** Rebuilding a Stroked/Turbo VT Ecotec **

[Pub247]

Comparison..
isnt that what dyno and flow benches are for?

I havent really followed the whole ecotec craze but i Have to agree with delcowizard. How hard is it to compare these heads to stock its not like stock heads are unicorns.

Everyone i know PERSONALLY who has heads ported gets a sheet thats show before and after figures.

In the end that the whole point to the process

 

[delcowizzid]

DW,


From feedback we've received from customers, with actual product experience and in the hands of professional head porters, these alloy heads flow about as well as a set of good factory ported heads out of the box. Where they really shine though is when they're ported, reaching flow far greater then the "best" factory ported head, with the simple fact that they have much more meat to play with, coupled with revised chamber and runner geometry off the bat

so for twice the price of porting a stock set of heads you get the same gain ,then another $1400 on top for porting to get more .man $4500 for a set of heads that outflow ported stockers definately not bang for buck LOL

 

[MACE]

Comparison..
isnt that what dyno and flow benches are for?

I havent really followed the whole ecotec craze but i Have to agree with delcowizard. How hard is it to compare these heads to stock its not like stock heads are unicorns.

Everyone i know PERSONALLY who has heads ported gets a sheet thats show before and after figures.

In the end that the whole point to the process

To compare before and after results on the same car or same set of heads on the same dyno or flow bench yes, I 100% agree. To test two different cars/or heads on the same machine ideally, over a short period of time, would give an accurate result if product A is better then product B or visa versa.

To compare between different dyno/flow benches to two different cars/heads and treating them as accurate results then that's asking for trouble. Excellent example of this would be the power figures a car on a dyno dynamics dyno would make compared to a mainline, noticeable difference there even when the same car is tested! As useless as these results are, things get worse when your trying to compare the same component type, modded differently, on two different machines.

As for comparative testing of these heads compared to stock that's not a problem, in fact would be the best way for people to control or calibrate a test if they wanted compare tests done on different machines etc. The results then could be scaled on excel for a fairly accurate visual comparison. How many people do you think would have done this though?

 

[MACE]

so for twice the price of porting a stock set of heads you get the same gain ,then another $1400 on top for porting to get more .man $4500 for a set of heads that outflow ported stockers definately not bang for buck LOL

How much do you think a set of quality race ported factory heads, new valves, springs, retainers, collets, new guides etc. costs in Australia? Not "mates rates" prices?

You've never seen these alloy heads up close yet you're quoting on how much they'd cost to port? Even at $100 an hour they definitely don't need 14 hours of work to blow a set of factory heads out of the water, hence the premium. At this level of build "bang for buck" start wearing thin there is no way around it.

 

[delcowizzid]

seems maybe they are not worth porting ZZP inform me theres only about 2-5% extra flow from porting as they allready have the short turn radius maximized out the box and the seats are allready blended into the bowls etc

 

[MACE]

seems maybe they are not worth porting ZZP inform me theres only about 2-5% extra flow from porting as they allready have the short turn radius maximized out the box and the seats are allready blended into the bowls etc

I don't agree with that statement complete. Yes they are an excellent head out of the box, however if you're game to port manifolds along with the head that quoted figure will easily be surpassed, honestly this is me speculating based on having seen the heads in person and experience with other tests in the past. Having taken to them with a set of calipers you can, proportionally, increase the overall geometry of the ports however this would require larger intake and exhaust runners

 

[MACE]

no i have not seen these in person but i have a network of tuners and engine builders around the world who have been involved in trailing these and have reverted back to ported cast iron heads i have also seen how easily damaged they are in boosted situations with not enough headstuds to hold them down as well as the ones with extra holes for more studs.there was a time i was searching high and low for alloy heads now i wouldnt even dream of running a set unless i got them for free to try you blow a head gasket they need welding and surfacing do that a few times they are only good for scrap.surely you must have some flow figures for a ballpark flow value i have flow figures for all stock holden buick and ecotec heads and ported flow figures from a reputable flow bench to compare them too

Despite aluminium having a lower modulus of elasticity compared to cast iron, the alloy heads have more meat resulting in a positive impact on moment of area in both planes. If I was a betting man, subject to the same load the alloy heads would probably be stiffer! As for repairing alloy heads, given the quality of the casting and someone who knows how to weld cast alloy properly, I can't see it being a problem with these heads with the appropriate filler wire and treatment etc. As for welding up factory cast iron heads, which often crack between valves, I'd give it a miss even with a welder who knows what they're doing, unless it was a Model T Ford cylinder head which are about as common as unicorns

 

[delcowizzid]

14 bolt turbo alloy head, arp studded with cometec gasket after lifting at 22psi messy stuff

 

[holden_4aw_lyfe]

Adam_88,

id be VERY impressed if i got around 550hp. I don't know what im expecting yet, im just doing things right, taking my time with the build, and getting the max potential out of the engine as much as i can. Remembering there's still 2 turbos to whack on after it's done

 

[holden_4aw_lyfe]

Adam_88,

Keep me posted with any problems you have, and what youve done to make your build better Let me know how power figures go