Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute) - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 02-27-2014, 12:13 PM   #1
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,010
Total Cats: 583
Default Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)

This is an outgrowth of Concealer404's thread on overcooling with a BEGI "Racer" reroute. As part of that thread, I got on Visio and drew up some cooling diagrams. They present the whole reroute issue so clearly that I thought they were worth posting for general interest. As they say, a picture is worth a thousand words.

First, let's start with the OEM coolant routing:



Mazda's dilemna was fitting a FWD transverse engine to a RWD chassis. To preserve maintainability, they wanted the thermostat in the front. They had room to fit a large radiator, so why not?

Note that with the OEM configuration, the most even flow of water through the engine is with the thermostat closed. As the thermostat opens, the path of least resistance to get out of the engine/head moves towards the front cylinders which tends to starve the rear cylinders of cooling. Not ideal.

In addition, it means that the radiator never sees full flow no matter how open the thermostat is because some coolant always takes the path through the heater core. That means radiator efficiency is also compromised -- which is one reason our radiator is more than twice as large as a Civic's.

So, the Mazda engineers paid a heavy price for that front thermostat. But they weren't dumb. They sized the components so that the engine retained adequate cooling water (at OEM power levels) with the thermostat fully open in hot conditions.

Alas, who among us is happy at OEM power levels? #4 gets awfully hot when you bump it up. Hence . . . the traditional reroute:



Since we're men and don't fear blood on our knuckles, the traditional and best way to reroute is to restore the flow of coolant to the FWD transverse configuration. This is really the optimum configuration. Every bit of water goes through the entire engine from front to back cooling every cylinder. Doesn't get much simpler or effective than this. On my cars, I do this with a BEGI spacer, KIA waterneck, GM truck hose and TSE waterneck block-off. BAM!! (Relatively cheap too).

The above seems so obvious. So, what might be this BEGI "Racer" reroute I'm reading about? Went to BEGI's website to check it out. Aaaannnddd . . . here it is in all it's glory:



In this setup, all water always goes through the radiator with some of it going through the heater core as well. So, expect LOOOONNNNGGG warmup times (under some conditions you may never warm up). Plus, the deficiency with water balance through the engine remains. WAIT!!! Actually . . . it's worse!!! How can that be?

Look carefully. The highest pressure point in the system is the water pump outlet. Likewise the lowest pressure point in the system is the water pump inlet. The water pump belt provides the mechanical power to make this happen. Now, with the OEM system the flow through the rearmost cylinders is:
1. pump outlet
2. rear cylinders
3. heater core
4. pump inlet

But, with this system, the flow is:
1. pump outlet
2. rear cylinders
3. heater core
4. radiator
5. pump inlet

The benefits of this system is that it increases water flow through the radiator and doesn't mix water from the heater core (which may not have been cooled) into the water pump inlet. Only the radiator feeds the water pump inlet. But it doesn't fix the cooling balance problem and may make it worse. And, of course, it may never warm up. Not good.

Some recommend "fixing" this reroute by moving the T into the lower hose. Here's what that looks like:



Bears an uncanny resemblance to the OEM system, doesn't it? LOL. At least it's better than a T in the top hose.

TL;DR . . . if bumping power, install a traditional reroute. Avoid the BEGI racer reroute.
Attached Thumbnails
Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)-begi-bottom.png   Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)-begi-top.png   Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)-oem-cooling.png  

Last edited by hornetball; 02-27-2014 at 03:01 PM. Reason: Correct diagrams/writeup based upon Brainy input
hornetball is offline   Reply With Quote
Old 02-27-2014, 12:14 PM   #2
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,196
Total Cats: 2,583
Default

Propped for truth. This is sticky-worthy
18psi is offline   Reply With Quote
Old 02-27-2014, 12:16 PM   #3
Senior Member
iTrader: (2)
 
Join Date: May 2010
Location: Beckley, WV
Posts: 868
Total Cats: 36
Default

I hear the hyper reroute is the best.
Tekel is offline   Reply With Quote
Old 02-27-2014, 12:30 PM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,892
Total Cats: 1,792
Default

I think your diagrams for the begi "reroutes" are incorrect. but im too lazy to actually bother.
Braineack is offline   Reply With Quote
Old 02-27-2014, 12:34 PM   #5
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,107
Total Cats: 518
Default

It's a little more complicated than this, but yeah, pretty much right.

It does fail to distinguish between thermostat open routing and thermostat closed routing, and where it routes through the block.

