Cylinder Head; performance increase for FI too?

[Shaun]

Re: Cylinder Head; performance increase for FI too?

Shaun, did you read all this in books or you are stating actual facts from experience?

This is all from experience.

Or replacing pistons with hi dome heads, or reducing head gasket thickness

Yes those as well, but with reference to the term "surface grinding" I mentioned procedures carried out on block and heads. Terms used over here are surfacing, decking. Grinding usually implies a stone or abrasive of some sort, not carbides or cutters. Terms may differ between countries.

I have never heard of a head being rehetaed to compensate annealing before, if it is welded, it will get surface ground, if the ports are welded, it will get ground for gasket surface and any other anomaly.

With large amounts of welding like chamber fills, or deck buildup for aggressive angle mill, re-heat-treat is necessary. It is intensive as everything needs to come off the head for heat treat and then re-installed (guides, seats).

It is called surface grinding, not using a grinder, using a sufacing tool, most often a cutter.

As in earlier para with terms.

what a load if bullshit, hahahaha, a breaker, thats a good one. Who in their right mind would put or manufacture a part designed to break as an internal component?

No need for coarse talk. To answer, the same people who would prefer to replace valves, instead of say valves, pistons, rings, and everything it takes a long with it. Analogy is driveline. If you strengthen everything to take equal load before failure, and you have no weak link, and you go on to raise torque and grip, you will come to a point where you overcome the system all at once and break everything in the driveline. Fortunately this is hard to achieve and usually only one thing at a time breaks. If I had to pick a component that I wanted to let go instead of an expensive diff, I'd make sure it didn't exceed the capacity of the diff, so I would know the diff is protected.

 

[phil]

Re: Cylinder Head; performance increase for FI too?

Not coarse talk mate, sorry to offend you in anyway. For the diff scenario yes i understand a nd one would hope thst would be the uni joint.
Anyway, i think i better go back to uni, I have a headache now

cheers Shaun

 

[BlackStealth]

Re: Cylinder Head; performance increase for FI too?

Now i am having information overloaded. But, thats my objective....

Oh well, Jeremy, i think let's give this a skip. Can't do one without re-enforcing the others. Whole package plus labor just will kill us straight up. Even when the claimed "competition porting expertise" is imported from USA....the porter is Russian!

 

[vegz07]

Re: Cylinder Head; performance increase for FI too?

This is a good readup on this topic.. guys, Enjoy..

Puma Race Engines Tuning Guide - Tuning Turbo Engines

 

[Shaun]

Re: Cylinder Head; performance increase for FI too?

His site has been around for at least 5 or 6 years. Good articles. Can't specifically remember anything I disagree with, but my memory is fuzzy.

Bear in mind that this claimed importance of porting for both NA and FI engines - street or race, comes from a person who makes a living porting heads. Financial motivation...

Take two indentical stock or low tune state FI engines, pick a typical and reasonable street budget of anywhere from 10-15K SGD for each. With one, mandate porting as one of the changes. Leave the other one free to have heads unported. The latter will make more power, and almost certainly be more efficient. Beyond a certain budget, the rule no longer applies, but that line is very roughly around 50K SGD because there is so much else you can do for larger gains in power and efficiency, at lower cost.

 

[MazzyMan]

Re: Cylinder Head; performance increase for FI too?

Now i am having information overloaded. But, thats my objective....

Oh well, Jeremy, i think let's give this a skip. Can't do one without re-enforcing the others. Whole package plus labor just will kill us straight up. Even when the claimed "competition porting expertise" is imported from USA....the porter is Russian!

Bro...head job and porting may help you alittle but its an irreversable job hor. In good hands i am sure you will gain some hp and nm...in the wrong hands you will be worse off compared to stock.

I will give you an example from an NA engine of which a person you and i know who was responsible in the full head job plus major porting:

Lancer 1.5L 12valve engine after being magically touched...kicked the ass of a Mivec 1.6L twin cam from 1st to 4th gear. No ECU involved...just pure mechanical magic hor.

