1986-88 Bosch CIS K-Jetronic injected Esprit specific items - Page 7 - LotusTalk - The Lotus Cars Community
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post #121 of 253 (permalink) Old 02-15-2015, 08:12 AM Thread Starter
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post #122 of 253 (permalink) Old 02-18-2015, 10:49 AM Thread Starter
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ANTI REVERSION HEADERS

Exhaust reversion on turbo cars could be a real problem, because back pressure caused by a "small" turbine (earlier Esprit Turbos) is significantly higher than on N/A cars.
We are going to state this very clearly...Back-pressure does not increase horsepower! Period.

REVERSION is the secondary pressure wave that travels back up the primary pipes and enters into the cylinder on valve overlap. As this pressure wave travels back up the pipe, it brings with it all the residual gases still left in the pipe. This is what contaminates the fresh intake charge. Stepped headers and ANTI-REVERSION chambers, placed at strategic locations in the primary pipes are employed to tune the arrival of the exhaust wave and to diminish the effects of the high pressure in the pipes. The results are higher volumetric efficiency and more power.

To prevent it, Cyclone and Black Jack products feature a larger sized chamber close to the exhaust port in the primary tube of the header which functions like a step. It's designed to keep the exhaust gasses from flowing backwards into the cylinder before the exhaust valve closes. This helps ensuring that the cylinder gets filled with the freshest intake charge that isn't contaminated with back-flowing exhaust gasses.Like fluid, it's harder for the exhaust gases to travel backwards and upwards over a step than it would be if it was a simple round tube with no steps.

Custom racing headers fabricator USA (perhaps better/cheaper than Alunox): about us

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post #123 of 253 (permalink) Old 02-18-2015, 05:53 PM Thread Starter
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Anti-reversion chamber(s) replacing mufflers?
Interesting idea.
Here are the pictures how to make one: http://www.realhomemadeturbo.com/for...c,13772.0.html
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post #124 of 253 (permalink) Old 02-19-2015, 07:01 AM Thread Starter
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post #125 of 253 (permalink) Old 02-19-2015, 05:17 PM
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The problem with this technology is that it is very "tuned" to a particular volume-RPM range. Difficult to make it work over a wide range of RPM's. Typically what is done is it is optimized to a specific range and then you try to reduce the bad effects at other RPM's or move them to a range that you are not in as much. As much as this is very scientific, after crunching the #'s you then build it and through trial and error make it do what you really want. This is NOT bolt-on technology. When you are all done you won't see all that much gained for what you invested in time and money. In racing where any amount of improvement is worth doing it can make sense. You also see this kind of stuff on the intake side. It is also done to try to reduce noise. By setting up standing waves you can cancel out some noise. Again very RPM specific.
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post #126 of 253 (permalink) Old 02-25-2015, 08:42 PM Thread Starter
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Citroen C35 Transaxle inherent weakness

Originally, Citroen C35 gearbox was designed to run in the opposite direction on Citroen DS and SM and therefore the CWP profile is "backwards" for the Lotus/Maserati configuration! The teeth on gear sets have both a drive side and a coast side. Usually the pinion should rotate the crown wheel on the drive side of the tooth. If however the pinion rotates the crown wheel on the coast side, strength of the gear set can be reduced by as much as 20%.
Lotus CWP is weak in forward drive; its strength is better in overrun!
Have a look on Google for the driven and coast sides of the gear and the slope differences.

Similar situation exists on the front Land Rover differential.
In the front axle of a Land Rover, the gear set is running “backwards”, being driven on the coast side of the teeth rather than the driven side and as such is weaker. Reverse cut gears are required in this configuration!

There are only a few Specialty Gear companies which have produced reverse rotation gear sets to allow the gears to be driven in the correct way. This also allows the pinion to transfer the load forces into the bigger pinion head bearing rather than the smaller tail bearing, such increasing the life of the bearings.

The solution (?) would be making a NEW SET featuring reverse-cut gears! I have been quoted $1800-$2000 per set.
I can't establish a communication with KAMdiffs, their mailbox is full. http://www.kamdiffs.com/products-2/diff-ratio/

HOW MANY OWNERS WOULD GO FOR IT?
Is there a desire to keep polishing the old turd?
It is probably more economical to drop used 915 tranny and call it a quits.

Also have a look at the Citroen box oil flow when the box is rotating in the intended direction, notice the drain going into the 5th gear extension.
Now, notice what happens when the lower gear clusters are going the “wrong” way!
And imagine that.... Lotus has 5th gear oil problems!

.
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post #127 of 253 (permalink) Old 03-28-2015, 11:30 AM Thread Starter
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Mechanical Turbo Boost Sensing WUR

FYI,

Anytime you upgrade the turbo or increase the boost, it will be necessary to add mixture air/fuel ratio control device.
There are a couple of ways you can "skin the cat". LOL.

