Sunshine Guy

I'm certainly not up to date on the "new" Chevy small block stuff (ask me about double hump fuelie heads and I could help). However, that seems like a big weight difference between iron and aluminum blocks.

A bare 5.0L Ford block weighs 135 lb., so an aluminum substitute would have to be filled with helium or something to save 100 lb. I calculated the difference once, a long time ago, between using a stock iron block and a rare, aluminum racing block. I don't remember the exact weight savings, but I do remember it figured out to almost $100 per lb.

I wonder if that 100 lb. difference figure might be comparing an iron block and heads to an aluminum block with aluminum heads? That seems more feasible to this ignorant bystander.

Meierznutz

Sunshine, think about that... if you put the same heads on different blocks, they still weigh the same. I think you were thinking iron block and heads but there are no iron heads for the LS. What we need is someone with two bare blocks and a scale to get us some facts!

charchri4

Yeah I thought the 100 lbs seemed high too but really had nothing to go on to comment with. If memory serves me even close to correct when GM went to aluminum heads on the LT1s it dropped 45 lbs off the engine. I would think for the block the number would be closer to 75 lbs at most. But I have never put any of it on a scale to have any useful data.

cvx_20

Actually, the first truck motors had iron heads. Just for a couple of years.

Here's some weights I came up with:

Iron block 6.0 versus aluminum 5.7, both bare blocks with main caps.

I have an iron 4.8/5.3 block that I will try to post up later, I think it's supposed to be slightly lighter.

Mike

charchri4

Mike I just saw your blog post and was totally surprised at the SBF number! No wonder they make such fine builds! I'm going to book mark that one. THANK YOU!

MRM331

So according to Mike's findings an iron ford block weighs less than 20 pounds more than an aluminum ls block... I wonder if the driveline of a Ford build with aluminum heads and a t5 actually weighs LESS than a LS with a T56...

-Jason

charchri4

Yeah that was 10 grand well spent on the LS Jim

cvx_20

There's more to come. I have some aluminum heads that will be compared to GT40 heads, the trans obviously, and some other individual items. A significant factor, I'm sure, will be the intake. The plastic intake of an LS is much lighter than the Ford solution. Somebody needs to 3D print an intake!!!

Mike

MRM331

I'd love to see one that feeds from the front middle like the LS. I'd love to have that option when I go to individual coils someday (MS3).

-Jason

MRM331

Even if the weights come out the same (which I believe they will) the LS still has a few advantages. The biggest is out-of-the-box power. While it takes effort, knowledge and research to build a 400 hp Ford you can get a 400 hp LS by simply pulling the crate off the engine you just had sent to you. I still think the total cost of a built 400 hp Ford 5.4 liter is the same or less than a crate LS but the ease of simply ordering the LS is an advantage if you want to get going quickly. The ECU programming of an LS has a 30 year advantage on the mid 80's A9L programming of the Ford. Because of this it can get somewhat better fuel mileage than the Ford can without a lot of tuning or a whole new ECU. I do think I can get a Ford running on a MegaSquirt 3 with coil on plugs and other upgrades to get LS-comparable economy but again that takes a lot of effort and research (not money unless you have someone do it for you).

-Jason

Sunshine Guy

Yes, I was thinking iron block and iron heads. The last Chevy small block I built was in the early '70's. You mean they've changed???

Sunshine Guy

I believe a Ford with aluminum heads and a T-5 will indeed be lighter than an all-aluminum LSx and T-56.

However, once you build the Ford up into LS power territory (very doable), now you need a heavier gearbox for reliability. So I think the weight thing is not a big plus or minus for either camp.

The big advantage of the LS, as Jason said, is power out of the box and newer technology. The big advantage of the Ford is it is physically smaller and fits better in tight engine bays.

You can have an awful lot of fun with either one.

charchri4

And this good sirs is what I love about this place. Leave it to Sunshine to take a decades long heated debate and perfectly crunch it down to the only relevant point!

charchri4

You know this is what's so difficult about trying to figure out which is better. For every advantage each of them has there is an equal disadvantage. You are absolutely right on everything you said here Jason but an equally compelling list can be written for the 5.0 as well.

