347 Design Review

[bravenrace]

Okay, I've designed my 347 using my Engine Analyzer program along with other research and some harsh realities. I've bought some parts and have some yet to buy. The parts I already have are pretty much carved in stone, so no changes are going to be made there, but the parts that I have picked out and not yet purchased are open for discussion, along with any building tips and tricks.
First, this is for my '65 Mustang with a T-5 and a 3.80 trac loc rear with 27" tall tires. While my priority is open track use, the reality is that it will get a lot more street miles than track. I've built many engines in the past, but it's been decades since I've built a SBF, so any suggestions specific to this engine are appreciated. I don't really need to know generalities of engine building. Been there, done that.
Okay, the engine. This is what I have so far:

- '87 5.0 block machined for 347
- Eagle balanced rotating assembly with cast crank, I-beam rods and forged pistons with standard valve reliefs
- Crane 1.6 ratio roller rockers
- Edelbrock Air Gap manifold
- Hedman Elite headers and Magnaflow 2.5" exhaust.

The items above are pretty much written into stone at this point, save the rocker and maybe the intake. Heads, cam, carb, ignition are all open. My plan, based on the program and research, was originally to use AFR 165 heads and a Comp XE274HR cam, which seemed to work the best on the program and was also the recommendation that Comp made. The carb is a Holley 650 double pumper.
Now, here's the thing. Trick Flow is headquartered in my home town and I know some of the guys there. So instead of the above combo I've decided to use TFS track heat 170 heads with 58cc chambers and a TFS stage 2 cam. This combo only gives up very little to the AFR-CC combo and is about $600 cheaper. And I get to support a local company. The one down side is that to use the TFS heads, I'll want to return my standard pistons and get the pistons with the correct valve reliefs, but that's not a big problem.
On the computer this combination provides 420hp@6000RPM/405lb-ft@4500RPM, and 300hp/364lb-ft averages from 2000-6500RPM. This is at SAE standard conditions, not dyno standards. By replacing the intake rockers with 1.7 ratio, these numbers are within a tick of what I got with the original combination.
If these numbers are reasonably accurate, then this is plenty of power for me, but I want to run this by you guys anyway. So, what say you?

 

[Fst Blk]

I think whatever program your using is wrong when comparing the 165 AFR's and the 170 Trick Flows. With the shorter runner and twisted chamber of the twisted wedge they are closer in MCA to the 185 AFR's. I prefer the twisted wedge stuff myself.

Bill

 

[68EFIvert]

I am also a fan of the TW stuff. I have the 190 FAC heads on my car and they seem to work great. Have you considered a custom cam for your combo? May be worth the look.

 

[bravenrace]

My program is known to be one of the most accurate out there, but who knows. Do you guys have any direct comparison that convinced you that the TFS was better? If so, I'd like to hear it. I also added published flow data to the canned heads, so while the numbers may or may not be dead on, the comparison should be fairly valid. That's neither here nor there though, since I'm using the TFS heads anyway.
Yes, I considered a custom cam, but after discussing it with the engineers at both Comp Cams and TFS, they both recommended off the shelf cams. But if you have specs on a custom cam that has worked well for you, I'll consider it and have no problem plugging it into the program to see how it compares.
I should add that my intention throughout this project has been to build a good all around performer, so my design does sacrifice some peak power to maintain sufficient low end torque.

 

[Legallyfast]

Sometimes the extra money for custome cams is overated. Like where u can save $600, i say go for it. AFR heads are nice, but does it really matter to you? I know i would love to get those heads too, but really cant complain about my edelbrock heads. Make good power. Now there are time where i would say get the custom cam, like when u r racing in a class and there are rules u have to play by. By all means then. But for a dd, occassional strip, ots works.

 

[68EFIvert]

My specs for a custom cam won't work for your build. I have a blower and numerous other mods that make our situations very different. I did a lot of research before building my current engine and I found a great place to bounce ideas off was on http://sbftech.com/. Very knowledgeable people and the site has some great threads. OTS cams will work fine for a general cruiser but I found for the modest increase in price you will get a camshaft that is specific to your car and objectives. I had purchased a TFS Stage 2 cam for my car and some Edelbrock Victor Jr heads and then sold them at a loss to get my current setup. My first engine had AFR 165's and I sold them as well.

