93 octane in a 2007 Honda Civic

[exar333]

WRX Invoice starts at $24,079
Si Invoice starts at $22,405 ???? ~$1,600? I know there are more options you can put on the WRX vs. the Si, but it's not an epic difference. Are you sure you're not thinking of the STI? Because that sucker is pretty darned expensive indeed, much like the Evo.

Or are prices just retarded in Canada, lol?

Both use premium gas and are pretty close in price. I wonder which engine I would want? ~200hp w/ crappy torque, or 260hp with about 100ft/lb more than the Si...

Tough choice....

 

[Arkaign]

Both use premium gas and are pretty close in price. I wonder which engine I would want? ~200hp w/ crappy torque, or 260hp with about 100ft/lb more than the Si...

Tough choice....

lol yeah with pricing that close it's a tough call to go Honda. The subies seem to be really reliable, are pretty easily moddable (always easier to add boost to stock setup than try to go all-motor or add FI to a NA setup), and the AWD means that it can put power to the ground quite a bit easier than FF when you start getting the power up there. Getting a Si up to really high FWHP levels would be pricey though. I guess the cheapest way would be nitro, but imho high stock compression + nitrous = bad?

The shifter in the Si is really nice though

 

[vshah]

in late '07 when I got my Si, i thought it was the nicest combination of daily driver and some fun thrown in the mix on the market at the time. These days the competition in the <$25k segment has improved considerably...I'm not sure I'd make the same choice again. I still love my Si to death though. I get to drive it tomorrow after 2 weeks...so excited.

 

[Arkaign]

in late '07 when I got my Si, i thought it was the nicest combination of daily driver and some fun thrown in the mix on the market at the time. These days the competition in the <$25k segment has improved considerably. I still love my Si to death though. I get to drive it tomorrow after 2 weeks...so excited.

Yeah, indeed it's still quite a nice ride, particularly when compared to regular econoboxes. And they hold their value extreeeeemely well, something to be said about that for sure.

 

[jhu]

It will effectively remove some of that annoying excess money you've got.

Go for it!

Won't someone please think of the oil companies???

 

[Vic Vega]

I've been running 87 in my Ford 4.6L 2V V8 for 160,000 miles. No problems so far.

 

[exar333]

in late '07 when I got my Si, i thought it was the nicest combination of daily driver and some fun thrown in the mix on the market at the time. These days the competition in the <$25k segment has improved considerably...I'm not sure I'd make the same choice again. I still love my Si to death though. I get to drive it tomorrow after 2 weeks...so excited.

Thats for sure. There is the MS3, GTI, and WRX all at or below that 25k mark and they have all increased the power you can get for the $$$, plus they are al FI and can be modded pretty easily. Honda really just stood still and thinks 200hp/150tq is enough for a 'performance sedan' now. Its not.

Nice car anyways, but why get a new one when yours is just as good.

 

[yottabit]

I guess the cheapest way would be nitro, but imho high stock compression + nitrous = bad?

Actually the opposite is true, you want fairly low compression ratio for a forced induction application but high compression ratio for N/A and Nitrous. Technically I think you could get away with even higher compression ratios with nitrous due to the cooling effect it has.

It also has a compound effect on forced induction cars that boosts horsepower more dramatically. That's why you see a lot of big turbo setups running 50 shots, 75 shots, it helps spool up and also cools the charge substantially.

 

[yottabit]

in late '07 when I got my Si, i thought it was the nicest combination of daily driver and some fun thrown in the mix on the market at the time. These days the competition in the <$25k segment has improved considerably...I'm not sure I'd make the same choice again. I still love my Si to death though. I get to drive it tomorrow after 2 weeks...so excited.

That's a very good summary.. I think it used to be the class killer car but now there are a lot of other options. I don't think it makes the car any less great though

 

[Arkaign]

Actually the opposite is true, you want fairly low compression ratio for a forced induction application but high compression ratio for N/A and Nitrous. Technically I think you could get away with even higher compression ratios with nitrous due to the cooling effect it has.

