Best engine for a hypermiler Z

[seanof30306]

What models/years were available in the us with the RWD SR20DE?

[BillZ260]

You've never driven on a race track at 10/10ths for 45 minutes. Get your competition license and do a Spec Racer Ford rental at the next local SCCA event or rent a shifter kart and run a 30 minute heat race.

 

WERD!

 

To both comments actually, but performance driving takes A LOT more out of you simply because if you loose track of what you're doing you can get in to some serious trouble, loose track while trying to get good milage and you... well you get a little worse milage...

 

Welcome to the board Sean, always good to see another Z fan from OK here. If you'd like, I can try to convert you to the power side of Z's but I do applaud your goals, should be a fun project!

[seanof30306]

WERD!

 

To both comments actually, but performance driving takes A LOT more out of you simply because if you loose track of what you're doing you can get in to some serious trouble, loose track while trying to get good milage and you... well you get a little worse milage...

 

Welcome to the board Sean, always good to see another Z fan from OK here. If you'd like, I can try to convert you to the power side of Z's but I do applaud your goals, should be a fun project!

 

My friend, I have been thinking about an LSX Z for some time, and still have not given up on that.

 

But, with gas going the way it is, a hypermiler is on the project list for now. If I'm gonna have a car that gets 40 mpg, why not see if it makes sense to do it with a Z-Car? It'd be a lot more fun to drive than a CRX!

 

I've been drag racing, autocrossing, circle tracking and road racing since I was in my teens. Hypermiling doesn't give you the thrills that those do, but, it does re-engage you in the process of driving. You have to pay attention to hypermile! I find myself driving with the radio off most of the time now, paying much closer attention to the road ahead, the drivers around me, etc.

 

This isn't an either/or proposition. There's no reason why you can't still race, the place where you're hypermiling is in your daily driving, you (hopefully) don't race then, anyway. Hypermiling is just another form of performance driving; just one that saves you money.

 

I'd also bet a hypermiler would still do OK on an autocross course. An aluminum 4 cylinder engine not only weighs quite a bit less than the iron 6 that came in the Z, but it's about 1/3 shorter as well, moving the CG even further back. With that setup, no bumpers, fiberglass fenders and a carbon fiber hood, you could easily be looking at a 2000-2100lb Z car with 50/50 weight distribution!

 

And thanks for the welcome. I'd love to get a look at/ride in your z sometime. I'm in Brookside, what part of town are you in?

[seanof30306]

Saw this on ebay:

 

http://cgi.ebay.com/ebaymotors/Parts-Accessories_Car-Truck-Parts-Accessories__95-98-Nissan-240sx-JDM-SR20DE-SWAP-Complete-swap_W0QQitemZ170218703126QQddnZPartsQ20Q26Q20AccessoriesQQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQddiZ2811QQadiZ2865QQcmdZViewItem?hash=item170218703126&

 

What is it about the JDM SR20DE that makes it preferable to a domestic US model?

 

Also, I looked on fueleconomy.gov. This SR20DE is for a 95-98 240sx. that shows 19/26 mpg and say it requires premium fuel. I don't think that'd be a good candidate for a hypermiler.

[Gollum]

Well I personally don't believe the SR20DE "needs" premium fuel. The compression isn't THAT high. And the 240SX is quite a bit heavier than the car you're looking at putting it in. And the SR20DE you're looking at in the S14/15 have 163hp... quite a lot compared to most of the high MPG engines you're looking at.

 

There's not many RWD applications for the SR20DE here in the USA, so buying a JDM motor might be the best bet, especially if you want the tranny to come with it.

 

You'll be much better off going with the older SR20DE out of the S13, which has 137hp. It's rated to run on regular octane too. It's rated at 10.2 L/100Km for city driving which equates to 23 mpg, so it's reasonable to expect it to run about 30 on the highway. The S13 is STILL a heavier car but a good margin. I can see this engine reaching 40mpg with the right gearing and the right driving techniques, especially if you're going aftermarket EFI and can tune to your hearts desire. And at 137HP it should still be as fast as a stock 240Z, and you'll have less weight to lug around.

 

From what I've seen on people's weights in Z cars you'll be a bit more rear biased than 50/50 distrobution, but that's not really a bad thing.

[seanof30306]

I don't know. Maybe a 2 litre is just too big for this application. Maybe a better solution is to go back to one of the older, smaller engines from the 70's-early 80s before they went on the horsepower craze.

