Any information on swapping sr20 in z32

[Cody123]

I'm considering swapping my 93 n/a 300zx with a blacktop sr20det just want info on the swap please help anything is appreciated

[DCaff300ZX]

I can't imagine why anyone would do this, and have never heard of it so your search may be a long one...

[raremotive]

It all depends on what you want to do. Keeping the VG transmission or using the SR transmission? Each has it's own set of fabrication. The swap itself isn't rocket science.

The lighter motor of the SR should be a nice touch to the 300zx considering that the VG is heavy.

You will have to consider your suspension to help welcome your lighter front end.. don't want to end like this dude..

https://www.youtube.com/watch?v=44DEsy19EH0

[evildky]

It's been done, I wouldn't recommend it, yes it a lighter motor but it's still a heavy car and while the SR can make big power it has to work 50% harder to move the same amount of air to make the same power. it's just taking a more difficult path to the same location.

[raremotive]

^ Black-Top SR20 makes 202 HP from factory w/ 7 lbs of boost. That's equivalent to a 2.95 litre (14.7+7 psi boost/ 14.7 * 2 litres). Just dialing an additional 0.5 psi, the motor is now equivalent to 3.02 litres. Motor isn't working any harder to move air. Turbo is though..with wasted gases anyways. It's a better, not the best, alternative than the na VG30.

VG30TT will blow SR out of the water with this comparison without a doubt. About 275 lbs heavier, the VGTT is able to produce enough power to overcome that easily, at the cost of some handling and braking.

Quite frankly. I would prefer a four over a v-6. And a single over twin turbo for simplicity of maintenance.

Granted SR is from a 2700 lb car.. in a 300zx.. scale would be closer to 3263 lbs. A 500 lb weight shaving isn't too difficult to achieve either. Just the seats alone will take care of half of that.

This guy took his car down to 2,300 lbs using an SR20
https://www.youtube.com/watch?v=4t7qorwfEfw

[rgregoryb]

I would love to put a Ford EcoBoost V6 in my Z. someday.

[raremotive]

I would love to put a Ford EcoBoost V6 in my Z. someday.

Wha... if it's a Ford.. you should be drooling over the 5.2 voodoo.. it's 526 hp all naturally aspirated..

[rgregoryb]

And quite pricey, I'll just buy a Ford GT and swap engines

[rgregoryb]

Can't buy the voodoo yet, have to settle for the Aluminator XS at 500+ HP for $14,400

[DCaff300ZX]

Wow...I stand corrected.
Well, go ahead and put a 4 banger in that heavy old Z32...be my guest!

[evildky]

^ Black-Top SR20 makes 202 HP from factory w/ 7 lbs of boost. That's equivalent to a 2.95 litre (14.7+7 psi boost/ 14.7 * 2 litres). Just dialing an additional 0.5 psi, the motor is now equivalent to 3.02 litres. Motor isn't working any harder to move air. Turbo is though..with wasted gases anyways. It's a better, not the best, alternative than the na VG30.

You are in the ballpark, assuming 100% volumetric efficiency (VE) on each motor, which of course they are not. The n/a SR moves 2 liters per revolution (actually it takes 2 revolutions as these are 4 stroke engines but you get the point), the n/a VG would move 3, all things being equal. Adding 14.7 psi of boost to either would double the amount of air moved through them meaning double the amount of power produced. 3 liters of air with a stoichiometric fuel mix will yield 50% more power than a comparable 2 liter assuming equal VE.

Ultimately both would be limited by their turbo (s), you want to make 500 hp, you'll need a turbo or turbo's capable of moving nearly 60 lbs/min. The turbo(s) don't care what motor they are bolted to, they must spin at a certain speed to move the same measured amount of air. a given volume fo air can only yield a certain amount of power. Granted a larger engine will spool a smaller turbo faster and of course tuning can ramp up spool rates.

So if the VG made XXX whp at 4000 rpm the SR would need to spin at 6000 to move the same amount of air and make the same power. also each piston and rod in the VG would bare the force of XXX/6 whereas each rod and piston on the SR would bare the force of XXX/4 which means 50% more stress on these internal parts.

So yes the swap can be done, it's just not the cheapest or easiest way to make power in the Z32.

[raremotive]

^ I would disagree. SR basically drops CR to 8.5 which gets you terrible volume efficiency by itself. It gets better VE when the turbo is added on. It's a designed system. SR had to give up some efficiencies.. lower CR, higher back pressures..etc... in order to reap the benefits of a turbo. Nor is the turbo independent of the engine either.. The turbo depends on the heat the pressure the engine produces in order to help produce the higher air density for the engine.

