maybe around 12.1 if there was any cleaning up of the surfaces eh? and with a low duration/lift cam your likely to be way above the percieved 9.5:1 ceiling on dynamic compression- could be 10.5+:1. I'd love to see it run.

definite science project...do not fail to keep us informed...or me anyway. I may be up in Polson on Sat but definitely not on Sunday. Possible to meet?

 

Yeah i just got ahold of the machinest yesterday and yep they are the new KB hyper's , dunno how but he got a set, now he said they were a flatop soo weather he had a set made without the dish or got a set before they went off to machining i really don't know, but i'm heading up there today to drop of a crank and rods and they should be in by now, so i'll take a look and see if they a true flattop or a slight dish in em'.

Also the machinest was saying he could deck the block to gain a bit more as well, so i think we're going to do that as well so i think i might just end up in the 12:1 range , and the cam i'm using is the comp 275 deh (.515/270*int and .541/280*exh) so i think your not to far off on the dynamic ratio there, i guess i'm going to need a bit better gas than premium wouldn't you say (and there inlies a bit of a pita, nearest place i know of to get race fuel is a 3hr drive, unless i run av gas and get some additives for it).

 

odd looks like those zero decks aren't quite zero if he can deck the block much
i would definately see this thing before the head is on

 

Get us a part number on those KB's. This will answer everything.

KB does not make single or small runs of pistons.

Now remember, depending on how much they resurface the block, you may have an intake situation.

 

Yeah i'm aware of the intake situation, but i would have the intake spacers machined to take care of that issue so i can still use the cleveland intake.

As far as the pistons are concerned i do know that they are a new zero deck (how close to zero deck is something i do not know, but they are not down the hole like the badgers are) and that they are a new piston from kb, we didn't get the chance to go up today butwhen we do i'll grab the part number.


Roger, the bog is at noon on sunday (thats all i found out), but sadly we've decided not to go cause theres just to many other unknown's, but next week there's one in great falls if you're interested.

 

This thread is interesting, and it's good to see the 400 getting some good options.

Two things I don't understand are:

Why would anyone use a dished piston with closed-chamber (quench) heads? The "quench" effect is the flat top piston "quenching" the flame out as it squeezes up to the "closed" part of the chamber. A dish would take away any benefit, would it not? Might as well just run open chamber heads than waste a set of quench heads like that.

Second, what is the fascination with the 255 cam? Seems like it would make more sense to select a cam grind around my piston/compression, rather than vise-versa. Eliminating what few good options you might get for pistons on an engine that typically hasn't had any good options just to keep a certain camshaft baffles me. Any Cleveland cam will work in a 400, and there are many grinds - even custom if you want. Run the 9.5:1 compression and select a better cam. Or am I missing something?

 

1st - Research has shown that th best quench comes from dishing the piston to somewhat mirror the combustion chamber then to get rid of the flat space by putting the piston further up the hole- ie zero deck. I've read that a football shape combustion area is highly desireable.

2nd - your kinda right imo - the point with the 255 that i've been trying to make or warn against is that it is a very, very popular cam (probably the most popular) and with the badger pistons it worked well but now that option is waning and I bet folks are going to be putting it in with the kb's and have major ping. So the new pistons now create a lapse for those who want the basic rv/mileage build that is so popular. I wasn't aware of stangs cam choice and it will still be very interesting to see how it does. Also the 400 has had some decent options for a while and as a stoked cleveland it is a kickin truck motor for those who want 300hp and 420ftlbs and better mileage than probably any other ford v8 in their truck.

You shouldn't be baffled about the cam selection as cams represent the type of performance you desire and you build the compression and other components to match the cam. haven't heard much of the opposite since the cam's the brain and defines all else thats needed.

if you want a high end race motor you need to be able to spin or make major cubes and i don't think the 400 will ever be the best option for that...even with the stroker option. I'd get a man of war windsor block that make 460 cubes and go from there but for a truck engine ....

