Summitracing

Answer to the first question. Yes. What did we miss!?

grubinski

OP needs to street drive a 4" stroke LS2 in CA, so wants 0 overlap or something that will pass a sniffer. What cam?

Corona

Wow that's A deep question but it's Really not..🤔

Burn the gas ⛽ Early?

I'm Betting the Farm ......👍

Corona

Complete burn = matching the Compression?
With the amount of Duration so As to have a good Cranking compression While not 🚭 allowing BS excessive Gas blow Bye to Reach the Catalytic converter aka 02 sensor? 91 octane in Cali 🤔

Idk🤣😂 never did get camming 😭🤣😂🙂 Call it in 2 Steven/Bobby @ Cam Motion > or PM 👍 Darth 4 a mini 🐴 = Donkey D cam. Main thing is your octane Regulation @ 91 and compression 🤫

Bortous Where U @........Early burn camming needed 🙂

raidersforever01

Most off the shelf cams seem to want overlap. If i wasn't in cali they would probably work fine but decided to do what some of you said and have one of the pro's spec out a cam and see what they recommend.

LSX416ci

I did an LS3 416 stroker and it was amazing I miss it. Had all the goodies TEA Trick flow 225 heads had them open them up to match the build along with the ported fast 102 intake and Nick Williams 102TB. Ed Curtis did my cam and it was a version of his LSx "HELLION" Hydraulic Roller Camshaft
Specs: 244*-248*-112*-.631"-.631". Put down 530+ho and 510+ tq on a mustang dyno

grubinski

I'd be curious to see what's recommended.

raidersforever01

226/232 118+4 LSA even less overlap then the recommendation i got from everyone. I was thinking something around 0 also but -7 it is.

Bspeck82

Because not everyone knows what they are talking about. That cam sounds perfect for your situation. Pair it with a decent exhaust for a sleeper.

raidersforever01

Yeah looking at the specs it definitely sounds exactly like what i wanted. I was looking at the ghost cam or tsp 228/232 on 115 lsa which looked like as close as i could get off the shelf. Glad some of the guys here put it in my head to go custom.

grubinski

LSA is 118 ... +0? +1? +2?

That should be a super smooth, nice cam to drive on the street.

G Atsma

0 advance gives him 51 IVC. Not sure where his should really be.

QwkTrip

iTrader: (23)

I got no recommendations, just got a question. Which is the real problem that needs to be addressed with a stroker?

1. Stroker needs a longer duration cam
2. Stroker needs more air

Seems like some people are actually arguing like (1) is the fundamental issue, instead of (2).

I was under the impression a longer cam is a crutch for heads that don't give the larger engine the air it needs in the same degrees of rotation as it did with the smaller engine. Put the right heads on the stroker and cam duration gets shorter to do the same job. In other words, when building a stroker the smart money goes in the heads, right?

QwkTrip

iTrader: (23)

And I've got another question for you guys that have spent a lot of time trying to understand cam selection.

What exactly are you focusing on when choosing IVC event? Seems like people often come up with answers down to the gnats *** and I'm curious how you arrive at those numbers. I've never dug into cam theory but I'm starting to get more curious about it. Are you applying some kind of rule of thumb for where in the crank movement you get optimal cylinder fill? And then anything beyond that number is just fine tuning DCR? (I suppose ideally you would fine tune DCR with piston and avoid pushing air back out of the cylinder.)

Same with exhaust duration, how do you guys come up with those numbers? And what rule of thumb are you using for how exhaust overlap effects IVC event?

spanks13

iTrader: (5)

OP specified ported 799 cathedral heads which in my mind turns your point #2 into point 1.

IVC is a balance between managing cylinder pressure, high rpm breathing, and reversion at low rpm. Generally the later the IVC the higher you can rev it and the more power you make at higher rpm ranges, the worse low rpm efficiency and performance, and less dynamic compression

QwkTrip

iTrader: (23)

Yes, but how are people coming up with specific numbers? Do they actually know how to do it from scratch, or do they just have a reference catalog of what they've seen work?

I see threads where somebody says IVC should be xx°, and then somebody else will come in and say, no, it should be (xx+1)°, and the first guys says, yeah, that would be better. How the hell are they able to decide down to that level of detail?

raidersforever01

Advance is +4 making IVC 47

grubinski

I think people have learned from experience what works in what size engine. I think the underlying physics is that a bigger cylinder will create a lot more intake velocity as the piston heads to BDC, and therefore the intake flow will have enough momentum to keep flowing into the cylinder a little longer even as the piston starts coming up from BDC. For best high rpm breathing and best power, you can hold the intake valve open a touch longer. The conventional wisdom earlier in this thread was that ~50 ABDC IVC was "usual" for a stroker.

I think the slightly earlier IVC of this cam is done to help with driveability (and maybe emissions) at lower rpm and load. Or since it's a street car, the OP may have told the cam guru that he'd trade top end horsepower for manners and midrange/low end. Earlier IVC even than this would start to cause the dynamic compression to be too high given the 11.x static compression that will probably be where this engine winds up.

The +4 advance on the cam got us to 47 IVC from the 51 that it would have been with zero advance. It also ensured that during the overlap period, the intake valve is open a lot further than the exhaust (EVC 6 BTDC, IVO 1 ATDC). Not sure if this is intentional for pseudo-EGR, or what... but for sure you're going to be sending less unburned intake charge down the exhaust pipe.