Lotus Turbo Esprit Fact Respository for the 1981-1987 Lotus Turbo Esprit (the Giugiaro cars.)

Custom Lotus parts, guides and facts for the Lotus Turbo Esprit. 2.2 Liter Lotus engine with turbo. Guides for tires, wheels, engine, transmission as well as custom carbon fiber, aluminum and fiberglass parts for the Lotus Turbo Esprit. As well as an adjustable suspension for the front of the car.

Facts for both the US and UK Lotus Turbo Esprit, including spring rates, engine info, parts, modifications, specifications (specs), pictures, users, owners and vital information for the Lotus.

Some information might be valid for non turbo cars and other Esprits as well, some custom parts may be usable on non turbo version of the car and other parts may work on the later Esprits. And suspension adjustment and springs, coilovers coil overs and other stuff.

Turbo Esprits have the 2.2 liter lotus engine and 210 horsepower, we have custom fiberglass, aluminum and carbon fiber parts being developed along with a multitude of facts on the lotus cars.

We will have replacement OEM parts as well as custom unique parts for the esprits made from fiberglass, carbon fiber and aluminum.

We are interested in hearing from other lotus owners including S1 owners, S2 esprit owners and S3 n/a lotuses. We have a variety of owners.

Website designed by: DrieStone Design


InstallingABOV

Esprit.InstallingABOV History

Hide minor edits - Show changes to markup

June 10, 2005, at 11:50 AM by 69.177.168.84
Deleted lines 0-1:
Author's Note: This is theoretical, and although I will test this in the near future the actual performance increase is unknown. I do doubt a number of the BOV installs that other carbureted Esprit owners have installed.

Changed line 11 from:

to:

Deleted lines 16-31:

The problem

An optimal set up would allow the blow off valve to open with as little pressure as possible. To accomplish this, we need to equalize the pressure inside the blow off valve under boost and decrease the pressure on the back of the diaphragm only when we close the throttle body. Usually this would be done by running a vacuum line from behind the throttle body to the BOV. This way when the throttle closes, this line would see vacuum and not only would the excess boost on one side push the diaphragm open, the vacuum would help the process. Of course even with this setup there are pressure losses, and the two sides aren't 100% equal (under boost), but close enough that we don't need to install a spring as heavy as what would be required on a dump valve (so a car running 8psi boost only needs a spring set to maybe 5psi not 12psi.)

On an EFI car there is a single butterfly and running a vacuum line from behind it is easy. On a carbureted engine we have four butterflies, and the air and fuel have already been mixed after the butterflies.

There are two options (at least) to plumb a BOV. The first is to use this mixed air to provide vacuum under throttle lift, the second is to control the BOV electronically. The issue with using the air/fuel mixture is that fuel can degrade the internals of some Blow Off Valves.

Building an Electronic Controller

By running a second vacuum line from our turbo to the back side of the BOV (equalizing the pressure inside the BOV,) and installing an electric solenoid that vents this second line to atmosphere (or vacuum)


The low-tech approach is to control the solenoid with a throttle switch that energizes when the throttle is closed. AutoSpeed magazine has two articles that you need to read if you're interested in getting hightech. The first is The $70 Electronic Blow-Off Valve the second is The All-Electronic Blow-Off Valve.

Changed lines 27-29 from:
By plumbing your BOV vent back into your intake you can come closer to equal pressure on both sides of the compressor.

