Favorite engine swap and why thread - Page 4 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Corbic · 05-31-2013, 03:19 PM

Quote:

Originally Posted by 240boi115

ive heard the ap1 differentials are weak/ tempermental.this true?

This tells me you have no buisness attempting an exotic swap swap.

You are not going to be swapping rear ends.

Corbic · 05-31-2013, 03:20 PM

Quote:

Originally Posted by Flicktitty

I have a GTE Swapped S13. with a Precision 6262 on 19psi through an automatic (stock tq converter) car made 400whp. and got 32mph on the freeway on a 200mile trip.

32mph on the freeway? Did you get a ticket?

If you met mpg, either you ate lying or you have no idea how to calculate mpg.

DS562 · 05-31-2013, 03:45 PM

Quote:

Originally Posted by 240boi115

i ihear ya manworking on my buddies na z32 was hell changing the oil filter and maintinence is hell

so im assuming you own a 300zx? in which case yes... stay na lol any other car boosted is awesome and easier to work on IMO. i would never boost an 86 though. it jus tfeels wrong to boost an 86

yep. i have no power steering or AC and dual electric fans its still a bit crowded in there. not nearly as bad as it was straight from the factory... my oil filter is pretty accessible but i think i would sacrifice the space for 2 more cylinders.

Kingtal0n · 06-09-2013, 05:50 PM

Quote:

Originally Posted by Corbic

Considering a stock NA 2JZ can't even do 25mpg I'm calling bullshit.

People build 550whp LS engines for pocket change*.

Fuel economy has very little to do with the engine you are using. Unless its a horribly mismatched vehicle/engine displacement (1L engine vs 4000lb vehicle or something silly)

In a 2500lb vehicle, any 2.0, 3.0, or even a 6.0L modern EFI engine should be able to put down 28mpg.

Quote:

Originally Posted by Kingtal0n

engine size/manufacturer has little to do with fuel economy. It mostly comes down to vehicle weight, rolling resistance, and rotating mass (assuming we are talking about sequential fuel injection and proper tuning). The 2j has a fair amount of rotating mass AND engine weight, so usually swaps in a 240sx end up around 3200lbs and with an automatic trans net about 25mpg. with a six speed it gets a little bit better. and with some lightweight rotating components such as alumnium rods and lightweight flywheel/driveshaft etc... it gets better and better.

But the same applies to say... an LSx engine. You can also get 25mpg out of that in the 240sx chassis... mainly for the same reason- final vehicle weight is around 3200lbs.

It all adds up, Look at an SR20DET that nets 30mpg such as the s15 six speed swap. The low rotating mass (compared to the automatic transmission) and numerically low gearing (3.4x at the rear differential) help keep the energy lost to turning the internals of the sr20det low. In other words, it takes X horsepower to push a 3000lb car the same distance no matter what (forget wind resistance). Now as you reduce engine RPM, you reduce energy lost due to turning components. So as we lower and lower the cruise RPM of that 3000lb vehicle we use less and less fuel to go the same distance. Thats because you have to first calculate the HP required to move that 3000lb vehicle- and THEN add the HP required to turn every single drivetrain component at a given RPM. That cost decreases as RPM decreases, generally. but the cost to push the car remains the same.

Bmxer300zx · 06-10-2013, 07:49 AM

So you're saying a 1985 302 v8 in a miata is going to get the same mpg as a 2jz 240sx? And I wanna know where you get your vehicle weights from because your lsx 240sx is 100lbs lighter than a fucking 4door 1jz cressida.

Kingtal0n · 06-10-2013, 08:46 AM

Quote:

Originally Posted by Bmxer300zx

So you're saying a 1985 302 v8 in a miata is going to get the same mpg as a 2jz 240sx? And I wanna know where you get your vehicle weights from because your lsx 240sx is 100lbs lighter than a fucking 4door 1jz cressida.

Did you not read: "modern EFI engine" a 1985 is not a modern EFI engine. V8's from pre-95 era tend to be sloppy and have reduced fuel economy and increased emmisions because of it. once you hit 1995+ especially 1998 era things got much better for V8's.

A 1998 LSx engine in a Miata should do 30+ mpg easily.
And weights are subjective. most 240sx start around 3000lbs, usually less. Sometimes as low as 2600lbs. A 2j only adds a hundred or two or three to that, usually 3200lbs or less is the final weight.
But we can gut and tube it to get it lower.

itsjustdaphne · 06-10-2013, 09:17 AM

Quote:

Originally Posted by just a guy

how about a vh45 in a s13????

