Piston, Crank, Rods, and flywheel upgrades. Need help!!!

[Gunny1162]

I am currently upgrading my '92 1.6 SOHC B6-ME w/ Mtx by swapping to the B6-DE head, intake, exhaust header, harness and ecu. I could use some advice on what crank, pistons, rods, and flywheel to use for more strength. I want to stick with the F series mtx that I already have. Are there any heavy duty half shafts that are compatable with with that mtx that still match with a '90 323 hubs that I discovered are on my mx when I replaced my lower ball joints recently. Any help and advice would be a great help. I would do the BP swap but I'm resricted due to cash restrictions. Thanks again.

Gunny1162

[projectzemx3]

lol a bp swap would be way less then diving into replacing pistons rods and going so far as a crank

[MazdaNut]

You'll need the pistons and rods from the DOHC motor.
I'm not sure if the valve reliefs will line up right on the SOHC pistons.
Miata pistons will get you 9.4:1 CR instead of 9.0:1.

I doubt your halfshafts are the weakest point as long as they're in good shape.
The F series diff will probably go before you break a CV joint or axle.

Unless you're getting these parts for next to nothing, projectzemx3 is right.

[Ryan]

I was under the impression the B6D head didn't fit on the B6M head?

I thought the coolant/oil passages didn't line up...

[Gunny1162]

As far as the compatibility goes, B6-de head will fit and work since the blocking of the different passages is controlled by the head gasket. Both blocks use the same casting and machining.

So if I do get my hands on a BP then my next question would be what is the compatibility of my f series Mtx and motor mounts? I do have a BP4W head that I've been messing with for a few days off a '99 miata, if i can get the pcm, harness, intake, header, and block; will it fit in the engine bay and mate with my tranny?

I know my B6-ME block has been bored .010" over with different pistons from when I replaced the head gasket three months ago and its sporting approx 9.8:1 CR. I believe the cam has been replaced as well but I'm not sure. All I know for sure is that I'm pushing close to 140 fwhp @ 4500. The previous owner did something and atleast took care of it. Lucky me.

[MazdaNut]

Wow. I'd certainly like to know what has been done to that motor. Dibs on the head if you're selling it. What are you using for a header? 9.8 is about what I figured with Miata pistons and maximum milling on the head and block. I was just hoping for a 3-digit horsepower number.

[Ryan]

As far as the compatibility goes, B6-de head will fit and work since the blocking of the different passages is controlled by the head gasket. Both blocks use the same casting and machining.

So if I do get my hands on a BP then my next question would be what is the compatibility of my f series Mtx and motor mounts? I do have a BP4W head that I've been messing with for a few days off a '99 miata, if i can get the pcm, harness, intake, header, and block; will it fit in the engine bay and mate with my tranny?

I know my B6-ME block has been bored .010" over with different pistons from when I replaced the head gasket three months ago and its sporting approx 9.8:1 CR. I believe the cam has been replaced as well but I'm not sure. All I know for sure is that I'm pushing close to 140 fwhp @ 4500. The previous owner did something and atleast took care of it. Lucky me.

I don't know for sure about the head thing, as I never bothered with the 10hp gain when the BP was so attainable(40+)

The BP is a DBI. We recommend using the G series that comes bolted to it, because that trans can handle much more power, and has more desirable gearing. The F trans was a for the low power B engines. Everything external swaps. mounts, etc, all the exact same.

I don't think the Miata motor fits/bolts in, and the electronics will be complicated. Sure you can have the engine harness/pcm, but setting up the tacho and other controls from the cabin will be fresh ground not covered by anyone here.

140 WHP seems optimistic on the 88 hp motor even with the .01 over and a cam.... is that the 'gut dyno', butt dyno, mustang dyno, or a real dyno?

Check your compression and back calculate to figure the ratio.

2.5L V6 KLDE hardly puts down 140 WHP....

So, I'm calling BS on that. dyno sheet please.

[RS_OBD'oh_2]

I also have to call BS on the 140fwhp. Does not seem even close to realistic.

There is not much else I could comment on... IF you have that power, it's already better than a BP and there would be nothing else you could really do to get anything else out of it. You should have already needed a clutch upgrade if you are putting 160-ish hp to the fly. Crank, rods, pistons, etc... I agree that it would be cheaper to get a BP than do the machine work needed for these items.

Ya, Calling BS again. Sorry. I wish you have that kind of power to the wheels... I do, but it's just not realistic to double the power output of your engine without lots of air or lost of coin.

[Gunny1162]

As far as the dyno goes, it is a chassis dyno at my buddy's college for his auto program. As for the accuracy of the dyno, that's a bit questionable considering it's older and only good for up to 250 hp. This is merely what was reported to me by my buddy. I'll see if I can get it on a newer chassis dyno to verify the numbers my buddy told me.

So as far as the bp swap, what would be the best donor car and how hard would it be to swap in an OBDii BP?

[Ryan]

the swap is direct bolt in...

As far as OBDI vs OBDII, its always easier to stick with whatever your chassis currently is, but its possible to switch, but you need a lot more wiring. I'm not sure if you need the dash harness or not, but I'm sure it can be searched for on here.

The entire thing is direct bolt in no matter where you get the motor. Mercury tracer LTS, Ford Escort GT, Mazda Protege (GT or LX, depending where you live, but beware some are 1.8L SOHC)

There are some tiny differences that you should look out for, like the for fuel supply system is slightly different, and ATX vs MTX throttle bodies are different, and of course, ford vs Mazda valve covers.

Check the worklogs, check the 4 cyl FAQ....

[Gunny1162]

Thanks for the heads up on what to watch for. Any advice on where to get some high performance pistons, rod, crank, and flywheel for the BP then? Is there a manufacturer that should be avoided or one that is more desireable than the other? Thanks again for all the help so far Ryan.

[Ryan]

BP crank is said to be made of invincible, don't sweat that.


rods and pistons... basically you get what you pay for. Check the worklogs for good ideas.

[RS_OBD'oh_2]

Agree with Ryan for the worklogs.

First, what are you building this car for? What are your HP goals? You don't put low compression pistons in a car that won't be boosted. This is about planning. We can't tell you anything if you don't give us your plans.

Note: The BP is not like the B6... you can get parts any/everywhere. Google can help out a lot here. Simple questions can be solved with a search. You may piss people off if you ask a question that has 50+ topics on it already.

Do some searching, find out what can be done with your car.. find out if you have the $ and can afford the down time. Then research the parts needed to get your desired results.