If you can find a 3 way vacuum solenoid you can run one barb to the vacuum pump (maybe) and the other barb to boost. This way the BOV actually would see vacuum on the back side when you switch the solenoid.
to:
By plumbing your BOV vent back into your intake you can come closer to equal pressure on both sides of the compressor.
August 19, 2004, at 08:29 AM by 65.75.16.52
Changed line 33 from:
The low-tech approach is to control the solenoid with a throttle switch that energizes when the throttle is closed. AutoSpeed? magazine has two articles that you need to read if you're interested in getting hightech. The first is The $70 Electronic Blow-Off Valve the second is The All-Electronic Blow-Off Valve.
to:
The low-tech approach is to control the solenoid with a throttle switch that energizes when the throttle is closed. AutoSpeed magazine has two articles that you need to read if you're interested in getting hightech. The first is The $70 Electronic Blow-Off Valve the second is The All-Electronic Blow-Off Valve.
August 19, 2004, at 08:27 AM by 65.75.16.52
Changed line 23 from:
On an EFI car there is a single butterfly and running a vacuum line from behind it is easy. On a carbureted engine we're not so lucky (not only do we have four butterflies, the pressure after the butterfly is also an air/fuel mixture.)
to:
On an EFI car there is a single butterfly and running a vacuum line from behind it is easy. On a carbureted engine we have four butterflies, and the air and fuel have already been mixed after the butterflies.
Changed lines 25-29 from:
Although someone could engineer a solution to read the pressure after the butterflies, it would be cost prohibitive. The easy solution is to run a second vacuum line from our turbo to the back side of the BOV (equalizing the pressure inside the BOV,) and installing a solenoid that vents this second line to atmosphere at 0 throttle (thereby creating our pressure differential.)
to:
There are two options (at least) to plumb a BOV. The first is to use this mixed air to provide vacuum under throttle lift, the second is to control the BOV electronically. The issue with using the air/fuel mixture is that fuel can degrade the internals of some Blow Off Valves.

Building an Electronic Controller

By running a second vacuum line from our turbo to the back side of the BOV (equalizing the pressure inside the BOV,) and installing an electric solenoid that vents this second line to atmosphere (or vacuum)
Added lines 33-34:
The low-tech approach is to control the solenoid with a throttle switch that energizes when the throttle is closed. AutoSpeed? magazine has two articles that you need to read if you're interested in getting hightech. The first is The $70 Electronic Blow-Off Valve the second is The All-Electronic Blow-Off Valve.

Deleted lines 40-49:

Parts

You can actually set this system up for less than $100, although I would purchase an adjustable BOV which means we're closer to $200-$250.

Search eBay for a DSM Boost Control Solenoid (DSM is Diamond Star Motors, the 00-99 Eclipse, Talon Laser.) You should be able to grab this for $10 shipped.

Also on eBay, or elsewhere you can find a 1G DSM BOV (new is $80, used is less.)

Radio Shack should have the switch.

Changed lines 47-51 from:
If you can find a 3 way vacuum solenoid you can run one barb to the vacuum pump (maybe) and the other barb to boost. This way the BOV actually would see vacuum on the back side when you switch the solenoid.