 

A cumbustion chamber designed for maximum power is not necessarily going to be the most efficient for MPG. For example, in it's 5.0 V8, GN utilized swirl port heads, which were great for MPG, but sucked for power. One of the first things you'd do on an L03 (the TBI 5.0) was swap on a set of TPI 5.0 heads. The combustion chambers were the same size, but they weren't of a swirl port design. That swap alone was worth at least 20hp, but you took a MPG hit doing it. I just don't know enough about non-American, non-V8 engines to know which 4cyls would be the best candidates for this swap.

 

Also, would this thread be better placed in the 4cylinder forum?

[OlderThanMe]

Geo metro 3 cylinder attached to an L6 tranny with one RB26 turbo..

[Clifton]

When you're cruising down the highway at 1700 rpm with your fuel tables leaned out to 20:1, something as simple as a severe wind gust or a slight hill can immediately put you into catastrophic detonation.

 

Then there's the gas. Stoich for gasoline is 15.7:1.

 

Cruidin at 20:1 would probably get worse milage than 15:1 unless it was a lean burn engine ( Honda) designed to run at that.

 

As for cruising at 20:1 and then hitting a slight hill and having catastrophic detonation, that's just not true. You don't get deto during light load. Regardless, the hill would add some load. You would come out of the cruise bins and fuel would be added, if anyone one with half a brain tuned it right. No difference than cruising at 15:1 ( or whatever) and 42* timing at 60mph and then hammering it with 30 psi.

[Gollum]

NOTE: Sorry, didn't quote him but this is all in responce to sean's last post.

 

This discussion might be better off in the 4 cylinder section, but you're already 4 pages strong and I think this section is still fine as there might be some other good motor candidates that have yet to be brought up.

 

I see what you're saying, I just figured you wouldn't want a motor that was completely dog slow. The SR20DE would still offer some good punch when you needed/wanted it.

 

The CA series might be your best bet if you want to go down in power technology and displacement. The CA came in 1.6, 1.8, and 2.0 liter varieties. I'm not sure if the RWD transmission bolts up to the FWD blocks though.

 

The FWD bluebird 1.6 liter CA16 was rated a 6.8L/100Km city driving, which equates to 34.5mpg. Though it's a bit lighter than a stock 240Z at 2182 pounds. But still, 40mpg should be EASY to see from that engine. Only issue is that it only makes an anemic 78hp. Still probably more fun than a CRX HF...

[(goldfish)]

I would be looking for a long stroke engine.

 

A current EFI system like MS is fast enough to change A/F and timings to run the super lean cruises and not det. under power. And there are EFI's out with even faster processors.

 

As stated the S30 has not so good aerodynamics, maybe the later S130 ('79-'83) would be better. It's pretty well proven that they are not really heavier than a later 77-78. But it would depend on what driving speeds are more common for you, city or highway?

[seanof30306]

I would be looking for a long stroke engine.

 

A current EFI system like MS is fast enough to change A/F and timings to run the super lean cruises and not det. under power. And there are EFI's out with even faster processors.

 

As stated the S30 has not so good aerodynamics, maybe the later S130 ('79-'83) would be better. It's pretty well proven that they are not really heavier than a later 77-78. But it would depend on what driving speeds are more common for you, city or highway?

 

Long stroke for the torque?

 

My only experience with aftermarket EFI is systems for American V8s; Accel DFI, F.A.S.T., etc.

 

The issue with those is expense; a bare minimum of 3 grand. Are the better aftermarket EFIs appropriate for this project that expensive?

 

Most of my daily commute is highway, however, this project is clearly a compromise. if maximum mpg was the only criteria, it would be much simpler (and cheaper!) to buy a crx or geo metro. The idea is to have a hypermiler that looks so good, and feels like you're strapping into a fighter cockpit every time you get into it.

 

Also, since we're going from a 6 cylinder to a 4, we'll be able to close off some of the air intake area in the nose without risking an overheating problem. From what I've read, that (along with an air dam) will do a lot to improve the aero, won't it?

[seanof30306]

Cruidin at 20:1 would probably get worse milage than 15:1 unless it was a lean burn engine ( Honda) designed to run at that. .

 

Looking at your sig, you clearly have quite a bit of expereince. I certainly didn't come on here to be argumentative, and this is really off-topic anyway, but I just think that is wrong.

 

If you ran a car on a set course, at a constant speed and rpm, you would use a certain amount of fuel. If you ran that course again at a leaner AFR, but maintained the same speed and rpms as before, you would use less fuel.

 

The leaner you make it, the less fuel you use, everything else being the same. The challenges are the mechanical limits each engine design represents. Once you reach those limits, it's not generally a question of running poorly, it's a question of damaging the engine.

