Hammerhd 928 5.3, C5 auto conversion

Hello All

I am new to the forum and this is my first Porsche conversion project. I want to XSchop for the great advice he has shared to date. I am sure I will have many more questions. I have a 84 928s. body is in fairly good condition and interior is in better condition. I have been acquiring parts so that we can begin the conversion in early May. To date I have acquired a low mileage 5.3 from a 04 Suburban, z06 cam and valve springs, the torque tube and transaxle from a low (33k) mile C5 corvette. I will be using Xschop's motor mounts and axles. I am looking for a Ls6 intake..so if you know of one I can purchase...let me know.

My questions:

Can I drop the porsche motor from underneath the car?
What accessory drive works best for this conversion?
Which headers do I need from Sanderson?
If you have done this conversion, what would you do differently if you had to do it again?
What am I missing?
Please share your video and pics of yor completed car to keep me motivated.

Thanks

Good to see you on the path. I just got mine going and it is a blast to drive, accels like a 948 but has more of a tourer feel all around.
I used the F-body accessories. But any of the Vette stuff will work. Maybe even newer truck accessories, just not the early style truck with alternator bracket high on driver's side.

Your big question is weather you will be the first to cut the rear sheet metal to clear factory transmeber or get one of Dinsdale's custom trans members. With his, we already have the conversion axles figured out. But as we discussed, I will make whatever length you need. The engine mounts can have huge adjustment simply drilling the front cross member holes more aft if need be.

xschop wrote:Good to see you on the path. I just got mine going and it is a blast to drive, accels like a 948 but has more of a tourer feel all around.
I used the F-body accessories. But any of the Vette stuff will work. Maybe even newer truck accessories, just not the early style truck with alternator bracket high on driver's side.

Your big question is weather you will be the first to cut the rear sheet metal to clear factory transmeber or get one of Dinsdale's custom trans members. With his, we already have the conversion axles figured out. But as we discussed, I will make whatever length you need. The engine mounts can have huge adjustment simply drilling the front cross member holes more aft if need be.

Xschop, thanks for the reply. I will use Dinsdales crossmember. How much lead time do you need for the items you make? Or do you stock them?

7-10 days on the custom axles. Mounts I have on hand.
The axles are also 4340 chromo and are steady holding 500 hp on Tony's LS3 hybrid.

xschop wrote:7-10 days on the custom axles. Mounts I have on hand.
The axles are also 4340 chromo and are steady holding 500 hp on Tony's LS3 hybrid.

XSchop, I am ready to purchase the mounts.How can I contact you?
Also, which oil pan did you use in your 5.3 928 build?

Thanks

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You have to start a build thread.

To date I have just accumulated some parts and a 84 928s. The parts I have are 5.3L (66k miles) from a stolen/stripped 2004 Suburban. No, I did not steal it or strip it. Purchased the engine from a reputable junk yard. I also have a ported LS6 intake with a ported Throttle body, TT, Transaxle and Bell housing from a C5 corvette. 33k miles on it. Z06 cam and valve springs.

We have dissambled the 5.3 to swap the cam. I hope to have that part complete wby next friday. then we will begin Phase 2... 928 Tear down.

I will post pics this weekend.

Any words of wisdom and encouragement are much appreciated.

EBay turbo for 600hp on all stock assemblies and call it a day. Look at Performance trucks.net quite a few on there. The 5.3 crank is stronger than the LS1 cranks too.

LS engine mounts on their way.

Rob
The Motor mounts arrived today. Your work is amazing!! Thanks

I am gathering more parts and before beginning to remove the Porsche stuff. Any ideas where I can sell the 928 parts (motor, TT and transaxle) Is there a market for this stuff?

928 forum on rennlist. Is it a 5speed or auto?
With a set of axles the 928 5speed will fit a 944.

Auto

Finally got the 928 over to the garage today. I have been busy with work, kid activities and the never ending " honey do list". After a few hours we got the Porsche 4.7 out... That has to be the widest engine I have ever seen. This weekend we will install XSChop's motor mounts and drop the TT and Trans.

