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shay2nak
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So, the 5 hp gain in the dyno translates to how much horsepower at the crank? 6? 196 hp?


So the 164.8 hp is RW HP and the usual manufactuerer's HP rating (like Elise's 190hp) is crank HP, right?

thanks.
 

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Yes on all counts, except for the 196 peak. Lotus claims 189 HP of peak HP, so it would be 195.
 

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>>>I read your post on the intake tests you did, but I'm still willing to test out a cold air intake that shinoo offers. If it hurts performance I'd just take it off. No harm in trying it out. <<<

By all means try stuff out. I'm just letting you know what some have already noticed with intakes on the same motor. Not all of the intakes lose in the lower RPMs but some of them sure did. All gained in the midrange and top end. In my case I'll be staying stock although I do have a K&N panel air filter loaded into the factory box in lieu of the Toyota paper filter.
 

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I wonder now how much more power gain could we get if we fit the Reverie Airbox.

I'll be waiting the Airbox to find the way to my garage, and will dyno test it!
:D
 

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Xfactor,
Do you know what fuel you were using at the time. Brand would be nice but more importantly what octane rating?
Had mine dynoed (with a dynojet) on saturday. I put the QS on yesterday. I will dyno that at my next oppurtunity. We can only get 91 octane here at the pump but I think I will also do a dyno run with 93 and if that is substantially more( I expect it to be) I may do another with 95 as no-one seems to know at what octane the engine produces no more gain.
As an FYI, I did this on my stock 2.5l Boxster. 91 octane produced 171rwhp, 93 octane made 185rwhp. Quite a difference!
 

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Discussion Starter · #26 ·
Hey adamant,

It was 93 octane, and I'm not positive on the brand (I'm not loyal to one company) probably shell or BP.

What were your dyno results? I would also think that altitude and temp would play a big role as well.
 

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I guess I put the results in the wrong thread. It was a dynojet and gives "corrected" results as did yours I think.
Mine was on 91 octane. I think our altitude steals about 20% of the power :(
Max power 164.6-166
Max torque 121.0-121.3
Almost identical values. My Elise has 1200miles now but I am sure it is still a little tight.
 

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adamant said:
We can only get 91 octane here at the pump but I think I will also do a dyno run with 93 and if that is substantially more( I expect it to be) I may do another with 95 as no-one seems to know at what octane the engine produces no more gain.
As someone else on the California octane diet, I too am very curious to know what the 'maximal octane' is for the stock tuning. Hopefully some datalogging from the ECU will shed some light on this as well.
 

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adamant said:
As an FYI, I did this on my stock 2.5l Boxster. 91 octane produced 171rwhp, 93 octane made 185rwhp. Quite a difference!
That is a pretty big difference. Too bad about the gas around here. :(
 

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If you have an event to go to and want a little extra boost, try adding 1 gallon of Tolulene to 9 gallons of 91/93 Octane. The Tolulene has 118-120 Octane rating. If you do the math, the result is 96 Octane gas with an aromatic hydrocarbon percentage of around 55%. I used to run this juice all the time in my modified A4. It reduces the chance of pre-detonation in high compression engines and allows the ECU to run a more advanced timing. Anyway, it equated to significant differences on the dyno and at the track. You can get a Gallon for $8 at sherwan Williams. I pick it up on sale and keep it handy.
 

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I've been running 87 octane since I bought mine. It seems to be running fine but it backfires every time I lift off the throttle. Just kidding, really.
 

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I've been running 87 octane since I bought mine. It seems to be running fine but it backfires every time I lift off the throttle. Just kidding, really.
rotfl rotfl rotfl

You could also add Naptha, Jet A, and Kerosene (really!) and raise your octane. They're all high octane 'light' fuels, and there's little difference between them. It will cost you engine life, though. I'll stick with 93 or 91 Octane.
 

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Adamant,
Higher octane fuel does not translate into more power without changing another one of the inputs in the engine. In fact, an engine actually produces more horsepower using a lower octane fuel right up until the point where the intake charge detonates.

Your increased horsepower figures were not a result of the higher octane gas unless something similar to the below list happened:
1. you increased the dynamic compression of the engine by adding boost or increasing the compression ratio.
2. you advanced the timing
3. you installed a higher heat range spark plug
4. your intake charge was more dense (either via a change in altitude or a change in the intake charge temp).

Lower octane fuel is more volatile, and therefore produces more power (given fixed inputs) up until the point where the fuel pre-ignites (aka detonates).
Best,
John



adamant said:
Xfactor,
Do you know what fuel you were using at the time. Brand would be nice but more importantly what octane rating?
Had mine dynoed (with a dynojet) on saturday. I put the QS on yesterday. I will dyno that at my next oppurtunity. We can only get 91 octane here at the pump but I think I will also do a dyno run with 93 and if that is substantially more( I expect it to be) I may do another with 95 as no-one seems to know at what octane the engine produces no more gain.
As an FYI, I did this on my stock 2.5l Boxster. 91 octane produced 171rwhp, 93 octane made 185rwhp. Quite a difference!
 

