aluminator with a supercharger

[Jackson1320]

I just meant compression wise. Even with my combo if I had to go thru the short block I would spend the little extra on Something like manly rods and pistons and a ring pack designed for boost. If its apart anyway might as well.

That’s kinda one of the reasons built engines don’t last. We install some stronger parts but not all of the weak links get replaced. Then 90% of people or shops reuse parts. An aluminator is all new so nothing half wore out already

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[IamCDNJosh]

The Aluminator is also designed for FI in mind. Rather than a standard coyote where an SC & tune is adapted to work around the high CR.

 

[Jackson1320]

The Aluminator is also designed for FI in mind. Rather than a standard coyote where an SC & tune is adapted to work around the high CR.

Most aluminator engines are stock compression. Stock everything but rods and pistons

 

[WhinRR]

First of all, it OBVIOUSLY doesn’t take 10 psi to overcome 2 numbers of compression. More like 3-4 psi. So if we’re talking 9/1 at 18 psi vs 11/1 at 15 psi, they will make roughly the same power but the 9/1 18 psi combination will have lower chance of detonation, lower peak cylinder pressure (Pmax), and lower peak stresses on the components. Ring leakage will be similar because average cylinder pressure is unchanged.

Wouldn't an increase in temp from higher boost increase detonation? Heat is a byproduct of the compression of air and both adding boost and increasing compression ration accomplish compression of air. Increasing boost you are adding hotter air into a hot area (cylinder) leading to more unstable conditions=detonation. With higher compression, the air is compressed as the piston moves up leading to heat that is building making it more stable during this period (compared to boosted cylinder pressure/heat) until that cylinder is ready to "fire" and push piston down.
-Late night thoughts

 

[Jackson1320]

Wouldn't an increase in temp from higher boost increase detonation? Heat is a byproduct of the compression of air and both adding boost and increasing compression ration accomplish compression of air. Increasing boost you are adding hotter air into a hot area (cylinder) leading to more unstable conditions=detonation. With higher compression, the air is compressed as the piston moves up leading to heat that is building making it more stable during this period (compared to boosted cylinder pressure/heat) until that cylinder is ready to "fire" and push piston down.
-Late night thoughts

I good intercooler should keep iat down. My procharger never has iat’s more than 10 degrees over ambient. The air rushing in is cooling down the cylinder in both applications. Also NA cars run hotter plugs and so retain some heat there. So before the compression stroke I would call it a wash

 

[engineermike]

Wouldn't an increase in temp from higher boost increase detonation? Heat is a byproduct of the compression of air and both adding boost and increasing compression ration accomplish compression of air. Increasing boost you are adding hotter air into a hot area (cylinder) leading to more unstable conditions=detonation. With higher compression, the air is compressed as the piston moves up leading to heat that is building making it more stable during this period (compared to boosted cylinder pressure/heat) until that cylinder is ready to "fire" and push piston down.

Many points in your post are correct. For instance, higher boost does result in high charge temp. However, in order to determine how likely knock is, you have to look at the conditions in the cylinder just before and during combustion. For starters, understand that there are many factors that affect knock, but they are chiefly mixture pressure, temperature, and octane. Let's take my 2 combinations from above and demonstrate a [drastically simplified] model:

11/1 compression at 15 psi: The air will be 190+ deg F leaving the supercharger. Assume the intercooler pulls 100 deg F out, so the manifold charge temp will be about 90 deg F. Assume conditions at BDC are the same 15 psi and 90 deg F. When you compress this 11/1 volume ratio, the resulting pressure and temperature are 840 psi and 970 deg F.

9/1 compression at 18 psi: The air will be 210+ deg F leaving the supercharger, as you predicted. Assume the intercooler pulls 100 deg F out, so the manifold charge temp will be about 110 deg F. Assume conditions at BDC are the same 18 psi and 110 deg F, both of which are higher than the above case. However, when you compress this 9/1 volume ratio, the resulting pressure and temperature are 700 psi and 900 deg F, a reduction of 140 psi and 70 deg F. This clearly moves you in a favorable direction from a detonation and engine stress standpoint.

 

[80FoxCoupe]

I good intercooler should keep iat down. My procharger never has iat’s more than 10 degrees over ambient. The air rushing in is cooling down the cylinder in both applications. Also NA cars run hotter plugs and so retain some heat there. So before the compression stroke I would call it a wash

You talking air to air IC? 10deg over ambient while cruising sure, def not on a pull, absolutely not on a quarter mile pass.

