Limitations of Tuning and Performance - Unsure if correct ?

[cinoaz]

I'm not a car guy per se, I understand the theories of engine performance but not sure if my conclusions are correct. Just some corrections from the experts would be welcomed

If the volume of a cylinder is fixed (i.e. we don't increase cylinder size) and the stroke of a piston is fixed thus the compression ratio inside the engine remains constant, so for the Stinger V6 that is 10:1 ratio using atmospheric pressure.

To increase performance in this scenario, the only variable the engine has if everything else remains unchanged is increasing the volume of Air in the cylinder, thus increasing its compression ratio by exceeding atmospheric pressure. By increasing the volume however, this has the effect of heating the air along with the added compression heats the air even more. The heating of this air due to increased volume and compression, depending on the ambient temperature to begin with, may heat the air to the ignition point of the fuel, thus causing knock (premature detonation).

The goal of the intercooler is to try to lower the temperature of the ambient air to provide more headroom for internal temperature of the air in the cylinder to avoid premature detonation. A second option is to use a higher quality fuel, a higher octane, that detonates at a higher temperature thus preventing knock. A third option is to inject a cooling agent, like Water Injection, to try to reduce the temperature of the air so the fuel won't detonate.

In the end, it's a game of trying to shove higher volumes of air into a cylinder without it reaching the detonation point of the fuel being used and for the most part that's what all these tuning products try to do, in some way to push that sweet spot where you get the most volume of air but keep the temperature below detonation point of the fuel.

There is, however, a limit to the volume of air in a cylinder as the compression ranges could reach a point the internal components are not designed to handle and overstress the components to failure. In addition, if given limitless volume, the fuel system may not be able to add enough fuel, as the system has exceeded its capability to properly add sufficient fuel to the increased volume of air. So there is a point, given stock components, that you can increase one thing all you want but are limited by the secondary item in the system?

Is this then correct, that the major change in production of torque and horsepower for stock engines is this balancing act on how best one pushes the volume of air in the cylinder to stay below the detonation level of the fuel and how close one comes to reaching the failure point of the components based on the increased volume, above atmospheric pressure (PSI of the turbos) in the compression and explosion strokes while still within the range of the fuel system to keep up with the increased volumes?

 

[rpoffen]

One factor also to include is that many engines now use direct injection. This allows the gas to be injected closer to TDC of the piston stroke to avoid pre-ignition of the gas/air mixture as it would be for conventional (pre cylinder) fuel delivery.

 

[Devin]

Reducing losses is also an acceptable way to increase performance. This is the only reason intake and exhaust mods do anything.

 

[JSolo]

The 3.3 uses an air cooled intercooler correct? What if the intercooler was water/liquid cooled like it is on the 2.5T. That should yield more headroom for additional compression, yes?

 

[rpoffen]

The 3.3 uses an air cooled intercooler correct? What if the intercooler was water/liquid cooled like it is on the 2.5T. That should yield more headroom for additional compression, yes?

Yes, it is a Front Mounted InterCooler (FMIC).
There are certain advantages to a liquid cooled one, such as the ability to have it be closer to the intake so you don’t have heating in the long charge pipe after the FMIC.
It does add complexity including a separate cooling system with radiator, pump, coolant, etc. Not practical to retrofit I imagine.
For full drag racing purposes, you will see that it is common to ice down the intercooler before the run.

 

[byebyeSTI]

The 3.3 uses an air cooled intercooler correct? What if the intercooler was water/liquid cooled like it is on the 2.5T. That should yield more headroom for additional compression, yes?

for short periods of time , they work well but when they get heat soaked its over , and your in a worse position than an air to air , good for drag racing or small displacement engines , on our cars you would need 1 core per side and a very large heat exchanger to keep things cool ,

 

[oddball]

Right, it's all trades. Generally, higher output results in worse manners in non-high-performance situations. e.g., roll back 20 years, a 700 HP motor would idle at 1,500 RPM and would shake like an earthquake while doing it. Recent innovations, especially variable cam timing, allows an engine to have different performance characteristics at different points. But, there's still limits to how far that can go.
Valve timing and max lift has a tremendous impact on the volumetric efficiency (VE) of the engine. Naturally aspirated engines can actually get a VE greater than 1 when perfectly designed! That's why the solenoid driven valves in R&D by Koeniggsegg is so cool. And permanently "5 years away".

The easiest answer right now is to increase VE via forced induction. Computer controlled ignition timing and fuel injection makes this much easier than it was in decades past. Even then, there are trades. Turbo size is a big trade space. Bigger turbos can move more air, but they are physically larger so they take more energy to spool up. Smaller turbos spool faster, but physically saturate sooner. Superchargers, too. Bigger superchargers take more energy to drive - the blower on top fuel engines take several hundred HP to turn just by themselves!

