Settle an argument : Miata Power

In reply to EvanB (Forum Supporter) :

Do you have a K100 cylinder head or a BMC A-series block with the BMW head on it sitting under your workbench?

I've always loved the idea of that conversion.

AnthonyGS (Forum Supporter) said:

Justjim75 said:

After reading the whole thread twice, i have come to the same conclusion as Keith and Flyin Miata: boost or LS the world

If you really want 200 rwhp from a 4 banger, the K24 swap seems to be getting good results.  I don't think a Mazda 1.6 or 1.8 is going to get there unless you spend even more than the K24 swap costs. 

I made 245whp with a Rotrex supercharger kit on a stock 1.8L that I bought for $5000. From what I'm hearing, a lot of K-swaps are running into the 5-digit range. Boost is much more affordable, and while the BP doesn't make big NA power easily, they are built like a freaking anvil and can take a ton of boost.

T.J. said:

In reply to EvanB (Forum Supporter) :

Do you have a K100 cylinder head or a BMC A-series block with the BMW head on it sitting under your workbench?

I've always loved the idea of that conversion.

I have a complete k100 engine. It seems like a really cool swap but out of my skills and needs for now.

NickD said:

AnthonyGS (Forum Supporter) said:

Justjim75 said:

After reading the whole thread twice, i have come to the same conclusion as Keith and Flyin Miata: boost or LS the world

If you really want 200 rwhp from a 4 banger, the K24 swap seems to be getting good results.  I don't think a Mazda 1.6 or 1.8 is going to get there unless you spend even more than the K24 swap costs. 

I made 245whp with a Rotrex supercharger kit on a stock 1.8L that I bought for $5000. From what I'm hearing, a lot of K-swaps are running into the 5-digit range. Boost is much more affordable, and while the BP doesn't make big NA power easily, they are built like a freaking anvil and can take a ton of boost.

Im pretty sure i can and will turbo my Miata for half that $5k

In reply to NickD :

250whp is "a lot" in BP terms (really not that much boost, like 11psi on my car), but if you turbo or rotrex a stock K24 you're looking at 400whp before you have to start worrying about longevity. So, Honda has us beat in that department as well. Granted, K24 is a 20 year newer design... 

Pete. (l33t FS) said:

The Saturn intake manifold suuuucks.  And there ain't much engine bay room to fix that.

I would agree.  There are a few different manifolds (And it seems the better manifold is on the worse head and vice versa)  The guys making more than ~160whp all seem to address that, any guys making "big" power with turbos.  I don't think room is as much of an issue as you suggest.  The fact that you need to build your own from scratch is the big hurdle.  Most people get to that point and then just go get a better car 

morello159 said:

In reply to NickD :

250whp is "a lot" in BP terms (really not that much boost, like 11psi on my car), but if you turbo or rotrex a stock K24 you're looking at 400whp before you have to start worrying about longevity. So, Honda has us beat in that department as well. Granted, K24 is a 20 year newer design... 

While that's true, it also adds another $5k (min) to the engine build.

If the goal is the least expensive way to get 200hp in a MIata (how ever you want to measure it)- I think Nick's point of boosting is the cheapest option.  Far cheaper than an engine swap.  

If 400hp is the goal, the equation changes.  A 400hp BP vs. a 400hp K24 then becomes more of an issue.

Also, for some things, displacement matters.  For instance, if you were building a DM car, a K24 would not be legal (K20 would be ).  Heck, if you were doing a LSR car, the difference between a 2.0l and anything above that is a big deal- as they are different engine classes so different records to chase.

The buddy mentioned nothing of exotic intakes or exhaust, and absolutely no power adders. No head swaps. No E85 was mentioned, either. On boost or spray, 175-200,  you can do all day long. 

His mindset is old school SBC. Intake, cams, exhaust,  and a tune. Sure...

I'm just glad you're armed with good info to retort with should he bring it up again. (He will.)

alfadriver (Forum Supporter) said:

If 400hp is the goal, the equation changes.  A 400hp BP vs. a 400hp K24 then becomes more of an issue.

I think at 400 hp you're better off with an LS3. :)

Appleseed said:

The buddy mentioned nothing of exotic intakes or exhaust, and absolutely no power adders. No hwad swaps. No E85 was mentioned, either. On boost or spray, 175-200,  you can do all day long. 

