Hvithaien

Hi!

I have 1984 928S US with the L-jet injection. I am looking into replacing my intake system (plenum, spider legs, and throttle body) with the intake from a 1984 Euro (LH). I have all the parts needed to do the job, but I have couple of questions before I dive into it:

1. Will the L-jet injectors be "plug and play" with the Euro/LH-jet intake runners, or do I have to do some machining to make it work?

2. I see in a thread here on rennlist that others have spent hours grinding the inside of the US-throttle body "U" to make it the same inside diameter as the euro throttle body. Why can't I just make up an aluminium ring to act as an adapter between the L-jet MAF and the Euro/LH-"U"?
If all the other dimensions are the same, I think that would be a much better solution. Any thoughts?

-Hvithaien

Ducman82

I'm pretty sure the injectors will bolt on. And u can make a seal ring, but that barn door (afm) will be a real limiting factor.

Hvithaien

*Bump*

Anyone got the definite answer to my questions?

-Hvithaien

IcemanG17

the runners themselves are only slightly bigger... .1" The increased flow comes from the much better MAF and throttle body assembly....

It is fairly easy to do a AFM to MAF conversion, all you need is a conversion kit like this

http://www.splitsec.com/products/mafkits/MAFkits2.htm

The injectors are the same.....

mark kibort

its all really straight forward. the griniding takes only 15 mn, with an air grinder, with a dremel, its an hour job. (with lots of those throw away rings.. use the porsche U and do this . however, if you are using a MAF, then use the euro U its already bored way out for the maf to begin with. use all the stock stuff and modify it, it alows you to use the stock airbox which is probably the best too.
injectors bolt right on. no issues, however there are a few little things that need to be adressed if you want to use cold start, which you WILL. otherwise, hard to start the car. you want it to run the same, make all the stuff work the same, just modify. cold start , for example would be routed to the plennum vs the head intake ports as the US Ljet has it set up. this creates a very easy routing mod requirement.
i also think there becomes a requriement to pug a hole in the U as well, which is easy with a hose and a big ball bearing for a plug. the euro throttle body is better too, because it has the WOT and IDLE switch already connected. the US switch is a little old school and exposed. (and a pain to set up on the euor throttle body if you want to use it as the brackets and mounts are not there)

Hvithaien

Since I am not replacing the heads, I guess the cold start valve/injector can stay where it is. Right?

So replacing the spider and throttle body should be more or less plug&play.
The euro throttle body got only two vaccum fittings (US got 4), but I only need two because I have deleted the air pump and the vaccum line to the diverter valve is gone..
And the connections on the U's are similar, so that is plug and play too, except for the diameter conflict of course.

I am a bit bored, and since I have all the parts gathering dust, this should be a nice weekend project..

Hvithaien

robot808

You also need to find a way to get the line from the oil fill to the U for crankcase ventilation. That takes a little ingenuity.

Hvithaien

If I use the euro-U, it should not be a problem. It is already at an angle to avoid hitting the idle/WOT switch housing.

-Hvithaien

soontobered84

The injectors are the same only as far as mounting goes. The impedence is different. You will need to use your L-jet injectors which are currently mounted to your fuel rails. The fuel rails are the same for L-Jet and LH 16 valve cars.

Hvithaien

A full set of gaskets and O-rings for the intake and throttle body is on order.
I also ordered a full set of coolant hoses. On of my goals with my 928 is that it should be a 100% reliable car, so better safe than sorry with 28year old hoses.

Snapped a picture of my car tonight.

-Hvithaien