My brother has VH in his Z32. After swapping in I think 4 of them now, I look at it more of a daily driver v8 swap. Why? Inconsistency at the track. Some say it's the weight of the Zed but there's a Kouki S14 in local events with the same issues. It's easy to swap and most would be happy with the upgrade if they are looking to go V8. For street messing around with a couple of power slides mixed in with the daily drive, it's a great motor.

But anyway,
I personally like the 1jz, and will most likely swap one into my S13 in the future.

The Dude · 06-10-2013, 09:41 AM

Quote:

Originally Posted by Kingtal0n

Did you not read: "modern EFI engine" a 1985 is not a modern EFI engine. V8's from pre-95 era tend to be sloppy and have reduced fuel economy and increased emmisions because of it. once you hit 1995+ especially 1998 era things got much better for V8's.

A 1998 LSx engine in a Miata should do 30+ mpg easily.
And weights are subjective. most 240sx start around 3000lbs, usually less. Sometimes as low as 2600lbs. A 2j only adds a hundred or two or three to that, usually 3200lbs or less is the final weight.
But we can gut and tube it to get it lower.

I have a stock Miata and it doesn't get 30mpg.

Kingtal0n · 06-10-2013, 09:57 AM

Quote:

Originally Posted by The Dude

I have a stock Miata and it doesn't get 30mpg.

It needs an LSx drivetrain with six speed to get the 30mpg. My stock 240sx gets 24mpg but with an sr20det @ 400 horsepower I get 30mpg.

furthermore, I bet your OEM engine would put down 30mpg if (choose some):
you refreshed all the oil seals including piston rings in the engine and increased the compression ratio
you reduced the engine RPM on the highway
you fine tuned the engine to cruise around 15.2:1 air fuel ratio
installed high efficiency / highly atomizing fuel injectors with sequential EFI
increased the strength and size and duration of the spark at the plugs (MSD box comes to mind)
reduced rotating mass of components such as flywheel driveshaft wheels accessories
reduced the drag of wind resistance by lowering the vehicle or altering its shape

Lots of things you can do to improve fuel economy. I can think of many more but Ive got to go to class now.

The Dude · 06-10-2013, 10:25 AM

From experience swapping an LS1/T56 combo into my S14 and also having a KA and RB25 in the same car, the mileage does not go up; it goes down.

Big Zee · 06-10-2013, 10:56 AM

personally my motor swap of choice, would be a SR20 or 22VET. for a S-Chasis

reasons are
lightweight motor
higher revving still
unique motor still
no broken rocker arm worries
make lots of power for days
clean looking swap that looks like it belongs there.

saving up for it, but for now rocking a redtop SR

Bmxer300zx · 06-10-2013, 12:06 PM

Quote:

Originally Posted by Kingtal0n

Did you not read: "modern EFI engine" a 1985 is not a modern EFI engine. V8's from pre-95 era tend to be sloppy and have reduced fuel economy and increased emmisions because of it. once you hit 1995+ especially 1998 era things got much better for V8's.

A 1998 LSx engine in a Miata should do 30+ mpg easily.
And weights are subjective. most 240sx start around 3000lbs, usually less. Sometimes as low as 2600lbs. A 2j only adds a hundred or two or three to that, usually 3200lbs or less is the final weight.
But we can gut and tube it to get it lower.

.
No I did read but you also said engine size doesnt have much to do with fuel economy its simple more cyclinders/bigger displacement will use more fuel even at idle with no mass being moved through drivetrain. Now comparing a 6.0 vortec to a old 2jz is dumb you're talking 2 different engines from different times. N2m most people who go to a v8/lsx swap have a tendancy to strip it of ANY economy related componants even such the ecu is retuned so how can it give more mpg after all that than the vehicle rated mpg it came from?
Now if you slap it in miata vs a vette I can understand a bit of a mpg gain but not to where people should be thinking " well if I ls1 my miata I'll get better mpg's than a 2jz in my 240sx cause it's lighter..

Bmxer300zx · 06-10-2013, 12:09 PM

Quote:

Originally Posted by The Dude

From experience swapping an LS1/T56 combo into my S14 and also having a KA and RB25 in the same car, the mileage does not go up; it goes down.

