Thread 28696040

How good are they? They look cool and seem like a simple physical modification for most cars compared to a turbo or super package. What's stopping someone bolting one onto something like a micra or ford ka?

>>28696040 (OP)
Balancing 8 single carbs is a nightmare.
Any misadjustment or slop in linkage can easily throw a cylinder 25% out of whack.

>>28696062
>Balancing 8 single carbs is a nightmare.
they're only throttle bodies.
but balancing 8 carbs isn't actually hard after finding ballpark for the jetting,
truth is cylinder to cylinder distribution is rarely perfect even on fuel injection cars, often some are lean.
If you really give a shit you probably need demolition headers with o2 bungs per runner to tune them correctly.
itbs are just fuckin air blades and presumably injectors in them or on the intake

>>28696062
Go fuel injection

most overrated car mod, total meme
most half decent engines nowadays will have a properly tuned intake manifold which is barely giving up any power

>>28696070
>>28696072
Doesn't matter if carb or TB.
Youre still talking about 8 butterfly valves.

This is a common nightmare in the motorcycle world where 2/4/6 carb/TBs are standard.
Factory linkage is great for ~50k miles. After that you start to get phase issues.
Trying to balance 2 usually isnt bad. 4 can be frustrating. 6 requires skill.
Aftermarket setups are generally horrible.

>>28696040 (OP)
>How good are they
Not really that good. Balancing them is a pain. Getting an air filter setup is a pain. And it's generally really expensive.

If you have a single carb v8 with a big camshaft then going ITB can gain you some mid range power because it mitigates the problem of exhaust reversion, but on a Ford Ka you aren't going to gain any horsepower.

>but muh throttle response
That is because you have multiple butterflys opening at once. Basically the physical version of having a more aggressive throttle map. Not really a good thing.

>>28696040 (OP)
absolutely worst bang for buck mod

>>28696040 (OP)
>What's stopping someone bolting one onto something like a micra or ford ka?
They cost more than the entire car and gains of diminishing returns

>>28696088
>put pedal at wot
>adjust to make sure they all are WOT but also all return to 0% input
is this really that hard

>>28696040 (OP)
https://www.youtube.com/watch?v=zonvcNFbOgw
Can be done, just requires a bit of ingenuity and CAD know-how.
You most likely won't really get any extra power out of it, but the response will be quicker and it'll sound cool.

>>28696040 (OP)
>How good are they?
Dey a'ight.
>They look cool and seem like a simple physical modification for most cars compared to a turbo or super package
Plug 'n play ITB kits are easier to install than plug 'n play forced induction kits, but it's the reverse for bespoke setups.
>What's stopping someone bolting one onto something like a micra or ford ka?
Budget, usually. ITB's are usually ludicrously expensive and offer an extremely poor $ to hp ratio, hence why they very rarely show up on anything that isn't pushing the limits of natural aspiration.

>>28696040 (OP)
>How good are they?
They're fucking annoying

>>28696062
>>28696088
>>28696249
>>28696441
Fun fact: The Muster koach has 10 (TEN) individul carburetors. Imagine balancing that

>>28696088
I LOVE MY 4 CARB BIKE :)
(I hate my 4 carb bike)

>>28696249
No the response comes from the throttle bodies being closer to the intake valve - so you don't have to fill the whole manifold up with atmo pressure before it gets to the engine, you only have to fill the intake port up with atmo pressure.

You guys know you can make all of your lives easier and still retain all the benefits of a purely mechanical system.

>>28696040 (OP)
Extremely cool. Not worth it on a street car, though. At least not one made for DD'ing.

>>28696760
Linkages look cooler tho

Work best on 4cyl engines there is less to sync up and get running right
Even better for rotaries where only 1 is needed per rotor

Ok but what are the actual torque curve benefits of ITBs?

>>28697041
Lot of cars have them stock, just in a box. inline M3s Skylines etc just top of my mind.
A plenum also helps with heat soak and fine tuning even more.

I have a set of ITBs on my civic in a box, uninstalled since I just paid out the ass to tune it I'm kinda not in a rush to do all that nonsense again.

>>28697266
That's the fun part, just swap trumpet lengths for your needs.

>>28698046
>just swap trumpet lengths
Wait, really?

