You made a good point their Sam, about the air-cooled heads being an issue. Now I’m no expert and maybe someone can help me understand this a little more clearly. Lets take my 60hp Nos system and compare it to some one with a 60hp Turbo. Now our engines are really just heat engines in that they convert chemical energy too thermal energy too mechanical energy. So of coarse more mechanical energy (hp) will be directly proportional to more thermal energy. So you would think both system would cause the same amount of engine stress?

But the Turbo is excepted with open arm, where as the Nos is shunned…

Very similar. If you have the right A/F ratios with nitrous and a turbo, the nitrous will actually run a bit cooler given the same horsepower increase due to the expanding gas.

If you go with too much boost with a turbo bad things will happen. Same with nitrous oxide.

But most people who install a turbo creep up on the boost and don't get crazy, unless they have more money than I do.
With NOS it would be very easy to bolt on a bunch and then say, "let's try it and see what happens". With self control both systems will work. It is very easy to bolt on too much. With either system you have to be more careful with an air cooled engine.

I feel the turbo on my engine is part of the engine, a mechanical device that is designed to work in conjuction with the rest of the parts. No different than the cams or pistons. A turbo doesn't run out when the bottle goes empty.

IMO NOS is artificial and temporary. It doesn't make the engine more powerful, it tricks the engine into making more power. If that's what you want, fine. Use it. I just hate it when I watch these so-called "tuners" on TV pretending they are tuning the engine for more power when all they are doing is "cheating" by bolting on a NOS kit. Tuners my ass.
Sounds like I'm just too old ;)

Well after reading this post I am compelled to give my .02

I think for me James Garner put it best in an interview during a commercial break of the movie Grand Prix.
He did much of his own driving for this movie. When asked, what was it like to drive a car at close to 200 mph. he answered, going fast in a straight line isn't the thrill.
The thrill is going into a max 30 mph turn going 29.9 and hitting it just right

A couple of thoughts to ponder.
To be the fastest in a straight line, you need the biggest wallet.
To be the fastest on the track (road coarse) you need the biggest cahones.

the late great Peter Gregg sums up my feelings about drag racing perfectly: "It's been my experience that straight-line acceleration is probably the first aspect of automotive performance that any intelligent driver gets bored with."

Okay okay, but wouldn’t you guys like to get the next corner just a little bit quicker???

:D

wow,thanks for all the feedback...l guess we`ve established that NOS is not for the Porsche crowd and drag racers get no respect,road racers obviously being better,smarter,more skilled and generally more evolved human beings then the mullet wearing 1/4 milers.l`m a total gearhead so l do it all from motorcycle trials to circle track,1/4 mile/ autocross/TSD and vintage rally,you name it l think it`s all good!l`ve not yet become bored with skydiving and some might liken that to drag racing.To get back to the topic and away from the "my form of racing is better" l was wondering about NOS on an aircooled engine.l`d like to experiment,being the gearhead that l am and having already done the turbo route several times(not yet on a Porsche).My next post was going to be about electric superchargers but l think l`ll hold off for a while...

Don't let these guys get you down, raceman. If you want nitrous, then put the friggin nitrous on your Porsche. Sounds like a blast to me. :D

hey thanks Richard,l just may do that.The car l had in mind for it has been sold and l never was able to do the V8 conversion on it anyways.As for engine swaps in 911`s l`m always interested in seeing top notch wrench work but l`ve decided l`ll never do one..but the NOS? l`ll be sure to post pics if l go through with it,and show anyone who`s interested my clear tailights ....hehehe

Right!
Install it, run it, and tell us how it worked (or post the pictures of the "aftermath".

yeah Doug,it`s the "aftermath" l`m worried about. lt`s not like l`m spending a couple of hours installing a kit on a rental car with the full insurance.

hey raceman about those electric superchargers!! a friend of mine who owns a shop in pasadena was looking into them for a friends honda crx with a jdm acura rsx engine in it. he talked to the company for a while and there are some definate benefits to the system. the drawbacks i think outweigh the benefits at this time because the systems have not been used very much. on some applications you have to change your alternator and rewire a good amount of the car's electronics, add to that a very large and heavy electric motor you have your choices. the electric motor is capable of spinning the super faster than your engine can because it is not being limited by revs and we all know electric motors can spin up to insane rpm's. as far as using nos on a porsche i think a neat setup would be to use it as a fogging device in which at higher rpms where detonation is more likely to occur the computer tells the nos system to fog the intake tract therefore lowering temps a little bit. im not saying blow the whole bottle in merely use it as a device to add a little power but also to make the engine run safer. i have had luck in the past with using water foggers spraying over the intercoolers to gain some more hp and lower the temp of the charged air.

i do have to agree that the coolness of a nos system runs out when the bottle goes empty. why not use a boost surge button much like porsche did on the 956/962 when you want some extra go power.

that`s what l`m thinking too.Being a stunt driver and an incurable technogearhead l just want the Go button there,just in case.lt`s like that hundred dollar bill tucked up in the secret compartment of your wallet,you know it`s there,you know you can spend it but you wait.When the time comes and you pull the bill,that`s hero time,ka ching! think internal engine shots via Fast/Furious.l`ll be sure to post pics,people need to see the enemy right?

