Sam's build thread

[sambb]

Alright my next low cost mission/mod is going to be re organising the passenger side engine bay. Once I get a fresh Ko3s core into the modded turbo, I'm planning on running boost pressure fed water injection pre compressor. So what I want to do is remove the standard air box and in that area make the lowest possible casing for a new battery - a Full River HC20 which will be mounted lying on its side below the ECU. The air filter will then move to the front and sit in a sealed area behind the headlight fed by the same duct that it has now and from anywhere else that I can find cold air.. That should hopefully allow me to move the MAF along a bit towards the new air filter box and allow me to put in line a custom section that will house the water/air nozzle. My boost pressurised reservoir for the injection water will be an identical unit to the coolant tanks we use so will look stock in that respect. If there's not enough room for that then the battery will go to the boot. I don't really want to do that because I don't want to take too much weight out of what is already the light front corner of the car but if packaging all this is a problem then that's ok. When I de mufflered the exhaust and put on an aluminium pipe I took 7kg out of the back of the car and the 7kg battery will at least perfectly offset that if it goes to the boot.
Its a very good way to give small turbos more top end, gives a variable water injection rate that matches load without the expense/clutter of controllers/wiring and the misting nozzles used atomise the water to a far greater degree than pump pressurised nozzles that don't used pressurised air to 'cut' the water droplets at the nozzle tip. There are commonly available misting nozzles from spraying systems but I know of a guy who modifies them specifically for this purpose (mazda rx7 SP) so i'll have to get back in touch with him. Everything in this WI system is dirt cheap its really the nozzle that you can't skimp on if you want good results and turbo longevity.

[sambb]

Water Injection Rice Racing.wmv - YouTube

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edit: props to Julian Edgar. This image was lifted from one of my bibles, his book '21 Century Performance'. Hope that's ok.

[HaydEn]

Sounds like an awesome setup.

Looks cool as on VR wheels

[sambb]

Thanks. Yeah it doesn't look half bad with those rims sitting on the start line.
You gotta join - you can't live that close to the track and not get into it! Join at Home - MG Car Club Newcastle in feb for 60 bucks I think it is. Then get you CAMS L2S by just filling out the form. Fire extinguisher/helmet/tow points and stickers and your set. They do 12 hillclimbs a year and usually only 60 bucks entries. Your R32 will howl around there.

[metalhead]

Yeh, I'm thinking the same thing, I've avoided Facebook up to now, but might have to finally start using it.

You may be onto something with your observation about wheelbase, I'm surprised to find through Google that my wheelbase is only about 25mm longer than yours, 36mm less than an s15, and 157mm shorter than the Megane! But there's a lot of weight and length (almost half the overall length of the vehicle!) outside that wheelbase, which is generally not regarded as an ideal situation...

I have a complete rice racing water injection setup from a long dormant project if you're interested... Not sure if I'll ever get back to it if I'm honest (rwd 323 with 12a bridge port turbo rotary engine). Water injection is good stuff. I have a water injection setup (with pump instead of boost pressure due to suck through carb) for the supercharged MG Midget too.

[sambb]

Jeez how many cars do you have hiding away. Tell me more - the rice racing setup you have Is that a boost pressurised system with an air and a fluid feed to the nozzle or a pumped system? If its a dual air/fluid nozzle I'd definitely be interested in that! I ran pumped pre throttle body injection on the last car to make up for my little side mount intercooler. It did well at bringing temps right down. That's not really the priority now, its to get the turbo breathing a bit deeper above say 1.2bar. I'm not that keen on pre compressor pumped water injection because from what I can gather you definitely need an expensive controller, special nozzle mounts to fire the fluid straight at the compressor shaft nut and potential blade damage from errant droplets. If the boost pressurised pre compressor system doesn't work then i'll go to a pumped direct port system.

[metalhead]

That's a dangerous question! I'm probably insane, but on the upside I'm not likely to run out of projects any time soon, and as you've probably gathered, they have enough variety to keep me on my toes. Always want to try/learn something new. Just don't ask how many guitars I have.

It's a really nice Rice Racing boost pressurised system, alloy tank, with air and fluid feed to the nozzle, designed to sit pre-turbo. I did have a quick look for it at my father in laws (in my 40' storage container with contents from our garage when we lived in Sydney, including two cars) earlier this evening and I'm not totally sure where it is, but it's in there somewhere... Realistically, you might be better to buy it elsewhere if you can, because I'm not totally sure I'd want to sell it anyway, but if you get stuck then send me a pm.

Is the coolant tank you refer to a pressurized tank? A normal coolant overflow tank probably wouldn't work great, you need something rigid and well sealed - designed to hold pressure. I think from reading you're talking about putting the nozzle after the maf, and you definitely want to do that. The fullriver batteries are good too, I had one that was used in several different cars including the Vette over about 5 years, and I suspect still had life in it when I chucked it - I discovered a faulty terminal about a week after throwing it out.

[sambb]

Cool. No worries I wouldn't want to part with it either. It'd be perfect for the midget yeah? The coolant bottle is a pressurised unit with a refillable pressurised cap. I'll have to check what pressure it operates under but I'd imagine it'll cope with 25 or so psi pretty easily. It has a top side small hose fitting that will be perfect for the air pressurisation (its normally the water return) and the bottom side fluid fitting is nice and small too. Its also really well baffled so it'd be difficult for water to get up into the boosted air feed if for some reason a one way valve failed and it saw vacuum. I'm pretty keen to keep the bottle/plumbing all in the engine bay so that there is a really quick response time in the system. Where I can I'll use pneumatic hard line and push fit connectors too.

