BOV vacume feed

[Splashout]

I have thought about fitting a BOV a number of times but never completed the thoughts due to not really knowing where you would take a vacume feed from for the BOV?

Any ideas guys?

[richcamb]

How about the inlet manifold vacuum take off points near the rear carb?

Thats what I am planning on doing once my beastie is up and running.

They are used with a vacuum rail on the early Turbos, but later ones just use the ports near the front carb, and blank off the rear pair with grub screws.

Edited August 23, 2005 by richcamb

[Jussi]

Here's previous discussion:

http://www.glcforum.com/ukesprit/forums/in...wtopic=1026&hl=

And here is Greddy type S installation on Giugiaro:

http://invenair.com/

[Splashout]

How about the inlet manifold vacuum take off points near the rear carb?

Thats what I am planning on doing once my beastie is up and running.

They are used with a vacuum rail on the early Turbos, but later ones just use the ports near the front carb, and blank off the rear pair with grub screws.

<{POST_SNAPBACK}>

sounds like an option has it been done any pics?

Here's previous discussion:

http://www.glcforum.com/ukesprit/forums/in...wtopic=1026&hl=

And here is Greddy type S installation on Giugiaro:

http://invenair.com/

<{POST_SNAPBACK}>

Jussi there didnt seem to be any definative answer in that disscussion hence this post

[Evil_Dr_Fish]

I have to confess I haven't read this yet! (I'm relying on the title )

Is this of any use Glyn?!

http://esprit.driestone.com/index.php/Esprit/InstallingABOV

[richcamb]

sounds like an option has it been done any pics?

Glyn

I think someone on the list had added a BOV to a carbed Turbo.

Not sure what method they used.

Dermot will know who it is.

The idea of using the inlet manifold ports is just something I thought of whilst planning my own installation. With the carb butterflies closed between gearchanges, there should be a whole lot of useful vacuum for operating the BOV. Well thats the theory in any case. Never set up a BOV so not sure on the finer points.

I am planning on fitting my BOV using a 'T' piece to replace the rubber connecting pipe between Turbo and Diffuser. It all sounds quite straightforward which bothers me as I havent seen it done before.

[Evil_Dr_Fish]

AJay has done a LOT to a carbed turbo... He may have a good idea too?

http://www.glcforum.com/ukesprit/forums/in...&CODE=12&CID=69

Be nice if you PM him to ask tho... his car went squelch on sunday

[Splashout]

AJay has done a LOT to a carbed turbo... He may have a good idea too?

http://www.glcforum.com/ukesprit/forums/in...&CODE=12&CID=69

Be nice if you PM him to ask tho... his car went squelch on sunday

<{POST_SNAPBACK}>

From what i can see Ajays car still has the standard bov (or fart valve) I have read the other link before and there isnt any info there.

The only instal i have ever seen (might be on EFF not sure) they drilled and tapped into the carb itself which seems a little drastic.

Supprised no one has done it.

[Evil_Dr_Fish]

He seems to really know his G-Cars tho - he may be able to help?

<pokes Andy with a PM>

[AJay]

Yes Glyn you are right i only have the standard Dump valve on the engine.

I have driven cars with BOV's and the Whoosh at slow speeds is annoying (to me) at low revs and sounds like the no 10 buss coming down the road.

I am running 10 Psi boost and the standard lotus Dump valve works perfectly.

At low to medium throttle the over boost situation is controlled and there is no whooosh, however when really going for it the whoooosh is present for a very short period between gear changes.

Now its only an opinion but the LOTUS dump valve releases just enough pressure to take the over boost pressure off the turbine blades and shuts again when pressure equalises to the set boost thus reducing the shock loading on the blades by keeping them under a relatively constant pressure. As throttle is opened then boost is already in the plenum thus no lag.

Now a BOV releases ALL the pressure to atmosphere thus unloading the compressor blades. the stored inertia in the blades must then speed up the rotor to above or close to it the designed maximum rpm. when the throttle is opened the BOV shuts thus applying full boost back to the turbine blades Result high shock loading on the blades. I have seen turbine shafts snap with BOVs Fitted.

I know my argument has faults, but, under such light boost as 10 PSI i am pretty sure that the arguments are academic. It all comes down to whooosh or not to whooosh.

I would take the vacuum feed off the grub screw in the rear Carb manifold if i was fitting one.

[Splashout]

hmmm interesting

when driving mine hard i do get a whosh on most gear changes and admit that i quite like it and one reason i have considered fitting it (lends back to my jap days lol) as for the shock where does this come from as the impeller is constantly driven by the exaust but with the valve open obviously does not produce any pressure and once valve shut would build pressure again gradually.

