to NOS or not to NOS

[944Newboy]

Hi Guys, this may be bordering on something the Essex brigade do with old fords, but what about adding a NOS kit from the wizards of nos. Should a 23 year old 944 Engine be subjected to such treatment late in life. Will the internals take it? How much extra bhp should I go for 20, 50 hardly worth the effort what about 150? Any one done this already, how long did the engine last?

[Merritt]

If you read the info on their site, you'll notice that torque is one of the biggest improvements.. Power is just a by product. Nitrous oxide increases the BMEP (Brake Mean Effective Pressure) and has the opposite effect of turbocharging in terms of intake temps (turbos make intake charge hotter, whereas Nitrous cools it which is why bigger gains are to be had with turbod cars).

I believe they only allow you to start with small jets anyway so that you get the mix right before whacking large amounts of nitrous in to the equation.

I suspect you will be fine with small amounts but remember if there are any weak links in the chain i.e. clutch / transmission / piston rings etc then nitrous will assist in making the problem worse.

The other problem you may have is insurance... I looked in to this a long time ago with an Elise and insurance is a VERY grey area. BTW I didn't do it in the end because the K series engine is made from chocolate.

Steve

[magic torch]

Do it.

If I had the spare space, mine would be on the laughing gas.

[fidgits]

I'm not a fan of NO2. (NOS is actually a company)

If your after an occasional blast of extra power, its okay - but re-filling gets very expensive very quickly if you use it with any regularity, and IMHO your better off looking for a turbo/Charger conversion.

I had a friend who got a kit from the people you mention fitted to a GS300 - it was used an awful lot, and the engine did let go on a track test.

At the end of the day, you pays your money, you takes your chances - I wouldnt touch NO2 personally, but then thats me.

[arwebs]

Merritt said:

turbos make intake charge hotter, whereas Nitrous cools it which is why bigger gains are to be had with turbod cars

Are you sure? I was always under the impression that higher efficiency and hence higher outputs were produced with cold air. The intake air in a turbo is generally cooled by intercoolers for this very reason, n'est pas?

[fidgits]

arwebs said:

Merritt said:

turbos make intake charge hotter, whereas Nitrous cools it which is why bigger gains are to be had with turbod cars

Are you sure? I was always under the impression that higher efficiency and hence higher outputs were produced with cold air. The intake air in a turbo is generally cooled by intercoolers for this very reason, n'est pas?

Actually... dont get confused here, there are two principals involved with O2 and more power.

In a nutshell - the more O2 you have, the bigger 'bang' = more power (vastly simplied, but you get the point)

The way a turbo works is that it uses a turbine to compress the air before feeding it into the engine (same as a supercharger, the primary difference being how they are driven, turbo via exhaust gases, a charger via a belt from the engine).

Compressed air has more O2 per square inch, thereby has a bigger bang.

But Merritt is correct - the method of compression increases temprature - which brings us onto the other factor.


Temperature effects O2 density - basically, in colder air you have more O2 per square inch (same principal as before) - so this effect can make turbos less efficient - which is why they introduce intercoolers - to try and cool the air first to counteract the effect.


However, NO2 is the method of introducing NO2 instead of (well, as well as, but replacing some of) air into the cylinder, as NO2 creates a bigger bang.

[magic torch]

Providing your not after massive power gains it shouldn't affect the engine life. Some people argue the reverse is true.

[fidgits]

magic torch said:

Providing your not after massive power gains it shouldn't affect the engine life. Some people argue the reverse is true.

erm.

I think its actually subjective, on the following factors:

1. The current condition of the engine (any increase in power is likely to accelerate the wear rate, and make any faults on the horizon to happen sooner)
2. The amount of power your after - I think 75 or 100 jets would be your maximum limit (so up to about 50bhp)
3. The amount you use it.
4. How hard you push the engine while using it.

[magic torch]

fidgits said:

magic torch said:

Providing your not after massive power gains it shouldn't affect the engine life. Some people argue the reverse is true.

erm.

I think its actually subjective, on the following factors:

1. The current condition of the engine (any increase in power is likely to accelerate the wear rate, and make any faults on the horizon to happen sooner)
2. The amount of power your after - I think 75 or 100 jets would be your maximum limit (so up to about 50bhp)
3. The amount you use it.
4. How hard you push the engine while using it.

Yep, appreciate you know your stuff.

There's a lot of myths surrounding it, my understanding was a cooler burn with small jets wouldn't have any adverse affect on engine wear.

[fidgits]

Thats I fair point, after all the big benifit of NO2 is the lower ignition temperature.

As you said, there are two schools of thought, one of the counter arguments is based along a much steeper pressure curve within the cylinders, but I don't fully understand the argument to know whether it is correct.


As has been said, most reputable companies will start you on 25bhp jets (about 10bhp increase) and gradually step up to avoid any major engine damage.

Jamie is right, if you stick to the smaller jets, and dont overuse it - you shouldn't suffer any problems apart from those that would have happened anyway.

[944Newboy]

Thanks guys. Now even more unsure, would it be worth fitting to get 20-40 bhp in bursts. I was thinking more like 100bhp for 5 seconds to pass that Evo or Scooby do on the exit of a bend or just surprise the life out of them away from the lights. Have asked the experts at Northway about the possibility of sticking a Turbo in when I melt this one.

[magic torch]

From what I've seen it doesn't come in like something out of the 'Fast and Furious'. It's an increase across the rev-range, not a sudden hit.

Personally I wouldn't risk 100bhp.

[fidgits]

magic torch said:

From what I've seen it doesn't come in like something out of the 'Fast and Furious'. It's an increase across the rev-range, not a sudden hit.

Personally I wouldn't risk 100bhp.

Nail. Hit. Head.

[944Newboy]

fidgits said:

magic torch said:

From what I've seen it doesn't come in like something out of the 'Fast and Furious'. It's an increase across the rev-range, not a sudden hit.

Personally I wouldn't risk 100bhp.

Nail. Hit. Head.

Wallet and wasted cash then LOL

[wildoliver]

944Newboy said:

Have asked the experts at Northway about the possibility of sticking a Turbo in when I melt this one.

Scary comment...........

[magic torch]

fidgits said:

magic torch said:

From what I've seen it doesn't come in like something out of the 'Fast and Furious'. It's an increase across the rev-range, not a sudden hit.

Personally I wouldn't risk 100bhp.

Nail. Hit. Head.

You know more than me!

Don't forget it's not just say 20bhp on the top end, it's an increase all over the rev range. As this graph shows (obviously a much wilder tuned car).

[fidgits]

944Newboy said:

fidgits said:

magic torch said:

From what I've seen it doesn't come in like something out of the 'Fast and Furious'. It's an increase across the rev-range, not a sudden hit.

Personally I wouldn't risk 100bhp.

Nail. Hit. Head.

Wallet and wasted cash then LOL

Not nesacerrily (eek - the spelling police will be here any second!!!)

You just need to understand it just makes your engine develop more power - not provide jet-like thrusts as the Fast & rediculous movies suggested.

The best analogy I can think of is:

Drive a 2.7 boxster down a straight road - put your foot down...
Then do the same in a 3.2S Boxster - thats the difference 50 to 75bhp jets will give you if you use the Nos.

In other words the car will behave exactly the same, but with just a bit more power, accelerate a bit faster.