Makes keeping an eye on the new EBDI engines being tested by GM in their 3500HD pickups worth it. These engines, 3.2L in size, are kicking out the same hp and torque as a 6.6L duramax diesel, and getting better mpg to boot! And all on E85. Ricardo, the UK engine designer, is working with GM on this engine design. Easy look up if anyone wants to read about it. Even a few you tube videos on the engine by the lead engineer at Ricardo.
DAVID LILES ETHAMAX - IS IT WORTH $1
- Thread starter chad8
- Start date
- Status
Originally Posted By: Hyde244
^ Why do you put 93 octane fuel into a high compression engine instead of 87 octane fuel?
Because you want to operate the engine at very high load levels. (such as severe acceleration, pulling heavy weight, or driving in very hot weather)
93 octane and 87 octane gasoline both carry the same BTU content. However, the different octane ratings will allow 93 octane to not pre-ignite in a high compression engine, allowing for an increase in performance. Modern cars do have anti-knock sensors, but computers will lag under heavy load demand.
Car Talk actually has a great section of their website devoted to this discussion: http://www.cartalk.com/content/premium-vs-regular-1
Same concept with ethanol and E85. Yes the BTU content is lower, but under heavy load ethanol would lead to less pre-ignition, and indeed increase performance of a high-compression engine, especially those that can operate on octane ratings above normal gasoline (93).
That being said, 99% of other driving conditions do not require high octane fuel, and 87 octane will do just fine.
Close but no cigar.
This idea will vary wildly by platform. Mfgrs use vastly different strategies, and while many times the hardware is similar its implementation can be very different.
Even software is an issue, as an update or correction by an aftermarket tuner can alter the characteristics of the system drastically.
Computers as used in MOST cars do not "lag" in their response to knock, as many modern piston designs are quite fragile under preignition loading and fracture easily above the top ring if detonated regularly. Generally the high performance tuned engine has sensors that are designed to protect it from low quality fuel, as mfgrs know the real world out there...
^ Why do you put 93 octane fuel into a high compression engine instead of 87 octane fuel?
Because you want to operate the engine at very high load levels. (such as severe acceleration, pulling heavy weight, or driving in very hot weather)
93 octane and 87 octane gasoline both carry the same BTU content. However, the different octane ratings will allow 93 octane to not pre-ignite in a high compression engine, allowing for an increase in performance. Modern cars do have anti-knock sensors, but computers will lag under heavy load demand.
Car Talk actually has a great section of their website devoted to this discussion: http://www.cartalk.com/content/premium-vs-regular-1
Same concept with ethanol and E85. Yes the BTU content is lower, but under heavy load ethanol would lead to less pre-ignition, and indeed increase performance of a high-compression engine, especially those that can operate on octane ratings above normal gasoline (93).
That being said, 99% of other driving conditions do not require high octane fuel, and 87 octane will do just fine.
Close but no cigar.
This idea will vary wildly by platform. Mfgrs use vastly different strategies, and while many times the hardware is similar its implementation can be very different.
Even software is an issue, as an update or correction by an aftermarket tuner can alter the characteristics of the system drastically.
Computers as used in MOST cars do not "lag" in their response to knock, as many modern piston designs are quite fragile under preignition loading and fracture easily above the top ring if detonated regularly. Generally the high performance tuned engine has sensors that are designed to protect it from low quality fuel, as mfgrs know the real world out there...
Originally Posted By: TiredTrucker
Makes keeping an eye on the new EBDI engines being tested by GM in their 3500HD pickups worth it. These engines, 3.2L in size, are kicking out the same hp and torque as a 6.6L duramax diesel, and getting better mpg to boot! And all on E85. Ricardo, the UK engine designer, is working with GM on this engine design. Easy look up if anyone wants to read about it. Even a few you tube videos on the engine by the lead engineer at Ricardo.
And if they run the same technology on gas, they'll get even better mileage to boot...
You simply cannot get away from chemistry and stoichiometry.
Look at the following chart...it might take a little math to work through the ideas, as it's in S.I. units as opposed to gut feel and feel good...rubbish pic, but the source is "INternal Combusion Engine Fundimentals" by J.B. Heywood, you might be able to find a scan on Google Books, or pull up his references from the bottom of the page.
One of the columns gives the available energy at stoichiometric mixture...alcohols lose to gas/diesel...then throw in Air/Fuel ratios and fuel density...alcohols lose to gas/diesel.
Ricardo Institute (and I'm not sure if you understand their origin, Sir Harry is one of my heros) are great, they will make a great solution...but simple chemistry says that if they get the thermal efficiency correct, and a power output, the same technology will give more miles on a gallon of gas...and we get back to ethanol standing meritoriuos only on cost per mile.
* For those interested, you can take the figures for either of the alky's, and working out from the latent heat of vaporisation (only available with carb or port injection), energy at stoichiometry, and Octane ratings why alky cars can make more power than gas...at double the fuel consumption (methanol).
Makes keeping an eye on the new EBDI engines being tested by GM in their 3500HD pickups worth it. These engines, 3.2L in size, are kicking out the same hp and torque as a 6.6L duramax diesel, and getting better mpg to boot! And all on E85. Ricardo, the UK engine designer, is working with GM on this engine design. Easy look up if anyone wants to read about it. Even a few you tube videos on the engine by the lead engineer at Ricardo.
And if they run the same technology on gas, they'll get even better mileage to boot...
You simply cannot get away from chemistry and stoichiometry.
Look at the following chart...it might take a little math to work through the ideas, as it's in S.I. units as opposed to gut feel and feel good...rubbish pic, but the source is "INternal Combusion Engine Fundimentals" by J.B. Heywood, you might be able to find a scan on Google Books, or pull up his references from the bottom of the page.
One of the columns gives the available energy at stoichiometric mixture...alcohols lose to gas/diesel...then throw in Air/Fuel ratios and fuel density...alcohols lose to gas/diesel.
Ricardo Institute (and I'm not sure if you understand their origin, Sir Harry is one of my heros) are great, they will make a great solution...but simple chemistry says that if they get the thermal efficiency correct, and a power output, the same technology will give more miles on a gallon of gas...and we get back to ethanol standing meritoriuos only on cost per mile.
* For those interested, you can take the figures for either of the alky's, and working out from the latent heat of vaporisation (only available with carb or port injection), energy at stoichiometry, and Octane ratings why alky cars can make more power than gas...at double the fuel consumption (methanol).
Just saw this product in my local closeout store for some great prices! $10 for 2.5 gallon jugs and $5 for a gallon. Looks like I may have to pass...
Last edited:
- Status
Similar threads
- Locked
- Locked