SMALL single turbo project, thoughts welcome! - Page 5

ZephTheChef · #61 11-16-2010, 05:35 PM

Quote:

Originally Posted by httrdd

Coming along well!

Yes, I've been neglecting my other projects and putting a lot of time into the SVX. The pre-turbo exhaust is actually all tacked up. I'm not going to post pics until I've got it all welded up and wrapped...I ran out of argon and haven't been back to fill my bottle, so I've had to do it with my MIG so it looks like a 5-year-old welded it and quite frankly I'm a bit embarrassed. I'm no master welder, and I've gotten pretty out of practice with my old mig. I've been spoiled with my TIG...cheap and made in China though it may be, it works great and is SOOO much more precise!

Can't beat the MIG if you've got big holes to fill though, lol...and I did have a few. Kind of messed up on my measurements on the merge and it came out a little funky...I didn't have the materials laying around to redo it, so it's going to have to do for now. It's not pretty outside, but the inside is actually pretty smooth. As far as piping, I opted for 2.5" from each manifold, merged them into a single 2.5" pipe into the turbo, and will be running a short length of 2.5" exiting the turbo due to space limitations, then transitioning to a 3" pipe and running that on back to where the main cat was bolted on, leaving the rear portion of the exhaust stock for now.

ZephTheChef · #62 11-16-2010, 08:42 PM

Ok, small update and a few pics. I made up some block-off plates for the valve-cover vents, as I obviously don't want to hook them up to the intake anymore since it's going to be pressurized. I used what I had laying around, will probably make some shiny ones out of stainless steel and polish them when I get a chance...but for now it's poly. I didn't spend much time on them, so don't hate, lol.

I also hollowed out the ****ty factory PCV valve and am installing my own beefy, high-flowing one inline, running it directly down to the crank breather near the rear of the engine. It should draw a pretty good vacuum on the crankcase and the vacuum will help evacuate the oil from the turbo. I'm in the process of sorting out how the vacuum lines are going to be run...it's a nightmare with all the stuff I'm eliminating.

Also, resized the pics to 640x480, so the thread won't look so weird.

Pics:

Passenger side block-off plate:

Driver's side block-off plate:

Hollowed out PCV valve (I'll probably drill the hole out a bit bigger as well):

New beefy check valve (cracks open at about 1psi, supposed to hold 150+psi the other direction):

oab_au · #63 11-16-2010, 10:00 PM

I think you might have a few problems with your PCV system. That valve is too small, to pass all the crankcase blow-by. You will have to vent to the turbo inlet.
You will need to limit the amount that is drawn in to the inlet track at idle, when the vacuum is high.

Harvey.

ZephTheChef · #64 11-17-2010, 12:39 AM

Quote:

Originally Posted by oab_au

I think you might have a few problems with your PCV system. That valve is too small, to pass all the crankcase blow-by. You will have to vent to the turbo inlet.
You will need to limit the amount that is drawn in to the inlet track at idle, when the vacuum is high.

Harvey.

Harvey, could you elaborate on your concerns? I understand the way the PCV system normally works, but that's in a system designed to run at atmospheric pressure. The goal here is to create and maintain a strong crankcase vacuum. I have no desire, and probably no need to limit this at idle, as there will be no vacuum leak except right at startup...and the single cubic foot of air in the crankcase/valve covers that I'm sucking in is not going to come even remotely close to throwing off my air metering...the exception being if I don't have an airtight crankcase, in which case that's something that needs fixing anyway. If all my seals are in good shape and the engine is airtight, the volume of air that is sucked out of the crankcase on startup is negligible.

I've never used this particular check valve before, but it's definitely the highest flowing one I've ever used, I'm not sure what you mean by it being too small to pass all the blow-by. I'd argue strongly to the contrary. The blow-by, in my experience, is pretty much negligible when you're making vacuum...under boost I can't say I've ever really done the math on that. This is always how I've run the system on all my vehicles...put vacuum to the crankcase, block off any unused ports, and go on about my business. I don't even use a check valve on naturally aspirated vehicles.

Typically, vacuum builds instantly upon startup, and if all your seals are in good shape, all is well. If not, you'll have a vacuum leak, which needs to be addressed anyway because it was likely present as an oil leak anyway. I'm curious as to whether or not you're talking based on experience or hearsay/assumption...I've probably had it set up this way on a few dozen vehicles, both turbo and NA, with no problems...however, I'm not the racing type. I'm rarely on the throttle for more than a few seconds at a time. The SVX will probably see the drag strip though, so I guess I should go about it differently.