It also has a compound effect on forced induction cars that boosts horsepower more dramatically. That's why you see a lot of big turbo setups running 50 shots, 75 shots, it helps spool up and also cools the charge substantially.

Interesting, I'd heard that it's dangerous, but have never used it personally.

 

[hanoverphist]

I've been running 87 in my Ford 4.6L 2V V8 for 160,000 miles. No problems so far.

my friend has that engine in his truck too. when he was repairing my front end on my dodge, he let me drive his truck while mine was in the shop in pieces. 4 weeks of me putting 87 in it and he could tell the difference when he got his truck back.

 

[dud]

Wife has a 2007 Civic. Question was ... worth using it?

Hell no!


... unless you like wasting your money.

 

[yottabit]

Interesting, I'd heard that it's dangerous, but have never used it personally.

The perception that nitrous is dangerous is mostly due to improper installations and predominantly people trying to use dry kits with very little tuning. Nitrous can actually be a really safe way to add power and very straightforward with a wet shot.

Dry shot kits = nitrous only, extra fuel needs to be supplied by car's existing fuel system (needs tuning)
Wet shot = nitrous + extra fuel goes in, requires little tuning and is pretty fool proof

You can run into issues if you engage nitrous at too low of an RPM or partial throttle, which is why a good setup would have a window switch for RPM as well as a microswitch or other trigger switch on the throttle. Most of the people who blow up their engines are idiots who installed a dry kit and tried to run it without tuning (I know some) or improperly sized the jets for their wet kit.

Most cars will take a 50-75 (hp) wet shot and not have any serious problems. You're usually limited by the connecting rods The nice thing about nitrous systems is (for the most part) you can carry a lot of the parts over from car to car if you change vehicles, unlike other poweradders which are pretty much customized to that vehicle

 

[Zenmervolt]

Actually the opposite is true, you want fairly low compression ratio for a forced induction application

Not really.

What you're really worried about here is cylinder pressure. If you're running 14.7 PSI of positive manifold pressure in a forced induction setup and have an 8:1 static compression ratio, you're still compressing the charge as though the compression ratio were much higher (nearly double). (14.7 PSI is one atmosphere, so 14.7 PSI of positive manifold pressure is 2:1 compression of the intake charge before it hits the cylinders.)

If you can control detonation at those higher cylinder pressures and the components can withstand it, then you'll still get more performance out of a forced induction setup with higher static compression ratios. You can see this trend as turbos have been improved over the years. My '86 944 Turbo has an 8:1 static compression ratio, but the newest 911 Turbos have 9.8:1 static compression ratios, which is the same as the compression ratio for the early '80s non-turbo 911 models. As combustion chamber design improves, manufacturers have been able to increase the static compression ratio on all engines.

Ideally, with both NA and forced induction setups you want high static compression ratios. It's just that cylinder pressure becomes a practical limiting factor which forces lower static compression ratios in forced induction engines.

ZV

 

[IcePickFreak]

It's a Civic, you need

It's like a 100 shot in your tank!

 

[yottabit]

Not really.

What you're really worried about here is cylinder pressure. If you're running 14.7 PSI of positive manifold pressure in a forced induction setup and have an 8:1 static compression ratio, you're still compressing the charge as though the compression ratio were much higher (nearly double). (14.7 PSI is one atmosphere, so 14.7 PSI of positive manifold pressure is 2:1 compression of the intake charge before it hits the cylinders.)

If you can control detonation at those higher cylinder pressures and the components can withstand it, then you'll still get more performance out of a forced induction setup with higher static compression ratios. You can see this trend as turbos have been improved over the years. My '86 944 Turbo has an 8:1 static compression ratio, but the newest 911 Turbos have 9.8:1 static compression ratios, which is the same as the compression ratio for the early '80s non-turbo 911 models. As combustion chamber design improves, manufacturers have been able to increase the static compression ratio on all engines.

Ideally, with both NA and forced induction setups you want high static compression ratios. It's just that cylinder pressure becomes a practical limiting factor which forces lower static compression ratios in forced induction engines.

