347 'Power Build' Stats? [Archive]

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cv2065

07-05-2018, 08:58 PM

Instead of a 351W, was looking at possibly deciding on a 347 'Power Build' thats offered by a few of our forum's supporting builders. Any comments on what 347 you have and build/performance stats?

Papa

07-05-2018, 09:07 PM

I opted for Blueprint Engines based on a few factors:

1) Performance
2) Virtually plug & play with the FFR Roadster
3) Quality components in all aspects of the engine
4) Warranty (30 month - 50,000 miles from first start)

https://thefactoryfiveforum.com/attachment.php?attachmentid=84569&d=1524421786

My engine started on the very first turn of the key and it sounds and runs strong!

https://www.youtube.com/watch?v=doBle7rb7hI

CraigS

07-06-2018, 06:15 AM

I still think you are better off w/ a 351. you have the same displacement w/ all the stuff like rod angle and how far the piston drops out of the bottom of the bore being in the standard range. You also get all the larger rod, crank, and head bolts, nuts, oil pump drive shaft, etc., for free in the 351. From there an inexpensive upgrade is a 393 which uses a combination of stock type 351 and 302 rods and pistons (I forget which is which) w/ a stroker crank. Or go to 408 w/ all replacement crank, rods, and pistons. The 351 is a slightly larger engine which makes the left side rear plug a little more difficult to get to but that happens so infrequently it doesn't matter. I did a 408 winter of 2014-15 and haven't touched the plugs since.

mike223

07-06-2018, 06:24 AM

When you go to 347 off 302 the piston pin is up in the oil ring, and the rings are all as close as you can get them - Lots of people are running these.

393 can use stock 351 rods + stock 302 pistons (oem ring positions).

Many, many things to consider when going to a stroker crank.

edwardb

07-06-2018, 07:06 AM

Pistons, rings, rod angles, etc. etc. are all well established for the 347 and are completely reliable with the right parts. So much so that 363 is pretty common now with aftermarket blocks, which I'd recommend in any case. The larger crank and mains of the 351 block is actually considered a negative by some builders. For the RPM's and HP we're typically running here, almost for sure will never be a factor. But the point is either is a good choice. With pluses and minuses for each.

scottiec

07-06-2018, 08:11 AM

I had a 302, and I am currently building another one right now. If I was starting from scratch, I would be going with a 351w hands down. 351's have more meat, can handle more power, and are more forgiving. Yes, you need to consider air cleaner height, but that has been discussed here. If you watch Engine Masters, you will find an episode where they made some silly power with a stock 351w bottom end and threw some AFR heads with a small cam on it. I wan to say it was coming in around 480 hp. And trust me, the cam was nothing impressive.

There are also things that are less finicky about the 351. For example, 1/2 inch head bolts instead of 7/16th on the 302. From what I have read (and someone correct me if I'm wrong), but the deck of the 351 shows less distortion when being torqued due to the extra material. Does that mean the 302 is bad? Absolutely not. Ford put them in a bunch of stuff and they work great. This kind of stuff is just splitting whiskers.

I decided to stay with a 302 because I am on a budget the parts I currently have would transfer over. I didn't want to buy new headers, intake manifold, ect.

You will read an insane amount of information about rod angles, bore, etc when it comes to the 347. Just remember, there is more than one way to make 347 cubic inches. And remember, the car will be plenty fast with either one.

Jeff Kleiner

07-06-2018, 09:32 AM

cv2065

07-06-2018, 03:18 PM

Although to some degree their suggestions/opinions are contrary to one another I agree with points made by both Craig and edwardb. A 351 based engine is "easy" power without stressing it. They can make a great easy driving cruiser engine with a mild setup or get wilder with more displacement and more aggressive components. To me part of the appeal of the 347 is the RPM potential; the same larger journals that help strengthen the 351 based engine limit the safe RPM range due to bearing speeds---if you want something that you can really twist into the upper ranges a 347 will probably be a better candidate.

cv2065, I assume you realize that a 351 based engine requires different headers than a 347.

Jeff

Thanks everyone!

Hey Jeff. Yes sir, I know that's why I was quickly trying to throw around some last minute ideas, as Stewart 'may' be picking up my kit any day and FFR said they could make a change to 302 headers if I wanted to, but had to be soon.