 

Honda's lean-burn engine? Which one? The Civic was introduced in the 70's with Honda's first lean burn engine, the CVCC (Compound Vortex Controlled Combustion). The name Civic was actually derived from the name of the engine. The CVCC burned fuel so efficiently it could pass all US emissions requirements (even California's) with no catalytic converter, air pump, etc. Honda didn't begin putting cats, etc. on cars with the CVCC engine until the US governement made them after US automakers complained that not having to put expensive pollution controls on their cars gave Honda an unfair pricing advantage.

 

Honda's latest lean burn technology, which goes as high as 22:1, uses very high speed PCM processors to ensure ultra-precise fuel metering, a linear air-fuel sensor, and a swirl port combustion chamber design which causes the mixture to be richer nearest the spark plug tip, and leaner further away.

 

As for cruising at 20:1 and then hitting a slight hill and having catastrophic detonation, that's just not true. You don't get deto during light load. Regardless, the hill would add some load. You would come out of the cruise bins and fuel would be added, if anyone one with half a brain tuned it right. No difference than cruising at 15:1 ( or whatever) and 42* timing at 60mph and then hammering it with 30 psi.

 

Load is absolutely relevant. If you were standing straight up, and I handed you a bowling ball, you'd be able to hold onto it with no problems. If you were bent at the waist and leaning over as far as you could, arms outstretched, though, and I handed you that same bowling ball, you would fall over. I could hand you a bowling ball half the weight of the one I handed you when you were standing up straight, and over you'd go.

 

Leaning the fue mixture out does essentially the same thing to your car, "stretching it out", so to speak, making it much more vulnerable to being affected by even light loads. The leaner the mixture, the higher the combustion temperatures, and the more easily you find yourself with detonation. At some point, you can lean a mixture out so far that there's detonation under no load at all. The closer you are to that point, the more vulnerable the engine is to a sudden change in load. If the processor isn't fast enough, you've got trouble. This is ascerbated by the knock sensor. Older ones, like the ones on the GM TBIs I'm referring to, are very sensitive to false positives; reading valvetrain noise, etc as detonation. A cam, rocker arm, etc change often requires the knock sensor sensitivity to be turned down, creating a situation where the FI system's ability to react to the sudden change in load is even further reduced.

 

 

Now all my experience with FI tuning has been with GM V8s, but I can absolutely tell you that a GM V8 with a slow 7737 processor, the stock knock sensor and iron heads can absolutely experience catastrophic detonation when running A/F ratios greater than 20:1 and subjected to sudden increases in load, I've helped tear two of them apart.

[RedEvilrps13]

What models/years were available in the us with the RWD SR20DE?

 

to my recollection, the only USDM nissans to have an SR20 of any kind were the NX2000 and the Infiniti G20.

 

there were no RWD USDM SR20DEs, and unlike the CA18DET, you cannot rotate it 90 degrees and make it a RWD engine. Same goes for KA24e/des.

 

you'd have to go JDM if you wanted one.

 

in all honesty, why dont you just go buy a sub-base model CRX?

 

i mean its a bit weird to buy a sports car to be a "hypermiler" or whatever you want to call it (aka grandma driver)

 

just my .02, which is some countries isn't worth that. lol

 

ps.why the hell is there a special name now for someone who wants good gas mileage?

[seanof30306]

to my recollection, the only USDM nissans to have an SR20 of any kind were the NX2000 and the Infiniti G20.

 

there were no RWD USDM SR20DEs, and unlike the CA18DET, you cannot rotate it 90 degrees and make it a RWD engine. Same goes for KA24e/des.

 

you'd have to go JDM if you wanted one.

 

in all honesty, why dont you just go buy a sub-base model CRX?

 

i mean its a bit weird to buy a sports car to be a "hypermiler" or whatever you want to call it (aka grandma driver)

 

just my .02, which is some countries isn't worth that. lol

 

ps.why the hell is there a special name now for someone who wants good gas mileage?

 

I thought the whole concept behind hybrid z was anything goes. I wasn't aware of the fact that some swaps are approved, and some are not. Please forgive me for daring to think outside the box.

[RedEvilrps13]

LOL oh relax will you? it was a joke. careful, the internet is serious business. :lmao:

 

i love how out of all the info i dropped, you paid attention to that part of it.

 

i was partially serious about the "hypermiler" thing. what's so "hyper" about it?

[seanof30306]

LOL oh relax will you? it was a joke. careful, the internet is serious business. :lmao:

 

i love how out of all the info i dropped, you paid attention to that part of it.

 

i was partially serious about the "hypermiler" thing. what's so "hyper" about it?