>>28698419
makes sense - it's how variable length intake manifolds keep long runners for low end torque, then open up the shortcut path for high end hp

>>28696040 (OP)
me and my brother fabbed up an intake manifold and bolted 750 gxr carbs on his suzuki samurai. after weeks of tuning and jet'ing it ran like a raped ape the sound was just pure sex. it already had a cam and headers and we tried that on the stock carb it was meh it really needed this setup to wake it up.
he eventually ditched them and got a weber 32/36 he just got tired of constantly tuning and balansing carbs. not much loss in performance and no need to fiddle with it daily.

>>28696040 (OP)
Meme mod, good for noise

>>28698469
sounds like a carb cheater would've been perfect for him

>>28698469
No imagine how insignificant the difference would've been if the stock Suzuki engine had a tuned length EFI intake manifold instead of this shitty downdraught monstrosity.

>>28696285
Yeah, tiny differences in blade clearance slightly off throttle (where you spend the majority of the time driving) can create big differences in airflow.

>>28701054
Now* imagine
whoops

>>28696040 (OP)
Good for noise
Good for throttle response
Not worth for power

>>28696084
You don't run ITBs with a plenum inlet like that.

You get nothing from ITBs that you can't get from a well tuned intake mani with variable chambers.

>>28701216
Stock engines do
Sure you can pay out the arse for some big gay piece of mattress foam with pipercross written on it but you won't actually make any more power

>>28698419
>>28698425
In an attempt to explain this, when the valve opens this creates a low-pressure wave that travels through the intake 'trumpet', because the air is being sucked in. Once that wave reaches the open end of the trumpet, air from the surrounding starts rushing it. This leads to the wave being reflected as high-pressure wave. When this high-pressure wave reaches the valve, it forces more air in the engine than should be at atmospheric pressure. But only briefly. If the valve closes at the right time, it'll trap the extra air. The waves always travel at the speed of sound, so their run-time is decided by how far they have to travel (i.e. how long is that trumpet). A longer runner will cause the wave to take longer, so the valve needs to be open for more ms than for a shorter runner, and the extra air is thus trapped best at lower rpm. For very short runners, the wave is quick and the valve has to close shortly or it'll all leak out, you'll thus have the best air-mass at high rpm.

>>28702338
You've got it a bit backwards there buddy, I'm sure the valve opening creates a wave but it's the valve CLOSING which creates the strong high pressure wave - all the air traveling through your intake port into the cylinder has MOMENTUM and when the valve suddenly closes in its face it gets stacked up like a trainwreck into a high pressure zone at the valve which bounces back out the runner.
A nice manifold will have a flat wall opposing the intake trumpet which reflects the wave back, but open atmosphere (for open trumpets) also has a reflective characteristic as the high pressure wave blasting out of the trumpet will be follow by a lower pressure void which the atmospheric pressure rushes in to fill.

But yes the goal is to time that reflective wave so that it arrives at the valve just as it opens again for the next intake cycle.

>>28702338
yea what the other guy said - it's the closing of the valve that creates high pressure, intake manifolds are designed to reflect this high pressure wave back at a certain rpm (rpms?) as the valve opens to give a mild supercharging effect.

They aren't easy unless you're buying a ready to go drop in kit which is a gorillian dollars

Guess I remembered that slightly wrong...
It's been ten years since that class after all

>>28697863
>Lot of cars have them stock
I wouldn't say that a "lot" of a cars have them. ITB is extremely rare. BMW used to be the leader in this, but now they've shied away from it. The Nissan used to do it on the R34, but didn't do it on the R35. Ferrari only did it on the F355.

>>28705477
I mean.... if we include all the cars which have independent throttle body carbs - yeah there's a LOT.

>>28696040 (OP)
Did this on my daily driver, i used the ITBs from a 4AGE Black Top.
I don't think i gained any horses, but the sound is really worth it.
Did learn a lot tho, great decision.

>>28706019
>went through all the effort to fit and tune ITBs
>"I don't think I gained any horses"

Average ITB experience

>>28706712
Yeah, as everyone's said already, you do it for the responsiveness, the noise, and the cool points.

>>28705996
>independent throttle body carbs
You mean individual? Never heard of independent TBs unless you dual TBs or multi-barrel carbs or something.

What cars have these?

>>28706819
yeah I did a wordo

>>28706819
On that topic, some BMW bikes have a semi-independent setup. Four throttle bodies, two separate motors.
Apparently it has to do with how they handle traction control.