Toysrme

So here's my answer to why on a stock 3vz-e, an AFM upgrade is useless. *On the stock/near stock engine*

1) It doesn't help a 2.5L 2vz-fe which makes more power, it won't help a near-stock 3vz-e

2) It does nothing to stock miata engine that consumes almost as much air @ high rpm as a 3vz-e. It DOES help a lot when they have gone FI

3) The math itself says it won't really help very much.

***So here's the math.***

Because of a lack of 3vz-e dyno's, I've never personally even seen one; I will instead use the power curves of a 5vz-fe because it's the only other low rpm Toyota v6 to compare to. Note I said the power CURVE. Not the dyno numbers itself. The curve of 5vz-fe dynos fairly closely matches the published peak figures for a 3vz-e anyways. This will ensure that I OVER estimate 3vz-e numbers. Simply put, the day a 3vz-e power curve is better than an FE head & cams - hell has frozen over.

If someone will provide a 3vz-e dyno, I will be happy to provide the real numbers , but as I just mentioned... It will make the math even more biased that the stock AFM is fine.

Warning: Generalization - SOHC peak volumetric efficiency will be calculated @ 80% peak.



Data:
Bore: 3.44"
Stroke: 3.22
6 cylinders
Ambient air temp: 70*F

@ 3500rpm
Volumetric Efficiency = 80%
145CFM
@ 4000rpm
Volumetric Efficiency = 78%
162CFM
@ 4500rpm
Volumetric Efficiency = 75%
163CFM
@ 5000rpm
Volumetric Efficiency = 66%
171CFM
@ 5500rpm
Volumetric Efficiency = 53%
151CFM

Small Denso AFM housing has been rated 165CFM @ 0.74in.Hg
Large Denso AFM housing has been rated 200CFM @ 0.74in.Hg

As demonstrated, peak flow on a stock engine is @ 5000rpm - 171CFM, while the AFM will measure 165CFM. So now the money question... What *WOULD* happen if you swapped one. Here ya go:
@ 5000rpm you would get a power bump from 126bhp = 165CFM, to 131bhp = 171CFM.
Now remember. The 5vz-fe powercurve is going to fall off less than the 3vz-e power curve. Most likely, it nose dives so fast, it most likely would peak out right around 165CFM - we all can honestly say it surly won't make 171CFM.



Sooooooo. I've said it a hundred times & I can pretty well prove it now. I can prove it 100% if someone provides me a dyno.

The 3vz-e's small denso AFM is NOT TOO SMALL for a stock/near stock engine.!!!





So, you're bummed that an AFM upgrade isn't really gonna do much. No fear. I've said something else multiple times too. We all know stock Toyota tuning sucks.

AFM with the silicon holding the plastic top cut.


Close up of the AFM spring & the cog that holds tension on it.


MARK THE STARTING POSITION.

Tighter spring leans, looser spring richens. ***Most stock & near stock Toyota engines don't need extra fuel, if anyting, lean them slightly.***



Expect a slightly better throttle response, and a few more horsepower @ high rpm. Mid rpm will also pick up a little when the engine is under load. Don't expect a large gas-mileage increase, but several 3s-fe M/T owners have reported less lugging in gear & increased mileage. IDK of any A/T owner of any 3s-fe 2vz-fe 3vz-fe owner that got more mileage.

3vz-e's have a distributor also... If you're not on the brink of detonation, add a few degrees of base timing advance. It won't give any appreciable peak power, but it will improve throttle response, and shift the entire powerband down a couple hundred rpm if you add enough.





There you go. There's the good & the bad. The good news - probably 90% of you that want a new AFM, don't need to waste time & money on one. You can also make more power with what you have already.

Flamedx4

The fuel delivery signal is much more important than the ability to flow more volume. Always has been always will be.
A good analogy (for us old guys) is - put a Holley 850 on a Pinto. Will it make more power? No, and in fact it will most likely run much much worse.
Unless of course you put a Turbonator on it - THEN it will make more power and get more economy....

Toysrme

Eh, that's not the same exact thing, but yes, you're right & the idea is right.
Big carb on an engine that can't use that much fuel doesn't really work.
Just like a big hole on small engine that doesn't immediately have a use for any more doesn't really work.


The arguement has always been that the AFM housing/hole is so small, that it can't possibly flow what the engine wants to suck through it, not that it can't deliver enough fuel. If you maxed the signal out, it'd try to deliver 200bhp+ worth of fuel - that's no problem.





It's like... Want a reason to go with a bigger afm, or a MAF/AP conversion where you actually would have power to gain? Hurry weasy's 3vz-e cams up, or go port & polish your heads w' a good valve job. That'll increase how much it's taking in & the cams will send the higher rpm VE out the roof. Or just go FI. Either way, then you would actually have a FEW horsepower to gain by doing some kind of swap & it would be worth the investment!

Flamedx4

or you could just put one of those $59 eBay electric turbochargers on there...

myyota

I was doing some searching on AFM swaps when i came across this thread. Now i thought the idea of swapping a supra AFM onto a 22RE was to improve air flow and possibly gain a little more power and maybe a little better gas mileage, but after reading this thread were there talking about leaning out the factory AFM will gain some power because the our engines are tunned to run rich from the factory, now i know there talking about a 3vz-e engine here, but would this apply to a 22RE as well ?. I still plan on doing an AFM swap on my 86 22RE, but after reading this thread it just got me to thinking, you can possibly lean out your stock AFM and maybe gain some power and maybe risk burning a valve or piston ?, or swap in the larger AFM, and in my opinion this would be safer. So im looking for thoughts and opinions on this.

ozziesironmanoffroad

maybe swap in the new afm and fine tune that one.

scuba

Wrong section much ?

seanmearse

So, lean out the fuel what, one or two teeth on the wheel? right?

Fink

Even though this thread is several years old, I moved it to the General section.

Fink

seanmearse

Hope its okay to keep posting in here.

So, how many teeth on that cog constitutes "a little" when leaning it out.

881stGenRunner

why would you care if it was in the wrong section or not? Its an old tech thread, do you have to analyze every little detail about a thread just to find someone to bash on? get out of here man, im tired of your bull in all these threads, and im sure a lot of people are too.

seanmearse

I know you arent talking to me.

881stGenRunner

no i am not, sorry bout that. i was talking to scuba

Dan.3

swapped89

I've been waiting for a good time to use one of those. Just as good seeing it is properly used.