can anyone tell me what id be getting into if i decided to convert my NA 88 300zx to a turbo? not looking for a nightmare project. Just curious as to what parts i would need.

T3 Turbocharger and exhaust elbow from 84-87 300ZX Turbo
Drivers side exhaust manifold
Downpipe
Front crossmember (both the crossmember and engine mount bracket must be swapped for turbocharger fitment)
Drivers side engine mount bracket (bolts to block)
All intake piping (from Airflow meter to Throttle body)
Alternator mount, tensioner (and longer belt for application because the alternator mounts on pass. side instead of drivers side)
Oil pan
Turbo oil lines (and water lines if applicable)
Fuel injectors (260cc/min instead of 180cc/min)
Correct ECU
All applicable gaskets


I got this from here:

(1984 model, but shouldn't be much different)
http://www.redz31.net/pages/turbo.html

I would also want to know what compression ratio pistons I had in the NA engine. The L-28 turbo engines used dish-topped pistons for their turbo applications to avoid excessive compression pressures (aka blowing the head off the engine under boost). The L-28 Naturally Aspirated engines could afford to have flat top pistons with higher compression.

High compression pistons don't play well together with turbochargers.

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1970 240Z

N/A z31's are 8.5:1 and respond awesomely to a turbo conversion. So much more repsonsive it is like a different motor, makes you wonder why Nissan just didn't make them all 8.5:1 instead of the lame 7.8:1 in the turbo blocks.

BTW, only difference is the pistons everything else is the identical. Yes, even the cams.

So, the NA pistons are 8.5:1 and the turbo pistons are 7.8:1.

The early 240Zs were 9.8:1 with the E-31 head. Mine was milled to 10:1. But I also own an L-28 dish-piston turbo block which I can play with this year.

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1970 240Z

Now that we are on the topic, does anybody want to explain compression stuff to me, or should I stop being such a newbie and google it for myself?

it is a little it more involved than a simple post can explain. An hour or so googling will yield vastly better info than I can articulate through my caveman brain.

True, but I'll try ~

An engine's Compression Ratio (CR) tells us how much volume (in each cylinder) is squeezed (or compressed) into the combustion chamber of each cylinder. It is normally expressed in terms such as "X:Y", where X would be the cylinder volume and Y would be the combustion chamber volume.

Using the bore and stroke of one cylinder, you can compute the volume of it. When the piston is at the top of its stroke (Top Dead Center, or TDC), the tiny area remaining above it is the combustion chamber, where the spark occurs which burns the air/fuel mixture and pushes the piston back down. That "pushing" of all the pistons, one at a time, is what propels the car, or lawnmower, or motorcycle, etc.

So the difference btwn cylinder volume to combustion chamber volume is called the Compression Ratio. Up to a point, the higher the CR ~ that is, the more air/fuel mixture you can squeeze into the smallest area ~ the more power the engine produces. But there are limits. If the CR is too high it can damage the engine (actually blow the cylinder heads off) or simply blow head gaskets. Also, the higher the CR, the higher-octane fuel is required to prevent unwanted "pinging" and "detonation".

Lawnmower engines usually have very low CRs; down around 4:1 or so. That means the piston squeezes the volume of the cylinder into an area 1/4 its original size. Race cars typically have CR of 10:1 or more.

Supercharged or "turbocharged" engines must have relatively mild CRs, because they compress more fuel/air content into the cylinder volume than NA engines do. So the NA and 'charged engines might have the same cylinder volume, but the 'charged engine has increased the actual amount of air/fuel it gets into that cylinder volume ~ so it's ALREADY pressurized before the piston squashes it up into the combustion chamber.

If you try to put too much water into a water balloon, it breaks. Same with a supercharged engine with too high a compression ratio. You're trying to squeeze too much into too little. Sir Isaac Newton always wins.

The Turbo engines get better power from a lower CR because it pushes more air/fuel into each cylinder than the NA engine can inhale. Picture it like an athlete on oxygen running beside one who isn't.

