A/F Ratio type question

[Tintin]

I\'ve been mulling over a few ideas recently regarding charge temps and I wanted to check if lowering the intake will result in changing the A/F ratio

I\'m pretty sure it dosn\'t \'cause I seem to remember that if you get the charge temps down the air is denser which means you can fit in more fuel but as your actually getting more air in aswell the ratio should stay the same , is this correct


I\'m planning fitting WI in the future and am also planning on building a CO2 intercooler spray system , this should get the charge really cold . If all this did happen to lean it out a bit it should be fine as its running well rich at the mo


Another couple of ideas I had where would a CO2 spary work on the radiator to lower engine temps , this probably wouldn\'t be a practical use as you would need it on all the time to make any real use . The other was regarding charge coolers , I\'m hoping to go down the route eventually and was wondering if a CO2 spray on the CC radiator would have the same effect as spraying an intercooler


The reason I\'m interested in CO2 systems is I reckon I can build one really cheap , all depends on the price of the solonoid really as I\'m sure that will be the hardest part to source

Any of your vast wisdom will be great


Cheers

Paul

[NixRX7]

Will depend a lot on what pressures you want to run the CO2 at, straight from the bottle you are gonna be looking at between 400 - 1000 psi (depends what heat the CO2 is at)
if you are drawing off liquid, this will cause the bottle to freeze down lowering bottle pressure/ ambient heat will cause the pressure to rise.
Your best bet would be to have a regulater on the bottle, and use a syphon type bottle that draws off liquid, then just set your required pressure, i would imagine about 50 - 100 psi would do it.
Would not cost the earth to get a solenoid that runs at this pressure, just so long as its designed for use in cold applications.
If you get a pressure controlled solenoid that triggers at say 5 - 7 psi you could have it rigged so that as soon as you start to boost it opens the solenoid and gives a nice cold blast to the intercooler/intake pipes etc.

You can actually buy ready made systems that do all this, but they are pricey, as you say it would not cost a great deal to make one yourself.

I have made up a lot of systems like this, but never for an automotive application.

[Tintin]

Cheers for the input ,

All the info I\'ve got on this subject is designed for making NO2 systems and it states not to use regulators as it causes the liquid to boil and foam , I suppose it is very important to properly meter the amout of NO2 being injected into the intake and not as important to meter the amount of CO2 in a spray so in theory a regulator could be used , however once the liquid boils back into a gas will it be cold enough ??

Would the extra cost of a regulator offset the cost of a 1000psi solonoid ? also am I right in thinking that if used at that same size jets a bottle running on 100psi will last longer than a bottle running on 1000psi ? or does it not matter as the jets will limit the flow ??

I want to activate the system via an arming switch and a microswitch set for WOT as the CO2 will only really be used on the track , the WI was going to be for every day use

[NixRX7]

well if you use a syphon type bottle then all you will draw off is liquid.
A syphone bottle has a tube running from the top to the bottom, so it always draws liquid.
If its only for track days then i would use either a 20oz or 32oz tank with a standard on off valve fitted to it, then just run a line out to your solenoid.
You can get these bottles cheap at places that sell paintball gear, for the solenoid just use a standard CO2 one that runs 12v operated off a micro switch.
Just dont let the bottle get to hot, i.e dont leave in direct sunlight or in the car when not in use, as they have a tendency to blow there saftey valves once they get to hot.

Overall its a very simple thing to make, and would be very effective.

[Tintin]

Seeing as you\'ve built systems before , do you know any decent UK suppliers for the valve , adapter and solenoid

[NixRX7]

I used to work in the bottling industry, making up systems for carbonating soft drinks, so i doubt the stuff i used would be much use, mainly as most of it was either 240v or 3phase.
For the bottle go to a paintball supplier like i said, ask them to convert it to syphon feed, 20oz will be aluminium 32oz will be carbon fibre wrapped, get them to fit a ON/OFF valve to it, this will cost you about £20 - £50 depending on your bottle choice.
 They will also sell an adapter to fit the ON/OFF bottle to allow you to fit the hose to it.
These are drilled to take a 1/8 fitting if i remember correctly (used to play a lot of paintball)
Your other option is to use a small welding/pub size bottle, but if its for track use bear in mind that a full CO2 bottle is heavy as its full of liquid.

