Rod ratio importance is debatable. Really depends on the engine. My thoughts are, a high rod ratio decreases piston speed. No one is revving the BP high enough to worry about out running the flame front, however there are other benefits to this. We all know the BP's head doesnt flow the greatest. As RPMs, and thus piston speed increases, air velocity increases; a weak point for the BP head. Slowing piston speed should really help in the respect. On the negative side, there's a proportional increase in TDC dwell time, which may cause issues, I don't know.
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I don't think a stock head would flow well enough to see much of a difference between 25 and 30 lbs. Might want an IAT probe and take it up slow on the dyno. From everything I've seen that'll be right around the limit. No personal experience though.sigpic
1992 Familia GT-X
1988 323 GTX
2011 F150 Lariat Ecoboost
2014 Civic Touring
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An engine with a better rod ratio (FE3, 2.0/2.3MZR) has less side loading and less friction then one with a lower ratio (BP, 2.5 MZR)
Yes the BP can rev fine to 8K but there is more stress on the bottem end then a FE3 at 8K for example. There is more potential for more power/less fuel consumption with the better ratio. Mazda tried to address this with its new 2.5 MZR by putting a coating on the piston sleeve/liner to reduce friction since it has a worse rod ratio then a BP does. Goodwin racing has a Miata with a World Challenge built 2.5 that revs safely to the 7800 RPM rev limit and makes 270WHP, so the bad rod ratio can be revved if the bottom end can handle it.
There is always a trade off though, lower piston speed does not breathe as well at lower RPM as higher piston speed on the same size port.
My personal theory is this:
high rod ratio=slower piston speed=head with smaller ports (MZR 2.0)
low rod ratio=faster piston speed=head with large ports (MZR 2.5)
Again its only my theory and have no way to prove it at this point.
Bottom line is this though, the BP is fine for the job intended (turbo power), and it can make N/A power but its not ideal and is more work. The bottom end is strong enough to take it.
Rod ratios:
BP-1.54
FE3-1.74
MZR 2.0-1.86
MZR 2.3-1.64
MZR 2.3 DISI-1.60
MZR 2.5-1.5192 Mazda MX3 GS> For sale, $1750 OBO
94 Escort wagon--BP swap coming, VF10 Turbo, COP, EVO ECU, 03 ZX2 front end conversion
"Hold yourself accountable before you are held accountable"
EV14 330cc@3Bar injector kits available.
EV14 GT500 injector kits available for the BP. 610cc@3Bar.
EV14 925cc@3Bar injector kits available
BP Forged H beam rods available now
KL Forged H beam rods available now
K8/KF Forged H beam rods awaiting test fit
FS Forged H beam rods awaiting test fit
F2 Forged H beam rods awaiting test fit
FE3 Forged H beam rods coming soon
Mitsubishi 3.8 MIVEC rods coming soon
Aluminum CAS/Distributor caps
BP oil jet eliminators
EV14 fuel rail spacers
More stuff coming soon.......
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Originally posted by atomicEGT View Poststock head is fine at 7500, OP gears aren't.
Yeah, I forgot about the oil pump gears. Those are the only things I am worried about when running my engine at 8000 rpm. I wish billet gears were in my budget. Although, that gives me an idea.... Maybe I can make a set myself at school on the cnc machine.My family has lots of bg's!
2003 Ford Escort ZX2: Project car/future daily driver. Built Ford Tough (With Mazda Stuff)
1999 Escort ZX2: Daily driver/beater. Going to be replaced by the '03 next summer.
2000 Escort ZX2 S/R: bought wrecked, going to use as parts car
1992 Protege LX: My old race car. Just a wrecked shell right now. Waiting for scrap to go up so that I can get rid of it.
1992 Mazda 323: Race car
1992 Escort Gt: My grandpa's old race car
1994 Escort GT: My grandpa's new race car.
Parts cars; 1993 Escort Gt, 1995 Escort lx
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So tell me, what could I get for a escort 1.9motor, 5spd trans and all harnesses?
Because I find 5spd wagons all over for good prices but it would be converted to either an auto bp or auto kl so I would have to convert all those harnesses and **** anyways.Last edited by Turpro; 10-15-2012, 09:35 AM.1993 Protege LX-Midnight's shadow SOLD
1996 Honda CBR600-Wrecked. Damn Honda crippled me
2002 mazda MPV-family truckster SOLD
2010 VW routon
Originally posted by jay.....they totally underestimated the number of gearheads such as myself that have families but refuse to grow the hell up and stop playing with cars, or that otherwise see the utility of having 4 doors. Obviously I ain't alone, as there are a helluva lotta sti and evo here. Bueler? Beuler? Mazda? Mazda?
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Even on feoa?1993 Protege LX-Midnight's shadow SOLD
1996 Honda CBR600-Wrecked. Damn Honda crippled me
2002 mazda MPV-family truckster SOLD
2010 VW routon
Originally posted by jay.....they totally underestimated the number of gearheads such as myself that have families but refuse to grow the hell up and stop playing with cars, or that otherwise see the utility of having 4 doors. Obviously I ain't alone, as there are a helluva lotta sti and evo here. Bueler? Beuler? Mazda? Mazda?
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You will have better luck selling it on feoa but everyone will want it for nothing, but I did manage to sell all the parts needed for a auto-5spd coversion locally for about $140. It took a while to sell though. I am sure you could get about $200-300 for a running engine, especially since they have the valve seat issue and people are always looking for one.
Since my engine swap my airbag light flashes, but i have never bothered to find out why. One of these days i will get to it though.92 Mazda MX3 GS> For sale, $1750 OBO
94 Escort wagon--BP swap coming, VF10 Turbo, COP, EVO ECU, 03 ZX2 front end conversion
"Hold yourself accountable before you are held accountable"
EV14 330cc@3Bar injector kits available.
EV14 GT500 injector kits available for the BP. 610cc@3Bar.
EV14 925cc@3Bar injector kits available
BP Forged H beam rods available now
KL Forged H beam rods available now
K8/KF Forged H beam rods awaiting test fit
FS Forged H beam rods awaiting test fit
F2 Forged H beam rods awaiting test fit
FE3 Forged H beam rods coming soon
Mitsubishi 3.8 MIVEC rods coming soon
Aluminum CAS/Distributor caps
BP oil jet eliminators
EV14 fuel rail spacers
More stuff coming soon.......
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Just checked the wiring manual. Apparently the GT never came with airbags?
The schematic says "1.9L only" but it appears the only thing that would be missing to make it work is an airbag fuse located in the engine compartment fuse box that I know for sure the GT fuse box does not have.
It supplies the R/W wire going to the airbag module with 12v constant. I will check it out tomorrow if I get time.92 Mazda MX3 GS> For sale, $1750 OBO
94 Escort wagon--BP swap coming, VF10 Turbo, COP, EVO ECU, 03 ZX2 front end conversion
"Hold yourself accountable before you are held accountable"
EV14 330cc@3Bar injector kits available.
EV14 GT500 injector kits available for the BP. 610cc@3Bar.
EV14 925cc@3Bar injector kits available
BP Forged H beam rods available now
KL Forged H beam rods available now
K8/KF Forged H beam rods awaiting test fit
FS Forged H beam rods awaiting test fit
F2 Forged H beam rods awaiting test fit
FE3 Forged H beam rods coming soon
Mitsubishi 3.8 MIVEC rods coming soon
Aluminum CAS/Distributor caps
BP oil jet eliminators
EV14 fuel rail spacers
More stuff coming soon.......
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