Marcello7x

iTrader: (10)

So as the title states im trying to figure out what rpm a 5.3/5.7 w/ cam along the lines of 230/230 .600/.600 likes to cruise at. I have a 60 mile daily commute and want to pick my rear so the sweet spot in 6th is at 80ish. My choices w/o this info would be 4.27 or 4.56.

BennyB

iTrader: (12)

auto or 6 speed car?

technicalninja

iTrader: (1)

I'd need to know what your 6th gear is (there are different ones) and how tall your tires are before coming up with a semi-accurate suggestion.
However, if your really trying to be in the middle of that cams operating range (most economical conversion of fuel to power / lowest BSFC brake specific fuel consumption) then you may not have a chance with those rear ends.
I would guess that cam (with a properly speced engine) would hit its lowest BSFC numbers in the 3500-4500 range.
To hit 80 mph in 6th at 4K I believe it will need much numerically larger gear. (IE 5.50 or larger). This would make 1st and 2nd gear pretty much useless.
I might suggest gearing your car for your target top speed in 4th at your intended redline and let the overdrives be overdrives.

Quick google turned up this site.
http://www.catherineandken.co.uk/sti/tyres.html
Pretty useful IMO

Your build looks light, how are you planning to install this power into the road surface?
Even with tall gears I think you'll be able to pulverize any street tire you can find.
Hope that site helps. It will let you play with any of the numbers.

I would think that cam would be into the beginning its "usable" range at 2200-2500 rpm depending on where you degreed the cam too (advance/retard).

Steve Gunn

I suggest 410/411's to get you into the 2000ish/80ish mark and still be fairly quick provided you're using an fbod trans and a 26in tire. If you have a great tune, you can cruise under 2000rpms with no trouble, but 230ish cams tend to buck a little at low rpms. 2000rpms will be nice and smooth. I've had 342's, 373's and finally 411's. Any shorter of a gear would make highway driving unpleasant, IMHO.

http://www.f-body.org/gears/

midevil1

iTrader: (17)

X2. 4.10's put you at 1900rpm at 70mph with 26".

Marcello7x

iTrader: (10)

Ok sorry for the missing info. The T56 is from an 02 camaro, so 6th is a .50.

Rear tires are most likely going to be 295/45/18, so more or less 25.66. With an online calculator it puts me at 83mph at 2100rpm with 4.26's, and 82 at 2200 with 4.56.

I wasn't trying to put it in its perfect operating range, just a nice smooth rpm. It might have been easier to ask when does the choppy idle of a cam start to smooth out.

Technicalninja my only plans for getting the power to the ground right now is to keep my 16gallon fuel cell full since it sits right over my rear! That and some nitto dr.

Arctic2002ss

I know that my cars runs good at around 85mph in 6th. That is about 1800rpms with 3.73s. It does not like anything under 1700 at cruise.

Marcello7x

iTrader: (10)

Thanks exactly the kind of info i was looking for.



Side note, i found a midpoint more or less a 4.33 for my rear. I actually did see any 4.26-4.27's that i thought i had seen earlier.