IceCold4x4

So I have an 82 us spec manual 928 4.5 with L jet and a m28/11 4.7 euro s motor here. How hard would it be to swap the 4.7 into the US spec car and retain the l-jet?

IceCold4x4

It seems like I would be ok to swap the long block in and use the L jet runners, and everything should be bolt up. Leaving me the question how will L jet respond to the increased air flow? And how can it be tuned?

The Forgotten On

It will respond fine. It's only like a 5% increase in flow which it can handle in open loop operation and will still be fine in closed loop operation under load.

I'm going to run my L jet on a 5.0 which has been done and works fine.

You can tune it using the CO pot on the AFM to set the proper fuel to air ratio using a wideband O2 sensor.

IceCold4x4

Perfect just what I wanted to hear. I'll start pulling the 4.7 next week and give it a once over and make sure it's still a viable candidate.
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IceCold4x4

Was hoping more people would have done something like this from what it sounds like, I think I saw where a guy kilbort (sp?) had commented on a few of the mechanical part swaps on keeping cis to cis but I didn't find any mention of the other possible issues one might run into on keeping the l-jet as everyone wants to keep cis.

The Forgotten On

Kibort wants in on this thread as well. You can PM him to get more in depth info. Now for some more of my thoughts

Porsche stuck the same L jet parts on the 4.7 as on the 4.5 here in the US. Same part number from 81-83 (83 got the 4.7).

If you can get one, you could stick on a later fuel computer as a nice placebo

The tension of the spring inside of the AFM controls the A/F ratio under load. The CO pot controls the A/F ratio under all circumstances as from what I can deduct from the WSM.

Loosening it a few notches will make the barn door in the AFM open easier and allow more fuel to get injected earlier depending on how open the throttle is.

This will be your main adjustment to worry about, install a wide band O2 sensor and dial it in to stoich ~14:1 A/F ratio when under partial load (before the WOT switch is tripped, which should be when the throttle gets more resistance).

Regarding the CO pot on the AFM. You need to adjust it based on the pre cat measurement of carbon monoxide ( CO ) using the test port under the catalytic converter to 0.4-0.8% CO.

There is more info on this in section 24-01 of the work shop manuals. I hope this helps.

danglerb

The size is not much difference, its the heads, cams, intake, and maf on the Euro that makes the HP. The whole Euro with brain to match makes something like 50 to 60 more hp than the 4.5 at the rear wheels. Use less, get less.

IceCold4x4

Ive got the donor euro s so I can swap. Everything that's possible, just don't want cis.

Mikebte

IceCold4x4

The US car is already a 5spd and ya I'm going to pull the heads at a minimum and change head gaskets and inspect the bores and decide from there. Still a possibility that the 4.7 is trashed thus causing it to become a parts car in the first place.

danglerb

I'd start with the compression check, but nothing beats a full tear down and inspection.

The Forgotten On

Here is what Mark Kibort sent me since he cannot post here. I do recommend contacting him directly as he has done this a few times before.

its killing me that there is so much mis information on this already . the AFM can handle the mass flow change.. more air, means more deflection means more fuel its adaptable to 290rwhp with no issues. slight bump in fuel pressure is required. i have a few ways i did that. RRFR plus some tweaks did the job

the gains are in the cam , and intake and heads. some mods are reqired to make the cold start work thats easy, but required. (euro heads different than US heads with regards to cold start ports vs emssion ports at rear of heads)

sounds like he has a 80 -83 euro, which means CIS and he doesnt want CIS. so , he needs to find euro runners or hog out the US runners and then use the CIS TB and plennum... THEN, adapt the AFM "U" to the larger throttle body with small mods to make the idle switch and near full throtttle switch work.

the 4.5 US cams are the worst of the bunch. Nothing will help them, so the use of the euro 80 or 84 cams work great .

sounds like that is the best option if he wants to get away from CIS but still use the euro 4.7

maybe you can cut and past this.... (or paraphrase)

STRIKEMASTER

Does the 4.7 engine run well with the K-Jet? If yes, why not keep it?? Just hook up the fuel lines, wire it in and go have some fun...

IcemanG17

In an ideal world get an Euro LH intake that has electronic injectors.......however just dropping the 4.7 euro S long block on top of your USA intake is super easy and will work fine.....as mentioned above you probably will have to adjust the AFM to increase fuel or could install an adjustable fuel pressure regulator to tune it properly. No matter what its a worthy upgrade and will increase performance quite a bit......