Compression ratios are spoken as: "Ten to One". They are not to be confused with Pounds Per Square Inch (PSI) of pressure, which we measure thru the spark plug hole during compression checks. I used to have a chart which showed me the general relationship btwn PSI and CR, but that's long lost. Wish I could find another one.

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1970 240Z

And by the way, once you compute the volume of one cylinder, you can multiply that by the number of cylinders the engine has, to learn the DISPLACEMENT of the engine. That's the total volume of air the engine will inhale & exhale during 1 revolution of the crankshaft. We Yanks describe that in terms of Cubic Inches, as in, "a 427 cubic inch engine". The rest of the world describes it in terms of Liters, or cubic centimeters (One Liter = 1,000 cubic centimeters = 60.66 cubic inches).

So when I say my 240Z has a 2.4 Liter engine, that means the engine displaces 2,400 cubic centimeters (or 146 cubic inches) of air each time the crankshaft revolves.

The 3.0Liter engine = 3,000 cc = 182 cubic inches.

Just in case you were wondering.

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1970 240Z

ANNNND, ACTUALLY ~ you have to be careful about "marketing licenses", which somehow allows car manufacturers to stretch the truth about the sizes of their.....engines.

The 240Z engine is NOT a true 2.4L (2400 cc) ~ it's actually a 2393cc engine, rounded off to 2.4 Liters.

So if you ever get technical with this stuff, trust your math, not the advertiZing.

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1970 240Z

Oh, and one more (FINAL) thing, then I'll step down off my soapbox with apologies ~

There's a large difference btwn a SUPERCHARGER and a BLOWER. It is determined by function and location in relation to the induction system.

A blower sits on top of the carburetor (or fuel injector air body) and pushes raw air into it faster than it could 'breathe' by itself. No fuel ever enters the inside of a true blower. A good example of a real blower would be the old Paxton "superchargers" (misnomer) of the 1950s and '60s Studebakers. A blower adds a reasonable bit of horsepower (10%) to engine output.

A true SUPERCHARGER (or COMPRESSOR) is another animal altogether. It actually receives air/fuel mixture from the carburetor (or fuel injector), COMPRESSES it inside itself, then forces it into the engine below. A supercharger might increase the horsepower output of an engine by 40-50%.

So ~
a supercharger sits between the induction system and the engine and actually handles fuel;
the blower sits on top of the induction system and handles only air.

Today's "Turbochargers" are really, technically, blowers. They are not superchargers. Marketing thinks it sounds better to call them "chargers" than "blowers". Instead of being belt-driven (which would rob some small horsepower from the engine), they use the free force of exhaust which is already being made. The exhaust turns the propeller, which then turns an impeller, which forces air (ONLY) into the carb or injector system.

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1970 240Z

So much information! Thanks!

I've read through it all once, but will have to read it all again a second time(at least) to formulate an educated response. I've got a few deadlines today, but will answer around 4/5. Thanks again!


Sorry for doing this to your thread nemesis. if anyone wants to make this a new thread, go for it.

Ok, I read it again. great information!

So the Garret T3 on the 280zxt is really just a blower-because there's no fuel mixed in, correct?

Also, between a regular 280zx engine and a turbo one, what's the main difference that lies within the engine. Different pistons with a different bore??

i think the conversion sounds like a bit much for me tackle right now. like i said before not looking for a nightmare project.

Right ~ the T3 (or any" turbocharger") is actually only a blower. It never handles any fuel inside it.

The L28 turbo engines had dished-topped pistons to lower compression ratio slightly, because the turbo more than made up for the power a higher compression ratio would have made. By lowering the compression, Nissan gave the engine a safety element. Unless you turned the boost WAAYYY up, you had little chance of damaging the engine.

The bore was the same in both the NA and turbo engines ~ they were all 2.8 liter engines. Only the pistons were different, as far as I know.

The L28 turbo blocks also had a small metal tab at the juncture of the block and oil pan, on the driver's side. That was to prevent the great heat from the turbo from frying the oil pan gasket at the point closest to the turbo (thanks, Mark C, for pointing that out to me years ago!).

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1970 240Z