nitrous

[andybond]

Surely ( I know you are called Dave ) the turbos main job is to compress the gas going into the turbo by means of the amount of exhaust gasses coming out? To gain the force you need the gas to escape at maximum velocity and cleanly out of the exhaust side of the engine.

Faster / cleaner the gasses escape means a more efficient throughput of gas on the inlet side ?

If you smooth out the inlet side then you get "fuel puddle" , you want a bit of rough ( fnar fnar ) for fuel atomisation .. I am with Scoff on this one.

[Dave Reed]

Maybe in a n/a engine, but with nitrous you'll benefit much more opening up the exhaust side.

[kentraider]

Maybe in a n/a engine, but with nitrous you'll benefit much more opening up the exhaust side.

faster the gas leaves ...faster it can come in

[DaveL485]

faster the gas leaves ...faster it can come in

Not if the inlet system is restricting it.

[andybond]

Not if the inlet system is restricting it.

That must surely only be relevant in the top end ( in terms of power ) though ? The limit will be the velocity of the gasses leaving in turn speeding up the gasses being shoved back in ?

[andybond]

I love this place !!!

Just for the record Matt , whats your take on Nitrous ? All work on exhaust and none inlet ? Or bit of a tickle on both sides ?

[DaveL485]

There may be an advantage in a smaller inlet valve as the gas velocity across it will be higher and so convey more of the dense nitrous in less time.

Incorrect. Common assumption, but you're wrong.

The port gas speed doesn't alter (significantly) when an engine has forced induction. If the manifold pressure doubles then so does the gas density and therefore the mass flow and power. The speed stays the same.

[Matt@CodeRedMotorsports]

Me? Nitrous.....?
No No No!

[andybond]

Me? Nitrous.....?
No No No!

Maybe?

[Matt@CodeRedMotorsports]

Nah, sorry.
Never a big fan of the stuff.
LOL!

[andybond]

Nah, sorry.
Never a big fan of the stuff.
LOL!

Same !

Cheating gas not nitrous

[DaveL485]

Same !

Cheating gas not nitrous

If NoS is cheating, so are bigger injectors and a FMIC....at the end of the day they do the same thing....cool the charge and increase combustion materials

[Red October]

Ive got bigger valves in he head and a valvetrain to take the hammer.

[Dave Reed]

I wonder how many actually know where nitrous came from 😉

Without google lol

[The new Bill J]

I wonder how many actually know where nitrous came from 😉

The tank in the boot

[DaveL485]

I wonder how many actually know where nitrous came from 😉

Without google lol

Drag racing? (technology wise, I assume thats what you mean)

EDIT: I googled...I knew about the use in *that* but I didn't realise it was the origin of it!

[TopCat]

Nope..

I know it's laughing gas- used by dentists and GP's wasn't it?

[Dave Reed]

I know it's laughing gas- used by dentists and GP's wasn't it?

It is the same stuff yes (although much more pure, works even better too) but not where it came from in the use of a combustion engine.. (Which I should really of said in the first question).

[The new Bill J]

WW2 fighter planes used it.

[ScottKinnear]

I seen nitrous for the first time in quantum leap.

Wanted it ever since.

Also I read Dave's post and I didn't think it was obnoxious at all. Ian you went over board and should just apologies on this one. No way for an admin to act imo

[TNT ANDY]

Petrol is cheating - them darn horses don't stand a chance

FFS - if someone want's to have a go - help em out people. If chasing numbers is your game - go for it. FFS some people try to spend all day trying to get tiny white balls in 18 holes.

And then there's golf!

[Slammed 66]

Boring bits removed

[ScottKinnear]

If NoS is cheating, so are bigger injectors and a FMIC....at the end of the day they do the same thing....cool the charge and increase combustion materials

[Matt@CodeRedMotorsports]

I've always thought of nitrous used in a road car a bit too 'fast and furious'.

If it's used in top end 1/4mile drag runs to help push it over the line a millisecond quicker than the next guy, then I can only think of big block yank machinery.....

If someone wants to fit it to a wheezy 1.4 pushrod engined tin can (without sounding too nasty to the R5gtt) then let them go ahead, it's not my engine rebuild I'll be paying for/moaning about.......that's just my thoughts.
It seems like a sledgehammer/nut thing to me.

[TopCat]

I've always thought of nitrous used in a road car a bit too 'fast and furious'.

If it's used in top end 1/4mile drag runs to help push it over the line a millisecond quicker than the next guy, then I can only think of big block yank machinery.....

