CT12B Turbo

[G-man11]

Hi Guys,

Need some opinions.

I have a Golf 4 GTi 18 20V which I custom fitted a CT12B diesel turbo on. I had Turbozone do a full repair on the turbo which did 10 000 km at max 0.7 bar boost.

My theory is the following:

This turbo (being a diesel turbo) runs at 3000 rpm engine revs at 120 km/h. On a patrol it will be say 4000 rpm or more when driving casually.

Does a turbo suffer if is running faster than designed revolutions all the time and by doing this damaging seals and bearings? Does it create allot of heat under these parameters?

Your experiences is appreciated.

Thanks Gents

[Jetta2]

The turbo will be spinning a hell of a lot faster than the engine revs from idle to motor's redline.

Turbos spin up to 120 000+rpm when boosting.

[G-man11]

What I am getting at is, if the turbo from a diesel is designed to be spinning at 40000 rpm in normal conditions when fitted to a diesel motor, will it have a negative effect on the turbo if its now spinning at 60000 rpm under normal conditions fitted to a petrol motor?

I am trying to ascertain whether a turbo can handle having to spool a 3rd faster then what it was designed to do.

Thanks

[THANAS]

The turbo speed isn't determined by the engine speed in any way (aside from where it spools).

Find the compressor map and see the pressure ratios it can achieve and at what flow, and do a few calcs to determine whether the turbo will be operating within its limits (speed/surge/efficiency etc).

[panic-mechanic]

The application where aturbo is used being diesel or petrol does not determine the final rpm of the turbo. As mentioned that is determined by boost level and compressor profile. But to give you an idea , toyota uses th same id ntical turbo ct26 on a diesel 4.2 landcruiser, a supra and mr2. So it really does not matter whatbit off originally as long as it stays inside it's max rpm and efficiency profile it will be fine. And yes turbos run between 120 000 and 180 000 rpm when theynare producing full boost. Not the 3000 or 6000 the engine ismturning over.

[Killerwatt]

You are correct in saying the turbo will run a bit faster on your application. At your current boost it woud be around 120k rpm at the coast, bit more at altitude. Thats fine for the bearings used on the ct12.

The Ct12 is not exactly a good spec turbo for the 1.8t though. It has marginally bigger wheels than the stock K03, but the trim on them is suited for a lower flow and higher boost engine. What was the reason for using this turbo?
What are your power goals?

I see you have a forged motor already. With a better turbo and supporting mods, you can easily double your current power.

[G-man11]

First of all thanks for all the info gents. Reason for using this turbo, good question. Trying something different and curiosity. Call it a project if you want.

The turbo for 10 000 km first time around. Total recon and new shaft done now. It never saw more than 1 bar boost in short bursts only. So something is causing the turbo to struggle and cause seal and shaft damage. I know there is many reasons that can cause this but all the obvious boxes is ticked off.

All opinions is pointing to wrong turbo at this stage. So seems my only choice is to boost the crap out of it till it gives and slap a t28 or bigger on.

Do you guys think it's worth it to machine the exhaust side and playing with turbine size or trimming it?

[panic-mechanic]

No Just put a properly sized turbo on it once. Costs less to do it right once instead of several iterations.

[Killerwatt]

Agree with Panic. Unfortunately that turbo spec is way off. No point fiddling with it.

Again, whats your power goals

[G-man11]

Well is there ever enough power. My plan from the beginning was to squeeze as much as I can from normal pump patrol and try and be as reliable as possible.

Now that I know a new complete turbo mod is on the table what turbo would you guys suggest?

[Pynoxim]

GT3071

[JonathanT4]

Me thinks a GTX2871 gen 2 would be great!

[G-man11]

Will go have a look see. From what i gather on the net these turbo's are kinda big. Hope it will fit without having to cut into body.