Is 9.244 DCR to much for a non-daily driven street car. Pump gas??

 

Yes!!! Aim for 8.5 max on an efficient cylinder head and 93 PON. It just won't take more than that!!!!

 

Let me give more specs. 402, et245 72cc, .030 gasket, fast90/nw90, flat top 2cc valve relief and for those interested the cam specs are:

LSA: 113.5 CAM DEG
valve overlap: 35.8 CRANK DEG

INTAKE
valve open = 19.4 BTDC
centerline = 109.5 ATDC
valve close = 58.1 ABDC
duration = 257.5 CRANK DEG
lobe lift = .38059 IN.
valve lift = .647 IN.
lobe area = 33.12 IN * DEG

EXHAUST
valve open = 70.8 BBDC
centerline = 117.5 BTDC
valve close = 16.4 ATDC
duration = 267.3 CRANK DEG
lobe lift = .36634 IN.
valve lift = .62278 IN.
lobe area = 33.31 IN * DEG

May need to move, posted in wrong forum

 

whats the duration seat to seat? I believe you gave me the 0.050" numbers.

 

Dude, how are you planning on handling the acceleration of that camshaft, if in fact those are the seat to seat numbers!!!!

With a VE of 1.05, your Effective compression ratio is right around 8.85:1.
Which is a bit over what I would run on the street. Unless you get a blend of 104 GT Plus, then it would be ok. Or, you could do some mixing with E-85 to make it work. But I doubt you have that down there in the land of the Bush's!!!

 

How did you come up with 8.85? I come up with 9.479 with Pat Kelley's DCR calculator. Also comes up to 11.29:1 static.

 

You can't use duration at .050" numbers to calculate DCR, you need duration at .006". Your DCR is most likely going to be in the low 8s. Give us the .006" duration numbers.

 

So, what are all the specs that are needed to figure this out and how do you figure it out?

 

actually, you are right, I had the wrong gasket and ring land volume entered. With your setup and the said 1.05 VE, I get a 9.47 ECR.
I am coming up with a static of 10.76:1

I have setup my own calculator in excel, it took me about 3 months worth of staring at this screen everynight to make it, but I did it myself!!!

 

Patrick,
If you are correct, I should have no problem with pump gas then, right? I'm trying to get the other specs (.006) to be sure.

 

please read previous!!! No, I don't think you will be safe with those numbers. You need to add 8cc's of combustion chamber volume somewhere. I would prefer to do it with the head or the piston.

Or, you could get a cam that has a seat to seat of around 280 or more.
Or you could advance your intake lobe to 120, but that would be rediculous.

 

Using Comp LSK lobes as an example, add 50 degrees to the .050" number to get the .006" number. That said, I come up with the following:

11.41 SCR
7.70:1 DCR

Hope you have faster ramps than 50, because otherwise your motor is going to be a pooch!

 

what are you using to come up with that?

 

I used the DCR spreadsheet calculator that is stickied in the Advanced Tech section.

I also used the following (to get me in the ballpark)

Hydraulic lobes:
.006", .050"
307 257.5 intake
317 267.3 exhaust
113.5LSA, 109.5 intake centerline (+4)

Unless you're running a much faster solid roller grind, your DCR is going to be very low with a cam this big. If in fact, you're running a solid roller, the faster seat timing should get your DCR into the 8s, but not high 8s. Again, this looks like a case of too big of a cam or too little static compression (to produce good area under the curve).

Why such a huge cam with so little static compression? What are your goals? With a 58 degree IVC, you're going to have to spin your motor into the 7000+ rpm range to make good power. Hopefully, you're not planning on running a FAST intake to do it.

 

This is a hydraulic roller. How accurate is the spreadsheet. The calculator I have been using keeps coming up with 9.4790 DCR and 11.287 SCR. This is not installed yet and to figure this out. Thanks for the input. It is a Cam Motion grind. Still trying to get more specs on it. I want 500rwhp NA with A4 12bolt.

 

GREAT INFO! Thank YOU.

so for a ms3 setup how can we get that DCR up..

CAM only, stock LS6 heads.

I want to be OPTIMIZED cam only package with MS3.

 

Hate to burst your bubble, but you have virtually no chance of getting anywhere close to 500 rwhp with an automatic and that mis-matched of a combo. Static compression is too low, dynamic compression is too low, intake manifold is too small, and heads are too big for the intake. Who talked you into that cam anyway?

 

Ok, I am going to give my little cam installation secret away, so listen up. This has been backed up by dyno data.
I don't know what the specs of this cam are, but the simplest way to install a cam for max overall power is to take the LSA - ((exhaust duration - intake duration) / 2 ) = Intake Valve Centerline install angle. This number will give you the best overall power for your cam as long as you have a good exhaust and intake system.

So, if you don't believe me, just start asking people questions about where they have installed the intake lobe and I bet you will be within a degree of the best overall power.

This is not for peak numbers, but for a best overall power number. If you want a little more down low, close the intake valve sooner, but do so with a different cam.

Little more power up top, give it some more lift, with a different cam.

 

It's still in the building stages luckily. As far as the cam goes it's not in stone either. Are you "in the know" on this sort of stuff or just speculating. If you do know, what is your suggestion? I will be spraying also.

 

I'm not just pulling numbers out of the air, there's a lot of science to choosing the right cam. You'll have to answer a bunch of questions to choose a cam that makes the most power under the curve.

Street, Street/strip, hot street/strip, or strip-only?
Transmission?
Gear?
Converter/Clutch?
Tires/suspension?
Fuel of choice?
Displacement?
Static compression?
Maximum rpm?
Intake manifold?
Head flow?
Exhaust?
Power adder?
Driveability importance?
Fuel economy?
Vehicle weight?
Tuning software? Speed density or MAF?
Desired power level?

I'm sure I've left out other important questions, but if you can answer all of these questions honestly, then you'll have a much better cam chosen that meets your needs.