Toyota Nation Forum banner

21 - 38 of 38 Posts

·
Registered
Joined
·
907 Posts
That makes sense, you did it by ear.

Another question about you distributor timing diagrams. Using the in line 4 as an example are the exhaust pulses technically 180 degrees out of phase, and it would take two complete 360 degree crank revolutions (720 degrees) to get all four exhaust pulses? So your diagram makes sense but is a little misleading, no?

The next question is pipe length to get the amount of offset to make the rumble. As long as the cylinders were paired like on a in line 4 line they are on a boxer 4, meaning cylinders that fire one after another have to have the primaries paired. So say a Toyota inline 4 with 1-3-4-2 firing order would need 1-3 paired and 4-2 paired. If the offset was to be adjusted from 90 degrees apart to 90-135-90-45 then wouldn't the secondary length of pair 4-2 have to be 1.5 times longer before the secondaries meet at the collector?
 

·
Registered
Joined
·
907 Posts
Why didn't they come up with that a long time ago, seem like a great idea. Especially since inline 4 cylinders are balanced great to begin with.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #24
I guess if someone really wanted to, they could cut the crank, cam, and figured out a way to redo the timing, someone could probably make a crossplane inline 4, but from what I could ascertain, http://forums.tdiclub.com/showthread.php?t=275665 Vibrations on a long shaft four cylinder design would vibrate itself to death, besides, the point of the crossplane is to elimate wheel slipages, by giving the tires a break with a small delay, as pointed out in the thread, I dont think a toyota has traction issues, and there is no real benefit in using a crossplane as opposed to a flat plane crank. You do get that v8 sound though!

@Nogard, your numbers are the same as mine, with the exception that your numbers are multiplied by two, we're speaking the same language, except you're accounting for the four strokes (i e two rotations of a crankshaft) where as I'm just measuring the angles of a distributor.

in terms of pipe length, one thing to take into consideration with regards to subaru UEL headers, is the primaries are relatively long, they appear to be half the length of the secondaries. with that said, if someone were to simply remove the excessively length primary pipes, and simply have the secondary long pipes, relay directly to the primaries it would have a burble similar to that of a v8.
I Can't find a definitive picture of DNA motoring unequal length headers, but from what I can hear, it sounds extremely close to the sound that I'm after, maybe not exactly, but definitely warm.
Fast forward the video to 1:10.
http://www.youtube.com/watch?v=fEcjIcp2BgQ

 

·
Registered
Joined
·
907 Posts
On the numbers of the exhaust pulses I agree with you and understand what you are saying.

Header terms, I want to make sure we are talking about the same thing. I always thought the primaries were the pipe that comes off the flange attached to the head, and the secondaries are next after that. What you are saying for length sounds backward. Don't you mean that the primaries are extremely short, and the secondaries are long? I agree for the in line 4 the primaries could be longer to better fit the layout and staggered for "rumble sound" before the all enter a collect like a shorty header, or go through a secondary like a 4-2-1 header.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #26
It doesn't make any difference whether Cylinder's 1 & 2 are longer than 3 & 4 or vice versa, as long as Cylinder 1 is paired with 2 and cylinder 3 paired with 4. However It cannot work if cylinder 1 is paired 4 or if 2 is paired with 3. And in terms of pipe length needed, I'm pretty sure if the long pipes simple go around the engine to join with the shorter pipes on the other-side, I'll get the sound I'm after.
 

·
Registered
Joined
·
907 Posts
I agree with the cylinder pairing 1/2 and 3/4 to get the sound. I also drew a diagram to see how it would work with crank/piston timing. Basically you were illustrating the distributor timing/camshaft timing which rotates half the speed of the crank. What you originally posted makes sense to me now. So what you have with one revolution of the cam, 90-90-90-90 would be two revolutions of the crank/pistons, 180-180-180-180. So cam 90-45-90-135 is the same as crank 180-90-180-270.

So if the offset of the exhaust pulses needs to be 50% more, would the pipe length need to be 50% longer. Say cylinders 1 & 2 had a 12" primary, then couldn't 3 & 4 have a 18" primary. 4, 90 degree bends back to back would fit in the same 12" length.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #28
I don't ratios play a role, (atleast not that im aware of) but I do think pipes have to be slightly longer than what you would typically see on a Subaru. But I guess if on a subaru (granted that the primaries represent the short pipes, and the secondairies; the long pipes) if the primaries are 8" and the secondaries are 40", then removing the 8" from the primaries would accelerate the sound pulse and subsequently delay the secondaries. But in terms of pipe length need, my guess would be, 50 inches in length offset by the 2" - 6" primaries, but I can't say definitively. But in the near future, once we take the car out of storage, Im going to head over to Canadian tire and buy some piping, I also plan on grabbing the existing exhaust manifold, spliting it two, and reversing their locations so (>>I<<) (I<< >>I) I'll simply buy a large diameter pipe and and snake it around the engine parts, I reckon that there's going to be some up and down bends, so that will add length and by the time it goes around the engine, it should measure somewhere within the 30 - 50 inch range. Thinking about it now, I can't wait to see the expression on people's faces when they hear a 302 mustang burbling and all they see is a little ratted-out golf.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #30 (Edited)
I've been searching the web and I happened to stumble upon this. I think this is well within the bracket of a 4 cylinder that sounds like an 8.
 

