Fuel Questions?

taimur.shah · Sat, Apr-21-2012, 12:53:02 PM

This is my understanding so far...please correct me if any of this is wrong.

In Europe we have 95-99 octane fuel (lets not argue which dealer is best). In the US you guys have 91-93 Octane fuel which has a lower power rating which is why bhp in the states is generally slightly lower. All of these fuels have a 8-10% ethanol content.

However a fuel with 15% ethanol (E85) seems to have a higher power rating which is why it is used in some super cars. E85 is generally cheaper but many cars need bigger fuel injectors to use it properly. So first question...Why does E85 give more power?..Is it due to compression ratios or that energy released from ethanol??? Also why does it need bigger injectors?

Also people talk about meth injections...I presume this has a coolant effect??! So why? how? and when? would you set your car up to use a meth injection?

mitch32 · Sat, Apr-21-2012, 04:03:00 PM

Loaded post you have there.

In USA and Europe they list octane numbers in different ways. Look up RON and MON on google. USA 91 is the same as European 94 octane.

E85 is hard to explain but firstly it has a higher octane rating and it's oxygenated. It's lambda though is lower, you need more fuel for the same amount of air. Bottom line is you make 30% more power on e85 especially when your forced induction.

Lastly Europe measures HP differently then North America, it's around 3% difference in power.

Wherryj · Mon, Apr-23-2012, 06:25:31 PM

Mitch is correct. The OP's post also fails to mention the fact that Octane is NOT a measure of power content. It is a measure of the fuel's resistance to premature detonation under pressure.

Higher octane does not necessarily mean higher power content. It does typically mean the capability of running higher compression without knocking/CPU advancing the timing.

SYT_Shadow · Mon, Apr-23-2012, 10:56:05 PM

[QUOTE=taimur.shah;1065473448]which has a lower power rating which is why bhp in the states is generally slightly lower[QUOTE]

Mitch is correct. The difference between power ratings is due to the difference in units of measure. Both are exactly as fast regarless of what you're measuring it in.

Look up a physics table and you'll see the conversion from horsies to kW varies depending on metric or standard. That's the difference you see.

As power ratings assume a certain % of variation, manufacturers could in theory give the same numbers in Europe and the US, they just choose not to.

Personally I think it's stupid that the M3 is rated at a retarded 414hp here instead of a nice flat 420hp as in Europe

Sat, Apr-21-2012, 12:53:02 PM	#1
taimur.shah Registered User Join Date: Apr 2012 Posts: 2 Reputation: 0	Fuel Questions? This is my understanding so far...please correct me if any of this is wrong. In Europe we have 95-99 octane fuel (lets not argue which dealer is best). In the US you guys have 91-93 Octane fuel which has a lower power rating which is why bhp in the states is generally slightly lower. All of these fuels have a 8-10% ethanol content. However a fuel with 15% ethanol (E85) seems to have a higher power rating which is why it is used in some super cars. E85 is generally cheaper but many cars need bigger fuel injectors to use it properly. So first question...Why does E85 give more power?..Is it due to compression ratios or that energy released from ethanol??? Also why does it need bigger injectors? Also people talk about meth injections...I presume this has a coolant effect??! So why? how? and when? would you set your car up to use a meth injection?

Mon, Apr-23-2012, 06:25:31 PM	#3
Wherryj Registered User Join Date: May 2011 Posts: 148 In the garage: '03 HONDA S2000 '11 BMW M3 Reputation: 0 Location: Livermore	Re: Fuel Questions? Mitch is correct. The OP's post also fails to mention the fact that Octane is NOT a measure of power content. It is a measure of the fuel's resistance to premature detonation under pressure. Higher octane does not necessarily mean higher power content. It does typically mean the capability of running higher compression without knocking/CPU advancing the timing.

Mon, Apr-23-2012, 10:56:05 PM	#4
SYT_Shadow Piraña Powered Join Date: Oct 2009 Posts: 1,343 Reputation: 0 Location: Westchester/Boston/Windham	Re: Fuel Questions? [QUOTE=taimur.shah;1065473448]which has a lower power rating which is why bhp in the states is generally slightly lower[QUOTE] Mitch is correct. The difference between power ratings is due to the difference in units of measure. Both are exactly as fast regarless of what you're measuring it in. Look up a physics table and you'll see the conversion from horsies to kW varies depending on metric or standard. That's the difference you see. As power ratings assume a certain % of variation, manufacturers could in theory give the same numbers in Europe and the US, they just choose not to. Personally I think it's stupid that the M3 is rated at a retarded 414hp here instead of a nice flat 420hp as in Europe

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Sat, Apr-21-2012, 04:03:00 PM	#2
mitch32 Registered User Join Date: Apr 2012 Posts: 1 Reputation: 0	Loaded post you have there. In USA and Europe they list octane numbers in different ways. Look up RON and MON on google. USA 91 is the same as European 94 octane. E85 is hard to explain but firstly it has a higher octane rating and it's oxygenated. It's lambda though is lower, you need more fuel for the same amount of air. Bottom line is you make 30% more power on e85 especially when your forced induction. Lastly Europe measures HP differently then North America, it's around 3% difference in power.