One of them is a Digital WUR:
the FrankenCIS project
http://forums.pelica...frankencis.html

For those who want to stay purely Bosch Jetro "mechanical" (no computers/processors/maps/data logging, etc.), the solution is a Volvo 240 Turbo boost sensing WUR (w/longer warm-up time), Bosch PN# 0438140123 . The only modification required is an addition of the Warm Control Pressure adjustment feature, as shown on pic 3 &5.
Everything else stays the same.

Any time you play with AFR, or remove the spacer ring from the waste-gate stack up, adding J&S Safeguard Individual Cylinder Knock Control is a cheap insurance against melting the piston(s).

J&S Vampire

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post #128 of 253 (permalink) Old 03-28-2015, 12:02 PM
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I would not waste much effort on the WUR (aka control pressure regulator) because if it is working as it should, once the motor is warmed up it really doesn't have much effect. In some applications it also functions as an accelerator pump, giving a short burst of enrichment on sudden opening of the throttle. Again, as long as it is working as it should and is hooked up as it should be. They do lose their calibration and the internal heater burns out. Although they are very specific to application, the # describes it's specs, they can be recalibrated to different applications. In general you should try to stay as close as you can to the original Bosch parts since they were all selected to work together. Not a whole lot to be gained modding the K-Jet unless you made other changes that will necessitate changing the fuel system. For a lot more info on modding the K-Jet system get Bosch Fuel Management & Engine Management by Charles Probst.
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post #129 of 253 (permalink) Old 03-28-2015, 09:26 PM Thread Starter
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David is right,
Probst book is an excellent primer on CIS and a "must" reading for anyone who owns Bosch injected car.
Another book worth reading is "How to Tune and Modify Bosch Fuel Injection" by Ben Watson. This book has more practical, "hands-on" approach. Both are highly recommended. Additional online reading about CIS tuning:
VWVortex.com - CIS, CIS-Lambda, CIS-E and CIS-EM FAQ and Tuning Guides

Modifications described above (in post #127 ) reach over and beyond the scope of these books and are based on empirical experimentation encountered on Pelicanparts, Rennlist, Turbobricks and couple other Forums. : http://forums.vwvortex.com/showthrea...-Tuning-Guides

David is right in saying, that you should not consider replacing OE hydro-mechanical WUR with digital (DWUR) or boost sensing unit, unless you're going to install larger turbo, increase boost or radically improve the air mass flow.

Bosch CIS system is quite flexible and able to adjust to some improvements in the air flow. Contrary to the popular belief, CIS system delivery is not limited by injectors (mechanical injectors have no duty cycle), but only by the fuel distributor.

CIS Esprit engine has a couple of choke points:
1. Turbo is intentionally "smaller" to provide snappy response and a minimum lag. Unfortunately, it creates a significant exhaust gases back pressure.
2. Turbo-to-down pipe adapter bore ID is smaller than the turbine port ID (!)
3. Mass Air Flow Meter is maxed out (only 108mm) to flow any significant additional amount of air.
Until you remove these performance obstacles you don’t need to replace the WUR.

My point: If you introduce radical changes, you'll have to take care of the continuous enrichment under boost in order to avoid engine damage. Therefore,
the Control Pressure has to be modulated via continuous WUR adjustment in function of the rpm and MAP. Some Turbobricks forum prefer another method, i.e. grounding pin #11 ("accelerator pump" of the CIS ECU). [URL=https://www.lotustalk.com/forums/usertag.php?do=list&action=hash&hash=11].
http://www.turbobricks.com/mods.php?content=art0021
It can be done either digitally, with an application of the UTCIS "PT" Digital WUR, (UnwiredTools UTCIS-PTâ„¢ ) or mechanically by applying the IM plenum pressure signal to one side of the diaphragm in the WUR lower chamber. Boost sensing WURs were used on 1980-s Volvo turbo, Audi TQ, MB, Saab, Porsche, BMW, etc., but mysteriously Esprit was outfitted with bare-bone N/A-type CIS system (another example of a cost avoidance).
FYI: some folks made about 345hp with 4 cylinders Volvo! Group A Volvo Specs

On the car equipped with a single lambda sensor and a rudimentary CIS system,
“Vampire” ant-knock processor is a cheap engine Life Insurance and is always worth implementation, even if you leave your car “stock” (for explanation WHY - see my post # 68).

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post #130 of 253 (permalink) Old 03-29-2015, 09:33 AM
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The K-Jet has some inherent limitations which prevented much further technological improvement. It is a mechanical continuous fuel injection system with a very linear range. The mass air sensor, the air sensor plate and venturi, create a significant choke point for airflow. The mechanical linkage between the air sensor and fuel plunger can only work linearly and is not adjustable except over the whole range. The Lambda system cannot make large corrections quick enough to handle transients. Once digital systems became robust enough to be used in automotive applications they were far superior to the mechanical ones they replaced just as the mechanical fuel injection systems replaced carburetors.
In the Delorean world where we are also "blessed" with K-Jet, there are some who advocate ripping the whole system off and going to carburetors. Not many. There are also some who have ditched the K-jet for electronic systems. No small accomplishment because of the fuel mapping necessary to get it to work. Unless you are doing a whole fuel system because of other mods it makes no sense to change. Parts and service is still available to keep the K-Jet going unlike the Delco brake system in the S4 and S4s. What kept the K-Jet going was the ability to adapt it to forced aspiration easily. There have been many patchwork attempts to get more out of it from all kinds of enrichment systems to water injection. Being a mechanical system it is easier to do mechanical tweaks. If you are planning on doing radical changes to the motor then you must consider an electronic fuel system to keep up with them. Much easier to modify and make running changes once installed.
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post #131 of 253 (permalink) Old 03-29-2015, 06:10 PM Thread Starter
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I respectfully disagree.
Once you understand how the system works, it is not that difficult to modify it.

