I've done all the math until I'm blue in the face and I come up with a DCR of around 9.1 to 9.3 (SCR 10.8-11.1) and since I'm having to use a thicker gasket (0.062) since the block had to be milled my quench is now 0.060. I know this obviously isn't the ideal set up, but will I see any considerable negative effects of this on the street? I'm sure the tune is where it's at, but will it be a simple pull of a few degrees timing or more involved than that?

Thanks,
Anthony

 

Are you running a LE1 cam? -5cc flat tops and LE1 heads? How far down in the bore is the piston so I know the deck height....

It's probably not that high of a DCR.

Bret



EDIT: IF YOU HAVE A LE1 PACKAGE ON A 355 with 11.1 compression and use a Fel Pro Head gasket you are still only at 8.5:1 DCR which is fine.

Bret

 

Yes, it is the LE1 cam with Ross Pistons (-4cc eyebrows) and LE2 heads (55cc). The pistons are approx. .008 in the hole. I got a hold of 1racerdude and he said that I need to get him the advertised duration so he can figure it out. It figures that is the only thing I don't know about the cam, lol. The machinist said he decked the block approx. 0.014-0.015 to make the sides even and level with each other.

Thanks,
Anthony

 

I have all the specs on that cam since I designed it so let me give you some exact numbers on it.

With that setup and a FelPro head gasket you are at 11.5:1, and the DCR is 8.8:1

If you play with the ignition curve you should be ok, I would run a 160deg thermostat and if you are in the south maybe look at Evans NPG+ so you don't have to dial any timing back.

Bret

 

Thanks for the info. I really appreciate your help and hopefully after this weekend I will be able to let you guys know how everything went. Thanks a lot!!

 

can you post the formula for finding the DCR or a calculator I would like to know what mine is also. here is my info 355 with MSM ported L98 with 170cc intake runners avg airflow of 217 and peak of 257cfm from .500 to .600 60cc chambers pistons are .003 down bore wiesco with 5.4 cc of valve relief. supervictor intake and custom cam with 256-268 @ .050 on a 112 lsa .565 .585 lift need anything else?

 

Tony,

I use the program you can download off this web page. Pretty nice tool.

http://members.uia.net/pkelley2/DynamicCR.html

Michael

 

What people are doing wrong is using the IVC at .050 when you need to have the actual closing number to get the DCR. That's basically it.

Sheppard, you don't have to be concerned with the DCR since you have a 256 @ .050 duration cam and a static compression around 10:1, depending on the Intake Centerline you are going to have a relatively low DCR, nowhere near standard limit of 9:1

Bret

 

hell, i always thought joe o was doing his cams. or maybe i was thinking about phil's...i guess thats what i get for thinking!

 

He was doing them. Lloyd is a great guy to work with. The DCR on a stock bottom motor with a LE1 package is 8.3:1

Bret

 

Didn't have the adv spect so I wasn't going to guess. To many things can go wrong.
I figured the cam was around 250-260 adv but didn't know for sure and it is better I stay out of any mess up on the figures.

 

Advertised is over 260 but the actual closing is going to give the real DCR. Unless you have the righ lobe profile it's hard to tell anyways.

Bret

 

I have a way to figure the closing from the adv along with the @50,that's pretty close..

 

ulakovic22,

If your pistons are .008 in the hole, why do you want to run such a thick (.062) head gasket?

Why be so concerned about DCR and not address the bad quench height (.070") ?


Doug

 

So a Dynamic of 8.96 should be fine? Static is 12.19