Anyway lower compression pistons in my opinion means you plan to go for even higher boost than what you already have. Thus, changing stronger bearings and even aftermarket conrods will make sense but depends again on how much more boost you intend to push out. Dun forget...aftermarket engine bolts while you are at it and a metal head gasket calculated to your set-up requirements too.

Bare in mind that more boost = much more heat. So you could even be looking at a larger intercooler and perhaps better and more efficient cooling for the really hot running engine.

Most importantly, which is something "plenty" of people dun care about is with more boost comes more fueling....larger injectors might just be required to hold that larger amount of boost for tune up this = bad bad fuel economy.

Head job and porting is getting a little stale and rare these days (apart from race engines) as its cheaper and simpler to plug and play forced induction kits. Like SOOOOO many car owners have done.

 

[yendor]

Re: Cylinder Head; performance increase for FI too?

I hope i do not ruffle any feathers here when i say that there are distinct differences between a NA and a FI car. You cannot compare them. Method of Power delivery is the biggest diff which may not flow with some people. Perhaps Desmond can say a few things about this issue having had a high rev high strung NA to a FI car to a hugh displacement NA engine.. Handling aside...

In FI cars, the flow of gases is the same as in NA cars cos physics do not change. Gas has weight and thus inertia... Porting if done correctly helps the engine breathe better but too many shops here (locally) have ruined the trade. There are botched jobs that actually flow worse than stock ports but look very very big, poor grinding or surfacing of the heads that leads to water/oil leaks.

Ask yourself what are your aims. Good street machine, economical runabout, 0-100 monster, track car or what...

All of these cars will have different requirements and equipment. Thus their developmental roadmap is different. The only thing that links them together is that the car is a system of systems working together.. If there is a weak link, the entire chain fails..

cheers

 

[vegz07]

Re: Cylinder Head; performance increase for FI too?

yup agreed on what u say.. seen alot local ported heads.. ermm, if you just want normal remove of the rough castings, very basic polishing, local still can.. but if go for the real Port & Polish, local forget it..better leave it to the professionals to do it with flow bench test reports before and after and P&P as their ricebowl. This is the real P&P. if you seen the difference you will understand.

 

[Shaun]

Re: Cylinder Head; performance increase for FI too?

In FI cars, the flow of gases is the same as in NA cars cos physics do not change.

In earlier post, it was described how FI flow is different from NA flow. The physics of sonic choke varying downstream and upstream pressures and the effect of each combination on both volume flow and mass flow are well documented in automotive and aerospace tests, and there is no disagreement.

If the points are false, please explain why.

Ignoring pulsed flow, any remotely proper test method for FI heads requires an entirely different test bench vs NA engines - one which consumes an enormous amount of power to create realistic differentials. I have not come across anyone or company that has built such a bench, or perhaps it has not been made public.

The fact that good NA heads make great FI heads, does not mean that flow is the same. As mentioned, they are different - just that in FI, outside of actual structural integrity under boost, the higher pressures and densities in the port generally move it in the direction of more stable.

Below high limits, dollar for dollar, you are better off making large gains in improving the system, rather than small gains through time consuming and risky (given the lack of proper equipment and experience in certain regions) processes.

 

[yendor]

Re: Cylinder Head; performance increase for FI too?

Well. I am refering to gas flow. On the intake side, you are moving higher pressure gas down through the throttle, plenum, intake tract, port and finally past valve seats. Thus when you increase the pressure (via SC or Turbo) the pressure differential increases dramatically and thus flow is increased. Of course since there is mass, there will come a time when flow cannot be increased a certain point cos the valve set area becomes an expansion valve (like in an air con system).

Exhaust really different cos the collectors are of different purposes..

Cheers

 

[Shaun]

Re: Cylinder Head; performance increase for FI too?

All earlier references of mine have been to gas flow.

In FI systems, and given typical port cross sections, the point where net power gain mass flow plateaus is far beyond other limits - mechanical and thermal. Mass flow choke is not a limit or concern.

In NA systems, both volume and mass flow choke are very real limits and of major concern.