Best budget/MPG engine for RWD project
 

I'm going to put together a Lotus 7 replica or similarly light RWD project car and am sorting through engine options. I'd prefer something that is relatively common (so newer than 1990.... newer than 2000 would be even better) and affordable. I'd entertain the idea of <60-80hp motors but am looking at some feasible 130-150hp options that would be much more entertaining.

I'd like to focus on gasoline engines right now, I know a VW TDI 3 / 4 cyl would meet all of my goals but unless I find a steal on one, it's going to take a long time to pay off. I also believe that CNG is something that I'll be able to use locally in the near future and I think once that crazy-cheap fuel cost is factored in, the diesel loses most of the advantages it has.

Whatever I pick, if necessary I'd run it on standalone EFI and have no problem adapting whatever motor it is to my RWD longitudinal transmission of choice.

I have Datsun 70's model A12/A15 motors and parts and could stick multiport injection on one, but don't think it's going to stretch the economy too much and will certainly not get past 80-90hp without adding a turbo... and replacement parts have gotten higher.
Suzuki/Geo Metro 3/4cyl are interesting but getting to be a bit long in the tooth.

Honda: L series, R series. Certainly getting cheap enough and spin the correct direction. Then I see that K motors have come way down in price and I know I could take the project in another direction by going gonzo power with one of those. So right now my favorite seems to be the R18, the simple Vtec on it and it's psuedo-atkinson cycle really seem promising.

Turbo Japan Kei car ~667cc engines could work, but USA availability is certainly an issue.

If there were more BSFC charts (one of the best collections I found was certainly here on the forum! Thanks!) I would have more to debate with but for now, I'm open to more thoughts and suggestions!

I would use a Honda D15z1 from a Civic VX or a D15 from Japan, it's pretty close to the D15z1 only it has the 3 stage V-tec head and a different intake but I think it is otherwise pretty close to being the same engine block, the D15z1 is around 92hp at 5,500rpm and the D15 is said to be 128hp at 7,000rpm.
These engines tend to last 300,000 miles, unlike some of your other options, this also makes them cheap and common.

Honda D, B, H, etc.... older engines spin the wrong direction for me to hook to a regular RWD transmission. :(

1.6 from an early Miata? Parts availability is very good, especially weight-reducing and performance enhancing mods if you want more than the original 115 horsepower. Online community is very helpful as well.

The NA Miata, with a .38 Cd, was rated at 30 highway (old number), so it seems like the potential is there for some very good mileage, especially in a light car with a higher-geared differential &/or bigger diameter tires.

1.8 from the NB Miata makes ~140hp stock, returned the same mileage rating.

The Miata transmission is a real sweetie as well, short throws & good feel. 6-speed is available on the some of the later ones.

Certainly a possibility, and I do like the gearboxes. (Coincidentally my gearbox of choice could be turbo mazda rotary) I do think it's going to be behind in MPG compared to like a Honda R18 and for no major gains (except that it's ready to go RWD, which is one)

I may inject one of the old datsun motors and see where that gets me, if they got the best epa highway mpg for the years they were made, certainly I could inject it and get a BIT better? But it's still going to be turd slow (<70hp) unless it sprouts a turbo.

Have you considered motorcycle engines?

If that's not where you want to go, maybe GMs Ecotec line. I believe any Ecotec engine will mate up to the RWD trannies in the Solstice/Sky and this would give a wide range of sizes/performance to choose from.

Look to small pickups? 4cyl out of an S10, Ranger, Tacoma, etc. Very common and inexpensive.

Nissan 240SX motor?

Suzuki sidekick 16v 1.6 engine. Can do 15psi boost with very little mods. I could hit close to 30 mpg keeping up with traffic with stock tires and stock 5.12:1 gears, revving high and the tracker / sidekick is not very aero dynamic

knew a guy to run 15s with stock drietrain and 33 inch tires with a turbo

The more I think about it, the more I think that anything >2 liters is going to have to be a very well designed motor to do anything near what the honda R18 does. Since it has very high compression yet has the economy cam profile to reduce pumping losses, it should sip fuel like a motor even smaller than a 1.8 at cruise. Yet still makes ~140hp! If some other great BSFC numbers come up or if someone can highlight some great highway MPG feat of some engine that suggests that it must be approaching the best of the best BSFC.... That's what I'm looking for.