CIS K-Jetro injection must have not been so "evil" to find its way on so many (exotic) cars.
Check for yourself:

Bosch K-Jetronic fuel injection

.
.

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post #132 of 253 (permalink) Old 03-29-2015, 06:27 PM
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Quote:
Originally Posted by MRDANGERUS View Post
I respectfully disagree.
Once you understand how the system works, it is not that difficult to modify it.

CIS K-Jetro injection must have not been so "evil" to find its way on so many (exotic) cars.
Check for yourself:

Bosch K-Jetronic fuel injection

.
.
I never said it was "evil". In fact, at that time it was about the most advanced system available. By today's standards it seems archaic but that was then and this is now. Modding the K-Jet is possible but any improvements will be negligible. As I said, the only reason you would need to modify it is because you did other mods to the motor that would require mods to the fuel system. Otherwise keeping it stock in the best running condition possible is the way to go.
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post #133 of 253 (permalink) Old 03-29-2015, 06:30 PM
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post #134 of 253 (permalink) Old 03-30-2015, 11:18 AM Thread Starter
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post #135 of 253 (permalink) Old 03-30-2015, 05:22 PM
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David,
Could you tell us please, what and how many CIS cars have you had/worked on in the last 10 years?

A lot of Deloreans and a Lotus or 2. Some of the Deloreans had turbos.
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post #136 of 253 (permalink) Old 03-31-2015, 11:39 AM Thread Starter
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Since the days of DeLorean CIS technology has leaped forward.

Mechanical system modulated by digital processors actually can achieve more control over the air/ fuel than any of the other stock systems.

To stay current everybody should read UnwiredTools UTCIS-PTâ„¢
and accept the fact that the modern technology made previously unimaginable things possible.
With this device CIS system can be converted to operate in a digital mode with full spark and fuel mapping. There are a couple of Esprits in US already equipped with this system and they pack a wallop.

BTW, I posted this in the past, but it must have escaped your attention:
Group A Volvo Specs
345hp with 4 cylinders Volvo!
Is this a "minimal improvement"? LOL

I rest my case.
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post #137 of 253 (permalink) Old 03-31-2015, 11:52 AM
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Originally Posted by MRDANGERUS View Post
Since the days of DeLorean CIS technology has leaped forward.

Mechanical system modulated by digital processors actually can achieve more control over the air/ fuel than any of the other stock systems.

To stay current everybody should read UnwiredTools UTCIS-PTâ„¢
and accept the fact that the modern technology made previously unimaginable things possible.
With this device CIS system can be converted to operate in a digital mode with full spark and fuel mapping. There are a couple of Esprits in US already equipped with this system and they pack a wallop.

BTW, I posted this in the past, but it must have escaped your attention:
Group A Volvo Specs
345hp with 4 cylinders Volvo!
Is this a "minimal improvement"? LOL

I rest my case.
I understand there is newer technology available. I work on it all the time. Instead of grafting patches onto older technology some Delorean owners have ripped it all off and gone with a fully engineered system like M/S (MegaSquirt). IMHO if you are keeping the engine stock there is little to be gained replacing a properly functioning K-Jet system with newer technology. I say this with due consideration to all of the work and the expense involved. For what you will invest it isn't worth it. Don't forget, you can't take it to a Lotus shop to have it serviced anymore, they will not be familiar with it unless they did the install. It will have an effect on resale value too. In some States you cannot pass emissions testing because it is not OEM. It is not just about getting a couple of more HP. There are other factors to consider. As for your 4 cyl with 345 HP, just how long will it last? For a street car durability is more important than in a race car. We can get over 1,000 HP from a V-8 for about 1/4 mile for at least a couple of times!
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post #138 of 253 (permalink) Old 03-31-2015, 12:49 PM
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David has an AWESOME mustache.

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post #139 of 253 (permalink) Old 03-31-2015, 12:50 PM Thread Starter
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No need to be ALWAYS SO NEGATIVE!

Have you ever heard about the Positive Reinforcement?

HUH?

Seems you forgot... on this Forum, we supposed to help Lotus Owners and instill encouragement!

This discussion is utterly counterproductive.

Ciao!

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post #140 of 253 (permalink) Old 03-31-2015, 02:48 PM
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No need to be always so NEGATIVE!

Have you ever heard about the Positive Reinforcement?
LOL

Seems you forgot... on this Forum, we supposed to help Lotus Owners and instill encouragement!

This discussion is counterproductive.

Ciao!
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