[DeTomaso] Vacuum source on IR manifolds

Ed Mendez edducati at mac.com
Sat May 26 01:58:35 EDT 2018


Here is a picture of mine. I have a line going to each runner then all to one small common block for brakes and MAP. I am running indexed speed density mode on my FAST XFI 2.0, I have have two MAP sensors one for manifold absolute pressure and one for barometric pressure, it takes a reading form both and adjusts for elevation. I am not running an IAC because as the article states below you would have to have two lines plumbed to each port.

Here is a section from a forum when I was doing research.

======
Perhaps add a vacuum reservoir to act as a "shock absorber" and give a more even MAP reading, go speed density for the tune. For the map signal, you need a vacuum feed from each port, tied into a common "metering block" and then to the map sensor. You cannot take a vacuum signal from a single port, needs to be from all of them. You also don't want to share that vacuum source with the iac or anything else. They make nice remote mount iac's, but again they need their own separate lines to each port. Think of something like a port-injected nitrous system with the stainless hard lines going to each port in the intake and tieing together in a billet aluminum block. On mine, there were two lines to each port hidden underneath the manifold just like a hidden nitrous kit. Then after the block where they came together we put two bulkhead fittings in the rear of the intake (one for iac and one for map) so there was a connection from the top of the intake. Totally hidden, very clean looking and works perfect.

Using a SMALL plenum for the vacuum is a requirement - not an option - otherwise you have nowhere to take the MAP reading. There is very very little vacuum signal from these types of intakes. I would advise you to use the plenum for ONLY the MAP signal. I was trying to remember - but think I could only get 4 or 5 inches of vacuum reading at my plenum. The pulse signal is soooooo weak without having a large common plenum of the dual plane / single plane intake....

To help tune the idle circuit -- in the efi maps -- you make smaller incremental 
grids in the idle vacuum and rpm map.... then you can tune out the lumps easier with finer control... and also using the idle spark add or subtract. 

IMHO, a guy that's GOOD with these ECU EFI systems can make anything/combo run like a swiss watch. 

I just finished helping a buddy with his 8 stack (Imagine Injection) install - using Fast XFI on his 454 big block. It started the FIRST TIME - in about 3 rev's - once I tweaked the distributor timing to actually match the ECU - it purred... and there's nothing like the sound of air being gulped one cylinder at a time.
======

In reading this however, I have the single lines to each port “the black lines in the picture” I have them going to a tiny plenum and have my brakes and MAP going to it and have no issues at all. 

I suppose this depends oil if you have a huge cam or not, in that case Don Byars makes this bitchin vacuum pump setup the for brakes that fits underneath and in front of the radiator.

Ed
> On May 25, 2018, at 22:28, Robert Stroj <npdrs at maui.net <mailto:npdrs at maui.net>> wrote:
> 
> Hi, I am in process of installing IR fuel injection, using Fast Xfi 2.0.
> Would like to hear from someone running similar setup how did you plumb vacuum source manifold.
> Was planning to use just one common manifold (connected to all 8 runners) and then connect servo brake tube, MAP sensor and vacuum regulated fuel pressure regulator all to that manifold.
> Would that work fine or will signal from MAP get wrong readings when breaking (booster maybe reducing vacuum)?
> If this is fine, is there some rule on how to size this manifold?
> 
> Thanks, Robert 
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> 
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-------------- next part --------------
   Here is a picture of mine. I have a line going to each runner then all
   to one small common block for brakes and MAP. I am running indexed
   speed density mode on my FAST XFI 2.0, I have have two MAP sensors one
   for manifold absolute pressure and one for barometric pressure, it
   takes a reading form both and adjusts for elevation. I am not running
   an IAC because as the article states below you would have to have two
   lines plumbed to each port.
   Here is a section from a forum when I was doing research.
   ======
   Perhaps add a vacuum reservoir to act as a "shock absorber" and give a
   more even MAP reading, go speed density for the tune. For the map
   signal, you need a vacuum feed from each port, tied into a common
   "metering block" and then to the map sensor. You cannot take a vacuum
   signal from a single port, needs to be from all of them. You also don't
   want to share that vacuum source with the iac or anything else. They
   make nice remote mount iac's, but again they need their own separate
   lines to each port. Think of something like a port-injected nitrous
   system with the stainless hard lines going to each port in the intake
   and tieing together in a billet aluminum block. On mine, there were two
   lines to each port hidden underneath the manifold just like a hidden
   nitrous kit. Then after the block where they came together we put two
   bulkhead fittings in the rear of the intake (one for iac and one for
   map) so there was a connection from the top of the intake. Totally
   hidden, very clean looking and works perfect.
   Using a SMALL plenum for the vacuum is a requirement - not an option -
   otherwise you have nowhere to take the MAP reading. There is very very
   little vacuum signal from these types of intakes. I would advise you to
   use the plenum for ONLY the MAP signal. I was trying to remember - but
   think I could only get 4 or 5 inches of vacuum reading at my plenum.
   The pulse signal is soooooo weak without having a large common plenum
   of the dual plane / single plane intake....
   To help tune the idle circuit -- in the efi maps -- you make smaller
   incremental
   grids in the idle vacuum and rpm map.... then you can tune out the
   lumps easier with finer control... and also using the idle spark add or
   subtract.
   IMHO, a guy that's GOOD with these ECU EFI systems can make
   anything/combo run like a swiss watch.
   I just finished helping a buddy with his 8 stack (Imagine Injection)
   install - using Fast XFI on his 454 big block. It started the FIRST
   TIME - in about 3 rev's - once I tweaked the distributor timing to
   actually match the ECU - it purred... and there's nothing like the
   sound of air being gulped one cylinder at a time.
   ======
   In reading this however, I have the single lines to each port "the
   black lines in the picture" I have them going to a tiny plenum and have
   my brakes and MAP going to it and have no issues at all.
   I suppose this depends oil if you have a huge cam or not, in that case
   Don Byars makes this bitchin vacuum pump setup the for brakes that fits
   underneath and in front of the radiator.
   Ed [cid:BB9234B6-5F88-4571-A521-3C6B9693C26D]

   On May 25, 2018, at 22:28, Robert Stroj <[1]npdrs at maui.net> wrote:

   Hi, I am in process of installing IR fuel injection, using Fast Xfi
   2.0.
   Would like to hear from someone running similar setup how did you plumb
   vacuum source manifold.
   Was planning to use just one common manifold (connected to all 8
   runners) and then connect servo brake tube, MAP sensor and vacuum
   regulated fuel pressure regulator all to that manifold.
   Would that work fine or will signal from MAP get wrong readings when
   breaking (booster maybe reducing vacuum)?
   If this is fine, is there some rule on how to size this manifold?
   Thanks, Robert
   _______________________________________________
   Detomaso Email List is not managed by POCA
   Posted emails must not exceed 1.5 Megabytes
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   To manage your subscription (change email address, unsubscribe, etc.)
   use the links above.
   Members who post to this list grant license to the list to forward any
   message posted here to all past, current, or future members of the
   list. They also grant the list owner permission to maintain an archive
   or approve the archiving of list messages.

References

   1. mailto:npdrs at maui.net
   2. mailto:DeTomaso at server.detomasolist.com
   3. http://server.detomasolist.com/mailman/listinfo/detomaso
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