350x motor question

[Preddy05]

So i took apart the 350x motor(figured i would replace the rings while its apart) i just got and it has a high comp. piston in it 12:1 has stock cam but i have a larger cam here i am going to put in it... i am thinking pump gas is out of the question so what octane gas should i run? any ideas?

[SWIGIN]

how did you find out its a 12:1?

seems odd to go with that piston and stock everything else

[Preddy05]

how did you find out its a 12:1?

seems odd to go with that piston and stock everything else

thats what i was told was in it... took it apart and its high comp. so was just taking there word...

[Preddy05]

thats what i was told was in it... took it apart and its high comp. so was just taking there word...

he aslo said the motor use to run... they had it outside with nothing over the intake!!!! for like a month. there was some rust in the cylinder and on the rings but the piston looks like new i'll take some pictures of the cam that came in it and the one i will be putting in it..not sure what make it is but its bigger.

Any way i can take the numbers off the top of the piston to find out what it is? i'll post pic in couple mins have to go take some.

have a spare cylinder on stock bore i will just get send out to get bored to that pison...

numbers on the piston are 4396m08150 XG B00J3...

The one i put arrows next to match the numbers on the top of my piston so i take it thats the one i have?

[SWIGIN]

yup, thats a 12:1.....be ready for the posibility of needing race gas

i cant tell you what octaine youll need but start with the highest you can get and work your way down till it starts to ping...then go back to the octaine it didnt ping on.

if it dont ping on high test pump gas then id say run that

[lndy650]

you cant run pump gas with that piston you need at least 103 octane
try 112 mixed 50/50 with 93

[NOS_350X]

I know several people that run 12:1 pistons on pump gas (91) with no problems.

BUT just double up your head or base gasket and you wont have any problems.

[The Goat]

but wouldn't that lower your compression?

[NOS_350X]

Well hes worried about runnign pump gas on that piston, if he adds a gasket he can and not worrie about the gas.

[christrucker]

On my 4 wheeler that had the 350x motor, I had a 12:1 comp piston and ran it on any gas I had laying around. Never had any problems.

[scrawny]

it will run on pump gas and not rattle itself apart, but it will run WAAAY better on a race gas mix.

[Preddy05]

pictures of the cams.... looks like when its together i will be trying it out on pump gas...thanks for the replys

[NOS_350X]

chitty pics, In the second pic the cam on the left will pull more topend. I think, Put her on and try

[hoser]

but wouldn't that lower your compression?

Yes but you can still brag to your buddys you have a 12:1 piston:crazy: .

[RedRider_AK]

BUT just double up your head or base gasket and you wont have any problems.

Several people have commented on this already, but I feel the need to put in my two cents.

Seems like a waste to have a "high compression" piston and then reduce your compression ratio by sticking a double head gasket in the machine. I don't know, to each his own I guess. :crazy:

[hoser]

Several people have commented on this already, but I feel the need to put in my two cents.

Seems like a waste to have a "high compression" piston and then reduce your compression ratio by sticking a double head gasket in the machine. I don't know, to each his own I guess. :crazy:


EXACTLY!

Many have this illusion of a fire breathing faster than your buddys engine by dropping in a high compression piston, it dont work like that, more often than NOT going high compression creates MORE problems than it solves, to take advantage of higher compression or taking a huge jump in compression like going to 12:1 you also need to change the cam, the cam profile needs to be matched to the piston, then their is issues like ignition timing that will probably need addressed to take advantage of the higher compression, each engine is different, most high compression engines are engineered as a package not just a piston.


IMO if it was my engine I would use this opportunity of having the engine apart to replace that piston with a stock piston...

[NOS_350X]

God dam calm down, the dude is worried about the compression on pump gas, i told him how to solve it so he dosnet have a thing to worrie about.

Hoser- There is no easyer way to pull a ton of hp off of a motor than compression. You take a bone stock engine thow a ton of compression into it and BAM you got alot more power than you had before. You take a built bigbore stroker, throw a high comrpession piston in it and you end up with alot more power. My 450 in my shop is at 16:1 right now. My 350x is 13:1, If you want power you have to do it. If your building a full blown race motor then yes you need to do cam, igntion porting everything, BUT for the avgerage joe just the piston is fine. I dont know about you but a stock engine OR compression motor just dosent do it for me. not enough ponies there.

[hoser]

God dam calm down, the dude is worried about the compression on pump gas, i told him how to solve it so he dosnet have a thing to worrie about.

Hoser- There is no easyer way to pull a ton of hp off of a motor than compression. You take a bone stock engine thow a ton of compression into it and BAM you got alot more power than you had before. You take a built bigbore stroker, throw a high comrpession piston in it and you end up with alot more power. My 450 in my shop is at 16:1 right now. My 350x is 13:1, If you want power you have to do it. If your building a full blown race motor then yes you need to do cam, igntion porting everything, BUT for the avgerage joe just the piston is fine. I dont know about you but a stock engine OR compression motor just dosent do it for me. not enough ponies there.

Your statements here go directly against everything I have ever read about high compression, to think those hundreds of hours and hundreds of dollars spend on books shot to hell:crazy:

[Twilight]

Look at the KIT for the 250r, there's a reason its a kit.

Also think about longetivity of the motor, how long do those stroker engines last? I have seen threads time after time again about how they have gone out.

[SWIGIN]

Your statements here go directly against everything I have ever read about high compression, to think those hundreds of hours and hundreds of dollars spend on books shot to hell:crazy:



your missing the point.......he didnt buy a high comp piston just to lower it

it came in a motor he bought and hasn't run yet, and hes worried about it pinging.....wich it will especialy with a stock cam and such (higher cyl pressure)

id turn it down in a lathe to about 11-1 but thats me