 

[Jonk67]

Just curious why you chose the heavier forged pistons for a stroked engine that would benefit from lighter pistons? Forged seemed to be the requirement for forced induction but not necessary for NA, if you plan to FI later, then it makes sense.
Jon

 

[bravenrace]

Just curious why you chose the heavier forged pistons for a stroked engine that would benefit from lighter pistons? Forged seemed to be the requirement for forced induction but not necessary for NA, if you plan to FI later, then it makes sense.
Jon

Well, a couple reasons. One is because I wanted the option of adding a power adder later. Second, I've had name brand forged pistons fail on a n/a engine, so going to cast wasn't an option I even considered. Third, I've never built a performance engine without forged pistons, so whether it makes sense or not, that's me. And IIRC, the weight of the pistons isn't significantly more than the hypers that were in the Eagle kit.

 

[S8NS 289]

for a driver -Personally, I'd get the best deal i could on a set of heads.

Then you can use the money saved for the nickel and dime stuff.

600$ is alot of saved money to me....

 

[Legallyfast]

Give you an idea. Most of a stock late model stuff is strong enough. For examle with a good tune supercharged I made 400 rwhp, 9 #s of boost. All bolt-ons. Steeda #18 cam, gt-40 tubular intake with a ported lower, edelbrock small valve heads 1.90/1.60, vortech S trim, power pipe, 42# injectors, 90mm maf and shorty headers, off road h pipe and flowmasters. Had to stop due to a fuel leak and my tuner said there was likely 50 hp still to come because he had not even pulled timing yet. The engine is ok to 500 at the wheels then they tend to split. And that number is a variable. So I would not spend extra money on rods and what not. Honestly, i wouldnt do a stroker if you are going to do a power adder, unless you are planning to use an aftermarket block, then of course I would do everything at that point. It really is not that hard and there is a huge price difference between the two. I am going to limit myself for now, then later get the aftermarket setup

 

[buckeyedemon]

Just curious why you chose the heavier forged pistons for a stroked engine that would benefit from lighter pistons? Forged seemed to be the requirement for forced induction but not necessary for NA, if you plan to FI later, then it makes sense.
Jon

SRP lists a forged 4032 aluminum, 4.03", flat top, 1.1" ch piston at 395 grams.

do you have a part number for a similar non forged piston with weight? i'm curious to see how might lighter a non-forged piston is.

 

[dm289]

I would save the $600 and get the TF combo... remember the ride in mine with only a 260 Comp Cam, Thermactor Bumps and exhaust manifolds... I broke loose flooring it in 2nd in front of Summit... either combo will kick a**...

 

[Jonk67]

SRP lists a forged 4032 aluminum, 4.03", flat top, 1.1" ch piston at 395 grams.

do you have a part number for a similar non forged piston with weight? i'm curious to see how might lighter a non-forged piston is.

I don't see any of the SRP pistons coming in at 395g,
http://www.jepistons.com/Catalogs/SRP/F ... t_top.aspx
the 347 piston is 423g + ? wt. pin (they don't list pin wt. that I can find but assume it would be heavier than a hyper pin?) A similar sized hyper would be 415g + 102g pin. SRP only makes forged so can't really compare equally.

You're looking at 8 -10 grams heavier per piston between forged/hyper, doesn't sound like much but it is more and a stroker moves this wt. a farther distance, it all equals HP. I was just curious and the OP stated his reasons to use but i think he meant that a hyper piston failed previously instead of a forged failing?
Jon

 

[buckeyedemon]

I don't see any of the SRP pistons coming in at 395g,
http://www.jepistons.com/Catalogs/SRP/F ... t_top.aspx
the 347 piston is 423g + ? wt. pin (they don't list pin wt. that I can find but assume it would be heavier than a hyper pin?) A similar sized hyper would be 415g + 102g pin. SRP only makes forged so can't really compare equally.

You're looking at 8 -10 grams heavier per piston between forged/hyper, doesn't sound like much but it is more and a stroker moves this wt. a farther distance, it all equals HP. I was just curious and the OP stated his reasons to use but i think he meant that a hyper piston failed previously instead of a forged failing?
Jon

http://www.jepistons.com/Catalogs/SRPPRO/Ford/flat_top-pro.aspx

why would a pin for a forged piston be heavier than a cast piston? i missed where you posted a part number and weight of a similar cast piston. please post a link, part number or weight.

thanks.