I'm not going to run a motorcycle engine. I'll keep the ecotec in mind, as I certainly can pick up a bolt on transmission for it but I still think the R18 honda is going to get better fuel economy. Once I get to play more with direct injection gas motors, the Ecotec and Mazda stuff could be ones that I would deal with in a swap scenerio but right now they're a bit pricey and I'm afraid of parts costs.

The later Ranger's mazda MZR motor is one I've thought some on. Aluminum block and modern fuel economy oriented cylinder head is a plus and I believe I could run a smaller 2.0 from a car. I don't think the S10 stuff is going to eek out quite the fuel economy the more modern designs will. I've seen what the tacoma 2rz/3rz motors can do, big big power under boost, but they don't seem to be as economy oriented as the other newer car-designed motors.


I have a bunch of 240SX stuff but they are certainly not too exceptional on fuel economy. Giant stroke "truck motor" .... If I get some parts together and the project seems to be moving along quickly, I may actually drop the new drivetrain into an extra 240sx I have instead of the older lighter car. I'd focus more on the 240sx if I had a taller geared diff for it as I know the aero is pretty good and I could take a bit of the weight penalty considering how much less work it will be to get finished than the older car!

If I run into one.... I'd certainly like to give it a try over the older 3/4cyl Suzuki aluminum block motors. Looks like they make ~95hp to begin with? Not bad, wish it made the ~120hp of the 1.8 liter version. At least it should be on the very light weight end of things like the earlier ones, and 1.6 liters is nice and small.

An Insight I engine without the battery ?

Lotus 7 is very popular with the Zetec 2.0L, and I say that not just because I have one in my ZX2. In that light of a car, 50+ mpg would be easy with better gearing.

Suzuki G-series, the 1.3 DOHC makes 100BHP, add a 1.6 block from the Samurai and you could get 120BHP. There are also RWD boxes from the Samurai but I'd recommend getting an adapter to fit the tranny of your choice. They're efficient, lightweight aluminum at 180lbs or so, and available from '86-2001, from carb to multi-port EFI. They also have a bit of an aftermarket and some support at teamswift.net, and they are global so it's not just the piddly US fans.

I like most everything I see with them but availability is slowing me down. Not that they're scarce, but I've ran into some CHEEEEAP other options...

Yaris/Echo/Prius motors, CRAZY light weight, ~100hp (in the non prius version) and I see them for $250-$500 all day long, most of them are very low mileage and as many as there are I'm sure I can get a cheap one to get going and then get a cream puff to swap in later. The intake manifold will require a lot of re work so it's not back into the firewall. I don't like the VVT so much but since the prius doesn't have it, I bet I can lock the cams at some point using Prius bits if need be. Of course the whole CARS are cheap when wrecked so I could possibly be talked into using factory computer instead of DIY. Factory TRD supercharger was offered so I'm sure if I got frisky down the road I could lightly turbo it to beat the ~140hp Honda R18 motor (my current favorite) and still siiiiiiiip on the fuel.

Hope to secure a broken one within the next week to start mock up on. :D:D

Honda Civic engines from the late 80s and early 90s might also fit the bill if you're looking for light dependable cheap engines that make about 100 HP. The D16A6 in my 1990 CRX Si was rated at 108 HP stock, and I think 99 lb-ft of torque? The gearing is way too low for good economy, but the motor is decently thrifty.

And the CRX HF ran a D15B6 (?) good for ~65 HP, and with tall gears it was a serious fuel sipper.

-soD

I certainly like them and would have been playing with them in an application like this years ago... but since they spin the opposite direction to 99% of the rest of engines out there, that gets to be a bit of an issue! :)

$250 would be overkill for a G13B. Most people disregard them and they're throw away cars/engines to most people so they would have even less market value than a Toyota engine. And there's no VVT to work around and you could pick if you wanted a preOBDII or post OBDII :thumbup:.

