JakeFusion

iTrader: (7)

Finally, someone with sense.

If you drive a car with a 224/228 110 it will drive and idle better than a 234/238 114 if the cam lobes are of the same family. OMG HOW>!?!

Overlap. Overlap is power and it also means a shittier idle and more difficult to tune. The 224 cam has 6 degrees of overlap at .050" of lift (since I mentioned the numbers at .050", I'll discuss overlap there - but idle quality is determined at .005" of lift FYI). The 234 cam is at 8 degrees of overlap despite the 114 LSA, which means it will idle nastier (assuming the lobes are the same so the difference at .005" will be 10 degrees as well).

But the key to making power earlier or later or blah blah, is the IVC (or intake valve closing point). The earlier the IVC is, the lower the peak will be and the more torque it will make. There are two ways to get your IVC lower - one is to ground in advance, but I don't like that as it kills power after peak, meaning you can't rev say 500 RPM past peak to really lower your ET.

The other way is to ground the cam on a tighter (numerically smaller) LSA. Unfortunately, a tigher LSA will produce more overlap with all things being equal. It creates more cylinder pressure and more power, though too. And if the IVC is not too low for the manifold, it will keep peak numbers up as well.

The LS1 likes an IVC around say 44-46 degrees (a nice number for a 346 with the LSx style manifolds for a ~6300 peak). Using the earlier cam combinations, the 234/238 on a 114 without any advance has an IVC of 51 degrees. A little high for an LS1 if you want optimum valve events for 6300 peak HP and 4800 peak torque. It also kills the dynamic compression, or cylinder pressures created, because the IVC is too late without really ratcheting up the compression to 11.5:1+ (again this depends on the cam lobes and that number at .005" or advertised duration).

The 224/228 110 with no advance is around 42 degrees, so it will produce more low end grunt and fall just short of 6300rpm peak. Going to a 112 or a 114 puts the IVC at 44 and 46 respectively. These were some of the first LS1 cams and they worked because the valve events were right. What happened was most people learned about them and knew about them. So as larger and larger cams came out, the LSA was usually kept in that 112 to 114 range. Now there are theories on where the LSA needs to be when stroke and headflow are put into the mix, but that's too much here. Know that the 112 would idle worse than the 114 and create better lowend. The 114 would idle better and pull higher. Both would pull very cleanly because they have no advance (though sometimes advance is good to overcome weak exhaust flow for example).

If I were to run a 234/238 in an 346cid LS1, I'd run it on a 110+1. That puts the IVC at 46 and allows it to nicely pull past peak. The only problem is, the overlap is 16 degrees. In my experience, if you cross 14 degrees, you have better have an awesome tuner or drivability will suffer.

Most off-the-shelf cams are under 14 degrees of overlap @ .050". Most have 4 degrees of advance ground in, because once you break into the 230s duration, your IVC really needs to be around 109-110. The problem is, an LSA of 109-110 is going to produce rough street manners. So it's a compromise to give you the big donkey dick cam without sacrificing the drivability of it. But the real compromise is the amount of power made. A 234/238 at 109 LSA or 110 LSA will make more power in these engines than a 234/238 at 114.

5_02ls1

iTrader: (20)

^^^^^^^wow we did not know that....wow

What part of this didnt you read???
"'m going to pickup a 228R cam "
on a 112 it would have 4* of overlap on a 114 0* both will have a nice lope but the 114 will pull up higher and the 112 will start makin power sooner.......yes lsa is a by product but when the same cam 228ris being used the lsa plays a good role in the powerband.....

TopFlite

I vote 112 since it peaks sooner, which will in turn be better for street use.

HitmanLSX

Guess I should've added at idle, the videos on my youtube in my sig are all with the cutout open but they're all street pulls. Thing sounds nasty when you open the cutouts up. My fiance calls it the vibrator cuz the passenger side dumps out right under her seat lol. I'm thinking about switching just to a GMMG exhaust though.