BOV vacume feed

[hovgaard]

There is a slight spool up time to reach full boost after gearchanges, but far less so than with the original (and heavily surging) setup.

Teigan, when are you coming over?

[Guest teigan]

retaining the heat and consequently the pressure must make your system very efficient. can i buy it at ikea?

i go to norway in the summer every few years. maybe sweden next year if no distractions come up. i'll make it a point to let you know ahead.

[richcamb]

Before this thread gets out of hand, may I suggest that you read up on my dump valve mod in the garage. I realise that the older cars are not setup quite like mine, but I would argue that the same principles apply.

Summing up:

1: You do need a dump valve of some sort, just make sure you don't dump into the atmosphere if you care about engine longevity (unless you put a good airfilter on your valve (in which case it would seem easier to run a pipe to the compressor intake!)).

2: Do you also need a safety valve? I don't know, I haven't got that on any of my cars.

The valve I used cost less than the equivalent of $40 at the local Saab/GM dealer. Contrary to popular belief, it is good for any boost pressure your engine can stand, since, while under boost, the pressure is applied to both sides of its membrane.

Do you need funnier noises or prettier valves? Or does overpriced stuff impress your friends? Can't argue with that.

Cheers!

<{POST_SNAPBACK}>

The main reason for my proposed updates the Esprit are due to the fact that both my Lotus 'dump valve' and wastegate are RUBBISH and are not worth trying to fix. Maybe I dont use my car enough but the wastegate regularly seizes, despite being professionally re-bushed & the diaphragm & valve for the wastegate are almost impossible to obtain.

Unlike the S4 which has electronicly monitored overboost protection, the G cars have to rely on the Lotus dump valve (purge valve really) to get you out of trouble when the wastegate seizes. As this sticks too you end up with a holed piston mid overtake. This is why a safety valve is needed on G cars.

Dont get confused with the Lotus fitted 'Dump Valve' and modern Dump Valves. They are not the same, and work quite differently.

I know I can go out and buy a new Lotus Wastegate and 'Dump Valve', but why would I want to spend the ridiculous sums of money asked for the same poor technology.

I have spent a fraction of the cost on a Tial Wastegate (race proven and parts cheap and readily available), and a GReddy Type S dump valve to keep my turbo spinning (less stress on turbo) coupled with a GReddy relief valve (in place of the Lotus 'dump valve').

I realise that i my dump valve looks very pretty and that it makes a sound, but I dont care about that. What I do care about is that I wont have to stare at the boost gauge and keep my fingers crossed every time I overtake.

Richard

[hovgaard]

If your wastegate is in the habit of sticking and the engine has no other means of overboost protection, then I can certainly see the point of the safety valve. My own cars have knock sensors and what not.

My main point was that the Bosch valve I'm using is cheap and fairly high performing, not to mention safe from an air filtration standpoint. Personally, I don't like to pay more for less.

[richcamb]

Personally, I don't like to pay more for less.

<{POST_SNAPBACK}>

I quite agree. Thats why I'm paying less for more :-) (a lot less!)

[mchlrodrigues]

the one i will so for well already have is the hks ssqv

i feel this will replace the stock one verry well and look almost factory fit

<{POST_SNAPBACK}>

What's its flow capacity of air (mass/unit time)?

[CAM79]

Hi,

I've read the majority of thread (and others!) and now I'm not convinced that adding a atmospheric dump valve is a great idea. I have a Bailey's one fitted to my Escort RS and it does make a noticable difference when it's pushed hard and supposedly it will benefit the life of the turbo.

A while ago I bought a single piston Bailey's dump valve and a fitting kit (silcon t-piece and vacuum hose) for my '84, but I only have ideas on where they should go, have you got a photo's of a setup so I don't screw this up???

Many thanks!

[nicksoldies]

I have a Bailey DV30 fitted. I will post pic's tommorrow. Also info' on fitting, finding the bits etc.

[nicksoldies]

Here are some images of the BOV (Bailet DV30 Recirculating) installed.

I found it neccesary to remove the diffuser tube between the hose and the plenum in order to fit it. A new gasket for that joint would be useful. You may get away with the old one (I did) but you have to be real careful taking the diffuser off to save the gasket. I used a wipe of Blue Hylomar on re assembly to be sure of a good seal (don't want to waste any valuable boost).

The Tee hose had to be shortened to 70mm to fit. You need to cut the same amont off each end (a sharp Stanley knife proved the best tool for this) . I found some Tees had too big a boss where the BOV take off hose joined the main hose to allow enough room for the clips when the hose was shortened. There's not a lot of room to play with. A Forge Motorsport hose was found to be the best in this regard, and a very reasonable price.

The BOV seemed to fit best where I fitted it. I used a recirculating type but piped it down to the road n/s of the gearbox. This ensured there is no oil mist sprayed in the area of the BOV, if any was present in the air trunking. It is silent in operation, no whoosh at all.

I took the vacuum feed from the Black/White hose that feeds the Thermal Ignition Valve ( Green valve in centre of inlet manifold with three hoses - Port 2 is where this pipe goes), it is connected to the front of the front carb', just tee in to it. The vacuum hose is 4mm and a tee can be purchased from any good car spares place.

The only concern I have about fitting a BOV is because some Esprit Turbo's are fitted with a throttle jack, there may not be full vacuum in the manifold to fully open the BOV on throttle close. Above 1600RPM on over run, the jack doesn't allow the throttle butterflies to fully close. I tried disconnecting this and couldn't tell the difference, but as I have a silent BOV, it's hard to tell. Perhaps if someone fits one with a whoosh, they could test to see if there's any difference. That throttle jack also operates when the choke or aircon are operating, so long term disconnection at the jack is not really on, but I have worked out that the overun part bit can be disconnected if neccesary. According to the service notes, it is to stop fuel being stripped off the manifold walls on overun, reducing emmisions, so losing that feature is not critical.

It's worth noting that the original Red hose between the compressor housing and diffuser tube is Nomex based (rated 360 degress if I remember right) whereas the relacement Tees are Silicone (rated 180 degress). I haven't noticed any problem but I haven't driven at really high speed, on full boost. The Silicone hose might not cope under those conditions. Forge said they may make some Nomex Tees later this Year and said they would let me know if they did.

Edited May 21, 2006 by nicksoldies

[CAM79]

Hi Nick,

Many thanks for the info, I really appreciate the help and the photos, it makes things a lot easier, and now I can install it

I was going to attempt it earlier but I sprained my foot last night and realised it really wasn't a good idea! Hopefully I'll be fine for Castle Coombe on Sat!

Again, many thanks!

Brent.

[CAM79]

Hi Guys,

At last I've got around to fitting the dump valve, the setup seems to be a little different to what I have seen in your photos, i.e I don't seem to have any suitable vacuum feed to tie in the t-piece. Looking in the manual and also have consulting a local Lotus dealer I was advised just to tap into the boost gauge line (A on the photo below). On starting the car I don't seem to get any vacuum/air out of the t-piece although the boost gauge still seems to function correctly, on taking it for a quick spin, nothing I am doing something wrong here?

Cheers,

Brent.

Edited August 25, 2007 by CAM79