Dump or Diverter valve?

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Dump or Diverter valve?

Postby Hector2021 » Sat 17.09.2022, 09:20

P. O for some reason known only to him had fitted a dump valve. For obvious reasons it sounds awful and is frankly embarrassing. I fully intend to remove it at the earliest opportunity.
My question is, do i need to replace it with a diverter valve, or did the car not have one from factory?
Id be chuffed if it didnt need one since annoyingly i gave a very expensive one away a couple of years ago.
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Re: Dump or Diverter valve?

Postby Fredjohn » Sat 17.09.2022, 09:36

AFAIK just replace it with a new induction hose as the existing one will have a feed to the dump valve. You will also need to block off the vacuum feed.

Alternatively do what I did and wrap some foam around the dump valve exit holes. Instantly quiet and no boy racer whooshes! I used foam from a small Honda motor mower intake filter.

Some dump valves dump into the air intake box rather than the atmosphere, so are somewhat quieter. What make/type is yours?
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Re: Dump or Diverter valve?

Postby Hector2021 » Sun 18.09.2022, 10:20

I actually just tried it with the vacuum hose disconnected and blocked off with a bolt. I dont think that it drove as spiritedly and seemed to lack power or boost. The boost gauge was reading around 0.5 at high revs. It also 'chattered' on backing off the throttle where with the vacuum attached it did the characteristic Whoosh sound.
I put the vacuum hose back on and the performance came back. I really want it gone as i so dislike the sound and stereotype image, but i need to know whether it needs to be replaced by something else (e.g a Diverter).
In the meantime i will try the sound deadening approach with a foam jacket, or something similar.
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Re: Dump or Diverter valve?

Postby Jamie N » Sun 18.09.2022, 10:25

Never mind the dump valve Hector, get the pictures of your new car posted!. ;-)
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Re: Dump or Diverter valve?

Postby Hector2021 » Sun 18.09.2022, 10:30

Ha ha, Im trying but when i add an image via the add attachment option, i just get a message telling me the file is empty. I dont think admin have allowed me image posting rights?
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Re: Dump or Diverter valve?

Postby Fredjohn » Sun 18.09.2022, 10:36

To be honest I don't know what a diverter is. But if you look at the parts catalogue, you will see there is just an induction pipe between the plenum and intercooler, no diverter.

The dump valve will not work without the vacuum pipe connected. That's why it sounded weird. If you don't like it , remove completely and fit a new induction pipe to replace the one the dump valve was tee'd from. Or just add a straight metal pipe to replace the T pipe.

A photo of existing installation (and car!) would help.
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Re: Dump or Diverter valve?

Postby Jamie N » Sun 18.09.2022, 10:39

Hector2021 wrote:Ha ha, Im trying but when i add an image via the add attachment option, i just get a message telling me the file is empty. I dont think admin have allowed me image posting rights?


Create an account and Upload your pictures to this.... http://imgur.com/ , on the picture you want to uploadclick 'BBCode' and select size as 'large thumbnail', add the code to your post, job done.

You can't upload pics directly from your machine BTW.
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Re: Dump or Diverter valve?

Postby dapinky » Sun 18.09.2022, 10:49

Hector2021 wrote: I dont think admin have allowed me image posting rights?


It isn't that - but the forum software is broken, and I've sent messages to the man who can (hopefully) fix it, so we're in a waiting game......

..... Oh, and a Diverter valve was never an option from Lotus, but can be easily fitted in place of an existing (already fitted) open-loop blow-off valve.

Lotus decided that the turbo size and performance didn't need one to be fitted (although technology moves on, and many of us have now fitted them). I use a Forge 008 which can be either open or closed loop (depending if you fit a return pipe or not). It isn't particularly loud like some on the market, and a simple silicone hose elbow sends the overboost into the inlet filter housing to remove the noise altogether.
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Re: Dump or Diverter valve?

Postby Hector2021 » Sun 18.09.2022, 11:00

dapinky wrote:
Hector2021 wrote: I dont think admin have allowed me image posting rights?


It isn't that - but the forum software is broken, and I've sent messages to the man who can (hopefully) fix it, so we're in a waiting game......

..... Oh, and a Diverter valve was never an option from Lotus, but can be easily fitted in place of an existing (already fitted) open-loop blow-off valve.

Lotus decided that the turbo size and performance didn't need one to be fitted (although technology moves on, and many of us have now fitted them). I use a Forge 008 which can be either open or closed loop (depending if you fit a return pipe or not). It isn't particularly loud like some on the market, and a simple silicone hose elbow sends the overboost into the inlet filter housing to remove the noise altogether.


Ok, that explains the issue over the images i guess, and also the question of whether a relief valve of either kind is required. i will probably just measure the diameter of straight pipe needed to replace the aluminium T-piece added connected to the valve. Almost certainly cheaper than a complete new hose.
I'll add a picture of the current set up too once the attachment issue is sorted. Frustratingly i gave away a Forge Diverter that i took off my TT a few years ago. I seem to remember if costing me north of £100 at the time.
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Re: Dump or Diverter valve?

