adjustable rev limiter??

Joey's mx · Post by **Joey's mx** » December 7th, 2006, 7:41 pm

Ok i have heard of systems that ables you to play with the rev limiter(msd...) Will they work on a 94 dohc b6?? Are they acually good to use?? Where could i find them??

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 8th, 2006, 1:26 pm

hey, i was wondering the same thing. Do you mean the MSD6al that the adjustable rev limiter? my buddy said they work. He works at karbelt. Come theres got to be somebody that has done this to their 94?

Yoda · Post by **Yoda** » December 8th, 2006, 3:12 pm

Unless the device can intercept and modify the tach signal to the ECU the OE rev limiter will still kick in at the same point. The only way to modify the OE limiter parameter is to re-flash the ECU since there is no separated EPROM in ECU for the DOCH. Devices like the MSD 6AL can be set below the factory redline. Anyway there is no real point to raising the factory redline unless you have change to more aggressive cams or you can't shift and need the extra time to find the next gear. The higher you rev over the peak HP rpm the farther down the downhill side of the power curve you will be before.shifting into the next gear. To get the most out of the power band of your car, your goal would be to start your shift a couple hundred rpm before the peak HP rpm by the time you're in the next gear you should be just over this rpm. This being the case you should be always about a 1000 rpm short of redline and minimizing the time you are slowing down on the downhill side of the power curve. In racing this is called short shifting.

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 8th, 2006, 3:21 pm

well seeing that im putting the miata cams in when i do my timing belt water pump and rocker cover gasket. How would you go about reflashing the ECU. It would really be nice to take first up to 7500 as 1-2 is very wide and way below the powerband. It would be nice to catch 2nd just before VICS engages. Does reflashing it mean i would have to send in to someone? or is there a protege or something that uses the b6DOHC and has higher rev-limiter? a J-SPEC ecu? is there even one? how hard would it be to switch to external coil like the miatas? could i use the distributor, coil(s), ECU out of the miata and switch to external coil. The reason im asking so many questions is because you seem very knowledgeable from the other posts ive read. Plus theres a 90 miata B6 at the wreckers so if i could use that ECU and ignition setup while still utilizing my harness?Because im not going to put the miata cams in until i can utilize their powerband, as it sucks having a even pull with a car and u having to shift at 90 while they keep using their momentum and take it up to 100 and then catch rd at close to peak power

Yoda · Post by **Yoda** » December 8th, 2006, 9:35 pm

The only people that can reflash the MX-3 ECU is the Mazda dealers. Not much chance of that happening. There is no such thing as a JDM B6 DOHC except for the MX-5 and the N/A 323 AWD but that was only a SOHC. Even the B5-ZE that makes 120hp has the same redline as the US spec B6-DE. If you are going to convert to a DCI forget about cobbling together that miata system. At that point you might as well go to a stand alone system you will be much further ahead.

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 11th, 2006, 12:23 pm

thanks for all the quick replies. what about a megasquirt is it possible on the b6de? or could a piggy back do the job, like can you adjust the rev limiter on a piggy back? what other tuning can you do with a piggy back? or do u need to be forced induction? a stand alone seems expensive which would mean i could get a BP swapped and have my problem solved. any way with splicing wires that another ECU will work? the longer i think about the better a BP swap is sounding to me everyday...lol but i want to keep the b6 and mod it with mods i could carry over to a BP, but when i do a BP i want the g-series tranny too so its really not in my budget right now as it would be upwards of 1000$ with a clutch flywheel,trans,2nd gen BP, etc.

94blaze1.6 · Post by **94blaze1.6** » December 11th, 2006, 5:26 pm

The 2nd gen bp is actually lower tech then the first gen, although it is easier to install in the 94-96 models. The newer bp has a lower hp rating, "It also features a cast crankshaft, no oil squirters, a plastic oil pickup tube and less aggressive camshafts. It is found in the 1995-1998 Mazda Protege ES" <--from the wiki page. Now you shoud ask yourself if you really want this engine, or on the other hand you could still swap the 1st gen bp but then you are swapping an older engine in a newer car with some splicing....In my opinion building up the b6d is a good idea as there are a lot of miata performance parts you could use (as you already know). I just think its kinda fun seeing what our engines can do rather then swapping.

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 11th, 2006, 5:35 pm

thanks, i definatly agree i love this little car and the engine has given no problems at all, i just wish there was a way cheaper than 500$ to move up or get rid of the stupid econobox revlimiter. i wonder if a 2nd gen bp ecu will work with even some wire splicing, as you can use the bp ecu with the sohc b6. or if piggy back allows you to adjust the rev limiter and if it can be used on N/A car...i dont see y not. or mega squirt...lol i have no idea.

94blaze1.6 · Post by **94blaze1.6** » December 11th, 2006, 6:02 pm

Standalone can be used with NA engines and cab be pretty beneficial. Limegreen was running it for a while on NA bp. The thing about raising the rev limit is why would you want to do it on engine that produces the MOST power before or at redline. Reving this engine further will not be beneficial as a matter of fact you will get LESS power. If you build the engine to have more power at a higher redline then you will need to change it. No point in doing it now.

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 11th, 2006, 6:41 pm

well the reason i want to raise the rev limiter is because it makes its peak horsepower at 6300 rpms stock, with the cold air intake, gutted cat and muffler the power band would be moved to a higher rpm range. especially once i get the headers and miata cams installed. but even without those two my peakhorsepower should be 110-115(crank) at around 6500-7000 rpms. so i possibly could hit the rev limiter well before i even reach peak horsepower, and the cams and header are going to be on when it goes back on the road and that will move my powerband even higher. plus since you have the DOHC wouldnt you like to be able to keep it in first a bit longer to catch 2nd a little higher in the revs.

WingleBeast · Post by **WingleBeast** » December 11th, 2006, 6:46 pm

yeha but the newer BP has a knock sensor, useing air/fuel mapping instead of percentages/ and better OBD

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 11th, 2006, 6:48 pm

what are you trying to say about the new bp?

94blaze1.6 · Post by **94blaze1.6** » December 11th, 2006, 7:53 pm

mzdamx3rsdohc wrote:well the reason i want to raise the rev limiter is because it makes its peak horsepower at 6300 rpms stock, with the cold air intake, gutted cat and muffler the power band would be moved to a higher rpm range. especially once i get the headers and miata cams installed. but even without those two my peakhorsepower should be 110-115(crank) at around 6500-7000 rpms. so i possibly could hit the rev limiter well before i even reach peak horsepower, and the cams and header are going to be on when it goes back on the road and that will move my powerband even higher. plus since you have the DOHC wouldnt you like to be able to keep it in first a bit longer to catch 2nd a little higher in the revs.

So you are saying that because u got a cai your peak hp changed to 200-700 rpm higher then stock? I doubt it

mzdamx3rsdohc · Post by **mzdamx3rsdohc** » December 11th, 2006, 10:45 pm

actually im saying that with a gutted cat and 21/4 inch catback and cold air intake will raise the powerband in the RPM range. considering my car wont be on the road until march when ill also have the miata cams and header installed that a 6700 rev limiter is way to low.

WingleBeast · Post by **WingleBeast** » December 12th, 2006, 1:16 pm

im saying the new BP isnt lower tech, its just more economy in its stock form. its higher tech, with a computer system set up for better horsepower with air/fuel mapping. if you put new camshafts in it, and swaped out for a forger crank, plus change the platic stuff over, its alot better as far a tuneing is concerned