Doing a NA comparison of SR is basically taking it out of what it was designed to do. The thing about boosted applications, yes.. the NA SR20 at 5000 rpm moves less air than the NA VG. But as soon as you crank the turbo pressure up to match the VG's power at that rpm.. the air density the same. Granted that it requires proper turbo sizing and cooling ... and you have to deal with turbo spooling / lag... it's a designed system.

Additionally if we are comparing SR20 vs NA VG... since the turbo is converting wasted heat to positive pressure/increased density, the engine does not have to work as much to get the air in the engine. In essence it reduces the pumping losses a NA engine would have to bear. This reduces the counter torque your pumping pistons create while the power is transmits. This in turn reduces torsion stresses within the crank... in other words net power is higher due to having more positive torque than negative thus reducing your torsional fatigue amplitudes that the crank sees.

You are right that that the you do have to deal with 50% more power per component. However, the stresses is not 50% more. There are other variables such as shorter crankshaft length, smaller distance between mains, less total mass of rotating and reciprocating components that come to play and reduced pumping losses that I mentioned above... I am too lazy to spend the time to ball park it, but with certainty it's a bit lower than 50% in stresses. The beauty of this is that it can handle this power, other things fail before a short block does.. no different than any other engine.

If you want 500 hp... I would agree that SR would not be the cheapest. But I would still say it's cheaper than a na VG to make that power. You would be flirting with danger to make reliable 500 out of even a VGTT.

However, 4 is less than 6 when you have guts to replace. And you have a roomier engine bay when you do have to service it.

[evildky]

No, you're not quite getting it.
The SR and VG both came available in both N/A and Turbo configurations from the factory, which is why it's not fair to compare the SR20DET to the VG30DE. Both engines offer higher compression ratios in their n/a versions. Lowing the compression ratio through piston design which is what nissan did has little to no effect on the VE. Increasing the compression ratio has little effect on power output of a turbo motor. You want more power, you need to move more air, and starting with a bigger air pump is how we do that.

Air density is it's own discussion, assuming both engines are adequately intercooled the air density would be the same for both, don't confuse psi for lbs/min. Lbs/min is a measure of volume over time, psi is a measure of resistance, the higher the VE of a given engine the lower the psi will be at the same lbs/min.

Your third paragraph makes pretty much no sense. A turbo is a restriction in the exhaust so yes it does take power from the engine to power the turbo, the turbo more than makes up for this by generating boost on the intake side.

Your fourth paragraph is almost correct, Yes the VG has more moving mass but it's also moving more air so if we actually break down the rotating mass per volume of air moved it's going to be nearly identical. The VG crank shaft holds 50% more rods but is actually nearly the same length. Yes the SR has more mains but the block isn't the weak point of either motor, it's the pistons.

Whatever the HP goals it's cheaper to do it wiht the VG. the cheapest way to make power wiht a VG is to start with a turbo model. There is power to be had form the n/a VG but it cost twice as much to get half the power.

[raremotive]

I am looking from a perspective that we have a 300zx with a NA VG. On paper it's not fair to compare the NA VG against an SR20. But as a replacement is how I am basing my comparison. As I said in my first reply to you the VG30TT will blow this comparison out of the water. Any boosted motor will be better replacement in terms of power.. since one could just simply turn up the boost.. as long as they stay within the allowances of the block.

I stand corrected. Lowering compression lowers thermal efficiency, not volume efficiency, however the increase in back pressure lowers volume efficiency... turbos replace the volume efficiency from the increased back pressure and on average reduce the pumping losses from part throttle applications. Hence the third paragraph that that doesn't make sense, I probably condensed it more than I should of.

Pressure Volume diagram of a engine:


Net Power = Power Loop - Pumping losses

Pumping of air creates a negative torque on the crank. Reduced pumping loss means reduced negative torque. Cylinders alternate suction, compression, power, exhaust... which changes whether the rod is in tension or compression.. which can either contribute to torque production or hinder it. Consider the entire crank with all the forces applied for each cylinder. This alternating force is what creates fatigue stress. If you reduce the negative torque, you reduce fatigue stress.

Touche about pistons, both are within 1 mm in diameter. SR20 piston should see 50% more stresses. Actually since the SR piston is 1 mm smaller than the VG, it will probably closer to 52%. I was busy looking at the skirt and not at the blouse. However, I still stand by that the short block is the least of worries... provided that you are applying the correct power for the application. Both VGTT and SR are going to need forged if you want a reliable 500 hp.

