347 + power adders

[dadslx]

hey just wondering if its safe to run a power adder on a 347. i purchased my 347 and had it installed and the guy built it for a supercharged application that fell threw. basically my setup is this
fully forged bottom end
custom cam i think its .514/.533 ( ground for supercharger in mind )
tfs tw heads fully ported
holly smax 2 intake w/ 70mm tb and spacer
73 mass w/ 24 lbs injectors ( i know too small )
short belt setup alt, water and crank only.

im wanting 11's in the quarter how much n2o would it take verses say a novi 1000 supercharger. would either be safe to run on the motor???. and out of curiosity what do you think my hp/tq numbers are with just motor?..thanks folks

 

[5spd GT]

What kind of boost numbers are you looking at acheiving on top of the 347 cube displacement?

I hope you have an aftermarket block, because the stock one is just not going to maintain strength, and will give way.

With lots of boost, I would go with a 331. More piston crown thickness.

With some mild boost, a 347 with some good pistons will be just fine.

The 5.315" rod combo is a better choice over the 5.400" rod combo, if you want to get technical.

 

[dadslx]

well i do have the 5.4 rod. the pistons are forged for the tfs tw heads. i only want to run 6-7 psi. the block is stock but does have a girdle. to compensate for the longer rod im running a 7 qt pan w/ hi flow oil pump. but either way i plan on rebuilding at 40k miles anyways. would n2o be a safer bet?..i'm also running 9:1 c/r if that makes a diffrence?

 

[5spd GT]

The boost level is fine, but the block could be a problem...

 

[1991vert]

i never understood this. people throw all types of money into stock blocks...and for what? they know it's gonna break! save up for a better block first. do things right the first time!

 

[ninety15.0]

a mild 347 (depending on the rest of the combo) with 6-7 psi will be fine. You are probably looking at 450-475rwhp with a setup like that. If you have a conservative tune, head STUDS (not bolts) and good head gaskets you'll be alright.

 

[2000xp8]

a mild 347 (depending on the rest of the combo) with 6-7 psi will be fine. You are probably looking at 450-475rwhp with a setup like that. If you have a conservative tune, head STUDS (not bolts) and good head gaskets you'll be alright.

The problem with this theory, is that 425rwhp is very obtainable with no boost at all, so why bother dropping money on a power adder.

Seriously worked TW's, custom cam, a good intake, and an 80mm maf with 30's, will do it.
I've seen 347 combos make as much 477rwhp in street form, not your typical numbers, but it can happen, i'd still try and set the car up NA to get 425rwhp, which has a very good possibility of outrunning a boosted 475rwhp car.

 

[5spd GT]

When trying to run that type of power, you need to keep in mind, how streetable is streetable?

A 477 rwhp 347 is the equivalent of a 415rwhp 302.

So take that for what you will.

How much manifold vacuum do you need? How many rpm do you want to run? Valve spring life?

 

[blackened88lx]

im wanting 11's in the quarter

You're all missing the point. He wants to run 11s. Your current setup will easily run 11s with good 60s. You might be ok if you run a 100 shot or less once in a while, but it's probably not worth the risk. I wouldn't even consider adding boost to that combo with a stock block. If your block splits, it's very possible that it will take out your expensive stroker rotating assembly, your heads, and even your intake.

i never understood this. people throw all types of money into stock blocks...and for what? they know it's gonna break! save up for a better block first. do things right the first time!

Agreed

 

[2000xp8]

When trying to run that type of power, you need to keep in mind, how streetable is streetable?

A 477 rwhp 347 is the equivalent of a 415rwhp 302.

So take that for what you will.

That's why i was saying to shoot for 425rwhp, which IMO is a modest obtainable goal, and will run easy low 11's with traction.

 

[5spd GT]

That's why i was saying to shoot for 425rwhp, which IMO is a modest obtainable goal, and will run easy low 11's with traction.

I still believe shooting for a 370 rwhp 302 is going to be a bit unstreetable to most. But for the track, lots of fun

I have seen a 306 pushing 400 rwhp, but he revved it a few hundred rpm shy of 8,000 RPM, ran 12.25 compression, race gas, vacuum pump, etc.

 

[dadslx]

well i got the pony back today and i'll be honest i wouldnt run any power adders. its scarey fast as it is. the tires wont grip and my aod cant handle what i have now. what will a stock aod handle?..im going to buy a well built trans instead of the supercharger and get some nice sticky tires. anybody have any ideas on how to get the power to the ground, what i have in mind is
275/50/15 mt et streets
traction bars
drag launch suspension from eibach
aod street dominator by lentech w/ 3500 stall

ps the came i installed is just nasty..lol..i have to jam the brakes on at redlights or it just pushes forward. i need to take some film clips and post them.

 

[2000xp8]

well i got the pony back today and i'll be honest i wouldnt run any power adders. its scarey fast as it is. the tires wont grip and my aod cant handle what i have now. what will a stock aod handle?..im going to buy a well built trans instead of the supercharger and get some nice sticky tires. anybody have any ideas on how to get the power to the ground, what i have in mind is
275/50/15 mt et streets
traction bars
drag launch suspension from eibach
aod street dominator by lentech w/ 3500 stall

ps the came i installed is just nasty..lol..i have to jam the brakes on at redlights or it just pushes forward. i need to take some film clips and post them.

I kinda figured it would be enough power, you have the right idea about worrying about the trans next, because the aod probably won't last long.
The rest of your plan sounds good.