Good luck getting a complete used car with the market the way it is :mad:. A complete/partial engine would probably be the cheapest option at this point since it would not have the intrinsic value of a vehicle attached to it. I've seen normally $1500-2000 foci going for 1.5times to twice their KBB value in my local craigslist. Your market might be better than mine if you can find a $500 non-running but otherwise complete car!

Godspeed.

the sidekicks these engines came in are all primary drive to the rear, also there not all 4WD there are some 2WDs out there.

as a reference, my hard top 4D, manual trans, with 5.12 gears gets about 30mpg at 55 with just easy eco mods. also i live at 1,000' and every where i go is at sea level:(

the 2WD trans is so lite i can carry it over my shoulder a fully dressed engine i could move by my self so i know its under 200lbs for the engine and trans.

off the top of my head i cant think of any other engine thats 1.6L 16V in 1992 "first year it was sold" that has 95hp in a 1.6L 16V EFI engine.
this engine has a older model it was a 1.6L 8V TBI and is favorable for being used in autos that need lower rpms.
where as the 16V likes to rev and seems boged down under 2,000rpms in the 3,000lb suv even with the 5.12 gearing.

that's what i would do, that or a Nissan SR20. my first car was a 1981 Datsun 510 Hatchback, and the 4 banger (Z20S) in that thing pulled like nobody's business, i got 24-25 MPG average on a regular basis (usually loaded up with my buddies for a road trip, likely around 2900 pounds total)

flip the rear differential, unless you're going to use an auto it shouldn't be too big of a deal

Flipping the diff means that the "wrong" rotation is still going through the transmission and drive shaft (or whatever drive mechanism). Running a transmission "backwards" is not a good idea, unless you've got one that is designed to survive spinning both ways. (I think one that uses all straight-cut gears would be OK, as long as there weren't any oiling concerns.) The helical gears in the transmission will be pushing on stuff they're not designed to push on, leading to accelerated wear pretty quickly.

You'd be OK if there were a RWD Honda that hooked up to a D-series engine; you could use the transmission from it. But I don't know of any such animal.

I would doubt that anyone makes reverse-rotation cams for the Honda engines, either.

One possibility might be to use the whole drivetrain (engine, trans, axles, etc.) and move it to the middle or rear of the car. But that only works if you have significant flexibility about packaging things. If your layout is already set for front engine, that's a no-go.

-soD

Would the transmission out of an S2000 work?

[Edit: Nevermind, that motor apparently turns the "right" way.]

Sorry, yesterday was a long day, i didn't even think about thrust bearings and gear types.

if it wasn't so expensive i would say get one of these, though the power is much lower than you are looking for

Kohler Diesel Engine — 1028cc, High Speed Open Power with Group 8 Interchange, Model# KDW1003-1001 | Diesel Engines | Northern Tool + Equipment

Have you considered some of the old pre ecotec gm 2.2L that put out 120hp got good milage had a friedn with a 97 cavalier that got 6.4L/100km out of the 5spd and the thing had 400,000km on it. There is also the GM D-Tech Motor it is korean out of the Chevy optra/ Suzuki Reno the odd thing is that in Canada the Optra is detuned to 119hp and in the US the Reno is at 127hp. If you want a bit more grunt there are the Celica 1.8L non GTs motor rated at 140 or the GTS motor which can be found in the XRS corolla which puts out 180hp. If you wanted you could try and track down a Civic CX motor. There is also the GM 2.4L out of the Sunfire GT/ Cavalier Z24 that puts out 150hp and 155lbs or torque. There are a few domestic options with Chrysler and Dodge with the neon engins ie the early 2.0L that puts out either 136 or 150hp both can be found relativly cheep.

Unfortunately, that is another older Honda motor, which spins the "wrong way".

-soD

Yes, I've considered especially the multiport 2.2. Lots of those GM motors have EASY RWD trans options (except for the quad4 but just add a couple extra $ ;) so I do like them... but a bit on the big side, displacement wise. I do have a fiero sitting and if one turned up for the right price, that would certainly be an easy 35-40++mpg on the highway and almost zero fab work required. When I had a fresh drivers license I racked up many miles between the fiero and a 2.0 cavalier so I do have some experience there.