Anyone need a 928 drivetrain? It's a automatic. I will try to post pics

When re-sizing your pics, I've found 675 pixels is the widest size that will display fully on the forums here.  Pictures wider than that are truncated along the left edge.  No idea about the height limit yet, so far my pictures have all been wider than tall.

I'm really looking forward to your pictures.  I'm also looking to do a 5.3 swap so you'll be covering much of the same ground I will eventually be seeing.  I'd really prefer to do a swap with the 5.3 +  C5 6-speed, preferably using a set of Z06 differential gears.  I'm not sure how far selling my 5-speed would move me towards that goal, lol.

I would like to see someone weld in an aluminum piece to the weissach once it's been cut in the middle. Carl Faucet just made his fist trans member by grafting in a steel tube that wraps around the Z06 differential and bolts to the two alloy halves.

Hey guys

What harness are you using with your LS swap? What modifications were done? Thanks for sharing

Quick update on the conversion. We removed the TT and transaxle yesterday. We realized that the C5 manual Trans is longer than the auto trans. Not quite sure how we will mount the C5 trans or if the Porsche crossmember needs to be cut. I really don't have any interesting pics to share today, but promise to post pics as we install the 5.3 and C5 Trans. I ordered axles from Rob (xschop).

Any ideas or comments on how to mount the C5 Auto Trans will be appreciated.

Thanks

Do you have the correct torque tube?

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Thanks Rob

Yes, I purchased all the parts from the same auto C5 corvette. I have not actually measured the length of the auto Trans and manual Trans . According to the measurements you have shared, it appears that the overall lengths are the same. I believe the manual has an additional 5 inches between the diff and Trans. The cradles fabricated by Dinsdale and 928 motorsport sit in that space. I have not seen really good pics of Dindales, yet . I will have to contact him next week.

Long over due update

The 928 is now at the body shop. I have not learned how to add pics on this forum yet so I will summarize what I have learned.

First, HUGE thanks to xschop and Dins for their guidance and patience.

1) the motor mounts I purchased work as described and are really nice. We had to modify the mounts to allow the engine to come back an additional 1 inch so the rear bell housing can move higher into the tunnel. You guys with a manual transmission should not have this issue. The rear bell housing should move up about another 1.5 - 2 inches, but I do not want to cut the floor. It should be fine on most roads.
2) the axles I purchased from xschop are great. What you should know. At some point ( I believe 1982), Porsche began to weld the axle stubs to axles. In earlier year cars they were bolted on. You will need 78-81 928 or 930 axle studs to use Rob's axles.
3) the custom trans crossmember works fine

I am forgetting a couple of items. I will add them when I find my notes.

Questions:

Does anyone know where I can find the pressure of the stock 84 928s power steering system
Can anyone provide a part number of radiator that will fit in my 84 928 with the current ports for a LS motor?

Thanks

If you have the shop manuals (or a CD of them) for the 928, both the volume and pressure are listed in the appropriate section. I don't have the values on hand, but have looked them up before.

The information on the axles is good to know, I wasn't aware of the differences.

Sorry I can't help with a radiator suggestion. On my build I'll be re-using the OE radiator at first. I will upgrade from there if needed.

I do have the books. Thanks for the info
Are you using the OE radiator with a LS motor or 5.3? What hose will you use?

I haven't sorted out the hoses yet. My engine is a 5.3 L33 with CTS-V accessory swap that will have a decent cam.

I haven't decided on which cam yet, but I'm leaning towards giving EPS a call and buying one of their cam kits. I'll target something that gives good power, but with a reasonable spread and effective upper RPM somewhere around 6500 RPM. I'm not interested in porting the heads, replacing rod bolts or doing an engine rebuild right now.

I will probably be going with an OEM replacement LS6 intake, the Dorman 615-900, under $300 on rockauto right now. Exhaust details will be decided on later but use a version of the usual Sanderson headers. Having the cam and intake choices sorted first will help define the exhaust.

A quick update.

Transaxle, TT and 5.3 are bolted in. The car is currently in the body shop and the interior is being updated with some custom stitching and other goodies.
The shocks are shot. I am considering 928motorsports upgrade with hyperco springs. If you have made this upgrade... Any feedback will be appreciated.


I can't figure out how to insert pics here using an iPad.
Thanks