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7/17/08 3:36 p.m.

I have an 65 AH sprite, non-bugeye, and the engine is a little underpowered from the factory, I think she's pushing 80 or so HP, its a 1098cc 4 cyc inline engine. I'm trying to decide if I wanna throw a honda 4 in it, or perhaps a v8. I know that the v8 has been done before though.

Whatever I decide I'm gonna through a cage in it, because its soo light an I'd prefer not to die while driving it. I'm looking for a daily driver and occasional autoX whip, and when I say occasional I mean maybe once a year at most.


slefain Dork
7/17/08 3:40 p.m.

Miata drivetrain with carb swap.

Wow, the answer really IS Miata, even if the whole car isnt' needed!

maroon92 SuperDork
7/17/08 3:41 p.m.

I would go with a GM Ecotec engine.

should be fun, and seems to be unkillable

Evan_R New Reader
7/17/08 3:58 p.m.

I believe all Honda 4's, excepting the S2000 ($$$), are reverse-rotation engines. Making one work in a RWD platform is almost out of the question.

Probably the easiest solution is a simple upgrade to the 1275 engine.

Jensenman SuperDork
7/17/08 4:05 p.m.

Heck, no. Go Rotary!!!! Get a 13B, fabricate a 'mustache bar' engine mount bracket, drop it in and hang on tight! ~145 HP in stock form, with a big carb and open exhaust ~185 HP. Fuel injected with free flow exhaust and the right programming etc ~200 HP.

thatsnowinnebago GRM+ Memberand New Reader
7/17/08 4:20 p.m.

Hartley V8?

EricM Reader
7/17/08 4:23 p.m.

Get a 1.3 from a Suzuki Swift Gt and use a transmission from a Samuri, they weig less than waht is in there now.

Dual carbs on the motor, good to go.

ddavidv SuperDork
7/17/08 4:44 p.m.

Rotary, Suzuki or 1275 A series are all good choices. You might be able to get a Toyota 4AGE to fit too but it will be more work. I've never been impressed with the V8 swaps; they always look like a deathtrap and with such a short wheelbase and flimsy chassis I think you're asking for disaster.

Go peruse the British V8 swap web site. They have a lot of swaps that aren't V8s as well.

Tommy Suddard
Tommy Suddard GRM+ Member
7/17/08 4:46 p.m.
Jensenman wrote: Heck, no. Go Rotary!!!! Get a 13B, fabricate a 'mustache bar' engine mount bracket, drop it in and hang on tight! ~145 HP in stock form, with a big carb and open exhaust ~185 HP. Fuel injected with free flow exhaust and the right programming etc ~200 HP.

Nobody is crazy enough to put a 200 hp+ Rotary engine in a small British car!

EricM Reader
7/17/08 4:54 p.m.


That appears to be how it is done. Suki G13b Motor and stuff.

After looking at that, I am looking for ANYTHING I can put the G13b into.

Brust New Reader
7/17/08 4:54 p.m.

There are many options, but few fit well, and even fewer are done well. I put a toyota 4age in my 69 Midget (sprite's twin if you weren't aware). You'll want to stay on the small side engine-wise if you want to make it work well. I'd go for lightweight and here are my favorites in order: Suzuki swift aluminum 1.3 twin cam with samurai trans tie: 4age 20v Miata 1600

A distant 4th would be the rotary for a couple reasons: -they run hot and we don't have much room for a big radiator- also the car's interior is hot enough on any given day from march to october that you really don't want much more -they run loud and we don't have much room for muffling. My 4ag is loud enough, and I understand that rotaries are pretty loud themselves -Fuel efficiency is abysmal. We only have 6 gallon gas tanks. I get 35 mpg out of the 4ag and still struggle to break the 200 mile mark. Rotaries can get anywhere from 15-mid twenties, which really limits what you can do with them range-wise.

I've got a website with info on my build: www.home.earthlink.net/~roethler

A guy named trevor has one about his Miata based build: www.the-mite.com

Another guy with the suzuki engine www.ado13.com

I did the 4age 20v because pound for pound it offered the best performance- engine and transmission together weigh about 300lb and it puts out 150 hp roughly. Stock 1275 weighed about 260 lb, so it wasn't a weight gain that couldn't be overcome with some lighter bodywork, relocated battery etc.

Good luck, it's been a fun ride.


John Brown
John Brown GRM+ Memberand SuperDork
7/17/08 4:54 p.m.

3.5L Shortsar V6

ignorant SuperDork
7/17/08 5:01 p.m.