I think i will have about the best truck engine i could get with my 400- retro hyd roller cam- custom grind (262,270 adv)- roller rockers, and kb's with quench heads..if i don't screw it up putting it together.

i could be wrong on the above...all or part but i doubt it..cause i've been learning from folks here who know their cheait.

 

The heads, cam, and block should all work together to produce the optimum results for a particular application. The 255DEH cam is the first choice for a pulling truck with an otherwise stock motor, although a HR version would be slightly better. A longer duration cam will give up low RPM torque in order to produce power at a higher RPM.

Improving CR will also help at all RPM ranges, but it is limited by the dynamic CR and fuel used. Quench and aluminum heads will allow higher DCR.

Improving head flow will extend the RPM range of even a short duration cam, like the 255DEH. So you can have a motor that pulls hard at low RPM, but also continues to pull up to 4000 RPM, but the cam will need higher lift than a 255DEH to take advantage of the head flow. A HR cam should be used with better head flow.

The final answer is to build the motor as a system, to perform as the application requires. That does not mean to maximize HP or low end Torque, as people are prone to do, but get the best match for the application.

 

I always heard that you want the piston to basiclly extinguish the flame as it squeezes up, from the flat part of the head towards the plug. Maybe I've got that wrong, but a dished piston wouldn't do that. Why wouldn't Ford have put dished pistons in the quench 4Vs/Boss351 engines? You could be right; I need to look into that one more.


See, I do that just the reverse; I try to figure what compression I can live with fuel-wise, and how I want the engine to perform, and match the cam, induction, and exhaust around that. I want them all to work as one. With an engine like the 400 where you have a sparse set of piston options, I'd think you'd want to match the cam and it's timing events to the pistons/heads, etc. The cam will have the biggest effect on how it performs, but it all has to match, and to me it's easier to match to the rotating assembly first. It's the hardest part to change.

if

 

Upon further review, I stand corrected about the dished pistons and quench heads. Good info to know.

 

I think thats saying the same thing in a different way..maybe

 

Whats wrong with using the Comp 265DEH, Badgers, Port and polish, with no alteration of the deck. I managed to find a block that didn't have any variance and I didn't want to cut on a block that didn't need it. I do have another block that does need to be cut .020" and I'll be getting pistons from Tim, I like the Number 2 option, but what cam do I want to run. I'm not sure on a HP/Torque goal, I want it up there and I don't care about gas prices, I ride my motorcycle that gets 52MPG everywhere I don't need a pickup I don't have E85 available in my area, and its going in a technically much lighter 79 F150 2wd. I have the fibreglass front end and box from www.usbody.com I got the heavy duty parts (you have to love a box that weighs 50 lbs. and is every bit as strong) I don't have a specific weight of the truck yet, I'm trying for 2800 but I'll be closer to 3000. I bet I'm losing 600 lbs in steel and the only metal I've added is boxing the frame (fishplate) and four linking the rear and adding a sway bar. I have 3" drop spindles for the front and changed the rear to adjustable air bag coilover shocks.

This was originally my V10 project, but I was able to procur the fibreglass parts and paint for less than a donor van with 250000 on the V10 and tranny, which would need to be rebuilt. If anybody has any questions, these fibreglass parts are absolutely top notch and gorgeous.

 

I like the tilt front end...i had one from a big fire truck land on my head and re-arrange my neck bones..but for racing it would be nice.


As far as the badger and 265 cam...it's a popular choice too but the badgers may become a bit harder to find now.

 

Great thread!!
I am getting ready for my 400 build, and I was exited about the new piston design, but it looks like the experience here says that the 255 DEH cam is a bad idea with the new hyper piston due to the DCR. I am not necessarily looking for a torque monster, but I do want to get the best economy possible. From experience, is stepping up to a 265 cam going to kill economy, or should I stick with the 255 cam and the badger pistons? This is going in a F250 4x4, with an E4OD.

 

I have the Badgers, 265DEH, big valves (2.07 Intake) and port and polish on a 400 in a 150 4x4, and its a stump puller... Not sure on mileage, still in break in technically, but looking much better than the stock motor was at 8 mpg.