rate. The torque levels I am seeking are equivalent to what a stock LT1 cam produces 1000 RPM higher and producing it 500-1000 RPM lower. Instead of advancing my stock camshaft and relying on higher ratio rockers, why not have a custom grind that further increases valve lift while working in tandem with 1.7 rockers? This is where my logic now stands with all the reading and online resources on camshafts and how to build the right one for your application. Why can't I have a high lift camshaft with a wide lobe separation angle on my LT1? This camshaft is good for the LS7 albeit that engine is a 7.0L with far superior breathing than my LT1 but such a camshaft should be possible for my set-up.

So, with your logic turbocharging my stock LT1 won't net me any power gains? Supercharging my LT1 won't net me power gains? Stroking my LT1 won't net me power gains because the stock heads don't flow as well as LS heads? I beg to differ in your assertion about the LT1. Yes, to get the most out of an LS7-esqe camshaft tailored to my LT1 I will likely need porting to my heads, hell, I would probably be better modifying a cheap set of cast-iron LT1 heads with better flow. I fail to see how allowing the LT1 to suck in more air will not help it yield a torque curve that is a modest improvement over it's stock torque curve.

Shownomercy

iTrader: (1)

I did not say that.

There is little point in hanging a valve open say .6 if the head is well past max flow at .4 I am struggling to see why you think that by just forcing the valve open more, the head will accommodate you and flow some more all of a sudden. You are wasting motion for nothing gained. Furthermore, why do you care what the head flows if you are going to restrict it with a god awful TPI intake? And yes, I know you can in theory trade high lift instead of duration, but that gets into race car land and you don't want that.

You have quite possibly stated that you want to do exactly every thing the internet has said not to do. Iron heads? TPI intake? Lower torque curve to be TPI like? You are either a brilliant troll, or just incredibly stubborn.

Aside, you will get good net gains if you turbo charge it with stock heads. And just think of the wacky boost curves you could dream up to net you max fuel efficiency

Phoenix'97

Ah, better! Okay, the heads won't flow past .4 but what RPM will this level be reached at with the cam I am looking at? Since this is a problem I felt I would likely run into, would 200cc capable heads help remedy this problem and accommodate .6 at whichever RPM level this will happen?

The reason I am attracted to the "restrictive" long runner TPI intake is for its additional torque production from 2500 to 4500 RPM, well beyond what my short runner stock intake can produce. On top of not being happy with my off idle torque, wanting a little more at 1500 RPM than what I currently receive with the stock cam, I am not happy with how flat my torque is on up to 5000 RPM. I don't wish to high rev my car to tap into those higher torque numbers when I can achieve them at mid-range RPM and using the fluid dynamics of the TPI intake. These are the aspects of my LT1 engine and factory set-up that I wish to have changed. If it requires some "race car land" know-how to make it happen then fine but the suggestions I have been given ever since I started asking about cam modifications to my car have not been true to what I am looking for, stock daily driver dedicated performance.

For the sake of ease and the sake of performing this build on a budget, the cast iron B-body LT1 heads which flow 200cc would be something for me to consider as opposed to spending $1000+ per head on the same aluminum aftermarket heads. Again, this is what I need to figure out before hand and whether or not this camshaft idea is doable.