Hey is there a compression calculator online for 4cylinder's that any of you senior guys would recommend using. Getting ready to turbo my single cam and have a cosmetic .075" thick Hd gasket wanted to look into what the compression would be sitting @ before i put it on, maybe get thier thicker .120". i'll search via google see what i can find for calculators, any help on good recommended site would be greatly appercaited for now and future use.

 

# of cyl dont matter on comp ratio. there is 100's of sites for comp calc. i just do it myslef cuz its really ez. yall need to know bore, stroke, vol of head gasket, comb chamb vol and how far below the deck the piston is and if the piston is dish or dome or valve relefs for that volume. it's really purty ez. but i woulnt run such a thick head gasket the thiker the the gsket the more chance it'll blow out

 

I found one that worked good for me, i've heard that thicker Hd gaskets can blow out, haven't seen too many people complain though...i did look into combinations w/ thicker head gaskets. i have a .075" might exchange it for lesser thickness one.

With the neons BxS, 48cc sohc head and a 0.075" hd gasket comp came out to:
8.379 compression ratio

with same specs but with 0.060" hd gasket comp came out to:
8.714 compression ratio

also with same specs with a 0.051" hd gasket comp came out to:
8.929 compression ratio


I belive i might exchange my hd gasket unopened/unused for either .060" or 0.051"....i think 1st ratio is lil too low and others would be what most say is ideal? Any one elses thoughts on best ratio out of these 3 feel free to throw in advice. pistons that are out there 4 the 2.0's are around 8.8:1, Might be best for the 8.7:1 ratio. For more info on the project i'm going to be running a 16G-Large TDO5HR 9.8T believe it was a Evo 8 turbo, saw that its flow rate @ 14psi was 505cfm, and max output was 365-385hp @ 22 psi.... Already have most everything fab'd for the build, only really looking to push between 8-10psi....Any thoughts guys please feel free to comment...

 

i aint to turbo guy but i was told that comp ratio needs to be allot lower on turbo like 7-8:1 range with that much boost. are yall really going to turbo a non turbo motor? if yall is id be running eagle rods and not them powder rods then while i was inthere id get forged turbo pistons cuz cast and hypertechtic pistons fail fast when you get any lean condition to cause detonation

 

Yea very true, well i found out later last night the thicker head gaskets are only for the dohc neon engines and not the sohc engines...moral of the story i'm going to go ahead order piston and rods. Theres many guys that i know that have run 8-10psi on stock block, they also dont rip on the car all the time, i'll go the extra effort and do the piston and rods. I know if you go to low in compression it'll create alot of turbo lag. thanks 4 the insite looks like i'll have to go the more expensive route to make it right, the factory compression 9.8:1 is too high to boost 4 me.

 

y not get a dohc head cuz with adjust cam sprokets yall can realy dial in the power

 

yea thats what i orignally had on it, comp was like 9.3:1, i had bought the car like that, cam caps wouldnt tighten they were all messed up i know you get more power out of them, was going to put one back on, i just like the more simple set-up of the sohc head, my sohc head has full pnp job, cam , and adj cam gear, i found some pistons n all on neons.org, so i'm going to go with them, but if i had everything i needed to go back to dohc topend i might but i just think those dual cam heads flow good but the set-up is straight junk. between the floating rockers and crappy structure of the head...dont care to mess with them anymore...lol, i have a r/t w/ dohc engine and nothing but problems since i bought it. wife has sohc 2dr shes never really had any real problems.

 

idk about floting valves cuz i race w. guys running dohc neons turning 7500+. the desine of the dohc vavle train aint no diff than the old 2.2 and to keep them from floaing is all in the springs. i used a stif spring and at 8k the dont float the valves. find a good engine shop and they can make valve float never happen