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Premium Member
1986 Bronco Eddie Bauer 5.0 mostly stock
Joined
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1,833 Posts
Maybe not keeping with the method of the thread, but within the subject matter of the thread, I'd like to ask a question from the side of ignorance and just thinking out loud...
Anyone know how much vacuum is needed for SD to operate properly? Also is this only at idle or does the vacuum effect it throughout the RPM range?
Where I am going with this, and it's probably a dumb idea...but what about an auxillary vacuum pump plumbed into the vacuum system? If you knew what pressure the SD system liked, you could fool it with small pump maybe?
I'm guessing this may not be a good idea because if i understand it correctly, this also tells the ECM how much fuel to send and you could run into a rich/ lean scenario...but if its only an idle issue and once it gets up enough RPM to make the SD "happy" you could operate the auxillary pump with an RPM activated switch (like use commonly in nitrous applications).

Im sorry, im on a boring conference call
 

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Premium Member
1986 Bronco Eddie Bauer 5.0 mostly stock
Joined
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1,833 Posts
I'd rather keep this simple and related to the Vacuum with SD EFI. You can install larger injectors if needed and have someone adjust the constant in the program or whatever is available to correct for the injectors.
If you're going to have to monkey with the programming for the injectors (provided you plan on exceeding the 260 hp mark), might as well go ahead and upgrade the ECM to something like PiMPXS..then you can run whatever cam you want within reason and keep the SD

Also, this particular use of a vacuum pump would be "experimental" i suppose, but they are used quite a bit in forced induction applications, plumbed into a reservoir then all the vacuum operated goodies like HVAC and Power brakes run off of it.

The first Gen Z-r1 corvettes from the 90's had a dual runner setup on their LT-5 DOHC engines, and when you put the engine in "Full" performance mode, this activated a small 12v vacuum pump that would open the secondaries under full throttle giving you all 405hp. I had one of these and that pump in particular is what made me think of the whole "auxillary vacuum pump" idea. 405 HP out of a naturally aspirated 350 engine in the early 90's wasn't too shabby.
 

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Premium Member
1986 Bronco Eddie Bauer 5.0 mostly stock
Joined
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1,833 Posts
You want to "debate" and stick to "Facts" and the info supplied is that Rhodes very well MAY solve the problem I agree with your hypothesis, but the fact remains that nobody involved with this discussion so far, nor that i have seen has tested it, so its just as experimental as anything else mentioned. I don't want to be a guinea pig on this when there is already a proven solution in the form of computer friendly cam/lifters.
If someone was to try the rhodes lifters, they would have to do some major engine dissasembly, break in the new lifters to the cam, and hope that it works out for them...and if it does great, but if not...they got to go back in and buy a new cam setup, gaskets, engine oil, etc.
I get the spirit of the conversation, and it's truly an interesting idea, just a hard sell whenever theres already a solution for that particular problem...unless I'm missing something which is entirely possible.
I have read about the variable venturi carb, but one of the greatest pokes in the eye that i like is when Honda put their CVCC tech on an Impala in the 70's to prove there was a better way to lower emissions and make more power doing it. If you've never read this (you probably have) its very interesting.

 
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