dj haf

im having my engine rebuilt now because i lost compression in all the cylinders... anyways, i was thinking that since the engine's out, i should stick in a cam just to shave a few tenths off my time. i dont want to go all out on a cam since i'll be doing that later when i swap out the tpi for a mini ram, so right now im just looking for a cam that i can stick in without having to replace anything major... anyone got any ideas? i want the most hp i can get by just the cam... i dont wanna have to buy lifters or anything else... thanks guys

cz350Z

I'd spend the extra $ and bump the compression a lil while everything is apart. Then pic a cam to compliment everything. Even if you go a little bigger on the cam now your motor will shine when you go with the other intake setup. Always keep later in mind. I learned that the hard way.

dj haf

what should i do to bump up compression? im going to have my heads ported but i dunno what that would do for my compression... anyone know how much i should have it ported to for good compression?

hydric

well

what kind of heads u have on now along with the combustion chamber size? what type of piston comp. ratio do u have along with that type of pistion? flat-tops or domed? these are some things to take into suggestion when trying to do some math for compression

dj haf

everything is stock

hydric

well then i would wait over the winter until you have enough money to upgrade other parts...then treat her to a nice cam

dj haf

instead of getting a cam you think i sould get my heads ported for now?

hydric

get a set of nice heads, new pistons (i wouldn't get domed) but beware of your compression ratios... you dont want to have to run $7.00 /gallon race fuel cause pump octane isnt enough...

but no use to replace your cam when u have intentions of building.. sure a different cam with a stock set-up would help a lil, but dont waste the $ on it cause with your new set-up (your mini ram and perhaps a set of nice heads and new pistons) you wont want to use the cam u would buy now... no use in buying 2 cams with two differetn set-ups =]

summit flat tappets are only $80 bucks (including new lifters) but $80 bucks is 80 bucks...


your rear end stock as well? what type of tranny do u have?

the bigger the cam, the more higher the rpms have to be to produce speed, the smaller the cam, the lower the rpm to produce speed but it will max out...

do some research but i would wait to put a cam into it until you get some other goodies to save yourself from doing a task twice.

hydric

oh and of course that would just be my route....

but to give you an idea.. i have a set of 1.94's and my cam is a shade above stock specs... and the cam that it orig... had (keep in mind it was in a corvette, so the cam duration was longer and such) and it ran good, smaller cam, same set-up, it runs realllllllllly good..

bigger cams dont mean better performance...

take in mind, if i had a 3.73 rear end and a better built 700r4 with a nice stall, my cam would for sure be bigger...

i would get them heads ported real good, get that ram on there n some nice pistons to accomadate your heads then worry about what cam u need to get if one at all...

dj haf

here's the idea. wanted to get some work done to the engine before she got put back in the iroc... but if anything i'll just have my heads ported to the max for now. then ill get myself headers and then the mini ram... then the cam. i have a 700r4 and 3.23 gears in the rear... what kind of pistons should i use to raise compression on my L98... might as well tell my mechanic what to put in it before he does it... i want to get something more out of my car if i can while it's being rebuilt - but i dont have enough money for a stroker so im just stuck with either getting a cam, porting out my heads, or maybe LT headers... what would you suggest?

hydric

forged flat tops.... especially forged if u plan on running NOS anytime in the future.

each compression ratio gain will gain you in the torque category..

taking into consideration and nice exahust, nice heads, head gasket thickness, etc, the highest compression you'll want to run (unless you plan on burning race fuel) is about 10:1 10.5:1 on 92-93 octane (pump gas)

you'll need nice aluminum heads to really worry about getting to high of a compression ratio and personally i wouldn't use alum.. heads cause i am a fan of cast iron...

hope that helps

dj haf

if you were me... and you're having your engine rebuilt, what would you tell your mechanic to do to raise the compression to around 10:1 or 10:5:1? how much gain do you think i'd see by raising the compression? and how much should i port the combustion chamber to on my heads for a good cr? im going to keep my stock iron heads unless i can find cheap aluminum vette heads that my friend can port out for me.

so far i know to tell him to get me forged flat head pistons, thick headgaskets (how thick, btw?) and some head porting. the smaller the combustion chaimber, the higher the cr right? thanks for all your help man i really appriciate it !

hydric

port the heads, around those ratio in the piston selection (and yes flat top pistons, some people really liked domed, i dont know but u can seaarch on your own for that)

the engine works but taking air, "compressing" n mixxing ti with fuel, then the spark plug ignites the mixture...lower compression WILL result in less power and higher emissions... so yeah u should see a gain by having a higher compression ratio.

i wouldnt go above 70 cc, i would stay around 64cc. you should ask this question to someone else who more familiar with heads cause i dont think i'm qualified enought o give u full advice u should take to the bank on that, sorry!

I would go with stock which i believe the fel-pro (the brand people usually use for rebuilds) is .039 compressed. ask your machine shop what he would suggest for head gaskets to match your heads n set-up... overall, your deck level on your block will be the factor on what size head gasket to use... zero deck or not, i personally wouldnt go below .02x thickness (compressed) due to leakage. its all about getting the proper quench by decking the block and using the head gasket to accomadte the deck... therefore your machine shop mechanic will furthur you in a better answer cause i can't help u there. that is something that relies on the shape of your engine block...

generically speaking...

when dealing with compression, there are many factors (as u can see) that will effect building something...

really, cam timing, how hot the intake is, so many factors could effect compression...

do a search to find out more in-depth as i generalized thigns to save typing...