Corvette Performance - Revised GZ Motorsports Vacuum Pump (C5)

I didn't like how the 22.5" belt, which came with the LSx kit, set the pump/inlet fitting so close to the coolant reservoir. After some searching, I found a 21" belt. After moving the pump away from the reservoir, I had an issue with it hitting the Katech tensioner, so I picked up the GZ tensioner. Problem solved. Also, being an ARP junkie, I had to upgrade a few fasteners in the kit.

With Katech valve covers, I wasn't able to use the nifty GZ oil fill cap, which houses the pickup and regulator, so I had to set up my own arrangement. Wanting to have the vacuum regulator plumbed into the pump inlet (rather than the valve cover) and wanting to keep things somewhat clean, here is what I came up with...

http://i27.photobucket.com/albums/c151/rlsracing/photobucket-35630-1339125716461.jpg

http://i27.photobucket.com/albums/c151/rlsracing/photobucket-37118-1339126050915.jpg

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I drilled/tapped a 3/8" NPT port into a Fragola 90-degree fitting...

http://i27.photobucket.com/albums/c151/rlsracing/photobucket-1301-1339125608826.jpg

I like it. Wish I had the room.

Very good fit. My pump loosened up and moved a little, and the tensioner quickly rubbed a long cut in the pump casing, clear thru. Good ole JB Weld patched it up. Looks like crap now. I guess I need to sand it and polish a little.

The tentioner is just too close to the pump and leaves only about a 1/4 inch for adjustment. Not a good pic but you can see how close they are

http://i895.photobucket.com/albums/ac152/Pit-man/DSC05594.jpg

The tensioner is just too close to the pump and leaves only about a 1/4 inch for adjustment. Not a good pic but you can see how close they are


I noticed that the GZ manual tensioner gives you more room to work with, as far as having the option to rotate the pump back towards the centerline of the engine. Also, it makes for a more, IMO, stable setup, as the stock tensioner will shudder or move around a bit on the spring. Given that it's close proximity to the throttle body, in my application, I feel more comfortable with a solid tensioner. So far so good... I'm only running around 7" at WOT and it tends to stay below 5" (2-4") while cruising around. I added an auxiliary reservoir that fastens to the radiator support so the GZ catch can only acts as a ventilation chamber, so to speak. I ran a -6 hose off the bottom of the catch can, into a 2" diameter reservoir that's mounted horizontally, under the car. I haven't noticed any "oil odor" since adding this deal. The vapors can collect/move thru the can while the fluid drains into the reservoir.

I noticed that the GZ manual tensioner gives you more room to work with, as far as having the option to rotate the pump back towards the centerline of the engine. Also, it makes for a more, IMO, stable setup, as the stock tensioner will shudder or move around a bit on the spring. Given that it's close proximity to the throttle body, in my application, I feel more comfortable with a solid tensioner. So far so good... I'm only running around 7" at WOT and it tends to stay below 5" (2-4") while cruising around. I added an auxiliary reservoir that fastens to the radiator support so the GZ catch can only acts as a ventilation chamber, so to speak. I ran a -6 hose off the bottom of the catch can, into a 2" diameter reservoir that's mounted horizontally, under the car. I haven't noticed any "oil odor" since adding this deal. The vapors can collect/move thru the can while the fluid drains into the reservoir.

Sounds like a good idea. The fumes get sucked right in my cabin...stinks terrible. I have been running 12lbs for racing and on the street.

Here:

http://i27.photobucket.com/albums/c151/rlsracing/photobucket-35362-1344218421769.jpg

I used some 2" diameter exhaust tubing and a couple of thick shock washers I had layin' around, and then sourced some Fragola fittings from the local speed shop. Tapped the center hole of the washer on the inlet side of the tank, welded up the center hole on the outlet, and then drilled/tapped an offset drain hole on the outlet side. Welded some tabs on it, shot it with some rustoleum, and viola.

Awesome work.

Thanks

what gains have you seen with the gz pump?

I've seen them only a few times used by Charlie@RPM

that's got to be one of the best looking/no BS engine bays on a C5, very nice.

Thanks man...

I haven't had the car on a dyno yet. Almost 2500 miles into this deal, and I've only made a few 1/8 mile hits (mid 2 second 60 ft. times, trapped 101mph). I attempted to make some 1/4 mile hits last Friday, but broke something inside the (stock 3-rib out of an '02) diff on my first try, right before the 60ft. mark. It's time to upgrade to an RPM diff.

Regardless, I don't believe I'll do any back-to-back testing to see what sort of difference the pump makes in HP. I'm more after the anti- oil contamination benefits the pump brings to the mix. It's much more effective than the PCV catch cans and the regular catch cans plumbed right to the valve cover(s).

what gains have you seen with the gz pump?

I've seen them only a few times used by Charlie@RPM

that's got to be one of the best looking/no BS engine bays on a C5, very nice.

I talked with a couple of the guys at the PRI Show in Orlando and they both claimed up to 20hp gains. I did not see any difference at all in my ET, but the pump sure cleaned up all my pressure problems.

I ran 11.17 & 11.18 ET in some 40 degree air here in Florida, back in January,2010 without the pump. I was at Gainesville Fl Raceway. Sixty foot times were 1.54

I ran 11.14, 11.15, 11.15, 11.16 in more 40 degree air up in Maryland @ MIR in December, 2011 with the pump. Sixty foot times were 1.56-1.57

I thought those GZ pumps were designed mostly for track use? If they have a version you can run on the street I would love to get one and ditch my breather caps and catch can!

