okay is this a joke 12.5 com.

[dsm_4g63]

JE 12.5 Compression 2.0 Pistons (set of 4) - JE125

okay i was looking at a higher compression pistons and came across these i didn't know if that was atcually a piston that clamed that it as a 12.5 compresson. so the point of this post is; is this a resonable for a 420a.

 

[Black95awd]

for an NA car this is fine. more compression = more power. I have seen 13.5:1 NA 4G63's.

 

[dsm_4g63]

so would you know what else might be done to the motor or could i just get the bottom end kit with the ealge rods main bearing and the 12.5 je pistons..ect.

i know nothing about the 420a motors but i am familair with the 4g63 but, i know that the 420a can't hold up to the same stresses on the stock internals as the 4g63 can. but i just got a 95 eclipse for free that runs so what ever i put into the car its a gain from were its at now. but i'm only looking to tune it up above stock and then sell it for a 1g gst or tsi or rs-t. any advice on good mods with the 12.5 compression pistons?

 

[Defiant]

I don't know if you'll be able to get good enough gas to run that high a CR anymore.

 

[bmoha2]

probably have to run 105 octane leaded fuel like my friend does with his 13.5 to 1 compression v8 motor. Good luck getting some. there are a couple stations that have it out here but they are way out in the boonies and you will catch hell (big fines) if they see you actually putting it in a car's tank. It's supposed to be for offroad use only

 

[ekanddsm]

I have ran 12 to1 in alot of duratecs and hondas. Newer 4cylinder aluminum heads that are 4 valve have great combustion chambers that dont detonate easy they burn fuel better than a old v8. I have run hondas with 11.8 to 1 on 89 octane you just have to tune if you want it to run good

 

[DJYoshaBYD]

yeah.. a honda b18c (gsr) block with b16b (ctr) pistons, and a b16a (civic sir/si) will bump the compression up to about 12:1 or so.. A friend of mine and I built this motor, and its tuned for 91, and it works great... you can run that high if you can get it not to knock, but if you want it a lil faster, then just give it a good bump in compression from stock, some good rods, and a free breathing head.. along with I/H/E and a tune, you will have a pretty formidable street car, NA, that would probably shut alot of mouths in your town.. haha.. But, I am always for the underdog... I wonder how far you could take a 420a in the street.. I will have to look it up..

 

[dsm_4g63]

well wouldn't methanal increase the octain levels in the cumbtion cambers.. i was also looking at a swap to a pt cruiser gt turbo for the car its ran off the same block, but that might be alot harder to do than i want it to be. but like i said i'm not really familair with this motor i'm been learning about the 4g63 for about 6 or 7 months now.. but i do believe i've seen some one out in the gut in albany with a 97 with a 420a n\a and it smoked the shit out of my freinds crx with a K20Z1 swap with bored out an nippin forged pistons high flow fuel\oil pump and alot of other this i can't remeber fully gutted and the car top out at 180mhp before the motor blew.. so i do know this car does have potenal with out a turbo.. but theres no go like turbo thats for sure..

so if i was going to get such a high CR out of the car. the main consern i had was the deliever of the fuel or the VE that i would need to parts for to obtain.

and once again i know nothing of the 420a so maybe the head internals might need to be changed as well for the high CR dual spring? stronger vaules or should i get the bored over size vaules maybe 2mm on the intake and .05mm larger on the exhaust would defidently inprove the VE a bit.. but i don't know if that would do the trick.. any more help from you guys.. or should i just go lower to 11. compression?

 

[DougR]

Tune it for E-85 and run that compression all day long.
kinda off topic, but my 4.3 S-10 is sitting fat at 11.5. as a daily driver. on E-85 and a holley 2d Projection system, pushing 90 pound per hour injectors on a
wally 255.... Runs GREAT! Tons of mid torque! we aren't even going to talk about the bottem end torque!

 

[DJYoshaBYD]

then again, you are choosing one race between that car and a honda... A simple swap and a few mods vs a fully built 420a isnt really a contest.. and did he have the k20 with 160 hp or 200 hp? 5 speed or 6 speed? who got the better launch.. ok.. screw the launch.. who won from a 30 or 40 roll.. that is where you see the speed of a car that does nothing but burn out.. .. fwd's have that tendency..

dual springs are not for compression.. they are for keeping your valves riding on the cams when you rev really high.. if you rev too high, then you "slap" the valves and they float.... right in to the piston.. all honda's and 4g63's that I have seen are interference motor's, and I could only assume that the 420a is too.. what you really need for high compression, is a good tune, solid head gasket, ARP head studs, fuel system upgrade, and the head to flow enough fuel to make up for the air and compression you are running.. along with aftermarket rods, you will have a pretty savage motor... maybe even keep the cr a lil low, and throw a bottle in it for the weekends.. .. I love nitrous.. its so fun to have 50-100 hp by pushing a button..

 

[DJYoshaBYD]

e85 i believe is 118 octane or something like that.. very knock resistant, but it takes about 20-30% more fuel to ignite...

 

[dsm_4g63]

i'm not really sure what e-85 is really..

but the kit that i was talking about with the 12.5 compression comes with:
eagle forged rods
Clevite 77 main bearings
je pistons
gapless rings set

and i think that the honda was in front until they hit about 40ish or so.. but by a half car length.. the motor int the honda is a stock 206hp or so i believe i maybe wrong so the dsm much of had some serious power thats way i'm looking for a higher CR because it was natrual aspired. and i'm not happy with turboing shit maybe max 8psi pshh i'm looking for the range or 25 to 30. thats why i'm getting a 1g dsm after i get this done and sold..

 

[dsm_4g63]

oh DJ so i'm not really sure of how nos\ zex really works out for cars.. is it the higher CR you have the better it will efect your hp or the other way around.. with lower CR? i was actualy thinking about zex but i've only heard the bad stories and now of the good one.. one freind studiply was stitting in a parking lot reving and hit the magic button and the car went BOOM. so i personal never really seen anyone use it besides that...

 

[DJYoshaBYD]

you have to know how to use is and tune it.. and nitrous LOVES high compression... basically, you are not throwing just nitrous in there; its nitrous and fuel.. and it has to be tuned right.. but thats another topic... haha

really.. I would probably just go with a slightly lower CR, because its realllly high for something that is not a honda.. haha.. kinda kidding, but not really... you need to figure out if you can get enough fuel and air through that head before you jump the CR up that high.. unless you are going to use individual throttle bodies, wild cams, and a 1mm oversize valve.. .. I would love to see a rude ass all motor 420a... it would be sick

 

[DJYoshaBYD]

the boom you heard probably was a rod snapping.. .. never do what he did.. unless you want a 2g paper weight.. haha

 

[dsm_4g63]

yeah his paper wieght was nearly a 10k car now it sits all suspension gone laying body to the ground next to his house...

but i was thinking of going with the machine shop and getting a .05mm on exhaust and 2mm over on the intake i think it was somthing like a 25% better flow on the intake side and about a 35% more on the exhaust side.. but i haven't look or even tried to find vaules that would work.. but i was thinking that at the 12.5 compression arp head studs of course stronger values but i'm not sure what to get. and bigger injectors high flow fuel pump and a super flow air induction. i did hear of a cam for the 420a just for a high compression engine.. would there be other things i should do besides the ones mentioned.. and would this be a good zex\nos setup? or should i still lower the CR