mjr46

from what I gather on your build your just looking for a build that is reliable with an average power output correct??...if so your 302 build will suffice

MBDiagMan

Thanks for the response. Building the same engine with a 3.4 instead of a 3.0 stroke will add about 60 fl. lbs of torque from idle to about 3,000 RPM and flatten the torque band in that area. The torque will not fall below the peak torque of the 302 until 4,000 RPM. Adding displacement with stroke adds LOTS of bottom end torque. You are not only adding the displacement, but you are also gaining leverage on the crankshaft arm.

The engine I propose will produce the same peak horsepower as an identically built 302 with the horsepower peak being at about 4,000 RPM as opposed to 4,500 for the 302. The 15% to 20% increase in off idle to 4,000 RPM torque is what I'm after.

The cost of building the 347 as opposed to rebuilding the 302 is not that great since in rebuilding the 302, all the same machining costs will apply PLUS I would have to buy pistons and turn the crankshaft for the 302 rebuild while these costs are part of the rotating assembly price.

The difference will be somewhere in the area of about $600 extra for the stroker. Remember, for this application forged pistons and crank are not necessary. Cast crank, Hypereutectic pistons and street duty rods are inexpensive compared to what I would need to build a 600 horse screamer.

I am doing my powerband research with Desktop Dyno. I know that it won't be absolutely correct, but I do believe that it gives very good information when it comes to comparing various engine component scenarios.

Thanks again for the responses. Keep 'em comin'.

mjr46

^^^^desk top dyno's are okay to give you an idea of different builds but your head, cam and intake combo will be key.....using your 302 parts on the 347 will give less than desirable real life power and often add to dissapointment like only a 25-40 rwhp difference.....a stroker needs to breath and powerband will be based on the cam you choose....if I were you I'd call a custom cam grinder such as : www.camshaftinnovations.com and have a custom cam ground based on your desires

MBDiagMan

LIKE I SAID, I am NOT looking for horsepower. I am looking for LOW SPEED TORQUE. A big inch, long stroke engine at low speed does not need big valves, big ports, big intake, big carburetors and big cams! In fact most of these things will hurt low speed torque.

I have already done my cam grind research and have selected it. The 252H gives me the maximum in off idle torque in combination with the other pieces that I'm using. Adding more cam will only raise the torque a LITTLE at an engine speed ABOVE where I am looking for the torque, but it will be at the expense of off idle torque which is what I want.

Peak horsepower will be THE SAME as a 302, albeit at a lower RPM. The torque on the other hand, will be about 50 more foot/lbs. from idle up to about 3,000 RPM. If I could get small tube, full length headers for this chassis, I could get almost as much off idle torque from a 302 as I will from this near stock exhaust 347. For that matter, if I could add small, long tube headers to the 347 I could twist the driveshaft in half. Since I can't get the headers and don't have the equipment to make them, I have to settle for the stroke to up the off idle torque where I want it.

There are LOTS of people who do not understand the difference between torque and horsepower or the relationship between the two. Torque is twisting power, horsepower is work over time. Horsepower is actually not a measured unit. Horsepower is calculated based on torque and speed.

SOoo... If I wanted lots of horsepower, I wouldn't need the stroker. I could use heads, cam and intake to get a gazillion horsepower out of the little 302. Anyone that has ever messed with one knows that. I want OFF IDLE TORQUE.

Let me try explaining this in different terms, terms that a Mustang guy might understand: I bought a late 85, five speed Mustang GT new. This was the last year of the Holley and the first year of the roller cam and tubing headers. Two years ago I bought an 06 five speed Mustang GT. The 85 had 210 HP and I don't know the torque figure. The 06 has 300 HP and although I don't know the torque figure, I think the torque peak is at about 4500 RPM. I think the 85 had a similar amount of torque, but it peaked at about 3200 RPM. The 85 was probably 10% lighter but had 3.08 gears as opposed to the 3.55's in my 06. BTW, both of these cars were bone stock.