His mindset is old school SBC. Intake, cams, exhaust,  and a tune. Sure...

The one sentence summary is that on the old school chevy you have a bunch of different heads to choose from.

Some SBCs with the wrong heads will struggle to break 200hp.

alfadriver (Forum Supporter) said:

morello159 said:

In reply to NickD :

250whp is "a lot" in BP terms (really not that much boost, like 11psi on my car), but if you turbo or rotrex a stock K24 you're looking at 400whp before you have to start worrying about longevity. So, Honda has us beat in that department as well. Granted, K24 is a 20 year newer design... 

While that's true, it also adds another $5k (min) to the engine build.

If the goal is the least expensive way to get 200hp in a MIata (how ever you want to measure it)- I think Nick's point of boosting is the cheapest option.  Far cheaper than an engine swap.  

If 400hp is the goal, the equation changes.  A 400hp BP vs. a 400hp K24 then becomes more of an issue.

Also, for some things, displacement matters.  For instance, if you were building a DM car, a K24 would not be legal (K20 would be ).  Heck, if you were doing a LSR car, the difference between a 2.0l and anything above that is a big deal- as they are different engine classes so different records to chase.

Yeah, the original scenario was "To break 200hp, a K24 is cheaper." That is false. You then changed it to "To break 200hp and have more headroom left, a K24 is better" or "To break 400hp a K24 is cheaper" and that is true. Not to be too argumentative or pedantic, but you changed it from AnthonyGS original scenaro,

Cactus said:

Some SBCs with the wrong heads will struggle to break 200hp.

*cough* late 80's centerbolt TBI heads *cough*

bobzilla said:

Cactus said:

Some SBCs with the wrong heads will struggle to break 200hp.

*cough* late 80's centerbolt TBI heads *cough*

Are those the damn "swirl-port heads" where they block off half the intake port going into the bowl to generate a vortex?

codrus (Forum Supporter) said:

alfadriver (Forum Supporter) said:

If 400hp is the goal, the equation changes.  A 400hp BP vs. a 400hp K24 then becomes more of an issue.

I think at 400 hp you're better off with an LS3. :)

 

That's always where I've drawn the line for the V8 - 400+ is least expensive via LS. As a bonus, you get a full drivetrain that can handle the power and that bolts together, a shed load of torque and better parts support than a highly boosted four. 
 

For 250 rwhp and below, a boosted stock engine is the go-to. It's that awkward in between area where you're either rebuilding the BP or swapping in something else, and then putting the rest of the drivetrain in peril so you either crosss your fingers or keep swapping in more alternate pieces. 250 is actually the long term capability of most of the stock parts so it's a really good target.

But you ain't getting there on a BP without pressure :)

NickD said:

bobzilla said:

Cactus said:

Some SBCs with the wrong heads will struggle to break 200hp.

*cough* late 80's centerbolt TBI heads *cough*

Are those the damn "swirl-port heads" where they block off half the intake port going into the bowl to generate a vortex?

yep. The absolutely tiny cam didn't help either. nor the 8.5:1 compression ratio

EDIT: stock specs for a 350ci V8 was a .382/.402 lift 

In reply to NickD :

I agree but the OP was looking for NA power. The rotrex is awesome, and Track Dog is here in DFW.

In reply to Keith Tanner :

Spot on.  It's that add 300 rwhp target that causes difficult decisions.  Honestly I think once you pass this number, it's LS or lots of headaches.  A SBF swap will struggle past this power number too but fills the 250-300 rwhp niche well.  It's just exoensive too.

Anyone want a Ford 8.8 31 spline Cobra diff? I want to use the GM Camaro diff so I can buy a certain companies on the shelf awesome exhaust system.  

The problem is that everyone reads on the internet that 250 is fairly easy and repeatable, so they call and ask for 300 because, well, who wants what everyone else has? It's been going on for 15 years :) 

AnthonyGS (Forum Supporter) said:

In reply to NickD :

I agree but the OP was looking for NA power. The rotrex is awesome, and Track Dog is here in DFW.

That's not how i would put the original post- which was not agreeing with someone he knows who thinks it would be easy for a BP to make 200hp since a Honda 1.6 allegedly did it easily.  I'm pretty sure he disagrees with that premise.  This whole thread is about agreeing with that, and if you really want that power out of a BP, forced induction is required.

