BOVs, chips and all sorts of things

[madmike]

OK, I'm about ready to do MY first mod on my car.

I want to add a blow off valve. I've read the review on www.lotusespritworld, and on Marcus Esprit World http://freudhoefer.de/lotus/esprit/

My question: Are there any other recommendations from you folks on a good BOV. Keep in mind I'm in the US and my ability (skill level) to work on cars is limited...I'm choosing this as my first mod because of the purported ease of install, and because it really needs one.

Also, I have read all the chip reviews on Kato's site. As the listers here have kindly pointed out, I have the S4s Mark V chip. Apparently the one that still has the 3K hiccup. Could someone please describe what this issue actually is? And how does the improved code improve the drive?

One last question on the chips, If I were to upgrade my chip, I also have the high torque, 310 and 330 HP variants to choose from. I have a TEC T3/T4 hybrid turbo with all the other required goodies (Sport 300 fuel pump, Freeflow exhaust, will have a BOV by then, K&N filter, etc.) The high torque seems very safe...what of the 310 and 330 variants? Will increasing boost to 1.1 or 1.2 bar decrease the engine safety, or significantly increase the wear and tear on the engine? I'm just wondering if installing those chips will put me too close to the edge reliability-wise...

Look forward to hearing your opinions.

Mike

[mikeylad]

is a 'blow off valve' an American Dump Valve, or slang for something i shouldn't know about at my early stage in life???

[madmike]

Blow off valve, dump valve, same thing. Most refer to it as a BOV, so I've noticed.

[Gary-SPG-Moore]

many state the BOV blows the air into the atmosphere

while a dump valve dumps the air back into the IC piping/motor. Some also call these hooter valves

on a side note, the HKS BOV is NOT designed to run over 18 PSI of boost.

[lotusguy]

mikeylad said: is a 'blow off valve' an American Dump Valve, or slang for something i shouldn't know about at my early stage in life???

Hi all,

Seems a little further clarification is in order. A Blow-Off Valve (BOV) and a Dump Valve (used on Lotus Carb Turbos) are different animals.

A Dump Valve is a basic pressure relief Valve and is sometimes called a Pop-Off Valve. Have you ever seen or used a household pressure cooker. That little device on top of the lid that vents steam pressure to keep the pot roast from being Blown all over the ceiling is, in essence, a Dump Valve.

A boost Dump Valve monitors the pressure within the plenum upstream from the throttle plates and vents when the boost pressure reaches a pre-set limit.
It is not a smart Valve, it's oblivious to throttle position, intake manifold pressure/vacuum or turbo rpm. The Dump Valve "single mindedly" monitors plenum pressure and vents excess pressure without consideration for other factors. When the plenum pressure drops below the preset limit, the Valve closes again.

The Dump Valve will vent during full throttle conditions anytime the boost pressure exceeds the preset limit for whatever reason. It will also vent
when the throttle is closed abruptly during a boost condition. When the throttle closes the turbo output suddenly has no where to go, and the plenum pressure spikes. The Dump Valve will open if/when the spike exceeds the preset limit, govern by the spring in the Valve, and close again when the pressure drops and is overcome by the spring pressure again.

The Dump Valve opens a large orifice sized to quicly vent excess pressure. But when it closes again, the turbo is still spinning and quickly pressurizes the plenum back above the preset limit, so the Dump Valve opens again at least partially. The cycle repeats until the turbo slows to the point at which it can no longer pressurize the plenum beyond the limit. The cycle occurs rapidly and seems more like a "flutter". The fluttering vent cycle is what produces the characteristic "Horse Whinney".

A Blow Off Valve is similar to a Dump Valve, but adds an external control circuit and vents the plenum in response to throttle position. A Throttle Position Switch (TPS) could be used to actuate the BOV, but on older carburetted, non-ECU engines, the BOV typically monitors manifold vacuum downstream from the throttle plates since closed throttle = high manifold
vacuum. A vacuum port is located in the side of the intake manifold where it will be 1) immediately downstream from the throttle plates when they are
fully closed and 2) upstream from the plates as soon as they are cracked open. A vacuum line runs from that port to a diaphragm in the BOV.

When the throttle is closed, the port applies high vacuum to the BOV diaphragm to open the Valve and vent plenum pressure. When the throttle is cracked open, the throttle exposes the port to plenum pressure, killing the vacuum at the diaphragm and closing the Valve. Hence, the BOV operates in response to throttle position, venting the plenum when the throttle is closed. It remains open/ venting as long as the throttle remains closed. Typically the BOV does not cycle or flutter, so the usual sound is one smooth whistle... no flutter.

If the throttle is slammed shut when the turbo is fully spooled up and at full boost, the sudden high back pressure condition can physically damage
the compressor wheel, and will definitely cause the turbo to rapidly slow down. Then when the throttle is opened again, the turbo will have to accelerate again before achieving full boost. The result is "turbo lag".
The BOV vents the plenum back pressure, allowing the turbo to keep spinning at high rpm, and preventing the damaging pressure surge.

The Dump Valve is a pressure relief / over-boost protection device, whereas the BOV is a throttle-sensitive plenum vent.

The waste gate is quite different in that it does not vent plenum pressure. It vents exhaust gasses, by-passing the turbine wheel in order to control
the amount of boost produced in the first place. Dump and Blow-Off Valves limit boost "after" it's delivered to the plenum.

The wastegate and Dump Valve both monitor "plenum pressure" and act to control and limit available boost levels. The Blow-Off Valve monitors "throttle position" (manifold pressure) and vents the plenum to kill any boost present at times when boost is not wanted (closed throttle). Hope this better explains the two. Happy Motoring!...Jim '85TE

[madmike]

Thanks Jim, I feel a bit more educated about these sorts of things, which is what I'm geneally trying to do re: my Esprit.