Beyond that there is the comparison of the kits and swap itself to have this same debate all over again with.

My personal opinion is the 5.0 is not going away anytime soon because there is no overwhelming advantage to any of the alternatives for it. That being said I also feel over the next half dozen years the LSX is going to be the game changer that could truly give old blue a run for it's money...

MRM331

I really think it comes down to where you want to spend your time and money and where you feel your particular skill set lies: Engine building or Chassis modification. I think that if one were to build two identical 400 crank hp Miatas, one with a LSx driveline and one with a stroked Ford, both using the avaible kits (not home built) the differences would come down to the details of the builds, not the performance of the finished products.

The Ford build would:
-Likely cost less (although professional engine building could bring it close)
-Require knowledge of ECU programming/tuning and engine building to get LSx economy and power out of the Ford UNLESS you are happy with its stock power (225 crank hp)
-Take less time to build the actual car, not counting the actual engine build

The LSx build would:
-Likely cost more (all kit components are more expensive, donor parts are more expensive, ecu requires professional reprogramming for OBD2 compliance)
-Require more welding and general automotive skills to modify the chassis and work out the fuel and other systems but would not require the engine building and tuning skills of the Ford

In other words, if you want a 400 hp, kit built V8 Miata you have the following choices:

Ford: More of funds and effort go toward engine building, less toward the chassis/kit
LSx: More funds and effort go toward chassis/kit, less toward engine building (it comes ready to bolt in)

Just my thoughts.

Jim I agree with your last statement UNLESS someone figures out a way to mount a Ford coyote engine in a NC or ND in a timely manner (Are you listening Martin?????).

You know I love debating this with you Jim

V8droptop

The coyote is still an underdog in the LSx dominated field, IMO. But I'm glad the conversation carried on after my small mention of weights. Here is a nice summary of weights:
Weights of LS Blocks - LS1TECH

Most of the LSX vs 5.0 debate isn't really Miata centric. Honestly, the miata chassis seems to become overwhelemd with power before EITHER engine really runs out of steam. But lets look at some more engine facts:

Ford's 302 5.0 platform
Max bore: 4.060" (pushing it)
Max stroke: 3.4"
Aftermarket blocks can make 363 w/ more bore
Approximate HP rating of stock block: 500-600hp (blocks like to split)
This engine has its design roots back to the 60s, and modern EFI and blowers weren't exactly built into its DNA.
Ford V8 Stroker Engine Sizing : Five.Oh Info

LSx Blocks
Factory Bore range: 3.78 to 4.125 (stock engine options)
Aftermarket Sleeves, stock block max bore: 4.185, 4.2"
Factory Stroke Range: 3.267-4.00"
Aftermarket Max stroke: 4.2", 4.5", 4.6"
Stock Block hp levels(alu)" 900-1000hp
Stock Block hp levels(iron): 1400hp-1700hp+
This motor was conceptualized to cover Gm's V8 needs across the board, from a 4.8L iron V8 in a 2wd truck for towing, to the Top of the line Z06 corvette 7.0, and the highly successful C5.R racer. A modern design, with Modern computer design and testing, as well as 50+ years of engine experience over the 5.0, its a truly modern engine design.
The increased bore size options as well as increased HP capacity shows where the extra 80lbs in the iron Chevy vs iron Ford comes from. Anyone recall GM claiming the Aluminum LSx is 30ish% stronger than the outgoing iron SBC? I can't find the exact number, but recall from advertising. The main cap design helps in power holding.