 

I didn't come up with the name, dude. That's what the people who do it call it.

 

I can tell you there's a lot more to it than driving like a granny.

 

The concept I'm batting around is having a gas miser daily driver that is:

 

a) gooooood lookin

 

cool

 

c) fun to drive

 

d) (most importantly) fits my 6'5", 250lb frame.

 

D. Is the reason I was originally thinking about an LSX Z. Even though I've fabricated lower seat brackets that place the seat further back than stock, too, I still don't fit my Firebird. After a lot of research, I've found the early Zs are the only sports cars that I do fit in.

 

With where the price of gas is, and where it's going, I've decided to think about going in a different direction.

[Daeron]

RedEvil: hypermiling is another term for a change in mindset that the American public needs to adopt, or risk being killed off like the dinosaurs. It is more than "just" trying to get better gas mileage, it is about reducing impact. I won't say any more, but anyone who thinks that this approach to automobiles is "just" anything needs to re-evaluate their worldview IMHO.

 

 

Sean: Aftermarket EFI is NOT a "minimum $3k investment." Megasquirt can be purchased and set up on any engine for less than that, even if you are totally electronics-dumb and have to buy a fully assembled kit. $3K should be enough to get MS, Accurate Injection ITBs, a weber manifold, and anything else needed to install on an engine out of a 510 if you wanted to go so antique, and it is far faster than any of the 80's OEM systems of ANY stripe.

 

That being the case, I am still stuck on the idea of grabbing an L-series or Z series 4 cylinder of choice. The longblock has proven its potential for economy.

 

To get maximum MPG out of any engine you will need to be running the aftermarket EFI of your choice; some reading in the various subforums can acquaint you to the options you have and their relative cost, but I use MS as a baseline because it is by far the cheapest. Sequential injection seems to be an important point for you on this; I do not think MS can run more than two injector drivers (usually just run one on a Z but I may be wrong?) but if you ARE married to the thought of sequential injection then you either need a very recent engine with its OEM FI, or aftermarket engine management....

 

Recent engine w/ OEM sequential injection:

Pros:

Easy setup of longblock in running, economical configuration

 

Cons:

Find a transmission

Find complete engine

Mount the longblock

 

 

 

L/Z-series four cylinder:

Pros:

Easy to mount

Easy to find wide variety of gearing in any number of transmissions, established knowledge base on relative strength of various drivetrain components (thinking of possibly going with a lighter, 510 rear axle there)

Basically, its virtually OE to the vehicle in many regards.

 

Cons:

Need weber intake manifold with ITB injection

Need Aftermarket Engine management

 

 

One of the old Nissan "cons" listed (EFI management) is a virtual requirement of ANY alternative engine, and any other alternative engine would come along with the same drivetrain and mounting cons as the "recent sequential injection" above. The other "con" of the L/Z series, the intake and injection hardware, is merely a cost factor. Are you up to throwing some coin on some toys for this? The cost would be offset by other savings and benefits listed in the "pros" that only a 70s-80s Nissan engine can afford you.

 

 

I do think that a JDM RWD SR20 would be a great option. Many RWD 4-bangers would be just as good... but almost ALL of them (if I am not mistaken) were batch-fire injection from OE, which means that almost anything you put in a hypothetical hypermile Z would need aftermarket EMS. To me, that is the biggest objection against an old engine that only ever came carbureted.

[OlderThanMe]

there were no RWD USDM SR20DEs, and unlike the CA18DET, you cannot rotate it 90 degrees and make it a RWD engine. Same goes for KA24e/des.

Not entirely correct...

Someone did make an adapter to attach a FWD SR20DE to a L series transmission. It used a 3/8" plate between the motor and tranny and didn't have to modify any pieces...there is enough length on the L series tranny input shaft to make up the difference in clutch splines and still have full engagement.

[johnc]

RedEvil: hypermiling is another term for a change in mindset that the American public needs to adopt, or risk being killed off like the dinosaurs. It is more than "just" trying to get better gas mileage, it is about reducing impact. I won't say any more, but anyone who thinks that this approach to automobiles is "just" anything needs to re-evaluate their worldview IMHO.

 

You want this thread closed and tossed into the Tool Shed?

[seanof30306]

You want this thread closed and tossed into the Tool Shed?

 

John,

 

a) what about that would cause the thread to be closed?

 

clearly, you have a lot of experience with fabrication and S30s in general (that super lightweight front suspension upgrade is AMAZING!) and swapping in SR20DETs. Where would you weigh in on what the best choice for an Eco-Z might be?

 

c) would this thread be better placed in the 4cyl forum?