Pressure is related to density by the ideal gas law.. PV=nRT. It's how mass flow rate is calculated and why MAP sensors can be used to determine mass flow rate. So pressure, volume, mass and density are common terms used to quantify how much air gets into an engine. Hence why I used pressure ratio in my first reply to you. In the end it's about how much air mass ends up in the cylinder.

I would disagree about needing to move more air by having a bigger air pump to create more power. If that was solely true Nitrious oxide systems would not be considered. Even I could simply pour liquid nitrogen over the plenum, and that itself would increase the power the engine without changing the size of the pump. Both operate on the same principle of increasing air density by cooling.

That's essentially what the turbo is doing. Increasing the density of the air from mechanical work generated by the wasted heat of the engine. Granted it's a air pump itself.. a lousy one if that 20% to 30% of it's work is converted to heat.. hence needing an intercooler to make it even effective option... a making it all a designed system of two pumps.

Even by having a smaller heat sink of a block and lots of air room in the engine bay lowers the inlet temperatures which it is a slight power bump.

I would still argue, even the initial cost maybe slightly higher. But overall cost of upgrades and maintenance will prove to be much lower. Making the overall cost lower.

[DCaff300ZX]

Now THAT was a fun read!!!!
But since both jobs (NA VG prepped for 500+ HP, and 500+ HP SR20 swap) would be SO costly and difficult to do especially compared to just having a TT prepped for 500+HP, I still can't see any reason to go to all of the trouble of a SR20 swap, same as the high costs and lower returns for modding a NA VG. No use comparing fruit when you need BEEF.

[evildky]

So we agree the SR20DET to VG30DE is not a fair comparison.

We basically agree, adding a turbo increases the VE of the engine to well north of 100% depending on boost levels.

Yes I can agree that this puts more stress on the crankshaft, the crank on the VG is good to 600-700 hp (some even more) so arguing stress on the crankshaft is pointless.

Yup pistons are weak.

Agreed, most people don't understand that 7 psi from a 30 lb/min turbo is half as much ait as 7 psi from a 60 lb/min turbo.

We still aren't on the same page here, there is a reason cruise ships aren't powered by 2 liter 4 cylinder engines. yes, nitrous is chemically adding oxygen and cooling the charge increasing the density even further. By super cooling the intake you don't increase density you preserve it.

Yes the turbo is also an air pump, powered by the primary air pump, but a boosted 6 liter engine has the potential to make more power than a boosted 1 liter. The same way that a 60 lb/min turbo stands to make more power than a 30 lb/min turbo. Low boost can be effective without an intercooler, all the factory turbo S12's, S130's and Z31's lacked intercoolers but none ran more than 7 psi. I did manage through tuning about 10 psi without an intercooler, adding the intercooler dropped intake temps by 100 degrees.

Not so sure it would be a measurable difference, but theoretically yes.

Back to the main point, running wrecked TT donors (although hard to find) can be had for less than the cost of all the bits needed to convert to SR, if buying just the engine the SR. The cost of buying an SR looks to be a bit more than buying a VG30DETT, difference being the VG bolts right in and plugs right in, there will be additional work to convert to the SR meaning extra cost. can it be done yes, it's still the long way around.

[raremotive]

^ Agree on paper comparison. As if we are starting with a clean state. However we are not. VG30-NA is the motor to be replaced. So that's how I am basing my comparison from.

Cruise engines are a whole another beast... they are actually replacing larger engines in favor for smaller and larger quantity engines. It's as equivalent of replacing a 6 litre v-8 to for four 0.5 litre inline-turbo engines. These beasts usually run at a constant rpm for maximum efficiency. Having smaller and lighter engines improves efficiencies from 60% to 75%, reduces weight, improves fuel economy and emissions. Also, the common failure.. crankshafts. Hence having 10 small engines on a container ship, it's easy to replace 1, than a single larger engine.

If we take either stock engine and crank up the power. The piston is most likely to fail. Agreed. However if one plans on having 500 hp. He replaces with forged. Short block is now the least of his worries. Yes. A inline 4 has less of a threshold than a v-6. However the threshold of an SR20.. will still produce more power than the stock VG30 na that's in there now.

In a engine, the volume rate is constant.. it's set by the size of the piping, plenum, and cylinder. These cannot be changed. However, the variable that is critical to power production is temperature because it influences the density of the air... density as in.. mass per cubic volume. The higher you can get these density, more air mass you pack in that constant cylinder volume. So by injecting water on or inside the engine increases power by reducing temperatures. Same effect with nos.. and so on..

