gbgastowers

The oil in the exhaust could be blow by from that cylinder. Looks like that piston had gravel or some foreign objects in it maybe from debris entering through spark plug hole. Gunar

namasgt

#7 looks like a broken ring, but you said the leak down for all the cylinders were close. Some of the damage you see on the piston could be on the head too, some welding and resurfacing should fix it. I would just yank the motor out and start looking for a 85-86 5.0 short block.

AO

Pretty sure all of that is from knocking. If you look at the previous for-sale thread from Iwanna928, DR posted picks of the plugs that came out and they looked horrible with little aluminum bit all over them.
As for the source of the oil being blowby on #7...I don't think so... but maybe. There is a lot of white smoke from the exhaust on decel! And the oil breather stuff has oil leaks all over the place. It's got to be that crazy setup. I want to at least cap the system. If I do that then there will be no question of if it is the source of the oil in the exhaust or not.

I agree #7 is probably a broken ring. But there is nothing I can do about the block now. The pistons are also toast. The heads might be salvageable.

Since this is an 85 Euro, I was thinking about making a hybrid as well. I know of an 85 short block that I might be able to purchase locally... or maybe I will get one from 928 Intl when/if they do another 1/2 off end of year sale.

James Bailey

Actually 25-35% leakdown is pretty horrible and the amount of blowby from that is HUGE ! Just imagine what it then becomes under boost . The thing becomes an oil pump ....total waste of time tuning a dead engine.
The only reason to keep it running is so the wife thinks it still is a car.

AO

Well I don't put too much faith in the accuracy of the HF leakdown tester. It idles and runs decently. But your description of it becoming an opil pump might explain a lot...

I guess this isn't a shocker. I knew the car had issues when I got it. But part of me was hoping it wasn't this bad.

James Bailey

From a Mobile 1 site ......"Reading Results
No engine will have perfect sealing with zero percentage loss. Five to 10 percent loss indicates an engine in great to good running order. An engine between 10 and 20 percent can still run okay, but it’ll be time to keep an eye (or ear) on things. Above 20 percent loss and it may be time for a teardown and rebuild. Thirty percent? Major problems. The percent of leakage should also be consistent across the cylinders. Any great differences indicate a problem in that cylinder."
Like I said....it's dead.

AO

Thanks James. Well I guess I now know what my path is going forward. I think i will still "tune it up" so I can drive it around a bit and have a little fun. But this winter, it will be all about sourcing and building up a new block.

Lizard928

If its to remain boosted then go with a 4.7L USA bottom and for lower CR and more boost.....

What are you using for those cylinder pictures?

John Speake

If you're thinking long term, then sourcing an engine from uk or Europe may not be out of the question, a short engine, sent by sea might not cost too much.

BTW, please include a Vampire knock control system in your plans !

BC

Andrew- e85 - do you have it where you live?

Imo000

Nice project, finally a thread worth reading.

Leakdown testers are fairly basic instruments. Rod (Gaugeman69) made one, using household items and I've used it a couple of times.

You can check the accuracy of your tester against a good engine, like your GT or any other engine. James is right, anything into the double digits is a concern and 35% is terrible. I'm sort of "rebuilding" a 996 right now and the carbon build up on the exhaust valves caused a 15% leak. Once all cleaned up, it dropped to around 3-4%. 4.7s are dime a dozen, I would use one for this project. That 300cc won't make much of a difference anyways.

Jon B.

John, is the Sharktuner directly compatible with the J&S systems? I was looking at the Vampire system, and it seems it's mainly for COP ignition systems. What's funny is that it's something I was considering for my Lightning. So, more information with your experience would be great. I know the Lightning guys that run their systems swear by them!

Tony

What he said! great quality. I saw one at HF for about 190.00 the other day.

or...

is this the one you homo's stole from the gynecologist

AO

Yeah, I'm thinking 4.7 might be the easiest and cheapest way to go. As for the camera see my response to Tony below.

well... If I want to keep it boosted (which I do) then another hi compression motor might not be a good choice. I can pick up a cheap 4.7l here for next to nothing and use the high-flow euro heads and SCer and should make some good HP. But yes, I want knock detection. Will look into the Vampire system when I get that far.

yes we do. But this SCer is already pretty much maxed out. I don't think I would gain anything (power wise) by going to e85 with this SCer. If I put a 2.8l, then yes, but that would be a big endeavor.

Thought about trying it on the GT for reference, but am scared about what I might find out.

Gynecologist? No way. It was a Proctologist..

Kidding aside, Z turned me on to this. You can find them on eBay for about $20 shipped. Search for USB endoscope. The have little LEDs on the end and work great. Just need to plug it into a laptop. The business end fits right down through a spark plug hole. It's hard to maneuver, but with a little patience you can usually capture the image you're looking for. Pick one up. You'll be glad you did.

BC

You may wish to look further into that. Depending on what is happening with the boost, you will at least get the 5% for the mere fuel switch, and then the additional timing that is available, and once you have the newer engine in, it will completely remove the possibility of detonation.