ZV

I think my point of "fairly low compression" is still valid- you're right that the turbo cars of today have compression ratios that match the NA cars of 20 years ago, but in the same time the compression ratios of the NA cars today have gone even higher.

For the same amount of boost a higher compression ratio WILL produce more power, however IMO for absolute maximum power on a turbo charged engine you will inevitably end up with a low compression ratio. There are many advantages to high compression ratio boosted engines- mainly faster turbo spool, better off-boost response, and better cruising efficiency. But if drag racing or max power output is your goal I know dropping the compression ratio and cranking up the boost is the way to go.

I would love to know why this is because I'm certain there is less chance of detonation at a given power level with low comp/high boost rather than high comp/low boost... but I'm not sure why.

 

[LTC8K6]

It's a Civic, you need

It's like a 100 shot in your tank!

3 points is .3 right?

From 87 to 87.3

 

[JCH13]

I would love to know why this is because I'm certain there is less chance of detonation at a given power level with low comp/high boost rather than high comp/low boost... but I'm not sure why.

Assuming the both engines compress the intake air the same amount, i.e. the higher boost exactly cancels out the lowered compression. I think the high boost/low compression setup has a lower chance of detonation because more heat was removed from the intake charge via intercooler. The air coming from the turbo's (or supercharger's) compressor side is hotter because it's being compressed more. Hotter air will reject more heat in the intercooler (assuming it's not saturated) which means there will be less heat and lower temperatures in the cylinder as the intake charge is compressed, resulting in a higher detonation threshold.

This is just a hypothesis, but I think it makes sense.

 

[Zenmervolt]

I think my point of "fairly low compression" is still valid- you're right that the turbo cars of today have compression ratios that match the NA cars of 20 years ago, but in the same time the compression ratios of the NA cars today have gone even higher.

For the same amount of boost a higher compression ratio WILL produce more power, however IMO for absolute maximum power on a turbo charged engine you will inevitably end up with a low compression ratio. There are many advantages to high compression ratio boosted engines- mainly faster turbo spool, better off-boost response, and better cruising efficiency. But if drag racing or max power output is your goal I know dropping the compression ratio and cranking up the boost is the way to go.

I would love to know why this is because I'm certain there is less chance of detonation at a given power level with low comp/high boost rather than high comp/low boost... but I'm not sure why.

The reason is that with a lower compression ratio you can have more boost without having to resort to much more expensive things like computer-assisted combustion chamber design. It's a cost and practicality concern. If you could make an engine out of unobtanium then you'd go with high-compression and forced induction, but that doesn't work in practice because there are limits to the cylinder pressures that can be managed cost-effectively.

ZV

 

[exdeath]

My '86 944 Turbo has an 8:1 static compression ratio, but the newest 911 Turbos have 9.8:1 static compression ratios, which is the same as the compression ratio for the early '80s non-turbo 911 models. As combustion chamber design improves, manufacturers have been able to increase the static compression ratio on all engines.

Ideally, with both NA and forced induction setups you want high static compression ratios. It's just that cylinder pressure becomes a practical limiting factor which forces lower static compression ratios in forced induction engines.

ZV

On a related note:

Then there is the concern for mod potential. Given two stock turbo cars within the same period (similar head and combustion chamber designs), the one with the lower static compression ratio will allow you a greater ceiling for increasing the boost way beyond the factory setting. The higher compression ratio of the other may initially be more powerful in stock form on paper, but the higher CR will become the limiting factor when we start talking about swapping turbos and modding to 20 and 30 psi.

At that point it depends entirely on what you are looking for. You'll get a flatter curve and better throttle response on the high compression low boost engine but be limited on the maximum boost and power output. Some people are ok with that and don't need to go to the moon and back. The car with the lower compression engine able to run more boost is likely to be the faster car when all is said and done. Primarily for the reason that compressing air with a turbine is far more effective than with a piston.

 

[VinylxScratches]

My car takes low grade but when I put mid grade in there it drives a little better.

 

[Doppel]

It's a Civic, you need

It's like a 100 shot in your tank!

Just be careful with the welds on that intake.