Another is pressure.. you make more power at sea level with 14.7, than you do traveling i-80 at the highest point 8,640 feet, in wyoming with ~10.5 psi .. effectively making a 3L into a 2.14L engine. Pressure is force per cubic volume. This force is acting on the air. On Earth pressure is created by the stacking effect of air thanks to gravity, hence why the lower you go in altitude the more pressure you have. Drag strips are usually placed at below sea levels just to get that extra-oof.

Inside an engine with constant volume the also has the same stacking effect, air has no other option but to compress by increasing in density. This is why turbos increases density, but also at a cost of temperature increase from increased pressure and efficiency losses. The increase in temperature is the reason why non-intercoolor turbo systems were limited to 7 psi. Adding the intercooler would of improved power by at most 20%.. and you could still crank up the boost for more.

As I said before. The initial costs is a little bit higher with SR. However upgrading per cylinder will be around 40-50% cheaper. That also include maintenance, 40-50% cheaper. If we look at the life of the engine in the car, not just putting it in. It would yield a cheaper overall cost. You get yourself a lighter engine that improves handling and braking. You also get a roomer engine bay that allows ease of maintenance as things begin to break or when you want to bolt on your next upgrade.

[z32loverboy]

Man this chemistry homework hurts my head. lol

[DCaff300ZX]

^^^^ I hear that, but I won't be missing any of it!
LOVE it when two people who know what they are talking about and can back it up disagree, LOTS to learn there...

[evildky]

lol, I think we scared the OP away

[raremotive]

lol, good times.

[DCaff300ZX]

lol, I think we scared the OP away

People gotta know we don't fool around here, yo!

[NolimitZ32]

I am so glad I came back, this is awesome, it made my nerd hard erhm um yeah that

[Cody123]

The reason why I want to put the sr is because I'm sick of the unreliable vg30 plus I'm going to drift my 300zx well going to try and drift it, it has been done in Japan and one dude in Cali but the real reason is in sick of the lack of space and plus too twin turbo a vg in better off selling my n/a and buying a tt but all the info about the swap was very helpful thank you

[evildky]

VG30 isn't unreliable. Anything 25 years old that hasn't been properly maintained can be a problem. The Z32 is the most difficult to service and uses the most proprietary parts of any generation of z car and had the lowest production numbers making parts rare, expensive and difficult to service. Any "Low miles JDM engine" that comes on a pallet is miles unknown, condition unknown and is likely to be as problematic if not more so than the lamp you have. If it comes on a pallet it's a core, plan on rebuilding it and replacing all the broken bits. For the cost the Gm LS swap would be the better choice, seems nearly every drift car on this continent has an LS swap. Instant torque, massive parts availability, lightweight, compact design.

[NolimitZ32]

^ 100% agree, the SR will give you what you want but that feeling wont last long and even after peaking the SR you will still head for the LS platform.

[raremotive]

VG30 isn't unreliable. Anything 25 years old that hasn't been properly maintained can be a problem. The Z32 is the most difficult to service and uses the most proprietary parts of any generation of z car and had the lowest production numbers making parts rare, expensive and difficult to service. Any "Low miles JDM engine" that comes on a pallet is miles unknown, condition unknown and is likely to be as problematic if not more so than the lamp you have. If it comes on a pallet it's a core, plan on rebuilding it and replacing all the broken bits. For the cost the Gm LS swap would be the better choice, seems nearly every drift car on this continent has an LS swap. Instant torque, massive parts availability, lightweight, compact design.

I can vouch for this. The LS package is in the ball park being 50 lbs heavier. However the parts availability is amazing. There's something to be said being able to go to any local parts store to buy replacement parts on track day.

Another benefit is torque is flat from nearly idle to redline. This means it's easier to modulate when doing your drifts. Unlike any turbo engine where you need to put extra effort to keep your rpms up to keep the turbo spooling.

Again, swaps are not hard.. even easier if you can fab stuff.

[Cody123]

The whole look I want for the z is to base it off Japanese street style drifting because anyone who wants power instantly will swap a v8 engine to gain but where is the style in that i want the car to look and perform as a Japanese car should in Japan they do not swap v8 into there drift cars lol but I will agree 100% that the v8 will perform the best just really lacks style in a Japanese car

[Cody123]

Is there any advice on trying to preserve the vg in it now it's gonna go under abuse drifting while I build the sr

[Hackysac300zx]

vist https://www.facebook.com/groups/1625653547714759/

If you want to do this that will give you all the information you need...ive also heard the weight/power argument...what about the 2.0t Genesis? it actually weighs more than the Z32 and puts down impressive numbers...Idk much about the tech. aspect but I would assume if Hyundai can do it...