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JBurer said:
Adamant,
Higher octane fuel does not translate into more power without changing another one of the inputs in the engine. In fact, an engine actually produces more horsepower using a lower octane fuel right up until the point where the intake charge detonates.

Your increased horsepower figures were not a result of the higher octane gas unless something similar to the below list happened:
1. you increased the dynamic compression of the engine by adding boost or increasing the compression ratio.
2. you advanced the timing
3. you installed a higher heat range spark plug
4. your intake charge was more dense (either via a change in altitude or a change in the intake charge temp).

Lower octane fuel is more volatile, and therefore produces more power (given fixed inputs) up until the point where the fuel pre-ignites (aka detonates).
Best,
John

His point was that current ECUs can adapt to higher octane and advance the timing (#2). This is really a side affect of the "knock sensor" technology, which allows you to run lower octanes in a pinch. The results can be pretty significant. As with my M3 96 octane resulted in a net gain of 8rwhp, due simply to automatic advanced timing and better atomization.
 

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>>>His point was that current ECUs can adapt to higher octane and advance the timing (#2). This is really a side affect of the "knock sensor" technology, which allows you to run lower octanes in a pinch. The results can be pretty significant. As with my M3 96 octane resulted in a net gain of 8rwhp, due simply to automatic advanced timing and better atomization.<<<

Yes this can happen...but it gets tricky. Since the OBD2 learning process is involved. Lots of weird stuff can occur.
 

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Eyelise,I buy Toluene too, I can get 5gals here for $30. Have done for years. Once I discovered that Chevron use it to produce higher octane fuels. So anyone using "race gas" likely has a toluene component. For a few cars, I have proof that a modestly increased octane rating produces more power. I just thought I would share my results with others who are interested, I don't feel that I need to convince others though.
 

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To further what Stan said -
I am fairly certain the ECU learning process (aka open loop mode) only takes place during periods where the engine is at idle, constant throttle or light throttle inputs. The idea behind incorporating this technology was to increase gas mileage and reduce emissions to meet government regulations, not to increase power.

There are instances where sensors on the vehicle (a mass airflow sensor, for example) can adjust fuel delivery and timing to compensate for differences in altitude and boost pressure... but that's because the reading is taken prior to that cycle's combustion event. Even then, the baseline is a predefined map stored in the ECU and not feedback from an O2 sensor.

The O2 sampling is something obtained only after the fuel metered out for that cycle is combusted. These things happen very quickly, and the engine damage resulting from getting an adjustment wrong (from a defective O2 sensor, EFI, angle of the moon, etc) can be pretty catastrophic.

OEM's are profit-seeking enterprises. They aren't going to open themselves up to warranty claims simply to achieve a marginal gain in horsepower.

If Adamant were to do nothing but put 105 octane in his fuel tank, he is not going to see an increase in power beyond that which the OEM designed for the vehicle. His experience with increased power levels in his Boxter is likely due to his knock sensor detecting detonation and sending a signal to the ECU to retard the timing. This would explain the lower power levels while using lower octane gas.

Adamant, your car isn't a black box with fuel as an input. Please learn something about it before you pass on disinformation.
Best,
John


Stan said:
>>>His point was that current ECUs can adapt to higher octane and advance the timing (#2). This is really a side affect of the "knock sensor" technology, which allows you to run lower octanes in a pinch. The results can be pretty significant. As with my M3 96 octane resulted in a net gain of 8rwhp, due simply to automatic advanced timing and better atomization.<<<

Yes this can happen...but it gets tricky. Since the OBD2 learning process is involved. Lots of weird stuff can occur.
 

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Sorry, not disinformation, just FACTS. I just love it when people like you tell me how things work when clearly your point of view is incorrect.
Did I say I get more power with 105 Octane, NO. I am saying that I can get more power from 93 octane than 91 in more than one kind of vehicle.
Oh and try and be a little more condescending next time... please..:huh:
 

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The 8rwhp gain could be the result of quite a number of things. Sampling error of the dyno, air intake temps, spark plug condition, etc etc.

008 said:
His point was that current ECUs can adapt to higher octane and advance the timing (#2). This is really a side affect of the "knock sensor" technology, which allows you to run lower octanes in a pinch. The results can be pretty significant. As with my M3 96 octane resulted in a net gain of 8rwhp, due simply to automatic advanced timing and better atomization.
 

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Discussion Starter · #40 ·
He can't help it, he's from New York. :D


adamant said:
Sorry, not disinformation, just FACTS. I just love it when people like you tell me how things work when clearly your point of view is incorrect.
Did I say I get more power with 105 Octane, NO. I am saying that I can get more power from 93 octane than 91 in more than one kind of vehicle.
Oh and try and be a little more condescending next time... please..:huh:
 
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