Hey all,

I've been reading posts here for some time, and I've been trying to come up with a plan for the engine for my truck. I posted my "howdy" to everyone on the introduction thread, but I didn't really get into any particulars.

My truck is a 79 F250 Ranger XLT Supercab Trailer Special with a 400 under the hood. Well, that's not true, as the engine is in my garage, and the truck is currently at the body shop getting painted.

Anyway, I've been reading the input from everyone about various plants, and it seems that there's always a heated discussion when it comes to the 400 vs. 460 route. Now, while I do have a 460 in the shed that I could probably use, I don't know it's history, and I've been reading enough about the 400 to know that it's a damn good plant if built right, and used for the right purposes.

I think it's a fair statement to say that the intent I have for my truck is an all around cruiser, camper, hauler, tower, and the occasional 'gettin into crap to see if I can get out' sort of beastie. That being said, I can't see why I'd need a high rpm engine, when torque is really where I'd be living. Also, to offset the need for function at higher rpm's, I'm looking into an overdrive unit from Gear Vendors to attach to the back of my transfer case to make the motor happier at highway speeds.

Currently, the behemoth has a Dana 44 up front, and a 60 in the rear, with 4.10's and a C6 transmission. The transfer case is a NP205, which I've already had rebuilt. I've noticed that highway speeds tend to keep my 400 running a bit higher than it's comfortable, and I figure an overdrive unit will drop the rpm's, and potentially help gas mileage (although noone here can say they really care about that that much with these trucks).

Now, onto the main question I've got mulling around in my melon. I've been looking a lot at Tim's stuff, and from what I've read, the cast iron aussie heads that are built right seem to be the way to go. The question is: How are these particular heads for longevity?

I haven't settled on whether or not I want to build a stroker at all, as from what I know, strokers tend not to live quite as long as stock configurations due to increased stroke angle, etc. I do, however, think that I'd like to do a full roller conversion, as I've been looking into the Comp cams that Tim talks about. Also, I've already got the Heddman long tube headers, the Edelbrock carb (I think 625cfm), and an old Edelbrock Performer 400 intake. I figure if I can get the block built right, and add the aussie heads, power should be more than adequate, and torque should be pretty much stump pulling territory.

I've got time to figure all this out, as I won't start building the engine until spring, but I want to start getting my research done before I actually start (that, and I have to pay myself back for the paintjob, which is a tad spendy).

Anyway, I know that's a lot of writing for just asking how the aussie heads hold up, but I figured since this is about my first post of any substance, I should put the general plan out there.

Any input is appreciated. 'later

tim

 

Aussie heads are good quality cast iron heads. With the right parts, they will hold up as well as any head. They should be rebuilt with hardened exhaust valves, new valve guides etc. Stainless steel valves will help longevity on any head.

Aussie heads have quench chambers, so you can run a little higher compression ratio without detonation. That will help in the power and mileage department.

The extra power will show up as more torque at all RPM ranges. The open chamber heads probably flow a little better in stock form, but if you do a little porting work on the Aussie heads, they will flow as good or better than stock open heads.

 

stock Ford valves have been known to end the longevity of quite a few engines and rather abruptly. the valve head separates and extreme chunkage commences. consider 1 piece valves a priority.

 

you can run a lot more compression with the oz heads... not just a little....i think... Still looking to get enough raw data to plot it out but i suspect you can go more than .5 higher (about the same as aluminum?). (not confirmed scientifically by any means) but good enough for my $. If you want even more power look into the 4v closed chamber cleveland head...same quench but a lot more flow. You basically make a 4v stroked cleveland.

