4-2-1 exhaust manifold good idea? and question about gearbox oil

[tau9]

Hi, I'd like to get better performance on my car and I was thinking on switching the exhaust manifold to a 4-2-1. I have no catalyst.

Something like this for example

http://www.ebay.com.au/itm/FORD-LASE...-/151112111508

It's a good idea to do that? I want to gain performance on the low and mid range and still maintain the same performance on high rpm.

Also I have another question, should I replace the gearbox oil with 150.000-160.000 kms (assuming that gearbox oil has never been replaced).

thank you for your comments!

[HMT]

If you have time and money to spare, you could change the gearbox oil. However, if you're not experiencing any problems, it's really not an urgent task.
You might be facing a clutch change in the somewhat near future and can save the oil change until then...

[tau9]

Originally Posted by HMT

If you have time and money to spare, you could change the gearbox oil. However, if you're not experiencing any problems, it's really not an urgent task.
You might be facing a clutch change in the somewhat near future and can save the oil change until then...

I have no problems with the gearbox, I just have hear that replacing the gearbox oil can make the car run better that's why I was wondering if replace or not the gearbox oil.

I'll wait until I have to replace the clutch to do that. Thank you.

[rodhog]

yeah I'd wait till you do a clutch.

Most cars only change the Gearbox oil when doing clutch. It's not something that is changed often in a street car.

Improve performance - NO- not directly. Improve shift quality and smoothness - reduced noise etc. YES

Just like your engine enjoys a good fresh does of oil.

Gearbox does too but you don't have the contaminates from exhaust and fuel mixing with the oil.

If you do lots of HI -speed constant long driving then yeah you would change it more often. But normal use - you should be able to do it only when changing the clutch.

[TheMAN]

better gear oil reduces wear and friction, changing it out won't hurt and it may drain out the wear metals

I recommend only Red Line MT90 and the Motul equivalent in GL4 75W90 spec... both of which are synthetic and helps immensely

the 4-2-1 exhaust manifold greatly improves power and fuel efficiency... do it!

[Old Grey]

For what you want, that exh looks too big in diameter.

Do you know how to fabricate headers, ie, welding, or do you have to buy them.

[project.r.racing]

just looks like a normal set of 4-2-1 aftermaket headers to me. looks very similar to mine.

i'd change the gearbox fluids if they've never been done.

[Doctor Shifty]

Gear box oil gets changed for a reason. Although it lasts longer than engine oil and has no contaminants getting into it, the additives do not last forever.

Because the gearbox has bevel (spiral) gears, the teeth slide sideways over each other and this action needs cushioning. The additives are soft microfine phosphorous/sulfurous compounds that lubricate the gears like teflon or graphite particles lubricate surfaces.

As the gearbox works normally, these particles are slowly being ground away. When they are gone the oil needs to be replaced. Different grades of gear oil, normally GL-4 and GL-5, have varying amounts of additives.

Chase up wikipedia or lubrication sites to learn the finer points of what makes a dedicated gear oil as opposed to engine oil.

[TheMAN]

it's called extreme pressure additives.... they're typically sulphur
but shearing forces will also thin out the oil, as will heat cycling... a bad gear oil will lead to elevated bearing temperatures and more metal to metal contact in bearings and gears... this isn't good for gearbox longevity

[Old Grey]

Originally Posted by project.r.racing

just looks like a normal set of 4-2-1 aftermaket headers to me. looks very similar to mine.

To the untrained eye that's exactly right, to someone with 30 years of engine design experience it looks too big - big pipes are a very common mistake -.

As a guideline:-
The lower the rpm you want the peak power the smaller the diameter and the longer the length.
The higher the VE - more power -, the smaller the diameter and the shorter the length.

Why is piping(manifolds) so important?
No NA engine can achieve a VE higher than 100% without inertia and wave tuning, but because engines can achieve VE's in the 125-130% range you are ignoring 25-30% of an engines power by ignoring the manifolds.

