G
Guest
·Hi all,
Some time ago I remember a few people asking and/or debating about the benefits (if any) of having an Evo cylinder head ported, polished, gas-flowed, etc... (here in the Philippines, and I believe maybe in America, also referred to as getting headworks ). I know for instance, that there's a pretty popular school of thought that says you don't really need headworks with a forced induction engine, and therefore getting an Evo head ported/polished with bigger valves, etc will yield marginal improvements in power.
Anyway, I'm glad to say that I've just enjoyed a very measurable and fairly significant improvement in power, from fitting a pretty heavily modified head onto my car (Evo 5). The head has been gas flowed, has bigger valves, titanium retainers... but am currently still running stock cams and valvesprings.
Here's a bit of my car's tuning history so far, which I THINK demonstrates the improvements that may be derived from a properly done head.
1) COMPLETELY STOCK
- car dyno'd at about 210-212HP @ the wheels
- this is to be expected and about right, as stock Evo's do just that on the Dynojet RR where I get my tuning done);
2) WITH INTAKE/EXHAUST AND APEX'I AVC-R / S-AFC
- car dyno'd at 232HP @ the wheels
- boost set to peak at 1.1 bar with the AVC-R
- S-AFC used to fine tune fuelling
3) WITH THE NEW HEAD
- car dyno'd at 253HP @ the wheels
- boosting between 1.1 to 1.2 bar (spike), holding at about 0.9 to 1.0 bar
- (as mentioned,) head has been gasflowed, with bigger valves, titanium retainers
- stock cams, but with HKS adjustable camgears
- stock valvesprings
note that with this set-up, I was unable to maximize the potential of the improved flow, because with the limited adjustments allowed by the S-AFC, I would experience intermittent fuel cuts. A programmable ECU was needed, and not having the resources to purchase a Motec, I went with the Apex'i Power FC.
and finally, just today:
4) WITH THE POWER FC
- car dyno'd at 273HP @ the wheels
- as above, still getting boost spikes to 1.2 bar, but settling down at between 0.9 bar to 1.0 bar
- Power FC used to eliminate fuel cuts by remapping ignition timing and fuelling
The upshot: of the sixty HP I've gained over stock from mods and tuning, IT SEEMS I'VE GAINED ABOUT FORTY (40) HP LARGELY FROM THE MODIFIED CYLINDER HEAD. Of course, I wouldn't have been able to maximize the head without the new ECU, but it seems a fair bet to say that just fitting a new ECU w/o changing anything else on the car, would NOT yield any significant benefits.
By this time, some of you are probably thinking: big deal, you could have saved yourself the time and effort to get that additional power, by simply turning up the wick on the boost! . I suppose I could just up my boost to say, 1.3 bar or more, but I'm afraid of my engine going bang (I still run the stock turbine and internals,) and wanted to see how else I could make power WITHOUT resorting to silly boost.
I have yet one more incremental mod to try, and that's fitting 272/272 cams. My tuner feels that doing this would squeeze out even more power from the head, as he says that the high flow characteristics of the head are wasted with the very conservative profile of the stock cams. Anyone have any ideas how much I'll gain? I suppose if I can get to 290HP @ the wheels with the addition of the cams, I'll be chuffed!
Anyway, I just thought I'd share this information here, for anyone who's interested. Am curious to hear what people think!
Cheers!
Some time ago I remember a few people asking and/or debating about the benefits (if any) of having an Evo cylinder head ported, polished, gas-flowed, etc... (here in the Philippines, and I believe maybe in America, also referred to as getting headworks ). I know for instance, that there's a pretty popular school of thought that says you don't really need headworks with a forced induction engine, and therefore getting an Evo head ported/polished with bigger valves, etc will yield marginal improvements in power.
Anyway, I'm glad to say that I've just enjoyed a very measurable and fairly significant improvement in power, from fitting a pretty heavily modified head onto my car (Evo 5). The head has been gas flowed, has bigger valves, titanium retainers... but am currently still running stock cams and valvesprings.
Here's a bit of my car's tuning history so far, which I THINK demonstrates the improvements that may be derived from a properly done head.
1) COMPLETELY STOCK
- car dyno'd at about 210-212HP @ the wheels
- this is to be expected and about right, as stock Evo's do just that on the Dynojet RR where I get my tuning done);
2) WITH INTAKE/EXHAUST AND APEX'I AVC-R / S-AFC
- car dyno'd at 232HP @ the wheels
- boost set to peak at 1.1 bar with the AVC-R
- S-AFC used to fine tune fuelling
3) WITH THE NEW HEAD
- car dyno'd at 253HP @ the wheels
- boosting between 1.1 to 1.2 bar (spike), holding at about 0.9 to 1.0 bar
- (as mentioned,) head has been gasflowed, with bigger valves, titanium retainers
- stock cams, but with HKS adjustable camgears
- stock valvesprings
note that with this set-up, I was unable to maximize the potential of the improved flow, because with the limited adjustments allowed by the S-AFC, I would experience intermittent fuel cuts. A programmable ECU was needed, and not having the resources to purchase a Motec, I went with the Apex'i Power FC.
and finally, just today:
4) WITH THE POWER FC
- car dyno'd at 273HP @ the wheels
- as above, still getting boost spikes to 1.2 bar, but settling down at between 0.9 bar to 1.0 bar
- Power FC used to eliminate fuel cuts by remapping ignition timing and fuelling
The upshot: of the sixty HP I've gained over stock from mods and tuning, IT SEEMS I'VE GAINED ABOUT FORTY (40) HP LARGELY FROM THE MODIFIED CYLINDER HEAD. Of course, I wouldn't have been able to maximize the head without the new ECU, but it seems a fair bet to say that just fitting a new ECU w/o changing anything else on the car, would NOT yield any significant benefits.
By this time, some of you are probably thinking: big deal, you could have saved yourself the time and effort to get that additional power, by simply turning up the wick on the boost! . I suppose I could just up my boost to say, 1.3 bar or more, but I'm afraid of my engine going bang (I still run the stock turbine and internals,) and wanted to see how else I could make power WITHOUT resorting to silly boost.
I have yet one more incremental mod to try, and that's fitting 272/272 cams. My tuner feels that doing this would squeeze out even more power from the head, as he says that the high flow characteristics of the head are wasted with the very conservative profile of the stock cams. Anyone have any ideas how much I'll gain? I suppose if I can get to 290HP @ the wheels with the addition of the cams, I'll be chuffed!
Anyway, I just thought I'd share this information here, for anyone who's interested. Am curious to hear what people think!
Cheers!