miata motor?

i keep pondering this more and more everyday. the only thing holdin me back really is my 2.2 is a fresh rebuilt and has no problems what so ever and is very very reliable and im goin to be drivin the truck daily.



-justin

the trouble is, if you stroke the bp to 2.0, you end up with a setup that cant spin as high as the same 2.0 fe3 and has smaller ports and valves to support that capacity. ie, you end up with less power/torque at the same psi at the same revs all else being equal, and significantly less power for the same boost overall because you cant rev it as high safely if all the other components are equally well built.

a stock fe3 will spin 7500 no problem. a stroked bp on stock built rods just wont, and will wear out bearings faster too if you tried. if you add built rods into the equation, put them in the fe3 and spin it to 8k.surely a set of cams could be made and rods bought for the money a custom stroked crank and rods would cost?

at home all motors are little bitty turbo motors, the v8s just dont feature :-)

the main points here are these :

fe3t > bpt for both power and reliability
fe3t is an easier swap than bpt because it drops right in.

the bp is a great motor, but its on the small side for a heavy truck, and overall it cant make the torque or power that the easier swap can make.

bp is good in a light miata or 323 hatch, but when you have to butcher mounts to make it fit in a ute when there is a superior option that drops right in and is as cheap or cheaper, why would you do that?

fyi, the kia comes boost ready at 9:1 comp ratio. just add manifolds and turbo :-)

my fe3t is good for a bout a 13.0 at the moment on 17psi. once i up that to 27psi it should pull a mid 12 in heavy load carrying capable trim.

i'm not knocking the bp, i just believe its a harder swap than the kia and less good overall for this application.

theres nothing to swap you rebuilding a kia motor in your garage and sorting out wiring etc and then dropping it in one weekend.

you'd best have some spare transport for that week incase you didnt finish, but...

First off let me say I have no interest in an internet pissing match, I just love a friendly debate.

I agree with you completely fe3t courier, a bigger heavier vehicle like a truck needs a bigger motor. I was simply entertaining dropped90's question about the miata motor. To tell you the truth the fastest 323 i know of has a fst motor weighing in at about 750hp (thats about 7.9sec in the quarter). I just think for people with lower hp goals of 300-400 max (like myself) the bp is fine.

For this application in North America where there are few fe3's and lots of bp's with a decent aftermarket of domestic parts (ie not sending away to japan/europe) like exhaust flanges and turbo headers already made. For a turbo application where more than 250 ft/lbs of torque wouldn't likely be required, why not spend the little more time with mounting to make the rest of the job cake? Besides the smaller bp would likely yield better gas mileage (i get 35mpg in my bpt 323).

This is a non-issue as I wouldn't stroke a bp simply for cost reasons but wouldn't smaller ports on the intake side be beneficial to low end torque? and ultimately reduce lag time while increasing average power (and driveability) at the expense of that bit of top end you lose (which can be compensated for with higher boost levels)? Corky Bell describes this well in his book.

Ultimately it comes down to what you want as an end result, a super tuned 400-500hp race truck or a zippy dd (either engine could get you to either result).

I'd be interested to see what a bpt would do in a b2200 on the quarter (as my 323 does 12's consistently).

First off let me say I have no interest in an internet pissing match, I just love a friendly debate.

I agree with you completely fe3t courier, a bigger heavier vehicle like a truck needs a bigger motor. I was simply entertaining dropped90's question about the miata motor. To tell you the truth the fastest 323 i know of has a fst motor weighing in at about 750hp (thats about 7.9sec in the quarter). I just think for people with lower hp goals of 300-400 max (like myself) the bp is fine.

For this application in North America where there are few fe3's and lots of bp's with a decent aftermarket of domestic parts (ie not sending away to japan/europe) like exhaust flanges and turbo headers already made. For a turbo application where more than 250 ft/lbs of torque wouldn't likely be required, why not spend the little more time with mounting to make the rest of the job cake? Besides the smaller bp would likely yield better gas mileage (i get 35mpg in my bpt 323).

This is a non-issue as I wouldn't stroke a bp simply for cost reasons but wouldn't smaller ports on the intake side be beneficial to low end torque? and ultimately reduce lag time while increasing average power (and driveability) at the expense of that bit of top end you lose (which can be compensated for with higher boost levels)? Corky Bell describes this well in his book.

Ultimately it comes down to what you want as an end result, a super tuned 400-500hp race truck or a zippy dd (either engine could get you to either result).

I'd be interested to see what a bpt would do in a b2200 on the quarter (as my 323 does 12's consistently).

i also am just keen to air the tech stuff if i end up wrong, all the better, i learn something along the way.

i'd say 300 - 350 reliably and with minimal investment for the bp and 400 - 450 same deal with the fe3 above those figures you are looking at shit not lasting if you beat on it (and i expect to beat on all my cars like i'm trying to break them)

kias arent that hard to find though are they? yes, bps are more common, and bolt on bits are cheap, but buying a "harbour freight" mig and slapping a log mani together on a $50 laser cut flange isnt exactly the most tricky thing to do. easier than engine mount swaps IMO.

lets be honest here, those who want lots of power usually dont (or at least shouldnt) give too much of a shit about gas milage.

i never do better than about 5km/l in my cars regardless of power or weight. roughly 12mpg? something like that.

