Oooooops

They go slightly better. All kinds of small changes.

You may want to look here

140bhp extra is no big deal to one of them. Thats 140 extra from 1000 revs up...

Them are the good ones.

Extra 40ish bhp over mine, so should notice the improvement

A predictable reply sir :) I think I'll concentrate on getting it on the road first!!

IMHO there's all sort of hype about them. As standard they've often got no more power than a good SP. Different if heavily modded for racing, of course, but if it was such an advance why didn't it become standard on later engines?

I couldn't comment but quite a few people who have driven both say there is a noticeable difference. I'm not really fussed though - the hype gives it a premium and therefore I hopefully got a prerry good deal

The problem is being certain that both versions are well and truly on song. Most are not. To try and meet the claimed fuel consumption they're set to run on the weak side. And production tolerances can turn this into not making the claimed power. I can certainly remember contemporary road impressions of the TP bearing this out - but unfortunately don't have any references to re-prints, etc. I also remember a family friend who was the manager of a main dealer who ran one as a company car and wished he could have had his old SP back. Despite having the BL rep involved, they never got it to be as perky as the old car.

Oh absolutely. It's the one everyone wants. I bid on TP bits to convert mine and they went way over my budget.

"I need TP for my bunghole"

More nitrous questions from me (but no I haven't got all the bits yet - told you I was a great procrastinator)...

- you say to run it 'a bit rich'. Won't the ECU just lower the fuel from the injectors to bring the mixture back into line?

- How much nitrous does it use on each burst? i.e. does using it for an overtaking burst a few times a day empty a 2kg cylinder in a day, a week or a month? Although if it works as expected a few times a day might be an underestimate ;-)

Cheers

Nope because once on WOT there is no feedback loop and its just a map. The oxygen sensor is ignored. And even if there is -- and it tries -- it doesent have enough adjustment to compensate. On nitrous we typically run 50 to 80 percent "rich" on road cars to prevent detonation and to keep heat and peak cylinder pressures lower.

Incidentally I updated that 8 year old site this week and added a forum.

I did that 5 years ago and couldnt keep up with the spam although it had a lot of interest then. Now less so because I require membership rather than guest posting.

You need a bigger bottle. 14lb is best although 10lb is neater.

You will use 1lb of gas for every 10bhp added per minute of use. Thats a long time though.

Not long enough is the general answer, it depends on how long the "burst" is and what size of jet you're using. Had a quick search and from figures people were giving I'd estimate a 2kg bottle (assuming 3.5lb of useable gas) would last about 45 seconds with a

50bhp jet and cost about 48p a second to use.

The way I've always checked for 'running rich' is to look at the exhaust colour after a run - but for short bursts that won't work. So, two things

- I'm going to use your suggested jet sizes (for +50bhp), that should be safe, no? - and is there a better way to test the richness of the mixture while at WOT?

I'll go and join up...

Maybe.. but that's an easy addition to the full system once I get used to it. It needs to fit invisibly as much as possible, and the bigger cylinders get much more difficult to hide.

so for my expected 50bhp, that's about a pound of gas for a 12 second burst. Ouch!

With unleaded fuel looking at tailpipes wont tell you a thing. It doesent colour the exhaust much if at all. Remember the days where a good thrash meant a grey tailpipe? Lead oxide. Now there isnt any...

It still colours "used" plugs though slightly.

You will also find that a WOT in say 2nd or 3rd will colour plugs on nitrous.

Without Nitrous -- Keep WOT until you hit max revs/redline whatever, and simultaneously press clutch, switch off ignition, and put in neutral. Dont let the engine turn. Slow/brake and stop. Pull all plugs and examine. Check OUTER ring for colour. Light tan is what you expect. Make sure the centre electrode is a normal colour and not burned white for eg.

Do the same trick on Nitrous.

Outer ring should be darker than before or show some black specs if looked at with a magnifying glass. These bits are the exess fuel that wasnt oxydised. That proves it is rich.

Its easier to just drive it on nitrous and "feel" if its rich. If it pulls and the pull fades away its rich. too rich. If it pulls and keeps pulling its ok. Then check plugs.

The static test will also tell you if you are in the safe/ rich ballpark. Details on site.

Yes ouch... Lasts longer than you expect though in reality. Because a) you accelerate hard so not for long b) you use about ten bottles in a week untill the novelty wears off and then only use it when some smug git in a posy car with his girlfriend pulls up next to you...*

• Works even better with a V8 in a 1.6L sleeper sierra with 140bhp extra... Leave in 2nd with smoke, hit third and leave.

Ah well, there you go you see. The last time I had to touch the mixture on a car was when it still worked... now I've always just let the ECU do it.

Sounds like an exciting trip out.. I'll have to do it when 'she' isn't in the car ;-)

...and if the pistons melt out of the side of the block it was way too lean?

Actually I'll be starting gentle and moving up the jets slowly so it shouldn't be too risky. It'll be stopping moving up the jets when I get to where I told the insurance I was going to stop will be the hard part.

Now *that* sounds like a good test.

Nah, I'm above all that ;-)

Hmm. Around 1p per horsepower per second for gas. Puts the cost in perspective... Good job I'm only doing it for the hell of it.

Then you start paying by the second for tyres as well!

Wideband lambda sensor.

OK...I'll rewphrase that. Is there a *sensibly priced* way to test it?

Does that sort of info come out to the OBD-II port if I get a better-than- basic reader? Or is that just fault codes?

Photos of the new kid on the block:

Seems to go pretty well, although it's desperate for some TLC. It's having a proper check done in the week, so hopefully the rust isn't too bad.

Mixture on the dyno is also easy.

3 RUNS. In this case a very stock 70 mile old not yet run in 136bhp suzuki bike. I have no mechanical sympathy. My DIY nitrous system, 50bhp jet in nitrous My home designed Dyno, what can go wrong? Blue curve - no nitrous. No extra fuel. Green curve = 50 bhp nitrous and too big fuel jet. It black smoked, and still made 180 bhp. Exhaust temp LOWER than stock, plugs very rich. Graph wavy... It should be the same shape as stock but bumped up by 50 bhp. But its safe like this and fast as F**k.

Red curve - 50bhp Nitrous jet, but smaller fuel jet. Graph almost the same shape as stock but a tiny bit wavy. That shows its still rich, exhaust temp higher than stock but not exessively so. 190bhp...

Its still a touch rich so safe. Shows no sign of detonation or other issues.

Before and after.

More importantly this is the torque curve.

Look at the step in torque! Thats actual acceleration that you feel! If it doesent wheelspin...

No amount of conventional tuning can do that.

Notice that this was at 7400 rpm. Imagine the size of the step at 3000 should you be brave enough to try it...

See the wavy "rich" 180bhp graph? With a sensitive bum you can feel that richness too. You want to be on the edge of feeling it and not, with specs of black on the plugs then you wont melt your motor!

! Wait...

Its worth it!

It still wont tell you what the correct mixture is though. Since there is no "correct". The more power you add the richer and more retarded you need to go so as to keep high average cylinder pressures with low peak cylinder pressures and temperatures.

That way a stock engine sees no more stress than it did before. At the expense of inefficient use of nitrous. But I can get 300bhp from a stock 1 litre bike engine without damage. Or similar on cars.

Its more important to know exhaust gas temp than mixture. Richer is cooler. Its also important to know peak cylinder pressures so as to be able to retard enough at any given power setting to prevent pressures that cause detonation. Actual mixture up to and including leaving a cloud of black smoke irrelivant if thats what works to get the power.

Wont help.