LS1, LS6,LS2, LS3, L99, LS4, LS7, LS9 And LSA Engine History - GM High-Tech Performance
LS MAX POWER??? - Yellow Bullet Forums
http://www.callies.com/crankshafts/u...tra-billet-ls/
ERL SuperDeck II: 500 Cubic Inch

I'll give you that I'm biased towards my choice of the LSx platform. But my reason for going this route is based on fact as well as preference. IMO, if you bring a 5.0 to the point you need a stroker crank, aftermarket block, or aftermarket injection system, you're better off going to the LSX platform. Because you can get your stroker crank from the factory parts bin, you already have strong block options, and the injection system, especially the 58x tooth setup and e67 ECM, are already modern and very capable. Even Gaskets, Oil pumps, and cams are great right from GM, from the 5 layer MLS to 7 layer MLS gaskets and High performance GM oil pump (ls2) And hot cam.

Anyone have more to add? This is just brief, and if anyone has a correction to my memory, please let us know! I don't always recall specs well, but the block weight seemed to be right! The LS engine is in another league vs the 5.0, its far more modern, and supports over 7.6l of possible displacement. The real question is, is it necessary/usable in a Miata? In some cases, probably not.

I wanted to add:


This is just one feature in the LS series you can see is an advantage to the Ford design. The stronger integrated mains

charchri4

Wow that is really good stuff there ^^ Nick and much it I was not aware of or didn't crunch down like that. Thanks for such a detailed thoughtful post! I feel a sticky in the making here...

The problem with the debate is I so rarely disagree with you Jason! In this case I think you are spot on but your number is a tad off at 400 HP. With what it takes to push a NA 5.0 to 400 hp I would think the break even number would be closer to 350hp between the 2.

As for the Coyote I think all the stars will align on that one in time. About the time empty nest hits for you there will be plenty of Coyotes and NDs for you to show us how it's done!

Meierznutz

Ford Guys will always want a Ford, Chevy Guys will always want a Chevy....and us old Pontiac FARTS will have to find something else!

Look, I had 425 HP of dyno'd 5.0 ready to go into my Miata. My nephew talked me into the LS and I am happy he did. I wasn't thrilled with spacing the subframe to clear the carb or cutting the hood supports. The LS fit and the ECU was an easy re-pop. That is why I went to it. I absolutely agree that 400 hp in either engine is a lot for a Miata to handle.... that is why I am cutting weight and trying to double the hp of the last car!

Now if there were a way to get that Hemi in there....

V8droptop

I agree with you on that one. And there's no doubt you have a lot of guys with backgrounds in each come to the miata for the platform, not the engine it came with, thus all these V8 swaps.

I also see with chevy's, you have the older crowd who can't get away from the gen 1 SBC, kind of like the 5.0 vs mod motor and coyote, now 3 generations old. Although, with the miata the mod/coyote can't be used for obvious reasons (120 degree bank, for one). Around here in the ***-backwards hinterland, when I talk about the gen 3/4LSx motors most people's eyes glaze over and you get, oh, so its a small block Chevy? Or something of the likes.
Oh well!

I am still firmly in the LSx camp, so I'll admit some bias, but along the same lines as earlier, Ford is now 2 generations ahead of the 5.0, and their newest motors make the power stock that has been known to split the 302 block, and these are the motors competing with the LSx and now LTx series. The old 5.0 and LSx barely lived together at the same time, and even then the 5.0 wasn't in any high performance cars, the mod motor took over all performance applications, it was only in Trucks/Suvs for a short time with the LS1 and truck 4.8/5.3/6.0s.

MRM331

I agree that in any other application where the chassis and available tire widths can handle greater than 400 hp the lsx is the way to go. Building a old 5.0 to that spec when you can just uncrate a new lsx with the power you are struggling to make the ford put out would be futile. The point is that unless you want to seriously reinvent the car's chassis 400 hp is about as much as you are going to be able to use in a Miata. Because of that limiting factor I think in this application the old 5.0 stuff is very relevant still.

-Jason

Sunshine Guy

I'm sure it does.

I have a set of GT-40X type aluminum heads from Flo Tek sitting in my office. At 22 lb. each fully assembled, they weigh a whopping 50 lb. less than a pair of stock, Ford 5.0L iron heads.

Based on Tremec's current, published literature the T-5 behind the Ford motor weighs 75 lb; the T-56 behind the Chevy weighs 135 lb. Bellhousings and clutches are probably close to a wash, so figure 60 lb. saved here for the Ford camp.