I built my 400 for similar purpose...same really except propane and i'm running pump due to the quench of the oz. Calculator says i need 95+. You would need to do a bit to a 460 to beat it...sure it can be easily done due to cubes but close to 400hp and 450 ft lbs is a decent build. And i do expect to get some decent mileage which will not happen with a 400hp 460 build. I have a 429/460 in a '79 bronco that will be replaced with a 400...no doubt about it...better motor imo...unless wanting to make wicked power.

ci for ci I am comfy (thus far) saying the 400 is probably the best for older push rod ford (truck engine)...thats why it was run on the recent engine masters challenge. The cleveland did really well and is likely the best ford ever made...

and it's going to be nice showing how the 400 rocks... to those boat anchor theorists (like I used to be).

 

im not trying to bash on the 335's or anything but the only reason the engine masters, like john "god" kasse used them was because of the aftermarket heads. if you go to CHI's site there is an interview with him about it and thats what he said...

ps. i think he should send me some chi heads free of charge

 

Behemoth,

I think you have given this whole thing lots of thought and are on the right track. The 4 inch stroke of the 400 can make for a very good torque motor for towing and turning those big tires that you probably have in store.

Because of the weight of the vehicle you are talking about, coupled with the big tires, I really believe that you will find an overdrive will offer only a marginal if ANY increase in fuel mileage.

The number one factor in fuel consumption is vehicle weight. Big tires will soak up even more torque. The 4.11's will be just about right, and if the engine spins on up, you may very well do better on fuel than if it were at a lower RPM with such a large load. There are too many variables in this equation to speculate really accurately, but the time I've spent with my 400 with different size tires under varying conditions lead me to believe this.

The key to building a good 400 from both a torque and fuel economy viewpoint is getting enough compression and the Aussie heads are the way to get it.

Keep us posted on your build. The truck and the engine sound fascinating.

 

MBDiagMan,

You're right about the tires. While I'm not going insane with something like 44's, I am running 35's, which is still a relatively large tire. I opted for the Toyo MT's as while they have an aggressive tread pattern, they still have remarkably good highway manners, and from what I'm told have ridiculously long treadlife for a mud terrain tire. They're not cheap, but seemed like the best choice for me. Also, the 35's seem to match the look of the truck just about right. Any bigger, and it would look forced to me, and any smaller wouldn't match the size of the truck (granted, just my opinion about my truck, not anybody elses).

As for the overdrive unit, I'm not as sure I agree, but I have time to do some research. When I was still driving the truck before I took it apart, I had the opportunity to weigh it, and dead empty the thing weighs just over 6200 lbs (and no, it's not all attributable to my fat ***). My point on the overdrive being able to help with fuel economy on the highway is based on the idea that once the truck is at speed, you've already overtaken the inertia issue due to dead weight. The mass of the truck is already moving, so the engine wouldn't have to work as hard keeping it that way. Now, if you add a gear that will reduce rpm's, but still well within the torque band of the engine, I'd think the engine would potentially work less, hence upping fuel economy a bit. Granted, I don't expect massive increases, but for any highway trips, I think it could help a bit, and also reduce wear and tear on the plant.

The other benefit of the GV overdrive unit is that it's also a gear splitter. So, in essence, it can be used to make a 3 speed C6, more like a close ratio 6 speed. This could help with towing, and reduce strain on the transmission. It also could help with acceleration, but as I stated that's not the intent of my truck in the first place. Besides, how fast could I get 3 tons moving in the first place?

Anyway, that's kinda where my mind is on the overdrive, but I'm not completely sold on it yet...we'll see. 'later

tim

 

behemoth:

on the research I've done i would disagree with diagman vs the overdrive as well. It should help economy...the only way it wouldn't is if you didn't have enough torque to turn the wheels due to overall gear ratio... and you use it too much.

I think the key will not be in your final ratio but using the six gears to keep the engine in the right rpm range for a much longer period of time regardless of conditions...coupled with a flat and generous torque curve and your on the money....imo.

You might not use the top or bottom gear as often as you would think...but you might too...

 

I don't doubt that with all those gears to choose from you will be able to come up with a fuel savings, but it will be somewhere between miniscule and immeasurable.

