So then gents

I'm considering adding a small injector into the intake of my charger to get some cooling of the charger but mainly to improve the atomization of fuel to air which I would hope should improve power and economy

Surely you bunch of turbo nutters have already tried this ? Not with water / meth but gasoline in small amounts ?

biggest issue I know of for a turbo pre injector is you must target the injector so it sprays at the compressor nut,. this means the fuel doesn't smash into the blades at 100K rpm it hits the hot nut and evaporates to small enough droplets to not cause damage ( or at least rapid damage)

Not an issue with a roots charger as the blades are running so much slower and are much more substantial

surely this must have been done?

 

I'm doing it (water/meth) on my electric supercharger ...into the volute. Works well

 

Cool ( no pun intended) what sort of flow rate and pressure are you using ?

 

Don't remember the exact size I have there but I used this table as a guide (allowing for rotary flow/hp) : nozzle_selection_guide.jpg (2183×1721)

Pressure is around 250psi

 

I was more thinking regular gasoline for the injection and not water / meth though. As I don't want the extra tank / another system . So was thinking to have a small single injector on the entrance to the charger and plumed to the same fuel feed as the regular injectors and wire it in paraell with one of the upper injectors

 

Have never heard of that being done but it sure sounds super dangerous.
Also: that would be WAY less effective than w/m.

 

Cosworth used to do it on the Indy cars.
about 1/4 of the total fuel flow was injected pre compressor ( under boost of course) it used to reduce the compressor temps a lot . A kind of chemical intercooler if you will, as well as really helping with combustion as the atomization was excellent
admittedly this was with methanol so a bit different

I've done it before on a couple of projects where I made up an injector mount like a Mercedes hood emblem. so you had the jet in the middle and fuel piped down 1 leg of the star so you could mount it into the intake just in front of the turbo.this was done on a disel and a gasoline engine and reduced charge temps and boosted power on both, with the gasoline engine it was effective enough to allow ice to start forming on the outside of the intake pipes

I've never done it on a roots supercharger though but I can't see it not working. I was thinking of fitting the smallest injector I can find and piggybacking the wiring to one of the yellows so it only chimes in at high rpm

 

methanol is a completely diferent story. it has VERY large latent heat. simmilar to water. Petrol has almost no latent heat. on roots they are comonly used to increase sealing.
do you have no intercooler post the M90 ? you can have condensation there.

 

Hello Milos

good to speak to you again

you're correct petrol isn't great as a cooling medium
I'm really thinking to try this to the better compressor sealing and the better combustion from the better atomization

its a TVS R900 charger and there's a decent intercooler brick with a good sized low temp rad and 12 ltr/ min pump for the water

I've taken post intercooler temps on a pull and its down in the high teens ( Deg C) so temps are pretty good

 

To me, the only concern with such setup is if you can make sure that there is no way for pooling to occur. as than you will have to relie that you will evaporate all of the fuel and also that none will condense.
What air flow / drive ratio are you running on it ?

The water pump sound quite low flow TBH and can be the source of your problems. a cheap pump you can use is the Tesla Model S pump. ~150£ and it measures 38lpm in open flow, for 0.6barg restriction it flows 26llpm and than maxes out at 07barg at 28lpm

Tesla water pump - EVcreate
Connector kit water pump Tesla Model S / Model X - EVcreate
you can run it simply powering it with + and -

 

thanks for the pump recommendation I have a 30 ltr/min pump waiting to go on - that said I don't really have a temp problem with the cooling system I have as I've seen 16 °C on a WOT pull with a thermocouple in the port ( lower inlet manifold vac port point)

I'm currently at a 1.85 :1 drive ratio on the charger so this needs addressing so I have some pulleys to design to up the ratio

the exercise if more about improving combustion

you are right though at low air speeds there's a very real possibilty of it dropping out of suspension and puddling up on the intercooler brick

 

oh, teens, not tens :D well that is great , but than I would really be careful with the pre-injection. no matter what fluid type you would try.
but this is a great reasurance that i should have overheating problems either on the TVS-R1320 (same drive ratio as yours). finalising the intake manifold soon. other thing came up front so had to put the SC on hold