I thought those GZ pumps were designed mostly for track use? If they have a version you can run on the street I would love to get one and ditch my breather caps and catch can!

They told me my pump would need to be rebuilt near 10,000 miles. That is 2-3 years street driving for me. I am on year 3 and probably 8k.

I didn't ask how much for the rebuild, but it is what it is. I am sure they are fair as they were great to work with getting my belt and brackets to work on a vehicle they don't actually make a direct fit kit for. Great company, Great pump !!

Pitt

What was your reasoning for putting a pump on in the first place? What difference(s) did it make for you? When you do send it in, would you mind letting us know what they charge to rebuild the thing?

What was your reasoning for putting a pump on in the first place? What difference(s) did it make for you? When you do send it in, would you mind letting us know what they charge to rebuild the thing?

I was having pressure issues at high rpm. It would blow oil out from the dip stick tube. The oil would spray over my header and cause a big puff of smoke on every shift while racing. The cause is probably from blowby from the rings, so I added the pump and now have no issues at all. It relieves all the crankcase pressure.

I was having pressure issues at high rpm. It would blow oil out from the dip stick tube. The oil would spray over my header and cause a big puff of smoke on every shift while racing. The cause is probably from blowby from the rings, so I added the pump and now have no issues at all. It relieves all the crankcase pressure.

Can I ask what the cost of such a setup might be? I have a 383 in my car, and while it seems fine I have the PCV hooked to the valley cover through a catch can, and I have a breather on each valve cover and I don't like it. I've been toying with the idea of putting one of these one.

Can I ask what the cost of such a setup might be? I have a 383 in my car, and while it seems fine I have the PCV hooked to the valley cover through a catch can, and I have a breather on each valve cover and I don't like it. I've been toying with the idea of putting one of these one.

They are near $800.

I have a 383 in my Z, and I get oil spray out of the breather on the valve cover so I bought a bag of black baby socks and double them up and slide over the breather. That catches about 90% of the oil spray.

http://i895.photobucket.com/albums/ac152/Pit-man/DSC05597.jpg

Pitt, did you ever find out what a rebuild would be?

Anyone sans Pittman using these having problems with oil fumes getting into the car?

Pitt, did you ever find out what a rebuild would be?

No I haven't checked. Should be able to shoot them an email from their site.


Anyone sans Pittman using these having problems with oil fumes getting into the car?

Mike, I think my problem with the fumes is the location of my vented catch can. It is back near the firewall. If I could find a location lower near the frame it shoud then vent under the cab.

Rebuilds run $100-$150 depending on what we find when we open it up. We always give you a call with our thoughjts on whether we should replace everything, or just the wipers and springs. It just depends on how much wear we see. It has a lot to do with whether the pump is getting sufficient oil to keep it lubricated.
The Z06 shop car has 17K on the pump. We looked at it at 15K, and it showed no wear, so we stuck it back in there. I ran a VP104 pump on our pump dyno for 500 hours and it only showed about .005 wear on the wipers, but it was run under great conditions.
I will start checking in here to answer vacuum pump questions, so fire away if you want my opinion on things.
Bill Huntington GZ Motorsports

Rebuilds run $100-$150 depending on what we find when we open it up. We always give you a call with our thoughjts on whether we should replace everything, or just the wipers and springs. It just depends on how much wear we see. It has a lot to do with whether the pump is getting sufficient oil to keep it lubricated.
The Z06 shop car has 17K on the pump. We looked at it at 15K, and it showed no wear, so we stuck it back in there. I ran a VP104 pump on our pump dyno for 500 hours and it only showed about .005 wear on the wipers, but it was run under great conditions.
I will start checking in here to answer vacuum pump questions, so fire away if you want my opinion on things.
Bill Huntington GZ Motorsports

Thanks for the info Bill. Great, high quality product.

Pitt

So Bill do a lot of LS daily drivers use these? I don't daily drive my car but its set up so I can drive it anywhere when I feel like it.

We sell a lot of LSX kits. Most of the kits we sell go on street cars. If you have a "undressed" LS motor, we can set it up to mount on the cylinder head like a SBC. We also have a drive mandrel specifically made for LS motors, so you can bolt it to your damnep and install any pulleys that you require.

I didn't like how the 22.5" belt, which came with the LSx kit, set the pump/inlet fitting so close to the coolant reservoir. After some searching, I found a 21" belt.

http://i27.photobucket.com/albums/c151/rlsracing/photobucket-35630-1339125716461.jpg



i have a GZ pump on my C5 vette and i need a new belt , would also like it a bit shorter, it´s rubbing the coolant reservoir

where can i get a belt, do you have any partnumber ...

thanks

Baezi

The standard belt we send out with a 46 tooth pulley is 22.5" long, 3/8" pitch, 1/2"wide. Gates "powergrip" part # 225L050. The 225 in the part# is the length, the 050 is the width.
I've bought similar belts from Grainger or McMaster-Carr. They are listed as "timing belts"
The best solution is usually a slightly shorter serpentine belt. It moves the tensioner over and creates room. For some reason, the clearance varies from car to car. We don't know if it is serentine belt stretchor what, but the 22.5" belt is usually the best one, but not always.