So, reading a bit more, I think for my needs, I won't be typically twisting past 5K RPM, so looking for the low end torque to pull me back in my seat throughout the lower power band will keep me smiling. I think I'll keep my original thoughts and stay with the 408 stroker. I may even go Craig's route and just build it from the short block. Those Dart blocks are very tempting, but need to stay in budget!! AFR heads, Performer intake and a nice duration cam, and I'm in business!

Thanks again for everyone's thoughts on the topic....very helpful!

Jeff Kleiner

07-06-2018, 06:47 PM

Thanks everyone!

Hey Jeff. Yes sir, I know that's why I was quickly trying to throw around some last minute ideas, as Stewart 'may' be picking up my kit any day and FFR said they could make a change to 302 headers if I wanted to, but had to be soon.

So, reading a bit more, I think for my needs, I won't be typically twisting past 5K RPM, so looking for the low end torque to pull me back in my seat throughout the lower power band will keep me smiling. I think I'll keep my original thoughts and stay with the 408 stroker. I may even go Craig's route and just build it from the short block. Those Dart blocks are very tempting, but need to stay in budget!! AFR heads, Performer intake and a nice duration cam, and I'm in business!

Thanks again for everyone's thoughts on the topic....very helpful!

You should be very happy!

Jeff

scottiec

07-07-2018, 06:03 AM

Completely agreed

johnnybgoode

07-07-2018, 11:17 AM

cv2065

07-07-2018, 12:51 PM

Good choice, you won't be disappointed. My carb is a bit on the small size but motor makes great power from 1500-5500 RPM.

https://www.youtube.com/watch?v=Jao9vziGZl0&list=UUIYwIy3i7G81K1MWyTOJ-2A&index=20
https://www.youtube.com/watch?v=UgIOsRlho9g&index=18&list=UUIYwIy3i7G81K1MWyTOJ-2A
https://www.youtube.com/watch?v=Jao9vziGZl0&list=UUIYwIy3i7G81K1MWyTOJ-2A&index=20

Scott

Man that sounds great Scott!!

TexasAviator

07-08-2018, 09:34 PM

I think you will love the weight size and power a 347 makes. It does what a coyote makes and is in a smaller simpler package. Plenty strong and proven. Heck I built a 347 by myself. My build thread has my step by step build.

The engine was put on a dynomite sea and land unit that was built for boats and car engines. Bob has adapted the dyno to allow him to work on Cobra cars as well as his boat business. This is my engine sitting next to the supercharged big blocks he builds. Can you say 1000 horsepower!

https://farm5.staticflickr.com/4567/27025441399_1bda944a62_c.jpg (https://flic.kr/p/Hb9sbc)20171202_000642 (https://flic.kr/p/Hb9sbc) by Brandon Fertig (https://www.flickr.com/photos/158928436@N07/), on Flickr

Once on the dyno we pulled several runs to get the engine broke in and warmed up. We got it over 3000 rpm and heard a rocker arm. I had to go in and tighten one more rocker arm because it was overlooked on the attempt to correct earlier problems with my setup. We did a few more pulls but found one more hiccup. We had to fix another mistake of mine with the harmonic balancer vs the timing light. They were not in sync and we had to make new timing marks to find TDC and 0 degrees. Once bob corrected it he made pulls at 28, 30, and 32 degrees of timing at WOT. This is with his exhaust system which is essentially no mufflers. The car made the following power outputs.

Peak
hp/tq
450/460 @ 32 deg
470/440 @ 30 deg
474/439 @ 28 deg

We data logged and saved it at 28 degrees with an afr of 12 at wot. We could not believe it. High fives and laughter all around. We made over the 450 hp mark. I thought at one point it would only be 430 hp based on my fox body experience. I knew the crappy 5.0HO manifolds held people back but WOW.

Next we wanted to run my setup with stock ffr sidepipes. Bob welded in the bung and I got all the exhaust apart off the dyno runs we just made. I couldnt stop smiling. I mean this engine is making 475 hp! I would have never imagined it was possible with just 5900 rpm.

https://farm5.staticflickr.com/4579/27025438709_35790f277b_c.jpg (https://flic.kr/p/Hb9rnP)20171202_172531 (https://flic.kr/p/Hb9rnP) by Brandon Fertig (https://www.flickr.com/photos/158928436@N07/), on Flickr

Once we got the side pipes were installed it was time to see what it would do with how the car would be on the street.