If someone wants to fit it to a wheezy 1.4 pushrod engined tin can (without sounding too nasty to the R5gtt) then let them go ahead, it's not my engine rebuild I'll be paying for/moaning about.......that's just my thoughts.
It seems like a sledgehammer/nut thing to me.

I'm with u on this one. Same as Efi on a c1j.

[Dave Reed]

Lol Matt.. A common misunderstanding with nitrous, why would u need to rebuild the engine? If the tune is good then it's fine to use. I only ever had one mishap and that was pushing the standard liners too much/possible tune.. That was an extra 100hp mind

Why you ask to out in on a 1.4 to go fast is the answer.. Also it's not used at top end only

[Dave Reed]

I'm with u on this one. Same as Efi on a c1j.

Ok if you like going slow with an oe car, poor setup for making it go quick

[TopCat]

Ok if you like going slow with an oe car, poor setup for making it go quick

Lol, I'd sooner spend the money on fitting a turbo charged 172 lump rather than spruce up the c1j.

[Dave Reed]

Lol, I'd sooner spend the money on fitting a turbo charged 172 lump rather than spruce up the c1j.

Lol fair point, but then the heart of the car is gone.. And believe me there's no reaction like telling people you've only got a 1.4

[TopCat]

Lol fair point, but then the heart of the car is gone.. And believe me there's no reaction like telling people you've only got a 1.4

Do you run Efi mate? Be good to see a set up in the flesh!

[Dave Reed]

Do you run Efi mate? Be good to see a set up in the flesh!

Used to.. Sold up over a year ago now

[Matt@CodeRedMotorsports]

Lol Matt.. A common misunderstanding with nitrous, why would u need to rebuild the engine? If the tune is good then it's fine to use. I only ever had one mishap and that was pushing the standard liners too much/possible tune.. That was an extra 100hp mind

Why you ask to out in on a 1.4 to go fast is the answer.. Also it's not used at top end only

I guess I meant its for when it goes terribly terribly wrong....

[DaveL485]

Lol, I'd sooner spend the money on fitting a turbo charged 172 lump rather than spruce up the c1j.

That's cheating (According to Andy Bond )

To quote scoff (I hope you don't mind mate), "If you can get enough gas in and out of the head you'll make as much power as you want". I agree, for sure.
What we are doing is triggering a series of explosions, one at a time, in a confined space. The bigger each explosion is, the more power we get. Easy to increase power then- more "explosive" (air and fuel mixture), right? Right....erm....yeah.

So, we change different criteria that will affect the amount of combustible material that ends up in the chamber. Thats it, as complex as it sounds sometimes, thats all tuning is. Very simple. Trouble is, the baseline you start with, be it a C1J, J7R, RB26 or YB will always be your limiting factor. Size, shape, component limits...take away those and power is easy. EASY. Remember old skool Turbo F1 cars? Est 1500hp in Quali trim from a 1.5L Turbo lump. Fifteen hundred horsepower from a capacity 103cc more than a C1J, because it's optimised without compromise for gas-in, BIG BANG, gas-out.

My point, I guess, is that Nitrous Oxide helps us get so much more combustible material in to that cylinder that the limitation we hit is component failure*, and because of that it gets a bad rep. It gives such a dense charge AND extra Oxygen to which we throw extra fuel as well, suddenly we aren't so much stuck with "normal" issues of flow, capacity, and suchlike.
For those that discount it, why? It just does what all the other tuning components do (or contribute to), just far better as a single, standalone modification.


*Discounting the dumbo's that set it up badly and grenade the engine because its running way out of whack

[Matt@CodeRedMotorsports]

Just make sure if you do go down the nitrous route, pray your engine is in a good state, you sure don't want a 'nitrous backfire'.....

[DaveL485]

Lol fair point, but then the heart of the car is gone.

This is my hangup too, otherwise i'd throw an Evo lump in the 21, buy off-the-shelf bits for an easy 600bhp and laugh all the way home.

BUT.

When you open the hood, people would say "aaaaaaahhh it's an Evo lump" like, I don't know, like it explains why the battered old R21 is actually fast. Tsk...as if the original engine could be quick....pah! Preposterous!

No....I want to open the bonnet and see eyes widen to the sight of the J-series engine. I want to see the disbelief, I want to see the expectation of the transplant drop off everyones faces. And I want to stay as true as I can to the car itself, and thus I have to stay within those limitations that come with it as mentioned above.

