Turbo WHP and Octane rating for dyno
03-27-2006, 06:01 PM
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By injecting water, you are only taking up room that could otherwise be filled with fuel and O2 with an incombustable liquid that absorbs energy when it evaporates. You will loose hp unless you advance your timing, lean our your afr, or run more boost than you could without it.
Last edited by rkostolni; 03-27-2006 at 07:13 PM.
03-27-2006, 06:05 PM
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Originally Posted by coolingmist
That is absolutely un true. We have countless cars, SRT's, EVO's, 350Z Turbos, DSMs, etc that all gain HP just from putting the kit on.
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Last edited by PUR NRG; 05-01-2011 at 07:36 AM.
03-28-2006, 09:02 AM
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Originally Posted by PUR NRG
Just from putting the kit on? Or putting the kit on and retuning? I think you're being disingenuous here.
yes you will gain more HP from tuning with it. Most modern cars have ECUs that advance timing automatically from colder intake temps.
People on this forum can argue and dis-agree all they want. We know for a fact, we see it every day.
03-28-2006, 09:03 AM
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Originally Posted by rkostolni
By injecting water, you are only taking up room that could otherwise be filled with fuel and O2 with an incombustable liquid that absorbs energy when it evaporates. You will loose hp unless you advance your timing, lean our your afr, or run more boost than you could without it.
what you are forgetting is that most modern cars will advance the timing automatically because of the colder intake temps going into your engine.
I am NOT refering to Normally Aspirated cars, my statements refer to Turbo and Supercharged cars.
03-28-2006, 09:49 AM
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Originally Posted by rkostolni
By injecting water, you are only taking up room that could otherwise be filled with fuel and O2 with an incombustable liquid that absorbs energy when it evaporates. You will loose hp unless you advance your timing, lean our your afr, or run more boost than you could without it.
This guy went through the math and proofed it:
http://not2fast.wryday.com/thermo/wa...opt_mass.shtml
Originally Posted by MadDog
^ can you explain the science behind the assertion that adding water to the combustion cycle will add HP? IF that's true, I'm going to start adding a pint of water to my gas tank when I fill-up.
03-28-2006, 10:18 AM
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Posted by Richard Paul:
I was hoping not to have to be the one to reply here but..so no one else eh??
Zeuschel used water/meth on the Merlin race engines at Reno. This was 50/50 mix. BUT these were very highly supercharged race engines and also had 120+ fuel. I can't recall exactly how much boost they ran and if I did I'd have to kill you if I told. 40-50 psi might be in the ballpark.
The tune on these engines was so far beyond what Rolls Royce designed that they sent a telex saying GOOD LUCK. According to Rolls calculations Dave was running 3500 + HP.
The H2O/Meth injection was used to control detonation and a complex anolog system of metering it was built custom. Realize that we are talking a lot of liquid to carry around on a plane for the entire race. Therefore it was regulated to use during critical times. as pointed out by the turbo user above it was only effective when used in a system that would otherwise not be viable. Ricardo has a section on water injection and I havn't read it in 20 years I think he basicly calls out that it makes more power then if it were detonating but iif you could not detonate you'd make more power without it.
Don't forget while methonol has a much higher resistance to detonation it has half the BTU's. When in the presence of water it will obsorb same and really being used as a coolant. Put the fire out and it is cooler. But why did you start the fire in the first place? To get the heat and thus expansion to move the rotor. Ha, you thought I was about to say piston.
Zeuschel used water/meth on the Merlin race engines at Reno. This was 50/50 mix. BUT these were very highly supercharged race engines and also had 120+ fuel. I can't recall exactly how much boost they ran and if I did I'd have to kill you if I told. 40-50 psi might be in the ballpark.
The tune on these engines was so far beyond what Rolls Royce designed that they sent a telex saying GOOD LUCK. According to Rolls calculations Dave was running 3500 + HP.
