Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[razor1uk]

  I suggest finding a German version of the legandry 'Tuning for Speed' by Phil Irving, and Congo is correct.
 
  Intakes and Exhaust ideally need to be harmonically tuned/balanced each to the respective Inlet & Exhaust Valve timings at the desired rpm like tuning a trumpet or trombone.

  This is why silencer/muffler 'boxes' have many compartments; to trick the exhaust into acting like a longer 'straighter' pipe and (normally on most 600cc+ bikes) an adjustable valve in the exhaust to alter flow routing and/or pressure of the harmonic reverse waves to further trick the exhaust into thinking its high rpm designed pipe is a low rpm pipe at low powers.

  You can also use 2 stroke inspired Kaaden style pipes on a 4 stroke engine, although they involve much more (advanced) maths as your engine power pulses/cycles & exhaust temperature are much different between 2 & 4 stroke motors.
  They'll need a swept length up to 4 times the equivelent 2 stroke pipe length IIRC - for a pipe of with a similar exhaust to valve port size per cylinder. Naturaly this is also dependant upon the harmonic timings you select. The internal pipe smoothness; of taper changes and internal welded surfaces finish is more critical in Kaaden/Megaphonic pipes.

Use cereal boxes cardboard to arrange the parts you design for routing purposes - much cheaper than have to 'draft' the pipes from metal first.

[dinosaurJR]

To be honest, all of this advanced tuning (and it is advanced tuning - normally you just buy an uprated manifold off the shelf) is going to require matched inlet and exhaust manifolds. You have to match the length of the inlet to the power pulse timing of the engine and this can only be done by adjusting the shape of the manifold itself. Off the top of my head I can't think of anyone who makes these off the shelf which means bespoke design and manufacture. Don't get me wrong - this is fascinating and I for one would like to see and hear this when it is done - but it seems like a lot of work and expense. And probably too much hassle for the engine in question...

I would really suggest the following;

1. Give the engine a good service (you dont mention how many Km are on the engine or if it is serviced regularly - the very best and simplest tuning is regular servicing). Adjust the valve clearances (if the valve train is mechanical) and check the valve train for wear and tear (you have an OverHeadValve (OHV) engine, so the camshaft lives in the block and the top end is timed with a chain. Change the oil and filter. Change out the spark plugs. Check the coolant system - including the pump - for leaks. Change the air filter. If it has a distributor, check the rotor arm and distributor cap for wear, check the ignition leads also and replace all parts that are worn beyond adjustment / repair. This will release a few more bhp as the engine will be running at closer to its optimal state of tune.

Next, if it were me looking for some extra power, I would leave the exhaust manifolds where they are and have custom downpipes and straight through exhausts made. I would also throw away the fuel injection system and replace it with carburetors. You get a real nice exhaust and induction sound, believe me

After that it's a case of how far do you go? Lightened and balanced crank? Lightened and balanced flywheel? re profiled cams? Gas flowed heads? How about a light pressure turbo? Or how about the whole nine yards and replace it with a turbo charged EJ boxer from a WRX? I know a couple of guys that have done it with the VW Beetle... 200+bhp easy... 2wd conversions are not too difficult... Ive seen it done to a Mk2 16v Golf GTI too...

It really is up to you.

[HansHansen]

thanks for you advice guys 

unfortunately i did not find a german translation of "Tuning for Speed", maybe i can find a similar book in german about engine tuning.

but now the big question is: how can i see or hear if intake and exhaust are timed well? does the engine sound different?

i´d really love to tune the engine, but some things really hold me back:

1.I never made those things before, sure i can tell all the names of the different parts of the engine and what they do, however i do not have practical experience, so i need a guy who made all those things before.

2.Money most of the budget is needed for the cabin we mounted on the back, and at the moment we need every cent

3.Time: This project should be finished until spring. enough time for engine tuning itself, but the cabin is maybe halfway finished, and we have this project going for maybe one year. we still need the walls, the windows, the floor, a desk, telephone installation, radio, painting.... 


Sure it would be great to mount a subaru engine, however it really doesnt make sense at all  for let say 50km/h it will drive for 500m, some 60hp engine is enough, but it would be great to tune it a bit 

[dinosaurJR]

thanks for you advice guys 

You are very welcome - I understand that modifying VW busses is very popular in Germany - some of them look amazing!

but now the big question is: how can i see or hear if intake and exhaust are timed well? does the engine sound different?

The only real way is to put the car on a rolling road and check the power output / fiddle around with the spark, fueling and valve timing / re test on the rolling road. rinse and repeat... This is actually one thing I forgot to mention - the valve timing is fixed on your engine (the cam pulleys is not slotted to allow for fine tuning of the valve timing) - to get the best gains from such a manifold swap, you really need to fine tune the valve timing, the ignition timing (simple if it is a distributor, more difficult if is it electronic ignition...) and the fuel mixture (again, on carbs an easy adjustment, more difficult on an electronic injection vehicle...

i´d really love to tune the engine, but some things really hold me back:

1.I never made those things before, sure i can tell all the names of the different parts of the engine and what they do, however i do not have practical experience, so i need a guy who made all those things before.

2.Money most of the budget is needed for the cabin we mounted on the back, and at the moment we need every cent

3.Time: This project should be finished until spring. enough time for engine tuning itself, but the cabin is maybe halfway finished, and we have this project going for maybe one year. we still need the walls, the windows, the floor, a desk, telephone installation, radio, painting.... 

To reply;

1 - The best way to learn is to buy the workshop manual for your vehicle and read it. In the UK we have the Haynes manuals (do you have something similar in Germany?) and they give an in depth description of practically all parts, repairs and replacement jobs on your vehicle. Then it is just a case of getting your hands dirty - using the Manual as a guide. But don't take on any jobs you think are out of your league - it is easy to reduce a working motor to a pile of scrap if you do not know what you are doing...

2 - This is a bugger... However all is not lost - give the engine a good service (this should cost you for a set of spark plugs, an oil filter an air filter and 3 or 4 litres of oil (make sure you get the right parts and oil grade - the service manual should tell you, or dismount the relevant parts and take them with you to the shop.) Having the engine in tip top condition will always make it run better / sound smoother and more powerful - more reliable too. Check the ignition parts like the distributor cap, rotor are and ignition leads for cracks and wear - replace if anything looks slightly dodgy. Maybe if there is an in line fuel filter in the engine bay change that too (a screwdriver and about two minutes work) as a clogged filter can starve the engine of fuel... but if it looks clean (it is a transparent bowl with a small gauze filter element in it) just let it be...

3 - From what you are saying it seems that this bus is going to be heavily styled, look good. but not driven very far. To be honest with you I would just keep the engine well maintained and mount a loud exhaust. Find a universal fit back box (rear silencer) - it should not be too difficult to fit, you can do it yourself, saving time and money and it will sound a lot better (and look a lot better too if you choose a 4 or 5 inch tail pipe ) - especially if you remove all of the intermediate boxes from the exhaust and replace them with normal pipe (you can buy straight exhaust pipe from the same places as the universal back box.)

Sure it would be great to mount a subaru engine, however it really doesnt make sense at all  for let say 50km/h it will drive for 500m, some 60hp engine is enough, but it would be great to tune it a bit 

Yeah - this is more complex and would involve a fair bit of electronic work too... An yo would need to find a donor car (like a crashed WRX with the engine in good order...)

Good luck!!