Thank you my mx83 with a sr20det had alot more mpg than the pos 7mge and my rebuilt Na z32 did. That's a smaller displacement motor in a car weighing at 3400 lbs before weight reduction.
.
This guy up here claiming a smaller displacement engine in a heavier chassis gets less mpg is making no sense

Kingtal0n · 06-10-2013, 01:55 PM

Quote:

Originally Posted by The Dude

From experience swapping an LS1/T56 combo into my S14 and also having a KA and RB25 in the same car, the mileage does not go up; it goes down.

what was the vehicle weight before and after the swap?

because that's what really matters.

And of course, you will need to have data logs of the fuel injector duty cycle, fuel pressure, and compare with road speed in real time to know for sure.

Because an engine like an LS-X will use more fuel if you are not setting cruise control and driving at a steady speed for 100% of your calculations. Accelerating, for instance, can eat up a significant amount of fuel since the engine is capable of producing so much more horsepower.

Kingtal0n · 06-10-2013, 02:03 PM

Quote:

Originally Posted by Bmxer300zx

.
No I did read but you also said engine size doesnt have much to do with fuel economy its simple more cyclinders/bigger displacement will use more fuel even at idle with no mass being moved through drivetrain. Now comparing a 6.0 vortec to a old 2jz is dumb you're talking 2 different engines from different times. N2m most people who go to a v8/lsx swap have a tendancy to strip it of ANY economy related componants even such the ecu is retuned so how can it give more mpg after all that than the vehicle rated mpg it came from?
Now if you slap it in miata vs a vette I can understand a bit of a mpg gain but not to where people should be thinking " well if I ls1 my miata I'll get better mpg's than a 2jz in my 240sx cause it's lighter..

You are still thinking from the perspective of engines. Physics doesnt care what engine you are using; it takes X amount of horsepower to push a vehicle with a weight of Y. Simple as that, end of story. Keep swapping engines all day and the mileage will be similar as long as the overall efficiency of the engines is similar. A 2j has a very similar efficiency to an Lsx; actually the Lsx should be a little bit better.

Using your example as an engine is idling. Comparing an SR20 with an LSx engine. I agree that the LSx has heavier rotating components, and should use more fuel at idle. But if you actually calculate the horsepower requirement between the two engines rotating, you will find the difference is negligible. that is, the lsx may require more horsepower to turn, but it will also probably idle at a lower RPM which will reduce the horsepower requirement. But that is also negible. What really counts is the fact that both engines require a very minimal amount of horsepower to turn, the difference is probably less than 1horsepower overall between the two. Which means differences in idling fuel requirements will also be negible.

But that is all overlooking the fact that the LSx has a higher compression ratio and therefore extracts MORE horsepower per ounce of fuel burned- therefore, the lSx most likely uses less fuel overall than the SR20 does at idle.

Bmxer300zx · 06-10-2013, 03:09 PM

Quote:

Originally Posted by Kingtal0n

therefore, the lSx most likely uses less fuel overall than the SR20 does at idle.

Wow... just fucking wow

06-10-2013, 10:56 AM	#101
Big Zee Zilvia Addict Join Date: Oct 2005 Location: BC Age: 37 Posts: 860 Trader Rating: (10) Feedback Score: 10 reviews	personally my motor swap of choice, would be a SR20 or 22VET. for a S-Chasis reasons are lightweight motor higher revving still unique motor still no broken rocker arm worries make lots of power for days clean looking swap that looks like it belongs there. saving up for it, but for now rocking a redtop SR __________________ Two-Tone owner#011509-Lightly Modded

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

06-10-2013, 07:49 AM	#95
Bmxer300zx Zilvia Member Join Date: May 2012 Location: N.Y Age: 35 Posts: 239 Trader Rating: (0) Feedback Score: 0 reviews	So you're saying a 1985 302 v8 in a miata is going to get the same mpg as a 2jz 240sx? And I wanna know where you get your vehicle weights from because your lsx 240sx is 100lbs lighter than a fucking 4door 1jz cressida.

06-10-2013, 10:25 AM	#100
The Dude Zilvia Junkie Join Date: Sep 2003 Location: TN Age: 36 Posts: 357 Trader Rating: (4) Feedback Score: 4 reviews	From experience swapping an LS1/T56 combo into my S14 and also having a KA and RB25 in the same car, the mileage does not go up; it goes down.