Postby Jamie N » Sun 18.09.2022, 11:08

Test pic straight from Imgur ...
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Re: Dump or Diverter valve?

Postby RonR » Sun 18.09.2022, 12:06

Mine also had a dump valve (HKS?) fitted when I got it, the PO loved it but I removed it as soon as I could. Luckily the original induction pipe was in the box of spares I got with the car along with the original blanking cover for the vacuum take-off on the back of the throttle housing. It took about an hour to put things back the way they should have been, and that included looking things up on this site and in the manual.

Recently I came across the old dump valve and noticed there's a recess in the casting so a vent pipe can be fitted. I'm contemplating putting it back on the car but this time fitting an outlet hose venting into the air box.

It may be worth checking your dump valve to see if you could fit a similar vent pipe.
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Re: Dump or Diverter valve?

Postby Hector2021 » Mon 19.09.2022, 19:56

Unfortunately i seem to be unable to sign up to Imgur as it tells me my region is not supported. I tried to add images via an alternative web based image sharing site but the links dont seem to work. Guess i'll have to wait until the site is fixed before i can post any images
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Re: Dump or Diverter valve?

Postby HJ2 » Tue 20.09.2022, 08:05

Can’t you use a vpn when you sign up!
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Re: Dump or Diverter valve?

Postby dunnlor » Tue 20.09.2022, 19:00

I drilled a hole (maybe 1") into the plastic air filter canister and attached a hose fitting. The dump valve connects to it.
It's nearly silent.

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Re: Dump or Diverter valve?

Postby Hector2021 » Wed 21.09.2022, 16:03

dunnlor wrote:I drilled a hole (maybe 1") into the plastic air filter canister and attached a hose fitting. The dump valve connects to it.
It's nearly silent.

Tom

This would be a good solution but for two minor problems i have:
1. the Dump valve does not have a facility to vent from it through a piped connection. The outlets are four slots around the outside edge of the valve
2. i dont have a standard air box. Again the P.O swapped it out for a 'performance' K&N type filter.

I would sooner have an original set up and i can get back to halfway there once the straight pipe section i ordered arrives to replace the T-section. Finding an original air box might be a bit of a challenge, or at leasr an expensive one.
Thankfully these seem to be the only two drifts from a standard set up that the P.O has done. Everything else about the car looks bob on, servicewise and maintenance wise. Underneath is lovely clean dinitrol and it has had now advisories on any recorded MOT's apart from this years failure in May due to a worn CV boot.
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Re: Dump or Diverter valve?

Postby dapinky » Wed 21.09.2022, 16:23

Whilst they are not exactly plentiful in scrap yards these days, be aware that the air filter and it's 'box' are sourced from an Austin Maestro 2.0 should you need to try and find one.
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Re: Dump or Diverter valve?

Postby Hector2021 » Wed 21.09.2022, 20:42

Dave,
Thats really interesting. I thought these cars were a GM parts bin special. I wouldnt have expected BL or Austin Rover parts too.
May well be worth calling a few breakers yards... Although i may be a few years late.
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Re: Dump or Diverter valve?

Postby Hector2021 » Wed 28.09.2022, 16:28

just tried posting an image via a hosting site..... It didnt work!
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Re: Dump or Diverter valve?

Postby rip » Fri 30.09.2022, 11:47

Hector2021 wrote:Dave,
Thats really interesting. I thought these cars were a GM parts bin special. I wouldnt have expected BL or Austin Rover parts too.
May well be worth calling a few breakers yards... Although i may be a few years late.


Not entirely all GM. I believe some of the air vents were taken from a Ford Transit.
I was told the following from a Lotus specialist mechanic:
Lotus does suspension development work for many companies (which most of us know). They often take obsolete parts in part payment for this work then use these parts on their own cars.

As for the dump valve itself, as Dapinky mentioned, the cars were not built with one. Many of us have fitted them because there is a school of thought that when the throttle is closed, this creates pressure in the induction side, which opposes the spinning of the turbo (causes it to stall). This not only causes stress on the turbo bearings but when we change up a gear & accelerate again, we want the turbo already spinning so it can provide boost as quickly as possible.
The whoosh sound is a matter of taste. The valve can be plumbed into the air filter, but this is not necessary. My Greddy had 2 attachments, a 'trumpet' & a hose attachment. The 'trumpet' one was obviously there to make it noisy. I found the whoosh sound fun for a few minutes but it soon became annoying.
There is also a school of thought which argues that you should not feed the air intake with warm air; it should be as cool as possible.
When I fitted the hose attachment, I directed it down into the engine bay & stuck a small air filter on the end. No recirculating warm air & no annoying whoosh.
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Re: Dump or Diverter valve?

Postby par » Fri 30.09.2022, 14:40

My car appears to have developed a loud chirp/squeak only when making swift progress, it seems to only occur at the top end of the rev range when foot is lifted off the accelerator and the clutch is dipped to grab the next gear. I dont do this very often but it does seem consistent.

I wonder if this is the standard system (the wastegate has been ported) struggling to cope with getting rid of all the pressure when the demand stops suddenly and would a dump valve help with this?

Any thoughts?
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