Difficulty of a 1985 928 5.3 LM7 swap.

A little about me. I'm 21 years old, currently go to university on a BS degree. I have a lot of experience with the porsche's, volkswagen's, and old corn binders! I'm fairly handy with a wrench. I'm ok with a mig. I have been debating the idea of swapping in a GM 5.3l engine for awhile now in my 928. Since my 85 needed a top end rebuild which is quite expensive, as well as performance parts that take a toll on more then just the wallet. I have finally pulled the first string on a 5.3l out of a 04 tahoe. It was a complete pull out for 850$. " which was a fair deal"?
I have been reading tons of threads, and the most helpful is xchop's over on rennslist. Here is where I'm at.
I think the hardest concept I'm trying to consider is keeping the throttle by wire vs cable. Is the throttle by wire reliable, or would it be worth switching to cable?

• Would the stock ecm be able to run the engine by flashing it and tune, or would a piggy back, or stand alone system needed? If it's worth the latter options, recommendations of which one to run?
  

I also curious to keeping the stock gauges working, but I'll cross that bridge when it comes to it.


I have a open garage and free summer. Show me the way!   


Also if anyone has any conversion parts let me know!

Swapping in the LS engine into a 928 is MUCH easier and much less expensive than swapping a 944/951.
I've done both and designed my own parts along the way. I have the bare-bones kit for sale ($595 shipped US-48). There are a few people that are starting the swap with it. I designed/machined the adapter so that the input shaft sets in further 0.400" eliminating the need for an LS pilot bearing adapter like the 944 swap kit requires. Factory vac booster, factory radiator, and factory gearbox stay put with the 928 swap. Some of the 928 guys say the manual boxes are good for 300rwhp. That said, I designed the 928LS engine mounts so the drivetrain can be set back another 1.5" to get the 6speed vette torque tube and trans mounted. I worked with Dinsdale on a couple of them and I have made the conversion axles for that as well. He installed the wire pedal in his latest LS3 swap and said it was super easy. Just check out "Just Peachy" swap on RL. He started swapping in his Toyota V12 if that gives any indication the amount of engine bay is available for the 928 compared to 944. Post lost a pics.  

Finally pooling more money into the project, and time. "Finals end on the 6th"!
So after countless hours looking into oil pans that should be used on studying, also having a really good TIG welder locally that is really reasonable if I do all the prep. I am leaning towards modding the truck 5.3 oil pan to fit!
Would .125 inch 3003-alloy suffice, or should I go to .090 (2.3mm)?!  

You have .125 go with it, if not a little thicker would work better. The truck pan would be a good one to mod for sure, just cut area near sway bar first to make sure it clears.

Maybe off topic question.
How much those truck LS engines weight?

Those got aluminium heads but iron block.

Just that I can find locally reasonably priced LS (LQ9) from Escalade and it is similar than those tahoe engines? So instead of purchasing new LS engine (LS 327 or LSX376) I could try that one out, as its low mileage and comes with all accessories and EFI stuff.
Just to get the car moving again... and still that LQ has 100more hp and allmoust 200nm of toque more than the original 4,5 I have so the car would be faster with it.

Actually, the extra 75 lbs will allow you to keep the stock springs. I had to cut 1.5 coil turn off mine with the LS1.
And L92 heads will bolt onto the 6.0L

Ok. Thank for the input.

Need to consider that then.
I have a adjustable suspension setup in place so I can adjust it a bit anyhow depending on the weight of the car.
The car will be anyway lighter than original (interior and insulation,smaller fueltank etc) so I will need to fiddle with it..