Silvertop 20v map vacuum

Edwin909
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Posts: 12
Joined: Wed Mar 13, 2013 7:46 pm

Silvertop 20v map vacuum

Postby Edwin909 » Thu Jan 22, 2015 7:59 am

hi guise i have a 20v st running megasquiert ms2 and im just wondering what the proper way for the map sensor to draw vacuum from the engine would be.
ive looking around the webz and found this setup
http://www.midrear.net/images/projects/ ... mtank2.JPG
he drilled two holes on cylinder 2 and 3 of the intake ports and ran all 4 holes(these holes draw vacuum from behind the butterfly) to a vacuum canister plus the fpr and what im guessing is the map
currently my map setup draws vacuum from the cylinder #4 itb hole only
is it worth drilling those 2 holes out or will it not make much difference
getting my setup tuned soon and id like the best results
ive also heard of tuning the itbs with the tps sensor only and forgoing much of the map sensor but i dont have much knowledge on that
thanks for your time

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jondee86
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Location: Wellington, New Zealand

Re: Silvertop 20v map vacuum

Postby jondee86 » Thu Jan 22, 2015 1:40 pm

When you are using the full 20V intake manifold, the best way to
get a vacuum signal for a MAP sensor is to tap into the common
vacuum rail as explained here...
http://forums.club4ag.com/zerothread?id=100874
The vacuum rail is connected to all four intake runners via the
ISCV ports, and so it is averaging the intake vacuum for you.

It is possible to tune by TPS or by TPS/MAP blend, but if your
engine is stock, a MAP tune is recommended. Bear in mind that
the AE111 blacktop has a MAP sensor setup from the factory.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

Edwin909
Club4AG Regular
Posts: 12
Joined: Wed Mar 13, 2013 7:46 pm

Re: Silvertop 20v map vacuum

Postby Edwin909 » Thu Jan 22, 2015 2:33 pm

Thanks for the link, seems to me that it works, would you recommend a vacuum block to run off that and feed the map and brake booster?.... Also a bit confused that they mentioned to leave the intake side open to the air but with a filter on it?....

Any way you can drop some knowledge about tunning with tps or tps/map blend like you mention?.. Pros and cons?... I'd gladly appreciate it

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jondee86
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Re: Silvertop 20v map vacuum

Postby jondee86 » Thu Jan 22, 2015 4:06 pm

That thread I linked got a little weird towards the bottom :) I think
that advice related to putting a filter on the ISCV intake if you delete
the factory airbox, which I guess you will be doing.

Standard brake booster arrangement is to take vacuum from the side
tappings on #1 and #4 throttles. These are combined on the factory
setup. Indications are that just one of these tappings will give enough
vacuum for satisfactory operation. You can tee the FPR and MAP sensor
off the same piece of tube that you hook up to the common vacuum rail.

I'll let someone more qualified on MS get into the detailed benefits and
what is involved in implementing alternative tuning strategies. There
are some very knowledgeable people available on these boards who can
advise you how to get your car driving with the least amount of work.

However, the basic reason for using TPS/MAP blend is because of the
large throttle area of ITB's. They have very little manifold vacuum once
the throttles are more than 25-30% open. So MAP sensing no longer works
for load control... this is the region where TPS sensing is more effective.
At low throttle openings, MAP sensing is more sensitive that TPS, and
allows for better tuning. ITB mode (which is the new MS name for TPS/MAP
blending), allows each load sensing mode to used in the region where it
is most effective... best of both worlds situation :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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