I'm looking at a 383 shortblock that has 11:1 compression with the Trickflow heads with the 62cc combustion chamber, so there is really no option of getting it any lower. Can I still run 93 octane and drive it on the street?

 

Depends on your cam which determines the DCR.
Why do you want it lower?

 

I have a LT4 Hot Cam. I want to be able to run the car everyday on 93 octane with no problems, do you think it would be okay? Whats the highest you can run on 93 octane?

 

Figure your DCR and see. If it's below 9.0 you are OK. If its below 8.5 ya are leaving HP on the table.

 

Probably be close with the Hotcam.

 

I'm running 12:1 compression with a DCR at about 9 on 93 pump gas. You need a good tight quench and every thing works out real nice on reverse cooled heads.

Steve

 

WOW, I would love to see your engine specs! Nice 1/8th times!

 

Actually I'm simply running a 355 with a forged crank and flat top pistons. Quench is .041" and CR is 12:1. Chambers are 53 to 54 ish. Cam is a hydraulic roller.

I kinda think my 1/8 mile times are a bit off where thay should be. The car will mile-an-hour pretty well (93 MPH) but doesn't 60' very well at all at 1.7X 60' times. This kinda goes with the territory on a stick car but I've seen other stick 4th gens do way beter 60' times. It's still a work in progress.

Thanks

Steve

 

Not to jack the thread but, What heads are you using?

 

Thanks for the replies everyone, but how do you figure out the DCR?

 

Do a search for a DCR calculator on line and enter the info.That,s dynamic compression calculator and ya have to find one that uses the advertised spects of your cam not @50.

 

I'm using LT1 heads (worked of course) and an LT1 intake manifold. I don't know if you can safely mill or angle mill AFR's or TFS heads clear down to 53 CC's. If I was building a motor from scratch I'd probably zero deck the block and go with a .039 gasket and then size the chambers to yield 12:1.

I use a DCR calculator that I found on the net. Its a little app that was written by Patrick Kelly. Works very good. I can't tell you how many "what if" games I played with different cam grinds. These exercises kind of begin to give you a better feel for how duration and Lobe Centerline angle affect DCR.

Steve

 

Yeah only way to get small chambers on these LT heads is with a LT1 or LT4 casting, a AFR or TFS will leave a ton on the table in those heads if you want the chambers that small, if you can even get them there. Lowest I've had them with a good port job is 58cc. You could mill the snot out of the stock AFR port job with small chambers and get them lower but I'm not a huge fan of the AFR port job with small chambers.

Bret