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Truck 5.3L with LS7 cam

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Old 08-12-2007, 04:02 PM   #1
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Default Truck 5.3L with LS7 cam

I recently just bought a truck 5.3 and i was wondering what it would take to install a cam from an LS7. Any info would be greatly needed. Thanks.
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Old 08-12-2007, 04:56 PM   #2
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I'm far from knowledgable about the LS7 cams, but I know an LS2 cam won't work in an LS1 car due to the differences in cam position sensor placement.

Not sure if that would be an issue going from an LS7 (Also Gen IV like the LS2) to a Gen III motor.
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Old 08-12-2007, 06:13 PM   #3
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It can be made to work, and now that the search is working a little bit better, said search will yield some results. Items needing to be changed to run the LS2 or LS7 cam will be front cover, LS2 style timing set, cam sensor extension harness, and plug rear cam sensor hole.

That LS7 cam is HUGE for a 5.3L motor! What stall, gear, supporting mods, etc do you have? What ar your plans for the truck? All race, all street, a mix, etc?
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Old 08-12-2007, 08:34 PM   #4
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I have a 02 camaro 6 speed trans. i want to make this a fun street truck. i was wanting to put a z06 cam in it and i found one on corvette forum out of an LS7. I know i plan on doing a better cam and hard valve springs. Any recomendations?
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Old 08-15-2007, 09:41 AM   #5
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What if i now choose to go with a cam out of a LS6. would that work without have to change those things other than putting different valve springs?
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Old 08-15-2007, 09:49 AM   #6
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You can make the LS7 cam fit, but the very high intake centerline and very late intake valve closing point would put the dynamic compression in a small 5.3L into the toilet. You would actually go slower with the LS7 cam in a 5.3L truck. Obviously, there are much better choices for the 5.3L, but I don't think the LS7 cam is one of them.
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Old 08-15-2007, 11:48 AM   #7
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The LS7 cam will not be happy in a 5.3L.

It's a 210/230 .561/.558 120LSA w/ 1.7 rockers. There is a lot of split to compensate for the "poor" flow of the exhaust ports and manifolds of the LS7. I'd go with a cam more custom tailored to a 5.3L or go with a LS6 Z06 cam.
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Old 04-19-2016, 12:04 PM   #8
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Quote:
Originally Posted by Patrick G View Post
You can make the LS7 cam fit, but the very high intake centerline and very late intake valve closing point would put the dynamic compression in a small 5.3L into the toilet. You would actually go slower with the LS7 cam in a 5.3L truck. Obviously, there are much better choices for the 5.3L, but I don't think the LS7 cam is one of them.
What about advancing the cam 8?
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Old 04-20-2016, 09:40 AM   #9
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Quote:
Originally Posted by danielblackst1 View Post
What about advancing the cam 8?
You do realize that you just revive a post that's almost 9 years old, right?
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Old 04-20-2016, 10:16 AM   #10
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Quote:
Originally Posted by danielblackst1 View Post
What about advancing the cam 8?
Quote:
Originally Posted by JoeNova View Post
You do realize that you just revive a post that's almost 9 years old, right?
An oldie but as goody.

Anyhoo. To answer your question Daniel, since the camshaft has such a wide lobe center angle, when you advance the camshaft to correct the intake valve events, you end up with a exhaust events that are much too early.

As Patrick said, the build will do much better using a camshaft designed for the application.
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Old 05-18-2016, 07:18 PM   #11
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Quote:
Originally Posted by speedtigger View Post
An oldie but as goody.

Anyhoo. To answer your question Daniel, since the camshaft has such a wide lobe center angle, when you advance the camshaft to correct the intake valve events, you end up with a exhaust events that are much too early.

As Patrick said, the build will do much better using a camshaft designed for the application.

Yeah but i have an ls7 cam I bought for 100 bucks lol i ran the ls9 cam in my ls1 advanced 8 and it did pretty damn well imo lol 98 firebird with stock long block.

So what about an ls6...? Would it not benefit from a few degrees of advance? Lol
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Old 05-18-2016, 08:45 PM   #12
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Quote:
Originally Posted by speedtigger View Post
An oldie but as goody.

Anyhoo. To answer your question Daniel, since the camshaft has such a wide lobe center angle, when you advance the camshaft to correct the intake valve events, you end up with a exhaust events that are much too early.

As Patrick said, the build will do much better using a camshaft designed for the application.
Without having the valve events in front of me, who's to say. I'm pretty skeptical until I see proof. Based on my comparisons it seems to me that most PD cams have a late ICL and still have familiar specs from there on. Whereas a NA cam can have similar specs and have an early ICL. So seems to not add up when you say the exhaust events would be too early.

When i was installing the ls9 cam in my ls1, which is very similar to the ls7, i asked about the 8 of advance in a post and i got my 'go-ahead' when the Cam-Motion owner/op, whatever, said it should help this cam [ls9] quite a bit. Yes was a cathedral port engine which the duration split isnt optimal, but still, it worked! Lol id be interested to see how it would have done on Nitrous too! Lol

It really came down to:

1. The ls9 cam was 130 bucks

2. My friend had a seized gen 4 5.3 he bought for the heads and sold me the remaining short block for $20. Haha

3. I was brave enough to cut into my harness and re-route the cam sensor wires through another leg of the harness and get it all to work lol