Alternative idea

You could build a mechanical BOV of sorts with another throttle body. It could either be activated by cable or with some kind of vacuum actuator (like on the HVAC controls.) The benefits (if tuned properly) could outweigh a traditional BOV.
to:
If you can find a 3 way vacuum solenoid you can run one barb to the vacuum pump (maybe) and the other barb to boost. This way the BOV actually would see vacuum on the back side when you switch the solenoid.
April 01, 2004, at 05:55 PM by JS
Changed line 23 from:
On an EFI car there is a single butterfly and running a vacuum from behind it is easy. On a carbureted engine we're not so lucky (not only do we have four butterflies, the pressure after the butterfly is also an air/fuel mixture.)
to:
On an EFI car there is a single butterfly and running a vacuum line from behind it is easy. On a carbureted engine we're not so lucky (not only do we have four butterflies, the pressure after the butterfly is also an air/fuel mixture.)
April 01, 2004, at 05:54 PM by JS
Changed line 21 from:
An optimal set up would allow the blow off valve to open with as little pressure as possible. To accomplish this, we need to equalize the pressure inside the blow off valve under boost and decrease the pressure on the back of the diaphragm only when we close the throttle body. Usually this would be done by running a vacuum line from behind the throttle body to the BOV. This way when the throttle closes, this line would see vacuum and not only would the excess boost on one side push the diaphragm open, the vacuum would help the process. Of course even with this setup there are pressure losses, and the two sides aren't 100% equal, but close enough that we don't need to install a spring as heavy as what would be required on a dump valve (so a car running 20psi boost only needs a spring set to 10psi not 25psi.)
to:
An optimal set up would allow the blow off valve to open with as little pressure as possible. To accomplish this, we need to equalize the pressure inside the blow off valve under boost and decrease the pressure on the back of the diaphragm only when we close the throttle body. Usually this would be done by running a vacuum line from behind the throttle body to the BOV. This way when the throttle closes, this line would see vacuum and not only would the excess boost on one side push the diaphragm open, the vacuum would help the process. Of course even with this setup there are pressure losses, and the two sides aren't 100% equal (under boost), but close enough that we don't need to install a spring as heavy as what would be required on a dump valve (so a car running 8psi boost only needs a spring set to maybe 5psi not 12psi.)
April 01, 2004, at 05:53 PM by JS
Changed line 21 from:
An optimal set up would allow the blow off valve to open with as little pressure as possible. To accomplish this, we need to equalize the pressure inside the blow off valve under boost and increase the pressure on the diaphragm only when we close the throttle body. Usually this would be done by running a vacuum line from behind the throttle body to the BOV. This way when the throttle closes, this line would see vacuum and not only would the excess boost on one side push the diaphragm open, the vacuum would help the process. Of course even with this setup there are pressure losses, and the two sides aren't 100% equal, but close enough that we don't need to install a spring as heavy as what would be required on a dump valve (so a car running 20psi boost only needs a spring set to 10psi not 25psi.)
to:
An optimal set up would allow the blow off valve to open with as little pressure as possible. To accomplish this, we need to equalize the pressure inside the blow off valve under boost and decrease the pressure on the back of the diaphragm only when we close the throttle body. Usually this would be done by running a vacuum line from behind the throttle body to the BOV. This way when the throttle closes, this line would see vacuum and not only would the excess boost on one side push the diaphragm open, the vacuum would help the process. Of course even with this setup there are pressure losses, and the two sides aren't 100% equal, but close enough that we don't need to install a spring as heavy as what would be required on a dump valve (so a car running 20psi boost only needs a spring set to 10psi not 25psi.)
April 01, 2004, at 05:47 PM by JS
Changed line 1 from:
Author's Note: This is theoretical, and although I will test this in the near future it is by no means "fact."
to:
Author's Note: This is theoretical, and although I will test this in the near future the actual performance increase is unknown. I do doubt a number of the BOV installs that other carbureted Esprit owners have installed.
Added lines 29-34:

Tuning

A BOV shouldn't leak under maximum boost, but stay open under as little pressure as possible. This is a balancing act that really needs to be tuned for maximum benefit. With an adjustable BOV you need to set the spring at the weakest setting that allows the diaphragm to stay closed under maximum boost.

Also, you want to keep the vacuum lines as short as possible to the back of the BOV.

Changed line 45 from:

Stage II

to:

Additional performance increase

Changed lines 49-55 from:
By plumbing your BOV vent back into your intake you can come closer to equal pressure on both sides of the compressor.
to:
By plumbing your BOV vent back into your intake you can come closer to equal pressure on both sides of the compressor.

If you can find a 3 way vacuum solenoid you can run one barb to the vacuum pump (maybe) and the other barb to boost. This way the BOV actually would see vacuum on the back side when you switch the solenoid.

Alternative idea

You could build a mechanical BOV of sorts with another throttle body. It could either be activated by cable or with some kind of vacuum actuator (like on the HVAC controls.) The benefits (if tuned properly) could outweigh a traditional BOV.
April 01, 2004, at 05:22 PM by JS
Deleted line 2:

April 01, 2004, at 05:19 PM by JS
Changed lines 1-44 from:
Describe InstallingABlowOffValve? here.
to:

Page last modified on June 10, 2005, at 11:50 AM