Engine Dimensions-LSx vs. SBF vs. SBC

So I need some help. I'm kicking the idea around of a V8 swap in my Miata, and I need some dimensions to help me decide. Options are:

1) LSx-preferably aluminum, but I think I could get an iron truck motor a lot cheaper. Stock intake.

2) SBF-aluminum heads and stock HO fuel injection intake.

3) SBC-most likely an aluminum headed LT1, or at least aluminum headed TPI.

I need dressed weights (with accessories) and LxWxH. I realize I'm going to need to know a hell of a lot more about all the options, but this is just a start.

While I'm here, what's the size difference between a T56 and a T5?

I don't have any info for you but I MUST be involved in this.

I've got an empty engine bay we can measure up if need be.

Clem,

P.S. I can come get that moped this weekend...

Pick the engine you like the most (for whatever reason, preference, cost, maintenance, weight, etc.) and start in on it. They all fit. Do you want to go with a kit or are you going the DIY route?

Bryce

More than likely DIY. Options I found are:

1) Monster Miata for the SBF, which is 4 grand, but pretty nice stuff.

2) Boss Frog for the LSx, which is $1.4k for motor and transmission mounts. Unfortunately LS1/T56 is waaaay steeper than 5.0/T5.

3) ~4k for FM's LS1 kit, which is very nice, apparently.

Honestly, I'm leaning towards 5.0/T5 with homemade mounts. It's been done enough times, and there are plenty of those engines out there, as well as speed parts.

I'm thinking that with time, junkyard hunting, and some fabrication, I can do this for ~$1k plus the cost of the engine and transmission, and make it look and run like it came from the factory. Just trying to do my homework here in the beginning.

I need to learn to weld anyway. May as well go whole-hog.

Clem, Saturday is busy for me but I'll be around Sunday if you wanna come pick it up. Gimme a call.

SBF 5.0 w/EFI is only 225HP to start. The intake is large and heavy, as are the heads. You hit a wall at about 300HP that's not easily crossed without boost or dropping the factory-style EFI.

SBC's fall out of the sky and make 300HP if you look at them funny. TPI/LT1 stuff is a LOT more expensive and honestly doesn't make the power.

LSx is still the HP king but as you pointed out it gets expensive, FAST. T56 is HUGE compared to a T5 and weighs at least 100Lbs more. Luckily the GM T5 for the SBC can bolt to the back of the LSx.

I'd honestly go SBC if you want to keep it super cheap (and I love LSx swaps!). Grab a 3rd Gen F-Body T5 setup, wallop in any old 350 with a 4Bbl and go to town. It will be lighter than the SBF and make more power plus be cheaper than the LSx.

3.8L GM

1) 300 HP is enough for now. We're talking about a car that will probably only weigh 2600-2750 when done. 10 lbs/hp is more than enough to run me out clean underdrawers.

Moreover, SBF is more compact and lighter than SBC (I believe substantially so.) I need to read up, but I believe aluminum heads will be cheaper to come by for the Ford as well.

I'm wanting to go megasquirt for fuel management, but I was wanting to keepthe factory EFI intake to stay on the cheap. I don't particularly want a carbureted car. Megasquirt gives me a chance at some decent fuel economy as well...at least once I ditch the 4.10 gears for some 3.636es.

As for the GM 3.8, I considered that as well. It's compact, supercharging is easy, and they're dirt-cheap...but if I'm gonna go to all the trouble of an engine swap, then I'm gonna get the V8 rumble to go with it.

I'd look into a cammed 5.3 LSx with T5 if it was me..... I'm not positive, but I thought the LSx motors wouldn't have much trouble destroying the T5's....

Nathan

njansenv wrote: I'd look into a cammed 5.3 LSx with T5 if it was me..... I'm not positive, but I thought the LSx motors wouldn't have much trouble destroying the T5's.... Nathan

In such a light car, transmissions will hold up a heck of a lot better than in something like a piggy F-Body. You also can't get near as much rubber to the road due to tire size limitations in a Meotter. Plus, T5s are dime a dozen compared to T56s.

Bryce

I'd buy an old Camaro with an LS1. It's a lot of work no matter what you use, and I'd rather have an LS-powered Miata after all that.

Keith wrote: I'd buy an old Camaro with an LS1. It's a lot of work no matter what you use, and I'd rather have an LS-powered Miata after all that.

Not that you're biased or anything...

Not to hijack, but I'm seeing pretty clean looking LS1 Camaros getting down to around $5k. If you pulled the LS1/T56 how much do you suppose you could get parting the rest?

As far as engine cost, you can get 5.0s, TPIs (at least 305s are easy to find, the 350s are pretty unusual), and LT1s for under $250 complete with a bit of looking. The closest I have seen of the Ls type engines for that cheap were all in trucks that had engine fires (out of the 50 or so i have seen, i think a few of them at least the long block was salvagable, i cant so as much for the intake and wirking harness).

Nashco wrote:

Keith wrote: I'd buy an old Camaro with an LS1. It's a lot of work no matter what you use, and I'd rather have an LS-powered Miata after all that.

Not that you're biased or anything...

Hey, I wasn't a believer until I tried it! I didn't say "buy the FM stuff" (although I think you should), I said "I'd rather have an LS-powered Miata". I was taken enough by the result that I changed my MGB plans from a 302 to an LS1/T56.