The NUMBER ONE factor in fuel consumption is WEIGHT. Adding the tires you speak of will be similar to adding several thousand pounds of weight. 35 inch tires and wheels weigh AT LEAST 100 pounds each. That means 4, 100 pound flywheels that you have to accelerate AND keep rolling. I am not degrading the running of large tires. I have done it myself, and my 2000 F150 has 33's on it as we speak. What I am pointing out is that they soak up LOTS of power which, of course, takes fuel to develop.

That said, it sounds like there are other benefits to the overdrive due to your expected vehicle usage. With that being the case the overdrive may very well be worth the trouble/expense, but if you expect to pay for the overdrive with fuel savings, I think your kidding yourself.

In theory an overdrive always sounds attractive to someone who craves fuel economy. You say that once the truck is moving the engine "won't have to work as hard." Not true, the engine must deliver the same amount of power for a set speed with a given weight. If it is turning 500 RPM or 5,000 RPM the truck will still require the same amount of energy to keep it moving. By developing this energy at a different RPM range you MIGHT be able to find a more efficient RPM range, but a 400 is not a good candidate for such expectations. These engines have broad torque curves.

If you lower the RPM for a certain speed, the throttle will often have to be opened further to maintain speed at a lower RPM.

An overdrive is a wonderful thing. I am only saying that I expect the fuel savings to be minimal and will take many miles to pay for the overdrive.

Please don't construe my comments as discouragement toward your project. I am quite interested in your project and hope to hear lots of reports, details and findings along the way.

My $0.02,

 

So if "The NUMBER ONE factor in fuel consumption is WEIGHT"

then why does my RV that is 38" long & 18,000 lbs, pulling a mini-van get 8mpg?

at least 3 times heavier than the Ford pick-ups, yet not a lot less MPG???

Just curious

 

Well, before this discussion goes way off the deep end about fuel consumption, I think it best to remind folks that in my initial post, I said, "and I figure an overdrive unit will drop the rpm's, and potentially help gas mileage (although noone here can say they really care about that that much with these trucks)".

So, from that, I think it's clear that I wasn't too hopeful about fuel savings with the OD unit, but rather more as an ancillary benefit, if at all. I am more interested in the OD unit to help keep both the engine and the tranny happy by not stressing them out as much by being able to stretch gears and rpm's over the entire torque band of the truck. Any gas savings, if any, would simply be a bonus...not the principle aim.

So, before everyone starts going off about the fuel issue, I'll just say that my actual question was about the aussie heads. To that end, I was snooping on the CHI website today, and was curious whether or not their heads are a better way to go for my application, or if the aussie heads are comparable for what I'm trying to accomplish. I'd still like to stick to a cast iron head, so maybe CHI wouldn't be the best choice. Not sure.

Anyway, hope I clarified my point, and steered this back to the topic at hand. 'later.

tim

 

Since we are on the subject of the Aussie heads, one thing I have been wondering here. Do the closed chamber heads burn fuel more efficiently then the open chamber heads? Meaning if Im aiming for a cretain CR would it be better to go with closed chamber and matching pistons to achieve (lets say) 9.0:1 or is it more efficient to have open chamber heads with matching pistons to get the 9.0:1?

 

I don't know of any data that will supply an answer to that question. However it is the wrong question. You need to compare closed chamber heads with 9.5:1 CR to open chamber heads with 9.0:1 CR. This will compare motors that run on approximatly the same grade fuel. The answer to this question is that the motor with the higher CR will give better fuel mileage.

 

So if you have closed chamber heads you can run a higher CR on the same fuel? When I said burn more efficiently I meant a more complete burn of the fuel which I suppose would translate to more milage plus more power or is the fuel completely burned off either way.

 

The fuel is never completely burned. The open chamber heads are more environmently friendly. They will burn cleaner, but that doesn't translate into mileage. Higher compression and a dirty burn will produce more power and better mileage. It has more to do with the pressure waves created by the burn, than the burn itself.