 

[Jonk67]

I didn't look at the prof. series page for SRP, look like that's where they have the lightest ones. The hyper example I pulled up was a KB piston:
http://www.summitracing.com/parts/uem-s ... /make/ford
The SRP prof. series is $700/set vs. the hyper $380/set, but cost wasn't mentioned as factor. I didn't look for a prof. series hyper piston for wt.
Do you use the same material pin for a hyper and forged?
Jon

 

[bravenrace]

I don't see any of the SRP pistons coming in at 395g,
http://www.jepistons.com/Catalogs/SRP/F ... t_top.aspx
the 347 piston is 423g + ? wt. pin (they don't list pin wt. that I can find but assume it would be heavier than a hyper pin?) A similar sized hyper would be 415g + 102g pin. SRP only makes forged so can't really compare equally.

You're looking at 8 -10 grams heavier per piston between forged/hyper, doesn't sound like much but it is more and a stroker moves this wt. a farther distance, it all equals HP. I was just curious and the OP stated his reasons to use but i think he meant that a hyper piston failed previously instead of a forged failing?
Jon

No, I meant forged.

 

[Jonk67]

Ok, just seemed odd to read you've had forged fail before so you're going with forged :shrug
Was the line of thought that if forged have failed then hypers would fail worse? Or sooner/more likely to fail as they are inferior to forged?

I agree with the forged for the option of a power adder, but I've also read that a power adder with a stroked and stock block is questionable. I didn't read more into it as I didn't have any plan to do a PA to my stroker.
Jon

 

[Horseplay]

Invest the time it takes to make a phone call to Woody at FordStrokers.com. 1 (877)723-5487

All he builds are SBF stroker engines. Has been doing it this way for years. He's a good guy and will be happy to answer your questions and give you some advice. He pushes Trick Flow heads and has his own special set-ups. He does all his own machining in house as well. Simply, he is the best at building the type of engine you are after.

fordstrokers.com

 

[buckeyedemon]

I didn't look at the prof. series page for SRP, look like that's where they have the lightest ones. The hyper example I pulled up was a KB piston:
http://www.summitracing.com/parts/uem-s ... /make/ford

Do you use the same material pin for a hyper and forged?
Jon

I wouldn't think a pin would be cast in either case but i really don't know.

The pin for the SRP piston I indicated is listed as 106 g for a total weight of 501 g. Versus your indicated cast piston of 517 g. Also the ring thickness on the SRP is smaller than your example, so the rings will probably weigh a few grams less.

So if you really believe 8 grams makes a difference (I don't believe it does in terms of HP, and I believe it's marginal for a street engine in terms of connecting rod stress. and yes I have calculated the force on a connecting rod at various piston acceleration rates), then it seems the cast pistons are on the wrong side of the fence.

Do you have any other links for lighter versions of cast pistons to illustrate your statement that forged pistons are heavier for the 347 application?

 

[bravenrace]

Ok, just seemed odd to read you've had forged fail before so you're going with forged :shrug
Was the line of thought that if forged have failed then hypers would fail worse? Or sooner/more likely to fail as they are inferior to forged?

I agree with the forged for the option of a power adder, but I've also read that a power adder with a stroked and stock block is questionable. I didn't read more into it as I didn't have any plan to do a PA to my stroker.
Jon

I've had name brand forged pistons fail on my in a n/a engine. One, a TRW forged piston, failed after very few miles when a ring land collapsed. In consideration of that, why would I go with anything lesser? Correct me if I'm wrong, but everything else being equal, is there any question about forged being stronger than cast? Is there anything stronger than forged? That's why I went with forged.
I have yet to find any evidence that forged pistons are significantly heavier than cast. I'm not saying your're wrong, I just can't find anything that is an apples to apples comparison. Another factor in my decision was my machinist, a guy who builds diesel truck engines at work and Ford race engines at home. He has had bad experiences with hyper pistons and suggested I go forged, at least with this particular kit and the components it included. I don't remember what the cast pistons were, but my pistons are Mahle forged, and that gave me a higher comfort level (for not a lot of extra money) over the off brand cast pistons in their other kit.
So unless there actually is a weight issue between them, I can't see any reason not to go forged, can you?