Keith Tanner said:

The problem is that everyone reads on the internet that 250 is fairly easy and repeatable, so they call and ask for 300 because, well, who wants what everyone else has? It's been going on for 15 years :) 

300 rwhp was a magic number at the beginning of the 21st century.  LS1s did it so easily everyone wanted that number.  I had Mustangs back then and everyone was gunning for it.  I also had a Miata and everyone was trying to boost their way there. Few in either camp made it.  The easiest way was and probably still is sell what you have and go LS.  Heck 996 and 986 P cars are pretty light but the amount of whining about 300 rwhp would make you think an LS swap is the only answer there too.  

Appleseed said:

The buddy mentioned nothing of exotic intakes or exhaust, and absolutely no power adders. No head swaps. No E85 was mentioned, either. On boost or spray, 175-200,  you can do all day long. 

His mindset is old school SBC. Intake, cams, exhaust,  and a tune. Sure...

I'm just glad you're armed with good info to retort with should he bring it up again. (He will.)

You can't do that with old school SBCs, either.  There are a lot of 250hp "500 hp" Chevys out there.

AnthonyGS (Forum Supporter) said:

Keith Tanner said:

The problem is that everyone reads on the internet that 250 is fairly easy and repeatable, so they call and ask for 300 because, well, who wants what everyone else has? It's been going on for 15 years :) 

300 rwhp was a magic number at the beginning of the 21st century.  LS1s did it so easily everyone wanted that number.  I had Mustangs back then and everyone was gunning for it.  I also had a Miata and everyone was trying to boost their way there. Few in either camp made it.  The easiest way was and probably still is sell what you have and go LS.  Heck 996 and 986 P cars are pretty light but the amount of whining about 300 rwhp would make you think an LS swap is the only answer there too.  

Correction, it's been going on for nearly 20 years. Man, I've been doing this for a while. 
I'd ask people "why 300?" and invariably they'd tell me "because everyone has 250". LS engines were never mentioned, it was always just to have a slightly bigger hootus than the other Miata owners. 
About 12 years ago the LS Miatas really came on the scene and we had a rapid escalation of power availability. 

Pete. (l33t FS) said:

Appleseed said:

The buddy mentioned nothing of exotic intakes or exhaust, and absolutely no power adders. No head swaps. No E85 was mentioned, either. On boost or spray, 175-200,  you can do all day long. 

His mindset is old school SBC. Intake, cams, exhaust,  and a tune. Sure...

I'm just glad you're armed with good info to retort with should he bring it up again. (He will.)

You can't do that with old school SBCs, either.  There are a lot of 250hp "500 hp" Chevys out there.

The nice thing about old SBC or SBF engines is you can open up a catalog and choose inexpensive (in the grand scheme of things) heads that flow way way more power than stock.  I have often wondered why you can't do this for Miatas and other 4cyl cars.

Keith Tanner said:

AnthonyGS (Forum Supporter) said:

Keith Tanner said:

The problem is that everyone reads on the internet that 250 is fairly easy and repeatable, so they call and ask for 300 because, well, who wants what everyone else has? It's been going on for 15 years :) 

300 rwhp was a magic number at the beginning of the 21st century.  LS1s did it so easily everyone wanted that number.  I had Mustangs back then and everyone was gunning for it.  I also had a Miata and everyone was trying to boost their way there. Few in either camp made it.  The easiest way was and probably still is sell what you have and go LS.  Heck 996 and 986 P cars are pretty light but the amount of whining about 300 rwhp would make you think an LS swap is the only answer there too.  

Correction, it's been going on for nearly 20 years. Man, I've been doing this for a while. 
I'd ask people "why 300?" and invariably they'd tell me "because everyone has 250". LS engines were never mentioned, it was always just to have a slightly bigger hootus than the other Miata owners. 
About 12 years ago the LS Miatas really came on the scene and we had a rapid escalation of power availability. 

I agree it really is an arbitrary number and no idea why everyone thinks it's the magic number.  I prefer a car that is fast but can be enjoyed, driven in traffic, driven at the track when time permits.  A lot of high hp setups do not do this.  They are one trick pony's.  I like a wide useable power band.  I'm willing to give up max power in order to get a broad torque curve.  But I'm an oddball, I know that.