Rev till you puke... then go 2krpm more...

MCarp22 New Reader
7/17/08 5:08 p.m.

I'm surprised nobody has mentioned the SR20DE! It's all aluminum, so it's a good bit lighter than those ugly lumps of iron from mazda or toyota, it's 2L so it makes real horsepower, and it's got aftermarket out the wazoo. Everybody wants the DET turbo motor for their drift car, so the RWD DEs are incredibly cheap.

What's not to love?

oldopelguy HalfDork
7/17/08 5:13 p.m.

I'm using the 3-cylinder Suzuki 1.0L with a Samurai trans in my Midget, but I'm building it for economy and not hp. Mine's a bit lighter than your standard Spridget, though, with the Arkley kit, so it should still be decently fun to drive.

ae86andkp61 GRM+ Memberand New Reader
7/17/08 6:50 p.m.
MCarp22 wrote: It's all aluminum, so it's a good bit lighter than those ugly lumps of iron from mazda or toyota

I wouldn't be so sure! The 4A-GE is a thin-wall cast iron for the block, and has a simple (light) valvetrain when compared to the SR20....add in the fact that the RWD Toyota T-50 transmission is tiny and lightweight compared to the Nissan 5-speed and the results are surprising.

This page claims 155 kg (340 pounds) for the 4A-G/T50 as fitted to the car, less exhaust manifold, and 183 kg (a smidge over 400 lbs) for the Nissan RWD SR20DE with transmission complete as fitted to the car.


Now...I didn't create the above webpage, nor did I weigh both drivetrains, but the numbers seem to be in line with what I have experienced and heard elsewhere. I'd be happy to stand corrected if anyone has better information to share. The factory Toyota exhaust manifold is cast and adds a bit of weight, but that is what headers are for. :D

The Nissan does have availability, aftermarket, and displacement/torque going for it, and could be a good option if you come across one for cheap and can make it fit. I'm not saying the SR20DE is a bad choice, just saying don't assume iron block automatically equals heavy.

amg_rx7 New Reader
7/17/08 6:55 p.m.

Another vote for a nice13b rotary. If you get a fuel injected one, you can Megasquirt it too. :)

Jamesc2123 New Reader
7/17/08 7:05 p.m.

All d and b series (civic, integra, etc.) honda engines are reverse rotation, while the k series (rsx and some others) is normal(?) rotation. It makes lots of power but is relatively heavy and if i were interested in power at the cost of weight and perfect balance i would go all the way and put a v8 in it.

There is a bugeye sprite right now at historic smalley's garage in Watkins Glen that i was told has a small block chevy in it. I drool at it every time i drive by...

Greasyman New Reader
7/17/08 7:15 p.m.

If you have only basic mechanical skills and have never done something like this before I think you should go with the simplest and most straight forward swap you can find. One that has a kit available would be ideal. Even a simple swap is a complicated job, so why not make it easy on yourself, you don't want it to be so hard all the fun goes out of it. I'm sure some research on the internet will pay off.

mad_machine GRM+ Memberand SuperDork
7/17/08 7:16 p.m.

I think the Honda K series would be the way to go.. lightweight, high rpms (so un-british tractor like) and nearly industructable if you do the maintance

cwh Dork
7/17/08 7:17 p.m.

I saw a very interesting Spridget at Tex Racing, a NASCAR shop in NC. Beautifully done turbo Buick. Looked factory. I wonder what it felt like with the hammer down.

aeronca65t New Reader
7/17/08 8:07 p.m.

Your 1098 cc engine makes 59 horsepower.

A nice 1275 "A" series engine is ideal for these cars and bonus you get to keep the wonderful ribcage trans. A 1275 built to about 90 HP is a wonderful thing in a Spridget. Plus you won't have to hack the trans tunnel out and make it bigger (but if you do choose to go that route, hope you have teeny-tiny feet).

The vast majority of engine-swap Spridgets that I've seen have ended up not being finished......and another Spridget is lost in the bargain.

Storz HalfDork
7/17/08 8:18 p.m.

Sportbike motor?

MCarp22 New Reader
7/17/08 8:28 p.m.
ae86andkp61 wrote: just saying don't assume iron block automatically equals heavy.

I was only teasing to bring light to another option. :)

ae86andkp61 GRM+ Memberand New Reader
7/17/08 9:14 p.m.
MCarp22 wrote: I was only teasing to bring light to another option. :)

I see.

Was there much variation in the RWD SR20DE over the years? Any particular version/year/donor model to go for?

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