NA to turbo conversion - questions and answers...

[Clifton]

Can I use stock NA injectors with a longer pulsewidth? I bought some NA injectors thinking they were turbo, silly colorblindness - hey they looked brown to me!

 

No on the n/a inj. You will run out of duty cycle real fast. I would get 380 cc/min for lower boost. You will come close to maxing a 450cc inj on pump gas with a decent turbo and 20 psi.

[mikeatrpi]

Derek (Challenger) hooked me up with a good price on some genuine turbo injectors. Also thanks to Vinh for a great deal on the bulk of my turbo swap parts. Thanks guys!

 

Here's the last couple weekends' progress. I did some electrolytic rust conversion & painting.

 

[mikeatrpi]

My clutch literally broke about two weeks ago, so turbo progress has stalled. As long as the car is half apart though, I'm going to tap the oil pan for the turbo drain and install a new steering rack. I'll be back with pictures of that ordeal soon enough.

[datman]

I think the stock dished pistons on the P90 head get like what, 7.4-1? So with flat-top pistons and a 2mm headgasket that would put you around 8-1?

 

So with the higher CR you wouldn't be able to run quite as much boost, you'd get more low rpm torque IIRC.

 

Therefore, and correct me if I'm wrong, because of the lower boost and less timing to avoid knock the engine wouldn't have as much peak horsepower, but with the higher CR would have more low end torque aka more streetability.

 

I had .5mm over size pistons, I did measure everything including the gasket and it worked out at 8.35:1. I'm running 14psi now with no knock and 18deg of timing...my FMIC works very well as my IAT doesn't move more than a few deg....on an 20deg day my temps are around 26deg. The car is very very responsive and has more power than you can put down on the road...looking at the logs I rarely use more than 50% throttle.

[mikeatrpi]

Another update. I upgraded the clutch and installed a 240mm setup from a 2+2. Its a "Spec" clutch, street disc, with a 240mm flywheel that was machined. I installed a Nissan throwout bearing onto a collar from a 2+2 (which is shorter than my NA collar). While I was in there, I replaced the rear main, some trans seals, the steering rack and the oil pan gasket. I wanted to rebuild the rack till I saw the FSM instructions...!!

 

For the oil pan, I drilled a hole in the side (10.5 inches from the back, about 1 inch down) and welded on a 1/2" NPT fitting. Actually its a pipe coupler cut in half. I have a plug in it now, but I can back it out and install a heater hose fitting when I do the turbo swap.

 

Pics - the hoist

 

Measuring where the drain should go on my parts car.

 

Drain fitting in the side of the pan

 

Little paint...

 

Rack and pan installed

 

The oil pan fittings. The coupler is sawed in half and the shinny fitting on the left goes in when I put in the turbo. I didn't photo the plug, but its just a 1/2" NPT plug with a female hex recess in the head.

 

The clutch

[mikeatrpi]

Here is the intake manifold ready to run. Its just the NA manifold cleaned up, sandblasted, and coated with PPG epoxy primer and MC161 clear coat. That's right, no paint. The details - bolts, block off plates, springs, etc are all painted silver.

 

 

I blocked off the EGR, cold start injector, idle air controller on the bottom of the manifold, and an air fitting on the throttle body. I also plugged the hole that the PCV used to occupy. Instead, I'm going to route it to a spare fitting on my throttle body. Pics of that soon. I left the water passages open on the throttle body.

 

 

I also built half of the downpipe and a pipe to connect the turbo to the airbox.

 

 

Which was also primed / cleared

 

My flange is only 1/4" steel. I might need to replace this if it warps in the future. I didn't have anything thicker on hand. This lenox bi-metal hole saw from the depot, with a little cutting oil, worked nicely on the plate. It makes an awful noise though.

 

Lastly, the valve cover. I primered, painted and cleared this one. Its the same silver as the details on the intake manifold.

[rztmartini]

wow that looks nice! where did you get your bent tubes from or did you bend them yourself?

[mikeatrpi]

I bought mandrel U bends from JC Whitney, then cut and welded to fit. Thanks for the compliments!

[mikeatrpi]

Question for you all - should I replace my head gasket before I swap over to the turbo? If I blow it, is the car still drivable (limp it home) or am I looking at a tow bill?

 

I will need to drill and replace one, maybe two, exhaust studs on the head. I also suspect the valve seals could use replacement. Both of these are easier with the head out of the car... sigh. Its only money, right?

[Pyro]

Question for you all - should I replace my head gasket before I swap over to the turbo? If I blow it, is the car still drivable (limp it home) or am I looking at a tow bill?

 

I will need to drill and replace one, maybe two, exhaust studs on the head. I also suspect the valve seals could use replacement. Both of these are easier with the head out of the car... sigh. Its only money, right?

 

 

I would re-torque the heads bolts. Break each head bolt loose the re-torque to the correct spec (one at a time, using the correct head bolt torque pattern).

[mikeatrpi]

Time for an update.