 

[80FoxCoupe]

Many points in your post are correct. For instance, higher boost does result in high charge temp. However, in order to determine how likely knock is, you have to look at the conditions in the cylinder just before and during combustion. For starters, understand that there are many factors that affect knock, but they are chiefly mixture pressure, temperature, and octane. Let's take my 2 combinations from above and demonstrate a [drastically simplified] model:

11/1 compression at 15 psi: The air will be 190+ deg F leaving the supercharger. Assume the intercooler pulls 100 deg F out, so the manifold charge temp will be about 90 deg F. Assume conditions at BDC are the same 15 psi and 90 deg F. When you compress this 11/1 volume ratio, the resulting pressure and temperature are 840 psi and 970 deg F.

9/1 compression at 18 psi: The air will be 210+ deg F leaving the supercharger, as you predicted. Assume the intercooler pulls 100 deg F out, so the manifold charge temp will be about 110 deg F. Assume conditions at BDC are the same 18 psi and 110 deg F, both of which are higher than the above case. However, when you compress this 9/1 volume ratio, the resulting pressure and temperature are 700 psi and 900 deg F, a reduction of 140 psi and 70 deg F. This clearly moves you in a favorable direction from a detonation and engine stress standpoint.

@engineermike , it is my observation that the points you bring up are to emphasize reliability at a specific power output. Which is why so many OEM combos are pointed out. One thing that should be noted, is that many are limited by the FI system used.

Your example above explains lower CR / higher boost, versus higher CR / lower boost. Both with the same output, lower CR setup being more reliable/safer. In a situation where the FI system is maxed out such as turbo(s) out of efficiency range or blower maxed or pulley limited, the higher CR combo will make more power. Of course at the cost of reliability to an extent.

Many here want to make as much power as possible with the FI system they have in place. We have the ability to run all FI options available with somewhat higher CR. Options such as cam timing, direct injection, methanol inj, e85, race gas, intercoolers etc.

Your approach is ideal if one is planning to make a specific amount of power in a boosted application, as safely as possible. But many are limited by the FI system, in that instance the higher CR setup is the way to go to maximize output.

 

[Meatball]

Many points in your post are correct. For instance, higher boost does result in high charge temp. However, in order to determine how likely knock is, you have to look at the conditions in the cylinder just before and during combustion. For starters, understand that there are many factors that affect knock, but they are chiefly mixture pressure, temperature, and octane. Let's take my 2 combinations from above and demonstrate a [drastically simplified] model:

11/1 compression at 15 psi: The air will be 190+ deg F leaving the supercharger. Assume the intercooler pulls 100 deg F out, so the manifold charge temp will be about 90 deg F. Assume conditions at BDC are the same 15 psi and 90 deg F. When you compress this 11/1 volume ratio, the resulting pressure and temperature are 840 psi and 970 deg F.

9/1 compression at 18 psi: The air will be 210+ deg F leaving the supercharger, as you predicted. Assume the intercooler pulls 100 deg F out, so the manifold charge temp will be about 110 deg F. Assume conditions at BDC are the same 18 psi and 110 deg F, both of which are higher than the above case. However, when you compress this 9/1 volume ratio, the resulting pressure and temperature are 700 psi and 900 deg F, a reduction of 140 psi and 70 deg F. This clearly moves you in a favorable direction from a detonation and engine stress standpoint.

Does the in-cylinder compression multiply the iat2 or add to it? I’m sure I’m over-simplifying but the temp after compression is so much higher it makes it seem like the pre-compression temp differences would not be important unless it’s multiplied...

 

[engineermike]

@engineermike , it is my observation that the points you bring up are to emphasize reliability at a specific power output. Which is why so many OEM combos are pointed out. One thing that should be noted, is that many are limited by the FI system used.

Your example above explains lower CR / higher boost, versus higher CR / lower boost. Both with the same output, lower CR setup being more reliable/safer. In a situation where the FI system is maxed out such as turbo(s) out of efficiency range or blower maxed or pulley limited, the higher CR combo will make more power. Of course at the cost of reliability to an extent.

Many here want to make as much power as possible with the FI system they have in place. We have the ability to run all FI options available with somewhat higher CR. Options such as cam timing, direct injection, methanol inj, e85, race gas, intercoolers etc.

