limited budget ,HEADS or DISPLACEMENT??

[grumpyvette]

I get asked this frequently.

the question usually goes something like

 

" look Ive got a VERY LIMITED budget, which should I go for,

great heads or a good large displacement short block,

IVE only got $1500, or $2000, or $4000 to work with??"

 

first ID point out its foolish to buy parts you won,t want in the finnished engine, and thinking thru the progression and steps will help make sure your not stuck with a non-running car for weeks or months at a time!

 

well having been this route a few dozen times (personally) and many more on other guys engine combos... Id put my two cents worth in,

OBVIOUSLY youll need BOTH to maximize any combos potential, and it depends a great deal on how large a displacement increase over stock your thinking about,

now if your only going from a 350 to a 383, the heads will obviously be a good value,as better heads and a matched cam can boost the hp noticably,but if your seriously building to maximize the torque and hp in the complete project and your eventually going to build the engine to maximize the power..

and if your thinking about a serious upgrade in displacement , say from a 327, to a 427 in a sbc or a 396 to a 496-632 in a bbc,...

I ALWAYS suggest going for the large displacement short block thats well put together FIRST.

youll never make killer hp without the good heads but you can use stock heads on a well built short block to make killer low rpm tq UNTILL you can budget and save for the heads you want, ESPECIALLY on a BBC combo as the heads, even the peanut port door stop design heads, flow more than the VORTEC sbc heads ,now of course theres the potential problem of differant clearances, and compression ratios with differant pistons and combustion chambers, but if it will fit and fuction ID go FIRST for the displacement an have a driveable car with the old heads while saving for the better ones. YOULL NEED TO THINK EACH STEP THRU CAREFULLY.

 

example

lets assume youve got a 350 hp 396 in your 66 chevelle, nova or camaro, and want a killer combo.

youve saved up $3000-$4000 and its burning a hole in your pocket, now you can buy a 496 short block or killer heads and a cam, and theres little doubt that the killer heads and cam sellected correctly will make more power than your old heads and cam on the new 496 short block...but think it thru THEN WHAT?

in a few months or years as your budget allows, youll want to upgrade, if the heads and cam were sellected for the 396 its not likely that they are near ideal on a 496 with its greater displacement and lower average rpm range..

if you sellected the short block first, the heads and cam can now be sellected to match.

NEXT

its simply faster and easier too swap heads on a good short block than it is to swap short blocks out at a latter date when the funds and parts become available

 

keep in mind the displacement and compression dictate to a large degree the torque, while the cam timing and heads flow rates effect the rpm range and peak power potential that displacement can reasonably achieve on a limited budget.

 

http://maliburacing.com/patrick_budd_article.htm

[John Scott]

As usual, the words of wisdom and experience. Thanks grumpy!

The only thing I'd add is then do your research on the builder. As a kid I spent 5 years collecting the right parts only to have them ruined by a flashy machinist, builder that dissappeared in under a year. Look for an estabilished builder, repeat customers, talk to the local drag or track guys and see who is doing great work and standing behind it. It can save a boatload of hard earned cash.

[Pete84]

. . .

 

youll never make killer hp without the good heads but you can use stock heads on a well built short block to make killer low rpm tq UNTILL you can budget and save for the heads you want, ESPECIALLY on a BBC combo as the heads, even the peanut port door stop design heads, flow more than the VORTEC sbc heads ,now of course theres the potential problem of differant clearances, and compression ratios with differant pistons and combustion chambers, but if it will fit and fuction ID go FIRST for the displacement an have a driveable car with the old heads while saving for the better ones. YOULL NEED TO THINK EACH STEP THRU CAREFULLY.

 

. . .

 

http://maliburacing.com/patrick_budd_article.htm

 

How much performance would you have to give up when building with old heads on the new block in order for the replacement heads to fit properly? Maybe a real simple example?

 

Great read!

[grumpyvette]

"How much performance would you have to give up when building with old heads on the new block in order for the replacement heads to fit properly? Maybe a real simple example?"

 

 

Ok thats easy

 

STEP ONE

 

the first 383 I built for my current 1985 corvette went from the stock 350s 240 rear wheel hp is based on a flat top piston and these heads

 

with this cam, (below)

 

and a very extensively ported stock TPI intake and plenum plus headers

 

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=114132&lvl=2&prt=5

 

 

 

to 317 rear wheel hp with the mildly ported stock heads and flat top pistons

 

THATS 77 hp for cam , mild port work increased displacement, headers and a mild cam.

 

STEP TWO

 

as soon as the budget allowed I installed heads similar too these heads

 

 

http://cgi.ebay.com/ebaymotors/Trick-Flow-twisted-wedge-G2-heads-Intake-and-hardware_W0QQcmdZViewItemQQcategoryZ33617QQihZ017QQitemZ270117925320QQrdZ1QQsspagenameZWDVW

 

http://www.hotrod.com/techarticles/trick_flow_twisted_wedge_head_dyno_test/

 

but extensively ported that flowed 248cfm at .400 lift and 262cfm at .500 lift and extensively ported the stock plenum, then added larger aftermarket runners

 

on that same 383 short block, hp jumped to 380rwh

 

THATS 63 MORE HP FOR MUCH IMPROVED HEADS, and a better intake

 

so the increased displacement and heads worked well together

 

STEP THREE

 

I then swapped to 11:1 pistons and this cam

 

http://www.cranecams.com/?show=browseParts&action=partSpec&partNumber=119661&lvl=2&prt=5

 

and an extensively ported stealth ram intake

 

results were 440 rear wheel hp

(yes I was forced to install a 3000rpm stall converter and 3.73:1 rear gear and trans cooler to run the new parts at this point)

 

THATS 60 HP MORE fore a MUCH BETTER INTAKE, CAM and HIGHER CPR

 

I then added a 250hp nitrous system jetted for 200 hp and started twisting off drive train and transmission parts so fast I have not got it re-dynoed yet

 

more interesting stuff to read thru a differant guy posted info source

 

http://www.ws6.com/mycar.htm

 

http://www.gmhightechperformance.com/tech/0307htp_hollley_stealthram_intake_third_gen_iroc/

 

http://www.eecis.udel.edu/~davis/z28/winter01/dyno/dyno021105/webpage021105.html'>http://www.eecis.udel.edu/~davis/z28/winter01/dyno/dyno021105/webpage021105.html

 

http://www.eecis.udel.edu/~davis/z28/winter01/dyno/

[280zwitha383]

This is good advice for people who are diligent at FINISHING projects and for high $$$ projects. For someone who rarely has any money to spend or changes their mind a lot I would say go heads and cam first. This is of course if you have a bottom end that will handle the power you want or close to it. You would hate to be stuck with a stroker bottom end and stock poor flowing heads with a stock cam. IF you do decide to do the bottom end, I would try to put the cam in that you want at the same time so you don't have to pull the timing cover/oil pan off again when you install the heads (of course you might have to buy different springs for your stock heads if they'll even handle that much lift). Better yet save up the money and just do it all at once if possible. Redoing stuff and having to buy new gaskets is just going to cost more money you don't have. Buying a core and building it up as you go while running your current setup is another good idea.