TURBO Q & A FORUM

[spoolinitup33]

I'm not questioning the engineers, I was just wanting to know if running too much oil would be a problem because all of the fittings I have found that I was going to use don't have any oil restrictors. I guess I can call atpturbo and ask them about it after the holidays.

[goichi1]

I think I bought my lines from one of the sr20 stores on line, they were about $100 for the set, really easy to install, there was the water lines and the oil line, about the easiest thing to install in my whole build!! I forgot the name of the company that makes them....seems like it was CP performance or something like that....but really can't remember...

[spoolinitup33]

I think I bought my lines from one of the sr20 stores on line, they were about $100 for the set, really easy to install, there was the water lines and the oil line, about the easiest thing to install in my whole build!! I forgot the name of the company that makes them....seems like it was CP performance or something like that....but really can't remember...

I considered buying a set like you're talking about, I've seen them on some website before. But I think those are just for the stock turbo and stock location aren't they?

[Byron510]

Regarding too much oil...

It's unlikely you'll get too much oil flow - but too much oil pressure in the turbocharger can cause problems. Excessive oil pressure will cause too much axial trust on the turbo – in a direction that the turbocharger wasn’t designed to handle. The way the turbocharger is designed, the axial thrust generated by the operation if the turbocharger under boost is quite high - hence the need for the axial bearing engineered into the turbocharger. This takes load in one direction (usually towards the compressor side, but this varies with the different turbocharger designs). Now you do have an aux bearing that takes the axial load in the opposite direction. This is often of a much smaller design, and depending on the turbo, it may use the fwd face of the compressor side radial bearing (there's usually two radial bearings - compressor side and turbine side) as the aux. axial face. Now this aux. bearing isn't designed to take a lot of load, since it's only there to counteract oil pressure related axial force when the turbo isn't under boost conditions, which is damn near 98% of your running time, unless you really load the thing all the time - unlikely for most of us street car types (different for a guy in a truck hauling a load down the hwy - whole different ball game). Anyways, my point is that excessive oil pressure puts undue strain and wear on the aux bearing surfaces and can cause premature turbo failure over it's lifetime.
I see this at work in our ABB turbos from time to time, usually related to a mechanic who forgets to install the oil restrictor on the turbocharger oil feed line - especially noteworthy on the big Caterpillar diesel generators, but the theory is still the same. The manufacturer of the turbo will spec the amount of oil pressure recommended for optimum operation - it's back to the engineers. The turbo was designed to run under specific guidelines.
Just FYI

Byron

[bertvorgon]

rats, so does that mean that my riding mechanic and his "doink,doink" oil can, are not going to cut it any more?

[spoolinitup33]

Well I guess I can just use the stock banjo fitting that came on the SR engine, and then use this banjo: http://www.atpturbo.com/Merchant2/merch ... TP-FTG-018

[L24 510]

Yeah! I finally got thew the 19 pages of thread and get to post my questions that have not been answered yet. I have always been interested in turbos and want to build a draw threw turbo set up. I learned heaps of information from reading this but still need to go get a good turbo book, that ill do tomorrow. So here's my plan I want to build a LZ22 (L20 block Z22 crank) With ported u67 head. This is in a street car and i guess i want to get about 7lbs of boost. My goal is about 175 power. what compression is recomended 8:1 I plan to fab all the piping my self as to make it compact and custom. But im wondering what is the reason that all turbos i see are mounted horizontally In my setup I want to mount it vertically with the turbine outlet facing down so i can put a carb right on top of the inlet. Is this possible or is there some reason because oil flow that a newb like me doesnt know Also from most of what i read i get the feeling that people are using weber style carbs. I was thinking i could just get a 300-400 CFM holley and plop it on top of the turbo Then jetting and such are easy as pie because for a holly there is a hole mess of different parts. I look forward to your responses and cant wait to start building this thing.
Scott

[bertvorgon]

Not sure about orientation of the turbo, most are designed to drain straight down, relying on gravity. Plus, not sure about thrust issues with the turbo bearing. Byron/Rob will likely answer this. Then there is the reality of trying to match up to the exhaust system!

Compression...fuel octane will determine to an extent, plus timing, plus jetting, etc, as to what would be best. 8:1 would be ok, but, again, read above, as your fuel down there is only 91 octane for premium I beleive. It would be a good compromise. Higher compression gives you snappier, low end performance, before boost builds ( which is also determined by the turbine housing size) Lower compression will make it really "soggy" when you get on the throttle. The original kit that I run, used the stock compression of the L-16 at 8-8.5 :1. It was not bad, but then we had 98 octane fuel as our premium gas, which let the boost build quite fast, at low speed and RPM (load), so detonation was not a problem.

Regarding a suck through application. I had some experience/exposure to this type during the 70's. Crown made a kit for the 510. The biggest issues, which are determined by HOW FAR AWAY from the turbo the carb is mounted, is, cold starting. Fuel tends to "drop out" with long runs from the carb. I can se why you would want to mount the turbo right ON the inlet, but, packaging will be tough with trying to get the exhaust oriented. I can remember guys cranking and cranking, trying to get their cars started with the crown kit. Also, as the WHOLE systen is loaded with fuel/vapour, a backfire can be an interesting thing!!! Not that that will happen....but, everything better be spot on.

The type of turbo is important also, as the turbo will be under engine vacuum, which requires a seal on the turbo, to keep oil from being sucked into the intake system.

A fellow here used a Holley 500 CFM 2 barrel for his suck through, on the legendary "Killer" Datsun 1200, with the Dodge Colt motor in it.