The H2O/Meth injection was used to control detonation and a complex anolog system of metering it was built custom. Realize that we are talking a lot of liquid to carry around on a plane for the entire race. Therefore it was regulated to use during critical times. as pointed out by the turbo user above it was only effective when used in a system that would otherwise not be viable. Ricardo has a section on water injection and I havn't read it in 20 years I think he basicly calls out that it makes more power then if it were detonating but iif you could not detonate you'd make more power without it.
Don't forget while methonol has a much higher resistance to detonation it has half the BTU's. When in the presence of water it will obsorb same and really being used as a coolant. Put the fire out and it is cooler. But why did you start the fire in the first place? To get the heat and thus expansion to move the rotor. Ha, you thought I was about to say piston.
Last edited by rkostolni; 03-28-2006 at 10:21 AM.
03-28-2006, 10:48 AM
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rkostolni,
If air density goes up, the number of oxygen molecules in the combustion chamber goes up and so does power.
Intercooling done with an intercooler or done with water is essentially the same. If you believe it's bogus you might as well get rid of your intercooler and safe some weight.
You can argue that it to fill up a water tank is a pain in the neck and you can argue to install a larger intercooler instead, but you can't argue its effectiveness. Simple laws of physics nothing else.
If air density goes up, the number of oxygen molecules in the combustion chamber goes up and so does power.
Intercooling done with an intercooler or done with water is essentially the same. If you believe it's bogus you might as well get rid of your intercooler and safe some weight.
You can argue that it to fill up a water tank is a pain in the neck and you can argue to install a larger intercooler instead, but you can't argue its effectiveness. Simple laws of physics nothing else.
03-28-2006, 11:04 AM
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I've never used the stuff, so I don't know for sure whether you would benefit or not. I can only state what I've heard, being it is only beneficial if you are operating in condition where you would otherwise be detonating.
Intercooling is different than water injection because the water remains in the air stream after it has done its job.
Intercooling is different than water injection because the water remains in the air stream after it has done its job.
03-28-2006, 11:18 AM
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Water injection can be different than an intercooler, if some of the water evaporates in the combustion chamber and therefore cools the intake air during the compression cycle. Fuel can cool the intake charge as well, but it is 6 times less effective and too much fuel will lead to a power reduction.
Also, water vapor is already present in the air and gasoline converts to water and carbondioxide during the combustion.
But I do understand that waterinjection might not be quite as beneficial with low boost than with high boost applications.
Also, water vapor is already present in the air and gasoline converts to water and carbondioxide during the combustion.
But I do understand that waterinjection might not be quite as beneficial with low boost than with high boost applications.
03-28-2006, 12:27 PM
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^That's true. But in this case water is already vapor and therefore does reduce air density (= less power).
It's the phase change from liquid to gas that cools the intake charge and that does increase air density.
It's the phase change from liquid to gas that cools the intake charge and that does increase air density.
Last edited by globi; 03-28-2006 at 12:37 PM.
03-28-2006, 03:16 PM
#37
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I´m not running anything below Shell´s V-POWER in my car. It´s rated 99 octane here in sweden.
A guy did a dyno on his 8 using "normal" unleaded 95 octane (swedish octanes) VS 99 octane (swedish octane again) and "FOUND" about 20whp!!!
A guy did a dyno on his 8 using "normal" unleaded 95 octane (swedish octanes) VS 99 octane (swedish octane again) and "FOUND" about 20whp!!!
03-28-2006, 06:11 PM
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With the assumption of throwing on water injection and driving: (i.e. no tuning)
I realize that, but there's a reason high humidity results in lower HP. It takes up space, and with waters high specific heat, it absorbs considerable energy that could otherwise be used to move a piston or a rotor. In the case of spraying liquid water into the air, this problem will be even more pronounced, as it won't all evaporate.
So does the beneficial cooling effect on the air outweigh the above drawbacks? Personally, I suspect not, and I've read many articles saying that it does not. But, I cannot say for sure since I've never seen dyno results, never used it, or knew anyone who used it.
