I'm going to order a short block thru a local shop this week, Im looking at a 6.0 iron block .030 and a 4.1" stroke. the only thing I have not decided on is compression ratio. I have done a lot of research, talked to old school racers Etc. And am still having an issue deciding this.

Im will be running a comp cam, .622 lift, 258 int and 270 exh duration. I will also be running a pretty healthy nitrous shot. What are people running for comperssion ratios and nitrous? also on the larger nitrous shots, what timeing advance are you able to run?

 

what gas you want to run? get the .005 numbers for that cam and figure out your DCR. That will tell you what SCR you'd need to run for pump, for race gas, for whatever.

 

.005 is like 324 and 332 i think, im at work and dont have the cam card here, but its pretty stout. Im hoping for upper 400's on the motor. I am going to run RAce gas, so that is not a problem. I just dont want to be running too much sompression that I will have to retard the timing too much with the nitrous. I would rather make a little less on the motor and be able to get the full benefit of the nitrous

 

How are you getting a 412cid ? Im building a 418cid aluminum LS2 6.0, 4.30" bore & 4.100" crank and 6.125 rods ,are you useing shorter rods ?

 

Try this


http://www.c5frc.com/calculators/Com...Calculator.htm

 

I miss read the build sheet, they are using the 4" bore because it is a brand new block.

 

Ok So I founf a DCR calculator on the internet and entered my info and it comes out at 6.99, is that right? it says static CR is 11.54???

 

Dude that cam is huge. What are you goals for the motor? Power band? intake? Heads?
How much are you planning on spraying? 300? 400?

If you want to run race gas just for safety's sake then shoot for around a 9:1 DCR. with c16 or vp9 you could probably run 20 degrees of timing on a 300 shot. It all depends on your setup though.



Nate

 

That cam is close to mine Crane 650"/650"-255/260-112 +3 for my 418cid ill be running a pro fogger 250 shot with a low pressure fuel system with CAM-2 , and 93 oct. in the tank. Ill have 12.5.1 CR. to.

 

Yeah up your dcr with that cam 6.99 isnt much. You might need 12.5:1 scr etc.

 

Ok so I found my mistake in figureing the DCR. I put in 324, the exhaust adv duration, not 311 the intake adv duration. at that duration it comes to 7.44 DCR which is still very low. If I run it to 12.6 to one it shows a 8.27 DCR, is that about right? As far as the nitrous goes, I want to go with about a 300 shot if not a little more, depends on what kind of times I can get out of it. The engine builder is claiming with the Dart 225 heads, bbk intake and ported TB it should make 550+ at the crank on the motor, sound about right? I played around with it on Engine Analyzer and come up with about 560 - 580 around 7K RPM. At that RPM are shaft mount rockers, like Jessels, needed, or can I use a cheaper roller?

 

You can just send your stock rockers to Nasty nate and he'll hook you up for 250 bucks and they're rock solid.

If you could up your DCR to around 8.7 or so you could still run it on pump gas when driving around on the street. Hell just get a secondary fuel system and you can run c16 in the little tank...that's my plan. But definitely get that DCR up to 8.6 or 8.7 for the street. Maximizing DCR is the key to a well running motor.

Skip the BBK intake, get the Fast 90 setup and port match it.

 

Id love the fast 90, but I'm already dropping about 6K and cant afford it. Im getting the motor complete pan to intake tho, so I can not complain to much, 12 month warranty too...

 

With race fuel, you should be ok to 8.7:1+ dcr, but best to get some more opinions.
Run a cool engine (thermostat), good plugs, cai etc and nice tight quench.

 

Hey, while you're on here... do you have the title I've been trying to get from you for two months now??????? Or are you avoiding me????