To give you an example of 4 into 1 pipes:-
1.8 BP(B8) SOHC making 103hp@6000 needs 1.35" dia 31" long
1.8 BP(B8) SOHC making peak at 3000 rpm needs 1" dia 63" long
1.8 BP(BP) DOHC making 160hp@6000 needs 1.25" dia 27" long

It's hard to tell from the pic but they look like 1.75" dia x 15" x 15". Length looks like it tunes at 6000 rpm, but the dia wants to tune at 9000rpm - remember you have to shift 300-500 rpm higher on a track - and a hyd lifter engine would have problems at that rpm.

[TheMAN]

the pics aren't very good so it's hard to tell the pipe sizing IMO, but you are right that pipe sizing is a big deal... you need to take advantage of the pressure waves in order to promote scavenging, but in order to do that, correct pipe sizing is necessary based on the engine's characteristics... of course you already know, it is different from engine to engine

[rodhog]

They are just Hurricane /old Liverpool exhaust headers. Copys of Genie and others. Nothing spectacular. Size will be okay. Plus I'd almost say a generic photo.

I'd also say possibly from batch they made 20 years ago.

[tau9]

Reading your comments I see it's not that easy to achieve more horsepower by replacing the exhaust manifold.

What 4-2-1 exhaust manifold do you recommend?

Or shall I go to a specialised exhaust manifold workshop so they can make a manifold specifically for my mazda?

Where I can read more about exhaust manifold design?

[TheMAN]

the simplest answer I can give you:

cheap, performance, reliability

you can ONLY pick two out of the three
this rule of thumb generally applies to everything else in life too


so with that in mind, custom made? be prepared to spend at least 500 euros for a well made piece... there's several different brands of premade ones out there and only 3 that are good.... autoexe (made by maxim works), AWR, and mazdaspeed... all 3 are expensive and cost $500 USD

if you're on a budget, there's nothing wrong with getting the cheap crap... just don't expect it to last forever nor expect it to give you the best performance.... they will still give you a decent performance increase over your stock manifold system

[Old Grey]

Originally Posted by tau9

Reading your comments I see it's not that easy to achieve more horsepower by replacing the exhaust manifold.

What 4-2-1 exhaust manifold do you recommend?

Or shall I go to a specialised exhaust manifold workshop so they can make a manifold specifically for my mazda?

Where I can read more about exhaust manifold design?

No body is going to have what you need on a shelf because of the problem of public perception. Basically they will never be able to sell 1" pipes when there is a set of 1¾" pipes next to them, because the uninformed public will always pick the bigger pipes even though the 1" pipes are better - bigger is always better mentality -.

Custom pipes are the way to go, but the problem is that most exhaust shops don't know how to design pipes - they usually just copy what they see -, so you will probably end up with something similar to those ebay pipes if you leave it to them.

I can design pipes for you, if you give me a few specs, but I think most custom pipes will be expensive. You can get pipes quoted based on my dimensions just to see if it's viable - this is why I asked if you knew how to fabricate pipes -.

Otherwise look for the smallest shelf pipes that look the same length as those ebay pipes. The 3 examples previously will allow you to make an approximation of sizes.

I'll tell you a story that highlights what pipes can do.
A customer that races hillclimb with the Triumph club came in to get his cyl head serviced, a 70's Triumph Dolomite with a 1.8 16V SOHC engine. Because he races, I told him to bring in the int and exh manifolds to see if I can find an area to improve. Straight away I saw that the pipes were too big, and that he would definitely pick up power with smaller pipes. So I calculated the dimensions and gave them to him. He went to his exhaust guy, a guy that is supposed to be an expert in Triumph pipes because his pipes are on every car in the club, and straight away he said the sizes were all wrong, ie too small, and that they would never work. The owner stuck to his guns and said make them anyway. A week latter the owner comes in and said he made 6hp more, which is a lot for such a small motor, but the kicker was that he picked every where else. The engine picked up 20hp in the mid range, which is massive for a 125hp motor, and went from a mid field car to 2nd fastest in the club - the other kicker was the car that beat him had a turbo -.

