Engine experts: Gami Injectors, porting, polising, balancing, blueprinting

[Tony_Scarpelli]

I know very little about these topics and I thought it helpful to anyone wondering about engine performance to understand these terms and what they mean.

Gami Injectors are supposed to narrow the difference between your hottest and coldest CHT/EGT's so you can run the engine a bit closer to the edge for better performance....I do not really know much about this but what are the issues?

What is porting and polishing and why would you want it done to an engine?

What is balancing the engine or Blue printing and why would you do it?

 

[Tom-D]

I know very little about these topics and I thought it helpful to anyone wondering about engine performance to understand these terms and what they mean.

Gami Injectors are supposed to narrow the difference between your hottest and coldest CHT/EGT's so you can run the engine a bit closer to the edge for better performance....I do not really know much about this but what are the issues?

Price? they work and pay you back eventually.

What is porting and polishing and why would you want it done to an engine?

Back in the day of sand casting the casting came out pretty rough, and the hot rodders knew they could get better flow in and out by porting and polishing the intake and exhaust, better flow more power.
Now with much better investment casting they come out of the mold pretty much as good as they can be.

What is balancing the engine or Blue printing and why would you do it?

that is an attempt at getting the engine to run smoother by making all the like parts weigh the same. how much it works is a matter of how bad it was to start with.

 

[Henning]

Porting and polishing is about increasing your airflow into the cylinder and out of the cylinder. We often change the shape of the intake pockets to clean up the swirl to give a more even distribution of the fuel air mix in the cylinder, reduce turbulence (to a degree, you need to keep some) and help keep the fuel atomized. Thing is, if you don't really know what you're doing, you can screw things up. Until the Vortec head for the small block Chevy, they all needed some porting work. When my buddy brought me a new set of Vortecs and asked me to do my stuff to them, I looked them over and told him there was nothing to do, Chevy finally got it right. A couple years later they scrapped the whole small block lol. True polishing one only does in the exhaust port, intakes I make no finer than 80 grit, and the sanding pattern matters (to a degree, only critical in full on racing applications where every .001 second counts). On an airplane engine that's only turning 2500rpm though, the only thing I would bother with is match porting the induction runner to the head runner including the gasket (it provides the template to match the two) to assure a clean transition. With a turbocharged engine, this all becomes extremely LESS critical as you have pressure on both sides of the system, and most all of this is about free flow and scavenging under vacuum. A clean match port is about all I would bother with and I would spend my money on a cam with a reduced split overlap to increase the turbo efficiency.

Balancing is all about reducing damaging vibration which besides tearing things up will hinder the ability of the engine to turn high RPM due to increased friction. Again, on 2500rpm engines, this isn't super critical within the engine, although I would weight balance the prison/rod assemblies to each other. More critical on aircraft engines is dynamically balancing the prop, this is low cost and high value.

GAMI injectors are about matching the fuel flows between the cylinders to match EGTs allowing you to run smoother and safer in the LOP ranges. You only need them if your stock injectors leave you with a pretty good temp spread between them. If you lean your first cyl 20 LOP and your last cylinder is at 50-75 ROP, you'll likely want a set if you want to run LOP otherwise you'll either be rough or put a cylinder into a risk of detonation.

 

[mtuomi]

With a turbocharged engine, this all becomes extremely LESS critical as you have pressure on both sides of the system, and most all of this is about free flow and scavenging under vacuum. A clean match port is about all I would bother with and I would spend my money on a cam with a reduced split overlap to increase the turbo efficiency.

Do the turbocharged airplane engines have higher or lower exhaust manifold pressure than boost pressure under high power operation?

 

[Henning]

Do the turbocharged airplane engines have higher or lower exhaust manifold pressure than boost pressure under high power operation?

I've never measured it, but I would think it to be lower once the pressure is stable since the turbo itself will provide some scavenging effect once spun up.

 

[mtuomi]

I've never measured it, but I would think it to be lower once the pressure is stable since the turbo itself will provide some scavenging effect once spun up.

Turbocharger will never cause any scavenging compared to a NA engine, it is always a restriction in the exhaust path.

The amount of back pressure depends on the A/R of the turbine housing and the manifold design. Would be interesting to measure it, changing overlap if you have higher manifold than boost pressure can cause issues with residuals and can ruin any gains you might otherwise get from it.

To the OP, blueprinting your engine is the only reasonable modification you should do to it, unless you REALLY know what you are working with. I believe GAMI injectors are pretty much just that, "blueprinted" injectors.

 

[Tony_Scarpelli]

If I have this right?

Porting and polishing are to help with the distribution of the atomized fuel particles within each cylinder as well as the exhaust and with modern casting it is not required anymore.

Blue printing or balancing means to balance as close as possible the same amount of fuel delivered to each cylinder so they maintain a close CHT/EGT so the engine can be run more efficiently without risk of excessive heat or dentenation (particularly on the Lean side of Peak).

Balance the prop to reduce vibration against wear and tear on everything including the ride?

Engine analyzers monitor CHT and EGT which is more important for running LOP?

 

[Henning]

If I have this right?

Porting and polishing are to help with the distribution of the atomized fuel particles within each cylinder as well as the exhaust and with modern casting it is not required anymore.

Blue printing or balancing means to balance as close as possible the same amount of fuel delivered to each cylinder so they maintain a close CHT/EGT so the engine can be run more efficiently without risk of excessive heat or dentenation (particularly on the Lean side of Peak).

Balance the prop to reduce vibration against wear and tear on everything including the ride?

Engine analyzers monitor CHT and EGT which is more important for running LOP?

Balancing also includes balancing the reciprocating/rotating masses. Blue printing is getting all the dimensions to be what they should be, that's the machine work like line boring and and surfacing. Getting fuel flows to balance is something I consider more as "tuning".

Both CHT and EGT are important. EGT tells you where you are in the LOP/ROP mixture range (exact temp not crucial, more of a comparison to peak wherever that may fall) CHT lets you know the effects of that with regards to structural integrity of the cyl/head also gives you a clue as to your margin against detonation.