Trick Flow 170cc heads too small for a 393?

SubSonic wrote

I'm not quite sure which kit I'll end up going with. If I get the Trick Flow heads I may try to make use of the pistons that Trick Flow makes/sells for their heads so I don't have to worry about fly cutting and/or clearance issues.

I'd think the highest compression I could get away with using aluminum heads in sweltering SE Texas, with 87 octane, may be around 9:1, not totally sure though.

If you are willing to run 93 octane you should be good with aluminum heads up to 10:1 compression.

My 302 build is right at 9.44:1 compression with the goal of running regular grade with aluminum heads

That price is for the as-cast versions, 2 heads.

The 11R versions are $1799 per pair, which is the lowest price I could find anywhere.

I was looking for a desktop dyno type deal. I need to do that.

As for the port cross sectional area, I figure that ideally it would be the same as the entrance to the runner on the intake manifold.

If it's bigger or smaller, port match one or the other? I have heard port matching helps, and then I've heard that it's a waste of time.

I'm interested to learn how the head's runner volume affects the max power and power curve of a motor versus the port's cross sectional area. I'm all ears if anyone wants to help an engine-building noob!

I appreciate y'all's input so far.

DD2000 is a good program but its results are only as good as the information you put in.  You can put in faulty information and get a 600hp peak rating just by inputting bad information.

While this isnt a 393, this is what DD2000 came up with for my 302 roller build for my truck running 165cc AFR heads.  It falls fairly close to what BluePrint claims their 302 crate engines with their in house non CNC machined aluminum heads which tells me the 383hp/406trq has a decent chance of being what my build makes but realistically I expect it to make between 325hp and 350hp which exceeds my goals when I started my build of 300hp.



If you do play with DD2000 just take the results with a grain of salt if you are at all doubtful about the accuracy of your information you are putting in.  For mine I had to play with the cam specs a bit to get the valve timing to match up with the rest of the cam specs by using the advance/retard function since my cam is actually ground with an advance into it which is why the software was getting me different valve timing than specs.

Thank you, I'll check that program out.

As for MPG, would it be an accurate guess to assume a mild 393 with a 5-speed manual transmission could be more fuel efficient than a hot-ish cammed 351 with a 3 speed manual transmission?

My thinking is that the more efficient and better flowing heads, custom spec'd roller cam, and overdrive could actually get better MPG than the motor that's currently in my truck.

The cam in there now is pretty lopey, and I can tell it's probably not the ideal cam for a truck. It has a Performer RPM intake and headers, though they look kind of small. NP435 4 speed, but 3 usable gears due to the granny 1st gear.

I was doing some reading on other forums and places where someone would swap a 289 or 302 for a stroker Windsor or mild big block, and would get better MPG than before due to the fact that the engine did't have to work nearly as hard to get up to speed and maintain it. Assuming their foot was kept out of it. That's my thinking here. I'm currently getting about 8 MPG combined.

Thoughts?

Its possible to see a improvement in fuel economy.  Im hopeful to go from the 12 city 14/15 highway to 16/18 city and 18/20 highway with my build I am doing.

It also is heavily dependent on your driving style and driving speed.

Closest I can make to a comparison engine size wise, my '78 Mercury with its original 351W with a yellow strain relief DSII ignition was putting 27/28 mpg highway down at 70 mph and easily got 18 in the city.  So I do believe it is possible to see a improvement in fuel economy but its hard to say how much and if your specific build would be one lucky enough to see a increase.

For mine I am trying to piece everything together to work together most efficiently for daily use as I want to maximize fuel economy considering I have only a 16gal fuel tank and I dont want to be stuck with 12 mpg city like I was.  I used to get 14/15 city before they switched to the ethanol blended fuel then my economy dropped down to 12

SubSonic wrote

I was doing some reading on other forums and places where someone would swap a 289 or 302 for a stroker Windsor or mild big block, and would get better MPG than before due to the fact that the engine did't have to work nearly as hard to get up to speed and maintain it. Assuming their foot was kept out of it. That's my thinking here. I'm currently getting about 8 MPG combined.

Thoughts?

My first thought would be, if you are going to keep your foot out of it, what do you want a 400hp engine for?

It is certainly true that driving style has a lot more to do with MPG than almost anything else. I think it was Top Gear (British flavor) that took a Prius and a 5.0l BMW, and had the Prius drive around a track full-tilt. The BMW was to follow, just keeping up with the Prius. MPG results were Prius 17mpg, BMW 19mpg.

But as far as a bigger engine getting better mileage, that's possible to a point. Once you get to enough RPM with the bigger engine that you exceed the breathing of the smaller engine (or at least move out of the smaller engines sweet spot VE-wise), then you've exceeded that point.

