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volvo turbo bypass valve
matt_gsxr - 25/6/11 at 08:37 AM

A bit of a volvo (or saab) turbo charger question.

The td04 turbos on these models have a bypass valve which operates as a recirculating dump valve.

I think (but am not sure) that when in a Volvo T5 this control line/hose to this valve comes from the plenum (after the throttle plate), but I am not certain.

Any experience of the best way of plumbing this in with ITB's. I have had it getting a feed from the outlet on the turbo (same as wastegate output) which but I don't think it is right (I do get small ~120ms ~1psi increases in boost when the throttles close on my ITB setup).

At the moment I am installing a boost control solenoid (plumbing it in so that it bleeds off boost pressure from the wastegate, which is the standard MS method). So I started thinking about this.


Matt

indykid - 25/6/11 at 08:44 AM

It needs a vaccum feed after a throttle. I can't see it matters which runner you take it from, but it needs to be vacuum.

The comp cover will never see vacuum so the valve will never open. The wastegate actuator works on positive pressure, not vacuum

ashg - 25/6/11 at 08:51 AM

on the saab it goes to the inlet manifold after the throttle body

matt_gsxr - 25/6/11 at 08:59 AM

Cool, I was coming around to that point of view, but wasn't sure.

I will replumb.

Thanks guys

Matt

Volvorsport - 25/6/11 at 10:49 AM

junk it .

make a plate to cover it , and put a proper recirculating valve on .

matt_gsxr - 25/6/11 at 11:12 AM

quote:
Originally posted by Volvorsport
junk it .

make a plate to cover it , and put a proper recirculating valve on .


I thought I'd get that suggestion.

Is that because they leak boost, or is there another reason?
My boost requirements are pretty minor (only about the same as stock say 1atm max), so I was hoping to save the money and stick with what Volvo intended.

I could just dump to the atmosphere as I am not using a MAF, but I don't really want the crude noises (aiming for the Gulf liveried, turbo-bike-engined, full cage, sleeper look!).

Matt

ashg - 25/6/11 at 11:45 AM

i dumped mine and just put a bailey dv26 on. dumps straight to atmosphere

Volvorsport - 25/6/11 at 12:59 PM

itll be trying to vent out of your air filter , much better to dump just before the throttle plate .

they also do go wrong , ive got one on my car and it is noisy through the air filter .

matt_gsxr - 25/6/11 at 01:35 PM

I'm a bit confused. Don't all recirculating dump valves end up potentially flowing out of the filter?

I guess I have another upgrade in my future will keep an eye on e-bay. Maybe even go for the chavtastic dv26!

Matt

Volvorsport - 25/6/11 at 03:21 PM

yes but since youll most probably have the air filter right on the end of the turbo itll be noisy and reverting right through the filter .

its fair to say that most recirccs would revert through the filter , if its been metered air tho , its not really what you want .

ive got a baileys dump valve somewhere !!!

matt_gsxr - 25/6/11 at 06:39 PM

I get it now, thanks for being patient with me.

So, basically in the Volvo you have filter, MAF sensor, some tubing and then turbo (with its bypass valve). So when the bypass opens the reverse flow due to the expansion of the compressed air in the dead space of the tubing and intercooler after the turbo is sort of stabilised.

You are correct that in my install the filter is close to the turbo inlet (maybe 12inch). I don't have a MAF.

Up until now I think it was plumbed wrongly, so probably wasn't even opening, I will investigate its behaviour now it it plumbed correcyl.


FWIW: I have a plenum from a Pulsar GTiR so there is already a location to fit an external dump valve.
plenum in place
plenum in place

Thanks,

Matt