Trick Flow 170cc heads too small for a 393?

[ArdWrknTrk]

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.

I have been looking at 351W based stroker kits as well. Like you, I would like to build a motor than can run on 87 octane. The problem with all that I have found is that, if you buy the entire rotating mass (crank, rods, pistons), the kits all land around 10:1.

If you want to go shopping for pistons separately, you will pay more in the end, and you have to juggle a lot of math to make sure the pin height and quench height both come in where you want. Not to mention concerns about getting other dimensions and parts right - pin size, getting the right ring package, how much was shaved from the deck when the block was machined (many machine shops don't seem to keep track of that for you, or supply you with a final deck height number). Unless you are an experienced engine builder, some of that stuff can be pretty daunting.

Another hurdle is, if you are buying aluminum heads, the less expensive ones tend to have the smaller chamber sizes (58-62cc). You have to shell out about twice as much to get into the ones that have the 70-ish cc chamber sizes, and guess what, they're mostly on backorder status.

I'd be interested to see what you can come up with that allows a 9:1 compression ratio and still has good quench and rod ratio.

I'm almost at the point where I'm willing to buy off on running 93 octane. I work from home, have other cars to drive, and probably only put about 3000 miles a year on the truck, if that. At 12mpg and about an 80 cent upcharge for the premium gas, I'm only going to spend about 200 more per year on gas. Contrast that with spending more than a thousand for larger chamber heads, and it does not seem all that significant.

On the upside of that though, higher compression yields higher torque, which is what I want in my truck.

If you have aluminum heads there's no reason to limit yourself to 9:1.

Where do you live that premium is that much more expensive?

Around here (southern CT) 91 R+M/2 is $.10-.15 over 89.

Some stations still have 93, but it's not a popular option.

[mat in tn]

If you have aluminum heads there's no reason to limit yourself to 9:1.

Where do you live that premium is that much more expensive?

Around here (southern CT) 91 R+M/2 is $.10-.15 over 89.

Some stations still have 93, but it's not a popular option.

is CT. really big enough to have a northern / southern?

[ArdWrknTrk]

is CT. really big enough to have a northern / southern?

I'm in the "toe"...

There's definitely a huge difference between being 25 mi from Manhattan and the rolling farmland in the Litchfield hills.

[Pete Whitstone]

Where do you live that premium is that much more expensive?

Around here (southern CT) 91 R+M/2 is $.10-.15 over 89.

Some stations still have 93, but it's not a popular option.

I'm in north Texas, just north of Dallas. The prices today at the local RaceTrac (high volume gas stations down here) are:

Regular (87): $3.60

Midgrade (89): $3.85

Premium (93): $4.15

At least, that's what's posted on their website, I'm not certain those numbers are up to date, I seem to recall more like $4.59 for premium last time we filled up the wife's car. Regardless, I guess the span is only about $0.55, if those prices are accurate. Which makes an even better argument for going with a higher CR.

Of course, if gas prices go up, which I think is a fairly safe bet for the next couple years at least, that span might also go up.

 

[SubSonic]

If you have aluminum heads there's no reason to limit yourself to 9:1.

Where do you live that premium is that much more expensive?

Around here (southern CT) 91 R+M/2 is $.10-.15 over 89.

Some stations still have 93, but it's not a popular option.

Is 9:1 about the highest I can go with 87?

I do not have other cars to drive, nor do I want any. Honestly I don't like cars at all, and the new/used truck prices are crazy. Plus newer vehicles have no character. I realize most people buy older vehicles as projects/toys and have other vehicles with good mileage and whatnot. I'm not really interested in most modern cars.

What I'm saying is, I'd really prefer not to have to fill up with 93. I could probably be convinced to go with 89 hah. Around here that's the mid-grade. The $.50 a gallon will add up.

I figured 9:1 would be about the safe maximum in a hot/humid climate.

Besides a few horses/torque, what else would I be losing?

[SubSonic]

Is 9:1 about the highest I can go with 87?

I do not have other cars to drive, nor do I want any. Honestly I don't like cars at all, and the new/used truck prices are crazy. Plus newer vehicles have no character. I realize most people buy older vehicles as projects/toys and have other vehicles with good mileage and whatnot. I'm not really interested in most modern cars.

What I'm saying is, I'd really prefer not to have to fill up with 93. I could probably be convinced to go with 89 hah. Around here that's the mid-grade. The $.50 a gallon will add up.

I figured 9:1 would be about the safe maximum in a hot/humid climate.

Besides a few horses/torque, what else would I be losing?

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

 

[ArdWrknTrk]

Where do you live that premium is that much more expensive?

Around here (southern CT) 91 R+M/2 is $.10-.15 over 89.

Some stations still have 93, but it's not a popular option.

I'm in north Texas, just north of Dallas. The prices today at the local RaceTrac (high volume gas stations down here) are:

Regular (87): $3.60

Midgrade (89): $3.85

Premium (93): $4.15

At least, that's what's posted on their website, I'm not certain those numbers are up to date, I seem to recall more like $4.59 for premium last time we filled up the wife's car. Regardless, I guess the span is only about $0.55, if those prices are accurate. Which makes an even better argument for going with a higher CR.

Of course, if gas prices go up, which I think is a fairly safe bet for the next couple years at least, that span might also go up.

Filled up at Forbes with 93 this evening @ 3.99 9/10 (shrug)

Not sure why gas is more expensive in Texas.

We don't have any wells or refineries here.

[ArdWrknTrk]

Is 9:1 about the highest I can go with 87?

I do not have other cars to drive, nor do I want any. Honestly I don't like cars at all, and the new/used truck prices are crazy. Plus newer vehicles have no character. I realize most people buy older vehicles as projects/toys and have other vehicles with good mileage and whatnot. I'm not really interested in most modern cars.

What I'm saying is, I'd really prefer not to have to fill up with 93. I could probably be convinced to go with 89 hah. Around here that's the mid-grade. The $.50 a gallon will add up.

I figured 9:1 would be about the safe maximum in a hot/humid climate.

Besides a few horses/torque, what else would I be losing?

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

.

 

[Pete Whitstone]

Is 9:1 about the highest I can go with 87?

As a very very general rule, that would be about right. But there are so many different factors that go into it, it's impossible to say. I think the later EEC trucks had a knock sensor in one of the freeze plugs, so if you went with a system like that, you could push it a bit as you will have a safety net built in.

Other things off the top of my head that affect how much static CR you can have (I'm sure this list has many items missing):

- Valve overlap

- Rod ratio

- Ignition timing

- Altitude

- Temperature

- Chamber design

- Quench height

- Vehicle weight and towing requirements

Heck even things like spark plug heat range and ring sealing can have a minor effect.

I have to agree with ArdWrknTrk, your stated goals may be a bit optimistic. Realistically for a 351w, I think you could shoot for and achieve 350hp and 12-13mpg on 87 octane in a lighter SWB bullnose truck.

[Pete Whitstone]

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.