That was a 5.7, now i have a 5.3 in my truck with the ls2/peanut ls6(if im correct) and for ***** and giggles was going to advance the ls2 from its 112 ICL to ....? Havent decided yet. 108 was my gut number. I get 112 from doing google searches so some people could have been wrong. I could degree it but that takes time i dont have at the moment haha
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Old 05-18-2016, 10:03 PM   #13
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You can always advance or retard a camshaft and change it performance characteristics. As long as you have enough valve clearance, go for it. Just don't expect and LS7 or LS9 camshaft to make the power of a properly chosen performance aftermarket camshaft. That is all I am saying. Have a look at this article. It compares all of the factory cams, then look at the 3 aftermarket cams at the end. I think you will find that a properly chosen aftermarket cam is going to make more average power over a wider range.
http://www.hotrod.com/how-to/engine/...st-comparison/
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Old 05-18-2016, 11:06 PM   #14
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For the more technical minded, I will explain why the wide lobe center, late intake centerline OEM camshafts don't make as much average power as a properly chosen aftermarket performance camshaft.

To get started, lets look at the valve events of the LS7 cam:

Specs@ .050":211-230 on 121 LSA
Intake Valve Open: 15 ATDC
Intake Valve Close: 46.5 ABDC
Exhaust Valve Open: 56 BBDC
Exhaust Valve Close: 6 BTDC
Overlap @ .050" = -21

If you have a lot of familiarity with the valve events of performance camshafts, one valve event above really stands out. That is the intake valve open of 15 degrees after top dead center. That valve event right there is what is hurting the overall performance of this camshaft the most. If you were to change just that valve event from 15 degrees after top dead center to a much earlier "0" degrees, this camshafts performance would increase dramatically.

Opening the valve earlier would help feed the engines cylinder much more efficiently. The reason for this is that, like most domestic V8 engines, the LS engine will reach peak piston speed on the intake stroke at about 70-75 degrees after top dead center. Once you compare this to the LS7 cam's intake centerline of 121 degrees, you can see that the engines cylinder is at peak demand 50 degrees before the camshaft reaches peak lift. This dynamic right here is one of the main reasons that aftermarket performance camshaft open the intake valve sooner. It allows the valve to be open further when the engine wants the air and fuel the most.

So, you say lets just advance the LS7 camshaft. You can. And it will help low end power by getting the valve open sooner to feed the engine at peak demand and closing the the intake valve sooner to help trap more cylinder pressure at lower RPMs. But, it will also open the exhaust sooner which may waste some torque at low RPM and close the exhaust valve sooner which will diminish final cylinder evacuation at the end of the exhaust stroke leaving behind more burned air and fuel to contaminate the subsequent intake stroke. On top of that, the LS7 camshaft will still lack overlap compared to an aftermarket performance camshaft which results in less upper RPM power. Let's look at the valve events of the LS7 camshaft advanced and highlight the positive effects in green and the negative effects in red:

Specs@ .050":211-230 on 121 LSA +6
Intake Valve Open: 9 ATDC
Intake Valve Close: 40.5 ABDC
Exhaust Valve Open: 62 BBDC
Exhaust Valve Close: 12 BTDC
Overlap @ .050" = -21

As you can see, the intake valve events have gotten better even though the intake valve open is still late compared to a proper performance camshaft. However, the exhaust events have gotten more out of line. The most detrimental would likely be the very early exhaust close of 12 degrees before top dead center.

Now, lets go in a different direction. Let's take that LS7 cam and change just two valve events. We will change the intake valve open and the exhaust valve close to "0" degrees at .050". This is what we would get:

Specs@ .050":226-236 on 115.5 LSA
Intake Valve Open: 0 ATDC
Intake Valve Close: 46.5 ABDC
Exhaust Valve Open: 56 BBDC
Exhaust Valve Close: 0 BTDC
Overlap @ .050" = 0

As you can see, this new revised version of the LS7 camshaft would still have 0 degrees of overlap at .050" which would make for a very nice driving performance camshaft with a mild idle and good drivability and would probably rip pretty good.

Some may be tempted to ask why GM doesn't do this. The reason is that even though us automotive performance enthusiasts would find the idle and drivability totally acceptable with this cam, GM requires and even smoother idle, less emissions and more engine vacuum. So they trade performance to achieve their standards.

Lastly, lets look at a performance camshaft that you could use instead of the LS7 cam that will outperform it from idle to redline:
Cam Motion Titan II
Specs@ .050":221/226 on 112 LSA
Intake Valve Open: .5 BTDC
Intake Valve Close: 40.5 ABDC
Exhaust Valve Open: 47 BBDC
Exhaust Valve Close: 1 BTDC
Overlap @ .050" = -.5

The Titan 2 camshaft still has -.5 overlap, so like our revision to the LS7 cam above, it will have great drivability and would be very comfortable as a daily driver camshaft. However, take note of the intake valve close event. It is 6 degrees earlier than the LS7 camshaft. This will allow the Titan II camshaft to capture more cylinder pressure at low RPM and make more torque sooner than the LS7 camshaft. And, even though it has an earlier intake valve close, it will still make more power in the upper RPMs because it will fill the cylinder so much more efficiently at peak demand on the intake stroke. Then throw in the additional power that is created in the upper RPM due to the additional overlap, and it is just superior across the board.

This is why a properly chosen aftermarket camshaft out-performs the OEM performance engine cams like the LS7 cam.
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Old Combo, SBE LQ9 Best N/A ~ 10.86 @ 123.15 ~ 10.04 @ 133.35 on spray ~ 10 second pass track video

Last edited by speedtigger; 05-18-2016 at 11:20 PM.
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