 

I built a megasquirt kit... thanks, diy-auto tune. MS1 v3.0, with MSnS firmware.

 

I locked the distributor advance by removing the vacuum actuator and welding the advance screw to the lower plate. I tested this in megatune with an electric drill spinning the shaft. Seemed to work ok for a first test.

 

I did a little junkyarding too. I couldn't find a 240sx, so I grabbed this TPS from a quest minivan. It works! I had to build an adapter plate, with holes drilled and tapped to accept the new TPS.

 

The turbo is ready to run... I had to clock my turbo a little bit by loosening the six compressor nuts and rotating the housing. I also cut a section out of the wastegate actuator rod, threaded it with a 1/4-20 die, and installing an external spring. I adjusted the external spring tension so that the wastegate opens at only a few PSI.

 

Finally - I serviced the fuel injectors. I disassembled and soaked them, blew them out with compressed air, and installed new o-rings and filters from cruzinperformance. I also cut and welded off the cold start injector.

[X64v]

If I blow it, is the car still drivable (limp it home) or am I looking at a tow bill?

 

Yes, as long as it only blows out the side of the block (compression leak only, no oil or coolant passages hit), you're good to keep on driving. I blew a head gasket in Phoenix, then drove it back to Tucson (~100mi), then to school for a week while I waited on the gaskets. No big deal, the psh psh psh gets a little annoying though. OEM head gaskets (from MSA or the original Nissan supplier, not Felpro or the like) are cut in a specific way to blow out the side of the block without distorting coolant/oil passages.

[mikeatrpi]

Cool Sean, thanks for the answer. I remember seeing your head gasket photo describing proper orientation in your build thread.

 

I will be PMing you soon, looking for a good MS map to get started with. I am a few weeks away from installing this beast...

[X64v]

Cool, I'll dig up my fuel and spark maps from when my set up was closest to yours.

[Straight6Z]

Finally - I serviced the fuel injectors. I disassembled and soaked them, blew them out with compressed air, and installed new o-rings and filters from cruzinperformance. I also cut and welded off the cold start injector.

What did you soak the injectors in?

[mikeatrpi]

I soaked them in fuel injector cleaner, per this guy's instructions: http://fordfuelinjection.com/?p=82. It smelled like kerosene though. The cleaner did darken a little bit after several hours, but it wasn't nearly the dramatic transformation I was expecting. Either the injectors I bought from Derek were in really great shape, or my cleaning experiments were flawed. I won't really know until I put them on the car and try it.

 

I bought new plugs from a guy on EBay for $2 a piece, and the filters / pintle caps / orings from cruzinperformance (rich jensen). I'm pleased with both of their products... particularly Rich's thoroughness. We talked on the phone and emailed several times to ensure I was purchasing the correct parts. I used an ez-out to pull the filters out of the injectors. I couldn't get a screw to grab.

 

Make sure to test the resistance of the injectors and also use a battery to fire them off and on when you're blowing out the crud.

[Tony D]

Neat injector filter removal idea...I'd not thought of that method!

 

Thanx fer photos!

[mikeatrpi]

Another update. I took a few days off work to start the swap. I'm going to need to burn a few more to get this finished... Let's say I had a few set backs.

 

I was able to ez-out both the front and back studs which were broken off in the head. I chased some of the threads with a tap (I know its not the proper way to do it) and installed studs to hold up the exhaust manifold. I later backed out the studs and used the nissan bolts. My manifold must have been pretty warped, because I had to do a little trimming with my grinder and dremel. This is a fel-pro gasket with copper spray.

 

I had to modify my oil drain slightly too, since my initial measurements when I tapped the NA pan must have been wrong. I cut a pie slice, bent, and welded the drain. Its great and it still clears the steering rack housing.

(no bolts or hose clamps yet - this was a test-fit)

 

I pieced together a downpipe and exhaust system using 2.5" mandrel bends from jc whitney. The oxygen sensor bung is actually an 18mm spark plug non fouler that I cut in half and welded on. I found that tip in the archives. I now have 2.5" exhaust from the turbo to the cat, and 2" out a straight pipe. I'll replace the back half in the future.

 

There's so much left to do... finish the drain, do the oil feed, install the intake manifold and all the other stuff...

 

Question for the MS crew - when installing my distributor, does anyone have tips for lining it up and setting the angle in megatune?

[X64v]

My dizzy (exact same as yours, ZX NA VR dizzy, welded up) is set pretty much in the middle of both adjustments on the plate (middle of plate to dizzy, middle of plate to base). This gives me a 122 degree trigger angle (77 +45). So put it right in the middle, try my numbers, set the timing to 10 degrees btdc fixed, and using a timing light, dial your trigger angle in 'til the timing light shows 10 degrees btdc.

[mikeatrpi]

At the risk of sounding really dumb...

 

Do I need to set #1 to TDC? Do I then need to orient the rotor in the distributor (by loosening the screw and turning the assembly I welded) so it points to #1? Or does none of that matter and the computer handles the adjustments??