I don't have the actual figures, but there is not going to be a big difference in rear end weights.

So, running the numbers, if the stock Ford 5.0L was indeed 20 lb. heavier than an all-aluminum LSx, considering comparative, overall weight of engine, transmission and rear end, the aluminum head Ford might be around 90 lb. lighter overall. I have no data to confirm or deny that 20+ engine weight difference, so I'm really just comparing drivetrains.

Of course, it's good that the overall Ford set-up is lighter because, considering stock or mildly/cheaply modified engines, the LS is going to make substantially more power. Lean really heavily on the Ford motor and you will likely be thinking about upgrading to heavier drivetrain parts.

It really isn't too hard or expensive to get the intrinsically asthmatic Ford up to the 400 HP level at the crank. Heads, cam, intake, throttle body, mass air meter and some longer arms on that stubby crankshaft will do the trick. The T-5 has lived remarkably well behind this level of power when avoiding slicks and really abusive clutch behavior.

A very well developed, mature aftermarket with lots of competition has brought component prices down to attractive levels. Especially if you start with a tired motor that needs freshening anyway, a stroker kit with new crank, rods, pistons, rings and bearings of acceptable (400 HP) quality represents a good value for around around $1200.

The stock block will handle this power level fine if it is sound to begin with and machining/assembly are good. A main stud girdle isn't too expensive and helps to reduce the lower end strength deficit compared to the Chevy. This route might come in a few bucks more than a used LS engine around the same power level, but now you are starting with a virtually new motor. Refresh the LS motor, and you're probably somewhere in the same cost ballpark again.

It always comes back to the same things. The entire Ford drivetrain is smaller, weight competitive, and physically fits into the Miata better. The Chevy has stronger, more modern technology and will provide more power with less hot rodding effort.

Pick one. Throw a dart if you have to. You'll like it.

V8droptop

Yea, agree, it is still relevant for the Miata as far as a price/power/fit comparison. The LSx woulds till win out in efficiency, I would imagine, though I have no testing/proof on that, must admit I'd be surprised if it weren't the case though, especially if you used an AFM&E85 5.3/6.2 for instance.

On the tire size issue, 275s are availible, still probably not enough tire, and then there are race tires in the range of 10.5/23.0-15 to 11.5/23.5-15, avon makes a few GT3 class tires in this size, If one wanted to have a lot of fun on their track weekend, I'm thinking this would be a viable option, and maybe about as good as it gets for grip with factory sheet metal and flares.

523-LSX-NB

Understanding the conversation regarding the 5.0 vs the LSX block...(because they are the most popular V8 options for the Miata). However, IMO, it's not a fair comparison as they are a generation apart in design.

For me, it's as simple as:

-Ford 5.0 provides decent power/tq @ low cost including the cost of the required Miata associated build parts.

-LSX provides a higher power option @ a higher cost to engine & related Miata swap parts.

-Weight is weight. Either want to reduce it as much as possible or can live w/more.

I remember when "the internet" claimed that the Miata couldn't support over 350 RWHP. Now there are swaps making over 600 RWHP. Am not sure where the limit is. It all depends on what the builder is willing to modify & spend.

Finally, the real limit of a small block is the piston rod (before the block or mains on an LSX). High combustion chamber pressure means high deflection of the rod bearing arch. This greater deflection can deflect the rod bearing into the crank shaft which eventually results in a spun rod bearing. Stronger rods do help by doing a better job of resisting deflection, but w/ bearing clearance @ only .002"-.003", it doesn't take much. Bottom line is that you are more likely to spin a rod bearing before damaging the block.

Gator Bait

Yup...I had zero interest in an oem pwrd Miata. Zip, none, zilch.

Blasphemy!!!

charchri4

I'm with Gator on this ^ one Jason. My car pulls disturbingly hard at high speeds and doesn't take long to go from 100 to 140. That's when you can use it all and it's the ponies over the 400 mark that so quickly bury the speedo.