The only way I could see this being an issue is under sustained boost, when the valve would obviously be closed. Perhaps during a 1/4 mile run for example. If it becomes a problem, I can throw the valve cover breathers back on, stick cheaper check valves on there (since they'll never see boost, just vacuum), and that way I'd have a vent to atmosphere any time there's positive pressure in the crankcase, but still be able to build and hold vacuum otherwise. Alternately I could install a large vacuum reservoir, to allow for more blow-by before hitting positive pressure in the crankcase, or to take that a step further, I could install an electric vacuum pump.

Your post got me curious about the blow-by I should expect on boost, so I started digging around for info on the subject. Per an old engine builder, blow-by on a healthy engine should be expected to be the horsepower it's making divided by 50, in cubic feet per minute. At 49,000 miles, I see no reason my engine shouldn't fit into the "healthy" category as far as ring sealing goes. I calculate expected blow-by on a healthy engine, making 380 HP (which would be the maximum of what this turbo can put out) to be 7.6 cfm, or about 1.5 cubic feet during an entire 1/4 mile run for a car at that power level. Of course you're not making the 380 the entire run, so we'll call it an average of 300 which gives us 1.25 cubic foot. I'd guesstimate that the crankcase is what...half a cubic foot? If that's the case, I'd need about a 5 gallon vacuum reservoir to end up at atmospheric pressure at the end of a run, lol...or a $100 vacuum pump and a power inverter. Not completely out of the question, but a little bit of a ridiculous solution to a simple problem.

So those ideas are out the window in favor of installing a check valve between one of the valve cover vents and atmosphere. Best of both worlds. Thanks for bringing it up. I'd never really sat down and done the math on what to expect, but it looks like in a 1/4 mile run, I could end up with some 20 psi in my crankcase if I were to block everything off. That wouldn't be the end of the world, but I'd rather not have that happen.

oab_au · #65 11-17-2010, 03:52 PM

Well mate you only have to look at the engine std. It has three crank case vents to the inlet delivery pipe, and still builds enough blow-by pressure to push the dipstick up. Add boost to that,,,,,,,,

Don't want to be a dower,

but I can't see you maintain a vacuum in the crank case, even without blow-by. Any sort of negative pressure will suck air in through the oil seals, which will act as one-way valves.

I can see that you want to do this your own way, but a single turbo on E85 has been done before by Phil "Phast SVX", so you could check what he has done, to save you some work.

Cheers, Harvey.

ZephTheChef · #66 11-17-2010, 04:26 PM

Quote:

Originally Posted by oab_au

Well mate you only have to look at the engine std. It has three crank case vents to the inlet delivery pipe, and still builds enough blow-by pressure to push the dipstick up. Add boost to that,,,,,,,,

Don't want to be a dower,

but I can't see you maintain a vacuum in the crank case, even without blow-by. Any sort of negative pressure will suck air in through the oil seals, which will act as one-way valves.

I can see that you want to do this your own way, but a single turbo on E85 has been done before by Phil "Phast SVX", so you could check what he has done, to save you some work.

Cheers, Harvey.

I don't know where you're getting that from...I'm telling you I've run it this way on numerous cars and you can't hardly pull the oil cap off on some of them the vacuum is so strong at idle. If your seals are in good shape, vacuum will not leak past them. It takes my daily driver 3000GT some 15 seconds or so to equalize after the car is shut off (as evidenced by the nice whooshing sound you get if you pull the dipstick).

I have a very hard time envisioning there being enough blow-by to blow the dipstick with open valve cover vents. In any situation. The only cars I've ever had do that were my supercharged Z28, which just had one very small valve cover breather, and my VR-4, when my PCV valve failed and put intake boost into the crankcase.

I'm telling you it works. It's not something I'm going to argue any further, because I've done it so many times there's no question about it. It's a great way to find and fix oil leaks too...if your crankcase doesn't hold vacuum then you have some bad seals. My buddy's 280Z for example squeaks like hell if you hook vacuum to the crankcase. He's got seal leaking badly enough it causes the car to whistle/squeak if you do this.

oab_au · #67 11-17-2010, 04:29 PM

OK no problem.