you might get 10% better gas mileage from a bp all else equal, but that would be max. most of gas mileage comes down to vehicle mass. heavy = bad

i'm not a fan of corky. right place right time, average guy. a lot of stuff in his book is crap. outright wrong. unimpressed.

the whole port size/runner length/resonance thing wont make more than about 20% difference to torque at the absolute worst. i have very short runners and no complaints about torque. making up for shitty ports with extra boost means more exhaust back pressure and more heat. it also means less power per fuel at the end of the day and more stress on the engine for the same power. thats why bad cams should be ditched asap. pushing 30psi to achieve what 20 would with better induction is somewhat pointless and counter productive IMO.

as for strip times. mine should do about 13.0 in the 1/4 i should have around 400 hp at the crank. bit less by my calcs. my ute wouldnt way much/any more than any other long wheel base one. 323's are a LOT lighter than b2000's. once i up the boost to 27psi i estimate mid 12's a bp should get you a low 13 easily enough i guess. like you say, not a lot in it except reliability and a hair or two of outright power

btw, my tune is rough as guts, its only tuned for full load, spool up tune is all wrong, its rich as shit everywhere, and only idle is close to right. i have a lot of work to do. wot full boost though, pretty sweet! you dont have to have a nice tune to make big power. power is the easiest thing for an ecu to do. finess is the hardest.

catch you later

hmm i see great points to both sides of this debate and i enjoy being able to read both of yaulls comments without you two arguing about it and debating it in a friendly manner. dont see that much anymore. its something for me to think about. my 2.2 has absolutely no problems at all and fires up every single time i want it too. both swaps sound like a good idea. i dont want a race truck by no means. i want to keep it a daily but im startin to feel the need for some speed again. and the truck is already off the road because its gettin bags after the first of the year if everything goes as planned. i have a daily right now so i have alternate transportation. i want to hear more from both sides about this topic. thanks again



-justin

If your going to the trouble of bagging it doing motor work isn't that much worse. You sound like 200-250hp would cover your needs, not a racer but will pull on any stock truck and most cars, am I right?

I'd suggest that if you aren't comfortable with programing your own engine management get a bp with a flyin miata kit and be happy with approx 3X the power of the f2.

If you are cool with all the extra involved with not buying a pre-packaged kit then definately go for the fe3 as it's a bolt in mount and trans wise.

I never touched on the trans topic before but, the centre of the bseries and miata and rx7 trans are the same except for gear ratios. This means you can choose your ratios (I'd recommend rx7 stuff for anything turbo) but you use the bellhousing that corresponds to the engine your using and the tail section that matches your vehicle. The rx7 trans works in a miata but I've never tried it in a bseries, though it looks about right. Your stock trans will work with the fe3 but I'd question the strength with 300+hp.

Just for interest's sake there is a kia version of the bp too, it's in the 1.8L sephias as well there is a destroked 1.6L version in some rio's. Apparently kia buys lots of mazda's, and other automakers, old plans for use in new vehicles.

any of the type 2 trans are only good for 200 - 300hp reliably. they arent that strong. the turbo rx7 got the type 3/R type mazda ribcase box (what i have) and is good for 300 - 500hp reliably. they are much stronger.

the stock box will handle it ok unless you are really rough on it (i am, hence the upgrade)

be careful of input shaft length with the rotor stuff. at least in some cases they are a bunch shorter.

as much as there are only two types of mazda rwd boxs the subtle differences are plentiful and will cause headaches if you arent very careful.

the miata 6 speed box is made by aisin and is the same one found in the turbo s15 silvia. they are good to 300 - 400 hp reliably.

if you go BPT and use the mx5 box with the ute tail shaft housing (easiest option imo trans wise) there is another option aside from flyin miata.

you can get a plugnplay ms unit for the miata that will just plug into the existing loom and just work. if you got the whole loom you could use that. ANY ecu you pick up will require tuning after its installed regardless of what is claimed. if you want more than oem power you need to be comfortable with learning to tune and wire, or paying someone to do it, or putting up with a poor map.

in terms of straight swaps wiring wise, you can go kia and use kia electronics or bp and use bp electronics. both are wasted spark setups.

any swap like this can get quite involved IF you want to do it properly. there are lots of corners you can cut to get it done quicker.

both the bp and fe3 are streets ahead of any sohc mazda motor. just swapping from fe 8 valve to fe3 16v nearly doubles your hp straight off depending on which fe3 you have (mine is 148ps without the turbo, stock 8v engine is 82ps) by adding a turbo i have about 5 times stock power, its insane. bp will be plenty fast. its a very personal choice at the end of the day.

one thing to consider is that the kia is decompressed stock. just add 12psi from a subby or dsm turbo and you have 250 - 300hp and it will be reliable with a good tune and not eat your stock weak box. you'll need some sort of clutch upgrade for either type of engine if its turboed. if you dont need it to be super fast, a stock fe3 is pretty decent anyway. esp with some breathing mods. when i first took mine out, i had the wastegate open, and no boost from idle to 5k, and then tapering up to 3.5psi by 7k. i had about 190hp like that, and a perfectly smooth flat controllable torque curve, i could slide it in the wet upto 120kph. should have seen the grin on my face :-)

fred.

damn im just torn still. i guess there are more people that has done the kia giving more information on the things needed for the swap and the help on the things im confused about. im looking for a quick ass daily, but very reliable at the same time. and i would like to get some descent mileage out of it as well.



-justin