They will be able to supply the hose as well i expect, if not get some hydraulic hose made up.
Your biggest problem is gonna be finding a 12v solenoid as most are 24v, i\'ll have a look round and see if i can find any for you.

[NixRX7]

Having thought about it, there is no reason you cant just use a nitrous solenoid to control the CO2, i am not sure what pressure NO2 runs at but it would be worth looking in to it as NO2 solenoids will be cheaper then buying a cryo one.
Try here for the NO2 ones

http://www.turbobits.co.uk/acatalog/nitrous_and_fuel_solenoid_valves.html

This firm also sells bottles as well, give them a phone, from looking at their site you could get everything you need off them

any other questions just fire away

[mattmaclennan]

What if you managed to freeze the water in your radiator? CRACK HISSS puddle? They are only plastic end tanks on 3rd gens. Just a thought. The CO2 spray bar idea is a good one. just wonder what the added weight to horsepower/engine safety ratio is?

[Tintin]

Point taken about the radiator , already decided it wasn\'t really a viable solution , hopefully I\'ll be able to make it work on a CC radiator as I\'ll have a better idea of how cold things get by then

I\'m sure the spray bar will be worth it though , engine saftey shouldn\'t be an issue and weight sould be kept to a minimum now as I\'ve opted for the 20oz bottle option , as for power gains we\'ll just have to see , the kit will come into its own on days like last sunday at pod were everyones cars seemed to be struggling a bit with the heat

[NixRX7]

I doubt you could ever freeze the radiator, the water would have to be stationary in it for a start, and the heat generated by the RX7 engine is immense.
You would only ever get it to cool down a bit.
Your best bet is to use the spray bar on the intercooler, or make up a pipe within a pipe and fit it on your induction pipes, then vent the co2 along it to cool the intake charge.

[Tintin]

Right things are moving along nicely now , I\'ve been passing emails back and forth all day with Richard at Turbobits ( thanks for the link NixRX7 ) and we have come up with a pretty good solution

We\'re going for a 20oz bottle with valve and adapter to suit
Braided steel line from bottle to engine
N2O solenoid
Spray bar kit that he sells , its supposed to be a water spray bar but it will work fine

By the way he sells Aquamist kits about 10% off RRP , I\'ve only seen them cheaper on flea bay ( and you can\'t always trust them )

I take it that I\'m right about this not affecting A/F ratios ?? maybe I should change the title of the thread

[mattmaclennan]

If you reduce the air temp the temp sensor in the UIM will pick this up and the ECU will adjust the fuel and timing acordingly. As long as your car runs sweet on a cold damp night, it should run sweet with the charge cooling.

[Tintin]

Only problems I\'ve had with its running is the fact its running too rich at the mo and I\'m losing some power , thats why I wasn\'t bothered if it leaned out a bit

[NixRX7]

How long where you thinking of running it for ? if its something you will be using a lot you may be better off going for a larger bottle, as a 20oZ drawing liquid might not last long.
If its just for track days you could always take a big bottle (pub size) and refill the smaller one when it emptied, if you intend using it for road as well, and lets face it you probably will, then you might be better off going for a 5lb bottle (big nitrous size)

Glad that link helped you out, and good luck, post some pics when its all finished

[Tintin]

Quick update for you , all the parts have arrived and are almost ready for dispatch , Richard has just got to drill the 0.3mm holes in the spray bar , hopefully I\'ll have the bulk of the kit installed by JAE , I\'m not ordering the pipework untill I have choosen my mounting positions

Regarding how long a bottle will last I\'m trying to find out how many holes the spraybar will have , I\'m sure I\'ve seen a formula somewhere for working it out , the kit is only really going to be used for 1/4 mile so as long as a bottle will last for 13 secs I\'ll be okay , looking into the possibility of running 2 bottles and taking a bigger bottle with me to refill them , we\'ll see how we go , the thing against one big bottle is the weight . Obviously I\'m going to play with it alot when its first installed but hopefully once the novelty has worn off I\'ll just use it as intended

Mind you I can see me sticking a purge valve on it just for effect then I may be hooking up a bigger bottle , I\'ve actually got an old fire extinguisher which I was origionally going to use , might see if I can get an adapter nut so I can hook it up for messing about

Also today I\'ve installed fans to the back of the intercooler to help the air get pulled through and stop hot air getting pulled back through , I\'m determined to turn this stock interheater into an intercooler