Your approach is ideal if one is planning to make a specific amount of power in a boosted application, as safely as possible. But many are limited by the FI system, in that instance the higher CR setup is the way to go to maximize output.

First, if you read the post I quoted in my response, I was specifically responding to WhinRR's question about detonation.

You are correct that if you are airflow limited and want more power, then higher CR will extract more power from a given airflow, at the expense of component stress and tendency to knock. However, I don't believe the OP's Vortech is up against its flow limit. I was actually under the impression that very few Coyote owners find the limit of their blowers and turbos.

 

[80FoxCoupe]

First, if you read the post I quoted in my response, I was specifically responding to WhinRR's question about detonation.

You are correct that if you are airflow limited and want more power, then higher CR will extract more power from a given airflow, at the expense of component stress and tendency to knock. However, I don't believe the OP's Vortech is up against its flow limit. I was actually under the impression that very few Coyote owners find the limit of their blowers and turbos.

Your response about detonation was addressed by the acknowledgement that the lower CR set was more reliable/safer. I just wanted to point out that your position is valid for the majority, but in a max effort scenario more CR will produce more power.

I wasn't honing in specifically on the OP vortech setup, i realize he is not set on kill. Your technical contribution is greatly appreciated, but is conveyed that the lower CR is best indefinitely. Other scenarios lend itself to more CR with boost being ideal (airflow limited and off boost performance). I know that your combo will be well thought out and hope everyone else will be as diligent, despite their goals.

 

[engineermike]

Does the in-cylinder compression multiply the iat2 or add to it? I’m sure I’m over-simplifying but the temp after compression is so much higher it makes it seem like the pre-compression temp differences would not be important unless it’s multiplied...

The in-cylinder compression multiplies IAT2/MCT, but it multiplies the absolute temperature (deg Rankine). For instance, and again this is grossly simplified for demonstration purposes: T2 = (90+460) x ((840+14.7)/(15+14.7))^((1.4-1)/1.4) - 460

The compression ratio is much more influential over the post-compression temperature than the IAT2/MCT. Also interesting is that the boost pressure, once intercooled, does not affect the post-compression temperature at all.

 

[engineermike]

....but is conveyed that the lower CR is best indefinitely. Other scenarios lend itself to more CR with boost being ideal (airflow limited and off boost performance)...

There are definitely disadvantages to lowering the compression ratio, fuel economy being on of them. It's likely the tune will need a bit of work as well since all the Coyote tunes use high compression torque models and spark tables as a baseline. Some might also run into challenges with the supercharger drive system when attempting the necessary higher boost levels.

I've spent the last 6 months fiddling with my 12/1 10 psi Gen3 trying to extract every bit of power possible on 93 and keep hitting knock as the road block. I've learned a ton in doing so, but unfortunately most of the increases I've found happen below 5000 rpm. I actually have a Gen3 short block on the stand set up at 11/1, which is still a little higher than I'd like. I just don't know if it's worth it to swap out the pistons in order to get down to 10 or 10.5.

 

[Meatball]

The in-cylinder compression multiplies IAT2/MCT, but it multiplies the absolute temperature (deg Rankine). For instance, and again this is grossly simplified for demonstration purposes: T2 = (90+460) x ((840+14.7)/(15+14.7))^((1.4-1)/1.4) - 460

The compression ratio is much more influential over the post-compression temperature than the IAT2/MCT. Also interesting is that the boost pressure, once intercooled, does not affect the post-compression temperature at all.

Interesting...so it's IAT2 (I take it -460 Rankine is abs zero?) times some factor related to the ratio of post-compression pressure / manifold pressure? Dumbing it down for me, how did you calculate the post-compression pressure...does it depend on manifold pressure and IAT2 as well as CR?

So is that claim I've heard a hundred times about intercooling increasing air density therefore power a bunch of nonsense? The SC will pump what it's going to pump regardless of density afterwards, so intercooling is really only for knock prevention (and more power through more aggressive timing)? Sorry for all the questions...

 

[80FoxCoupe]

The in-cylinder compression multiplies IAT2/MCT, but it multiplies the absolute temperature (deg Rankine). For instance, and again this is grossly simplified for demonstration purposes: T2 = (90+460) x ((840+14.7)/(15+14.7))^((1.4-1)/1.4) - 460

The compression ratio is much more influential over the post-compression temperature than the IAT2/MCT. Also interesting is that the boost pressure, once intercooled, does not affect the post-compression temperature at all.

That last sentence, did you mean post combustion?

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