thepest
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| posted on 3/10/08 at 06:04 PM |
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Turbo Charged engines Dump valve
I know there are different types but are any better than others with regard to performance? I am not bothered with having the "Chuff"
noise every time I lift off.
I have a toyota 3S-GTE and it has a recirculating dump valve, if I switched to one that did not recirculate would that give any improvement?
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NS Dev
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| posted on 3/10/08 at 06:25 PM |
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no it would possibly give an un-improvement!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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thepest
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| posted on 3/10/08 at 06:28 PM |
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ok this is rather new to me as I have never had a Turbo engine before. Could you please explain to me why?
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the_fbi
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| posted on 3/10/08 at 07:48 PM |
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A recirc valve will dump air back into the intake system as its already been metered by the MAF/AFM.
A non-recirc type will dump it back to the atmosphere hence the ECU will believe it actually has more air than it has, hence incorrect mixture.
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stevec
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| posted on 3/10/08 at 08:23 PM |
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Mine is atmospheric and works well,
See picture Here
Steve
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MikeRJ
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| posted on 3/10/08 at 08:26 PM |
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quote:
Originally posted by thepest
I have a toyota 3S-GTE and it has a recirculating dump valve, if I switched to one that did not recirculate would that give any improvement?
There would certainly be no performance gain, and if you are running an air flow meter (the older cars using the 3SGTE had them e.g. Rev 2 MR2) then
you will get a hesitation every time you change gear due to the mixture briefly running very rich.
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BenB
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| posted on 3/10/08 at 09:04 PM |
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With a centrifugal type compressor as found in a turbo a recirculating dump valve is a bad thing (unless you've got an up-stream MAP/air flow
sensor). You'll just heat up the air going round and round.
The advantage is lack of noise (a disadvantage to the noisy max power brigade).
The advantage of a recirculating dump valve is mainly in the rootes type (non CR) type compressors. There you save power (a little) but not needing to
suck air through the filter only to dump it to atmospheric. IE with a Rootes type blower a recirculating is a good thing. Otherwise it's usually
a bad thing.... (from a power point of view).
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meany
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| posted on 3/10/08 at 10:19 PM |
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this comes from experience.
replacing a re-circ with a vta type.
1. no power gains to be had.
2. better pickup between gear changes.
3. nice sound for scaring grannies
4. as for overfueling on a maf setup...so miniscule a difference not to worry about.
5. slight pop from the exhaust on the overun..see number 4 
6. can be accused of being a chav 
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blueskate
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| posted on 4/10/08 at 08:53 AM |
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Recirc valve is best on the rev 1/2 3s-GTE . If you're running crazy boost levels then you can justify it i guess! That said i ran an HKS SSQV
on my rev 2 with no detrimental efffects, the ssqv is a different design to most dump valves so doesn't leak like some do. Plus you can turn it
into a recirc if you get annoyed with the noise... oh and you can fit different nossles to make it alter the sound! Just remember to block the hole
where the recirc plumbed into!
Don't get to this point though as you'll be a lot lighter in the wallet 
Semper Paratus!
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thepest
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| posted on 4/10/08 at 12:25 PM |
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Thanks Guys great info. Re-circ dump valve stays for now as I am not after big power or noise.
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Mark G
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| posted on 4/10/08 at 01:07 PM |
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Having seen the picture above, a dump valve wouldn't affect the mixture as the air is recirculated to a part of the induction system before
where it is measured.
I used to have a skyline and I traded the standard recirc valve for a HKS SSQV and DID notice a performance gain. Much quicker to come on boost after
a gear change. Also it spat some pretty mean flames out the exhuast when changing gear on full chat... That said, I don't think you'd
get a fire breather as like I said above the air mass isn't measured untill somewhere later in the system.
[Edited on 4/10/08 by Mark G]
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blueskate
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| posted on 5/10/08 at 01:28 PM |
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that pic is of a 3s-gte with a Map sensor. Rev 1/2 Use an AFM that is located at the airbox. The recirc plumbs into the system just after the AFM.
HTH
Semper Paratus!
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