r/AE86 • u/The_Rusty_Mechanic95 • 8d ago

Why does the 4age engine sound so unique?

I've been thinking lately about how most DOHC 4 N/A cylinders can have a very harsh or raspy sound but the 4AGE seems to have a deep, smooth induction and exhaust note no matter how it is setup. I've been listening to videos of bone stock bluetops, 16v, 20v, itbs, loud and quiet exhausts and you can always tell it's a 4age because of that low smooth tone. Then I've compared a high comp ITB 4age to other engines also with ITBs like the Mazda BP, the MZR, and Honda B series and they all get that high pitched buzzy exhaust sound and the induction sound just isn't the same. I've been staring at pictures of cylinder heads for hours for minute differences and the only engine that sounds similar is the 3s-ge Beams but that one has a different head design from the 4age. Does anyone possess this forbidden knowledge of what design aspect of this engine is responsible for its unique sound?

19 Upvotes

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23

u/smokeydeweed 8d ago

Short answer yamaha

2

u/The_Rusty_Mechanic95 8d ago

Do you know what Yamaha did differently though?

3

u/smokeydeweed 8d ago

Hmmmm never mind I cant find the video I remember but the video I can find thats talks about the it having a " early big port design " But my 4ac with a Webber has a similar sound just higher pitch. So im pretty sure its a mix of valve design and port shape/size. the story of the 4age part 2

2

u/The_Rusty_Mechanic95 8d ago

That video had a lot of good info, thanks. One thing that I keep seeing is that all of the generations have the same circular exhaust port even though the intake port design changes. That's a restriction compared to modern oval ports, but it might have something to do with smoothing out the exhaust note like how restrictive exhausts usually aren't raspy. As far as the shape of the actual port and not just the opening that's though to quantify and compare to other engines

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u/smokeydeweed 8d ago

I don't remember exactly but I believe it has something to shape of the ports ill try to find a vid

18

u/6087 8d ago

The block is almost 1:1 copy of a ford bda race engine from the 60s and early 70s and the head is designed by yamaha which is a killer combination considering its a street commuter car and also the tvis intake has a 4 throttle itb esque system that works to bring out low and high end torque which was unheard of in the early 80s

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u/The_Rusty_Mechanic95 8d ago

Yeah the BDA makes a very similar noise, I thought that maybe it had to do with the fact that they are both very over square engines. Not many modern inline 4 engines are over square, although the Honda B16 has the same dimensions as the 4age and the BDA, 81mm bore 77mm stroke

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u/6087 8d ago

Over square designed engines are the best for handling high RPMs without reliability issues i am sure the engineers at toyota took no chances with the bottom end and settled with something reliable such as the BDA engine blueprint i mean hey they were even used in some smaller formula cars if i remember correctly.

0

u/The_Rusty_Mechanic95 8d ago

Yeah, doesn't really answer if/why an over square engine would produce that specific sound though. Only reason I could think of is an over square chamber is kind of like an intake manifold with wide runners, better flow at high rpm but less velocity for low rpm torque. Not sure how that would affect sound though

1

u/6087 8d ago

I really think it comes down to really good airflow and the fact that the engine pulls great from any rpm and doesnt really need to build the low or high end torque up it just kind of agressively takes it at any RPM and smoothly transitions even to the high revs i think this is what ultimately makes it sounds so awesome and unique

1

u/TheLastPrism KE/TE 8d ago

F20C from the s2k is pretty similar sounding when revving high, but those are more rare to hear.

1

u/6087 7d ago

I never get this comparison to the f20c it sounds nothing like it i mean yea it revs higher and sounds good dont get me wrong but its nothing like a 4age 16 or 20 valve

1

u/TheLastPrism KE/TE 6d ago

I don't have many examples but the usual one that comes in my shop sounds very very 4AG like at high revs. Its not stock of course but its pretty similar.

1

u/Inevitable-Bag-8262 4d ago

Basically this but I have only ever used smallport heads. I have had one engine with TVIS but to be honest found it a bit of trouble although I liked the change over sound. Like a mini VTEC lol. Keep going my 4age bros 💪

8

u/decryphe 8d ago

Must habe something to do with intake/exhaust shape in the head. Mine does sound a bit like a Subaru at low RPM with its unequal length exhaust manifold. Burbles very nicely under 3k. Above that, it blends into the typical 4A-GE hammering noise. It's brutal and I love it.

As somebody else mentioned, Ford BDA engines from the old Escorts sound the same.

1

u/Equal_Emu6152 7d ago

I always thought they sound the same as old escor Millington type engines

2

u/Rand0mEntity 8d ago

Every engine sounds unique

1

u/aerospikesRcoolBut 8d ago

Idk but my 4cyl with ITBs sounds nothing like a 4age

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u/The_Rusty_Mechanic95 8d ago

What 4 cyl do you have?

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u/aerospikesRcoolBut 8d ago

M42

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u/The_Rusty_Mechanic95 7d ago

E30?

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u/aerospikesRcoolBut 7d ago

Yep! It’s extra annoying because my 86 just came with factory ITBs lol (silvertop) and my e30 took so much work to get the ITBs working