The reason that the bigger engine/stroker kit can do that is better torque production. I know everyone gets hung up on the peak HP figure, but to me that's a ghost, especially in a truck application. HP is a fairly fictitious number, the product of a mathematical calculation. Torque is what moves a vehicle off the line, and the heavier the vehicle, the more torque you need, especially down low in the RPM band exactly where you are going to be when you are trying to move the vehicle off the line.

My engine build will be geared towards torque production only, wherever the HP lands, so be it.

Consider my old 7.3 Powerstroke having to move that 7500lb dually off the line. HP was an unimpressive 250 or so. But torque - I think it was in the 700's. And it moved off the line quite well.

SubSonic wrote

If it's bigger or smaller, port match one or the other? I have heard port matching helps, and then I've heard that it's a waste of time.

That would depend quite a bit on which way the mismatch falls. If the flow is from larger to smaller, then you're asking the mixture, moving down the hallway as it were, to suddenly cram through a door that is smaller than the hallway. That is definitely not good for flow, any flow speed developed in the manifold will be disturbed by the edge of the head port protruding into the flow path.

Going the other way around is not as bad, but still not great for flow. From a fluid dynamics perspective, if there is a mismatch, it would be better to open up the smaller port and then blend the opening back to the smaller port size over the course of an inch or so.

I would say port matching is definitely worthwhile. But I will also agree that if the mismatch is not that big, you are chasing single digit horsepower. But if your intent is to build a 400hp engine, then chase single digit hp is what you have to do.

SubSonic wrote

That price is for the as-cast versions, 2 heads.

The 11R versions are $1799 per pair, which is the lowest price I could find anywhere.

Summit has assembled 351w aluminum heads for as low as $449 each for flat tappet versions. AFR 185 Enforcer heads, which are hydraulic compatible, start at $599. These are the lower-priced small-chamber heads I referred to in an earlier post.

You're better off to put the 5-speed behind the hot cam.
It's easier to keep from falling out of your skinny power band.
Your truck right now is simultaneously too much and not enough.

My 460 gets better fuel economy than your truck, and my truck carries almost 1,000# of tools in the bed.  
I beat on it every day and usually get 10 around town and 12-13 highway @ 70-75.
You don't need to shift so much if you have a wider spread of power.

Economy suggestions:
Regear the truck so you can use 1st and don't wheeze out of air at rpms you don't need to be turning.
That's wasting fuel.
Get rid of the RPM intake and put a 500 cfm vacuum secondary carb on a regular Performer (or even the stock cast iron H.O. manifold)
Narrower ports create lower pressure and higher velocity.  This all equals better metering signal at lower rpms.
Use a cam with wider lobe centers to make more torque.

Power suggestions:
Revert to plan A. Stroke it and add aluminum heads.
But don't expect it to run too well on the street.
You will be leaving a lot  on the table if you choose 87 octane and 9:1 compression.

I think I'd be fine with the MPG you're getting with a stroker in my truck.

I may change out the rear gears to 3.55 or something like that, it currently has 4.10s in it and I know that isn't helping economy any. However I'm fairly certain that it has the oddball Dana 61, which seems to have very little aftermarket support/parts. Ugh.

How exactly will I be leaving a lot on the table with a 9:1 compression?

I'm not being snarky hah, I genuinely don't know. Is it just the bit of lost HP/TQ/efficiency?

As to keeping my foot out of the pedal, I'm sure I will be burning a lot of gas when I don't baby it, which is fine. It's more that I'd like to know I can get decent MPG if I wanted to if I wasn't gunning it all the time hah.

I think what is being said is that compression ratio helps a bunch with MPG due to the increase in power and efficiency as it goes up.  And aluminum heads allow you to run about 1 point more compression on the same gas as iron heads.  So running 9:1 compression is leaving a lot of efficiency on the table.

Gotcha.

Isn't the generally accepted calculation about a 3% or 4% increase in power for every full point of compression increase?

It seems to me that 3% or even 5% more power/efficiency may not be worth the extra cost of 93 octane when go I fill up.

If that's all I'm sacrificing I personally wouldn't mind.

But if a 9:1 to 10:1 compression bump netted me an average extra 1.5 MPG, that would probably make it worth it, to me anyway. But that's just a random number came up with. I'm not sure if it would increase MPG by any *noticeable* amount...?

You may be missing something.  The theory goes that if you can run 87 octane gas at 9:1 with iron heads you can still run 87 octane gas at 10:1 with aluminum heads.  And while that one point of compression might only give 3% more power, it is power that would be left on the table if you went with 9:1 and aluminum heads.

