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should i buy a vaccum pump or not?

4K views 32 replies 15 participants last post by  spray power 
#1 ·
I have a sbf 331 stroker nitrous car going to hit it with 200-250 never have used a vaccum pump in the past my friend told me i should get one but i dont know anything about them. if i do need one wich should i get 3vane or 4 if anyone could help i would apreciate it.
 
#6 ·
4 vane pump and record the pan vacuum to detech deadanation in the engine. If you are useing a 7531 you can hook up a map sensor to it and record off that.
 
#9 ·
Does anyone have a part number for the proper map sensor to use with a 7531 box?
 
#7 ·
A vacuum pump is one of the best investments you can make on a nitrous motor, over time they usually pay for themselves by allowing you to see detonation and keeping the cylinders dry. I would also go ahead and get a 4 vane if you can that way you will always have room to grow.
 
#11 ·
Summit says that part isn't available. I'll do some searchong and see what I can find in a single bar 0-5v sensor.

Thanks for the info.
 
#12 ·
There is no reason you shouldn't be able to use an everyday GM 1 bar sensor. They are readily available from any auto parts store. GM used the same sensor on miilions of vehicles. Look at a 1991 S-10 truck for an example.

I would put a vacuum pump on any nitrous engine. Not cheap, but it's certainly worth it. I use the Star Sportsman stuff myself. They have one of the best drive mandrel setups out there.

The worst part of a vacuum pump (next to the price) is mounting it and making it work with any other accessories you already have, Alternator, Power Steering pump, Water pump...........
 
#14 ·
Use the MSD map sensor and same you some troble. MSD makes the plug in a little different than the regular GM map sensors and you will spend some time trying to get it to plug in the MSD 3 pin harness. Yes the MSD is a little more but sames time which is money.
 
#17 ·
It can be obvious, or it can just ba little dip in vacuum at a certain spot. Most cars will raise vacuum going down track, where you will more than likely see it first is on the gear change. Once you see it you can then deside what changes you are going to make to correct the problem. I have seen dips in pan vacuum but not able to see it on the plugs, so if you watch every thing close it will be help full nitrous or n/a.
 
#21 ·
I don't used a Digital 7, but I do have a GM MAP sensor under my dash with a 3/16" or so rubber line going through the firewall to a fitting on the back of the valve cover so it can easily be removed in the rare instance I check my lash. ;)

I had the sensor hooked to my LM-1 at the time so I could record the vacuum during a pass. I also had a regular vacuum gauge on the dash so I could see it going down the track. It certainly saved my ass one night when I tried a "hero shot"! I saw the gauge bouncing-around and instantly kiiled the juice and continued down the track on motor. I saw the same thing on the data logger. When I opened the drain on my breather tank there was a lot of oil in there, normally there is nothing. I'm sure I would have hurt it good if I had made a full-track nitrous pass that night.
 
#29 ·
i have guage on cowl but for some reason i never see it going down track. so i was wanting to log the vacuum to see whats happenig. what location do you mount the rubber hose or the map sensor for logging. i currently have a -4 fitting in valvecover beside vacuum pump line fitting for guage. didnt know if i could tee off of that. or get at another location
 
#22 ·
what is the MSD part # for MAP sensor? will it show in inches of vacuum?
 
#23 ·
what is the MSD part # for MAP sensor? will it show in inches of vacuum?

2311 MSD, and yes it will show in inches of vacuum. It will read map on the trace log.
 
#26 ·
I just looked at one in the shop and it's 2311. They must have changed numbers.
 
#27 ·
The one I was looking at was the 2314 also .
 
#30 ·
that a 4 bar MAP sensor. the 2311 is the 1 bar which MSD no longer sales the told me on the phone today. Pete from MSD said a 1 bar would give best resolution ofr vacuum only use. just need a plain ole GM MAP sensor
 
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