Cooling system restrictor with hi volume pump

Lyn Smith · 06-26-2012, 07:09 AM

What size restrictor is used when changing to a high volume cooling pump like a mezarie?I ve got a 3/4 hole in place of the thermostat now,and it seems like the water runs through there pretty fast,and the engine is heating up faster.How small shoud i go?

Mike Taylor 3601 · 06-26-2012, 08:11 AM

Most of time I use thermostat w/center taken out,if it's heating up you may need bigger hole than you have now.
You may have to trial and era it a little till you get where you want.
Mike Taylor 3601

BlueOval Ralph · 06-26-2012, 08:20 AM

Small block Fords like a 5/8" for a start

Lyn Smith · 06-26-2012, 08:23 AM

that is what i have in there now is a 3/4 hole.Im thinking i need a smaller hole like5/8.If you take off the cap and watch the water in the radiator ,it is really pouring out of the tubes,where it just barely flowed out of them with the old heater style motor pump before.

Tom Goldman · 06-26-2012, 12:43 PM

When I switched from an old low volume Moroso pump to a Meziere 50 gpm pump ,I found reducing the restrictor from 3/4" to 1/2" was what the system wanted....Take a look at the actual area of an open thermostat, it isn't very much!
You definatly want to make sure the coolant stays in the radiator long enough.
Also a hi volume pump need an equally good cooling fan to go with it .
A good shroud and a fan with at least 1500cfm is worth a lot of cooling.

Gary Wiegand · 06-26-2012, 01:44 PM

Lyn,

What works for me on a 13+ comp. 383 sbc was to use a high flow 160 deg. thermostat with 2 or 3 small 1/8" holes drilled in the outside ring. The holes get the air out and allow for a nice "full" radiator. With more small holes or if the holes are too large like 7/32" or 1/4", the car takes too long to warm up in cool weather which is what happened if I tried to use essentially a washer with a hole in it. I also use a high flow aluminum radiator, a Meziere 35 gpm water pump and a 3,300 CFM Flex-a-lite fan which includes a shroud which is sealed to the radiator all the way around the shroud. The car basically runs what the thermostat is rated at even in hot weather. This allows me to go to the line with the SAME temp. each time. With back to back runs in 85-90 deg. air I might see 180 deg. water temp. This works for me, and eliminated trying to get the hole size "just right" with air temperatures all over the map.

1legjerry · 06-27-2012, 12:53 PM

If your engine is heating up you should take the restricted out, most drag racing application don’t need it. If you over heat you want more flow. If you are running to cool then you should add the restrictor. Also make sure all the air is out of the system could be a problem on Mopar engine as they are harder to get air out of. If you continue to have issues call Meziere’s, and ask for Greg or Jerry.

06-26-2012, 07:09 AM	#1
Lyn Smith VIP Member Join Date: Dec 2001 Location: Pontiac,il. Posts: 1,198 Likes: 282 Liked 963 Times in 193 Posts	Cooling system restrictor with hi volume pump What size restrictor is used when changing to a high volume cooling pump like a mezarie?I ve got a 3/4 hole in place of the thermostat now,and it seems like the water runs through there pretty fast,and the engine is heating up faster.How small shoud i go?

06-26-2012, 08:11 AM	#2
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,370 Likes: 350 Liked 297 Times in 102 Posts	Re: Cooling system restrictor with hi volume pump Most of time I use thermostat w/center taken out,if it's heating up you may need bigger hole than you have now. You may have to trial and era it a little till you get where you want. Mike Taylor 3601

06-26-2012, 08:20 AM	#3
BlueOval Ralph Banned Join Date: Feb 2008 Posts: 852 Likes: 0 Liked 0 Times in 0 Posts	Re: Cooling system restrictor with hi volume pump Small block Fords like a 5/8" for a start

06-26-2012, 08:23 AM	#4
Lyn Smith VIP Member Join Date: Dec 2001 Location: Pontiac,il. Posts: 1,198 Likes: 282 Liked 963 Times in 193 Posts	Re: Cooling system restrictor with hi volume pump that is what i have in there now is a 3/4 hole.Im thinking i need a smaller hole like5/8.If you take off the cap and watch the water in the radiator ,it is really pouring out of the tubes,where it just barely flowed out of them with the old heater style motor pump before.

06-26-2012, 12:43 PM	#5
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,474 Likes: 885 Liked 859 Times in 234 Posts	Re: Cooling system restrictor with hi volume pump When I switched from an old low volume Moroso pump to a Meziere 50 gpm pump ,I found reducing the restrictor from 3/4" to 1/2" was what the system wanted....Take a look at the actual area of an open thermostat, it isn't very much! You definatly want to make sure the coolant stays in the radiator long enough. Also a hi volume pump need an equally good cooling fan to go with it . A good shroud and a fan with at least 1500cfm is worth a lot of cooling. __________________ Tom Goldman 1500 SG , 1506 STK

06-26-2012, 01:44 PM	#6
Gary Wiegand Junior Member Join Date: Jun 2012 Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Cooling system restrictor with hi volume pump Lyn, What works for me on a 13+ comp. 383 sbc was to use a high flow 160 deg. thermostat with 2 or 3 small 1/8" holes drilled in the outside ring. The holes get the air out and allow for a nice "full" radiator. With more small holes or if the holes are too large like 7/32" or 1/4", the car takes too long to warm up in cool weather which is what happened if I tried to use essentially a washer with a hole in it. I also use a high flow aluminum radiator, a Meziere 35 gpm water pump and a 3,300 CFM Flex-a-lite fan which includes a shroud which is sealed to the radiator all the way around the shroud. The car basically runs what the thermostat is rated at even in hot weather. This allows me to go to the line with the SAME temp. each time. With back to back runs in 85-90 deg. air I might see 180 deg. water temp. This works for me, and eliminated trying to get the hole size "just right" with air temperatures all over the map.

06-27-2012, 12:53 PM	#7
1legjerry Junior Member Join Date: Jul 2011 Posts: 85 Likes: 4 Liked 72 Times in 15 Posts	Re: Cooling system restrictor with hi volume pump If your engine is heating up you should take the restricted out, most drag racing application don’t need it. If you over heat you want more flow. If you are running to cool then you should add the restrictor. Also make sure all the air is out of the system could be a problem on Mopar engine as they are harder to get air out of. If you continue to have issues call Meziere’s, and ask for Greg or Jerry.