Curious... How is it that 347's are getting in the same rwhp as 408's?

As stated earlier, the smaller cubic inch engine is going to need to be driven at a higher rpm to acheive the same power potential. There are some very simple formulas to determine the amount of revolutions needed to acheive the same average piston speed.

The basic formula that everyone knows is as follows:

Determining piston speed...

Formula: Stroke x RPM / 6

So let us take a 6,000 RPM 347 CI engine.

347 CI example: 3.4 x 6000 / 6 = 3,400 average piston speed in feet per second.

400 CI example: 4.0 x 6000 / 6 = 4,000 average piston speed in feet per second.

But what if you want to figure out how much one needs to shift the smaller cube engine compared to the larger cubed engine to get the same piston speed?

All you have to do is change up the formula a little bit...

Formula: Wanted piston speed (larger stroke) x 6 / Stroke used (smaller stroke)

So let us take a 4" stroke engine (408) shifted at 6,000 and see how high we need to revolve the 3.4" (347).

4000 fps x 6 / 3.4" = 7,058.82 RPM is needed for the 347, compared to a 6,000 RPM 408.

So you can see that you can simulate more cubic inches with higher RPM.

A 6,000 RPM 408 is roughly the same as a 8,000 RPM 302...

So you can see why some of the high revving 302/306's are making some big numbers with the right parts to support the extra air needed.

What ever happened to the street car I can remember when a 400 horse street car was insane back in the day. But the bar always get raised and things start to get ridiculous. After years of replacing broken parts and spending stupid money to keep stuff together and running top notch I am getting tired. I can honestly say I think my favorite car now is my new 07 GT. Its fun as all get out and all it takes is gas whenever the tank is empty!(oh no I'm getting old)

final5-0 said:

It seems to be all the same to me ... over and over and over

Everybody (yes...me too) loves to TALK about ... big power

and then

There is the REALITY of ... big power

Reality will tell you that 400rwhp or more is gonna cause you to deal with

Transmission Weakness
Suspension Weakness
Rear End Weakness
Unibody Weakness
Cost to operate it
and
More

after you get that high horse power motor built

You can really put a BIG strain on your little 94-95 Stang with a simple
NA h/c/i combo :Word:

I'm not trying to be critical and bring everybody down

It just seems like more and more peeps are running around with their
heads in the clouds and thinking big power is so easy to come by

It almost seems like the attitude is

"Lets build a nice little ... Street Car"

"400rwhp or more is just a bit more effort than a typical bolt on combo"

and

"You'll suffer no compromises at all if you go for that level of performance"

Grady

Click to expand...

Supporting Mods is a major concern.

I just destroyed my Tremec TKO

I have spent more money building the rest of my car to support the 400+ rwhp than I did making the HP from my 347 to break them.

I'm going to start a trophy case to keep all my broken parts in.

What would a 408+ ci engine built the same way as my 347 do to my drivetrain.

I know it all comes down to the parts you put on it. I have a friend that runs a 427ci stroker that made 850hp on an engine dyno.

The HP is there you just have to toss the right cash at it

kck6894 said:

Supporting Mods is a major concern.

I just destroyed my Tremec TKO

I have spent more money building the rest of my car to support the 400+ rwhp than I did making the HP from my 347 to break them.

I'm going to start a trophy case to keep all my broken parts in.

What would a 408+ ci engine built the same way as my 347 do to my drivetrain.

I know it all comes down to the parts you put on it. I have a friend that runs a 427ci stroker that made 850hp on an engine dyno.

The HP is there you just have to toss the right cash at it

Click to expand...

Exactly the thought process I was trying to get across

A high hp motor is great
but
The rest of the car should be able to support it

Kinda like ... Sex is great
but
Things can happen after the good feeling is gone :Word:

Go into a high horse power combo with your eyes ... WIDE OPEN

Thats all I'm trying to say here

Grady

PUNISHER RACING said:

What ever happened to the street car I can remember when a 400 horse street car was insane back in the day. But the bar always get raised and things start to get ridiculous. After years of replacing broken parts and spending stupid money to keep stuff together and running top notch I am getting tired. I can honestly say I think my favorite car now is my new 07 GT. Its fun as all get out and all it takes is gas whenever the tank is empty!(oh no I'm getting old)

Click to expand...

i hear ya on this ... i am at the point where i don't want to have to worry about it or mess with it, i just want to be able to get in it and go

Pokageek said:

Yep me too lol!

Click to expand...

Me three