Re: Pre and post turbo injection in an audi b5 s4
 

any update?
my car is still in winter storage until March

Re: Pre and post turbo injection in an audi b5 s4
 

I have been working on it and tested it.

Currently injecting 350cc post turbo and 50cc pre-turbo @ 10psi till 18psi.

Ambient temp is 15C. Injecting 400cc @ 18psi result 35DegC on first run climbing to 45DegC on consistent runs.

After throttle is closed and cruising, air temp keeps a steady 15-20DegC. Note this is all without intercooling.
The crazy thing is that with water injection I am loading engine on boost from almost stoich at low boost while from 10psi+ running 13.5AFR and lots of advance !

Now I am working on wheel alignment issues so until then... no updates.

Next up... increasing Pre-turbo injection to 150cc total of 500cc

Re: Pre and post turbo injection in an audi b5 s4
 

Is there a way to block the post turbo jet to see the effects of only the pre-turbo? I'm installing a .3mm pre-turbo to start but I forget what the cc rating is.

Re: Pre and post turbo injection in an audi b5 s4
 

It is very easy to block the post turbo jet. Just a tap on the water line makes it running pre-turbo only.

The only issue is that I don't want to inject much pre-turbo so I am trying keep the post nozzle fixed while changing pre-turbo flow.

When I reach my goal of lowest air temp at max boost of 18psi, I will make 3 tests.

1. Post Turbo only
2. Pre-Turbo only
3. Post+Pre Turbo

With AFRs used / Ignition Advance / Air Temps @ Throttle Body / EGT readouts / Spark plug readouts including datalogs and graphs

Re: Pre and post turbo injection in an audi b5 s4
 

Is your pre-turbo progressively controlled by the FAV or is it running off of straight pump pressure, non-progressive?

Re: Pre and post turbo injection in an audi b5 s4
 

I am using the AEM progressive control system. Starting injection at 5psi and full at 10psi. Both nozzles use the same pump system and are connected with a Tee-fitting.

The only difference is that the pre-turbo nozzle has a custom made adjustable check valve in order retain it from injecting at low boost. The drawback of the nozzle is that it is more bulky than stock due to the springs.

Check out the attached Plug at last tune. Heat Range is 6 gapped 0.7mm.

AFRs are :

17-19 IDLE
16.5 - 17 Cruising
14s 0-5psi boost
13.5-13 6-18psi boost

Re: Pre and post turbo injection in an audi b5 s4
 

Seems to be a lot of soot on the firing ring.

Re: Pre and post turbo injection in an audi b5 s4
 

I agree ! And that is at 13.5 AFRs on load.

It surely will work with 14 AFRs

Re: Pre and post turbo injection in an audi b5 s4
 

Did you tune engine ignition on a dyno?
Did you try reaching MBT on the dyno as well?

Re: Pre and post turbo injection in an audi b5 s4
 

No dyno, tuning is done on street and datalogging.