What I want is a BOV. Any recomendations on which one to get? Also, the above chip questions still beg for some opinions...

[ErnestM]

mikeylad said: is a 'blow off valve' an American Dump Valve, or slang for something i shouldn't know about at my early stage in life???

ErnestM

[karlfranz]

In my neck of the woods a BOV is referred to as a "sneeze valve".

[silver12r]

Buy your BOV from Sanj (grungex on this board). I got mine from him and it was a cakewalk install and it looks absolutely killer. It also sounds better than advertised....

[Skerd]

This months Sport Compact Car issue has a full article on BOV's DV's, and related items. Everybody brags about BOV's being the greatest thing, but I had mine installed in October, and nobody can get it to work yet! Go for the 330hp chip, but make sure you send them your blue memcal cartridge thing and let them do the swap. It is impossible to do yourself. Even Lotus headquarters in Georgia would not do it.

[Squelch]

Instead of shipping them you mem-cal why not just pick up a spare blank one ? then you could have the stock mem-cal and one with the other code...

check:
www.wcengineering.com

[MikeyRide]

Apparently the one that still has the 3K hiccup. Could someone please describe what this issue actually is? And how does the improved code improve the drive?

If you have to ask, I'd say don't worry about it. My car sometimes felt like it had shut down for an instant while accelerating through 2800rpm on part throttle in 1st gear. VERY annoying. With Andy's updated code, it behaves properly.

[sanj]

lotusguy said:

mikeylad said: is a 'blow off valve' an American Dump Valve, or slang for something i shouldn't know about at my early stage in life???

Hi all,

Seems a little further clarification is in order. A Blow-Off Valve (BOV) and a Dump Valve (used on Lotus Carb Turbos) are different animals.

Hi Jim,

I think it's more a case of what version of the English language you're using. What we in the US call a BOV is indeed referred to as a Dump Valve in the UK, whether it vents to atmosphere or returns to the airstream. The BOV kits that I sell have valves that are indeed referred to as Dump Valves by their manufacturer, and so are the valves sold by their competitors. Yet there is no arguing that these kits are *not* dump valves by your definition...

Cheers,
Sanj

[lotusguy]

sanj said:

lotusguy said:

mikeylad said: is a 'blow off valve' an American Dump Valve, or slang for something i shouldn't know about at my early stage in life???

Hi all,

Seems a little further clarification is in order. A Blow-Off Valve (BOV) and a Dump Valve (used on Lotus Carb Turbos) are different animals.

Hi Jim,

I think it's more a case of what version of the English language you're using. What we in the US call a BOV is indeed referred to as a Dump Valve in the UK, whether it vents to atmosphere or returns to the airstream. The BOV kits that I sell have valves that are indeed referred to as Dump Valves by their manufacturer, and so are the valves sold by their competitors. Yet there is no arguing that these kits are *not* dump valves by your definition...

Cheers,
Sanj

Sanj,

I agree that there are differences in the labeling of things, especially mechanical things, between the 'Pond'.

There doesn't seem to be a standard definition for what are clearly two distinct things with completely different functions and objectives.

Lotus refers to the plenum pressure relief valve as a 'Dump Valve', but this is a 'Dumb Valve' such as in my descrption and is oblivious to throttle position. While the valve you sell is controlled by thottle position or at least the vacuum consequence of throttle position.

Because many carb'd car owners inquire about whether they already have one as stock, I felt it appropriate to differentiate between the two as the BOV you sell can (with some modification) be installed on the earlier carb'd cars for some additional benefit.

So, whatever label you affix to them, it's important to know and understand the differences between them. Happy Motoring! Jim'85TE

[Skerd]

Squelch said: Instead of shipping them you mem-cal why not just pick up a spare blank one ? then you could have the stock mem-cal and one with the other code...

check:
www.wcengineering.com

The problem is the one there now is soldered in place. You cannot just snap a new one in, you have to remove the original one first. Nobody, and I mean NOBODY, will remove a soldered chip from a circuit board, and then solder a new one in. Eventually, Sanj did it for me with a one day turnaround time. Go to him in the first place!

[Squelch]

Skerd said:

The problem is the one there now is soldered in place. You cannot just snap a new one in, you have to remove the original one first. Nobody, and I mean NOBODY, will remove a soldered chip from a circuit board, and then solder a new one in. Eventually, Sanj did it for me with a one day turnaround time. Go to him in the first place!

Excuse my ignorance, but if you DON'T remove the chip, then why would you replace the chip... I was suggesting that you get an entire replacement mem-cal, then you NEVER have to do any removal or replacemnt of a chip, just the entire mem-cal carrier... much simpler, much safer.

[Skerd]

Squelch said:

Excuse my ignorance, but if you DON'T remove the chip, then why would you replace the chip... I was suggesting that you get an entire replacement mem-cal, then you NEVER have to do any removal or replacemnt of a chip, just the entire mem-cal carrier... much simpler, much safer.

When you get your second replacememt mem-cal, how would you remove the stock chip that is already soldered in place? The chip is one small part of the blue mem-cal cartridge.

[cnh1990]

Actually I think from what I remember at LOG, John Welch's chips comes with the mem cal cartridge and all that is required is to snap the old one out and the new one in.
Calvin 90 SE

[Skerd]

cnh1990 said: Actually I think from what I remember at LOG, John Welch's chips comes with the mem cal cartridge and all that is required is to snap the old one out and the new one in.
Calvin 90 SE

That would explain the confusion.