DOHC B6 Information

[Advancedynamix]

iirc the 16g setups usually net around 200hp on the miatas with an FMU and injectors, but I haven't looked at that stuff in awhile. A gt2560r will get you past that 220 mark. I don't know about the 20g on a b6d, but I'm sure it's been done before.

[bhazard]

I think euro runs a super 60, or maybe just a "regular" 60.

[bhearts]

The oversize valves are being tested shortly. I do believe they are worth the effort. These engines have very small valves. Larger bore will also help with flow because the valve area of the chamber can be relieved more.
They will support 220 stock though. It's been done hundreds of times for over a decade. Visit turbomiata.com for lots of builds. Disregard all the "just go BP" banter. The same guys who push that also think Mazda makes bad oil pumps that explode from engine TQ. As if that makes any sense at all.

"This or big F/I power pulses are what explodes oil pumps" torque kills oil pumps?

[Advancedynamix]

Harmonics crack hardened steel parts, like gears and oil pump internals. Increasing the torque levels will often amplify these harmonics, but most of these shattered oil pumps have been on engines with lightweight under drive accessory pulleys and lightened flywheels. Lightened flywheels and lack of any harmonic balancer or dampener will lead to problems down he road. Also, a lot of these cars have stiffer engine and tranny mounts, which further amplifies these issues. That is all besides the point, but since we are talking B series engines, it is important to discuss the facts about where fatigue originates. TQ loads alone are rarely the cause of many of the drivetrain failures that plague these cars. Harmonic shock is what causes stress fractures to develop in hardened steel parts. Once the stress fractures spread deep enough into the part, it will fail. Hardened steel parts are more brittle than non hardened parts, so they are more susceptible to the harmonic shock loads. Also, Hardened steel parts often amplify certain frequencies, rather than dampen them. This is a reason why materials like 4140 are not ideal for flywheels, because hardened 4140 does a poor job at absorbing harmonics.

[Advancedynamix]

Okay, so I have been informed (thanks goes to Rocketman) that the MX3 b6D is a totally different animal. I have only ever seen 1 close up and it was years ago and I barely remember it. The MX3 b6D uses a different head all together. It seems to use the same head as seen on the DOHC B5 engines. That also clears up the B5 confusion. I have not actually had my hands on any of these parts, and would like for someone who has to chime in or at least PM me with some specifics. Meanwhile, I'm looking of one of these engines to play with.

EDIT: After doing some research, it looks like the block is also different. The MX3 B6D uses a block that looks like the z series block. It has more ribs and no crank vent. This seems to have been a transition engine from the B to the Z series.

[jhntu]

Ever been fortunate to investigated a B3 DOHC or no need?

[Advancedynamix]

Ever been fortunate to investigated a B3 DOHC or no need?

I've never seen one in person, but by the pictures and specs it looks like a b6d (Capri/Laser) with either a shorter stroke or smaller bore. I can't remember which is different. A destroked b6d would be fun in these cars, but probably not worth the effort because the 1.6 seems to work great with the stock transmission and clutch. I've been driving mine around all week on the 4 speed and it makes enough TQ everywhere to make the car very easy to drive, but not so much that it's hard to manage.
The benefit to a shorter stroke b6 dohc engine would be an improved rod ratio ( especially if longer rods were used with custom pistons). This would provide a more stable engine which could ( in theory) produce higher usable HP levels than the b6. I would like to build a destroked z series engine to test this, rather than a b series though. That's a topic for another thread.

[jhntu]

I've never seen one in person, but by the pictures and specs it looks like a b6d (Capri/Laser) with either a shorter stroke or smaller bore. I can't remember which is different. A destroked b6d would be fun in these cars, but probably not worth the effort because the 1.6 seems to work great with the stock transmission and clutch. I've been driving mine around all week on the 4 speed and it makes enough TQ everywhere to make the car very easy to drive, but not so much that it's hard to manage.
The benefit to a shorter stroke b6 dohc engine would be an improved rod ratio ( especially if longer rods were used with custom pistons). This would provide a more stable engine which could ( in theory) produce higher usable HP levels than the b6. I would like to build a destroked z series engine to test this, rather than a b series though. That's a topic for another thread.

Paging f3bz

[F3BZ]

well if your home is near my home it's out in the front yard and the hood is unlatched so feel free. as long as it runs good i have no plans to dig into it. it may be difficult to even source a valve cover gasket. a lot of parts are unique to the 1.3 BJ that do not cross to a B6D or B3. even the oil pan is different but that may just be baffled. the bore is the same as the B6D (78.0mm) and uses the same rings but the pistons are unique. some specs from wikipedia and other sources:
BJ - 87hp @ 7000 rpm. 72 ft/lb @ 4500 rpm. 78.0mm bore x 67.5mm stroke. 4.058 final drive ratio
B3 - 63hp @ 5500rpm. 75ft/lb @ 3500rpm. 71.0mm bore x 83.6mm stroke. 3.777 final drive ratio

[Advancedynamix]

If you ever do dig into it, I'd love to see what it's made of. Most likely a grab bag of other Mazda bits. The Capri b6d oil pan is baffled as well, but it's deeper (I think, but feel free to correct me) than the b3 pan.
Would (or have?) You please take some close up and detailed pictures of this rare gem of an engine and it's associated parts? Are you driving the gtx to madness?

[F3BZ]

gettin on it but as is common to all modern engines, all those tubes and wires and snug fit make things kinda murky below the head to pick up any details with a digicamera. more intriguing to me is the feat of engineering and cross linkage to mount the brake master cylinder/booster on the passenger side to clear the head.

[bhearts]

I'm curious about this, what could provide longer last high power production in a b6 setup. You say with the right intake the b6ze can rev to 7k, so I'm curious, for the same peak power numbers, would it be better turn the boost up and shift at 6k, or turn the boost down a bit a run to 7k

[bhearts]

For engine longevity, if it was the same engine in question

[Dragonhealer]

Lower rev's last longer, it's what makes forced induction so great!
To get 178whp on Carolyn's B61P normally aspirated,it gets shifted at 8100rpm because peek power is at 7300rpm.
I don't expect it to last more than a season.....
The mildest turbo setup will make better power at 6000rpm and last a very long time!

[jhntu]

We so need the like introduced into this.. So much like... Everywhere.