Chango2

Hi,

Likely this is a simple question, but is there any difference in difficulty and weight re. using an LS Chevy engine vs. a Ford pushrod SB?

Thanks,

David

cvx_20

Degree of difficulty is a hard one. There are "kits" available for either, the 5.0 is actually somewhat smaller, requires a little less surgery around the bellhousing area, other than that not a lot of difference in the conversion. The 5.0 outweighs the LS, mostly due to the plastic manifold on the LS. But most 5.0's use a T5, which is lighter than the T56. Not really a lot of difference overall, IMO.

The last year for a passenger car 5.0 was 95, if your state cares about such things.

Go for a 347 stroker with aluminum heads if you're a Ford guy.

Just noticed you're in CA. Look up Monster Motorsports, the leader in Ford conversions.

Mike

charchri4

He David welcome to the party!! Yes to answer your question there is significant differences. But there is no reason to reinvent the wheel here just poke around and you will see lots of excellent threads here that address those questions really well.

It would probably be more help to you for us to turn the tables on you and ask you questions. The 4 big ones are:

What do you want to do with the car when it is converted?
What are your abilities and facilities to do this swap?
What is your budget?
What is your time goal?

Because you are in CA you get a 5th one. Do you intending to have it pass CA emissions?

With that info the community here can do much better to point out the various options that seem to work out best for folks doing what you want to do.

rugger

I don't have stock in either build as mine was small block chevy.

But, I have to ask the question "Why would you choose SBF over LS?".

The degree of complexity is similar for both. With simple and cheap LS mods there are great increases in power/tq with maintained reliability. And, with the modern fuel management combined with the T56 you can get on all of the Prius boards and talk about fuel mileage.

charchri4

LOL can't wait till Jason sees that ^^!

Tons of reasons.
SBF sounds way WAY better than the LS does and for me that was enough of a reason in itself to go Ford.

SBF is usually from a few to lots of thousands cheaper to build.

You can get by building one without owning a welder.

There are plently of people in this world that feel 300 hp in a Miata is plenty and would prefer no more.

It takes much less surgery to build a SBF than an LS and for some that is an issue.

For some they may already have a donor or motor. For the better part of a decade I had a well built 289 with 351w heads on it under my bench with nothing to do.

There are plenty of people in this world that would rather push a ford than drive a chevy! Right Jason?

And the flip side?
Existing doner could be factor with the LS too. I built an LS because I had a Camaro I could not get sold.

Larger displacement and lighter engine (but the engine trans combo is about the same weight between the 2 so no big deal there)

With a grand in cam, tune and headers the LS can hit 450 HP at the crank with out working very hard to do it.

I really like 6 gears!

I'm sure if this is really a benifit to the LS but to many the fire wall mods are not a + for the Ford. To anyone that seam welds the chassis the firewall surgury is no big deal at all.

OK honestly now that I sit down and think about it.... I have more reasons to build a ford than an LS!

Bottom line is if you have from 16000 to 20000 in disposable income lying around and want the most HP you can squeeze out of your $$ then the LS makes sense. If you are not a huge HP person and would like to stay under 10000 then the Ford is the way to go.

WolfGT

And if you go the route I am going with an even old SBF, you can avoid the computer situation all together with a carb version.

WolfGT

Oh Jim, this makes me sad. I hope that engine was gone when you did your miata because that would have been perfect. Then you wouldn't have had to rape that camaro.

charchri4

Oh you are going to love this. I found a much better home for it right under that blue and white scoop...

The car started life as a 6 cyl 3 speed and was a barn find I picked up for 300 bucks in 1985. It was barely more than a shell but the barn was in TX so she is a clean as can be.

5.0MX5

YEP, you're gonna have to post up a couple poster quality shots of the two; Miata and Mustang.

caymantrackrat

OK I have read all the posts sbf vs ls. Here's my dilemma. I have a 91 NA with no motor/trans and a new 350/350 ramjet (fuel injected small block chevy). Any reason not to marry the two? weight? front to rear distribution? I will track the car on a regular basis, so balance is very important, but I do want a/c and maybe p/s.

charchri4

Hey welcome!
Well it's a bit hard to know with out knowing what your situation is. If you have 10 grand of disposable income laying about then no I would not use the SBC for a track car I'd build and LS car. If you don't have the chops or gear to fab a subframe and all the other parts then no you should go with a kit build.

But to answer your question there is absolutely no reason not to marry them and I can think of no better use for that small block than a Miata. Sure the LS would have slightly better balance but so what? You have the engine and you have the car so put them to good use. You will learn how to drive it and squeeze the lap times out of it no matter what it is and for sure it will be more fun than the 4 banger. And if for whatever reason you get it built and don't care for it then you sell it. Put together it's worth a lot more than apart and you can always go another direction.

You might want to shoot a PM to one of our members posts that built a SBC car. His name is rugger v8 Miata Forum - Home of the v8 Miata Conversion - View Profile: rugger

This guy also did a SBC build and has a couple of good threads on it. Proguru's 327 Miata Build - MX-5 Miata Forum

Looking forward to hearing more about it. You should start a new thread where folks will see it. This thread being about a ford and all...

rugger

What is your alternative if you don't run the SBC?

caymantrackrat

Hello Rugger, we talked before, you thinking about doing a sbc kit. Anyway I guess my alternative would be to either go with an ls if I build or just buy a car already done. But I have a$5,000 motor and nothing to put it in. So take motor and car I already have add, what 10k, and a year of build time or buy a done car and have fun now? Trouble is every car I have bought I always have to change

rugger

Any kit type fabrication is on hold for me. I've sold my SBC and transmission, and I have an LS and T56 sitting in there now.

cvx_20

No reason that I can think of. The purists will say that you will ruin the balance, but they haven't really done the swap, have they? The guys who have like them, but at least one has gone to the LS motor after driving his 327 for some time.

