Say you wanted to build a budget BP

I'd skip a generation and go Duratec/MZR with the trans out of a current Miata. Cheap, lots of options available, all-aluminum and huge tuning potential. If you can get a Miata 2.0, I think they're higher compression, less tractor-like and generally sportier than the 2.3 variants. You can also mix and match bits to get a high compression 2.3, although all the extra displacement comes from stroke.

Still 175 crank hp out of a BP isn't too far out of line. I've got a 1.6 that made 118 rwhp with nothing more than mild headwork including a 0.030" shave, an aftermarket ECU, a good header and a homebrew intake. Scale that up to the 1.8 and get the pistons out of a 2001-05 and you're in good shape.

John Brown wrote: My apologies I should have stated that my "goal" is ~175 CRANK horsepower (125-130 rwhp) on regular unleaded. It will be used as a sporty RWD commuter that gets similar MPGs as my GLI (27mpg at 80mph, 31mpg at 65)

175 crank horsepower would probably be well over 130 at the wheels; Miatas don't have that much drivetrain loss. We've seen Improved Touring 1.6's put those sorts of numbers to the wheels. The motor was built to the limit of the rules - minor port work, not street legal exhaust, probably a more sophisticated oiling system and slight overbore, etc, but nothing too crazy as the class rules don't allow it.

pres589 wrote: 3k cruise RPM with an F2T would be a bit buzzy, FE3 probably similar. Don't know about BP, I think it would be better but I lack exposure. Need to drop another ~700rpm to have a nice cruise with an F2/F2T.

My BP runs 4000 rpm all the way to work. 3000 rpm would be a massive improvement.

Keith wrote: I'd skip a generation and go Duratec/MZR with the trans out of a current Miata. Cheap, lots of options available, all-aluminum and huge tuning potential. If you can get a Miata 2.0, I think they're higher compression, less tractor-like and generally sportier than the 2.3 variants. You can also mix and match bits to get a high compression 2.3, although all the extra displacement comes from stroke.

IF it will fit, hard to argue with that. Especially since you can get the engines out of a Ranger.

But just know that if a BP fits as a bolt in, a Duratec probably wont. It may- yes, but since the intake and exhaust are on opposite sides- fluid flow in general is a major issue to deal with. (all fluids- air, water, and exhaust)

I'm a huge fan of this newer engine. But I'm also very biased.

Consider a conservative drivetrain loss for a Miata to be around 25 hp.

From what I understand from John's posts, none of these engines are bolt-ins into this particular car. The reason a BP was specified was because of the availability of an NA/NB Miata trans. But if you're willing to give that up, you can do better in a similarly sized package for probably less money overall.

Even better for the Duratec- being that they are so common to each other...

I wish I could recall how this went- but if you swap the pistons, and JUST the pistons from a 2.0 to a 2.3 or vise versa (I just can't recall)- the compression drop is just about perfect for boosting. I had a sweet turbo Mondeo wagon for a couple of years. But can't recall all of the details- besides it being an easy build.

Can we derail back to the original premise, or should I start a new thread?

I've got a spare 1.8 NA head with Web Cam 505 grind cams in it. Would this flow better than a stock 99 head for my NA build? Anyone had success pairing the VVT heads and MegaSquirt?

How much power difference are we talking between the aftermarket 11:1 pistons and the 10:1 stock 01+ bottom end?

I'm half-thinking about just buying an 01+ short block and slapping the spare head on it, but I'm also tempted by the 85.5mm 11:1 pistons that give me about 2L. Thoughts?

alfadriver wrote:

Keith wrote: I'd skip a generation and go Duratec/MZR with the trans out of a current Miata. Cheap, lots of options available, all-aluminum and huge tuning potential. If you can get a Miata 2.0, I think they're higher compression, less tractor-like and generally sportier than the 2.3 variants. You can also mix and match bits to get a high compression 2.3, although all the extra displacement comes from stroke.

IF it will fit, hard to argue with that. Especially since you can get the engines out of a Ranger. But just know that if a BP fits as a bolt in, a Duratec probably wont. It may- yes, but since the intake and exhaust are on opposite sides- fluid flow in general is a major issue to deal with. (all fluids- air, water, and exhaust) I'm a huge fan of this newer engine. But I'm also very biased.

In all honesty the intake and exhaust are on the WRONG side of the BP but there is room.

The BP was selected because I know of the transmission, have sources for very low priced EGT engines, know of a message board where those weird Mazda types hang out and have a Mazda dealership one building over that has some pretty resourceful cats working in it.

Hell, if it were a matter of ANY engine, I currently own a low mileage PTCruiser 2.4L... A set of Liberty manifolds and a 2WD Dakota 2.5l transmission would make a driver... I need to re-examine my resources.

peter wrote: Can we derail back to the original premise, or should I start a new thread? I've got a spare 1.8 NA head with Web Cam 505 grind cams in it. Would this flow better than a stock 99 head for my NA build? Anyone had success pairing the VVT heads and MegaSquirt? How much power difference are we talking between the aftermarket 11:1 pistons and the 10:1 stock 01+ bottom end? I'm half-thinking about just buying an 01+ short block and slapping the spare head on it, but I'm also tempted by the 85.5mm 11:1 pistons that give me about 2L. Thoughts?

The more compression you have, the more power you make. Mazda went from 8.8L:1 to 9.0:1 in 1996 and claimed an extra 5 crank hp. It's hard to say how much of that was due to the OBD-II computer that year and how much was the compression, but you want more Displacement also adds power and torque. So you're going to to come out ahead with higher compression, larger bore pistons. How much? Sorry, can't quantify that one for you.

As for which head will work better, I know that Integral was always frustrated with getting power out of the hydraulic lifter 1.8 (1994-97). Their solid lifter cams worked better. Can't say why, but if you go with the 1999 head then you're in good shape for future modifications.

I can't comment on MS and VVT. I think it's been recently worked out, but it's not integrated into the rest of the ECU.