944 Dump Valve

[Guest]

ORIGINAL: 944 S2

ORIGINAL: slim_boy_fat

I have just fitted a Forge Motorsport DV to mine, recirc type.

Cheers to the Biscuit. []

and the verdict is ?

Its alright i suppose []

First impressions are that its much better than the standard. Maybe my imagination but i swear it has less lag, much less.

 

[sawood12]

I'm not into the bus sound either. Don't know if i'm missing a trick here but I thought recirc dump valves were better since the high pressure air in the manifold is diverted back to the low pressure side of the compressor thus accelerating it so it's upto speed and ready for when you complete your gearchange and floor the throttle again. All a non-recurculating dump valve is doing (apart from making your car sound like a bus) is to dump (i.e. waste) the high pressure air you've taken the time, effort and burnt fuel to compress and at the same time allow your turbo to decelerate meaning you have a moments extra turbo lag in the pick up for the next gear while your turbo gets back upto speed.

 

[Guest]

ORIGINAL: sawood12

I'm not into the bus sound either. Don't know if i'm missing a trick here but I thought recirc dump valves were better since the high pressure air in the manifold is diverted back to the low pressure side of the compressor thus accelerating it so it's upto speed and ready for when you complete your gearchange and floor the throttle again. All a non-recurculating dump valve is doing (apart from making your car sound like a bus) is to dump (i.e. waste) the high pressure air you've taken the time, effort and burnt fuel to compress and at the same time allow your turbo to decelerate meaning you have a moments extra turbo lag in the pick up for the next gear while your turbo gets back upto speed.

Yeah it is a recirc race one - nice and quiet, the only noise he hears is whoshhhhhhh as the turbo spins up, followed by roar (cahnge) bang / flames [8D]

 

[John Sims]

I thought recirc dump valves were better since the high pressure air in the manifold is diverted back to the low pressure side of the compressor thus accelerating it so it's upto speed

This is subject to what type of air metering system you have. This will work, in theory, with the stand AFM as the "barn door" shuts the end of the induction system. Those with MAF or MAP have an unrestricted induction and the air will just go the wrong way up the induction pipe potentialy slowing air flow.

Guru Racing do an induction pipe that directs the recirc outlet onto the Turbo compressor - I have doubts about this as, subject to where the air flow hits the vanes, it is perhaps as likely to slow the compressor as accelerate it.

I was pretty sick when I installed my Bailey nonrecirc when, a month later, they bought out one with a trumpet so one can realy enjoy the gawooosssssshhhh sound.

As a note, for those that can't differentiate between a bus and a Turbot, a bus will go hiss when stationary.

 

[Fen]

My Turbo has been stationary for over 3 years, if it hissed it would therefore be a bus...

 

[John Sims]

My Turbo has been stationary for over 3 years, if it hissed it would therefore be a bus...

Perhaps. If in any doubt checking the number of seats may help.

It is a sad thing to ponder but, at the moment, a bus is quicker than your Turbo.

 

[eastendr]

No, a puncture [][]

ORIGINAL: Fen

My Turbo has been stationary for over 3 years, if it hissed it would therefore be a bus...

 

[Fen]

I checked; no hissing and only one seat so I think it isn't a bus after all. That it is also slower than a bus would seem to confrm the diagnosis. On the bright side it means no punctures too.

 

[Guest]

So does that mean cheaper tax as well []

 

[Fen]

It's been tax exempt for the last 3 years - can't get much cheaper than that.

 

[Guest]

ORIGINAL: Fen

It's been tax exempt for the last 3 years - can't get much cheaper than that.

I'll set them up, you knock them down []

So whats the ETA on it coming together ?

 

[Fen]

Engine build starts on Friday, bizarrely with a further strip down to remove the head and ladder studs and then a good old-fashioned clean.

I think the book time for a build is 20 hours so hopefully it will be together in a couple of weeks (the builder only works part-time). If it can be in and running by late April I will be (very) happy and busily running it in in time for the dyno day on 7th May. It's tight but do-able so long as nothing much is missing or damaged.

Probably it will be on standard suspension well into May at least but depending how the money is going it will get a KW kit ASAP with ARBs and brakes still TBA. Realistically I doubt it will be on track before June sometime.

 

[Guest]

Sounds like a great project though, and it's coming together (hopefully)