blow thru afm

[MWP]

Wont work.
The air wont be metered correctly as itll be compressed as it passes the flap.
The engine will run lean & detonate to death very quickly.
... on the sock ECU anyway.

[Jorrs]

pfft what a noob, have you done it mate?

I big peformance shop over here does it all the time on 4ages etc and was recomended to do it, frees up inlet and works the same.
Dont comment if you have not tried it.

is there anyway you can provide us with plausible results ?

[slipway NZ]

std 1ggte ecu

[slipway NZ]

so i am i noob? just causeyou have 10'000 posts on here dosnt mean you know anything...

[Mos]

hey boe, Blow through works a treat, was piss of piss to set up,
fuel cut went from 13psi to 20psi.

Dynod at 202kw atw std ecu fuel pump etc, was running 10.9afr

Pfft facty ECU ftw

Can you please comment on how the AFM is metering properly if the fuel cut went from 13psi to 20psi?
This alone suggests the AFM is no longer metering correctly. Your AFR at full noise could be due to toyota ECUs basically flooding the engine at WOT - do you have any AFR readings at part throttle?

As a suggestion, you can put your point across through discussion and reasoning and not through ridicule.
There are plenty of performance shops here that "don't know anything" so the assertion that someone does it isn't necessarily an argument that it's a good idea. A power graph doesn't imply the mod is clearly understood.

Mos.

[slipway NZ]

The car is also running a malpassi RRFPR, Took it round the for a cruize with the wideband on and it was running fun, 12, 13 to 1 ojn cruize so not to bad, also wasnt running a oxy sensor, so that would help at cruizing.

Def works the same.

[slipway NZ]

[hemi twofifteen turbo]

part throttle, basically off boost I would think would be the same as if the AFM was on the inlet side of the turbo. I'm pretty sure slipway knows what he's talking about, and one of his best points is don't say it won't work if you havn't tried it. So many people pass around info they just hear. We all know that, but then there's the people who think about something technically and come to a conclusion why it won't work; be it a little better than someone who's just passing on info, someone who's tried something and it's worked sucessfully will always have much more credibility than someone who hasn't. You can argue forever saying his AFR is not optimial this, that whatever, but being that he is retaining factory ECU, this is a budget setup, and for a budget setup is working very well.

[Mos]

The car is also running a malpassi RRFPR, Took it round the for a cruize with the wideband on and it was running fun, 12, 13 to 1 ojn cruize so not to bad, also wasnt running a oxy sensor, so that would help at cruizing.

Def works the same.

We already know that it doesn't work the same way - purely by your statement that the boost cut increased, meaning the ECU thinks it has less airflow. Your RRFPR will take care of the fueling (albeit badly) with this reduced airflow reading.

The only way you can be sure it "definitely works the same" is by running two identical airflow meters - one before and one after the turbo - and datalogging/comparing the ouput. Unless you, or the performance shop, have done this you cannot make the assertion that it does the same job, especially in the light of the changed fuel cut level.
In addition, I put to you that this reading will not be the same, because the pressure affects the reading.

In variable area flowmeters (such as the toyota flapper AFMs) the volumetric flow rate is proportional to the square root of the fluid density.
http://www.efunda.com/designstandard...owmeter_va.cfm
In hot wire flowmeters, the quantity being directly measured is density multiplied by velocity which is why the Nissan mod in theory should work (although they will gunk up with crap quickly - hot wire relies on very clean fluid) - admittedly this thread is the first time I've heard of AFMs of any type being used on the compressed side.
http://www.efunda.com/designstandard...res_theory.cfm
http://www.freepatentsonline.com/5880365.pdf

So... the theory, and the practise (13psi vs 20psi) disputes the notion that it's Ok to use toyota AFMs after the turbo without aids.

Mos.

[Mos]

part throttle, basically off boost I would think would be the same as if the AFM was on the inlet side of the turbo. I'm pretty sure slipway knows what he's talking about, and one of his best points is don't say it won't work if you havn't tried it. So many people pass around info they just hear. We all know that, but then there's the people who think about something technically and come to a conclusion why it won't work; be it a little better than someone who's just passing on info, someone who's tried something and it's worked sucessfully will always have much more credibility than someone who hasn't. You can argue forever saying his AFR is not optimial this, that whatever, but being that he is retaining factory ECU, this is a budget setup, and for a budget setup is working very well.

While I agree with most points that you raise, I think it's detrimental to be only painting half the picture - slipway did not mention the RRFPR which obviously changes the story regarding "safe" AFRs.

I'm all for people trying things, but I'm not highly respectful of people saying "yeah it will be fine" without sufficient understanding/explanation of the limitations and potential problems - it might seem like i'm harping on the subject of the RRFPR but if it wasn't there the results will almost certainly be a blown engine - in my view this is a *CRITICAL* piece of information and not an "optimal this, optimal that" aside.

Thoughts?

Mos.

[nick.parker]

I for one believe Slipway.....

What I think people dont get is that almost anything can be made to work if you hack around enough, but the result will almost always be a compromise. The question is can you handle the compromise? Slipways dyno for example...what a fuel pig running 10.9 : 1 AFR at lower boost!!!!

[Norbie]

In variable area flowmeters (such as the toyota flapper AFMs) the volumetric flow rate is proportional to the square root of the fluid density.
http://www.efunda.com/designstandard...owmeter_va.cfm
In hot wire flowmeters, there is no such fluid density relationship which is why the Nissan mod in theory should work (although they will gunk up with crap quickly - hot wire relies on very clean fluid) - admittedly this thread is the first time I've heard of AFMs of any type being used on the compressed side.
http://www.efunda.com/designstandard...res_theory.cfm

A friend of mine did the blow-thru AFM mod on his VL turbo, it worked fine and actually made the car drive better because it eliminated a huge amount of piping between the AFM and the throttle. I agree it wouldn't be a good idea with flapper-type AFM's though, they work on a totally different principle to the hotwire AFM in a VL turbo.

[slipway NZ]

O.k, well didnt mean t o start an argument here, but a mate of mine is running a std 1ggte with no fuel reg and it also runs fine, i havnt tried mine with the rrfpr so i wouldnt know.

I was sceptical at first but Boosted performance here in NZ recomended it so i tried it.

As you can see it does run quite a rich tune but thats with the malpassi wound up and no adjustments.

Does anyone know what he boost cut is on a factory ecu? i actually thought it was 18psi so maybe it didnt have much affect at all.

Also toyota ECUs do run really rich factory, can someone post a dyno graph of a 1g runnig normal AFM? just to see what the fueling is like.

Anyways, was merly trying to state that it CAN be done, with some good results i would have thought..
Cheers
click on mike dyno to see vid

http://www.defy.net.nz/lofreq/pics/C...%20dyno%20day/

[Mos]

Moderately modded with factory management.
From: http://www.toymods.net/forums/showth...t=7285&page=15


Mos.