as i look more and more into a 347 im wondering what is there usally power out put if everything but the block is forged with my GT40 iron heads, cobra intake and a trickflow stage 2 cam? im aimin for a 400-500rwhp number and i dont think thatll do it alone but i wanna see were it could land me
avereage HP from a 347?
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TrueBlue95GT
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with GT40's on a 347, your looking at 300rwhp. You need at least twisted wedges or afr165's and even that's not the most optimum head. Also, the cobra is too restrictive of an intake for a 347. At least a Performer RPM or a Street Heat intake if not the RPMII or Trick flow R manifolds.
The general rule of thumb is 1hp per cube, and that is typically flywheel HP. Despite what I'm sure people will say in this thread shortly, it is NOT easy to get 400rwhp out of a 347, and it will NOT happen NA with GT40's. With some boost there's a good chance, but not NA.
bubba-dough
Active Member
I'd say with what you mentioned above you are looking at about 300 rwhp as long as you have all the other things like throttle body, injectors and so on. I put down 366 hp/ 393 torque on the wheels n/a with 11:1 compression (CHP 347) with a ported Explorer upper and lower intake which flows about like a Cobra, they have the same lower. It isn't quite like some aftermarkets but if you are on a budget the money saved is nice. 
sonicblue87lx
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- Jul 1, 2005
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Im puttin 310rwhp and 380rwtq with my 347
Another buddy of mine is puttin 350/350 to the wheels with his 347
Another buddy of mine is puttin 350/350 to the wheels with his 347
95Vert
New Member
If all you want is 400-500 get a SC, if you want more, get a turbo and you can get into the 700 range.
ljinx23
New Member
well, I am def. interested in this thread, because I just rebuilt the bottom end of the motor w/a 347 kit, but still have my AFR165s, track heat intake, and e-303 cam. 24lb. inj, maf, etc....what am i looking at? I know this is hard to estimate because there are so many factors, but i'm looking for a ballpark. thanks guys,
Lenny
Lenny
Lenny I'd guess you'll make somewhere between 325 to 340rwhp, but your torque will be way up there... I wouldn't be surprised to see it hit 370-380rwtq. This is a COMPLETE guess though. I will bet money that it will be a BLAST to drive on the street!
bubba-dough
Active Member
Killercanary said:
Actually Paul, between your post above, and this one (mine) there were not many to disagree. I too thought 400 to the wheels was the norm with a 347 about a year ago.. The more I have been reading these threads here and other forums, the more I think how hard indeed that is. This is where the "right combo" comes into play.. You can get anywere between low 300's and low 400's (100Hp difference) depending on the combo.
I cant wait to see what Vib gets when he's done...with the long tubes and 3" exhaust, etc. He should def. be in the high 300's.
Also SVT94Cobra, you can get a "decent" power load, then combine it with some traction mods, and you have a great all around street car, not just power. You can also look into getting a lower compression block and slapping some nitrous on there.
One more thing...
you said
. You dont need to spend the extra few hundred $$ to have a forged crank. You can get a cast crank, and just get the forged pistons, rods, etc.
GL!
RC
95Vert
New Member
95Vert said:
Yes, you are right.
Rob, I'm glad you also see this now as I know you have been concidering going this route yourself. I think its funny that people always think that though. In comparison a 400rwhp 347 would equate to a 348rwhp 302 based on rwhp/cube, and we all know that 348rwhp NA 302's are NOT all that common, so why do people think 400rwhp 347's are?
95Vert
New Member
Killercanary said:In comparison a 400rwhp 347 would equate to a 348rwhp 302 based on rwhp/cube, and we all know that 348rwhp NA 302's are NOT all that common, so why do people think 400rwhp 347's are?
I really think people think that way because they are spending a good amount of money and think that their new combo should give them at least that much gain. I know that's how I thought before I actually knew anything.
My 347 with all the parts I'm putting on it has a Flywheel HP rating of 410. It will be way short of 400 HP at the wheels. I'm guessing around 360HP or so. Now what Im hoping for is high TQ numbers.
VibrantRedGT said:
Joe, who is doing your cam? I take it you're done with the supercharger thing?
If you're starting out from scratch and have a 400+ goal in mind and you're working with someone good that knows there stuff, 400hp is cake walk. Now, I do not think i'll hit 400hp in mine as I feel i'm a bit head limited (which I knew going into this) but I also have a few bottle necks in my exhaust holding me back. The lips on the bbk longtube collector is tiny as hell and necks down to under 2.5". Thats one bottle neck. The other is i'm still using a 2.5" mid pipe where as a 3" would be ideal but it would be stupid to attach a 3" pipe on a bbk collector that necks down to under 2.5". I'm also being optimistic and not hoping for big results this way if I get big results I can be happy
I did tell Ed what I wanted so when/if I dyno, we'll see. I would consider my cam somewhat "healthy" at 236*/242*, though it doesn't drive or sound as 'big' as it is. One thing that has me wondering what i'll make is an example on FTI's site. There was a guy in the feedback section with a chp 347, TW heads, rpm intake, Ed's cam and 1 3/4" longtubes and he made 373rwhp. Now mine, i'm spinning a little higher with a cam that was designed for good mid-upper rpm power NOT low end and I have a lot more intake (TFS r over an rpm). Hmm, makes me wonder. I was gonna throw it on a mustang dyno, but maybe i'll use a dynojet to get the bigger dyno numbers for my sig 
302fordracer
New Member
dont rule out gt40s as a good power producing head...I've got over 300 at the wheels using gt40p's...with stock compression and stock displacment..
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