making a new exhaust.

[kerry 10]

im going to rebuild my exhaust but i dont know what to do in regards to the set up. does any one know what would be best for up to 250rwhp!, e.g mufflers and resonators, twin pipes or single?. i know what i have works but it sounds like crap and cackles like mad.

cheers kerry

[zl2cq 1]

im going to rebuild my exhaust but i dont know what to do in regards to the set up. does any one know what would be best for up to 250rwhp!, e.g mufflers and resonators, twin pipes or single?. i know what i have works but it sounds like crap and cackles like mad.

cheers kerry

Kerry contact Pete Brown (the Pipeman) at Papakura Mufflers , he does some big stuff out there including the key dragsters and some E30 series, and top 4x4 competition trucks.

My E36 sounds ok for a 4 cyl. bu tperformance and economy are tops ............. and to what ever your budget will take !

good luck

Paul

[kerry 10]

Kerry contact Pete Brown (the Pipeman) at Papakura Mufflers , he does some big stuff out there including the key dragsters and some E30 series, and top 4x4 competition trucks.

My E36 sounds ok for a 4 cyl. bu tperformance and economy are tops ............. and to what ever your budget will take !

good luck

Paul

thanks bud. will get i touch, next on the list

[j.ingledew 0]

Straight pipe

But really, in the end, the straighter your exhaust, the better your flow so the better it's going to be, it's just working to keep it under 92dB that is the hard part

[Michael. 2312]

, it's just working to keep it under 92dB that is the hard part

Not really provided you use suitable catalytic converters, resonators and mufflers. Albeit ones that are made properly - Not generic junk.

[kerry 10]

Straight pipe

But really, in the end, the straighter your exhaust, the better your flow so the better it's going to be, it's just working to keep it under 92dB that is the hard part

its already straight and db to be honest dont bother me i just need to change it to get rid of the cackle, eg run 2 two the rear or whatever i need to do, as long as i get a mod that improves it il be happy

[MLM 57]

According to my design guides of which i have a few. To suppport 250rwhp (so 280ish + flywheel?) a single 3 inch exhaust is needed which is huge for a street car. Conversly 2 x 2 1/8 inch exhaust (up to 150hp each) would work too. Im not 100% sure if the 2 x 2 1/8 is equal to a single pipe is true but could dig a bit deeper if you like.

As for eliminating crackle.. thats more of a muffler design thing and would require experimentation to achieve.

[kerry 10]

digging deeper would be great as i currently run 2 1/2 inch straight through with middle res and oval coby rear box. it works great and sounds great screaming but mid range changes kill my ears every time ..., if i run 2x2 1/8 pipes i need to find a suitable muff which tends to be difficult.

[MLM 57]

Havnt been able to confirm anything but if you look at what works in other situations like btcc cars. They use a twin pipe design with a x pipe linking the two pipes and support 300 odd hp Pipe size seems to influence sound so maybe a twin pipe design with resonators would eliminate the crackle or at least make it more managable. would weigh twice as much though.

There are literaly 1000s of muffler designs and principals out there. It might be a case of listening out for what sounds good or others recomendations.

[thorburn 120]

http://www.exhaustvideos.com/faq/how-to-ca...-pipe-diameter/

From this it seems the area of the pipe is the direct relation to how much hp it recommends.

My 328 has 2x 1.8inch (46mm)diameter pipes and is supposed to make 190hp (142kw). Really no comparison to what you are wanting to achieve. Either way the cross sectional area of the 2 pipes is: (pi x (1.8/2)^2) x2 =5.1 square inches (33cm^2)

Kerry's setup has an area of: (pi x (2.5/2)^2) = 4.9 square inches (32cm^2)

The e36 m3's had 2x 2inch (50mm)diameter pipes. According to wiki s50's make 282 and 316hp (210 and 236 kw). And area of: (pi x (2/2)^2) x2 =6.3 square inches (41cm^2)

This is just very rough as i'm too lazy to measure the internal diameter of everything. But I hope it at least shows that you should use s50 exhaust parts.

This should also make it easier to find a suitable muffler

or you could run 3 pipes...

edited to keep 3pedals happy

Edited March 26, 2011 by bbs

[thorburn 120]

The E36 M3 3.2 has two 63mm diameter pipes

Are you sure it's 63mm? i've got what I believe to be b32 headers that end at 2 inches or about 50mm. I've also got a milltek centre section for an m3 with the same dimensions. Edited March 26, 2011 by bbs

[sweetm3 180]

Hi guys

Attached is a sketch of my 97 3.2 M3 exhaust with some diameter measurements.

