Ok I ran le2 heads with a le1 cam and spun my rod bearings and my main b. I am now going with a 383 stroker kit. dragonslayor crank compstar h beam rods, and -18cc diamond forged pistons. What is a good cam to go with. I want my car to work at its best potenial. I have 40lbs injectors 58mm thb, trex fuel pump, kooks long tube headers. and I also want to run a 150shot at it. What compression ratio should I go with. I need help.

 

I went through the same decision recently. I'm no expert on this, but I did learn a bit.

For my 383, LE2 heads & Mahle flattops, Bret's recommended cam was LE3. Those pistons put me around 12.5:1 SCR, but DCR should be OK with cam. BUT I haven't finished it yet.

You should look into flattops unless planning to boost or run a really small cam, I think. With -18cc pistons your CR and DCR will probably be too low. Play with the DCR calculator on this site and potential cams. Search DCR The general recommendation for LT1 with premium seems to be 8.5 to 9.0 range = best DCR.

 

ok I ran that by my engine builder and he said that motor aint going to last long with that high of a compression. I have a set of flat tops, but I am torn. my engine builder says hell no and loyd and bret say another. I allready blew my **** up once. I dont want to do it again. Why cant I find a safe comp ratio and use the -18cc piston. Not use the le3 cam, and just go withe the gm 847 or somthing else. I am worried with that High of a comp. This is driving me crazy. Is there no other option. Nothing else will make good power, no one else knows a good set up. I uderstand about the dcr, but 12.5.1 holy **** man.

 

If your engine builder is afraid to build a motor that has some compression, you need to talk to someone else. Don't ya think?

 

With an undecked block and those -18cc dished pistons your compression ratio will be in the high 9s to low low 10s. I would try to find a piston with a little less volume in the dish.

The cam will really depend upon how you want this thing to drive around, if you can handle a tempermental car than go big for your combo, if you want something thats easy on the driver then get less overlap, but the amount that can be handle is again determined by the compression ratio.

 

I used the -18cc pistons in my previous 383, with an undecked block, it ran fine, and with some tuning I ran 87 octane around town, switched tunes and ran 91 at the drag strip. the 847 and 9.8:1 compression made for a tempermental low speed car. I tuned and tuned on it and it still needed a little warming on cold days, and its idle no matter what I did was very gassy.

With my new motor I went to a -12cc dish piston, zero decked block and the .039 fel pro gasket. It requires 91 all the time, but the lower responce of the car (with basicly the same cam) is ten fold !!!, I plan on getting some track time in after the motor is bug free and 1500 miles on the clock.

 

I feel your pain. I was really concerned about the high CR myself. Still am, honestly. But I figured that's what I'm paying the smart guys to decide for me. So, I swallowed hard, trusted Bret, and started writing big checks for Compstar forged rotating parts to build the bottom end right. I threw in 4-bolt splayed, too, for good luck. I've been told that's overkill and can hold 1000 hp. Dunno, myself. I have seen other 12.5 motors discussed that work fine with the right cam. I would never pay a builder to put something together that he said will blow up, either. I finally talked mine over with Eric at VRE - he is highly regarded and has built similar motors. He didn't have a problem with it, either, so I bought my stuff from him.

Since you already wasted a motor I can see being a little more conservative this time. But WS Sick suggested a good compromise - at least consider less dish, and definately talk to other builders. And if you can, get the block decked to improve squish for better detonation resistance. I'm going with 0.038. If you like the 847, see what CR that cam needs for good DCR.

Tell us more about what you blew up before? High CR on stout bottom end?

 

Has anybody calculated your dcr yet? A lot of talk about the 12.X:1 scr, but really, big deal. Find out what the DCR is doing and go from there.

 

Here is one of the DCR calculators:
http://www.rbracing-rsr.com/comprAdvHD.htm

However, this one uses IVC at 0.050 but Bret (sstrokerace) and 1racerdude have both emphatically said 'do not use IVC at 050 to calculate DCR!' They really understand this stuff, and I am merely parroting what I have tried to learn from them. Search DCR and 1racerdude or sstrokerace and you will learn a lot! A few hours of searching and reading will be worth it.

I guess it's best to find a calculator that does not use .050 specs. I'm sure there is a link in prior posts, I just couldn't find it quickly.

Edit: this one is better:
http://www.empirenet.com/pkelley2/DynamicCR.html You need to download it. It does not use .050 numbers.

Here's a small start on related threads:
http://web.camaross.com/forums/showt...dcr+1racerdude
http://web.camaross.com/forums/showthread.php?t=351113
http://web.camaross.com/forums/showt...dcr+1racerdude

Hope you find them helpful.