If i put a 440 kit in a 400Ex would I have to run higher octane fuel or race gas? Also does it hurt the engine a lot and to anyone out there with a 440 kit is there a big difference in power
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I don't much on this subject but on almost all 440 kits that I've seen. The compression is raised therefore meaning you have to run race gas or high octane fuel. The increase in power is very noticable but like most things add a bigger carb, cam+oversized valves, and a better pipe then its like night and day.
later
Superstar

 

yes you will have to run at least a mix of race fuel and premium pump gas with 11:1 compression or anything over that,no it will not hurt the engine if it is built correctly and yes there will be a very noticeable increase in power if the 440 is tuned and jetted right.

 

I have a 440 with a 11:1 piston and it runs fine on 93 octane.

 

A 10.8 to 1 compression 440 can and will run fine on pump gas and is more reliable. I run 13 to 1 and every three months I am changing head gaskets and definitly need to run race gas (110 octane). I haven't been beat by another 440ex. I think a 10.8 to 1 piston and a web 450/451 (all around) cam will work fine. You should be able to run right next to raptors with this kit.

 

I am going to buy one of these with these mods to...White Brother E-Series Pro Meg Exhaust system, DG front bumper, dg grab bar, dg nerf bars, 440kit, twin air filter, renthal bars, jet kit, ITP T-90 Pro Series Wheels, and ITP mudlite tires. Do these sound like good mods to put on or if there are better ones tell me your recommendation..I was just wondering how fast a stock 400EX will run and how fast will a 440EX with the mods I listed above will run? By the way does anyone know where I can find a 440 kit and how much do they cost?
Thanks

 

They will both run about the same speed unless you change the gearing. You will just accelerate faster.

 

So...a 440EX with mods I listed that I am going to put on mine wuill run the same speed as a stock 400EX I dont think so....What is the top speed for a 400EX 70-75???

 

What does everyone think, how fast will a 440EX with the mods I listed in a previous post that I am putting on mine, how fast do you think the 440EX will run with the mods and how fast you think a 400EX stock will run? Also where can I find a 440 kit and how much do they cost??