Bit of a newbie here but I guess this is the right place to ask about my problems I am having.

First of all I have a ST205 model Toyota Celica GT-Four that is my weekend/track car. Your typical rally car, awd, 2 litre, turbocharged job. I recently had a blown turbo thanks to the fragile ceramic turbine. Had the turbo rebuilt which is based on a Toyota CT26 unit which is used on many Toyota vehicles of the time ranging from Land Cruisers to Supras.

I ended up with a Turbo Technics Hybrid turbo which was their latest revision with a bigger compressor wheel (66mm to 70mm) which is also billet. This is where my problems started.

Once fitting the turbo it became apparent that I was surging from 4.5k to 5k rpm but absolutely fine before and after that rpm range. I tried many things like removing boost solenoid, removing dump valve, checking for leaks etc etc. What I did discover is that my boost surge disappeared when I removed my entire intake piping ans filter . From my understanding boost surge is too much air that the engine can eat in laymans terms but by removing my intake it seems to have shown that I am starving my compressor wheel of air? Can that happen?

#ad


The image doesn't really show but the plastic intake pipe consists of two almost 90 degree bends plus it is ribbed in places. Also the metal intake pipe has two take offs for idle control and catch can. The filter is a Blitz SUS which is a metal air filter. Great for airflow but rubbish at filtering!

My plans are to relocate the battery to the boot and run a 3" straight intake, remove all the take offs and give them their own filters and run a cold air feed from the bumper through the wing.

Does this sound logical as my surge was gone without any intake on the turbo or am I barking up the wrong tree?

I have also thought to add a more free flowing exhaust to my setup. I am already using a berk decat with a standard exhaust but it does have a lot of silencers. With a more free flowing exhaust it will help the exhausts gases to escape more quickly but will this add to my problem or make it better as in theory the turbine will spin faster?

Also any tips that do not include major head work or cams are welcome.

Thanks Adam.

 

Yes that can happen it can work both ways, a given compressor cover and wheel size will have a min pressure drop rating for the air cleaner and feed piping. If not it can stall/surge. In general it should have no greater than 15" drop. Does your vac at idle or coming off throttle when cruising change significantly with the intake and filter off vice with it on?

There is also a back pressure/exhuast max vac rating for as well, in general should be no more than 1-2". Freeing up the exhuast after the turbo is usually always a good idea.