Marine Blue

You’ve taken this hobby to the next level Anthony, that is an insane amount of effort! But alas its something you also enjoy so perhaps not really work. The results so far look incredible, can’t wait to see the fully assembled final product.

jpoint

I'm glad you don't live close by. I'd be standing around at your place all the time watching you turn inspiration into reality.

cobalt

That would be quite dangerous. I could only imagine the end result. There is no way you would be allowed to stand around and just watch.

Vancleef

What was the compression ratio of the first build? Any changes to it this go around? I'm searching the forums for more information on high compression (9-10:1) turbo builds to gain some insight on longevity and heat issues. I have plans to boost and looking towards 9.5:1, but may have to settle on 9:1.

Metal Guru

If I lived by you I'd be hanging out at your garage while contemplating new and novel ways of spending my retirement money on my Turbo.
Oh hell, you've already got me doing that and I live 600 miles away

cobalt

CR seems to be debatable on these engines. It was a stock N/A 993 engine which should be 11.3:1 per the spec book. There has been some controversy over what the compression ratio actually is on these engines. I believe the 964 engine is lower compression than the 993 and suffers from this more. I will be investigating this more as I tear down the next build which is a 964 engine but that will be a while after I finish this one.

We did measure the squish area and found the compression to be quite close to 11.3:1 but I had to clean the damage from the heads which spread to all of them but primarily the one was the big culprit requiring a replacement head which is not easy to come by. I did drop the compression ratio by swapping out the pistons. There are some things I don't plan to share until the engine is up and running but will say it is in the range you are considering. Sorry but a lot of time and math have gone into this and I want to be sure it is all correct and running before I comment on this. I will add that my recent 964 addition has the strongest "stock" engine I have ever driven. I spoke to the builder of the engine the other day and he said that the 964 engines are actually lower compression than the factory claims and are closer to 10.1 ratio and the reason the engine feels so strong is they played with it to achieve the factory 11.3:1 compression ratio. I will leave it at that for now. The 964 engine will be dyno tested once all this snow disappears but if I had to guess if he is correct in what he said that engine is probably seeing 275bhp and increased tq, not much different than the Cup Cars of the day. Makes me wonder what games Porsche played there as well.

So I was concerned with potential hot spots from the FOD. I polished out each of the cylinder heads removing anything I felt was suspect trying my best not to mess with the shape or CR. They all passed the finger nail test and I measured each one when done. The best I can tell they are all in spec. There are some artifacts left (this head was the worst) when done and had to carefully maintain the shape across all heads. I don't have any high spots so I believe I should be OK. Used a piece of lucite and syringe to fill each head and they all measured the same volume. So 🤞



I also polished out some of the roughness in the intake ports which were quite rough but didn't want to go to crazy. In order to use the GT3 Plenum I had to swap out the plastic 993 intakes to the larger RS versions. This is not a perfect solution but adequate for a boosted engine.



I can't seem to find the pictures of the intakes and the measurements but the RS versions are a few mm larger OD and ID which helps with the larger runners. If this were an N/A engine it would be matched with the ITB's.


You know that isn't true. You were already teetering on the edge, I just gave you that nudge

So my progress will slow these next few weeks. My surgery was postponed several times since November due to Covid concerns and it has set me back 10 years. So back to the drawing board and more tests and treatments to come. OH Joy. But nothing to be overly concerned about.

luv2race

Another fun to follow thread by Anthony.

cobalt

Good news. Just got word the second IC core will be here in a few weeks. So I will move onto the plumbing of the turbos for now. This is a two part process. One system for oiling the other for cooling.

I never finished off the exhaust which is mostly done. Like anything the first time always takes 3 times as long and in this case it is no exception. Trying to fit and make parts to fit isn't easy. Having the flow I wanted was also work. I ended up with the first half I called the boost bong. It reminds me of something.🤔

Maybe I can sell visual knock offs of these to pot smoking car guys and finance my build LOL.

I have to cut the pipe longer than I wanted it to then shape it to fit the radius of the larger pipe. If this gives us problems later we will revert back to dump piping it out but I prefer not to.








Getting the tail pipe length was a bit of work but for now this is where it stays. Maybe a change later but always easier to remove than add.



I like this picture as it shows you how much a wide body will gain you vs a narrow body for track width.



So the big dilemma on this is turbo drip tanks. Do I need them? I have seen cars with and without and then I see many with oversized tanks that hang down far too low. My B&B drip tank on my 94T is one I am not pleased with the design. So I searched into prefabbed tanks and then making them myself and of course the factory parts. I liked the designs used on the 996/997 TT's for my purposes but the question is will they fit properly.



