multi port fuel injected 363 c.i. sbc cam help!

[bytor]

Good discussion,
For my planed build. Using the calculator and keeping everything the same except the head CC’s in order to decide on the correct head CC size. I get a DCR of 8.59 for the 65cc and 7.87 for the 72cc head. A DCR of 8.0 – 8.5 seems to be considered the safe max. So, the safer choice for me is the 72cc head with the 7.87 DCR for the street and pump gas, correct?

 

[grumpyvette]

"the safer choice for me is the 72cc head with the 7.87 DCR for the street and pump gas, correct?"

yes your correct ,you seem to get the idea!

 

[underpressure]

Hey guys; Sorry, I had to put the build on the back burner for a minute, had to go rescue a daughter 2500 miles that-a-way, just got back home....good to be back!
Thanks again guys; I can see the breakdown indycars provided and the idle and drive ability aspects gained or lossed by the cam profiles. Yupp!...just in the two weeks i've been on the road fuel prices here in ca have climbed about .50, so i'm still looking at "reeling" this baby in a little bit....tragic!

 

[Indycars]

Hey guys; Sorry, I had to put the build on the back burner for a minute, had to go rescue a daughter 2500 miles that-a-way, just got back home....good to be back!
Thanks again guys; I can see the breakdown indycars provided and the idle and drive ability aspects gained or lossed by the cam profiles. Yupp!...just in the two weeks i've been on the road fuel prices here in ca have climbed about .50, so i'm still looking at "reeling" this baby in a little bit....tragic!

Hope it wasn't anything too serious!

In your first post you said it was to be a weekend driver, has that changed? How many miles do you think it will be driver per year ?

I hate to see you go backwards, so I prepared this table......will you really save enough to make a difference ???

 

[underpressure]

Hi guy's, Rick..thank's for asking....
No nothing too serious, just your standard he's an @$$hole daddy, come rescue me 2500 miles that-a-way & 2500 miles back ride!
Yes...the intended use for this has changed a bit, I'm looking more at using it for some road trip's than a weekend warrior, but still looking to make good power and get some kind of mileage!
So anyway, I was crunching DCR numbers using online calculators and was surprised with what I discovered.
Now before I begin, I did pull one of the heads off just to double check my clearances, The head gasket I'm using is the Felpro 1003 the i.d. is 4.166, the thickness is .041.
I do have .003 on the deck, SCR comes in at 10.33, .044 Quench.
So this is what I discovered using these online calculators with the same original Isky cam.
Pat Kelley_______________7.68244 DCR
projectpontiac.com_______7.7 DCR
KB Silvolite United Eng.____8.194 DCR
Wallace Racing __________9.04 DCR
RB Racing RSR Advanced __9.28 DCR
Is it anybody's guess....or is one of these accurate?
I think i've scratched "all" the hair off my head......
It seem's there should be some kind of simple science to this!
I did a little research and the concensus is that Pat Kelley has the most accurate DCR calculator....
It also seems to be agreed that a DCR no higher than 8.5 with aluminum heads, EFI, coated flat top pistons, and a tighter quench area (somewhere between .030 and .050) creates a higher efficient burn that tends to counter pre-ignition with the use of pump gas.
Has anybody else run into this problem with such broad variances in calculating DCR with a single cam profile?
So many calculators....So little camshaft!
Thanks again....underpressure

 

[Indycars]

Sorry I didn't respond much earlier, somehow I didn't see the questions the first time I read your response.

I tried all the above calculators except for the Pat Kelly since you have to install software for that one. Using identical numbers in each calculator I got these results.

projectpontiac.com_______7.73 DCR
KB Silvolite United Eng.____7.72 DCR
Wallace Racing __________7.68 DCR
RB Racing RSR Advanced __7.68 ??? DCR ( It says to use IVC @ 0.050" and we don't know what assumption they are making for the actual IVC, but when I use 73, I get 7.68 )
Not sure I would use this DCR calculator for our purposes.



Not sure what went wrong, but it looks like with the Isky using a IVC angle of 73 degrees, you should NOT have any problems with detonation using a DCR in the 7.7 range.

Even if you use the Crower 00471 (it has the earliest IVC of those talked about), your DCR is 8.0. Still an acceptable number.

[IVC = Intake Valve Closing]

 

[busterrm]

I use the Pat Kelley calculator and it agrees with the calculator you set up Rick. Actually I use them both and are within a 10/100s of each other.

 

[Indycars]

I use the Pat Kelley calculator and it agrees with the calculator you set up Rick. Actually I use them both and are within a 10/100s of each other.

Thanks for the feedback, it's good to see that we all agree. Past 0.1 point on a SCR or DCR is pretty much meaningless.

I suspect my number would be lower than Pat Kelly's by 10/100s you speak of. My calculator takes in account some very small spaces around the top ring land, which would lower DCR very slightly. The difference would also depend on how many decimal places where you round off the number.

Excel stores numbers accurate to approximately 15 decimal places. You may have only two decimal places displayed on the worksheet, but the underlying value has the full 15 decimal places.