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Mazda 121 Fix up


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#1 Racemania

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Posted 28 May 2008 - 08:43 PM

First of all i thought i would post this up and let some ppl know what ive found so far with this car and motor.
PLEASE NO : Why would you bother with a B3 as i have already got all the crap from other forums :mellow:



The Mazda B3 engine is a smaller Block of the B6 and BP both of which can come with a turbo depending on model.
The B3 which i will talk about here is a 4cyl 1.3L 8 valve SOHC, you wont find many of these modified around the Streets but there is a few, i will explain how i have made some gains from a few mods to the car, all these are done on a budget.

Step 1: Getting better airflow into the manifold.
This is a hard thing for the carby cars i have modded my airbox to draw air from the front of the car, in my 121 i have a 4" gap between the body and the radiator of the car so i made up some pipes to route down to there its that hidden that you cant see it anymore, this dose not make the car much faster and just gives a cooler airflow from the front of the car it used to draw air from the front of the motor behind the drivers head light.

Step 2: upgrading the exhaust system. (yes even these cars sound better with good system)

mine i have a 2.25" system with a 4" cannon fitted to the rear, i was lucky and already had a 2.25" Cat and extractors on the car which didnt make sense to me as the old pipes from the cat back were only 1.5" which would have been putting a fair bit of presure on the system.

to tell you how loud this will make the car is way too hard so i have made a short vid on the sound i am getting (Warning this is not legal at all and if you drive with just this setup on your car you will face the police)
heres the vid

http://s47.photobuck...rrent=Movie.flv

those are not my number plates too old ones put on the car.

This kind of system will require a resinator or hotdog as some call them, this will bring it down to NSW laws for max dB from an exhaust system, it is 90dB for nsw or 96dB just depend who dose it EPA will test for 96 and the RTA and Police will test for 90dB which is required before it gets sent for EPA.

This system is off the car untill i can get the hotdog fitted which will be a few weeks away.
Benifits from this system for me are higher flowing air = more power not heaps but enough to spin wheels from 1st to 3rd, better sounds i had a lancer and skyline pull up next to me both thought they had nice sounding cars then i just give it a few bursts of RPM arround 4000 and they didnt bother anymore :biggrin:

ok im not braging here and this is a real good mod but will not make your car a super car to beat skylines and the sorts, this is just to show some ppl out there that these things can be done and will provide benifits to you and your car.

the now free flowing B3 idles arround 1100RPM and runs 98ron fule i havent done any dyno tests yet but i suspect about 10-20 extra HP from the car, not much but for this little 750Kg car it brings the Power to weight ratio up.

Step 3: this is a little bit of a harder thing to work with, Its the Clutch, i recomend you cange this due to the extra power you will be producing, i have just done mine and its was so bad i had to change the flywheel, if you can get a replacement box that will make it easier for you.
i wont go too much into this but if you have never changed a GB before then you may want to get someone to help you out, they are not that easy to replace local stores arround my area wanted anywhere from 400 to 1200 to replace the clutch, i done mine for just under 200 with all the parts needed.


General tune for the car.
on the carby motors they are suspect to a tapping noise from the rockers, this is common in the B motors from Mazda. you cant really do much about it other then replace the valves and rocker arms, i have not done this yet and it can be heard from the vid i posted up top.
use high grade engine oil i use 5w-30 this i have found runs well in the car, also upgrade the GB oil and use a treatment which you can get from auto stores for arround $7 i upgraded to high preformace oils and lubes and the car just loves it.
get a better thermostat this is critical as stock ones are crap and open way too early.
if you can get your rocker cover sandblasted and a nice look like this http://i47.photobuck...21/P4120354.jpg

you can set the timing advanced to about 10* my car seemed to like it if i moved it back it didnt have the power i was looking for, the valve clearance must be set perfect for the perfect power for the car its all hit and miss you need to spend a fair amount of time working on these 2 things to get the right tune from your car.

Carbys will need a clean often you can buy carby cleaner from auto parts store which will get rid of any gunk in the carby and will give it a new lease of life.

Rocker cover gasket: these are not real good you could get a replacement but i found something better its a gasket glue sort of thing its a copper based tube and will seal any area that has oil and water near it i used this with my gasket from the rockercover for a better seal it is a red coper color auto parts stores have these and will advise you on what you need.