You should PLAN right off the bat, to get a wide band air fuel monitor. No matter what route you take, it will save you tons of time and possible grief, if you know how the A/F is doing. beleive me, I have been there!

Some thoughts at any rate

[510rob]

In short, you can't mount automotive turbos vertically because they are not designed to run that way. It's an interesting idea though. One of the old Aerochargers might be able to run vertically, but then you are using some obscure old piece of hardware with no support.

People have been using the Weber 32/36 DGV carbs because they have readily available jets, and they have a mechanical secondary - you can jet the primary circuit on the slightly lean side to keep things crisp, then jet the secondary circuit to run nice and fat when you floor it and the boost comes up. The only trick is if you bring the rpms up while running on the primary (low throttle angle) and if your particular turbocharger starts to get to it's boost threshold, the engine will start to go lean and get cantankerous pretty quickly. It's all happening at low thermal/throttle load, so the total energy going through the motor at that point is lowish, but still, it will run like a sack of rusty nails until you get into the throttle to open the secondary butterfly, and pour some fuel into the fire - ZOOM! (no woosh, because that already happened when you brought the RPMs up!)

If the Holley 5200 is available, and you can get the right jets, it will probably work just as well (or better because it flows more air!).

X2 on the wideband - you can tune an engine without one, but damn would that ever be a waste of time compared to how fast the job can go when you add a wideband sensor system! They have their own quirks, and are not perfect, but perfect is only a concept on paper and in imaginations - they are practical.

Get a copy of Hugh MacInnes' book - Turbocharging - it is a great turbo reference, full of theory and data. It is also full of carburetor-related turbo information.

[Byron510]

There is one other option. Back in the 70's and early 80’s, many guys faced with packaging problems with their turbo systems used SU carb(s) on their applications. I've seen it in Hondas, 510’s Subaru Brats, Celica’s and 240Z’s. I can't tell you how well they worked, or what type of air flow these set ups were using – I’ve just seen them. You can buy SU type carbs, in all their simplicity, up to 2" bore size, which is pretty damn good.
I know there was a kit made for the 240Z in the 70's that used one of the two standard OEM N/A SU carbs - apparently it was enough for a street turbo application on the Z car. You couldn't get much simpler and much smaller package.

Byron

[L24 510]

Ok good to know, I thought a little about using SU's. I have the dual 1600 SU set up on my stock L20. I could just use those with a different intake to adapt to the turbo Thanks for the info guys, Im gonna go look for that that book.

[McShagger510]

The first setup was a blow through with a Weber 32/36 in a pressure box. A pain to tune to say the least - bolts, resiliconing the box, etc. It took a bit to get it all sorted (big thanks to Keith for all the old notes!) but once it was going good it dynoed 185hp at the wheels. Sorting out the fuel pressure delivery is a tricky one too. Carbs like to run at 3.5 psi so when you start ramming in more air you need that much more fuel. Example:10lbs boost will need 13.5psi fuel. The carb will need a plastic float(s), stronger needle & seat and jets, lots of jets. You'll be screwing around with this for a while. Retarding the timing under boost is another problem. I used a MSD Boost Timing Master to tie into the electronic dist.
After just recently installing fuel injection to my turbo L engine, I'd recommend that instead!

Good Luck,
James

[L24 510]

ultimately i would like do do a fuel injection set but i dont do well with computers/electronics. What is a general price for setting up a complete injection system? I found one on ebay but it still needs the computer and injectors.

http://cgi.ebay.com/ebaymotors/Datsun-5 ... 250wt_1052

Back to the engine build. What are you guys doing for forged pistons I have made a few calls and looked at countless piston makers. It seems that all the off the shelf pistons for a sr20 or vg30 have a 22mm pin bore and the stock rods I am going to use have a 21mm bore. Top End performance said they don not recommend boring out the rod. What rod piston combo do you guys recommend for a turbo LZ22 Id like to stay away from the aftermarket rods because they are WAY too much and i probably don't need them for a street motor. Ive been using that ozdat to calculate combos for me and works out good. I found that the sr20 and vg30 pistons have the necessary requirements except pin bore. A KA piston might work, but in my opinion a KA piston with a 89mm bore is to big to go into a L20 block. although it does have the correct pin dia. But the dish volume isnt exactly what I want.

I think i found the set up I want, or at least the concept.
http://turbofire.no.sapo.pt/images/DRAW ... O_CARB.jpg
http://www.youtube.com/watch?v=lXf_VG2C ... re=related
Now does any one have a stock header they want to sell Would you guys happen to have any pics of the setups you run or used to run? Im interested in header design.

[hang_510]

What are you guys doing for forged pistons

a KA piston with a 89mm bore is to big to go into a L20 block.

i have those Arias pistons @ 88mm, youd need to machine them. id guess that the stock rods are sufficient when modded for full floating pins.

[maldat]

1) Are there turbo exhaust manifolds available for L-series engines?

yes factory item from a LD20T engine..fitted into Largo Vans in Japan (c20 JDM) .

Yes they bolt onto the petrol head with no problem...
I've also checked out bolting on to head with
# 1 factory inlet mani
#2 single side draft mani
#3 twin side draft mani
#4 L1600SSS inlet mani
#5 L18 efi inlet mani

all above bolt on with turbo mani no problems.

But factory turbo cast outlet mani, turbo sitts at #4 cly, for street use its fine , but for race it would be no good as it would suck out #4 and #3 before it sucked out #1 and #2 ..

Z18 turbo manis are the same turbo sits at #4 and those manis crack thew the middle..between number #2 and #3..


factory oil line for the turbo comes from the tee unit fitted at the oil sender.