Xtnct00WS6

iTrader: (8)

Question 1: What about a 114 LSA as apposed to 112 LSA makes it better/recommended more often for Automatics?

Question 2: What factors dictate a + 2 advance as apposed to a + 4 or even going straight up? I'm assuming it's just a comprimise between all out racing (0) and street performance (+4) and is "setup specific".

I'm trying to decide on some new cam specs, but I'm caught on what LSA and Advance I want. I have an M6 now but will have a 4l80e in a few years. I'd like a cam that would work well for both setups if possible. I have a feeling that I'll get the answer "just change it later when you get the auto".

Current Setup: M6, TR 224/224 114, Patriot 243's milled .010 (63.02cc) 2.02 and 1.57 valves (they flow a little bit more than 300 at .600 lift), .045 Cometic gasket, and normal bolt ons. 401 hp/ 392 tq on a Mustang Dyno.




This is about what I'm thinking: 230/234 .612/.598 111LSA and +4

Question 3: If I change the +4 to +2, the DCR drops from 8.62 to 8.48. My current DCR is 8.51. Is this drop in DCR worth the extra power up top compared to the extra low end I'd have with a +4 Advance?

Question 4: Can I get the LSK Lobe of 232 and .643 lift changed to 230 and around a .620 lift? That's possible right?

Thanks!

thehammer69

iTrader: (2)

1. I will leave question one to the automatic guys...I have only owned one automatic having vehicle in the last 18 years and that is my diesel truck.

2. Proper VALVE EVENTS and DCR dictate cam timing. You just don't advance or retard based on street or strip.

3. see answer to number 2...if the valve events are wrong at +2, you may lose power up top also.

4. no, that is not possible. You only can choose an existing LSK lobe in Comp cams catalog, and what you asked for doesn't exist. You however could use XFI lobe number 3036 to come close to that 230 but with about .600 lift.

Hammer

Xtnct00WS6

iTrader: (8)

In regards to your answers for 2 and 3 the cam sticky says - Most off the shelf cams have 2 or 4 degrees of advance ground in. This lowers the power band slightly and offers more low end and midrange at the sacrifice of a bit more top end power

- For cams used primarily on the street the advance is best appreciated. For a strip or racing setup 2 or 0 degrees advance will net you more peak power in the upper ranges of the power band

Hammer, you'd suggest staying with a +4 to keep the DCR up and take a small sacrifice to the top end power?

For question 4, you can't have a custrom grind based on an existing lobe? How did you get a 223 duration intake lobe when Comp only has a 224? You also have more lift than the comp cams LSK lobe of .636. How did you get .637?

thehammer69

iTrader: (2)

I can't answer you if +4 would be the better choice than +2. I'd have to know the cam specs and then base my opinion on valve events and a few other factors.

As far as your question about my cam and LSk lobes. LSK lobes are actually advertised in odd numbers...that is why mine and Pat G's are 223/227. You can't have the lobes cutomized...you only can have a cam itself custom ground with the lobes you choose to have it ground with.

Well I take it back, i'm sure you can design your own lobe, but it will no longer be the same ramp rate as an LSK. a 223 lobe at .636 is no longer an LSK if you have it changed to a .620 lift. I'm also sure that it will cost you a pretty penny to design your own lobe.

An as far as the .636 versus .637...there is no difference...I can't even remember why it is even .001" off.

Hammer

ArcticZ28

iTrader: (14)

ICL and advance should only be used as a compensation to get your valve events happier once you decide what duration and lift you want. If you spec a cam correctly, you won't need more than 1 to 2 degrees of advance. The ones that come off the shelf (aka TR224) mostly have 4 degrees of advance to counter most people's attempts at overcamming their car (too high of duration for the powerband they want).

JPH

iTrader: (2)

I like my a4 cars to be 112+3
112lsa/109icl.

Xtnct00WS6

iTrader: (8)

Thanks for the reply. These are the cam specs I'm thinking about. 230/234 .612/.598 111LSA and +4
ICL of 107

Xtnct00WS6

iTrader: (8)

I'm not sure what you mean by that. A TR224 is by no means an overcam. You're saying adding advance is used to compensate for duration? That's kinda what my impression is too. I'm just trying to find that fine line.

white_camaro

iTrader: (13)

whats would be the difference between two cams with these lsa/advance specs?
112lsa+4
110lsa+2

both have an icl of 108 so how would they differ?

Xtnct00WS6

iTrader: (8)

112lsa+4: overlap of 8 at .050
110lsa+2: overlap of 12 at .050 (this will sound lopier)

The valve events are different too.

thehammer69

iTrader: (2)

how can you know the overlap if you don't know the specs of the rest of the cam? I can show you cams that have 112lsa and 110 lsa with negative overlap at .050".

Hammer

thehammer69

iTrader: (2)

take the difference in LSA and multiply by 2. This is the amount your overlap will increase or decrease with a change in LSA.

Example:

my 223/227 cam is a 114 and we know it has -2 overlap
Pat G's 223/227 is a 110 and we know it has 6 overlap.

So it's obvious that we have 8 degrees difference of overlap because we already know the overlap for each cam. But if we didn't know the duration specs, we still would know there is a 8 degree difference in overlap based purely on the difference in LSA. 114-110=4......4*2=8.

Hammer

Xtnct00WS6

iTrader: (8)

Haha...good point. I just assumed he was asking about the cam specs I was using. Bad assumption.

ArcticZ28

iTrader: (14)

Well, they have to use a blanket "fix" for the amount of people that tend to overcam. If you notice anyone that knows how to spec a cam, you rarely ever see a 4 degree advance. There's just no reason for that much advance if you spec a cam with the proper valve events for your specific application. Think about it this way, advancing the cam just moves the powerband down. If you're spec'ing your own cam, you are already picking where you want your powerband to be through duration/lift (aka, the proper way). Now, there is reason to add a couple degrees of advance to get your IVC/EVO events tweaked, but that's about it.

Xtnct00WS6

iTrader: (8)

Thanks! So what does everyone think of the valve events of this cam: 230/234 .612 .598 110 + 2?

overlap of 12 degrees, intake centerline of 108, IVO of 7, IVC of 43, EVO of 49, EVC of 5, and Exhaust centerline of 112 (all at .050)

DCR of 8.66 and my static will be about 11.2:1

thehammer69

iTrader: (2)

advance it another degree.

Hammer

ArcticZ28

iTrader: (14)

That DCR could be trouble here in the summer even running 93. It gets pretty hot here lately. The tune is gonna have to be dead on.

Xtnct00WS6

iTrader: (8)

Are you saying that cause you'd rather see the ICL at 107 instead of 108? Or is it because of the valve events? The DCR also goes up with a +3. You don't think a 8.73 would be too high with the +3?

thehammer69

iTrader: (2)

I think that target DCR for 93 Octane should be 8.7ish. That is why I recommended the advance of +1. That being said...comp grinds on the large side, most likely your .006" duration will be 1-3 degrees larger. This will delay your .006" IVC event and thus, your real world DCR will actually be less since the DCR calculator is using text book numbers.

Hammer