But, the one point more compression with aluminum heads to run the same octane fuel is not hard and fast.  It isn't 1.00000 and you can still run 87 octane.  It varies by engine configuration, cam duration and overlap, shape of the combustion chamber, thermostat, and even the flow path of the coolant.  IOW, I'm not saying it is a given that you can run 87 octane with aluminum heads and 10:1 compression.  I'm just trying to explain the theory.

Gary Lewis wrote

You may be missing something.  The theory goes that if you can run 87 octane gas at 9:1 with iron heads you can still run 87 octane gas at 10:1 with aluminum heads.  And while that one point of compression might only give 3% more power, it is power that would be left on the table if you went with 9:1 and aluminum heads.

But, the one point more compression with aluminum heads to run the same octane fuel is not hard and fast.  It isn't 1.00000 and you can still run 87 octane.  It varies by engine configuration, cam duration and overlap, shape of the combustion chamber, thermostat, and even the flow path of the coolant.  IOW, I'm not saying it is a given that you can run 87 octane with aluminum heads and 10:1 compression.  I'm just trying to explain the theory.

Correct, it also depends on your cam too and how much overlap you have.  more over lap and more compression you have to run to offset it.  A cam with more over lap you can actually get away with 87 octane regular with as much as 11:1 maybe even 11.5:1 with aluminum heads.

I set my goal at 9.5:1 as I wanted to be able to run 87 with aluminum heads and while sure one could run 10:1 my cam with the overlap actually recommends 8.75:1 to 10.0:1 and I figured 9.5:1 would be right in the middle to give me a little cushion for my 87 octane regular grade goal.

Ive actually seen a stroker get away with 87 octane with 12:1 compression with aluminum heads but it had a hot cam that didnt start to make power till around 3,000 rpm and had a lot of overlap.

On the chamber shape, the only way to go is the fast burn "heart shaped" chambers which helps reduce hot spots but it will require you to turn your advance down as Ford engines wont like more than 32* - 36* total mechanical timing with fast burn heads.  The quench is another, if you can get it around the 0.040" ideal quench it will also help you run lower octane fuel as well by helping to reduce hot spots in your cylinder.

Aluminum is a much better conductor of heat.
Heat IS horsepower.
While you can use aluminum heads to reduce detonation (if everything else is exactly the same) you're going to make less power because you'll be putting more heat into the coolant and less pushing on the crown of the piston.

Quench is very important in staving off detonation.
As Rusty said .040" is ideal and given that most common head gaskets are right around that thick (checking a compressed Fel-Pro I saw .039") you need to be zero decked.

If you intend to stroke your 351 you're probably better off at 408 because of the improved rod to stroke ratio.
While some may think the 393 is cheaper using 351 rods and 302 pistons, once you swap to a performance head -typically using a 2.02 intake valve- the machine work to deck the block, plus rod conditioning and better bolts you're money ahead with forged rods that come with better bolts and pistons that already have the right compression height and big enough pockets.

Rusty also pointed out that you can get away with more static compression using a cam with a lot of overlap.
But tighter lobe centers with lots of overlap make for low vacuum, and low dynamic compression at low RPM.
They also make for a lot of fuel charge going straight out the exhaust!
That is fine if you're only going to fire the car for long enough to get down the track but you're going to have a peaky engine with abysmal fuel mileage.

I'm sticking with "if you want a 400+ horsepower Windsor it isn't going to be civil and it isn't going to be economical"
You have to burn fuel to make heat, and you need heat to make horsepower.
There is no getting around the laws of thermodynamics or how inefficient 50 year old internal combustion engines are inherently.

From my perspective you are much better off making all the gains you can in VE and BSFC and getting rid of the short gears so your truck can stretch its legs.
I don't know how oddball a D61 is.
It seems only available in F-250 from '74-'82 and the 350 from '78-'85, according to Filthy Motorsports web page.
But they were specifically built with larger pinion offset to allow 3.00:1 and 3.07:1 R&P ratios.
Does your carrier have "61" cast into it? If it's a regular D60 you can get 3.54's for under $200.

I appreciate your input, thank you.

If I recall correctly the sticker on my door jamb indicated I had a Dana 70, but searching online for the code on the differential cover pointed to it being a Dana 61. So that's odd. "4.10" is also stamped on the metal plate the code is on. Changing gear ratio was in the plans regardless, I don't tow anything and 4:10s may be overkill with 32 or 33" tires.

To be honest I'm not sure if I should stroke it or not at this point hah. I'm not after a race truck or anything, just a peppy truck that's fun as a daily driver and doesn't make me go broke at the pump. I may have been too set on some HP number, but in reality for a street vehicle I suppose that's not as important.

