mr2guru

iTrader: (16)

Will this work well on 93/94 pump gas N/A application? Anybody running similar DCRs with 21* of overlap? I'm looking to get to the ragged edge of pump without having to compromise too much timing up top.

http://img.photobucket.com/albums/v2...ru/dcrcalc.jpg

brad8266

iTrader: (23)

You will be having major PTV issues with that setup. Gas will be the least of your concerns. Hello Mr Piston, meet Ms. valve.

8.7 works on 93 with a good tune.

Patrick G

iTrader: (14)

Your quench is tight. Your DCR is not too high. Run a cool thermostat and keep an eye on your timing at lower rpm. You should be good to go. Once you get past peak torque, you'll probably be able to crank the timing up towards 30 degrees (if that's what your motor likes). This cam of yours will make some BIG top end power!

mr2guru

iTrader: (16)

I've already addressed that with -3cc reliefs in the pistons. This is a built 347.

Patrick,
That's what I am shooting for. If it makes peak at ~6800 that will be perfect for 135 traps with this 4.10 rear.

Patrick G

iTrader: (14)

It will probably make peak power around 6400, but carry nicely to 7000...ideal for a 135 trap speed.

brad8266

iTrader: (23)

That huge cam with 21 overlap and 57cc chambers clears even with 3cc relief?? I have 2cc and a smaller cam and i dont think i can fit 57cc chambers.

mr2guru

iTrader: (16)

Welded chambers.

brad8266

iTrader: (23)

What the hell is that, i wanna know now!!! Ive seen em but dont know what exactly it does.

mr2guru

iTrader: (16)

It's where you fill in part of a 64cc or 72cc chamber with al weld, heat treat, then cnc out the shape to the desired cc. This allows for much smaller chambers without dealing with the problems associated with a lot of milling.

brad8266

iTrader: (23)

oh ok, thats cool, im gonna go get my mig right now, lol.

1baddls1

iTrader: (31)

would def want to TIG weld them - and be DAMN CONFIDENT in your welding capabilities

brad8266

iTrader: (23)

I was kidding, i would never use a mig on a head.

RAACCR

I'm not sure I trust that DCR Calculator. It says I've got 8.97:1 dynamic (and 11.36:1 static). I'm running 93 octane, 28* of timing, and I went as lean as 15.1:1 in a few cells down in the lower right corner while dialing in the speed density tune, with never more than 2.1* of knock retard.

brad8266

iTrader: (23)

Whats that have to do with the DCR calculator?

RAACCR

Plug the specs of a stock LS1 into that calculator and it will tell you you've got 10.3:1 static...I think the numbers it gives you are too high. (I think my actual compression numbers are about 3/10 lower than what that calculator is telling me.)

yak

iTrader: (15)

i'm at about 11.6 scr and 8.7 dcr and I'm planning on running 93 in mine, it hasen;t been tuned yet, but it starts and idels on my old cam only tune from a shitty 10.2 scr.

pianoprodigy

iTrader: (1)

The numbers are correct. Use another calculator with stock LS1 stats and you'll get the same numbers.

RAACCR

It is a nice calculator...I just had my doubts about the numbers it gives. If it is in fact correct, then we may want to re-evaluate the DCR limits that we find acceptable for pump gas. (Current consensus on the board seems to regard the acceptable/desirable pump gas DCR target range around 8.50 - 8.75.) This calc says I've got 11.36:1 static and 8.97:1 dynamic. And, I went very lean in a few cells during tuning with very little knock. During tuning, my worst AFR went to 15.1 with 28* commanded timing, and it only pulled 2.1* knock retard. That being the case, a well tuned motor should be able to tolerate more than 9:1 DCR...maybe alot more?

koolrayz

iTrader: (26)

Not to hijack the thread I think my question apply's when does the size of the cam, overlap and alike influence the DCR to octain formula? My new cam has 246/254 @.050 with .648/.646 lift. my SCR is 11.75 my DCR will be 8.6 surely I will be alot closer to the ragged edge of detonation on pump gas than a milder setup with the same DCR. thats assuming I wont be in trouble I may have to pull alot of timing on my street tune.

pianoprodigy

iTrader: (1)

Of course, the target DCR for a particular octane rating is only a general guide. Elevation, temperature and other variables will obviously also play a factor in knock. Stating that the calculator is inaccurate merely because your combo that comes out to 9:1 DCR doesn't knock much is flawed logic.

Just to be clear, I didn't do any of the calculations in this calculator. J-Rod did the calculations. I merely cleaned it up and made it user-friendly. However, I have compared the results of my calculator with others available online and have come up with the same results.