We'll see how it goes.

Harvey.

ZephTheChef · #68 11-17-2010, 04:36 PM

Again, I do appreciate you bringing it up, because it did get me to do the math and I now realize that during a 1/4 mile run I would in fact see positive crankcase pressure if I don't leave an atmospheric vent available (with check valve so I can still build vacuum off boost). So kudos for bringing that to my attention

ZephTheChef · #69 11-18-2010, 11:11 PM

Small update, finally got to play around with the chips LAN sent me. I spent several hours scratching my head before I finally figured out the whole even/odd thing and found a way to combine them, but it's been smooth sailing after that. I'm happy to say, the timing numbers look almost exactly like the ones I had punched into my .bin. The fuel maps are still too lean for my tastes, so I'll be taking care of that before it goes into the car, but otherwise I'm very pleased.

I was glad to see my timing numbers were so similar to his, I was afraid I might have gotten too aggressive with them, but seeing that they were nearly identical was a big confidence boost. If you can run that much advance on 91 octane, I should have no problem on E85...I may even throw a little more at it.

Tomorrow night I'm going to try and get the car back on the lift and hopefully finish tacking up the exhaust. I'm planning on using my spare turbine housing (with a block off plate to cover the gaping hole where the CHRA would go) so that I can drive it around prior to getting the rest of the turbo stuff done and not wake the neighbors

I'm excited to get the fuel stuff and exhaust finished up and try out my new tune. I think I'll be loading a stock tune in to be switchable to, so that I can easily compare the difference. I'll be out of town for about a week starting on Wed...for Thanksgiving, so I won't get anything done next weekend. I've really gotten motivated on this project though, and I'd really like to be spoolin' by Christmas

NeedForSpeed · #70 11-19-2010, 12:34 AM

Great work, great progress, very interesting

Pure_Insanity8 · #71 11-19-2010, 07:44 PM

Hadn't noticed what you will do to overcome the MAF issue. Will you be replacing it with one that will work at the air flow levels you're shooting for?

ZephTheChef · #72 11-19-2010, 08:17 PM

Quote:

Originally Posted by Pure_Insanity8

Hadn't noticed what you will do to overcome the MAF issue. Will you be replacing it with one that will work at the air flow levels you're shooting for?

I have the scaling for both the Z32 and Q45 MAF. There's been much debate as to which will handle more power, but I don't think I'll even be close to maxing out either...so I'll probably go with whichever I can pick up cheaper.

ZephTheChef · #73 11-19-2010, 08:32 PM

I've got the pre-turbo exhaust entirely tacked up, and am working on the piping from the turbo to the stock mufflers now. Hopefully I'll be finished tacking everything by tomorrow night. From that point I'll take it all off, weld it up, and go to town with my techline ceramic coating, to be topped with some exhaust wrap, and topcoated with the high-heat sealant. It should look nice, keep the heat out of the bay, and sign about a 2-4 year death warrant on all my piping (although I'm hoping it will hold up a lot better with the techline coating applied first)

Gotta love how destructive wrapping your pipes is, but totally worth it in my opinion.

Myxalplyx · #74 11-19-2010, 10:15 PM

If....no I'm sorry....WHEN this is successful, what do you plan on doing with all the turbo parts you make? Sell? Dibs?

ZephTheChef · #75 11-20-2010, 01:55 PM

Quote:

Originally Posted by Myxalplyx

If....no I'm sorry....WHEN this is successful, what do you plan on doing with all the turbo parts you make? Sell? Dibs?

IF this goes together smoothly, and I have confidence that I can replicate and improve upon it with a reasonable degree of quality, in a timeframe that would make it reasonably priced, then I'd absolutely consider making kits for interested people. They won't be 100% bolt-on, but very close, judging from what mine is looking like so far...the modifications to the car for installation will be fairly minimal. I'd say it's going to be something that could be put on pretty easily in a weekend, or one long day.

If you want to talk specifics, feel free to PM me and I can give you a rundown of what I think (from my experience so far) it would cost to build you a "kit". Obviously nothing's a sure thing until I get it up and running, but it never hurts to plan ahead a little. I've been moving on this way faster than I anticipated, and have an optimistic goal of being done before the end of the year.