ceedee

what would be the better in your opinion and why?

hacker-pschorr

Thinking of converting your cars to CIS?

right now I would choose L-jet becuase CIS parts are becomming very hard to find.

I own both & prefer L-Jet because it's easier to supercharge. I'll be converting the 79 to a 3rd party EFI before boosting.

ceedee

the k-jet supercharger seems to be cheaper at carls place.
cheaper than the L-jet

Daniel Dudley

Ljet is simpler and gets better gas mileage. The better one is the one in the car you are working on, esp. if it is working. A lot of the racer boys are taking cis OBs and doing 5.0 conversions. Seems to have the capacity for over 300 HP without too much fussing.

Airflite40

if CIS was better, Porsche would have stuck with it.

many will say that when CIS is well tuned, it runs very well and is very reliable.

IIRC CIS was used until the 90's on some MB's, Audi's etc.

SharkSkin

I like CIS because it's so simple, there is very little that can go wrong once it's set up correctly. Borys, I guess that puts me in the "many will say" category. 3 years, 25K miles since it was last tinkered with, runs as good as ever. It seems to have better throttle response than L-Jet too.

Daniel, I'm not sure how you figure L-Jet is simpler -- there's that whole brain/O2/injector wiring/plumbing thing, and the AFM.

jpitman2

I am also a fan of K-jet, ONCE it is working ok. No brain to fry in the electrics, just keep clean fuel up to it, use regularly! As much or more power than L-jet, but not as economical (should not be a consideration here?). I have seen it used on Ferraris into the 90s - two units on a Testarossa. I suggest it was dropped due to failing to meet tightening emissions regs more than anything else, and the improvement in the ability to computer control injections systems.
My 83 never ceases to amaze in how well it works - from a stone cold start I can drive away with never a miss or cough or any sign of incorrect mixture.
jp 83 Euro S AT 50k

mark kibort

Ljet is pretty simple, and is easy to tune around. HOWEVER, the restictive AFM opening is a major drawback. think of it as a 50% restrictor plate !

mk

SharkSkin

I figure if the euros made 300hp with K-Jet it can't be all bad...

Pfunde

yeah..........

mark kibort

If the Ljet 4.7s can make 265rwhp with the euro top end and intake hardware, they cant be all bad either![ (and support 290rwhp by adding a 5 liter bottom end) If we could find a way to open the intake by using two of the AFMs in parallel, the Ljet could work as well as CIS as far as raw power potential. that 50% restrictor plate with the Ljet has always been a thorn in my side. (well, its in Scot's side now )

mk

QUOTE=Pfunde] yeah..........[/QUOTE]

hacker-pschorr

That is the key.

Friend of mine who has been working on German cars since the early 70's has had it with CIS. Parts are impossible to find (even for VW's) and when you find them they cost a fortune.
Didn't that setup also have upgraded exhaust?

SharkSkin

After spending $1200 for a set of NOS 1970 240Z carbs for my old Franken-Z I have yet to flinch at the prices of CIS parts -- though the fuel distributors are a bit spendy. OTOH they generally just need fresh o-rings when they start misbehaving, AFAIK.

PorKen

You could make a bypass around the AFM. It would be great if you could just loosen the vane spring to compensate, but you'd probably need an electronic tuner regardless - (Autospeed bypass article). If you have to have a converter, you might as well put in a MAF conversion, like on Kuhn's turbo.

mark kibort

oh yes, upgraded MSDS headers on the exhaust side with a couple of mufflers and a 3" pipe.

mk