those of you with 426's i need your help

[trx400EXtreme]

im gonna build my motor, but i cant decide what to do. im leaning towards a 426 but dont know if i'll be happy with it.

[416exfreak]

You know my vote and why I voted for it;)

[trx400EXtreme]

yea i dont even have to look at the results lol. damnit why does this have to be such a hard choice.:mad:

I do not have a 426 but a 426 is the biggest I would ever go on a 400ex bore

[250exkid]

can you still run the 11:1 compression ratio on the 426cc kit?

cant see why not. The cylinder size shouldnt make it so you need a higher compression I dont think. Its just higher compression is making your gains worth while

[trx400EXtreme]

yea no matter what i do it will be 11:1. right now im about 70% 426 and 30%440.:ermm:

[416exfreak]

Bore size has nothing to do with what compression you can run.

You can run 11:1 in every bore. 406, 416, 426, 440....etc.

I would go ahead and run 11.5:1 or 12:1, but thats just me. Depends on wether or not you can get ahold of some race gas or octane booster.

Dont listen to the jackasses that tell you you can run pump gas in a 12:1 400ex engine, "just because a 250f has 12:1 and uses pump gas".:rolleyes:

[Ruby Soho]

I have 11:1 in my 440, theres plenty of power there.. don't think that you should run 11:1 only for the pump gas reason, its not like theres no upgrade on it.

I vote 426, because if they blows you can move up again to a 440 and build that however for more power when your ready

[trx400EXtreme]

Originally posted by 416exfreak
Bore size has nothing to do with what compression you can run.

You can run 11:1 in every bore. 406, 416, 426, 440....etc.

I would go ahead and run 11.5:1 or 12:1, but thats just me. Depends on wether or not you can get ahold of some race gas or octane booster.

Dont listen to the jackasses that tell you you can run pump gas in a 12:1 400ex engine, "just because a 250f has 12:1 and uses pump gas".:rolleyes: yea thats the only problem i face... is running race gas. we can get it easily, ive got family who races sprint cars, family who drag races..... but at my income.....which happens to be NOTHING, i cant afford it. im thinking no matter what i do im gonna get 11:1. i'll prob just run 93/94 octane.

[416exfreak]

Originally posted by trx400EXtreme
yea thats the only problem i face... is running race gas. we can get it easily, ive got family who races sprint cars, family who drag races..... but at my income.....which happens to be NOTHING, i cant afford it. im thinking no matter what i do im gonna get 11:1. i'll prob just run 93/94 octane.

Sounds like a plan!:)

You could always nab a 2 liter bottle of 110 here and there:devil:

[trx400EXtreme]

we run 110 when we go to the dunes.:devil: its crazy that you can actually feel a diffeence.

[416exfreak]

Originally posted by trx400EXtreme
we run 110 when we go to the dunes.:devil: its crazy that you can actually feel a diffeence.

I run 110 all the time...I love the smell.:devil:

[randallp1]

i have a 426 11:1 port polish and stg 2 cam and it runs its butt off. 94 octane shell vpower and run it all day!

[scruff_mcruff]

Originally posted by 416exfreak
Bore size has nothing to do with what compression you can run.

You can run 11:1 in every bore. 406, 416, 426, 440....etc.

I would go ahead and run 11.5:1 or 12:1, but thats just me. Depends on wether or not you can get ahold of some race gas or octane booster.

Dont listen to the jackasses that tell you you can run pump gas in a 12:1 400ex engine, "just because a 250f has 12:1 and uses pump gas".:rolleyes:

once again your ignorance is shining thru. only some of the piston companies take into affect dome size on larger bores. but some have it set up so every next bigger size piston has .1-.2:1 more than the size smaller. http://www.rosspistons.com/uploads/m_honda_xr400.pdf
and there are quite a few of us"jackasses" that have our own 12:1 400exs that run pump gas just fine on this board. the 250f and 450r references are for people such as your self that have 0 knowledge outside what others have told you is right. If im building a motor for someone that has no idea what they are doing im going to tell them to run as much octane as they can for knock control. but if you have some that understands motors and tuning you can get away with alot less. and once again your giving advice to something you clearly dont understand to another person that dosnt see anywhere close to the climate you do, so how is your tune up going to remotely be relative to his?

[F-16Guy]

You can, in fact, have exactly 11:1 compression in every bore size possible. You can also install a 10:1 piston and have an 11:1 compression ratio by milling the head to adjust the combustion chamber volume. Does that mean that every piston manufacturer offers a piston that is exactly 11:1 in every bore size? No. What it does mean is that, depending on how you set it up, 11:1 can be achieved with any bore size, as 416exfreak was eluding to. Also, the air cooled, radial four valve 400ex engine creates a lot of heat, which contributes to the probablility of detonation when using a high compression piston. If you're running a 400ex with a true 12:1 compression ratio on pump gas, please tell me what your setup is so I can do the same. Every engine design is different, and depending on certain factors, such as cooling type, bore, stroke, combustion chamber shape, etc., the same displacement engine may be able to run a higher compression ratio using the same octane rating fuel.

[cals400ex]

our 440 build was slower than our 416 and our 426 builds. it revved slower. top end was pretty poor in comparison as well. i would say a 440 is good for low end power. it had a lot of power right off of idle. for drag racing we had best results with the 416 and 426.

[axel400ex]

For all around performance and heat build up in mind the 426 is the better choice.:cool: