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Draw through junkyard turbo installed and running under $100

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They said it could not be done.  they said old rajay turbos are junk.  Every Datsun and Nissan forum I found was full of naysayers.  They always say there is a better way and not to waste my time.  Well, I guess they have $ to waste.  Not me.


   What I do have is a genuine dump find, rebuilt in 98 and sitting  who knows where since, Rajay, carbon seal turbo.  I also have a shop with fab tools, so I whipped up a header, flanges, mounts, intake plates, and piping, an oiling system complete with large cooler, 3" exhaust, carb manifold for intake on turbo, and a gauge panel.  I bought a gasket set, new thermostat, some fuel line, gasket material, and a few bolts.  Everything else was made in house from scrap, junk, old parts, old cars, hardware drawers ect.


I stripped my old beater 1982 Datsun 720 4x4 with the z22 engine of all emissions bs.  Installed all the stuff I made, and after a cranking session to bring up the oil pressure in the turbo, It fired right to life.


I am using the stock carb on a homemade plenum with gets sucked through the turbo.  Intake runner is short with one clamp connection.  Turbo is mounted above the valve cover and carb sticks up very high.  Got 10lbs of boost, my first test run.  Truck went faster than it ever has before.  Fun to make. fun to drive, and cost less than a night out.  Also being in rural bush Alaska I didn't have many other choices.  Suck it, to those who made nothing but negative commented in the various threads, but have never built a draw through turbo setup.  Some of us enjoy tinkering with old, outdated, cheap technology.  I encourage others who have been discouraged to try as well.  If it's good enough for use on airplanes, then why is everyone so scared.  If you've got the parts, no money, an old beater test mule, and the time, why not?  Anyone can go spend lots of $ on a turbo kit.  Takes an old school person  with talent, and skill, or just pure dilligence to make this work.


Pics and video to come.

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I think they probably mentioned that reliably you can run them at about 6-8 PSI without too much trouble. By 'large cooler' you mean an oil cooler? excellent idea. Do the old Rayjay turbos have a waste gate? or some boost control on them? Without this you really have a time bomb. IIRC the old ones relied on exhaust back pressure to limit boost? and often they could run away with themselves. Are you running cooler plugs? Interested in hearing and seeing more.


I've always said the Z series engines were a perfect candidate for a turbo. They have cross flow heads with lots of room on the exhaust side for the turbo and manifold keeping the heat away from the carb and lots of room between for an inter cooler. Dual plugs for decreased ignition timing. 'Hemi' combustion chambers. 


Welcome to Ratsun. Don't forget the pictures..... http://community.ratsun.net/topic/54932-photobucket-ratsun/


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 Suck it those who commented in the various threads, but have never built a draw through turbo setup. 



i agree, SUCK IT! That is the one thing i dislike the most about forums, all the people that say you can't do something.

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Still tuning, fixing oil drips, ect.  I used a large chambered tranny cooler I had laying around for the oil cooler.  Also made a inline chamber This morning I made a restrictor for the turbo oil feed line.  Seems my oil drain line is too small and also needs less angle where it drains into the block.  I haven't changed plugs, or done anything other than messing with the carb.  My seconderies don't seems to opening properly or early enough causing a lean condition that won't let the turbo spool, until top rpm range.  


I used zip ties to try and bump them open once the primary is half open.  That and retarding the timing more, seemed to produce the best speed test runs yet with pressure starting to build at 3000 rpm and hitting 15lbs by redline.  I also added a gallon of gas with mothballs in it to my tank. 


My dipstick blows out every time I hit 7lbs or more.  Engine is old, has blowby, lower compression due to worn rings, ect. 


Anyone ever drill out the plug and use the mixture screw on the stock hitachi carb?  Thinking about diy washer fluid injection with a NOS nozzle


I live in the middle  of nowhere and summit won't even mail stuff to me.  Prefer to spend time making it work rather than throwing money at new/more/better parts.


No egt gauge yet.  Got one from Amazon coming.  I have a analog water temp gauge, another for oil temp pre cooler, a vacuum/boost gauge, oil pressure, and volts.


Truck only sees short trips, as we only have 14 miles of road here.  Used mostly to blast back and forth to the dump, or short beach trips.  Truck is very well used, abused, welded on, rusted to an extreme level as it was swamped  in salt water.  I got it out of a junk yard, and fixed it up in the welding shop with pieces from the dump, and other junkers.  drove it for 14 years, and used most body parts from a doner, to fix it up again.  Painted it black with a roller.


How do I upload pics and vids?  Should I just try photobucket or whatever the picture posting website is called?

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Of course you can boost above 10 PSI. If you stay around 7 PSI this will last much longer than if you constantly run it to 15. It's going to require great care to prevent detonation which will punch holes in your pistons. Detonation is, in simple terms, the heat generated by compression igniting the fuel/air before it is supposed to. You have hyper eutectic pistons. Basically about 17% silicon (glass) they re extremely brittle. Factory turbos with these rarely boost above 7-9 PSI even with advance timing control these pistons won't last.



All is not lost though. You can reduce detonation by being proactive in reducing heat before it becomes a problem. Here you are on the right track with an oil cooler. Oil gets to the hottest parts of an engine. A good supply of cool oil helps. Running very rich jet on the secondary is a good thing, as the extra gas helps cool by evaporation. Water/alcohol injection is another good way to drop air temps from cooling by evaporation. Windshield washer won't have the pressure to work with a NOS nozzle. Just direct the spray into the turbo... think of it as a kitchen blender. Air should always be drawn from in front of the rad... again you want cool air not warm rad air. Everything should be directed towards reducing, removing heat.  



A disadvantage of a draw through system is that precludes the use of an inter cooler which goes a long way towards lowering the air temperature if the incoming air.


To reduce pre ignition a higher octane gas can be used. Octane makes it harder for fuel to ignite. The tip of a spark plug can begin to glow red hot under boost. This can become an ignition source during compression. A cooler range plug will run cooler.

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So in my past experience with a washer pump setup, I had very inconsistent results with no tip, and not much better luck with the tips I made.   1991 Subaru.  What about a different type of available nozzle, like for water injection.  Should this nozzle be in the intake pipe/post turbo, as apposed to being sent through the turbo inlet with the air and fuel


I was also thinking today of just adding another stock hitachi  carb that I have to the setup.  Easy to fab a plenum, and just use the vac secondaries on the 2nd carb. cheap and easy way to add fuel on demand. I've got some other extra carb ideas as well.  Need to install a vac line to my carb plenum/turbo intake first. Should have drilled those extra guage holes in my dash mounted alum panel after all.


Also going to fab a intake restrictor for the turbo.  Poor mans way of limiting boost.  Intake air is only 6" or so behind the rad, but 12" above it.  No hood yet, as it will have to be heavily modified.  Should I try a smaller turbo exhaust pipe as well.  very easy for me as I have a muffler tubing bender, and different sizes of tubing.  My thee inch tubing is very old and did not bend so well.  It likes to try and kink if it isn't fresh.  Lot's of 2&1/2" and smaller tubing on hand.  So far it is a straight pipe that goes through the pass fender. 


Carb plenum icing is already an issue.  develops fast as you can see the frost on the plenum while driving. Luckily I have a stock wet intake, but may have to add a water jacket or just outer piping to the  plenum


I have a couple 14" wheels that fit this truck, and I'm going to try and find some tires and mount them on the rear to  in effect, lower the gear ratio.  It might look  a little funky, but it will save my matched set from burnout abuse.


Somewhere I saw a air fuel mixture guage mentioned for like $30. It was an electronic one with a series of 9 lights.   Where would I plumb this or a different air fuel ratio guage in.  At the intake manifold, or the turbo intake , or the carb plenum.


I will look at getting a set of colder plugs on amazon.  Will take awhile to get here.


question about my distributor.  It seems to be all electronic as far as mechanical advance goes.  My research seems to say limit the mechanical advance mechanism. Seems to me this will not work in the long run.  Any thoughts?  Is there a dist from a different Datsun engine that will fit my z22.  I have a 1200 in an old parts pickup I could raid.  Dist from any other engine? 


Any ideas on Pics and video uploading.  Can I attach one or drag copy/paste it to this message

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Just use the squirters from the windshield or similar before the turbo. The turbo will homogenize the spray. As this is a set amount and the engine speed and demand varies, you may want more than one tipping in like a secondary.


Easier to just get a larger 2bbl that flows more air to begin with. Be sure to run super rich secondaries.


This is the problem with the old Rayjay. I don't believe they have a waste gate to regulate the boost. The more power you make the more boost, more power more boost.... positive reinforcement and runaway boost. Newer ones divert exhaust around the turbo when it gets to a preset limit. 


It's not the rim size but the tire diameter. A smaller diameter will raise the ratio effectively. This will bring the boost on sooner and the tires will spin easier.


AFR gauge will need an O2 sensor that will likely cost more than $30 itself. A good enough one is a couple of hundred and will show when dangerously lean when boosting. Lean when boosting only takes a second to hole a piston. This is why to run a rich secondary.


Just mentioned cooler plugs if needed. Plugs need to be hot to be self cleaning but may be too hot for boosting, it depends. If you are chasing a detonation problem it may be the plugs are too warm.


There are three timing functions. Static.. this is what you dial in with a light and it does not change. Vacuum advance.... only advances at part throttle when there is vacuum and not during boost. Mechanical... designed into the distributor and increases strictly by RPM. Static and mechanical are the only two to consider. They add together to give total advance. To limit the total advance you can reduce the static timing slightly. This will work all the time not just during boost and at part throttle the engine will be sluggish. There are adjustable timing controllers out there but expensive. They electronically dial back the timing in relation to boost to reduce the chance of pre ignition/detonation.

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No wastegate on this rajay.   You can limit the boost with a turbo intake restrictor.  I will be trying this route.  Also going to reduce the exhaust  outlet pipe dia.


Bigger two barrel is not an option unless I happen to find a serviceable one at the dump today.


$30 for a O2 sensor and $30 for a fuel/air guage on Amazon seems reasonable. 


Seems my Mechanical advance curve is electronically set.  Is there another dist I can scrounge up that has the breaker plates inside.  I can modify those to limit advance at high rpm while still keeping it advanced enough at low rpm to keep it from bogging, and or acting sluggish.


The tire dia on my 14" rims is much less than any 15" tire I will be able to find. 


You must remember, this is a junkyard/ spare or scrounged parts build.  Plus there is no tire store, no parts store, no hot rod shop, no nothing here.  Buying and ordering parts is mostly not even an option.  Plus I don't have time to wait a month or more for shit to arrive.


Do you think washer fluid injection before the turbo will create turbo lag?  Seems to me it will, but might be negligible, or will create enough engine power to overcome any lag the turbo sees from ingesting the washer fluid.  Any ideas on nozzles.    Maybe a small slide carb that is fed washer fluid exclusively and set to come on at partial throttle. 


I am not scared to try new things, think outside the box, and make other people junk make xtra hp for me.


My computer ate my videos last night.  Can't find them anywhere, so will have to take more.  Got all my pics though.

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Restricting the intake or exhaust will work I guess but it's restrictive at all RPMs and power will also be affected at all RPM. It really needs to be self adjusting only when you get to the boost level you want. Maybe a valve in the exhaust pipe or between carb and turbo and a pressure operated servo run off the intake pressure. When pressure nears the set amount the valve begins to close choking it off? Again, not the best way. You really need a self actuating waste gate. 


Mechanical advance is.... mechanical. There are no electronics involved. You can add stiffer springs to delay or limit the advance but it will do this weather you are boosting or not and like reducing the static advance will lower power across the board. Again you need something that only acts when you are boosting.


I meant the a 14" tire is not always larger than a 15", it depends on the tire on it.


Washer fluid is only being used when well into the boost range and to reduce combustion temperatures that could lead to detonation. If too much is used it will cool too much and power will drop. It won't cause any lag and power loss should be minimal and only enough to stop detonation.   

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Upload pictures to photobucket, click on picture once it's uploaded, next to the picture will be a few little icons, click the one that resembles chain links and 4 different "codes" will pop up that you can copy and paste, copy the one titled "IMG" and paste it into your post here on Ratsun. It will look like a code until you post it, then it will show the picture.

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Concerning my dist. There are no mechanical plates with springs. Just the black box inside. R u picking up what I'm putting down


I sure am. Under the 'black box' is the mechanical advance.









As RPMs increases, the weights are thrown outwards by centrifugal force. Both weights have a pin sitting in a slot on the plate in the above picture. As it moves outwards it twists the shaft clockwie advancing the timing


At  rest...



At full advance...




R u picking up what I'm putting down???


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Awesome, thanks for the pics.  I'm down like a clown Charlie Brown.  I can limit that for sure.   Thanks for the help.   Much appreciated.  Still working on pics.  My internet is totally fuc$#% up so after 3 tries to load some pics to photobucket, I gave up and went back to work.  Will try again later today. 


On a side note.  I took one little test drive yesterday with air intake restrictor/stock air cleaner. I left the hubs out and shifted the transfer case into low range.  Best performance yet, without overboosting. 


I will try and source parts for my washer fluid injection today.

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Makes me want to weld up a log manifold and throw on one of my Mitsubishi turbos just for kicks. Car is runnin ridiculously rich since I moved anyway. Definitely in for some pics though.

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I know there are plenty of draw threw turbos out there, but isn't there a danger of the fuel penetrating the bearing seals and toasting the turbo? 

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No but on a draw through set up when the throttle is closed suddenly there is a tremendous vacuum generated between turbo and throttle plate. This will suck oil past the compressor seal unless it's a newer carbon seal. 

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