LSGunZ28

iTrader: (8)

Why do I see people posting here.

112 LSA will have a lower torque curve than 114 LSA...
It makes no sense.

The General rule of thumb is the tighter the LSA the higher the torque peak is generally moved up.

Why does a 224/224 cam with 114 LSA peak at 6400 RPM and a T rex with 110 LSA 242/248 cam have a peak powerband of 7000 RPMs?

That already goes to show that the bigger cams generally tend to have atighter LSA..

I learned this in my cylinder head rebuilding class, and just to be certain in my engine overhaul / building class when we talked cams again, I asked my auto teacher to verify this. and again he said so... "tighter LSAs move the peak torque curve to higher RPMs.. and it makes sense compare any aftermarket cam and you will see from 114LSA - 110LSA, but the stock LS1 cam which peaks HP way sooner, has a much higher LSA.

So wtf am I missing here? Is everyone here have it backwards or does my professor, whole High Performance Auto program have it backwards? I think I am right, but I wanna figure out WTH is up with this once and for all. Can anyone with much knowledge explain to me the differences to me?

I can understand the operation of a camshaft, Im not new to the Technical world of Automotive, both hands on and reseaching, theory, learning high performance engines, chassis and drivetrain.

But I want someone(s) to come in and explain to me, why I am hearing this from LS1tech constantly.

Thanks.

Higgs Boson

iTrader: (3)

I think you are misinterpreting. From my understanding, a higher LSA will have a wider torque curve and a tighter LSA will be more peaky. Where the peak is depends more on the duration. I also think that you see tighter LSAs with larger durations due to piston to valve clearance issues. A huge duration with a high LSA would cause interference. These are my assumptions. Honestly, cams are my weakness.

LSGunZ28

iTrader: (8)

I may have misinterpreted. if So.. having a tighter torque peak makes a lot of sense. So that clears up what I may have been hearing...

However, Im pretty certain Ive been told the torque peak moves up a few times with a wider LSA and that is just wrong.

ArcticZ28

iTrader: (14)

LSA is hard to say wider does this and narrower does that all the time. You really have to take into account the duration and overlap of the cam. There are a few generalities that can be made that have already been discussed, but it's better to take everything into account when analyzing why one cam behaves different from another.

PREDATOR-Z

It is not the lsa that you look at but the IVC, the IVC will dictate where the cam "peaks"
Lower IVC cam peak sooner, higher> later, this will be affected by rest of intake combo.

BlackScreaminMachine

iTrader: (17)

From personal exp a cam with a Wider LSA (114 over a 112) given the same duration and lift WILL NOT make as much power in the lower rpm range due to the peak moving further up.

We put a Blower spec grind in a N/A motor for a LT1 350 with the expectation of the blower down the road. Welp it didnt happen and the person went from cutting 1.7 60 foots to putting down 1.9's and basically running the same ET even though he gained in MPH. The TQ converter and rear gear remained the same.

That cam make about 40 more hp over stock but since the curve got pushed forward he needed to match it to the converter and rear gear to take advantage of the new found power.

Had he gotten the same grind on a 112 he would have gained in ET as well.

Thats just personal exp and I am no wiz when it comes to valve timing events, ill leave that to Pred or PatG.

LSGunZ28

iTrader: (8)

what LSA does pro stock use? Nascar? just curious...

Beast96Z

iTrader: (21)

In general, a tighter LSA will build more power due to adding extra overlap, but you will "tighten" the band. Widening the LSA will broaden the curve and reduce overlap. This may cost you a few HP, but you may have more average power.

PREDATOR-Z

Take 2 identical cams

TR224/224 112+4
TR224/224 114+4

The 114+4 will make more Peak HP, but the band is higher in rpm (about 200) and broader.
The 112+4 will make a bit more power under the curve, power starts sooner (about 200 rpm) but dips faster after peak, less peak HP.

So this is all related to VE (valve events), and not just LSA.
Sooo one needs to look at VEs and NOT just say X cam on 114 is less powerful than Y cam on 112 etc....

JPH

iTrader: (2)

prostock is 114 or so, nascar? changes at every track i bet. but there cam profiles usually are so big, they have to be that wide, or overlap is stupid big.

LSGunZ28

iTrader: (8)

why did i think Ive seen numbers in the low 10xs? before? at least in prostock.

LSGunZ28

iTrader: (8)

so in that case, since Im a DD, Id rather have the 112 LSA.

axles of evil

depends what you like. the 112 lsa will also TYPICALLY have a choppier idle. however i have seen a few cars on 110 and 112 that idle like a car should stock, so that is also subject to other cam specs etc.

stock LSA on an ls1/2/6 is something like 116-117 for what its worth.

Asmodeus

overlap and valve events

dmc454

A couple weeks ago I measured a Ford NASCAR cam & it came to 110 LSA &
duration at .050 was 266 int & 270 Ex . Cam lift .399 lift & .410 EX with a
rocker arm ratio of 2.1 int & ex.Valve lift was .837.9 intake & .861 EX .The person said it was used at Charlotte Motor Speedway.He said it had a rpm range of 6500 to 9500.There are a lot of NASCAR engine builders here and from asking around they have experimented with 100 LSA for brute low end TRQ to 115LSA for top end HP. Im no engine builder but learning all I can from ever one here.Hope that helps

LSGunZ28

iTrader: (8)

well the Tv3 I ordered has 111ls1, I would have went for 112lsa to have a less choppy idle.

i prefer a wider rpm range of torque and lose a few peak hp, than having a peaky cam only. of course only due to my car being a DD.