Bigmike4098

For a ls1 with ls6 heads, and ls6 intake. whats the biggest cam that i can put in it?

HCI2000SS

iTrader: (2)

Stock ls6 heads? When you say biggest cam do you mean concerning PTV clearance?

soloman369

iTrader: (13)

Yay another one of these threads!

Bigmike4098

Yeah stock ls6 heads stock everything. But just the cam swapped.

Darth_V8r

iTrader: (4)

Depends on what else you're willing to do. Springs, pushrods, etc. if you're just wanting to swap the cam and no other work, then put a cam motion drop in cam in and be done with it.

If your willing to do springs, lifters, fly cut the Pistons, etc, you can put in a very large cam.

Oh, and to have any kind of success with a cam swap you better also do long tubes if you haven't already.

Bigmike4098

Ok with out doing anything to the lowerend, just top end work. What can i or should i do to get the biggest cam i can?

Bigmike4098

Im new to engine building. You mean long tube headers right?

HCI2000SS

iTrader: (2)

Just so you know the biggest cam will not perform the best in your case because you don't have the right supporting mods. You understand that right?

Bigmike4098

Im not really looking to get the max power out of it. Im looking for the sound of it. For now anyway. I plan to build it as i go later on.

HCI2000SS

iTrader: (2)

For max sound throw in a cam like the old t-rex cam with a cut-out. A friend of mine has that exact combo on his LS1 Z28 and it sounds like a frigging drag car with the cutout open lol

Darth_V8r

iTrader: (4)

Yes I meant long tube headers. If you cam a car, you need the long tubes to prevent a ton of other issues. Also, off my phone I do t see signatures but if you're an automatic you will also need a higher stall converter to address the low rpm off idle surging that comes with a larger cam. When I did my first cam upgrade, I had about a dozen people off this site tell me to do the headers first. And they were absolutely right. Headers dramatically change the sound vs stock manifolds but also open it up in preparation to support more power.

As to the cam, if you're willing to do springs and pushrods, the tick performance torquemax V2 will give you a really good chop and make decent power.

If you're wanting to only do the cam and nothing else, then get the cam motion stage 4 LS1 cam.

One other thought for you - a cam has its distinctive sound because it creates a vacuum leak at the valves. You can make a choppy surgy idle by unplugging a small vacuum line or by tuning your idle speed low and making the timing overcompensate.

Bigmike4098

Well this engine is going in my 280zx. So i dont have much room for longe tubes. And i was thinking of working the heads, And opening them up. With. Some roller rockers and roller lifters. And i do plan on some cutouts right at the headers.

Darth_V8r

iTrader: (4)

LS engine lifters are factory hydraulic rollers. And you would need to pull the heads to get to them. No big deal, just preparing you. Not like the old small blocks. You should do heads and cam at the same time.

The problem with factory manifolds with even a moderate cam is reversion. While both valves are open at the same time at TDC (overlap) the gases will flow either from the intake manifold to the exhaust or from the exhaust manifold to the intake. This backwards flow is commonly called "reversion" and you can probably imagine the list of problems this can create. Long tube headers will naturally stay at lower pressure vs the intake manifold due to the primary tube length and exhaust gas velocity creating a vacuum wave behind the gas pulses. The stock manifolds will be slightly pressurized vs the intake due to the low gas velocity and short runners. Another cylinder will be pressurizing the manifold at the same time you're counting on the exhaust to help cylinder filling during overlap. It's very hard to describe but once you see it in your mind it makes sense.

If you don't have room, you don't have room. But be careful on cam selection or you'll find stock cars outrunning you

Bigmike4098

I plan to put a set of shorty block huggers. Or do that make longe tube block huggers. And thats cool bout the stock rollers. Teach me of great one.

Darth_V8r

iTrader: (4)

lol!! I appreciate the love but there are tons of guys on here better than me.

In truth I don't know if the shorties will help with the reversion. Probably the best person to talk to is either Martin Smallwood or Kip Fabre. Those guys can give you an idea of a cam that will go well with your configuration. Martin is the owner of Smallwood racing development and Kip is with cam motion.

If you're going to get into the heads, Tony Mamo is about the best. All three of those guys are users and excellent resources.

Most of us on here - like me - are used to everyone running long tube headers.

Bigmike4098

Well i plan to drop in the ls1 stock then bolt on the new heads, intake and cam later when i get them. I may have to make my own header to make it run right. That will take a long time. Lol

Martin Smallwood

iTrader: (2)

Long tube headers will greatly improve scavenging over a shorty header. In fact, the shorty header will most likely create even more reversion at low engine speeds versus a long tube.

Reversion has to do with harmonics in the exhaust system that are created by pressure pulses. When those pulses reach the end of the collector, based on primary length, primary diameter, collector length and diameter and a whole myriad of other things like valve overlap (i.e. when the intake valve opens and exhaust valve closes).

Other things like intake runner length and intake port velocity can help or hurt reversion.