The celica 1.8 non-GTS motor is also a good candidate. I think I'm "settling" on the echo/yaris/XB 1.5 because of cost/availability, but I can also see building more than one car. :)

The parts have started to come in for me to test out the datsun A15/5 speed set I have... into the S13 240sx hatch. Need to extend the shifter back about 6". Transmission slip yoke is on the way, and I scored one of the oddball mitsubishi MPFI intakes that with a bit of massaging (spacer plate plans have already been sent to the water jet man) will fit said A15. I more want to try this motor now out of principal since I've had 2 people say "how fast will it go, 60 max?" Hehe if I have 10-25 more HP than the gas motor in a 1g Prius... I think it'll be just FINE on the highway, once it gets there!

Thinking if the A15 gets really good mileage once it's injected, I can drive it while I work on the yaris setup. Then move it over into one of the "toys" and stick the yaris setup into the 240. I'm optimistic that the yaris motor in a base 240sx hatch with removed PS, no AC, etc might end up being even lower in weight than a Miata.... suggesting that it won't be that unpleasant to drive as far as acceleration goes.

Bought a set of ~3.5:1 gears to stick into an extra S13 240SX diff. (4.08 are common/stock) Good for a high-torque engine swap should I do one at a later time... and if the little motor I stuff into this one seems like it can pull the load with that much more gear, I'll give it a try.

In my opinion this has given my S13 a firm advantage for the MPG project over doing the same engine/trans swap to the RX-7. :)

The Honda S2000 spins the right way. Even comes with a RWD transmission - the transmission is big though. I am sure you know of this site already, but have you checked LocostBuilders There's a ton of useful information there..

If you want good fuel efficiency, the Super 7 is a pretty horrible choice though. It has some of the worst aerodynamics you could imagine, and would need quite a bit of redesigning to improve that..

s2000? He said budget.

The F20/F22 in the S2000 are certainly nice power wise... but far from budget :( A K could be as capable/more capable and better priced, even after the work to mate it to something RWD. In an interesting coincidence, S2000 owners are swapping K motors into their cars for more power / even better parts availability. :D

I'll certainly poke around locostbuilders. Thanks! I've been lurking at LocostUSA.com &bull; Index page for years. ENDLESS fabrication Pron..... :)

Yes, the aero is usually bad on a 7.... but can be fixed. My first short term goal is getting one of these swaps into an aero friendly 240sx or RX-7.... Then one into either my datsun 1200 or a fabricated locost.

Theres a place in texas that has brand new fully dressed 1996 ford aspire 1.3 motors.

i think that would be a great choice given the block and bellhousing bolt pattern is identical to the 1st gen mazda miata.

link:

NEW 96 97 FORD ASPIRE 1.3L COMPLETE ENGINE ASSEMBLY

The Aspire had a Korean engine for one generation so it would be a gamble until you knew that it was the Mazda version, plus if I remember correctly it was always a cast iron block. The Korean engine has no aftermarket that I am aware of, and in this case you would want the Mazda variant which is just a smaller version of their 4 cylinder engine family at the time.

It's true that the KA and even the SR are heavy engines so I don't doubt it could be light. The problem would be sourcing a cheap Yaris engine.

I'd like to get a 240sx hatch and put a Suzuki engine init because they're both light and small displacements. And then I'd built an engine for E85 but keep it a street car. I spent some time researching the G family hence why I brought it up. But right now I just need a car so I can get a job away from home. Someday I'll get around to it :rolleyes:.

Those 2.0 liter Ford Z techs might be neat. I think they use many of them in the UK's cottage industry. In a car that light it would be a rocket. Is it one of those Caterham cars ?

Lampredi Twin Cam 4 cylinder ( Fiat, Alfa, Lancia ). Best designed 4 cylinder in the universe, heck, everybody copied it. Bombproof, rally winner, simple, easy to get parts for, not that expensive, spins in the right direction. Put some compression into it and keep the cam timing near stock, should mpg well.

dodge neon 2.0, 132hp AND 129 lbft of torque,

dodge dakota 4 cylinder bellhousing

ax15 transmission (every 5 speeed 90s jeep) or any toyota rwd 5 speed (same thing)

neons get 40mpg pretty easy and it still has some go to it