Thats about all i can think of right now ill update as i do more work or if you have other things you know of let me know and ill add them.

if you have questions ask away i will do my best to help you out.

Thanks Racemania

Edited by Racemania, 29 May 2008 - 08:11 AM.

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#2 SuperMazdaKart

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Posted 28 May 2008 - 10:14 PM

maybe get a Holley carby :)

or maybe do it the more ghetto way, cut out the outer (in the area where it won't let unfiltered air get past the filter) curvey rectangular shapes in the air cleaner lid.
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#3 rodhog

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Posted 28 May 2008 - 10:59 PM

I say put a regind cam into and recurved ignition dizzy.

you only need a say 100Kw flywheel motor with that weight to turn it into a beast.
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#4 Racemania

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Posted 29 May 2008 - 08:08 AM

well im looking for upgraded cam for this motor but no one arround has any i think that would bring the power right up..

mazdakart nice idea but ive already made my air box ive got a forced Ram air from the bonnet straight to the carby WRX scoop style but that will not provide much more air then what im getting right now. so ive got some work to do.

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#5 rodhog

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Posted 30 May 2008 - 12:25 AM

would have to be a custom reground camshaft.
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#6 Racemania

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Posted 30 May 2008 - 07:26 PM

i think ill wait till the motor blows or somthing like that so then im not waisting money on the B3 and saving for the B6t conversion :))

i suspect getting a custom reground would cost a fair amount to get done?? any ideas on the price....

Thanks Racemania

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#7 rodhog

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Posted 30 May 2008 - 10:05 PM

yes they are expensive in terms of power out V cost. but it's the same for most N/A mods = unlike F/I where modifications can create double or more in comparison.

anywhere from $200 to $500 due to cost in development.

It's whyI search for similar motors etc to find ways around it.
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#8 Racemania

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Posted 31 May 2008 - 09:22 AM

yes they are expensive in terms of power out V cost. but it's the same for most N/A mods = unlike F/I where modifications can create double or more in comparison.

anywhere from $200 to $500 due to cost in development.

It's whyI search for similar motors etc to find ways around it.

ok well looks like ill wait till the B6t goes in after the B3 blows something up :thumbsup:

Thanks Racemania

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#9 Racemania

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Posted 31 May 2008 - 09:51 AM

some pics of my old clutch and new one

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as you can see its seen better days and needed replacing..

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#10 SP BLING

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Posted 31 May 2008 - 10:10 AM

I don't think that a 2.25" exhaust on a 1.3L engine will be good for the street. Yes you will have peak power in the higher rev range due to the large diameter, but you will comprise at lot of the low end torque with such a large system. Personally I would not have gone above 2" in pipe diameter.

As for easy mods:
  • Maybe look at upgrading the carb to another one from a slightly larger mazda engine. Maybe one from a B6 or even a owndraught weber?. More fuel/air = more powah.
  • Port/Polish the head using a die grinder
  • Have the head "shaved" to increase the compression ratio
  • Upgrade your ignition leads to larger/performance ones. This will give you a better spark.

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#11 Racemania

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Posted 31 May 2008 - 10:34 AM

I don't think that a 2.25" exhaust on a 1.3L engine will be good for the street. Yes you will have peak power in the higher rev range due to the large diameter, but you will comprise at lot of the low end torque with such a large system. Personally I would not have gone above 2" in pipe diameter.

As for easy mods:

  • Maybe look at upgrading the carb to another one from a slightly larger mazda engine. Maybe one from a B6 or even a owndraught weber?. More fuel/air = more powah.
  • Port/Polish the head using a die grinder
  • Have the head "shaved" to increase the compression ratio
  • Upgrade your ignition leads to larger/performance ones. This will give you a better spark.


yer looking for a carby soon just got to get off my bum and look for it :thumbsup:

as for the low end torque its still there better then it was before im still getting good jumps off the line i know the old carby is proberly going to slow me down soon due to the a/f Ratio and the head i will look into getting it shaved..

