90mm LSX+Supercharger
"less boost (back pressure) would make more HP due to more flow AND less temp increase..."
"Go to a smaller pulley and you will make more power to a point. Beyond a certain point you will not be able to overcome the density loss due to heat. Also, higher charge air temps promote pre-ignition and detonation. What if you are already at the point where you can no longer "pulley up" for reliable power?"
These responses nailed it.
If you don't improve the efficiency of the pump (the engine), then eventually you run into an issue... HEAT. Sure you can push a stock setup, look at how the GN guys do it. Raymer's approach on his Formula for his big numbers is the same approach. Run as high an octane as you can.
"Octane rating is a measure of how resistant gasoline is to premature detonation (knocking). It is measured relative to a mixture of isooctane (2,5-dimethylhexane) and n-heptane. So an 87-octane petrol has the same knock resistance as a 87% isooctane/ 13% heptane mixture. Petrol is typically separated from crude oil via distillation, so the mixture of the molecules in the resulting fuel is dependent on the oil used. Romania was a supplier of "light-sweet" crude oil, which, when distilled, resulted in a petrol with an 87 rating. 87 octane was the general benchmark for much of the world, and is the current standard rating for "normal" petrol in the US and Canada.
It might seem odd that fuels with higher octane ratings burn less easily, yet are generally considered more powerful. Using a fuel with a higher octane allows the engine to be run at higher compressions, and not have problems with knock. Compression is directly related to power, so engines using higher octane deliver more power, explaining the common misconception. Some high-performance engines are designed to operate at the higher compression levels associated with high octane numbers, and thus demand high-octane gasoline.
History
Lead additives
Because the mixture known as gasoline has a tendency to explode or "knock", lead additives were first blended with fuel in the 1920s, and continued through the 1980s. The most popular one was tetra-ethyl lead. However, with the recognition of the environmental damage caused by the lead, and the incompatibility of lead with catalytic converters, most countries are in the process of phasing out the sale of leaded fuel, and different additives to reduce knocking are now used. Among the most popular ones are aromatic ethers and methanol. There are also additives to reduce internal engine carbon buildups, to increase oxidation, and to allow easier starting in cold climates."
So if you take Rob's example of a stock motor on kill, I'm guessing he can push a stock engine with C16 (117 motor octane) to about 750rwhp.
Keep in mind that:
-C16 is $8 per gallon
-C16 is leaded and will kill factory 02 sensors
So you can pulley a motor "down" to make more boost, but the engine will become more detonation prone.
Counter example:
My 9:1 348ci engine is built for boost. I bet I only make 350rwhp n/a through my T400. But we've hit 746rwhp with 17 lbs of boost on 108 motor octane. On C16 I could hit probably 825rwhp throught the T400, or about 850-900 through an M6.
It's all relative.
I'd rather make 800rwhp with 15psi then with 20psi.
"Go to a smaller pulley and you will make more power to a point. Beyond a certain point you will not be able to overcome the density loss due to heat. Also, higher charge air temps promote pre-ignition and detonation. What if you are already at the point where you can no longer "pulley up" for reliable power?"
These responses nailed it.
If you don't improve the efficiency of the pump (the engine), then eventually you run into an issue... HEAT. Sure you can push a stock setup, look at how the GN guys do it. Raymer's approach on his Formula for his big numbers is the same approach. Run as high an octane as you can.
"Octane rating is a measure of how resistant gasoline is to premature detonation (knocking). It is measured relative to a mixture of isooctane (2,5-dimethylhexane) and n-heptane. So an 87-octane petrol has the same knock resistance as a 87% isooctane/ 13% heptane mixture. Petrol is typically separated from crude oil via distillation, so the mixture of the molecules in the resulting fuel is dependent on the oil used. Romania was a supplier of "light-sweet" crude oil, which, when distilled, resulted in a petrol with an 87 rating. 87 octane was the general benchmark for much of the world, and is the current standard rating for "normal" petrol in the US and Canada.
It might seem odd that fuels with higher octane ratings burn less easily, yet are generally considered more powerful. Using a fuel with a higher octane allows the engine to be run at higher compressions, and not have problems with knock. Compression is directly related to power, so engines using higher octane deliver more power, explaining the common misconception. Some high-performance engines are designed to operate at the higher compression levels associated with high octane numbers, and thus demand high-octane gasoline.
History
Lead additives
Because the mixture known as gasoline has a tendency to explode or "knock", lead additives were first blended with fuel in the 1920s, and continued through the 1980s. The most popular one was tetra-ethyl lead. However, with the recognition of the environmental damage caused by the lead, and the incompatibility of lead with catalytic converters, most countries are in the process of phasing out the sale of leaded fuel, and different additives to reduce knocking are now used. Among the most popular ones are aromatic ethers and methanol. There are also additives to reduce internal engine carbon buildups, to increase oxidation, and to allow easier starting in cold climates."
So if you take Rob's example of a stock motor on kill, I'm guessing he can push a stock engine with C16 (117 motor octane) to about 750rwhp.
Keep in mind that:
-C16 is $8 per gallon
-C16 is leaded and will kill factory 02 sensors
So you can pulley a motor "down" to make more boost, but the engine will become more detonation prone.
Counter example:
My 9:1 348ci engine is built for boost. I bet I only make 350rwhp n/a through my T400. But we've hit 746rwhp with 17 lbs of boost on 108 motor octane. On C16 I could hit probably 825rwhp throught the T400, or about 850-900 through an M6.
It's all relative.
I'd rather make 800rwhp with 15psi then with 20psi.
Launching!
Joined: Jul 2002
Posts: 202
Likes: 0
From: Sterling, VA
We've talked about how the intake can help power by allowing more gasses to be moved. How about the exhaust setup? How impactive is having higher flowing headers? In a turob based set up you'll also have the added restriction of the turbo. How does that play into the overall power generated by a turbo?