Although with more aggressive tuning then it surely will be beneficial.
Originally Posted by globi
^That's true. But in this case water is already vapor and therefore does reduce air density (= less power).
It's the phase change from liquid to gas that cools the intake charge and that does increase air density.
It's the phase change from liquid to gas that cools the intake charge and that does increase air density.
So does the beneficial cooling effect on the air outweigh the above drawbacks? Personally, I suspect not, and I've read many articles saying that it does not. But, I cannot say for sure since I've never seen dyno results, never used it, or knew anyone who used it.
Although with more aggressive tuning then it surely will be beneficial.
Last edited by rkostolni; 03-28-2006 at 06:13 PM.
03-29-2006, 12:48 PM
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Yes injecting liquid water almost always increases net air density. The air density lost by the room vapor takes is less than what is gained on air density by cooling the intake charge.
It's a physical fact.
As I said before this guy did the math and proofed it.
http://not2fast.wryday.com/thermo/w.../opt_mass.shtml
You can always try to find an error in his calculations, if you don't believe it.
If the injected water doesn't evaporate, it doesn't take up room because water takes 1700 times less space when it is in liquid form than when it is in gaseous form and liquid water is therefore neglectable.
And if you want to learn more about waterinjection here's a forum:
http://www.waterinjection.info/phpBB2/
It's a physical fact.
As I said before this guy did the math and proofed it.
http://not2fast.wryday.com/thermo/w.../opt_mass.shtml
You can always try to find an error in his calculations, if you don't believe it.
If the injected water doesn't evaporate, it doesn't take up room because water takes 1700 times less space when it is in liquid form than when it is in gaseous form and liquid water is therefore neglectable.
And if you want to learn more about waterinjection here's a forum:
http://www.waterinjection.info/phpBB2/
03-29-2006, 12:56 PM
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Also if you were to inject water into the combustion chamber after the ignition, it would cool down the gases in the chamber but it wouldn't reduce pressure. (And pressure and not temperature is what drives the piston). In fact it would even slightly increase pressure because steam takes 1700 times more room than liquid water.
RG just posted the 6 stroke concept, where this effect (1700 times more space) is taken advantage of.
http://www.autoweek.com/apps/pbcs.dl...THISWEEKSISSUE
RG just posted the 6 stroke concept, where this effect (1700 times more space) is taken advantage of.
http://www.autoweek.com/apps/pbcs.dl...THISWEEKSISSUE
03-30-2006, 09:40 AM
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Originally Posted by globi
As I said before this guy did the math and proofed [sic] it.
http://not2fast.wryday.com/thermo/w.../opt_mass.shtml
http://not2fast.wryday.com/thermo/w.../opt_mass.shtml
You mistakenly included the elipsis (sp?) in your link. It doesn't work...
03-30-2006, 12:06 PM
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03-30-2006, 10:41 PM
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Originally Posted by guitarjunkie28
for all you octane freaks, i've done 353whp on 87 octane with high (9.5) compression rotors.
03-31-2006, 04:16 PM
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Tuning is always important with high or low octane fuel with or without intercooling with or without high compression rotors and with or without water injection.
The optimal tuning on a boosted high compression engine with low octane will always result in less power than the optimal tuning on a boosted low compression engine with high octance fuel.
Renault was using water injection in their turbocharged F1 cars before it was banned. At that time (1983) fuel wasn't regulated (no octane limit), but they went with water injection anyway, even though this lead to a weight penalty since they had to carry a 12 litre water tank. If they could have gotten the same power with fuel tuning they would have done it. No race car engineer makes a system more complicated and heavier just for fun.
The optimal tuning on a boosted high compression engine with low octane will always result in less power than the optimal tuning on a boosted low compression engine with high octance fuel.