The side pipes went in and we fired the dyno up. Here is a video of that. SELECT HD AND MAXIMIZE YOUR SCREEN TO WATCH THE HP.

https://www.youtube.com/watch?v=ymG-6RGR83Y

WATCH THE VIDEO OF THE BEST DYNO RUN OF THE NIGHT!

cv2065

07-08-2018, 10:47 PM

Nice videos TA! Your engine is a beast!! I built my last engine (383), but wanted to focus on the build this time and buy crate with a warranty of some kind. Although starting from a short block would speed things up, so maybe not off the table just yet, especially if I can get a decent deal, but we’ll see. I checked out TRE Performamce. Looks like a good outfit and they have some positive reviews, so thanks for the suggestion, I’ll keep them bookmarked. I’ll be going the 408 route and shooting for 500 lbs-ft of torque or better, which should be easy in a 351 block.

I see from your thread that you are getting ready to deploy. Safe travels Bud and we’ll see you when you get back!

TexasAviator

07-08-2018, 10:57 PM

Thank you,

You know many times I want to quit but when people ask why not. I ask them would you ever quit doing the one thing you know you born to do? I love flying and unfortunately it comes with a lot of time overseas. I am holding on for now but there will be a day I will have to say no more. Thanks for the kind words.

I have to also add that I thought I was going to want a 408, for the money I could have been there with the budget I had but with this 347 on the street I can bet you wont need any more power than this. I have had my car out a few times since I put the body on and I am scared to go more than 50 pecent throttle, i can smoke the tires through 4 gears, and the car pulls to the right under acceleration and I have to pull it back to center after ripping through the gears. I cant imagine this car with more power at this point. Its more than I ever imagined and I kept the weight down with the 302 based block.

mike223

07-09-2018, 06:44 AM

I have had my car out a few times since I put the body on and I am scared to go more than 50 pecent throttle, i can smoke the tires through 4 gears, and the car pulls to the right under acceleration and I have to pull it back to center after ripping through the gears. I cant imagine this car with more power at this point. Its more than I ever imagined and I kept the weight down with the 302 based block.

Once again - around / beyond 400hp / 400ftlbs - it becomes a question of how fast do want to go and still spin the tires?

How high a redline / revlimit do you want on the engine (how hard do you want to spin the engine), if you know you're already going to be in danger of breaking loose on a hard shift (@ 5k rpm)?

Things to consider...

GoDadGo

07-09-2018, 07:04 AM

Once again - around / beyond 400hp / 400ftlbs - it becomes a question of how fast do want to go and still spin the tires?

How high a redline / revlimit do you want on the engine (how hard do you want to spin the engine), if you know you're already going to be in danger of breaking loose on a hard shift (@ 5k rpm)?

Things to consider...

Mike223 made very valid points regarding when and where wheel spin comes in to play.

I was making someplace between 425-475 HP (Not Dynoed) before a block problem and life sidelined my project.
In "Go-Kart Mode" the car would go into wheel spin in 1st and 2nd gear at or about 1/2 to 2/3's throttle on NITTO-555's.
Another thing to consider is likely running Drag Radial to get some grip instead of a typical high-performance street tire.
555-R rears would likely have been a better choice for me instead of the standard 555's.

If you slow this video down to 1/2 speed you'll hear me pedal the car when I simply attempted to accelerate rolling into the throttle in 1st gear:

https://youtu.be/PCngiKoopkA

TexasAviator

07-09-2018, 07:44 AM

I too am running the nt555 315/35r17 and it doesn't care, it spins them. I redline at 5900 making that 475. It's a fun power band but I could have been content with less, so it will be a great cruise and smiles when I want to get into it. Mission accomplished.

cv2065

07-09-2018, 08:01 AM

Mike223 made very valid points regarding when and where wheel spin comes in to play.

I was making someplace between 425-475 HP (Not Dynoed) before a block problem and life sidelined my project.
In "Go-Kart Mode" the car would go into wheel spin in 1st and 2nd gear at or about 1/2 to 2/3's throttle on NITTO-555's.