I will guarantee that those ebay pipes will reduce low rpm throttle response for a touch more power up high.

[tau9]

Originally Posted by TheMAN

the simplest answer I can give you:

cheap, performance, reliability

you can ONLY pick two out of the three
this rule of thumb generally applies to everything else in life too


so with that in mind, custom made? be prepared to spend at least 500 euros for a well made piece... there's several different brands of premade ones out there and only 3 that are good.... autoexe (made by maxim works), AWR, and mazdaspeed... all 3 are expensive and cost $500 USD

if you're on a budget, there's nothing wrong with getting the cheap crap... just don't expect it to last forever nor expect it to give you the best performance.... they will still give you a decent performance increase over your stock manifold system

I prefer reliability and performance. Thank you for telling the good exhaust manifold brands for the astina.

Originally Posted by Old Grey

No body is going to have what you need on a shelf because of the problem of public perception. Basically they will never be able to sell 1" pipes when there is a set of 1¾" pipes next to them, because the uninformed public will always pick the bigger pipes even though the 1" pipes are better - bigger is always better mentality -.

Custom pipes are the way to go, but the problem is that most exhaust shops don't know how to design pipes - they usually just copy what they see -, so you will probably end up with something similar to those ebay pipes if you leave it to them.

I can design pipes for you, if you give me a few specs, but I think most custom pipes will be expensive. You can get pipes quoted based on my dimensions just to see if it's viable - this is why I asked if you knew how to fabricate pipes -.

Otherwise look for the smallest shelf pipes that look the same length as those ebay pipes. The 3 examples previously will allow you to make an approximation of sizes.

I'll tell you a story that highlights what pipes can do.
A customer that races hillclimb with the Triumph club came in to get his cyl head serviced, a 70's Triumph Dolomite with a 1.8 16V SOHC engine. Because he races, I told him to bring in the int and exh manifolds to see if I can find an area to improve. Straight away I saw that the pipes were too big, and that he would definitely pick up power with smaller pipes. So I calculated the dimensions and gave them to him. He went to his exhaust guy, a guy that is supposed to be an expert in Triumph pipes because his pipes are on every car in the club, and straight away he said the sizes were all wrong, ie too small, and that they would never work. The owner stuck to his guns and said make them anyway. A week latter the owner comes in and said he made 6hp more, which is a lot for such a small motor, but the kicker was that he picked every where else. The engine picked up 20hp in the mid range, which is massive for a 125hp motor, and went from a mid field car to 2nd fastest in the club - the other kicker was the car that beat him had a turbo -.

I will guarantee that those ebay pipes will reduce low rpm throttle response for a touch more power up high.

Thank you for your explanation, now I understand this more clearly.

Can I ask you for the pipes design? What specs you need? The engine is the 1.8 16v BP (101kw accoding to car documentation) and I want mid range improvement and, if possible, some little gains at high rpm (street use). I'll find myself someone to make the pipes according your specs, here there are some workshops that make handmade exhaust manifolds.

As a curiosity. Where did you learn to design exhaust pipes? Is there any book that explains that? I'd like to learn more.

thank you so much!

[Old Grey]

Hp and at what rpm
Bore
Stroke
Rod length
Comp
--------------------------
INLET
valve size
Cam valve lift
Duration @ 0.050"
Degreed centerline
Seperation angle
--------------------------
EXHAUST
valve size
Cam valve lift
Duration @ 0.050"

Is the engine one of these
http://www.protegefaq.net/

I think your bottom end is the same as my BP SOHC so it should be 83 x 85.
If you can't get cam specs I will use my SOHC ones, they are close enough.

The important question is a what rpm do you want the peak hp. When you race you will have to shift 500rpm higher for the fastest time, so there is some flexibility. Remember also that the hp trace is a curve, so that after that point it drops. If you pick 3000rpm it will be brilliant around there but maybe down a bit at top- if the pipes have good turns it might not lose much at all -. 96% of my driving is under 3500 with higher rpm only for overtaking.