[metalhead]

Sounds like you've got it worked out. The Midget uses a suck through carb, so I figured a boost pressurised system (when my boost has fuel in it) probably wasn't a good plan. So I have an AEM pumped system to go on it.

[sambb]

ah yeah I've got you. Penny just dropped - The boost signal hose would be full of explosive stuff that you'd be pressurising into a reservoir. That could go bad. gotcha

[sambb]

hillclimbnsw.com have finally updated their site with the Rd7 report: http://hillclimbnsw.com/report-2017-...ood-hillclimb/

outright and class breakdown results here: http://hillclimbnsw.com/2017-08-06%2...%20ver%202.pdf

that's some nasty tyre torture on that outside front. I'm going to go back to 205/50/15 fronts to get that under control.

[sambb]

I just got these wheels for a good price from Hayden. They are 15 x 7 Enkei RP01's. I'm debating whether ill get them stripped and repainted a deep maroon/red or just keep them white and save the bucks. The plan is that i'll swap my A050 semis onto these for the track, run the Mk3 Gti/Vr6 15 x 6.5 rims pictured on the car above on the road with probably some Toyo R1R's (these will become my wet tyres if it rains for the track) and i'll sell the Polo's OEM wheels to finance the tyre purchase. The VR6 wheels will be fine for the street - i'll need more sidewall as i'll be on 500-450lb springs soon and the cost of 195/55/15's is a pittance for some pretty premium brands eg federal 595 rsrr's and toyo R1R's etc well below the price of Re003's for 16's.

[metalhead]

I reckon they'd look awesome on your car in grey or black with a machined or polished lip... Just saying! But they're track rims, so function is more important than form - I'd probably redo them myself on the cheap if it was me and I didn't want them white. Guessing those would be pretty light? Should look good on the car.

[sambb]

So this is the air atomising nozzle that i'll be using for my boost pressurised water injection system that will go pre compressor. The main body of it takes in boost pressurised water on one side and boost pressurised air on the other. The internal bits basically squirt the water that is then blasted from all sides by the air nozzles (like a commercial spray painters gun but at lower pressure) that make it fog like in size. Its a spraying systems SUE15B which is the narrowest angle (45 degrees) and least penetrating spray pattern they make. At 5psi, 10psi and 20psi of pressurisation (same for air and water) it'll discharge 1.0, 1.4 and 2.0 gal/h.
Mounting it is going to be the tricky bit. The existing forge TIP will need a 90 degree elbow put in the end of it so that the air feed will come from the front. In the following linked CFD paper I found, if you go to pages 39 and 40 and look at air velocity, dynamic pressure and turbulence you'll see some stuff about how air flows around a bend.

http://ethesis.nitrkl.ac.in/5976/1/E-143.pdf

I'm thinking ill weld a fitting onto the elbow so that the water shoots down the pipe towards the existing opening of the forge TIP. This will put the water into an area of high velocity and at the exit of the bend, mqximum turbulence to keep the water in suspension and mixed well. If anyones tried anything else I love to hear about it.

[sambb]

So I've crunched some numbers to work out if my WI nozzle will flow the correct amount of water. I've been checking in on a few interesting threads on aquamist.co.uk and the general consensus is that once modded, you need to inject water to the tune of 10-15% of total fuel flow.
I have std 380cc injectors that are operating around 85% duty cycle (that's an assumption and could be wrong - guess I should look at some logs). 85% of (380cc X 4 injectors) = approx. 1292cc of fuel flow max. 10% water of that = 152cc/min, 15% = 228cc/min.

My nozzle runs:
5psi - 1.0 gal/h = 75cc
10psi - 1.4gal/h = 105cc
20psi - 2.0gal/h = 151cc

Being a boost actuated system it is not directly pegged to fuel flow eg not running off an injection signal like a pumped system might. But boost should mimick load and therefore fuel flow quite well. The above numbers suggest that at 20psi (close to peak boost/peak load/peak duty cycle) i'll be running bang on the minimum suggested percentage of water to inject, which I'd prefer to running at with pre comp anyway. The only question is whether or not the water curve of the nozzle matches the fuel curve within that 10-15% range below that full load point. If it does then I can switch the water injection on early, if not then i'll have to switch it on later where I know it is in step, but from a theory stand point at the moment it looks like the nozzle (at least near full load) is reasonably well matched.

When I was running a pumped post intercooler/pre throttle body nozzle I had found that the switch on point had to be adjusted higher and higher until it was coming on at just under 1 bar. This was because with a small turbo you can actually run into close to full boost quite easily (eg high gear overtake from a moderate speed) and inadvertently switch the injection on when rpm are artificially low. This had the effect of sometimes being a little doughy but this was more to do with injection location than anything else with water probably turning into steam in the cylinders rather than in the compressor as it will with pre comp injection.

On the aquamist forum lots of people seem to have had success switching the pre comp injection on at or just above the standard peak boost that the car came with so 9-11psi might be the go initially. Next time I'm on night shift I'll plumb it up and run it off regulated compressed air. I'll try to get a vid of it in action.