There's also mechanical limits. Every part of the engine has a breaking point. Go too far and stuff will start breaking. Obvious things like pistons, rods, block webbing - but also stuff like losing oil film on the bearings, causing valve seats to drop, valves to seize, turbo parts to break, etc. Same for the transmission, driveshaft, differential(s), axles, etc. Then there's also traction - no point having 1,000 HP if you can only get 500 to the pavement.

Air to water intercoolers are interesting because you can do other fun tricks, like cool the water using your A/C system (a la Hellcat). But they get real complicated real fast and IMO it's harder to get equivalent efficiency to a traditional air/air intercooler. Normally these are seen where packing prevents an air/air intercooler, like an intake mounted supercharger. And don't forget, all you've done is move the heat into some water. Gotta get the heat out of the water.

 

[Aarvix]

Tell that to BMW.

The M cars use air-to-water intercoolers.

 

[rpoffen]

Right, it's all trades. Generally, higher output results in worse manners in non-high-performance situations. e.g., roll back 20 years, a 700 HP motor would idle at 1,500 RPM and would shake like an earthquake while doing it. Recent innovations, especially variable cam timing, allows an engine to have different performance characteristics at different points. But, there's still limits to how far that can go.
Valve timing and max lift has a tremendous impact on the volumetric efficiency (VE) of the engine. Naturally aspirated engines can actually get a VE greater than 1 when perfectly designed!

Exactly. Look at the NHRA Pro Stock class. They essentially use factory engine blocks, but the heads especially are highly modified. They use gas, no enhancements like nitrous, no forced induction, but still make up to 1500HP.

 

[RM7]

for short periods of time , they work well but when they get heat soaked its over , and your in a worse position than an air to air , good for drag racing or small displacement engines , on our cars you would need 1 core per side and a very large heat exchanger to keep things cool ,

How many air cooled intercooler cars have you owned? I find this to be the complete opposite. The air to air intercoolers only really work when you are moving forward and they heat sink relatively easily at slower speeds or with less airflow (like idling on a hot day, etc.). "Airflow" would reverse on my WRX at a stop, hot air from the engine, trans, hood, would then move up through the intercooler and out the vent at a stop, moving forward would fix this, but it was especially susceptible to heat sink. Front mounts are better, but no airflow means no cooling. In my understanding, the water to air benefit is that it won't heat soak at slower speeds/idling and the disadvantage is the increased complexity.

 

[RM7]

And don't forget, all you've done is move the heat into some water. Gotta get the heat out of the water.

Water's specific heat capacity is 4200 Jkg-1K-1 and Air's is 993 Jkg-1K-1 therefore water has 4.23 times more specific heat capacity. Running it with a motor and fan like a radiator gets the heat out of the water, even when standing still.

 

[byebyeSTI]

Tell that to BMW.

The M cars use air-to-water intercoolers.

true just like audi on there 3.0 supercharged and the new b9 turbo motors use air to water / also most mercedes benz do this as well on turbo cars , after modding my s4 , i had significant heat soak issues with the stock heat exchanger , i had to upgrade the core and the pump , also separated the intercooler water from the engine coolant , they use the same system to cool the charge air , so my charge air cooler had a base line of 196 degrees all the time , with i divided the 2 it was night and day . a big air to air is the best option

 

[byebyeSTI]

How many air cooled intercooler cars have you owned? I find this to be the complete opposite. The air to air intercoolers only really work when you are moving forward and they heat sink relatively easily at slower speeds or with less airflow (like idling on a hot day, etc.). "Airflow" would reverse on my WRX at a stop, hot air from the engine, trans, hood, would then move up through the intercooler and out the vent at a stop, moving forward would fix this, but it was especially susceptible to heat sink. Front mounts are better, but no airflow means no cooling. In my understanding, the water to air benefit is that it won't heat soak at slower speeds/idling and the disadvantage is the increased complexity.

plenty and i have built many turbo cars , subaru stuff is all different the IC is on top of the motor ! heat rises , air to water set ups work if they are designed right but when they get soaked its over. period , recovery time is 10x that of a air to air , also im taking this from a street car point of view
not drag racing , in a drag car fill up the ice box and go another round , not in a daily ,

 

[cinoaz]

Thanks for all the feedback. I'm thankful to learn so much from those that know, trying my best to keep my eyes and ears open and lips shut.

I always felt the Stinger should have been targeted around 420, instead of 360. I bought the first gen back in 2018 and just recently updated to a '22. 60 more HP and I think the car really takes on a totally different feel. So, with my '22, I plan on picking up the Mishimoto intercooler, Big Mouth intakes, JB4 tune with Map 2, maybe Map 3, if I can find E85 in my area.