All that explained, I could blind fold someone and give them a spirited ride in both cars. That person would most likely tell me that the 85 was considerably faster, but we both know that the 06 would outrun the 85 in a drag race. The 06 wouldn't only outrun the 85, but it would EMBARASS the 85.

THAT is the difference between low speed torque and high RPM horsepower. AGAIN, horsepower wins races while torque makes a car fun to drive.

FuzzyDiceRule

amen to that last statement, but like MJR is saying, a 347 with 302 stuff isnt going to be an amazing improvement over a 302 with those same parts, for what you are describing, a 302 with a good Heads, cam, and intake would be almost perfect for your needs

but either way you go, you arent going to have a problem with lack of torque

mjr46

........WOW WHERE do I begin .the only thing that I really take issue with is your lack of respect and condesceding attitude with the above statement towards MUSTANG OWNERS....all the rest of the BS ABOVE is pointless to discuss....just remember where you are and who came where looking for advice....I just never understand why people come on here from all walks of the world and love to trample mustang owners under their feet and act as if they are better.... LOL ..TO EACH HIS OWN........FYI I can do the same thing you desire to achieve with a 289/302 ..infact I have....got one whose torque far exceeds hp......LOL but it appears if I share my secret build it may condtridict your trust desktop.....anyway good luck with the build, may you achieve your goal

MBDiagMan

WOW!!! DID YOU NOT READ WHAT I WROTE???

I am a MUSTANG OWNER. I've not been without a Mustang since about 1975. I am a MUSTANG LOVER!!!!

I did not mean to imply that Mustang owners were incapable of understanding what I had written. I was trying to put it in terms that folks who have been around Mustangs could easily relate to. If I sounded condescending in any way then I apologize.

I find the Desktop Dyno to be a very interesting thing to play with, but I have enough street engine building experience to know that it is not lying to me.

When you use small runners, short cam and a long stroke, you WILL build LOTS of low speed torque. I've built small inch engines that made so much low torque that people didn't believe me when I told them the engine size. I also know that had they had a longer stroke, they would have made even MORE low speed torque.

BTW, I am QUITE aware of the decieving amount of torque that can be made with a 289 or 302. I just want more to haul around this big car.

I guess since you have such valuable "secrets" regarding engine building, you must have stumbled across some changes in the laws of physics. Congratulations and best of luck to you as well.

BTW, most engines maximum torque exceeds their horsepower. Maybe that was one of the new laws of physics that you discovered.

mjr46

nope..but carry on

MBDiagMan

If I had it to do over again I would have posted a simple question asking if anyone had any oil control experience with 355 pistons. Since I am a chatty sort, I put too much information in the post and it evidently led to my offending some of you.

Thanks very much for the responses and the sharing of your experience.


I offer my most humble and sincere apologies. I hope that we can shake hands and go away friends.

mjr46

^^^no one is offended...continue your thread....most on this sight are concerned with HP and ET in the 1/4 me on the other hand have 3 seperate mustangs with three seperate builds to satisfy three seperate intrests.....my 85 is for pure raw power and et......my 92 is for just that day I wanna cruise around with the power of the v-8 and my 66 is for the day I want to get all the looks and the slam me in the seat torque feel as it is faster than the 92 but slower than the 85 by a mile.........I understand your goal and if it were me I'd do the 347 bottom end and a mild RV type powerband cam maybe a 268h but the 252 will work and an edelbrock aluminum head with a 1.90/1.60 valve and a dual plane intake, you'll still have the low end grunt and a 3.50 gear maybe...but that's just me........my 66 has a similar build but with a chevy valve set up of 1.94/ 1.50 and has tons of low end to mid and with a 5 speed tranny cruise rpm's are 1900 @ 65 mph.....it actually could stand for more gear but I figure just leave it at that for mpg.........in fact I just threw the build together on the 66 with no intention of it being a power producer and it suprised me in the end.....and it out powers alot of better build 302's my friends have and it has cast iron heads......so Idon't totally disagree with what you have posted