Paul57

Can somebody enlighten me...
Generally speaking, is a cam that is more intake "heavy" (lift & duration) going to be more likely to produce more torque...while a cam that is more exhaust biased is going to be more likely to produce more HP...all other things being equal.
Is this way to general or is there a strong amount of truth to this?

1CAMWNDR

iTrader: (21)

No, it doesn't GENERALLY work like that. GENERALLY a 346" LS1 will make better torque with a cam with duration of 220°-224° on the intake lobe. When you get to 228° and higher you move the torque curve farther up the rev range, that is trade low end torque for high rpm power. Exhaust duration is more dependant on what kind of exhaust you have and its ability to exhale what the intake lobe drew in.

GENERALLY, an LSA of 110°-112° will bring the torque in sooner and more rapidly but suffer (or bless you with---depending on what you like) a rough idle. An LSA of 114° -116° is better for forced induction motors and will usually have a smoother idle.

>>Please note these are gross generalizations to give you an idea of what moving duration and LSA around might do. The best thing to do is decide exactly what you want out of your car (be brutally honest with yourself when you think of this) and get a custom cam spec'd just for you.<<

PREDATOR-Z

The question is do you want more trq? and the sub-question is: Where in the band?

Higher durations will produce more trq, but as duration climb, the valve events (which dictate where the powerband is) will push that trq higher in the rpms. To remedy to that you have to tighten the LSA (along with advance) to have a earlier IVC and bring the band back down.
Basicaly it is a matter of valve events and their relationship to each other. Early IVC and early EVO will produce trq earlier in the band. But as duration increase, so does overlap which could lead to intake charge contamination due to reversion.
The whole trick is to balance all of these valve events while utilising peripheral parts capabilities (intake/exhaust), and that is where it gets complicated and experience starts making it easier to match it all up.

Paul57

Thanks for the information. It is appreciated.
After proof reading my post, I think I misrepresented what I was looking for.
I already have a cam (@.050) 210 int, 218 exh, 114 lsa. It was referred to as a "torque monster" in a magazine build-up and dyno.
My real concern lies in the heads. From the flow data I have seen the (stock) 317 heads flow more on the intake while the (stock) 243 heads flow more on the exhaust.
This is what I really was trying to get an answer to...for more intake being equivalent to more torque. I apologize for not making that clear.
Do you have any clarification on the better head choice?? I am primarily looking for street use and lowest ET possible with this set-up.

slt200mph

iTrader: (42)

a 210/218 split will be a small TQ monster to say the least....... not enough cam no matter what heads you use.

1CAMWNDR

iTrader: (21)

The 317 and 243 heads have nearly identical intake and exhaust ports. The 243 head has a smaller combustion chamber which will equal a higher compression ratio. Get 243 heads with a good valve job and a slightly larger cam of the 224° .600" 112° variety and have more torque and horsepower.

slt200mph

iTrader: (42)

224/228 or 226/230 would be better and if you put either of them on a 110+0 LSA you don't have to wind it up as much.

Paul57

You are correct...it is just a "little fella" cam . When I get home I will try to find the link that called it a "torque monster". It was compared to the stock LQ9 cam and 2 or 3 others that were much larger and still had more torque.
With 243 heads I would be around 11.3 cr on an .041 gasket to keep quench tight.
Is anyone running that much compression on a regular driver with 91 octane??????
I have the tools to open up the combustion chamber but not the knowledge as to how much should be taken off and where...unless someone wants to share some detailed info .

PREDATOR-Z

243s for sure and all LS heads flow more intake than exhaust. Perhaps you meant 243 exhaust flows more than 317 exhaust

In any case the 317 have 71cc chambers and 243s about 65cc.
On a LS1 that would be a significat difference in compession. More compression= more power.

Mark

Paul57

Yes, that is exactly what I meant...according to the data I have seen.

I am probably "splitting hairs" but I was trying to find out if maybe the 317s would be slightly better for more torque from a flow perspective since I am not sure I can use that much compression (11.3 cr with 243s) with 91 octane?? It would be nice to hear if anyone has run that much compression (11.3) on a regular driver with 91 octane. Am I over the limit for pump gas??

There were 6 cams in this test/build-up. Here is the link for the "little fella" torque monster...
http://www.hotrod.com/techarticles/e...camshafts.html

PREDATOR-Z

You could run 11.3 SCR on 91 Octane, given you set your DCR and cam valve events properly.


This is the type of cam I would use if trq is what you are after:

230/228 .612, .588 110-1 LSA

It is a custom grind, needs headers and true duals for best results.

This is what the trq curve looks in a 6.0 in a S10 conversion. cam only with shorty headers.

Paul57

The specs on your cam are why I started this post...because, you are biased toward the intake. Although, I know there is more to it than that...but, I don't fully understand it all, yet.

With this cam (I already have), am I barking up the wrong tree to run 91 octane with 11.3 cr ??
Intake 210 @ .050, .531 lift, Open 5 ATDC, Close 35 ABDC, LCL 110
Exhaust 218 @ .050, .531 lift, Open 47 BBDC, Close 9 BTDC, LCL 118

1CAMWNDR

iTrader: (21)

Yes, that cam you have listed is not much bigger than stock. It is a waste of a cam swap if you ask me. You want something like what Predator listed or slightly less to have an easier time tuning and an easier idle.