I don't want to do a muffler delete or change the stock exhaust, I personally haven't seen the cost/performance work out. I was hoping to hit 60hp bump, trying to figure out what is possible and what isn't. Just trying to stay bolt on changes, don't want to start digging into the core.

 

[rpoffen]

Thanks for all the feedback. I'm thankful to learn so much from those that know, trying my best to keep my eyes and ears open and lips shut.

I always felt the Stinger should have been targeted around 420, instead of 360. I bought the first gen back in 2018 and just recently updated to a '22. 60 more HP and I think the car really takes on a totally different feel. So, with my '22, I plan on picking up the Mishimoto intercooler, Big Mouth intakes, JB4 tune with Map 2, maybe Map 3, if I can find E85 in my area.

I don't want to do a muffler delete or change the stock exhaust, I personally haven't seen the cost/performance work out. I was hoping to hit 60hp bump, trying to figure out what is possible and what isn't. Just trying to stay bolt on changes, don't want to start digging into the core.

Check into the BMS 450hp kit. Includes intakes, JB4, plugs, etc.

 

[cinoaz]

Check into the BMS kit. Includes intakes, JB4, plugs, etc.

Yep, exactly the kit I was going to install. I'm not a fan of reprogramming the stock ECU, still would like to try to keep factory service for as long as I can.

 

[General_Vodka]

Yep, exactly the kit I was going to install. I'm not a fan of reprogramming the stock ECU, still would like to try to keep factory service for as long as I can.

Get an ecu tune if you are worried about the dealer. Much easier to hide in my opinion. I even recall Tork claiming that they found out where the ECU tamper count is. Then again I don't have a warranty anymore lol, I am the warranty. Kia is happy to work on my car, as long as I pay for it. Plenty of people here have been successful in getting work down even with a piggyback but your mileage may vary. FYI the best bang for buck path is full bolt on with meth.

 

[RM7]

plenty and i have built many turbo cars , subaru stuff is all different the IC is on top of the motor ! heat rises , air to water set ups work if they are designed right but when they get soaked its over. period , recovery time is 10x that of a air to air , also im taking this from a street car point of view
not drag racing , in a drag car fill up the ice box and go another round , not in a daily ,

I don't think that's how air to water setups work, they are either using the radiator fan or have their own fan and it very much much prevents heat-soak, in the same way your engine cooling system prevents your engine from overheating. If you can manage to overwhelm these, you are dealing with some serious hot temps and racing is going to suck for many other reasons, lots of stuff overheating on the car, trans, etc. A big front mount air to air is good as long as you are moving forward, but again, at slow speeds or stopped, there is no airflow.

 

[byebyeSTI]

I don't think that's how air to water setups work, they are either using the radiator fan or have their own fan and it very much much prevents heat-soak, in the same way your engine cooling system prevents your engine from overheating. If you can manage to overwhelm these, you are dealing with some serious hot temps and racing is going to suck for many other reasons, lots of stuff overheating on the car, trans, etc. A big front mount air to air is good as long as you are moving forward, but again, at slow speeds or stopped, there is no airflow.

This IS how air to waters work . There is rarely a fan set up on them , unless you add one . did you forget the part in my response that I HAVE built many air to water set ups in a bunch of different cars , and have been a ase master tech for over 25 years . also part of the Porsche le mans race team as a tech . ? i understand what you are saying but you have no real experience to back it up , air to water is a great idea for some applications , just not our cars unless its a straight drag car , is what im saying

 

[oddball]

I don't think that's how air to water setups work, they are either using the radiator fan or have their own fan and it very much much prevents heat-soak, in the same way your engine cooling system prevents your engine from overheating. If you can manage to overwhelm these, you are dealing with some serious hot temps and racing is going to suck for many other reasons, lots of stuff overheating on the car, trans, etc. A big front mount air to air is good as long as you are moving forward, but again, at slow speeds or stopped, there is no airflow.

That radiator fan that does all the heavy work for the engine radiator is the same fan that does all the heavy work for the air-to-air intercooler. So that part of the argument doesn't work real well.

It's all about packaging. What packaging works for the specific build? Air to water intercoolers are much smaller because the water can absorb the heat effectively in a small intercooler compared to air-to-air. Great! Now it's back to a traditional radiator to get the heat out of the water.
But you have the plumbing, extra radiator, pump, reservoir, etc. And if you're nuts like my buddy, you have the separate refrigerant cool box, extra A/C lines, even more plumbing, Y switches, etc. But in his case it's a supercharger on a 4.6, so it's gotta be in the valley and - surprise! - he was having heat soak in the summer so we added the cool box.

air to water isn't inherently better than air to air. And vice versa. They're just different.