Renault was using water injection in their turbocharged F1 cars before it was banned. At that time (1983) fuel wasn't regulated (no octane limit), but they went with water injection anyway, even though this lead to a weight penalty since they had to carry a 12 litre water tank. If they could have gotten the same power with fuel tuning they would have done it. No race car engineer makes a system more complicated and heavier just for fun.
04-01-2006, 12:21 PM
#47
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i'm going for 400 on 87 with my next engine
The optimal tuning on a boosted high compression engine with low octane will always result in less power than the optimal tuning on a boosted low compression engine with high octance fuel.
that's partially true. the higher the compression, the more power, up until you run out of octane, THEN, you cram more air in there for the same combustion pressure, and the extra air is what gives the lower compression motors more power.
EX:
2 identical motors, except one has 9:1 compression, the other 10:1,
60-1 turbo, 6 psi...
the high comp engine wins here.
how about 15 psi?
they might be about equal because you'd have to pull so much timing out of the high-comp motor.
20 psi?
low compression is king (assuming pump gas and the high-comp motor couldn't go that high)
The optimal tuning on a boosted high compression engine with low octane will always result in less power than the optimal tuning on a boosted low compression engine with high octance fuel.
that's partially true. the higher the compression, the more power, up until you run out of octane, THEN, you cram more air in there for the same combustion pressure, and the extra air is what gives the lower compression motors more power.
EX:
2 identical motors, except one has 9:1 compression, the other 10:1,
60-1 turbo, 6 psi...
the high comp engine wins here.
how about 15 psi?
they might be about equal because you'd have to pull so much timing out of the high-comp motor.
20 psi?
low compression is king (assuming pump gas and the high-comp motor couldn't go that high)
04-01-2006, 03:56 PM
#48
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^True.
But, at least as far as I understand it: Tuning includes all factors that are adaptable and that does include boost pressure.
With optimal tuning I meant to optimize or max out all adaptable factors (fuel, boost pressure and ignition) in order to get maximum power.
The point is: If you say you'll get 400hp on 87 octance, you'll most certainly get more on 93 octane.
On a side note:
If you had intercoolers that would always cool the intake air down to ambient after the turbo, the temperature just before ignition would be the same regardless what boost pressure you start with or whether you even have boost at all. Temperature at that point only depends on initial temperature and compression ratio and is not pressure dependant. T2=T1*Compression_ratio^0.4 (according to the adiabatic compression law with air without adding anything that would evaporate and take a lot of heat such as water or fuel to a smaller extent). So more effective intercoolers can also help a lot to prevent pinging.
Of course once the air fuel mixture is ignited, pressure goes up higher the more air molecules you start with (which is boost pressure dependant) and with it does temperature and ping probability.
But, at least as far as I understand it: Tuning includes all factors that are adaptable and that does include boost pressure.
With optimal tuning I meant to optimize or max out all adaptable factors (fuel, boost pressure and ignition) in order to get maximum power.
The point is: If you say you'll get 400hp on 87 octance, you'll most certainly get more on 93 octane.
On a side note:
If you had intercoolers that would always cool the intake air down to ambient after the turbo, the temperature just before ignition would be the same regardless what boost pressure you start with or whether you even have boost at all. Temperature at that point only depends on initial temperature and compression ratio and is not pressure dependant. T2=T1*Compression_ratio^0.4 (according to the adiabatic compression law with air without adding anything that would evaporate and take a lot of heat such as water or fuel to a smaller extent). So more effective intercoolers can also help a lot to prevent pinging.
Of course once the air fuel mixture is ignited, pressure goes up higher the more air molecules you start with (which is boost pressure dependant) and with it does temperature and ping probability.
Last edited by globi; 04-01-2006 at 04:07 PM.
04-02-2006, 01:19 PM
#49
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i agree about the octane, but my point is saving $40/month at the gas pumps, while still having a powerful car. and if i don't hit 400, whoopity doo....370-380ish would be fine. if i were a power junky, i'd run race gas and crank that **** up to 25+psi
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