What does 'ported and flowed heads' mean?
Discussion
bor said:
Guys, I'm changing the bath example to a shower. Sorry, the bath thing was a bit misleading.
One of those nice power showers on full blast. All the water going down the plughole. Plughole gets quadruppled in size. Any difference ?
That's actually a better analogy.
Assuming the plughole as standard can cope with the shower on full flow, there's no point in increasing its diameter.
However, with a larger plughole, you then have the option of fitting a more powerful pump to your shower and forcing more water through the system!
Probably the drainpipe would then back up, so you'd need to increase its size (free-flow exhaust) or add a drain pump (extractor manifold).
Of course, if you can't make use of all this extra water whlist showering, its all totally pointless, so fit a bigger beer belly to wash (increase cylinder bore).
bor said:
Bor,
No, because if the water was there it would flow out faster...
Guys, I'm changing the bath example to a shower. Sorry, the bath thing was a bit misleading.
One of those nice power showers on full blast. All the water going down the plughole. Plughole gets quadruppled in size. Any difference ?
Just going to get a sandwich. Back in 5.
Bor,
I can see what you are trying to say, but its not quite right. The plug hole can only get rid of what the shower is producing. If the shower produces more water than the plug hole can remove the bath will fill up. In this scenario a larger plug hole would make a difference.
Its the same with the engine, the more air you can get in, ( and out ) the more power you can get. I agree that at some point there would be no more gain, but that is limited by the amount of metal that can be physically removed from the head in question.
If you can get more air in and out, at a reasonable temperature, you will get more power.
Rgds
Pete
i pressure tested my head last year and it was cracked, so i fitted one that had been both ported and gasflowed but the rest of the engine is still stock (except for a custom exhaust but standard manifold)
so, in my experience i have increased the power but the torque is not quite as noticable... i'm sure it has gone up but not in relation to the power... this is my opinion and i haven't had it on the rollers since i put the new head on so cannot confirm this...
but, also porting your head works best if you port-match it to your 2 manifolds (inlet/exhaust) which i haven't done so my car is definately not running to its optimum!
so, in my experience i have increased the power but the torque is not quite as noticable... i'm sure it has gone up but not in relation to the power... this is my opinion and i haven't had it on the rollers since i put the new head on so cannot confirm this...
but, also porting your head works best if you port-match it to your 2 manifolds (inlet/exhaust) which i haven't done so my car is definately not running to its optimum!
In my experience any single cylinder work done at pre-prototype stages has been done to optimise power and emissions. The shape is mastered and prototype heads are made with the porting and combustion chamber optimised to suit the requirements.
Where the bean counters come in is tooling maintenance budgets for both machining and sand cast die maintenance. If the sand is inaccurate, and the machining inaccurate then the result is a less than optimal head. In all honesty though, in the last 10 years manufacturers have really raised the game and I think it's less important than it used to be.
Additionally engines need to last a long time. Porting to remove bosses etc that restrict flow is great on an engine that does not have to live for a long time but it'll be at the risk of durability. So often the engine is 'compromised' to make it last.
If you take a modern 4v/cyl design then you're only going to see a gain where the weak link is in the engine. In some cases, there's insufficient valve lift or overlap, an overly restrictive throttle or manifold.
There are certain tuners who seem to have a reputation above their peers for work on certain engines. I'd look at what they are selling. If you've got a racer and you need every advantage, and blueprinting is allowed but with no other mods, then that'll make the engine develop the most power, but in many other cases a variety of mods will make the engine develop ultimate power.
Just remember though that in many cases a good road car has a broad spread of torque at the expense of higher rev power. Driving a racing engine is not much fun unless you're on the racetrack or in some form of competition. Also remember that the more power the engine develops the more stress it is under. That's why some engines need new pistons, cranks, rods in higher levels of tune - you have to ask yourself if it is worth it for a road car or to just fit a bigger engine.
Where the bean counters come in is tooling maintenance budgets for both machining and sand cast die maintenance. If the sand is inaccurate, and the machining inaccurate then the result is a less than optimal head. In all honesty though, in the last 10 years manufacturers have really raised the game and I think it's less important than it used to be.
Additionally engines need to last a long time. Porting to remove bosses etc that restrict flow is great on an engine that does not have to live for a long time but it'll be at the risk of durability. So often the engine is 'compromised' to make it last.
If you take a modern 4v/cyl design then you're only going to see a gain where the weak link is in the engine. In some cases, there's insufficient valve lift or overlap, an overly restrictive throttle or manifold.
There are certain tuners who seem to have a reputation above their peers for work on certain engines. I'd look at what they are selling. If you've got a racer and you need every advantage, and blueprinting is allowed but with no other mods, then that'll make the engine develop the most power, but in many other cases a variety of mods will make the engine develop ultimate power.
Just remember though that in many cases a good road car has a broad spread of torque at the expense of higher rev power. Driving a racing engine is not much fun unless you're on the racetrack or in some form of competition. Also remember that the more power the engine develops the more stress it is under. That's why some engines need new pistons, cranks, rods in higher levels of tune - you have to ask yourself if it is worth it for a road car or to just fit a bigger engine.
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