If stroking it adds (a guess) 40 HP/50 lb ft of torque, but increases fuel consumption significantly, it may not be worth it. But if it only decreases my average MPG by 1 (again, a guess), then I'd say well why not?

My goal is to build this motor right (for me) the first time and not be thinking 6 months down the road "Oh dang I should've just built a 351 to save gas", or "Dang I should've stroked it with those 190cc 11R heads cause this truck's not quick enough". If you get what I'm saying ha.

Searching the web for truck motor builds is somewhat annoying, alot of the information/discussions I find are about guys building a 351/stroker for a Mustang or some other car which doesn't really apply to my wants/needs.

On a related note, is your 460 stock?

I think we all like the idea of a powerful engine that's fun to drive.
But the reality is we're driving 40 year old trucks that will never be an SVO Lightning or a diesel with 750 foot lbs of torque.
If you get to 400+ horsepower things start to break and you're going to have a hard time getting that power to the ground.

I'm not doubting that your truck is equipped with a D61. There's another member here in CT that has the semi floating version.
Just that 4.10's in a D61 seemed counterintuitive to me. (why would Dana build it when the much more common 60 was made for ratios like that?)
Maybe get under there with a wire brush and find the BOM stamped in the axle tube, the 61 cast into the center section or fully decode the tag you've already read?
Finding gears for a 61 may be more trouble or expense than swapping the whole axle?

Stroking your engine to increase power isn't a bad idea.
I still think if you're going to do that the longer rod found in a 4.000" stroke 408 will net more torque than the 5.956 rod found in a 351/393.

Only you know what's right for you.
"Peppy" seems to me that you want your truck to accelerate quicker.
"Quick" is not the same as "fast". It's down to defining your goals and how much you will spend to get there.

Nothing's going to change the fact that a F-350 is a big vehicle.
It's torque that turns the tires. That's what gets you out of the hole, and changing to lower numerical gears is going to have the opposite effect.... but it will help keep highway rpms down.
These trucks are not aerodynamic and since wind resistance goes up in square with speed if shorter gears mean you're driving faster you're going to burn more fuel.

This gets back to what Pete said about volumetric efficiency and my comment regarding brake specific fuel consumption.  Also see my comment about charge inertia with regard to your first question about runner volume.
If your intent is to run this engine at redline all the time bigger ports will have more absolute flow and make horsepower up there.
If you want a broad spread of torque that helps the truck accelerate you want the volumetric efficiency that comes with higher port velocity.

This 460 is fairly close to stock.
I lost a rod in the dead of winter 2008 and quickly swapped in a long block with a 'towing' cam and 'un-retarded' timing set because I needed the truck for work.
While I had another tight low mileage engine intended to build for my truck, it and the stand it was on got lost in the shuffle of moving to a new location.
I still have the parts (cam, heads, valves, rockers, double roller chain, oil pump, gaskets, etc) but I doubt I'll ever find another deal on a low mileage short block that hasn't been produced in 25 years.

I think every one of us is saying that how the components you choose work together is more important than any piece on its own.
Tuning is the icing on the cake. It can't make chocolate out of lemon.

Rusty is posting good information.
As I remember 'Conanski' a moderator over at FTE was pretty knowledgeable about Windsor builds as well, and often posted theoretical charts from one of his Dyno programs.
His info is also geared more towards trucks and less about drag cars.

Thats a big reason why I want to dyno my truck after I get the drivetrain completed.  I am very curious what my 302 makes power wise cause DD2000 claims it should make close to 400hp with the small tiny roller cam I picked out which goes hand in hand with Blueprint that has a cam slightly larger than the one I have with their in house non CNC ported aluminum heads and is rated at almost 400hp as well.

I honestly dont believe its going to be 400hp but I am curious cause that is two different sources indicating close to 400hp and I start to wonder if I low balled it too much with my 325 - 350 range.  Engine builder I know through work he said with aftermarket aluminum heads there is zero reason why you cant make 400hp.

I am also curious about fuel economy, since I am going with the Sniper Stealth I have more flexibility to lean the fuel mixture out at low load cruise to help improve fuel economy and I can enrich high load to help improve power production.

Still being a truck Id be happy if I can get between 15 - 18 mpg city and 18 - 20 mpg highway which would be a increase over my smog carbed 302 which with the ethanol blended fuels I am looking at 12 city and 15-16 highway.

Another reason to have your truck dyno'd is to get the ignition timing dialed in.  While the Sniper Stealth system can adjust timing, I don't think it knows what timing is best.  So having the truck tuned on a dyno will let the timing map be tweaked so you get max power and max economy w/o pinging or detonation.