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Vacuum Pump on an Ls7

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Old Sep 26, 2017 | 05:01 PM
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From: Michigammiii
Question Vacuum Pump on an Ls7

Lots of great info in this thread if you'd like to refer to it: https://ls1tech.com/forums/generatio...installed.html

As far as the physical installation of one of these goes, how is everyone pulling vacuum towards the bottom of the block? I'm just taking an uneducated guess that a 1/8" or 1/4" NPT drilled & threaded hole in each "bay" of the block, staggered on both sides? This makes the most sense to me in my head, but I don't have experience with vacuum pumps. My valve covers and valley cover both have provisions for a vacuum source, but was curious about the bottom end of the block where it really matters, from what I've found. .

Also, I'm building a dry sump tank to suit my chassis. Do I need any kind of breather or an evacuation line that the vacuum pump should be pulling on it? I haven't been able to source this information.

TIA!
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Old Sep 27, 2017 | 10:45 AM
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Default Dry Sump = Low Crankcase Pressure

Hi Bird, I make/design Dry Sump Oil Pumps.

This design ALLOWS for LOW Crankcase Pressure.

You STATE to run BOTH ?

Lance
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Old Sep 27, 2017 | 01:40 PM
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Originally Posted by Pantera EFI
Hi Bird, I make/design Dry Sump Oil Pumps.

This design ALLOWS for LOW Crankcase Pressure.

You STATE to run BOTH ?

Lance
Sorry, I did not include details on my system. Running a ZR1 LS9 pan and oil pump. This pump only has 1 scavenge side. I like the idea of having an external vacuum pump because it allows me to remove it completely or adjust it easily based on current needs. The engine will have provisions for Katech piston oil squirters for safety. Initial run up and break in will be naturally aspirated, and then shortly thereafter we'll start tuning in up to a 300 shot. The rings will be opened up during initial assembly to allow for this large of a shot.

Thanks.
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Old Sep 27, 2017 | 03:06 PM
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Drawing from the valve cover has always worked best for us. There always seems to be too much oil present in the valley and other spots. Some road race applications can benefit from drawing from multiple locations to help with oil control. This is because road racers, unlike drag racers, do a lot of braking and cornering, making the oil slosh everywhere. Drag cars always work best in the front portion of the valve cover.

Your dry sump tank needs to be vented, and the crankcase needs to be sealed.
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Old Sep 27, 2017 | 04:52 PM
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Originally Posted by nhra686
Drawing from the valve cover has always worked best for us. There always seems to be too much oil present in the valley and other spots. Some road race applications can benefit from drawing from multiple locations to help with oil control. This is because road racers, unlike drag racers, do a lot of braking and cornering, making the oil slosh everywhere. Drag cars always work best in the front portion of the valve cover.

Your dry sump tank needs to be vented, and the crankcase needs to be sealed.
That's a good point about pulling from the front of the VCs in drag applications - probably 25% of my time with be at the drag strip with the other 75% being street, for the most part. I hadn't really considered that. Thanks for the note on venting the oil tank, too. I can easily add that in.

Now I'm not trying to refute the last point you mentioned, and I appreciate the help of an expert, I just want to understand it better (my inexperience with these systems has no credibility, so my mind is trying to put some pieces together and call it "logic"). Everywhere I've looked, I've found GZ Motorsports has the best vacuum pumps for these engines, so I'm trying my best to be humble and not look like an internet expert when I'm far from it in reality. I'd appreciate some clarification!:

Isn't the most amount of blow by going to stay in the bottom end, causing parasitic loss with the crank rotation and piston stroke coming down? Or would the vacuum on the valve covers be sufficient to sustain a vacuum down low? I want to think that with my ring gaps I would benefit greatly if there was a direct vacuum source pulling down low, but I may be overthinking it! I'd really like to be able to wrap my head around it, and I think I should still get in touch with you, personally, later on when it comes time to add the vacuum pump system and storage tank so you can get me properly set up (externally).

Thanks!
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Old Sep 27, 2017 | 10:28 PM
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Your engine has enough air passages between the heads and crank area that any pressure differential will equalize almost instantly. every time a piston goes down, another one is going up, so the only pressure is from blow-by.

You can call or email me any time all the contact info is on our web site.
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Old Sep 28, 2017 | 06:42 AM
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Originally Posted by LS7Bird
That's a good point about pulling from the front of the VCs in drag applications - probably 25% of my time with be at the drag strip with the other 75% being street, for the most part. I hadn't really considered that. Thanks for the note on venting the oil tank, too. I can easily add that in.

Now I'm not trying to refute the last point you mentioned, and I appreciate the help of an expert, I just want to understand it better (my inexperience with these systems has no credibility, so my mind is trying to put some pieces together and call it "logic"). Everywhere I've looked, I've found GZ Motorsports has the best vacuum pumps for these engines, so I'm trying my best to be humble and not look like an internet expert when I'm far from it in reality. I'd appreciate some clarification!:

Isn't the most amount of blow by going to stay in the bottom end, causing parasitic loss with the crank rotation and piston stroke coming down? Or would the vacuum on the valve covers be sufficient to sustain a vacuum down low? I want to think that with my ring gaps I would benefit greatly if there was a direct vacuum source pulling down low, but I may be overthinking it! I'd really like to be able to wrap my head around it, and I think I should still get in touch with you, personally, later on when it comes time to add the vacuum pump system and storage tank so you can get me properly set up (externally).

Thanks!
I run the GZ kit on my ls7 in my z06. Its a great kit and I've had no issues. Still need to hookup a permanent vacuum gauge though. I am drawing from the valve cover. As mentioned theres plenty of air passages in the engine to allow this to be a good place to draw from. In fact most GZ kits pull from the VC.

If you have any questions feel free to ask. I have all the ports on the engine plugged up and the oil tank vented
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Old Sep 28, 2017 | 03:38 PM
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You guys are great! Thanks a bunch.
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Old Oct 2, 2017 | 11:26 AM
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Put GZ pumps on a few LSx engines! They work great. A little pricey for what they are.... but gets the job done.

This is a wet sump LS7 in an RX-7 with Fbody accessories and a/c.
Attached Thumbnails Vacuum Pump on an Ls7-richls7engineside.jpg   Vacuum Pump on an Ls7-richls7fdengine.jpg  
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Old Oct 3, 2017 | 08:00 AM
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Originally Posted by gnx7
Put GZ pumps on a few LSx engines! They work great. A little pricey for what they are.... but gets the job done.

This is a wet sump LS7 in an RX-7 with Fbody accessories and a/c.


That looks nice (and tight!). I'm wanting to put one on my build but I'm using the Vintage Front Runner system (w/ac) and both heads are covered up pretty good making the GZ bracket worthless. When I get the engine installed (hopefully today) I'm going to look at designing a bracket that will work with my mess...
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