JeepSpeed18 wrote:You are not helping me build this motor. lol I pick a build plan and then it changes and changes and changes. I will most likely run better gas. Instead of dishing the psitons we are just going to run a thinker head gasket. How much performance difference will I see with the cam you suggested?
Well I'll give it to you bluntly. Run the .043, yes the thicker .051 will drop you compression but also make your quench worse..so its a win/lose type deal!
The .043 may give slightly more compression, but because the tighter quench you won't have an issue..remember a tight quench fights of detenation!
Hence why I'm running a .038 quench height
Your staying with stock valve springs right?
And performance wise...do you like walking or running? Lol not really that type of comparison, but it comes down to what you want! The Comp 115 has a operating range from 800-4000rpm. It falls off quick at about 3800rpm. Its worse than the stock cam in the mid-upper rpms, but will make but loads of torque down low! Ever drove the older 4.2L? They are torquey little bastards, but fall on their face around 3800rpm lol, this cam will be similar to that. Theres the Comp 200 which is 1000-4200rpm..which I believe is probably your best choice. Can be run on stock springs, will be similar to the Comp 115 down low, but have more up top.
Theres the Comp 201, which is 1200-4400rpm..I like this cam, alot but I wish it had a bit more to offer down low. This is also the biggest cam reccomended for stock valve springs, out of the 3 Comp cams offered, I'd run the Comp200. Personally I'll be running the Comp 232, but its too big for stock springs..if you wanted to upgrade the springs, this would be the cam to choose!
And be serious with what you plan to do and stuff. Its the only way we can best help you..and like I said think now or forever wonder lol. 91 oct has no eythnol, so mileage gains will happen & you won't have to build the motor to such strict guidelines to run it on 87oct..it will just be a much better product in the end and cheaper to build:)
Heres what I've got for ya.
3.905 (.30 over)
3.500" stroke
58cc combustion chambers
.000 deck clearance (yous will vary here..I just set it at .000. So your final CR may be slightly higher or lower..not enough to worry though)
.043 head gasket
12cc dish (11.5, added the extra .5cc for the piston ring height- Kb Silvolite 2229)
Comp 200 cam
9.71:1 static
8.79:1 dynamic
It will run on premium just fine. Possibly mid grade pending your elevation & such. It will not run on low grade though! The higher compression will make a huge improvement over stock, it will be super responsive! Should get similar, if not slightly better mileage than stock, so long as you drive it accordingly & after its broken if of course! And will last just as long as a stock 4.0, should have better emissions also because the tight quench!
