can someone tell me if there's an equation to use to figure out what size heads to get given a certain engine size and the desired optimal RPM range?

I want a TPI engine that will perform well between 2 and 5 thousand RPMs and I dont really know what kind of components to choose from. I've designed an engine so far that gets 482 ft lbs of torque but it's at 2500 rpms, which isnt good for a street car so im trying to move that power up the RPM range a bit. can anyone tell me the cfm rating for the stock TPI system, or at least tell me at which engine speed it works best with a 350? how about the stealthram intake? once i figure out the flow potential of these two intakes then i can get a starting point for the enigne designe.

I was thinking of a 350 (a modified L98) with some AFR 185 heads, a cam that was designed off the LT4 hotcam which includes 225 duration, .450 lfit and 112 lobe seperation and 1 5/8" headers. does this all seem in line? given a 350ci displacement do any of these numbers seem out of line for a 2-5k rpm engine? maybe some 190 heads instead or possibly a slightly shorter or longer duration.

i basically just wanna know what range i should be lookin in for each of these components given the desired RPMS range and engine size

 

If you want to move the power range higher, the best thing to do is to buy a new intake. BTW, how did you come up with the idea that a boat load of torque at low rpm is bad for a street car?

 

not BAD for a street car really, but to have an effective engine for a car the power band needs to be as wide as possible. sure it's fine that there was 482 ft lbs of torque, but it dropped off DRASTICALLY after 3000 rpms and at 5000 rpms it only had like 132 ft lbs of torque left in it. doesnt seem like the kinda thing you wanna use for a highway cruiser.
trust me, if i could make 482 ft lbs throughout the whole power band i'd be selling the shoes off my feet to build that motor!

what about the cam and heads though? shouldnt i be looking for larger flow heads and a longer duration cam if i want to move the power band up?

 

What's killing your desktop dyno is the fact that the TPI runs out of steam at 5k rpm. Try changing the manifold type to a tunnel ram or a single plane manifold and see what you get. Also, how did you come up with the "modified" hot cam? The hot cam specs out to 218/228 duration at 50 and either .492/.492 (1.5 rockers) or .525/.525 lift (1.6 rockers) on a 112 LSA. You might also try entering the hot cam specs with a world product head and a TPI setup.

 

I'd really love to know who told you this lie! My 388 made 486 Ft. Lbs TQ at 3000 RPM's and only 319 RWHP,

You may think only 319 HP?? But guess what that TQ makes this car get-up and go, quick enough to run 11's. So it doesn't necessarily need gobs of HP to whoop some LT1/LS1 butt!!

Torque is my friend, and yes mine is driven daily (that is once i get it put back together), until then i drive my SS (slow car)

 

how would the stealthram intake work with the stock computer? i know i can get the stealthram system for 700 but tha tdoesnt include the computer. that's just the intake and fuel rail.
what do you guys think?

 

Modified for extra lift Vortec heads, TPI Vortec SDPC intake and a properly matched cam of short duration would make a serious street beast. It's not rare to see 500+lb-ft out of a TPI style intake motor big cube SBC even at 3000rpm.

Slush92RS has a properly matched long tube runner combo.

 

but what do you guys think about the stock computer though? does that need to be replaced to go with a larger intake system or high performance application?
what rpm range do you think the stealthram would have optimal flow at? and what size heads would you suggest go to with that rpm range?