[tau9]

Originally Posted by Old Grey

Hp and at what rpm
Bore
Stroke
Rod length
Comp
--------------------------
INLET
valve size
Cam valve lift
Duration @ 0.050"
Degreed centerline
Seperation angle
--------------------------
EXHAUST
valve size
Cam valve lift
Duration @ 0.050"

Is the engine one of these
http://www.protegefaq.net/

I think your bottom end is the same as my BP SOHC so it should be 83 x 85.
If you can't get cam specs I will use my SOHC ones, they are close enough.

The important question is a what rpm do you want the peak hp. When you race you will have to shift 500rpm higher for the fastest time, so there is some flexibility. Remember also that the hp trace is a curve, so that after that point it drops. If you pick 3000rpm it will be brilliant around there but maybe down a bit at top- if the pipes have good turns it might not lose much at all -. 96% of my driving is under 3500 with higher rpm only for overtaking.

If i'm not wrong the engine is the BP-ZE (Europe Leaded Fuel/G.C.C.)of the protegefaq page, the 138hp version (car documentation says it has 101kw=137-138hp, built in the year 1990). Where I can find the engine code to confirm the exact version of the engine?

About the hp increase, I'll like to gain in the mid range around 3000-4500rpm... Choose what you think is better, what your experience tells. I don't know if it's better to make the gain when the VICS system activates or just ignore it. Do you recommend to also add better cams with the new ex manifold or stock cams will do fine (agressive cams can make the idle be unstable or to high, i'm not interested on this because car has to be street usable and pass the inspection, I'm lucky the astinas are not known in my country xD).

[Old Grey]

I had to fudge some numbers, because the specs aren't on the web, but they should be close enough

I gave you a range, so pick one or interpolate what you want.

Peak 6800 rpm
Range 4800 to 7300 RPM
1st Segment 1.471" dia - Length 12.6" to 13.9"
2nd Segment 1.570" dia - Length 12.6" to 13.9"
Collector 2.270" to 2.520" Lengths 15.7"(best) or 7.8" or 31.4"
Best HP/TQ Total Exhaust System Lengths 15.7 , 31.4 , 62.7 , 125.5"

Peak 6500 rpm
Range 4500 to 7000 RPM
1st Segment 1.439" dia - Length 13.2" to 14.5"
2nd Segment 1.570" dia - Length 13.2" to 14.5"
Collector 2.214" to 2.464" Lengths 16.4"(best) or 8.2" or 32.8"
Best HP/TQ Total Exhaust System Lengths 16.4 , 32.8 , 65.6 , 131.3"

Peak 6200 rpm
Range 4200 to 6700 RPM
1st Segment 1.405" dia - Length 13.9" to 15.2"
2nd Segment 1.530" dia - Length 13.9" to 15.2"
Collector 2.156" to 2.406" Lengths 17.2"(best) or 8.6" or 34.4"
Best HP/TQ Total Exhaust System Lengths 17.2 , 34.4 , 68.8 , 137.6"

Peak 5900 rpm
Range 3900 to 6400 RPM
1st Segment 1.371" dia - Length 14.6" to 16"
2nd Segment 1.496" dia - Length 14.6" to 16"
Collector 2.098" to 2.348" Lengths 18.1"(best) or 9.0" or 36.1"
Best HP/TQ Total Exhaust System Lengths 18.1 , 36.1 , 72.3 , 144.6"

Peak 5600 rpm
Range 3600 to 6100 RPM
1st Segment 1.335" dia - Length 15.5" to 16.9"
2nd Segment 1.460" dia - Length 15.5" to 16.9"
Collector 2.037" to 2.287" Lengths 19"(best) or 9.5" or 38.1"
Best HP/TQ Total Exhaust System Lengths 19 , 38.1 , 76.2 , 152.3"

Peak 5300 rpm
Range 3300 to 5800 RPM
1st Segment 1.299" dia - Length 16.5" to 17.8"
2nd Segment 1.424" dia - Length 16.5" to 17.8"
Collector 1.975" to 2.225" Lengths 20.1"(best) or 10.1" or 40.2"
Best HP/TQ Total Exhaust System Lengths 20.1 , 40.2 , 80.5 , 160.9"

You might want to look into Merge collectors - the spike in the middle keeps the velocity high -, if there are some cheap 2 tube ones on ebay
example of 4 tube one
http://www.burnsstainless.com/mergecollectorsmain.aspx

[tau9]

Originally Posted by Old Grey

I had to fudge some numbers, because the specs aren't on the web, but they should be close enough

I gave you a range, so pick one or interpolate what you want.

