4AGZE extra injector before S/C

[craigy]

Hey Guys,

I've been contemplating the idea of mounting an extra injector before the supercharger on a late model smallport GZE. My engine builder has done this a few times before on V8's and big sixes and has had improvements in air temp (before/after) of up to 80deg Celsius.

It seems like a great idea and well worth doing, it should prolong the life of the S/C and increases in power seem likely.

Just wondering if anyone has done this?

Also peoples thoughts/critisisms on this arrangement.

cheers
Craigy

[oldcorollas]

fuel pooling in intercooler.

[psychofox]

if you mount the injector before the supercharger you will be compressing a volatile mixture, and the attempting to cool this mixture in an intercooler (which as oldcorollas says, will cause it to pool).this will create a nasty fire risk for yourself.

The other point is that you are probably not mounting the injector at the best point anyway. What you are ultimately trying to achieve is reduction in the air temp going into the cylinder. Mounting the injector before the S/C is trying to reduce the atmospheric air going into the S/C, which will be minimal. If you mount the injector AFTER the S/C then the fuel will be able to reduce the compressed air temps. BUT you will have to worry about fuel pooling in the intercooler - possible fire. If you mount the injector after the cooler, just before the inlet manifold you will cool the compressed air charge and not have the risk of burning your car to the ground.

Hope this helps.

[oldcorollas]

or you could use a throttle triggered water/methanol spray. a bit safer, and depending on the energy used for evaporation, might be better (water takes more energy out).

[craigy]

Fuel pooling in the cooler sounds like a big turn off! I really dont like the idea of a couple of litres of fuel splashing around in the front of a race car!

Lowering inlet temperature is my main concern considering my engine runs quite high compression. Adding 12-14psi to it brings it into a dangerous zone.

I thought runnng it before the S/C would help with cooling, therefore prolonging its life. Maybe i'll just keep a couple spare!

[jonra23]

As oldcorrolas has said go with a series wired supercharger clutch/throttle position switched water/methanol or just straight water injected before your supercharger.

It will increase your effective boost by sealing better and giving lower charge temps also will help prevent detonation, without the risks of fuel in intercooler.

Regards
jon

[Hen]

You have a good intercooler (well big anyway) so I'd hope inlet temps really aren't going to be a problem.

However water injection pre-charger would be a much better idea.

I also wouldn't worry about SC life. Even at that boost I'd expect it to last ages before anything untoward happens to it.

Hen

[jezza323]

i also vote for water injection pre-s/c, will cool down the charger, air temps and give u a slight CR increase (the water takes up some volume in the compression chamber) which will give a bit more power

there are some great threads on water injection on turbo setups on the ausrotary forums, havent been around here that much so i dont know what threads there are on the subject here

[Ben Wilson]

I've got a water injector before the supercharger in my mr2, it seems to work OK. I haven't done any before/after testing though..

[WindeX]

Ben - do you have any details on this setup.

[mrshin]

1. BANG! as has already been mentioned
2. Why on EARTH would you want to make a GZE run even richer?
3. I'll put in another vote for a light quantity of water if you want to spray something in there, just don't overdo it..

[Ben Wilson]

I was using a surflo pump, an ebay fuel pressure regulator, a Jaycar digital pulse adjuster and a Nissan fuel injector. I mixed a little corrosion inhibiter with the water so the injector wouldn't rust.

I had to run the pump at 8 bar to get a decent mist out of the injector, but is seemed to handle it OK. I was running the injector in the 'elbow' of the supercharger inlet pipe.

[Koffee-Black]

Off topic a little, i have some 7mgte injectors, can I throw them in the 4agze? Will it run ok?? (Assuming this is before I get the haltech and tune)

[Ben Wilson]

It might, but why bother?

[thechuckster]

see Mr Shin's point 2 - why waste even more fuel?