Here is a link to the Popular Hotrodding article on Octane rating vs dynamic CR. based on this curve, you can run 10:1 Dynamic CR with 105 Octane E85.

http://www.popularhotrodding.com/tec...eze/index.html

 

If that link doesn't work, try this.

http://www.popularhotrodding.com/tec...eze/index.html

 

well timmie people seem to be digging the "9:1" badgers but why?
price
easy fit ... the right freakin pin size
it will run on pump gas

if you show them a stockish dieting 400 with the zero deck(maybe -0.010) that burns regular on stock/rv/summit/255DEH cam ya know nothing nuts just the way ford should of if the gas was right back in the day with a bit of power

long story short 9-9.5:1 zero deck -0.010" just make sure you dont screw the buyers that have closed chamber heads by cutting into the quench area

just 1 po-as opinion

ps option 1?? why would you consider making the same mistake as ford??? again

 

...option one was simply duplicating Badger but getting a constant supply- as i understand it. I had a set of badger sell for nigh on $200.00 due to shortage.
Its done and i missed it but TMI now also stocks the right piston for stock- open chamber heads. He has had the KB's for closed chamber head already so I'm thinking and hoping he made this one specifically for the open chamber. If your going closed chamber you might as well go for the specific piston.

Now I see a rebuild kit coming from tmi that will match anything you could possibly want out of a 400.

 

roger wouldn't a zero deck 9~9.5:1 w/open chambers still help or eliminate the dang pinging weve been dealing with for 35 years using a dish rather than just lowering the piston deeper in
pushing more of the hot exhuast out pulling nice cool A/F in

 

True, if done right a zero deck will increase quench. But the flattop still creates 9:1 and is close to what Ford made when they designed the engine- then they left it in the hole and dished it which dropped a point or so off CR.

The flattop is not the mistake ford made- most will agree that the original 400 ('71) was a kickin motor and it allows for decking the block id needed or wanted. The original badger flattop was made for propane conversion but has been used to rectify ford's error of killing the compression.

I would not disagree that zero-deck pistons dished properly for open chamber heads and 9:1 compression is the best option most of the time. But the flattop 9:1 was not a mistake- dishing it and leaving it in the hole was. Also...9:1 is critical for using the 255 cam which many use. I don't think you can get enough quench to reliably and consistently run pump 87 with 9.5:1 and that cam- the dcr is too high (from what I have read and heard) You'd be knocking on close to 8.4:1 dynamic compression. Thats borderline for 92 from what I understand.

Folks are really going to have to be careful with these new zero deck pistons too. theyd best do their research or have someone who knows what they are doing build their motor. You have some leeway with flattops in the hole. all of this is imo.

 

also the amout of exhaust pushed out depends on the volume above the piston on tdc which is the same if you are running 9:1 with both type of pistons...right? one is in the hole the other is dished ...the CR and thus the volume is the same.

 

FYI,
All of our pistons are a zero deck height piston. The last 2 hyper. pistons we have are the stock 400 pin size. The last 2 hyper pistons also are design to be a 9.5:1 comp ratio with either a aussie 302 head or the stock 400 head.

I think (???) we have nailed down most of the popular options for the 400.

Of course we are always looking for other ideas.

 

so what about those going with a 255 or similar cam? I don't see how the dcr is going to work with 9.5 cr. Do they have to have them dished more?
Your build thats on the site had a cam that drained what .5-.7 of a point more than a 255 similar cam?

thanks

 

Tim.


What is the weight difference between a stock down in the hole piston and your "0" deck. I wonder is this is what ford may have been trying to do,that or they are just stupid lol.

 

stock 1.67
replacement 1.65, oddly the same height as a 351c replacement both vary
TMI 1.72
so roughy from stock .05 from most replacement slugs .070

ford dropped the original flat top down the cylinder to reduce compression and shot them in the foot with the event of crap gas and emmisions regs from the 70s and the tendincy to ping they had to dish the pistons to drop the compression more, retard cam timing and starve the motor

sorry on posting i noticed weight Q not height..oops
now the 400 is a low rev motor usually done the power band by 5000-5500
also the 351m has a huge heavy slug of ~1.92 compression height
the 351Wheezer ~1.75

 

So has anyone used 9.5:1 cr with a low duration cam like the 255deh or sim? Wondering how that works.

 

"Of course we are always looking for other ideas"

Have you given any more thought to the budget stroker kit I mentioned?

Offset grind 4.17 stroke, 240 I6 rods & ACL 1.405-1.415CH pistons.
KB used to make a FT piston that would work with this application. 4343H if my memory serves.

What I'd really like to see is a new budget dished piston so you could use a closed chamber head and not end up with 13+:1 compression.

 

Brian,

Have you looked at the compression ratio chart?

http://www.tmeyerinc.com/pistoncompare.html

 

"Have you looked at the compression ratio chart?"

I just did now. What did you want me to notice?