Peak 6800 rpm
Range 4800 to 7300 RPM
1st Segment 1.471" dia - Length 12.6" to 13.9"
2nd Segment 1.570" dia - Length 12.6" to 13.9"
Collector 2.270" to 2.520" Lengths 15.7"(best) or 7.8" or 31.4"
Best HP/TQ Total Exhaust System Lengths 15.7 , 31.4 , 62.7 , 125.5"

Peak 6500 rpm
Range 4500 to 7000 RPM
1st Segment 1.439" dia - Length 13.2" to 14.5"
2nd Segment 1.570" dia - Length 13.2" to 14.5"
Collector 2.214" to 2.464" Lengths 16.4"(best) or 8.2" or 32.8"
Best HP/TQ Total Exhaust System Lengths 16.4 , 32.8 , 65.6 , 131.3"

Peak 6200 rpm
Range 4200 to 6700 RPM
1st Segment 1.405" dia - Length 13.9" to 15.2"
2nd Segment 1.530" dia - Length 13.9" to 15.2"
Collector 2.156" to 2.406" Lengths 17.2"(best) or 8.6" or 34.4"
Best HP/TQ Total Exhaust System Lengths 17.2 , 34.4 , 68.8 , 137.6"

Peak 5900 rpm
Range 3900 to 6400 RPM
1st Segment 1.371" dia - Length 14.6" to 16"
2nd Segment 1.496" dia - Length 14.6" to 16"
Collector 2.098" to 2.348" Lengths 18.1"(best) or 9.0" or 36.1"
Best HP/TQ Total Exhaust System Lengths 18.1 , 36.1 , 72.3 , 144.6"

Peak 5600 rpm
Range 3600 to 6100 RPM
1st Segment 1.335" dia - Length 15.5" to 16.9"
2nd Segment 1.460" dia - Length 15.5" to 16.9"
Collector 2.037" to 2.287" Lengths 19"(best) or 9.5" or 38.1"
Best HP/TQ Total Exhaust System Lengths 19 , 38.1 , 76.2 , 152.3"

Peak 5300 rpm
Range 3300 to 5800 RPM
1st Segment 1.299" dia - Length 16.5" to 17.8"
2nd Segment 1.424" dia - Length 16.5" to 17.8"
Collector 1.975" to 2.225" Lengths 20.1"(best) or 10.1" or 40.2"
Best HP/TQ Total Exhaust System Lengths 20.1 , 40.2 , 80.5 , 160.9"

You might want to look into Merge collectors - the spike in the middle keeps the velocity high -, if there are some cheap 2 tube ones on ebay
example of 4 tube one
http://www.burnsstainless.com/mergecollectorsmain.aspx

First of all thank you!

The protege FAQ page says the stock engine has peak power @6800RPM.

If I choose the first exhaust manifold design with peak power @6800RPM it will also improve lower RPM power due to his 4-2-1 design (the stock is 4-1)?

If it improves max hp and lower end it should be fine for my purposes. Do you think it's a good idea or better go to a lower rpm peak power manifold?

Finally what you mean with this data?

Collector 2.270" to 2.520" Lengths 15.7"(best) or 7.8" or 31.4"
Best HP/TQ Total Exhaust System Lengths 15.7 , 31.4 , 62.7 , 125.5"

EDIT: This are the measures of the ebay manifold

PRIMARIES - 15/8" (41MM)

SECONDARIES - 13/4" (44MM)

OUTLET - 21/4" (57MM)