·
Registered
Joined
·
907 Posts
That's a great idea to use flexible exhaust pipe for you test. You are doing this on a VW? I thought it was a Toyota for some reason. I would like to do this to a 2nd generation Camry. It will be more of a challenge, the cast exhaust manifold is short and the catalytic converter is directly attached to it.

I know it can be done, it is great you are doing it. For me I really want to know the math/science behind the pulse delays verses difference in pipe length between the two paired cylinder sets.
 

·
Registered
Joined
·
907 Posts
I've been searching the web and I happened to stumble upon this. I think this is well within the bracket of a 4 cylinder that sounds like an 8.
First clip was the best sounding, although that was neat how the guy in the second clip added a 180 section of pipe to his stock exhaust manifold to offset the exhaust pulses to get that rumble. I have a 2000 Legacy L 2.5L with a UEL header, stock cats, and 3" glass pack for muffler. It sounds a lot like the first video clip you posted :thumbsup:.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #34
Hey everyone, its been almost a year now and with disapointment I have to say that I never had a chance to try out my exhaust concept, money, time and a lack of a vehicle are all factors that contributed to this, on the plus side I worked as a technicien at a bike shop, I mostly assembled new Devinci, specialized and rocky mountain bikes, along with repairs it was a great experience. When I wasn't working (or drunk) I thought about cars, I also thought about my exhaust and improvements. My original header was a wrap-around engine design, however this design would have sure been prone to engine failure with the exhaust gasses heating the entire block, combine that with unequal exhaust pressures and you get the drift. This design however, will cost less to make and will maintain if not improve performance. The way it works is by having a true dual exhaust system, but rather than have a 50inch wrap around manifold, there will simply be a 50 inch H pipe, which will do the same job as the header (delay the sound pulse) however it will flow better, and you'll be able to hear it on both sides of the vehicle, giving it that true v8 sound, or at least a subaru'ish/air cooled volks sound, or maybe even somewhere in-between.
 

·
Registered
Joined
·
1 Posts
Love the idea, i've got an MR2 and always wanted a v8 sound, in fact managed to squeeze an audi 4.2 v8 engine in the back once with a stupid amount of modifications, sadly didn't get the time to get it finished though!

Anyway got lots of exhaust pipe spare so going to try out different angles and see what sound I can produce from a single header on my 2L MR2. If I get some good results i'll post on here!
 

·
Registered
Joined
·
2 Posts
The next question is pipe length to get the amount of offset to make the rumble. As long as the cylinders were paired like on a in line 4 line they are on a boxer 4, meaning cylinders that fire one after another have to have the primaries paired. So say a Toyota inline 4 with 1-3-4-2 firing order would need 1-3 paired and 4-2 paired. If the offset was to be adjusted from 90 degrees apart to 90-135-90-45 then wouldn't the secondary length of pair 4-2 have to be 1.5 times longer before the secondaries meet at the collector?
[/QUOTE]

Hi, I am going to be making an UEL header for my Mk1 Toyota Mr2. Which is a 4AGE engine with a firing order of 1-3-4-2.

So would i pair 1&3 together and 4&2 like you have stated above, and then make 4&2 longer than 1&3 and loop around the other runner like in this design?

I think this design is nice and simple, it is proven on a Honda D16 engine. I have seen videos on youtube, it really does sound good.

My only concern is i believe the firing order for the Honda D16 is 1-2-3-4?, so 1&2 together and 3&4 together. Would that mean i would have to do the same or is it just that i have to pair the cylinders that fire straight after the other??? So confused, please help
 

Attachments

·
Token Aussie
Joined
·
1,752 Posts
My only concern is i believe the firing order for the Honda D16 is 1-2-3-4?, so 1&2 together and 3&4 together. Would that mean i would have to do the same or is it just that i have to pair the cylinders that fire straight after the other??? So confused, please help
There is no way that the D16 has a 1-2-3-4 firing order, the imbalances and vibrations would be terrible.

I laugh at the continued use of firing angles throughout this thread that add up to 360 degrees (ie 90-90-90-90), when even a person who has a passing interest in how 4-stroke engines work should know that firing angles add up to 720 degrees (the crank has to go through two rotations for all cylinders to fire, your average 1-3-4-2 4-cylinder engine has a flat-plane crank with 180 degrees between each cylinder firing).

Also, the post you replied to is ~3 years old, and the majority of this thread is ~5 years old.
 

·
Registered
Joined
·
2 Posts
My bad, i saw a diagram of the d16 engine with the cylinders numbered 1234, however the firing order is 1342. My question is, do i pair cylinders 1 and 3 together and make them the shorter length combined runner and pair cylinders 4 and 2 together and make them the longer looped combined runner?.. to get the unequal length header right. If you can help me with this many thanks
 
21 - 38 of 38 Posts
Top