3500/3400 cr

[zofo61]

What is the highest CR I can acheive with a 3500 top...3400 bottom and stock forged pistons.......what head gasket combo will give me the highest possible CR....?

THnaKS

Chris

[3400-95-Modified]

Stock forged pistons?

Doesn't exist...

Factory parts and a 3400 head gasket will net 9.15:1 IIRC... Iron head gaskets will raise it but also lessen your clearance from the piston top to the cylinder head, so only 3400 head gaskets are recommended for the 3400 bottom ends.

[zofo61]

Forged pistons in a stock bore..........Arias...........so the 3400 head gasket will be used. Thanks for the info. Sorry for the confusion.

[IsaacHayes]

Uhm, as high as you want with custom pistons... LOL.

If you have a rowdy cam then 11.5:1 is ok for pump gas. But with boost, that throws another factor in.

[onefastV6]

3400 bottom end with stock spec pistions and stock combustion chamber 3500 head, you are looking at about 9.10:1 ~ 9.20:1 CR

[3400-95-Modified]

Uhm, as high as you want with custom pistons... LOL.

If you have a rowdy cam then 11.5:1 is ok for pump gas. But with boost, that throws another factor in.

You missed the question on specs of the build.

What is the highest CR I can acheive with a 3500 top...3400 bottom and stock forged pistons.......what head gasket combo will give me the highest possible CR....?

THnaKS

Chris

He didn't say how high can I get the compression with a 3400 block and 3500 top end and "Custom Pistons" he stated that he has stock form forged pistons, so the highest is 9.20:1 and thats getting lucky.

Out of all honesty a 3400/3500 hybrid is a Boost build to start with factory specs, but yes with higher compression (custom pistons) you will get more power n/a.

[kwhauck]

i thought 3400 bottom end with 3500 heads was more like 8.95-9.05:1?

Anyways, i got a set of pistons for sale with a 10.2:1 compression.......

[3400-95-Modified]

Not according to the CR calculator. I used all the 3400 specs including headgasket since I'm using a 3400 headgasket and my cylinder heads are stock, so I assume they are the measured CC's minus a minimal amount since I had them surfaced... But this is what it comes up with just the CC's changed for the heads.

[zofo61]

You guys are kiling me........If I use stock sized forged pistons with the 3500 heads on a 3400 block with the 3400 head gasket....what is the CR?

and if kwhaucks pistons are better for boost.........let me know cause this shit is getting really confusing. Thanks

[3400-95-Modified]

Your CR will be what i posted above if your using all stock dimension parts, forged or not. Now if you use a piston that says it will be 10.2:1 on a 3400 to get a general guess on the CR you can take the 9.5 vs 9.16:1 difference and subtract that from the 10.2 but if you know the new piston dish size the go to the cr checker on this site use all the numbers I did above but sub in your new piston dish or difference in bore dia an run the calculation.

Does that help?

[zofo61]

I guess.......I just want to make sure that the pistons I bought are going to give me the highest compression for boost thats best for my application. I am confused....if the other pistons are better......then I will buy them...if mine will work as well...then I will use them.............??????

[zofo61]

i thought 3400 bottom end with 3500 heads was more like 8.95-9.05:1?

Anyways, i got a set of pistons for sale with a 10.2:1 compression.......

On stock rods or on SBC rods.....??????

[kwhauck]

stock rods or SBC rods, they shouldn't affect the compression ratio.....

[zofo61]

stock rods or SBC rods, they shouldn't affect the compression ratio.....

I know that.....what I was referring to was the pin size.........are the piston pins sized for stock rods or SBC rods...the small end is different.................

[kwhauck]

oh they were made for stock rods, but you can just have SBC rods bushed out.......