one thing ive found with the carby on my car is it has a fule injection on it i had asked arround at some workshops here about it and they all said that some cars did come with them i then went to mazda for some more info and the guy there said mazda was trying out a new type of system back then and had a electronicly injected carby running on some cars i dont know if this is true or not but if someone knows more about it can you let me know..

the leads have been upgraded but the plugs yet to be i may be going to get some better ones today was looking at some KLG Triple electrode ones or some bosh ones and a new coil as the old one wont keep up i think...

as said above this is never going to turn out to be a fast/ super car its just a budget upgrades for the best performance you can get... if that means running it on lower priced goodies then thats whats going to happen and best thing is it only has to last long enough to get me to a new motor.. :biggrin:

Thanks SP Bling for the info all info helps out :thumbsup:

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#12 Racemania

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Posted 04 June 2008 - 08:21 PM

ok ive encounted a few problems just small ones but im stumped with it so if you guys have any ideas throw them my way....

1. fule pump (mechanical) is leaking a small amount of fule when started in the morning im thinking maybe its broken or a seal is busted ?? but once the car is warm it stops.. so could it just be the cold weather that dose it??, its only happening when its cold if i leave the car and start it later in the day no leaks..

2. when driving it i get to arround 3500RPM and the car starts to surge but only lasts about 500 - 750 RPM after that everything is fine any ideas on that?? only happens when i like that short burst of power run ( usally at the lights when some noob in crap car wants to show his ride off)...???

and im getting shaking in the front end arround 70km/h to 90km/h but not when slowing down.. i was thinking cv joint but they are fine then i thought maybe i didnt tighten the swaybar up right but thats fine, so my next guess is either somthing not done up or as someone has said get a wheel alignment done and see if that fixes it..?? any ideas on these??

thanks Racemania

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#13 SuperMazdaKart

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Posted 04 June 2008 - 08:31 PM

had the exact same thing happen with my fuel pump on the 121 years ago. the diaphragm or something inside contracts too much when cold. was told that they aren't manufactured anymore so not much chance getting a new one, & if you do won't be cheap. ended up having a WA Festiva pump put on from an auto wrecker.

power surge? maybe it's that rev point when the camshaft ticks over into higher power? dunno..

when was the last wheel alignment done? i seem to remember something similar with mine but didn't go away completely with a wheel alignment. these are budget econo cars with uneven length driveshafts so maybe have to accept it as a symptom of front wheel drives. having said that though, get the wheels balanced during the alignment..

Edited by SuperMazdaKart, 04 June 2008 - 08:38 PM.

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#14 Racemania

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Posted 04 June 2008 - 09:56 PM

had the exact same thing happen with my fuel pump on the 121 years ago. the diaphragm or something inside contracts too much when cold. was told that they aren't manufactured anymore so not much chance getting a new one, & if you do won't be cheap. ended up having a WA Festiva pump put on from an auto wrecker.

power surge? maybe it's that rev point when the camshaft ticks over into higher power? dunno..

when was the last wheel alignment done? i seem to remember something similar with mine but didn't go away completely with a wheel alignment. these are budget econo cars with uneven length driveshafts so maybe have to accept it as a symptom of front wheel drives. having said that though, get the wheels balanced during the alignment..


ok so its something inside it ill go to the wreckers and see what i can come up with. should have kept the one off the 808 motor was brand new :(

cam ticks into power mode well i can handle that :)

sp_bling has mentioned that a wheel balance may be needed i had new tires put on 2 weeks ago but i might have knocked off one of the weights, the car has never done it before just feels awful when trying to drive on the highway so i will get it checked with the wheel alignment.

Thanks Racemania

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#15 Racemania

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Posted 07 June 2008 - 07:15 PM

just took the car out for a run today to see what it was like on the open road ended up doing just on 200k for the day.

we left arround 9am for wangaratta down the hume highway, car ran real well used to be you could only go about 90km/h and today the car felt really good about doing 110km/h it even pushed for 130 when i needed to overtake a noob driving a bmw so.

the shakes in the front end have seemed to dissapear now?? i dont know what caused them or where they went.

