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2 4 0 T U R B O . C O M D A V E ' S V O L V O P A G E
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2 4 0 T U R B O . C O M D A V E ' S V O L V O P A G E
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page is being developed to explore and preserve some valuable
information related to high performance engine cooling for our Volvo B21, B23 and B230 engines. If you can help or if you have a comment, please email. CONTACT |
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| Coolant Bypass Valve Info |
Red Block Coolant Map |
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| Group A 240 Cylinder Head Cooling Holes |
Group A 240T Owner's Manual |
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| SCP Head vs BCP head |
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| This page will not be repeating information I have in other pages concerning cooling fans or fan controllers, which can be found at the below links. | ||
| Volvo Electric Cooling Fan Page | Brushless Cooling Fan Page | |
| Adding a COOLANT BYPASS VALVE This will discuss adding a 4-port coolant bypass valve to the heater hose circuit. I have a 240, so please forgive me if most of my info tilts toward that model, however, there is also plenty of info here for 700-900 models. Reasoning for adding such a valve can be found below where the Coolant Map is explained, in addition to the TB discussion below. This first valve shown below has a VACUUM DIAPHRAGM to cycle it ON or OFF. If vacuum is present the valve will close. This type of valve is discussed in the following Turbobricks discussion. https://turbobricks.com/index.php?threads/7-9-updated-heater-control-valve.246617/.   The above vacuum type valve was shown in the linked Turbobricks discussion because it was adapted to worked in a vacuum actuated 700 system. This type of valve may or may not be appropriate for a 240. You'll have to make that decision if you feel that a vacuum controlled valve is right for your car. PART QUALITY NOTE: Having a quality, leak free valve is super important. A leaky one will not be worth the trouble if it saved you a few dollars. The above TB discussion found some cheap valves that people discovered would begin leaking eventually. Other bypass valve types. You can also find manual Cable actuated valves or electric valves. The electric valve below is from CJ Pony Parts. This one can be opened or closed (or partially opened) using a variable knob.  This one is available at https://www.cjponyparts.com/heater-bypass-valve-kit-servo-controlled-bronco/p/BHV4/ Restomod Air has a similar 4-port valve: https://restomodair.com/shopproducts/4-way-electronic-bypass-water-valve-kit/ Typical 4-port bypass valve diagram.  To Bypass or Not to Bypass. The below coolant maps should help with our understanding of coolant flow. In the below map, Location #1 shows the first entry of coolant from the radiator into the water pump. Location #5 shows coolant exiting the cylinder head and going to the firewall. In a 240 the coolant flowing through the firewall will be interrupted by a heater valve, which is controlled by a cable. When this factory valve it set to COLD, the heater valve will always be closed. This closed position means no hot coolant will circulate out of the back of the cylinder head, through the heater core and then back to the water pump. The general thought is that by allowing this coolant circulation to bypass the heater valve and core, we can potentially improve cooling, particularly in the rear cylinder head region where the cylinder head can be known for being hotter. TB discussions have reported real world improvements using a bypass valve (more relevant links below).   Relevant Links: https://turbobricks.com/index.php?threads/7-9-updated-heater-control-valve.246617/ https://turbobricks.com/index.php?threads/8v-b230-cooling-system-modification.121189/ Relevant General Cooling System Information Cooling System Basics: https://www.c1pulleys.com/pages/cooling-system-basics The Cooling Bible: http://www.billavista.com/tech/Articles/Cooling_Bible/index.html GROUP A Cylinder Head Cooling Holes This cylinder head modification has been around for a long time, but it has not been widely known or widely understood (outside of Sweden at least). Most explanations (including the below video) discuss using a head gasket to determine the locations of the FIVE new cooling holes to be added (with three holes added along the EXHAUST SIDE).  The hole sizes shown above may not be what everyone expects. I took them from the BELOW VIDEO. One of the mysterious questions that came up in my mind after studying this is as follows: This concerns the three holes along the long edge. Some of the old 240 Turbo Group A references and images clearly show these three holes are drilled on the INTAKE side, not the EXHAUST side as seen above, however virtually all other images, including more recent ones (like ABOVE), show these holes drilled on the EXHAUST side. Putting holes along the INTAKE side will be more difficult, because it does not appear any head gaskets have those holes on that side to use for a pattern. For example, this one BELOW is posted in https://240grupp-a.se/kylning/ with holes drilled on the INTAKE side.  If I was to offer an uneducated opinion, I would choose to make these holes on the hotter EXHAUST side. I welcome your comments. This short VIDEO below offers a welcomed explanation of how these holes are added. Group A 240T Head Cooling Mod. https://www.youtube.com/shorts/qqn_xvRclG0
https://turbobricks.com/index.php?threads/8v-b230-cooling-system-modification.121189/ https://ozvolvo.org/d/9617-530-531-head-porting-and-polishing/19 https://www.stonis-world.com/headwork.html https://turbobricks.com/index.php?threads/are-people-still-doing-the-grpa-cooling-mod.382897/ This image below has been around for a long time. It's from Bilsport Magazine Nr 10, 2001, page 27 (in Swedish). It very lightly discusses adding the Group A 240T cooling holes. An English interpretation is below.
This is Page 14 from the Volvo 240T Group-A Owner's Manual, by Richard Prince.  Note that this image also has the three long edge holes drilled on the INTAKE side. This cylinder head image above came from https://240grupp-a.se/kylning/. The above page also mentions that Group A heads were further modified by blocking off the water pump port by inserting a "welch" plug (same as a freeze plug).  The complete 32 page PDF MANUAL can be found at https://1drv.ms/b/s%21AtjXfjFx5NHNjakt9r9kaL2_GeVI9Q  BCP versus SCP heads Here you can see the difference between a BIG COOLANT PASSAGE (BCP) head and the more desirable SMALL COOLANT PASSAGE (SCP) head.  Why is the Small Coolant Passage head considered better? It's considered to be a stronger design, sealing better at the head gasket when under high stress or high boost, and potentially less prone to cracking. When did this change occur? One Turbobricks member wrote: "I have a 398 head BCP dated 3/3/84... and a 398 head SCP dated 4/12/84." I also have a 398 SCP head I pulled from a Pick-A-Part that is dated 4/4/84. Apparently this change occurred between March 3 and April 4, 1984. Where can you find the date code? It's molded into the aluminum on the exhaust port side very close to the back of the head. The numbers are vertical (Day - Month - Year), i.e.: for a 12 April 1984 head the numbers appear as 12 on top then 4 then 84 on bottom. This example below is a 160 head with a date of 23/4/83 (23 April 1983).  |
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