[kerry 10]

seems to me the logic bmw has with there exhaust is bloody good so if i keep with what they used on a m3 and info from here i will be in the right place . i might try running 2 63mm to the rear with a couple of long resonators in the centre and go for a twin in out muffler. see how that goes.

[hybrid 1039]

With your car being an e30, ditch the cats as around cert time e30's never had them so no point putting them on.

For the s50b32 for the best in torque go for 2inch thin walled stainless and carry it up to about mid way. Use a straight through center muffler (no s-bends or traps) then 2inch through to the back box muffler. Dont use a straight through back box muffler as it wont muffle the sound enough. Something nice a deep should be good, just remember that it needs to be able to muffle the lack of second center muffler or trap based center muffler.

If you're going to be running above a 264/256 cam set then going to 2.5 inch all the way will help top end flow at the expense of mid range torque.

Stock m3 BMW exhausts are tuned for extra 'blockages' of running catalytic converters. Hence the different sizes in pipe diameters.

I built my exhuast on advice given from gavin and what I wanted the car for and what hes seen on his dyno and tuning. Im running an s50 obviously which pushes more air naturally with the extra literage of the engine and flow of the larger valves. So you should land about right on 2inch with your setup kerry.

Just do me a favour and dont make it out of mild steel. Go thin walled stainless if you can shell the $$$ for it.

Eventually my plan to 3.4/.5 stroker my engine comes to fruition (a far way off) then ill be changing to 2.5inch.

[kerry 10]

With your car being an e30, ditch the cats as around cert time e30's never had them so no point putting them on.

For the s50b32 for the best in torque go for 2inch thin walled stainless and carry it up to about mid way. Use a straight through center muffler (no s-bends or traps) then 2inch through to the back box muffler. Dont use a straight through back box muffler as it wont muffle the sound enough. Something nice a deep should be good, just remember that it needs to be able to muffle the lack of second center muffler or trap based center muffler.

If you're going to be running above a 264/256 cam set then going to 2.5 inch all the way will help top end flow at the expense of mid range torque.

Stock m3 BMW exhausts are tuned for extra 'blockages' of running catalytic converters. Hence the different sizes in pipe diameters.

I built my exhuast on advice given from gavin and what I wanted the car for and what hes seen on his dyno and tuning. Im running an s50 obviously which pushes more air naturally with the extra literage of the engine and flow of the larger valves. So you should land about right on 2inch with your setup kerry.

Just do me a favour and dont make it out of mild steel. Go thin walled stainless if you can shell the $$$ for it.

Eventually my plan to 3.4/.5 stroker my engine comes to fruition (a far way off) then ill be changing to 2.5inch.

3.4/.5 stroke will be impressive il keep my eyes out for that thread.. i assume you mean a double 2 inch system?... as for cams ive decided im going back to double vanos, my tuner down here has had great results with variable cam timing engines and recommends i go with it.

[thorburn 120]

Good to hear the vanos will be back

[zenetti 0]

The torque delivery is determined primarily in the headers not in the mid and tail sections.

What DOES happen in the mid and tail sections is interference from changes in resistance along the pipe and that comes from cats / straight through, other muffler types changes in pipe diameter and sharp bends.

Reducing the pipe size gives a perception of increased torque because it masks the interference and reduces maximum power.

A properly designed system with the correctly graded resistance providing the minimum practical flow resistance whilst maintaining good velocity in the headers and consistent extraction will give more torque and more maximum power.

If the cats are too restrictive then they are not macthed to the flow - change them so they do

Straight through perforated type mufflers also add a restriction because the cause turbulence at the tube face which reduces the effective diameter.

Current exhaust theory works very much on well proven Transmission line principles to effectively eliminate reverse pressure waves (reflections).

and in laymans terms???

[MLM 57]

Restriction of any kind is bad. Get rid of it.

[sweetm3 180]

and in laymans terms???

I found this link when doing a quick google on 3pedals post

touchs on pressure waves

[hybrid 1039]

i assume you mean a double 2 inch system?... as for cams ive decided im going back to double vanos, my tuner down here has had great results with variable cam timing engines and recommends i go with it.

Yeah sorry dual 2 inch. Keeping it two pipes will let the engine keep its mid range torque curve instead flattening it out (true story ). For a road car / track car Vanos is still a really good system. You will only step out side of its adjustment range if your going for wild cams.

Variable cam timing is perfect for road/track day usage.

In the real world you will use your mid range torque most.

Would you believe there is a noticeble difference when when I put my straight through perferated center muffler on vs the straight through in the top end. Fabricator was suprised. Shows you how sensitive the 6's are when you mess with their systems.