[Evil_Dr_Fish]

My dump valve is sufficiently loud on high rev / high boost / hard driving gear changes that my (slightly rahuude bwoy) friend asked me if I had a bov fitted anyway!

[richcamb]

And here is Greddy type S installation on Giugiaro:

http://invenair.com/

<{POST_SNAPBACK}>

[Evil_Dr_Fish]

They're still freely available on ebay

I don't know how this price compares with other BOV's (don't forget he wants

[Splashout]

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

[richcamb]

They're still freely available on ebay

I don't know how this price compares with other BOV's (don't forget he wants

[AJay]

hmmm interesting

when driving mine hard i do get a whosh on most gear changes and admit that i quite like it and one reason i have considered fitting it (lends back to my jap days lol) as for the shock where does this come from as the impeller is constantly driven by the exaust but with the valve open obviously does not produce any pressure and once valve shut would build pressure again gradually.

<{POST_SNAPBACK}>

Good point, as i said only an opinion and i have seen turbine shafts snap with BOV's fitted (could be coincidence).

But if the pressure takes time to build again as you suggest then this would cause lag when throttle pinned again!! would it not.

I am probably wrong, as it is not the conventional view. may be i need to read more and stop driving the car.

Edited August 25, 2005 by AJay

[Splashout]

may be i need to read more and stop driving the car.

<{POST_SNAPBACK}>

Go and wash your mouth out

dont let me hear you talk that way agaion

Guess i will have to fit it i plan to do it in a reversable way so if i dont like it can just take it off again!!

[Evil_Dr_Fish]

What stock one?

Are you confusing your dump (pop off) valve with your Blow off Valve? ...Cos they're not the same and you need both! (well, kinda!)

[Splashout]

What stock one?

Are you confusing your dump (pop off) valve with your Blow off Valve? ...Cos they're not the same and you need both! (well, kinda!)

<{POST_SNAPBACK}>

Dont think so robin i am refering to the dump valve assembly as described in the parts list. The silver bit that is attached to your plenum and has the fuel pressure regulator attached to it. I believe this is a dump valve

Do they have a pop off valve? I didnt think they did as if they did you would not get overboosting as this would pop and vent the pressure when it reached its set value??

[richcamb]

Do they have a pop off valve? I didnt think they did as if they did you would not get overboosting as this would pop and vent the pressure when it reached its set value??

<{POST_SNAPBACK}>

I was led to believe that if it ever worked properly then it should also do just this.

Definitive answer required from Lotus I think.

Its a very crude design, and I know my one sticks shut/sticks open.

Was looking at mine a few weeks back and I pressed the piston open a bit.

Took a week and some easing oil for it to pop back!!!!!

Its just gotta go!

I dont really like systems where pressurized air has to 'force' its own way out through a 'dump valve'. The audible flutter between gearchanges indicates just how much the turbine has slowed down. I used to like that sound until I realised what was actually happening. Now it makes me cringe.

I would much rather have a system where the 'door is opened' for the air to escape and with the turbine still spining fast it shouldnt take long for the pressure to build again when the valve shuts.

[Evil_Dr_Fish]

Yep! Glyn, It's pop off

( I think! - I'm not about to get itno exactly which expression means which - I know there are three expressions and two actual devices!)

What the Esprit *HAS* is what you mention there - it's *supposed* to protect the engine from sticky wastegate induced overboost.

As Rich says, they're more often than not stuck fast. (hence >>Bang!<< )

The BOV you want to fit is to release pressure after lift off.

Since it seldom works anyway I suppose you possibly COULD replace it with a BOV?

HTH

Robin

[Splashout]

aghhh bugger more confused now than when i started lol anyway it didnt help when my waste gate stuck so gone change it can always fit a decent pop off valve somwhere else if desire takes me lol

[richcamb]

Oh...I dont know what to do now.

I do like the Greddy install on the http://invenair.com/ site but just realised by fitting this I would have no overboost protection (not that I did anyway with the Lotus contraption), and replacement wastegates that are more reliable are mucho money

Too much to think about.....giving me a headache

Edited August 26, 2005 by richcamb

[Evil_Dr_Fish]

Boost controllers like the Greddy one I am having fitted have an overboost warning.

Mine will be set at 0.8 bar and will go red and bleep like an Eddie Murphy performance on children's TV.

Gives you a chance to slow down before the bang clatter clatter!