buguy wrote: ↑Fri Oct 05, 2018 3:04 am
Yeah I'm planning to get my Panchitos with 68cc chambers so I don't have to go too crazy with the deck to get my compression where I want it.
I plugged your numbers into the engine calculator and I come up with 9.0:1 compression if you use the CNC 61cc panchitos with a 82X94 and .050 deck.
Why would you want to have to hog out the chambers to 68cc's??
If you use a Webcam 86B or similar with a little duration you will be just about perfect.
Don't make your engine a dog off boost with 7.5:1 compression.
I figured 9:1 would leave me little room for boost. Nothing but pump gas here.
I guess I also figured with 2275cc's it would have plenty of grunt off boost, even with low compression.
I just ran the numbers and at .050 deck with 61cc heads it is 9.2:1, surely that's too high for a turbo street car?
Also remember I live in Florida, it's really hot here like 10 months a year.
Youd be surprised what a little boost timing retard will do for ya. I'd rather have less psi and more overall power than higher boost levels and a dog off boost. Get below the proper operating range of the cam and you'll have a dog that you have to advance the poop out of it and probably run hot.
That's kind of why I was considering the 86a cam. It's operating range Is 1500-6000 rpms.
But again. This is all just reading and basically guess work. This is all pretty new to me.
The only reason I am going slightly lower on the c/r on my engine is to have a little more wiggle room with all the Chinese parts for the "just in case" something was to come loose. I was going to run it at a .036 deck to get 8.6-1 but figured I'll bump it to .042 for that extra bit of piece of mind. I believe if I remember correctly the 86a wants 8.5-9.2 c/r
CB has an engine calculator online plug in your numbers and it does the math for ya. I lucked out when I went from a 78mm crank to a 80mm it gave me a positive deck with the 5.4 rods so I just had to add shims
I'm sure it does I'm not to that level of expertise yet.lol I personally get the static c/r set then get the boost to a comfortable level(or till it pings then bring it down a few degrees) and enjoy. Your not running a 10-1 c/r so you will still see a decent amount of boost before detonation sets in. Meth injection or intercooling will help if you want higher boost, then again a properly tuned efi system with crank fired ignition will bring it to it's full potential it all comes down to how much time and money you want to throw at it. Keep the build fun and enjoy the hell out of it:)
Time to start looking at dynamic compression ratios rather than static, a stock 1600 with stock cam has very little valve overlap (both valves open) therefore generates cylinder pressure at lower rpm but peaks earlier. Now take the same engine and put in a w110 cam it will have more overlap, will bleed off compression at idle but produce more power higher up, that's why you can push the static compression up when using a bigger cam. Typically pump gas can run up to 7.5:1 dynamic compression on a NA engine, because you are turbo with a programmable boost retard then.....
Punch my numbers in...7.8:1, 24 lbs boost, 110 ft altitude.
It's all a matter of fuel, ignition and IAT management. Spend some money on the right parts and you too will have a nice combo.
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.
buguy wrote: ↑Fri Oct 05, 2018 3:04 am
Yeah I'm planning to get my Panchitos with 68cc chambers so I don't have to go too crazy with the deck to get my compression where I want it.
I plugged your numbers into the engine calculator and I come up with 9.0:1 compression if you use the CNC 61cc panchitos with a 82X94 and .050 deck.
Why would you want to have to hog out the chambers to 68cc's??
If you use a Webcam 86B or similar with a little duration you will be just about perfect.
Don't make your engine a dog off boost with 7.5:1 compression.
9:1 and 86b would be a very nice combo. It would drive great, have nice quiet valvetrain, and be really angry when the boost is up and the pedal down. Even at 68cc though, and the same deck, you are at 8.4. Thats fine too. Very unshrouded valves I'd bet. CB will cnc up to 68 now Clone. I think thats a recent addition.
Also do you think that the 86b with 575 lift and 260 duration and says it's a 3000-7000 rpm cam would be better than the 86a with 505 lift and 252 duration and 1500-6000 rpm range?
