SRV Performance

Easily.

We're tying to get the bare-bones kit to the market first. Extras such as upgrading the other intercooler pipe & putting the air filter behind the headlight will follow immediately afterwards.

J Chen

How much for the MAF sensor alone with Samco couplers ?

Bri Bro

What about the heat generated by the Turbo compressing the air, it can get over 150C. The elevated temperatures will also greatly decrease the life of the electronic devices. Do the car listed above mount the blow through after the intercooler?

mrfixit951

All,

I was able to fit the MAF unit between the intercooler outlet and throttle body inlet. The BOV is located upstream of the MAF unit (important, as the MAf only measure the air flowing past the throttle blades and idle stabilizer). Brian you have a good point about the compressor outlet temperatures. The MAF device is best mounted post intercooler for lower temperature operation. In my orginal discussion with Pro-Flow they indicated a maximum air flow temperature. I think it is in my files somewhere. Elevated temperatures fundementaly reduce the electronics lifetime. In this case I beleive there is an internal electronic limitation within the MAF control electronics. It is not able to maintain the proper temperature differential between the temperature sensor and hot wire as a result of the temperature to voltage scaling limitation internal to the MAF unit.

Also locating the MAF just before the throttle blades and post blow off valve minimizes the delay between the engine air flow changes and sensor's response, along with solving the following issue. In turbo applications with MAF sensors before the turbo inlet the air flowing out of the open BOV often reverses the air flow in the MAF sensor momentatily. This results in a "no air flow signal" to the electronics that must be cleaned up either in hardware of firmware.

SRV's design will suffer from measuring the air recircualted thru the BOV, resulting in an overly rich condition when the valve is open. This is the same identical issue with venting a BOV directly to atmosphere

Ben

macnewma

SRV-

Have you run your car with this setup? How did it run?

DDP

How did I miss this thread??!!


Ben, what do you mean SRVs design will suffer from the recirculated BOV. Wouldn't it recirculate it before the MAF sensor and it would measure it?

Couldn't custom burnt chips solve the running rich issue?

mrfixit951

Derek,

This is a transient rich condition that will occur anytime you abruptly let off the gas (causing the blow off valve to open). Doing this will result in fireballs out of the exhaust during high RPM aggressive shifting. The air circulates in a closed loop (turbo-intercooler-BOV-turbo .. ). This air is measured as being ingested by the engine, while in reality it is not. This results in too much fuel being injected. This issue is transient and can not be massaged out by changing table values.

The location of the MAF sensor in the SRV design, will have large problems with a blown BOV or one that opens during part throttle (dependant on BOV design). In this condition large amounts of unmetered air will be available to the engine, resulting in a lean condition. This is also a condition that you would not want to try to tune out.

I am surprised that the SRV MAF will not fit between the intercooler and throttle blades. My prototype univer fits (tightly), even with it large external sample ring. It may have been because they did not integrate the MAF into the hardpipe, but tried to splice it into the existing pipe with silicone couplings. It would be cool if SRV could incorporate the MAF into a new custom hardpipe located between the intercooler outlet and throttle body.

I would be willing to create an aluminum prototype, if someone (SRV?) provided the MAF (of course the MAF electronics will need to be removed before welding).

Ben

Ben

special tool

The air does not continue to be counted upon closing of the throttle plate because of the bypass valve. The bypass valve pickup is after the AFM/MAF.
Momentary flames upon throttle closure are caused by air contnuing to pass the AFM/MAF because it is a compressable fluid. As it compresses against the throttle plate the AFM/MAF sees it as business as usual for a moment - until it reaches suffcient density as to prohibit further passage of AFM/MAF.

Bri Bro

Here is a picure from the 3000 GT forum by David J of his blow-through MAF. THe MAF is mounted after the Y pipe, just in front of the throttle body.

DDP

So it wouldn't matter if the BOV is located behind the MAF?

Bri Bro

My though is that you want the BOV before the MAF. This way the MAF is only measuring the air flow going into the intake.

Tomas L

Putting the MAF between the Recirculation inlet and outlet like it's done in the pictures would be an extremely bad idea. The problems would be way worse than what normal non blown MAF installations have with backflow caused by the opening of the valve.
Remember that the purpose of the recirculation valve or a BOV is to keep the turbo spinning by allowing it to freely pump air without any opposing pressure. In this case the fast spinning turbo would circulate huge amounts of air through the MAF when the recirculation valve or BOV opens.
It would also allow unmetered air to pass through the BOV into the engine at idle if the BOV is open.

Either the reciculation valve/BOV pressure side inlet must be relocated before the MAF or vice versa. The better solution of these two would be to relocate the MAF. Then it would end up after the intercooler where the temperature is lower and more constant. This would make life easier for the MAF but could also lessen the chance for strange mesurement errors, remember that a MAF really is a fancy temperature sensor and that high and quickly changing temperature may upset it.

Tomas

Bri Bro

Tomas, good point about the air temperature effecting the MAF, with 100C swings in temperature, the MAF could see up to a 10% error. I would think they have a temperature compensation circuit inside the MAF but it would have a lag. That would cause the mixture to be all over the place as you got on and off boost. I would think the setup on the 300 GT would be the way to go.

Tomas L

That's exactly my thought.
And on top of that you may bottom out the temp correction circuits and the current driver for the hot wire if they are not designed for this application.

RolexNJ

To All:

Well, my deal with SRV Performance and getting a new hotwire fell thru. And it wasn't because of them by any means. They were very helpful, professional, and had great follow-up. So kudos to them!

But, I thought I'd share some news with everyone as a result of my experience. This post really relates to what Pro-m is "currently" not doing when shipping new MAFs. And this is from what I just experienced as of a few days ago too. As of right now, Pro-m is "not" shipping any data or spec sheets with their MAFs. They used too with every new unit, but aren't doing it as of right now. For me, I wanted a new hotwire that was calibrated more than the #30, so my unit could flow a little more. Well, I was about to place the order, but, wanted to see the sheet that would show the calibration and it's voltage. And guess what? Pro-m will not give me one. No reason as to why too. Hence, I wasn't about to blindly trust them and buy the piece for my newly built 3.0L 8V. So, I didn't order it. I have "heard" though that in the future they are going to supply each customer with this information. I hope so, for I want a new hotwire/MAF myself!

Anyway, just be careful before you decide to order one of their units. I know the company is still in it's insolvency stage, but still, they shouldn't be selling units that don't have that spec sheet. If you need clarification on this, please ask SVR Performance, not me, I was just a potential customer.

Hope this gives everyone some insight.