I was running about the same HP/TQ with a 383 in my 67 Camaro. I could 'chirp' them in first and second at full throttle, and never felt a loss of control. I'm sure it had a lot to do with the weight of the car as well, as that car weighs in the neighborhood of 3,600lbs. I was thinking that the additional 100lbs on the 408 on the front end would help somewhat with control a bit.

skidd

07-09-2018, 08:11 AM

Thank you,
I have to also add that I thought I was going to want a 408, for the money I could have been there with the budget I had but with this 347 on the street I can bet you wont need any more power than this. I have had my car out a few times since I put the body on and I am scared to go more than 50 pecent throttle, i can smoke the tires through 4 gears, and the car pulls to the right under acceleration and I have to pull it back to center after ripping through the gears. I cant imagine this car with more power at this point. Its more than I ever imagined and I kept the weight down with the 302 based block.

The roads play a factor too. The roads here in San Antonio are brutal. I've never experienced a more slick surface anywhere. Turns out it has something to do with the amount of aggregate and lack of rubber they use in the mixture.. or so I've been told by my AutoX buddies.
I've driven high-power corvettes, vegas and mustangs on various roads in the Pacific North West (where I'm originally from). But, this little 300+hp 302 in my Mk4 with 315 Nittos and 3.55 gears, cant' maintain traction. 1/4 throttle ... 1/2 throttle... power-shift into 3rd... nothing but wheel spin. I too was a little worried about a 302 with a few go-fast parts was not going to be powerful enough.. turns out.. it's more enough for these roads. Every time I contemplate a 347 or 331 rebuild.. I ask my self "Why? so you can buy more tires sooner?". ;)

TexasAviator

07-09-2018, 08:15 AM

Well, whatever you choose there was a reason shelby decided on this amount of power and weight all those years ago. You have to recall the hp on the original big block 427 was heavier and made the same if not less than my 347. As mike223 said, anything more is just for grins and spins.

TexasAviator

07-09-2018, 08:18 AM

The roads play a factor too. The roads here in San Antonio are brutal. I've never experienced a more slick surface anywhere. Turns out it has something to do with the amount of aggregate and lack of rubber they use in the mixture.. or so I've been told by my AutoX buddies.
I've driven high-power corvettes, vegas and mustangs on various roads in the Pacific North West (where I'm originally from). But, this little 300+hp 302 in my Mk4 with 315 Nittos and 3.55 gears, cant' maintain traction. 1/4 throttle ... 1/2 throttle... power-shift into 3rd... nothing but wheel spin. I too was a little worried about a 302 with a few go-fast parts was not going to be powerful enough.. turns out.. it's more enough for these roads. Every time I contemplate a 347 or 331 rebuild.. I ask my self "Why? so you can buy more tires sooner?". ;)

Our roads do suck.
My sentiment exactly. I feel at the end of the day you have to be happy with whatever you choose as a powertrain. These cars also benefit from the t5z hearing and a 3.55 or 3.73 rear end. I think we are all saying the same thing.

Cv2065 you are going to love it no matter what you do.

mike223

07-09-2018, 08:19 AM

In "Go-Kart Mode" the car would go into wheel spin in 1st and 2nd gear at or about 1/2 to 2/3's throttle on NITTO-555's.
Another thing to consider is likely running Drag Radial to get some grip instead of a typical high-performance street tire.
555-R rears would likely have been a better choice for me instead of the standard 555's.

If you slow this video down to 1/2 speed you'll hear me pedal the car when I simply attempted to accelerate rolling into the throttle in 1st gear

But, this little 300+hp 302 in my Mk4 with 315 Nittos and 3.55 gears, cant' maintain traction. 1/4 throttle ... 1/2 throttle... power-shift into 3rd... nothing but wheel spin. I too was a little worried about a 302 with a few go-fast parts was not going to be powerful enough.. turns out.. it's more enough for these roads. Every time I contemplate a 347 or 331 rebuild.. I ask my self "Why? so you can buy more tires sooner?". ;)

And let me compliment you two on your valid points.

It's also certainly a question of individual comfort levels with buying + wearing out softer tires (what's your tire budget?).

I will freely admit that my comfort level ended at rolling into 1/2 to 2/3 throttle in 3rd gear and having the rear come out on me unexpectedly (in a straight pull).

So I changed from 3.55 rear gear to 3.18 rear gear and went to NT05 tires.

Back to comfortable.

TexasAviator

07-09-2018, 08:28 AM

So I changed from 3.55 rear gear to 3.18 rear gear and went to NT05 tires.

