Trick Flow 170cc heads too small for a 393?

[Rusty_S85]

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

[SubSonic]

These guys have some 170cc 11R heads with an option for 53cc or 63cc combustion chamber sizes:

http://fordstrokers.com/induction/trick-flow-cylinder-heads/trick-flow-twisted-wedge-170-track-heat-11R

Is that $1540 price tag for 1 or 2 heads?

In my playing with CR calculators, 63cc heads don't get you down to 9:1 in any of the stroker packages I looked at. You could do it, as there are may thicknesses of head gaskets available, but then you will be sacrificing quench, which basically equates to hp/torque.

 

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.

[SubSonic]

Like Pete said above there's a whole lot of calculus to be done when juggling chamber volume, pistons, deck height, quench, rod ratio, cam overlap and timing, (which affects dynamic compression) port velocity and volume, etc...

Maybe he has better advice to offer since he has been looking at the same metrics as you?

Simulations are getting better and better.

Have you plugged all these numbers (plus gear ratios, truck weight, tire size etc...) into Desktop Dyno or something like that?

My brain just has a hard time putting 15mpg, 87 octane together with 400+ horsepower & Tq @ 5,500 rpm, and a 351 in a 1980's pickup.

I think runner volume is the least of your issues and would definitely be comparing cross section with that of your Performer RPM intake and whichever valve size you go with

.

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.

[Rusty_S85]

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.

[SubSonic]

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?

[Rusty_S85]

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

[Pete Whitstone]

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.

[Pete Whitstone]

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.

[Pete Whitstone]

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.

 

[ArdWrknTrk]

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?

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.