BRD-PREY

iTrader: (5)

I have noticeted that the LS3 cams have a large split duration sometimes as much aas 12 degrees, is the reason because of the Intake to Exhaust ratio of the square port heads is larger apart than the Cathedral port heads of the original Ls?

Thanks,
Trying to look at cams for a LS3 416 that match my heads.
DAILY DRIVER! really 135 Miles a day 4 days a week+
Low end power 1600 rpm
Valve train longevity is a concern.
I have Mamofied AFR 205's with 8019 springs, (getting Mamofied Fast) on top of HKE LS3/416 exiting out of QTP LT's.
I want the power down low but don't want to leave any HP up top on the table I don't have too.
The Engine will have 11.2/1 compression, 62cc heads, -15cc dish Wiseco, Decked .009 with .041 head gasket
These are my flow Number:
Intake Exhaust
.200....158 .200....130
.300....222 .300....185
.400....267 .400....223
.500....296 .500....240
.550....304
.600....300 .600....247

I was thinking of 238/242 113 +2 and .600 lift on a Lsr lobe.

Thanks Ed

davidws6

iTrader: (36)

The flow on those heads are almost the same as what I had on my 317's that I stuffed on my 402. I went with a 231/237 115LSA +2 Fast 90/90 and it popped 482 rwhp. After that, SD tune n it came alive !

That 238/242 might be a good choice.

ChucksZ06

iTrader: (9)

There is a great cam comparison in the new issue of gm High Performance magazine. Shows how the overlap directly effects the vaccum and power production.

BigRich954RR

iTrader: (1)

Cam looks pretty good i might tell you to make it a little smaller 232/242

BRD-PREY

iTrader: (5)

Why do the cams for the LS3 have such a big split, 10 degrees?
Ed

Patrick G

iTrader: (14)

Because their huge intake ports flow so much air, they can make the same power with a much smaller lobe. Also, too much overlap causes the exhaust reversion to spoil power. The big splits are not because the exhaust is bad, but because the intake is so good. Your 238/242 cam will work nicely.

WSsick

iTrader: (13)

you might as well just go to Pat G for your cam. those big cbues would love a bigger cam, and im sure he can get you one that drives like a small cam!

99blancoSS

iTrader: (115)

Why not have Erik spec your cam for you as well, he builds some of the fastest cars on the boards when he does the long block. He will give credit to the tuner as it doesn't work if the tuner is not good, but he is very well qualified to spec the cam and has great success with his combinations.

To many cooks spoil the broth and if you have one person doing one thing and another doing something else then you can get mixed results that might not be as good as they can be.

BRD-PREY

iTrader: (5)

Thanks for all the advice. I've been in contact with Eric about my cam as well Tony.
I would never just pick my cam. But I wanted to look at it and see how close I was.
I believe the heads are the biggest part of getting the right cam. I mean outside of the drivers intended use. With that being said, I figured I needed someone who has experience with spec'ing the AFR 205 on to a stroker but more important (not just a maximum output motor) as this is a daily driver. I also know that with that many cubes and those smaller runner heads the low end is going to be there and that means that the secret will be not letting the torque fall off to fast after peak.
So Eric certainly would be a good choice but in our conversations he stressed most of his expertise was High rpm motors and or Big HP (I hope I'm not misinterpreting him). Tony did mention the few cams he spec'ed for some strokers he built.
I was going to contact Patrick, I have seen by his posts he's familiar with that head and works with Tony on stuff, the $25.00 is no problem but I had a few questions.
I just might be over thinking it(as I often do) but with my combination the cam could really be difficult to spec. if I want to maximize the motor. The fact I will be using the small runner head I think provides it own unique challenges.

Patrick I understand the intakes are large on the square port head but what kind of velocitys do they have? I was wondering if the exhaust valve had to be left open longer to help scavenge as the velocity of the incoming charge might be lower than on the cathedral head?

Ed

99blancoSS

iTrader: (115)

Well don't let it mislead you, he does a lot of "real" racing engines so that would be why he said that. (that and he is being modest) We just did a combo for an 01 Firehawk with 205's on top (milled and spring upgrade) and a custom cam from Erik. Was a 231/235 but car had 410's in it as well. Stock bottom end.

I can help you get a proper cam spec'ed and ground from Comp (would be HKE specs) or you can have him do it but that is who I would go with, just to keep it all complete from one person. One point of failure is another way to look at it

Nothing against anyone else at all. In this case I would have the guy building the engine spec the whole combo .. considering his credentials I don't see how you can go wrong.

slt200mph

iTrader: (42)

Tony and Patrick know their stuff .... that sould be a fun DD ... please let us know how it goes.

racer7088

I do l like spec'ing cams on the more race oriented stuff I do like Chris says. I am also perfectly fine with Pat G or Tony spec'ing something for the street realm as I know Patrick especially really tunes these things as well and has some good ideas about the true drivability that are directly based on his own tuning experience which I certainly trust.

Also Patrick G can come up with a cam per his service and you can have Chris grind it through us as well or on some Patrick uses Geoff at EPS whichever is best depending on what lobes he uses.

BRD-PREY

iTrader: (5)

This is the recommended Cam, its on the Cam grinder as we speak. thanks for everyone's input.
Ed

Cam recommendation: 2001 F-body with forged 11.2:1 416 short block, Mamo ported AFR 205 heads, Mamo ported FAST 90 intake, M6, 3.73 gear, 1 3/4” headers with no cats, 6500 shift point, 6800 rpm rev limiter.
238/246 .604”/.607” 115LSA +4 advance (with 1.7 ratio rockers)
Comp EPS/EPS lobes 54-000-11 3 bolt cam core
13120R/13122R HR115LSA +4 advance (111 installed intake centerline)

Cam Valve Events 0.006 0.050 0.200
Intake Duration - ID 287 238 158 13120R EPS lobe .604"
Exhaust Duration - ED 295 246 166 13122R EPS lobe .607"
Lobe Center Angle - LSA 115 115 115
Intake Centerline - ICL 111 111 111

Intake Valve opens - IVO 32.5 8 -32 BTDC (- indicates ATDC)
Intake Valve closes - IVC 74.5 50 10 ABDC
Exhaust Valve Opens - EVO 86.5 62 22 BBDC
Exhaust Valve Closes - EVC 28.5 4 -36 ATDC (- indicates BTDC)
Exhaust Centerline - ECL 119 119 119
Overlap 61 12 -68 degrees