Back to comfortable.

What trans do you have?

I think the 3.73 is a bit much for my car. If I could do it again I would have done the 3.55 or less and as you said a softer tire.

scottiec

07-09-2018, 08:38 AM

For reference, I have 3.31's in the rear and really like them. And that was with a gt40p headed motor out of an explorer. All it had was a cam and converted to carb. I want to say 70 mph in 5th gear is like 2000 or 2200 rpm. chugga chugga chuga chuga

mike223

07-09-2018, 08:39 AM

What trans do you have?

T56 with 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.84:1 / 0.56:1

Would rather have the T56 with 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 (except I'm happy with 5th + 6th as above, would just prefer the taller 1st, 2nd + 3rd).

393W / 10.5:1 forged pistons / H beam rods / solid roller cam / TFS 170 heads, 750 DP ~ 460hp / 550ftlbs - brutal enough for me...

*Afterthought*

When I changed from 3.55 to 3.18, I also dropped my rev limiter from 6500 to 6000 - if you can still spin the tires at will, why spin the engine so hard? What good can possibly come from it?

GoDadGo

07-09-2018, 10:36 AM

For the record I'm one step right behind Mike223 with the following on the Dark Dart Side MK-4.

ZF S6-40 Trans > 2.68 1st / 1.80 2nd / 1.29 3rd / 1.00 4th / .75 5th / .50 6th / 3.73 Moser (Dana 44 Rear Sure Track) 3 Link Solid Axle

383 Dart (Chevy) 10.1 Forged Flat Tops / 6" H-Beams / Hydraulic Roller / Dart Iron Eagle 215's / Edelbrock 800 AVS / Team-G Single Plane!

A Nice 347 With The Right Rear End Gears Will Be Plenty Capable Of Putting Many Cars In Your Rear View Mirror!

mike223

07-09-2018, 01:31 PM

A Nice 347 With The Right Rear End Gears Will Be Plenty Capable Of Putting Many Cars In Your Rear View Mirror!

Pretty much anything without a 6 figure price tag and really good launch / traction control - even then you're not out because you've got 1000lbs minimum advantage on most of that stuff.

But better be wary of people who "bought" a fast car because many never bothered to learn car control - and that goes bad very quickly (faster than you can say "oops")...

GoDadGo

07-09-2018, 03:52 PM

But better be wary of people who "bought" a fast car because many never bothered to learn car control - and that goes bad very quickly (faster than you can say "oops")...

Especially Guys Driving Corvettes:

https://youtu.be/kzlg3oQMze4

The Silver One's Are Especially Dangerous So Beware!

mike223

07-09-2018, 05:06 PM

This GM EVP actually has pretty good racing experience.

Did not seem to help him much driving the pace car for the Detroit GP last month...

https://www.youtube.com/watch?v=A-rL-Bcd2Jg

Search youtube for leaving cars + coffee wrecks - It happens all the time with high powered stuff - Vipers, Corvettes, Cobras, etc.

Be careful out there.

TexasAviator

07-10-2018, 01:52 PM

The first video posted by godad...

The idiot on the right, lost traction and didnt let off the gas and recover. He kept it pegged and tried to keep racing. Fool

I watched that second video also...

It appears he unloaded the suspension from that bump and probably had some decel snap oversteer as well. There were no break lights and he tried to recover to the right turning front wheels but it was too little too late.

GoDadGo

07-10-2018, 02:07 PM

The first video posted by godad...

The idiot on the right, lost traction and didnt let off the gas and recover. He kept it pegged and tried to keep racing. Fool

I've advised Baby Go-Dad to never play with C-5 Corvettes at any red light.

If the C-5 driver only disengage the traction control, and not the stability system too, then the car can grab a brake or two in an attempt to straighten it out. It usually causes guys to spin out of control which "May" have contributed to the C-5 turning into the C-6.

Below is the Official GM video for the C-5's stability system:

https://youtu.be/LWNR-tvvwFo

TexasAviator

07-10-2018, 02:48 PM

Agreed, I think that is also why you see mustangs wrecking so much. The ford stuff is messing with the driver, who in turn tries to correct the cars logic. In the air force we call this pilot induced oscillation aka PIO.

The other part to that corvette race video is after he lost control he was still gaining on the other guy so my guess is he was still gassing it.