Dyno results, need alittle help
Turbo Mini Forums

Hopefully one of you guys will have the answer to this.

I had John Sleath work his magic this morning. Had a good few runs, sorted the fueling out then turned up the boost. Once the boost was turned up it has a big lean off then goes back rich. This gives the wavy read out at the top. John said it starts to happen as the wastegate is opening.

Max output for the day was 114BHP at the wheels which I think was 10psi. We stopped after finding out this problem on high boost.
Currently running a safe map at 4psi until this problem is sorted out.
Any thoughts are welcome.

Weak actuator spring causing the boost to fluctuate rapidly? Float bowl running out of fuel?

Weak carb spring?
what oil have you got in it?

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

Me and john did think that Andy so I suppose the only way to rule it out is try another actuator. Float bowl should be getting plenty of fuel as the pressures correct I think.

Pretty sure it's a standard turbo spring but I could be wrong. Just SU oil in the dashpot.

Is the plendinidum gasket on the wrong way round, stopping the pressure rising in the carb.

There's nothing fundamentally wrong with it as it's working ok on 4psi.

What wastegate actuator is it? How are you bleeding boost off? What pressure does the actuator start to open off it's seat? What turbo is it? How much preload on the actuator?

lean off pipe fitted???
also try the t peice trick, just a hunch ive seen similar in data logs when i cocked something up

Yes i moved to the darkside

Instagram @jdm_brett

plug gaps ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

It's the standard actuator that comes with the GT17 which is the turbo I'm running. Not sure what preload I have on the spring (not sure how this is measured)
I am just using a standard bleed valve, I'm not sure when the wastegate starts to open.
The lean off pipe is blocked off at the moment. I will take a photo of my carb set up just to make sure I have all the pipes on the correct way

Have you blocked the over boost thing in the plenum?

Good call Nic!

If something is worth doing, it's worth doing half of.

How and where is this over boost thingy on the plenum?

Av whatsapped you. But its behind the gonzo nose on the plenum, you can just pack the spring out with 5p's as a quick fix.

If something is worth doing, it's worth doing half of.

5p's blimy this forum is changing it would have been washers back in the day 😀

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

I think mine still has 5p's in it from about 8 years ago, wonder how much interest I've missed out on?

Think i sold mine with the 5ps in lol, should have asked 25p more lol

Yes i moved to the darkside

Instagram @jdm_brett

Right guys had a look at the over boost thing, it's already been welded up.

Is there a poppet valve in the throttle plate?

Dazed and Confused....

I will check this tonight

Yes i moved to the darkside

Instagram @jdm_brett

Ah, true...

Dazed and Confused....

Could high boost maybe forcing its way past the gasket on the plenum? i notice some blue gasket that looked to have been forced out of the area between the plenum nose.

could be, maybe the surface was oily and the gasket hasnt taken.

could be, maybe the surface was oily and the gasket hasnt taken.

notice today that my pipe from the inlet manifold to megajolt had come off, could this cause the wave?

We must have knocked it off moving my boost controller.