[Mk2] [Turbo] Compressor Surge

[bobhatton]

Not sure on compression ratio but the car is run on shell v power and I think it boosts at 1.6bar max using a gizmo boost controller.. And like has been said if it was knocking Ryan wouldn't have let me leave in the car

I don't think its knock as when it's starts to surge the dump valve keeps going and it starts chattering like the air passing the turbine on the turbo and won't go any higher up the rpm but if I let off to say half or quarter throttle it will..

If I go through the gears full rpm into 4th and 5th there is no problem it's only when it's under heavy load..

1.6 bar is quite high boost and you should have low compression pistons if on road fuel, find out what is fitted as this is very important.

The dump should not be opening up so go back to a stock and try it.

To map an engine for road uses correctly will take days or even weeks but most mappers today only spend what 4 hours, they miss so much out through lack of knowledge.

[mr2_rich01]

They are cp Pistons just can't remember the compression ratio, I'll try the standard dump valve and see how I get on.. That's if I can find it thank you for your help! I'll let you know how I get on!

[jimGTS]

Last time I saw Ryan he had come back from a trip to Dubai mapping cars.
Being flown out and put up in 5/6 star hotels by his customers.

He gets flown all over the world doing this.

That doesn't strike me as something people pay for if they are not knowledgable in their field.

[bobhatton]

They are cp Pistons just can't remember the compression ratio, I'll try the standard dump valve and see how I get on.. That's if I can find it thank you for your help! I'll let you know how I get on!

Unless they are custom made they will be 9.0:1 CR, far to high for 1 bar boost on road fuel
So if you are running 1.6 bar boost the timing will have been wound right back, and this will be like anti-lag and giving more power to the turbine wheel and spinning the turbo much higher than it should be at that point.

Your engine design and build are wrong for the boost you are running.

[ashley]

CP do off the shelf 8.5:1 pistons- and depending on headgasket choice, and headwork this could be even lower. Who built the engine? Would be worth checking what parts they used before you panic!

[mr2_rich01]

me and my dad built the engine but it was aroud 3 years ago so have forgotten what compression ratio the pistons were, we used a rev 3 standard metal head gasket, basically are you saying i need a different turbo i.e a bigger one to create more power at lower boost? say a GT3076?

Regards Rich

[ashley]

are you saying i need a different turbo i.e a bigger one to create more power at lower boost?

No, it's a well proven turbo for your engine and it's difficult to believe it's surge that is your issue unless you've done something odd, like inlet and ex cams the wrong way round, or well out of timing...really difficult to say without lots more info, and the engine in front of us to check/ try things.

I'd be totally checking the wastegate and BOV set ups, check they are totally working as they should be, check all the vacuum lines, makes sure you've got the vac lines plumbed to the right places, and the actuator/ solenoid correctly plumbed in.

We need to check it is actually surge, it sounds like you're hearing the BOV and wastegate activating at higher loads...that may not be surge related.

[gazrev1tubby]

What a:r is the turbo, and what size/make wastegate are you using mate?

[mr2_rich01]

Hi guys thanks for all the replys this is the turbo kit I have http://www.atsracing.net/Parts/Index/TD06 and bought it second hand from a guy on here hope this helps..

[2mad]

Just so were on the same page do you mean like this ... https://www.youtube.com/watch?v=nCj6Spwl1CU

[mr2_rich01]

that is exactly what it does and sounds pretty much exactly the same as that when it does it..

[2mad]

This is one of those times I new what you meant but I know very little about engines and mapping mate .. sure someone can help now they now the problem ... i hope

[mr2_rich01]

appreciated cheers dude