I picked up my Camaro for $4500. I'll be parting it out later, I'll find out then what the remains are worth. There are only about a half-dozen 4th gen F bodies in town so that's going to make it harder to get rid of body parts like the big high-rise hood on this thing.

Then again, you can get a 5.0 Mustang convertible for about $100

I have a couple of 1st gen RX7s one with a SBF with all the light bits it weighs within 20lb of the original 12a.....about 350 hp

The other has a 500+ hp sbc it is much heavier, but holly hell its a lot of engine...

Chev makes mad power cheap, Ford is light and very quick, its up to you either way

njansenv wrote: I'd look into a cammed 5.3 LSx with T5 if it was me..... I'm not positive, but I thought the LSx motors wouldn't have much trouble destroying the T5's.... Nathan

That is kinda what I had planned for my 85 RX-7. Stock 5.3 + MS + T5 should be more than a handful.

I just need to get the 5.3, the MS, a kit from Granny's and enough motivation.

BTW - something I learned when I started working with the LS engines. The GM engine management is well and truly cracked. You can program it and return OBD-II codes. Can't do that with any aftermarket ECUs. No need to go MS on GM stuff.

Alright, the LSX will apparently warrant further investigation. It is tempting to have "300 hp out of the box" rather than "300 hp grenade". Honestly, by the time I build a SBF, I may be money and frustration ahead to just have a stockish LSx.

Travis, I don't know what yard you're find LT1's for $250, but I wanna know where it is. Around here they're more like $500 to $700 (more for the F body motors with aluminum heads).

Keith: I know the FM stuff is good, and I know you're not just a shill for them. Everything they make is high quality. But I can't afford to shell out $4,405 just for the conversion kit.

So yeah, I still need dimensions and weights for the motors if anybody has them. I seem to recall someone posting a spreadsheet long ago that had weights for a whole bunch of performance engines. Anyone else remember that?

If you can weld, you can make your own conversion stuff. That's how it's made!

You'll find, when you do all of your research, that the FM parts aren't really much more expensive than anything else on the market. To get the same number of parts from Boss Frog will also cost you more than $4k - and you'll end up with more front weight due to the forward position of the engine. You quoted Martin's kit at $4k as well. So I'm not sure that the usual knee-jerk "FM is so expensive!" cry is justified here. It's just that we're up front about the costs.

Keith: When is the Flying Miata turbo LSX kit going on the market? I mean, if 330 HP is good, 550 should be better, right?!

Seriously, your price/quality/service relationship seems about right. The interesting thing about the Miata specialization is that you can take a $1k car and throw $7k worth of go-fast goodies at it, which is kinda unique because other than veedubs, one typically throws that kinda money at something with a much higher price of entry. So you get cheapskates like me with two $400 Miatas, looking at spending more on that just for tires!

If you have a problem with spending $7k on a $1k car, get yourself a 2004 Mazdaspeed or even a brand new 2010 MX-5. They're still worth something. Unfortunately, new parts don't depreciate, so we can't really lower our prices just because 20-year-old ratty Miatas are available. Look at it this way - for $8k, you can have a crazy quick NA Miata, or you can buy 2/3 of a new Kia Rio!

No plans for a turbo kit. Not when you can buy a 480 hp LS3 crate engine with a two-year warranty for $6k from GM! With the three LS cars we have under construction at FM right now, that's the engine in the slowest one. Yikes. Making power with this engine is so easy you can pick up 50 hp almost by accident.

I'll see if I can get dimensions and weights out of one at work.

I'm not saying the kits are overpriced. I would love to be able to afford the FM kit, or the boss frog kit (which as you said, is less complete than the FM kit). Unfortunately, I'm on a shoestring budget.

I believe I can do this for under $2.5k, and retain a car with near-factory driveability, that doesn't look like some wackjob with a cutting torch and a welder just decided to drop a V8 in the lightest car he could find, just because he could. (I don't have a cutting torch. Other than that it's pretty accurate.)

Because my budget is so low, I just don't think the LSx is in the cards (at least not an aluminum one). I've looked around. Minimum outlay for the engine will be in the $1200 range, 300 for a T5 setup, etc. etc., and by the time it's all said and done I don't have any money left to make mounts/go hunting for ancillaries like cooling/ pay for exhaust.

My goal is 275 whp. That's going to be super-easy to get out of any of these motors. It should also be enough to scare the living bejesus out of me. Also, the factory 94+ rear end should survive, provided I don't abuse it. I can always upgrade power and such later.

in central in I have bought fully dressed lt1 for 100 ea. I have 3 0n the floor now .

Devil's Advocate:

SBFs are relatively cheap and much lighter but you'll need a good set of aftermarket aluminum heads (1K+) and a better intake manifold. Stroker kits are available to punch the motor out to 347 ci (with .020 overbore). Overall package size is smaller so exhaust routing may be easier. Front mounted distributor means more engine setback possible.

Balance-wise, the SBF could be the way to go. Better handling, plenty of power, easier on the driveline so lighter, smaller trans is possible, not to mention rear end life.

Jerry - Are you comparing the SBC to the SBF and leaving out the LSx? Because there's no distributor on an LS engine, so setback isn't an issue there. We put them within about 1/16" of an inch of the firewall.

"easier on the driveline" means "it doesn't make as much of that pesky power and torque"