i fuled up this morning with normal unleaded 27L and added a octane boost to the tank when we got to wang we had done just on 60k and the fule hadent moved off the full line, i was happy with that as for me to go to winton it would cost me arround $10 to get there :)) when we got home the fule was on just above the 3/4 mark which would cost me about $15 to fill back up :-) so im happy with the car so far seems some of the tuning i have done on the motor has helped out heaps.

one thing i noticed with the car is the sound of the exhaust was getting more sound the more we drove stock mufler on the rear and a 2.25" pipe from the cat to the mufler, a mate said the exhaust takes about 200k to wear in not sure if this is true or not but its been about 400km since it was fitted.

ok thats about all other then when i was in beechworth there was some nice mazdas there a MX5 with some nice work on it couldnt get a pic was too fast. and there was a RX8 with number plate D4SSED i think it was Blue with big 19" rims or 18" was nice. there was also a few MPS 6 and 3's there too looked like they all knew eachother as they all left together. maybe another mazda club ??

Thanks Racemania

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#16 SuperMazdaKart

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Posted 14 July 2008 - 03:22 PM

i was just looking through Festiva Motorsports website for ol times sake & they have a competition camshaft.. wonder how long they've had them for. on special at $149 US with free shipping.

not really worth it to me though :)
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#17 chief tool

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Posted 25 October 2008 - 06:46 PM

Sorry for reviving an old post but I am new on this site anyway, and I found it interesting to see someone do what I did some time back.

I had a WA festiva tho, and there are a few differences between it and the 121 (if anyone is interested) as my sister owned an 88 121 at the same time,so I could drive both and compare.

The festiva had an exahust manifold 4 >1 whereas the 121 had a 4>2>1 arrangement....I bolted this on onto my festiva and noticed an small improvement in midrange torque.

The valve timing in the 121 is quite different to the festiva....theyre quite different cars on the road, I ended up putting a B6i camshaft in my festiva (another small improvement) but the festiva always seemed to have more bottom end torque than the 121, the 121 seemed to rev harder. could have been cam advance, I played around with the cam timing (using the different positons of the cam wheel) until it went the best on road via the seat of the pants dyno

Another thing I found i that the festiva always had mild pinging from the factory, eve with the ig timing set to factory settings....on 91 octane...I found running it on 98 not only made a noticeable improvement on the road, but the car uised less fuel and was smoother...I then increased the static timing to as much as it would take. this was the biggest improvement.

I found too that the factory manifolds are poorly matched, like off by as much as 5mm on one port in the exhaust. port matching is a good idea.

all in all....the best thing you can do is fit an 8v B6....I knew a guy who did it, and the difference...well worth it.

And install the stiffest rear springs you can handle.....and you'll suprise a few cars in the handling dept

Edited by chief tool, 25 October 2008 - 06:48 PM.


#18 burg323

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Posted 26 October 2008 - 07:15 AM

more power from a Mazda 121?..... dont bother, buy another car if power is a requirement.

Why waste time with such a slug....... i could imagine even after fitting a turbo you might get your 1/4 mile times down from 20secs to 16secs?

#19 Racemania

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Posted 04 November 2008 - 01:25 PM

lol been a while since ive visited .....

anyway ive been really busy with other stuff but the 121 is on the road atm and driving well, power aint a problem the car has plenty of power atm just caps out at arround 7000rpm i went to a mazda bloke who had some books and stuff on timings showed me what to set it at all worked out good no tapping in the rocker anymore and the car picks up speed right away, its amazing how much a little bit of work and cleaning can help a car run smooth again.

ohh and the exhaust mod i done to it has improved fule econ big time, we do 1 full tank in a week with arround 600kms done as before i done anything we were lucky to get 500k on the tank.

no fines for noise yet but then i dont open it up that much arround town, only on the highway or when wanting to get somewhere quick.

thanks for your replys

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#20 Racemania

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Posted 14 April 2010 - 08:49 PM

Hey, so been a long long time since i visited, had lots of things happen in almost 1 1/2 years, but good to say the car is still going strong.

So im here to let everyone know in a few weeks/months this beast might be on the market as with my 626, i just dont seem to have the time or the skills to work on either anymore.

Not 100% on giving up the 121 but im looking at another project car to work on which may take up the shed space for a year or so.

Anyway good to see Ozmazda is still going strong.

Cheers.

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