think there's a gb running on the hybrids pete.

 

Because the air is compressed in a blow through system there is more volume in a given area that wouldnt normally be there at normal atmospheric pressure.

If you understand how a blow through system works you will have no doubt that it will work perfectly. The resolution will be fine in a blow through state and the fact that it will be in a 75mm pipe will give plenty of headroom in a normal atmospheric environment anyway.

Its being used by guys in the states running over 600WHP without trouble. As for custom pipework, thats easy covered as i make it all myself. Not that it needs altering much. Just the addition of a stainless MAF boss on the cold side pipe and the blanking of the MAF boss on the APS CAI kit. I may even junk the APS CAI kit all together as at that point it will do nothing for my car.

 

Surely the MAF will read a much greater mass of air as a result of it being post turbo and reading compressed air? As a result reaching the uppermost point of the output voltage at a much earlier point.... I have read examples of people maxxing this out at just under 1 bar with the fp green.

 

M ***
A ir
F low

 

Wow, this is almost like reading up on the 22B site, way too clever for me

What I don't understand is why anyone would want to retain a sensor (MAF)that is fundamentally unreliable in a system, when it can be removed? Is there an advantage, that makes retaining it sensible?

 

Yes - So it is measuring more mass because it is more dense/pressured.

More mass = higher voltage output from the sensor.

 

Yes Neil it wants to be kept with good reason.

Firstly the MAF system is fine if looked after and is plenty reliable enough. MAP sensors cannot detect a change in outside air pressure, also the MAF can be used to monitor the actual air charge temprature within the system.

MAP sensors are okay but a MAF based system is far more accurate for the job in hand.

I'll keep the MAF setup as long as possible, and will cross the bridge to something else if and when it may be required.

 

Take your engine as an example and do the math; 2.5ltr, FPGreen 8cm, 3" inlet, UK STi heads/cams, 3" decat exhaust, GTSPEC headers.
Calculate the volume of each cylinder, head gasket, combustion chamber and dish, take your deck height.
Next calculate the swept volume of each cylinder, the compressed volume and the static compression ratio.
Measure the pressure drop of your intake system and do the same for your intercooler and associated plumbing.
Now take your valve lift, lobe centres and cam timing and look at dynamic compression.
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With all these calculations and the data you now have at your disposal, what is the mass flow of your engine operating at 6000rpm and 1.5bar at sea level with an ambient temperature of 28degC?

 

Obviously I havent got all that exact data Zak but I do know that mine consumes 410 grams/sec of air at that level, but we are not talking about my engine. We are talking about frayz's current engine, not the new one that will be similar in spec to mine.

As you know me very well I have some questions:
a. will the MAF sensor output a higher reading on blow through rather than pull through because of the greater mass/density of air assuming the same diameter of pipe? - (i appreciate that you will probably mount in a larger pipe)

b. will the maf be able to cope with the added stress of being hot side or cope with the extreme pressure/heat differentials?

c. will frayz's ecu be able to read the new output and associate that with an appropriate g/sec for mass air flow within his maximum level of 300 g/sec. Or will this require more 'adapting' of tables in there to effectively give that headroom?

d. will this be worth it when a MAP based system is ultimately a much easier system to map on the car?

I do however hope this works from a point of view of getting rid of the erratic behaviour caused by the removal of the dump valve, but surely the simple solution is to put a recirc dump valve back on.

I will look forward to seeing how it goes

 

Forget Frayzers engine, I used yours as I thought it would be easier for you to relate to. Do the math, you may be surprised

In answer to your questions.......

• a - an increase in mass flow will increase voltage
• b - only time will tell with this particular MAF sensor, I've used later but yet to try this MY
• c - the ECU would have to be rescaled with the increased capacity
• d - you of all people should know that I wouldn't recommend anyone spending money where they don't need to, cost of a Simtek for this car is £1095+vat. Yes mapping would be easier/quicker as the Simtek allows live mapping rather than log, analyse, flash, log, analyze, flash, log.........

Erratic behaviour from removal of dumpvalve he's being a tart and using it is an excuse to add a little bling to the engine bay it's no worse than running a FMIC with a dumpvalve on a draw through system. I certainly didn't feel anything erratic in it's behaviour.

 

Hmmm, OK. I assume the later ones are more reliable.
I am just a bit biased as the last time my scoob let me down was late at night out past canewdon, not a house it sight. Cause - yep MAF failure.

 

Zak, how dare you!
We all know Frayz doesn't fit anything onto the car that isn't necessary (well apart from shiny diff guards)

 

Ha ha ha...

Zak is probably the only person that will ever get away with that ha ha ha.

 

Cheers for the replies Zak.

Any plans for the size of the blow through tube to give the extra headroom for the output voltage and ways of avoiding turbulence around the sensor (if there is a step in pipe ID's) as this seems to be a big issue with BT systems. A lot have gone with a GM honeycomb mesh pre maf sensor to try and calm the airflow down.

It will be interesting to see how it improves things (if it does) and how long the maf lasts but then I guess frayz's car doesnt get much mileage. I know my maf is on the way out and would love a system to get rid of it rather than spend best part of £350 to get a new one.

 

Ive decided the cars not going to WRC and is coming off the road at the end of the month

 

About bl##dy Time!

Look forward to seeing the progress charted on here

 

Lol,

You cant rush perfection my boy...


i took a whole 9 months to make

 

Looking forward to reading it...

Make sure the're pics otherwise we won't forgive you!

 

Cant promise a million pics but im sure i'll get a few along the way

Hopefully gonna make a start on measuring and prepping the internals next week

 

Should have put you back for another 9!

 

This thread's taken a turn for the technical, fascinating reading for us mere humans.

Good to hear you are getting round to the engine at last, makes all those hours of overtime seem worthwhile

 

buggsy a ride when the 2.5's in. although i think i need a ride in it with the 2.0 so i can compare them

 

Welcome to take it anytime Matt.

 

ra is going into Zak on the 30th for it's first Mocom Magic session. Having the geometry set up

follow has been done / is being done before it goes in:

whiteline front arb 22mm - check
whiteline front solid drop links - check
whiteline alk - to do
whiteline rear adjustable arb - check currentley on medium setting
whiteline rear solid drop link - check
cusco front lower h brace - check
cusco rear diff brace - to do
front upper strut brace - check
rear upper strut brace - check
cusco coilovers (cheers Dazza) - check

in a couple of months i'll have the rear adjustable control arms off Zak and a couple of sets of adjustable camber bolts. think i'll get used to all the above with a good setup first

guess i should get it as stripped out as it's going to be when finished before the setup. or will that not matter?

 

No need for camber bolts with the adjustable rear arms Matt, saved yourself some dosh there

 

Id be adding some noltec topmounts to that little listy. They wil give you SOOOOOOO much more than the ALK.

 

With all this stiffness will you be approaching Viagra for sponsorship

Sounds good and the adj rear control arms have been on my mind too

 

so none at all or still get them for the front or are they not needed?

 

was looking at those as well. will have to get those a month or 2 after

 

will be starting to look for sponsors for next year. looking at entering a few hill climb events