OK raceman back to topic. As I stated earlier I believe a 911 will handle a small shot of nitrous without any real trouble, the bottom end of these engines is certainly durable enough, it's just the heat capacity of the heads that I worry about. It's generally accepted that 911 heads run hotter than water cooled heads and when it comes to water cooled heads a good rule of thumb is that an aluminum head will allow about a half point higher compression than it's cast iron counterpart. Aluminum water cooled heads also allow for a larger nitrous shot. Now since air cooled heads are going to be worse than cast iron water cooled heads at disipating heat you'll be limited to less nitrous. Twin plugging will help as will a top notch ignition system and a dedicated secondary fuel system with all the safetys installed. It seems Frostie has the setup you're looking for and while he might be able to safely go higher I'd bet that 90HP is about the limit anything more and you'll need to seriously rework the engine with thicker pistons, special cams and possibly overdriving the fan for better cooling. On that note I suppose you could rig up a water spray system to kick in when on nitrous to help cool the heads better but you'd need a head temp gauge to check the safe zone. I would also highly recommend a wet fogger system like Frostie has and totally stay away from dry systems since they seem to cause a higher rate of engine failure in my experience.

As for me I'd only put nitrous on a 911 to augment a turbo or supercharger acting as a temporary liquid intercooler for those times when I feel it's necessary to spank some ricer butt! :)

thanks Christian,those damn ricers are pushing us to compete on their fields.l saw two 996`s parked at Pep Boys the other day and l think the owners were shopping for neon!One of the cars had the visor TV screens too.l have to say though that my Mitsubishi Galant VR4 could absolutely spank my 911.All wheel drive,boosted to 20psi with supporting mods there wasn`t much that would stay with me on the 1/8 mile.l sold it because of that-my Porsche felt slow after a while

If your serious about adding Nos to a Turbo/Supercharger engine it would work but it would be a complicated system. I think the biggest issue would be the density of the mixture going into the engine. To help with this sky-high octane fuel would work. I’ve read some threads about using propane as a fuel to mix with the nos because of it’s 104-120 octane, I believe I read somewhere that propane has a slightly lower burn rate but this maybe cured by the Nos. The propane bottle could be flip up side down so liquid shoots from the jets instead of gas this would also help very much with chilling the inlet charge. Pressure would remain pretty much constant until the bottle is almost empty. If the bottle runs empty your engine would melt in seconds. I defiantly need to learn more about this though.

So the nos logic would looks something like this.
If you’re at full throttle (limit switch)
If you’re RPM is between 3-6k RPM (rpm chip, rev limiter must be set higher then the RPM chip)
If fuel pressure is satisfactory (limit switch for gas @ 5psig, Propane?)
If you’re your intake manifold pressure is below a pre-determined pressure, say 4psig (this is where the turbo lag is taking place, you need the nos to cut out before too much boost or detonation)
If the nitrous activation switch is activated

Only if all the above are okay should your Nos kick in

Just my 0.02

A mechanic buddy of mine showed me a 3.0L piston a few years back with a nice hole burned in it after an over-dose of nitrous.
The only way I would do this with an expensive to repair 911 engine would be using all the safety switches and a dedicated fuel system of AvGas or toluene. 100hp max.
I view nitrous as a toy, be it a very powerful toy, with the ability to destroy if not respected. You might consider using a shifter mounted button to activate along with the other safety switches. I can't imagine what would happen to a 915 shifted under gas.

Back in the 1980's we built an all steel street VW bug that ran 14.40 @ 89 mph. With an NOS fogger set up it ran 11.70 @ 107 mph. On street tires! It looked super ugly and won a lot of $$.

FWIW Avgas is designed to atomize at high altitude in airplanes. Not good for automobiles. Stick with a good fuel like ERC 110.


http://home.earthlink.net/~hennad/fuller1.jpg

14.4 too 11.7, wow. :cool:

Don't think you don't need a big wallet to be fastest on a Road Course either. Talent driving your own car is only gonna get you so far.
Also when I went a 160 MPH on my ZX-11, I didn't even have a wallet. But I had cahones.

There ya go! Unless you're auto-xing, even road courses have straightaways where you may be running a rolling 1/4 mile every few minutes. Buttonwillow has a stretch of pavement called, you guessed it, "the drag strip" where only straightline acceleration is required. So the high and mighty can condemn drag racing as childish or lame, but it exists at many racetracks in one form or another. It just lacks the "tree" and the "trap".

I'm not a proponent of NOS, but dragracing in a safe environment has always been very enjoyable to me.