should I skip the 99T lambda system to get more power?

[nlviking]

I am currently restoring a California 99T and since I live in Europe, the lambda system is not required on cars before 1992. An European 99T has 10 BHP more: it is lacking the catalytic converter and instead of the lamda system there is a simple enrichment system with a bigger air valve.

I am considering which system to install. I want to evade unneccessary power blockades, but at the same time keeping the work within limits. Also I want to raise the turbo pressure a bit, install a TD04 turbo with 3" downpipe and an intercooler.

My question is as follows: is the lambda system purely an environmental limit, or is it also a technically sophisticated system that will not stand in the way of the little tuning I have in mind?

Your contributions will be appreciated!

[nlviking]

[nutcase]

I think you'll also find your car has a 4 port fuel dissy, whereas the non-US ones have 6 port.

[nlviking]

yes that is the case. And the air valve is smaller on the US version. But does it really matter in practise?

[Crazyswede]

Car looks fantastic.

if you want more power you should just skip the CIS system altogether. You could get a Djet manifold and run modern injectors and one of the many modern injection systems. Someone on this list made an adapter for a megasquirt computer to run through a stock LH harness. Combine that with the Djet manifold and you could do a very clean install....more power, less clutter, and more efficiency. It all comes down to the purpose of your restoration...do you want a factory replica or a nice looking car with some modernization.

[nutcase]

A standard non-US K-jet is good for at least 175bhp (I added APC for peace of mind) with no modifications. With mods such K-Star 220bhp is perfectly doable.

[DrewP]

A standard non-US K-jet is good for at least 175bhp (I added APC for peace of mind) with no modifications. With mods such K-Star 220bhp is perfectly doable.

Exactly the information I was hoping would pop into this thread.

[nlviking]

Car looks fantastic.

if you want more power you should just skip the CIS system altogether. You could get a Djet manifold and run modern injectors and one of the many modern injection systems. Someone on this list made an adapter for a megasquirt computer to run through a stock LH harness. Combine that with the Djet manifold and you could do a very clean install....more power, less clutter, and more efficiency. It all comes down to the purpose of your restoration...do you want a factory replica or a nice looking car with some modernization.

Thank you. My initial thought was that the lambda system (you call it CIS?) is restricting the fuel supply, so I could just as well install the European system. But perhaps it is not really restricting? Perhaps it is regulating much better, and the restriction (compared to the European system) is in the catalyst. That is actually my major contemplation.

The D-jet manifold in combination with megasquirt is very interesting, I happen to have these on the shelve here (did not know this was possible), but for now it is too much work. I do not want an exact replica (I plan to fit a TD04 turbo compressor also) but I do not want to invest too much time in modifying either (at this moment). Maybe in future.

[nlviking]

A standard non-US K-jet is good for at least 175bhp (I added APC for peace of mind) with no modifications. With mods such K-Star 220bhp is perfectly doable.

Well could a US K-jet do more, or less, and why? That is what I would like to know.

[Geoff]

We call K-Jetronic "CIS" in the US
http://en.wikipedia.org/wiki/Jetronic

The Lambda system was designed for emissions control and samples the fuel mixture in the exhaust and tries to adjust the fuel mixture being injected into the engine in an attempt to regulate emissions. The early systems (like on the 99 Turbo) worked OK but Bosch continued to try to improve the system and kept adding more sensors to compensate for issues. It was sort of like putting a bandage over a tattoo, the tattoo may not be seen but it doesn't go away.

With these older electronics, the less complicated you can make it, the more simple the system, the easier things should be.

[nutcase]

Pedant mode: K-Jetronic is a type of Continuous Injection System :) But yes, pretty much interchangeable terms :)

The US 4 port fuel dissy has a lower capacity. The 6 port (with 2 blanked off) can flow that much more for higher output. Or if you really want to go to town, get one off a Porsche 928 - what they used on the rally cars.

K-Jet may be basic, but it works. I like it. But then I like the B engine too. Only thing I'd like to do with mine is a more accurate ignition system. Although I'd prefer it to look externally identical.

[nlviking]

Let's say I will use the 6 port fuel dissy - will the lamda system regulate it down?
Does the lambda system work with an on/off system, or does it give pulses?

[Crazyswede]

Let's say I will use the 6 port fuel dissy - will the lamda system regulate it down?
Does the lambda system work with an on/off system, or does it give pulses?

The lamda system used a basic O2 sensor which when through a very simple computer...think the great great great grandfather of a calculator...which then regulated a frequency valve. The frequency valve only has so much range so its not like a modern system that will cut things down and override your modification.

[DeLorean]

you should check out the manuals to see how the K-jet system works. Basically the lambda system adjusts the control pressure via the use of a fuel injector (either leaner or richer) only under certain conditions - (never under full throttle)... you CAN do away with it, but it will need a bunch of adjustments to get it to run right if it's a CIS-E system.

[SwedeSport]

I can't wait to ditch the CIS on my 86 8v car. Was thinking carbs, but lately leaning towards ITBs.

Besides all the tuning issues, CIS system is considerably heavier than the alternatives.