I would make every effort to move the weight towards the rear. Don't be afraid to make room for the distributor by making a huge depression in the firewall. Or better yet, find a way to go distributorless. Surely there's a way to convert the thing to EDIS or the GM equivalent.

You might consider a five speed or even an older 4 speed. You don't really need all the gears, but you do need strength. That's the main reason for going with the T56, but they are a lot heavier. The extra weight doesn't affect the balance that much, but it is extra weight that you already don't need.

Go for it!!!!

OOps, answered a question from the bottom of page 1. Senior moment

Mike

caymantrackrat

Well I have decided to find a ls car already done or close to done. If I build my miata I'm two years out till completion, as I am currently about 6-8 months from finishing a 32 ford project. Thanks for the input and the great build threads. If you here of an ls miata for sale please let me know. Prefer a western car as I live in Az. and it would be much easier to inspect if it was within a day or two drive.

ghmurf

Here's a little something to help you make up your mind....


1999 with 5.7 LS6 from 2001 Corvette Z06.
T56 6 Speed
Ford 8.8 TracLoc Diff
Ported Throttlebody
Mild Comp Cam
Underdrive Pulley

Dyno Tuned 410 RWHP

Goodwin Racing Stage 4 Big Brake kit w/Wilwood 6 piston calipers front, offset stock on rear...DBA 5000 rotors

Adjustable coil overs all around with Tokico 5 way adjustable gas shocks

Boss Frog Conversion Kit and 6 pt roll bar plus frame rail reinforcements

New seats, new top, fresh paint, new carpet, custom LED tail lights

pan heat shielded inside and out

and lots more...

PS: Excuse the mess...doing ground up refresh on Vemom

charchri4

Huh? Nice intro post for the introductions section but how is this helpful to this discussion? OP mentioned he was in the market are you selling your car?

rugger

^ Thread police

charchri4

Yes indeed and that is why this site stays relevant and effective for it's members. I just sifted through 66 posts on Hotrodders.com for an answer to the OP and 60 of the 66 posts were off topic, back biting or nonsense.
Anyone use UreKem Paints - Hot Rod Forum : Hotrodders Bulletin Board

It is very likely I am missing the point of his post which is why I asked ghmuf to clarify how it contributes to this topic. I'd really like to see the post in the intros with lots more information about him and his car.

ghmurf

Sorry guys. Brand new to the forum. First post ever. No disrespect intended. Chastisement acknowledged.

Only relevancy is to illustrate how nicely an LSX fills the engine bay. Originally bought a Ford 5.0 and T5. Studied overall balance and power to weight ratio and concluded aluminum block was a bit of an advantage. The choice proved out a good choice on track. With LS weight being somewhat offset by Ford cast iron diff it ended up being roughly 52/48 front to back. Not too difficult to corner balance from there.

And nope, not selling.

be good

300Hp in a miata is not allot. trust me you will get bored of it. kinda the reason i'm at 425hp and still looking for more.

Oldgrayfrog

I'm by no means an expert on these matters, but once you go to aluminum heads on the 5.0 engine, and most folks do as they are cheap and plentiful, there is little to no weight difference between a 5.0 and an LSx engine. The iron block of the Ford is also very low and so keeps the weight where you want it. Given the number of super cheap 5.0 sources right up until recent Ford Explorers V8's and the wealth of knowledge as to how to make a 5.0 make cheap horsepower, the 5.0 makes a lot of sense. Have you seen how cheaply you can get a supercharger for a 5.0? If 300 horsepower does get dull, 450 is a days work away. Yes, GM has done amazing things with it's LSx engine, but being new doesn't necessarily make it better.

charchri4

Agreed the weight thing is a non issue. With aluminum heads the weight is close enough to apples to apples to debate all day and never have a winner. I also agree that the cost to build a Ford is much less than an LS as long as you don’t try to push it past its comfort zone. Sure you can push a SBF to 425 HP but it takes a bus load of money and effort. In the LS with a cam and tune it breaks 425 hp without cracking a sweat.

But still it is an impossible comparison. Both engines are great engines but are as different as can be. Besides the LS being 14% larger displacement the 40 years’ worth of R&D absolutely makes a difference. There are a lot of really good reasons they don’t make them like they used to. But that’s not to say the newer engine is better for the Miata. No question the ford is cheaper to build, fits in the car better and sounds a million times better than the LS.

So it comes down to what you want out of the build. If a guy is on a budget and can live with 300 HP the Ford wins hands down. If a guy has an extra 5000 laying around and wants to push 425 hp then the LS wins hands down. But as I see it 300 HP in a 2400 lb car is more than enough to lose your license, rack up 5 figures in fines and legal fees and make it impossible to buy insurance.

caymantrackrat

I come to this web site everyday looking for that good deal on an already done car. Then I go to this forum to see what the people who drive them have to say about the 5.0 vs the LS. You guys don't make it easy to decide which motor to go with. The research I have done shows the ford with light weight parts to be about 100 plus pounds heavier. That and the easy 100 horsepower advantage makes me think the future is with the LS. Now if I could just find one.