So the price of the 996 tanks was worth giving them a shot. Once they arrived I saw the initial problem. The mating surfaces of the factory Borg warner turbos is larger than the ones I am using. Of course finding that info is not easy. So I decided to go ahead and modify the tanks to work. After milling the openings for the bolts I think we should be OK for them to fit. I need to verify that they won't leak oil but once this is done the pipe bending begins. We will be using 8 AN Stainless piping to return the oil to the case. After researching how Porsche handled the 993-997 turbo returns we have a plan to feed the oil back through one of the freeze plugs which is where the 993TT returns its's oil. There is also the issues of oil feeding back to the turbos causing smoking on startup we will be addressing. Hopefully this afternoon I will have some pictures of progress but getting started is always the hard part.

911Jetta

I was lucky to get a shop tour at Turbo Kraft last week, Chris showed us this set up.

Metal Guru

When I re-designed my exhaust, the GoingSuperFast drip tank I had was the low point, Even after I shortened the pipe from the flange to the tank proper.
When I considered eliminating it, the issue became worrying about where the 8 ounces of residual oil that empties from the supplu line on top of the engine backs up to.
My solution was to fabricate a new drip tank from 304 ss that was ovalized.



This one still retains the 8 oz capacity and doesn't scrape any driveways

cobalt

Funny that was pretty much what I removed. Initially the idea of a center exhaust was cool but has its drawbacks especially loading and unloading the car from the trailer. My exhaust is not perfect but whatever imbalance we have we can control through the ECU and speed sensors on the turbos. Turbo Kraft makes some nice stuff but I wanted a system uniquely my own and enjoying the process of making it work. The accumulators they use seem to be the same ones Dundon uses. I could have sourced those or similar but they wouldn't work for my design. The material I am using is also has much thicker walls.


Nice work Paul. I was considering building them but the 996 tanks were cheap enough and require some modifications more so on the right side. The nice thing is they tuck up tightly against the turbos and have a design that helps prevent oil from escaping out he vent port which will be vented up high anyhow.

Typical the parts arrived and they sent the wrong ones so I am a bit delayed again. Might need to spend some time at Pino's on the slick top project for a few days depending on what parts show up.

This is what I have so far. Not very productive but that is the beauty of being retired. LOL






We did start building the coolant tank for the turbo cooling system which will be mounted in the frunk.




Not much to look at yet needs welding and other bits added.

Metal Guru

Those drip tanks are really nice. Wish I would have known about those when I was going through my buy/make analysis (but there didn't seem to be anything to buy )

cobalt

So progress has been slow waiting on parts. Covid this and that seems to delay everything. Good news is the C2 slick top is nearly complete and ready for primer soon. No pictures on that front yet but soon.

So getting what we can done. I am working on the oil tanks and return lines. I did some research regarding the later twin turbo models and smoking on startup after sitting. The answer seems to be a kink or rise in the return line to help keep oil in the case from returning to the turbos while sitting. The issue is we don't want a situation that might shorten the life of the turbo bearings. The low spot in the case should create a siphon effect created by the oil pump that will help draw the oil from the tanks. This is where the 993 TT returns its oil through the A/C bracket. At this time it is still a rough mock up and might get changed I am waiting on a T to connect the lines to the engine. For now you can see the AN fitting in the case and where the two lines meet will be the T. I was concerned with having the oil lines or return point being higher than the turbos but after checking out some later 996/997TT's it appears that they return the oil through the right rear oil return tube opening which is not drilled out like the air-cooled cases on the water cooled engines. This is a higher point than the 993 and seems to work although they all smoke on startup from the straight lines installed by the factory.

These pictures seem to distort the lines placement. It was on wide angle so things seem a bit further away than they are. I wanted to keep the lines close enough to the engine so I can support them and they don't catch on anything but still be far enough away from the heat which isn' easy. The bends reach up to the oil return tubes and will see how they work and can easily be changed if needed.



The other project is the coolant system for the turbo's. It will be water based using water wetter. I am using an oil cooler from a tip trans to piggy back off the second oil cooler and the pump and reservoir will be mounted in the frunk. The tank will be able to handle 1 bar of pressure so I need to pressure test it for about 250PSI to be safe. The cap is designed to lift and vent any additional fluid if it exceeds 1 bar. At this time this is all I have while waiting on the rest of the parts for this part and the second I/C core is supposedly on its way so that can be done soon.

The tank will be powder coated black for looks.



I should be posting progress on the slick top thread soon.

Greg Wolfe

This is unreal. I want to be just like you when I grow up.

Mr. Wolfe

cobalt

LOL, thx