[DaveL485]

Just make sure if you do go down the nitrous route, pray your engine is in a good state, you sure don't want a 'nitrous backfire'.....

I'll tell you the spec of mine, if you're interested (it's not a C1J though it's a 1995cc, SOHC J7R from the 21 Turbo)

[Matt@CodeRedMotorsports]

Is it the spec in your profile?

[Ricardo]

Used to.. Sold up over a year ago now

Absolute weapon of a 5

[kentraider]

Absolute weapon of a 5

too bloody rite... ridiculous 60 foot times...thats the nos for ya lol

[DaveL485]

Is it the spec in your profile?

Nope, thats old and what was on the car when I registered. Since then it's had new fuelling and Adaptronic fitted, and then the spec i'm talking about above is a total new build altogether.

[Scoff]

Hmmm. Interesting. I sit in the other camp with regards to valves....surely the inlet is the biggest benefit by far? Getting the exhaust gas out is nowhere near as hard as getting the inlet gas in, for starters exhaust ports flow in the opposite direction to inlets... a large part of what determines the flow efficiency of inlet ports themselves is how well the port guides the air to fully utilise the entire circumference of the valve seat. In nearly all cases this can't be achieved because air travelling at high speed can't get round the short side bend in the port and just skips across the back of the valve head and tries to exit through the long side of the valve seat.
The exhaust port doesn’t fall foul of this…. The air already uses the full circumference of the valve seat by virtue of the fact it's going into the seat from all round the combustion chamber anyway. Provided the port itself is big enough then almost any design of exhaust port will flow at a good efficiency because the valve (seat) is being used effectively. Even the shape of the short side bend is not that critical because it's not having to guide the gas IN to a seat - all it's doing is guiding the gas into the port.

TL : DR- Exhaust valves work better, naturally. Hence inlet improvements being something I would prefer to focus on.

I would be very much interested to hear any rebuttle on the above, seeing as, y'know, I chucked three and a half thousand quid at a cylinder head that you're going to tune for me based on my "inlets are best" theory

The rules change when you're putting in 100hp or more of nitrous Dave. The denser charge from cooling helps to relieve the need for a bigger inlet. And you're not trying to put more gas through them, so why bother. Infact you want to keep gas speed up, so there is no point in making them larger than necessary. More importantly you have a lot more exhaust gas than you did before you switched the nitrous on.

The C1J's exhaust ports are very poor so there is gain to be had there with nitrous. The same might not be true of other engines.

With nitrous you can use a bigger turbine, and you should. Anything that helps the path of exhaust gas in a nitrous engine is a bonus.

[Bigfoot]

Had a read of this website which I thought was quite interesting on what is needed to do to the head when running NOS

http://www.akamoto.co.uk/info/Nitrous-head-mods.htm

[Scoff]

Boring bits removed

Thankyou! It makes reading the forums so much nicer when there is no crap to wade through

(I should add: I don't know what was deleted, and by who they were posted, but I think it's nice to have tech topics without any BS.)

[andybond]

The C1J's exhaust ports are very poor so there is gain to be had there with nitrous.

How so ? restrictive size ?

[Scoff]

How so ? restrictive size ?

Size, design and irregular casting Andy.

[andybond]

Size, design and irregular casting Andy.

Understand the size thing ( ie too narrow ) , talk to me about design : I guess it is the tight curve on 1 and 4 and the staight exits interrupting on port 2 and 3 ?

Irregular casting ? The rough and smooth and irregular diameters ?

[Scoff]

By irregular casting Andy I ment the differences in port shape you picked up on already

[andybond]

By irregular casting Andy I ment the differences in port shape you picked up on already

Cheers. Appreciate the insight.

[DaveL485]

The rules change when you're putting in 100hp or more of nitrous Dave.

Ah- understood now. NoS = Different rules

My exhaust valve is a beast, 40.1mm diameter with a port to match, and to be fair I don't think I could get any bigger if I wanted to anyway....the fecking bespoke exhaust valves were £84 plus VAT....EACH so stuff doing that again.

Inlet-


Exhaust-


Valves-


'tis a work of art that head (probably only IMO though )

Question: On this head the 'plug comes in from the exhaust side. On the 8v, the plug comes in from the inlet side. I don't know whether to use a hotter rated plug or not, after all, the electrode ends up inside the big fiery chamber whatever happens. Thoughts?

[andybond]

Ah- understood now. NoS = Different rules

you twerp. Look at the title of the thread.