North American Turbocoupe Organization



Placing VAM after the turbo, does it work?
svo_thunderchicken Offline
Senior Member
#1
If i place the vam AFTER the turbo, how will it affect the vam? will it even work? I would really love to relocate the vam inline on the output of the FMIC im going to install :-)
84 TC Silver 5 speed - PE EEC, Big Vam, RR cam, 35lb injectors, E6 swap, T3 60 Trim, 87-88 intercooler and hood, BOV, K&N Cone Filter *under constrution*
http://www.cardomain.com/ride/2298891/1

87 TC Black 5 Speed - Stock IHI, BCS Bypassed
http://www.cardomain.com/ride/2390431
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Pete D Offline
Administrator
#2
It's been done, check at TF
Pete Dunham


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trashline Offline
Posting Freak
#3
ford designed it to moniter air being drawed in.have you ever played with the door on a vam? the spring i thin kis bairly enough to make the door work in the conditions it is in now the slightest amount of air would probably have great effects on your idle. if you even pump the vm it will affect the idle as the door will move slightly. the vam lets in different amounts of air at a givin time now i dont know if it happens while the car is in boost or not but if the vam only opens half way when your at 5 psi but b/c it would be pressureized the vam door would probably open all the way and great a lean condition with the door being opened. i dont under stand why you cant put it on the inlet of the turbo? i wonder if you could think of it as a draw thru carb vs a blow thru. blow thru has to be setup for boost need to block off the air vacuum line from the mech choke if it has one and you need to use a solid float as it will colapse it. nitrophyl is wha they use. a draw thru nothing has to be done to the carb.

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1966 mustang
1988 tbird
Finally have mods that I can post... 373 gears with a brand new t5. K&N cone. Gillis set to 15 psi. Walbro 255 lph. Kirban afpr. Kelly Evo Z tires. Energy suspension front swaybar bushings. Rebuilt topend with stock components.

Working on a FMIC w/ the stock IC.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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trashline Offline
Posting Freak
#4
guess i was wrong if my hypothesis oh well. whats wrong with where it was ?

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1966 mustang
1988 tbird
Finally have mods that I can post... 373 gears with a brand new t5. K&N cone. Gillis set to 15 psi. Walbro 255 lph. Kirban afpr. Kelly Evo Z tires. Energy suspension front swaybar bushings. Rebuilt topend with stock components.

Working on a FMIC w/ the stock IC.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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Joe F Offline
Posting Freak
#5
The mod you refer to is called a "blow-through" VAM; as previously stated several folks on Turboford have done it for whatever reasons. You might check there.

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Joe F.
JR's Aerie - Our 3 TC's
JR's Place - My '87 Turbocoupe
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JohnL Offline
Senior Member
#6
The VAM is a big restriction in the 300+ HP range. Moving it will improve your pressure ratio at the same boost level, turbo doesn't work as hard, and boost is cooler and more dense. The pressurized side of the turbo doesn't have the pipe size restrictions of the inlet and therefore the VAM is not a restriction on the charge pipes. Some people have it work well, great improvement in throttle response, some couldn't get it to work good, definately have a wideband if you're going to do this.
John Lewis
88 TC, 87 XR, 84 SVO
Currently deciding which is worth my time.
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Joe F Offline
Posting Freak
#7
Thanks, John. I never really saw why until now. Turbo pressure ratio makes a lot of sense.

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Joe F.
JR's Aerie - Our 3 TC's
JR's Place - My '87 Turbocoupe
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Keith Nubel Offline
Posting Freak
#8
I would like to see the proof that it's an improvement. Blow through or suck through, the turbo is still dealing with the same pressure drop within the same sealed system. How do you deal with the temperature sensor in the VAM?

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85.5 TC 5 speed, Ranger Roller cam, 3" exhaust system, manual boost valve, large VAM, SVO PE computer, front mount Motorsport intercooler & sport grille, ported upper and lower intakes,flow matched injectors, ported E6 manifold, 245/45/17 wheels & Tires,Motorsport 140 mph speedometer,Motorsport lowering springs, Kenwood EZ500 200 watt receiver with Cerwin Vega speakers sound system, air conditioning converted to R134A and Sanden compressor retrofit kit installed, under restoration
1985 TC
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Jeff K Offline
Administrator
#9
With VAM on outlet side of the turbo, the VAT will see very high temps. EEC thinks these temps are very hot ambient intake air, and will drop the timing way back for "safety".

In the long term, VAM life may be reduced (possibly significantly) since it was never designed to be exposed to 300+ deg air temps encountered during high boost.

I know some people at TF have tried it, but I seem to remember them having lots of trouble, having to adjust the spring, etc. I dont seem to remember anyone saying it was a big improvement. The main thing I seem to remember is it makes the turbo louder.... big deal. Also if the VAM is under pressure it may blow off the black plastic cover.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 23 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car) // 91 Topaz (daughters first car)

[This message has been edited by Jeff K (edited 09-17-2005).]
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Keith Nubel Offline
Posting Freak
#10
If you made his change. it seem like you would have to relocate the air temperature sensor.

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85.5 TC 5 speed, Ranger Roller cam, 3" exhaust system, manual boost valve, large VAM, SVO PE computer, front mount Motorsport intercooler & sport grille, ported upper and lower intakes,flow matched injectors, ported E6 manifold, 245/45/17 wheels & Tires,Motorsport 140 mph speedometer,Motorsport lowering springs, Kenwood EZ500 200 watt receiver with Cerwin Vega speakers sound system, air conditioning converted to R134A and Sanden compressor retrofit kit installed, under restoration
1985 TC
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