For instance, in the OEM routing, it doesn't accurately show how the water doesn't go through the block when warm, instead mostly going right back out the front neck.





Basically I like the colored pictures.
Attached Thumbnails
Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)-miata_coolant_route_stock.jpg   Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)-miata_coolant_reroute_schematic_web.jpg  
curly is offline   Reply With Quote
Old 02-27-2014, 12:43 PM   #6
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,010
Total Cats: 583
Default

NVM.

Last edited by hornetball; 02-27-2014 at 02:51 PM. Reason: Deleted based upon corrected main write-up
hornetball is offline   Reply With Quote
Old 02-27-2014, 12:44 PM   #7
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,010
Total Cats: 583
Default

NVM

Last edited by hornetball; 02-27-2014 at 02:51 PM. Reason: Deleted based upon corrected main writeup
hornetball is offline   Reply With Quote
Old 02-27-2014, 12:44 PM   #8
Elite Member
 
DNMakinson's Avatar
 
Join Date: Jan 2013
Location: Seneca, SC
Posts: 2,704
Total Cats: 269
Default

And what changed with the '99 and the different openings in the head gasket?
DNMakinson is offline   Reply With Quote
Old 02-27-2014, 12:56 PM   #9
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,010
Total Cats: 583
Default

From 2001 onward, the OEM head gasket restricted flow to the front of the cylinder head to force more water to the rear. This amounts to "water balancing." Definitely beneficial at OEM power levels. May not be enough at elevated power levels.

949 recommends changing to an earlier headgasket if a traditional reroute is installed.

Last edited by hornetball; 02-27-2014 at 02:55 PM. Reason: Correct response based upon main writeup corrections
hornetball is offline   Reply With Quote
Old 02-27-2014, 12:59 PM   #10
Elite Member
 
DNMakinson's Avatar
 
Join Date: Jan 2013
Location: Seneca, SC
Posts: 2,704
Total Cats: 269
Default

Sorry to potentially mislead. According to TSE, it was 2001, rather than 1999. I think I will do a little research.
DNMakinson is offline   Reply With Quote
Old 02-27-2014, 01:37 PM   #11
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,107
Total Cats: 518
Default

Good, a confusing thread like all the others. My job here is done.
curly is offline   Reply With Quote
Old 02-27-2014, 01:39 PM   #12
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,892
Total Cats: 1,792
Default

Quote:
Originally Posted by hornetball View Post
I wish. I was shocked.
But they aren't correct how you drew them.

I think these more accurate represent them:




The Rear Thermostat reroute they sell, is the exact same thing as the typical reroute diagram you posted with the additon of the water bypass, which is silly.
Attached Thumbnails
Why You NEED a Reroute (and why it should NOT be a BEGI racer reroute)-begireroutes.jpg  
Braineack is offline   Reply With Quote
Old 02-27-2014, 02:01 PM   #13
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,010
Total Cats: 583
Default

Yeah, those diagrams are better. Shows how water goes into the block and out from the head. Main writeup has been corrected to show this important detail. Thanks.

Last edited by hornetball; 02-27-2014 at 07:54 PM.
hornetball is offline   Reply With Quote
Old 02-27-2014, 02:36 PM   #14
Elite Member
 
codrus's Avatar
 
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 3,878
Total Cats: 344
Default

Quote:
Originally Posted by DNMakinson View Post
Sorry to potentially mislead. According to TSE, it was 2001, rather than 1999. I think I will do a little research.
Yes, it was 2001. 99/00 have the same head gasket as 94-97.

You don't want to run a traditional reroute with an 01+ head gasket.

--Ian
codrus is offline   Reply With Quote
Old 02-27-2014, 02:41 PM   #15
Elite Member
iTrader: (1)
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 4,685
Total Cats: 216
Default

Hey guys, what if you did a reroute with the thermostat on the back of the head, but also left the thermostat/housing in the stock location!? Then plumb them together into the radiator.

It would be like double the cooling.

A true revolutionary innovation! Dare I call it The Holy Grail of reroutes!?
Full_Tilt_Boogie is offline   Reply With Quote
Old 02-27-2014, 02:43 PM   #16
Elite Member
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

I'm still confused on the consensus on 01+ and a reroute...haha. I was running the reroute awhile back, but took it off when HG design was discovered and it was understood that it was a "bad" idea. That was also when livin in the hot n' humid Southeast. Now that I'm in the much cooler and dryer PNW, I feel the stock setup with the standard large radiator should be good.
Doppelgänger is offline   Reply With Quote
Old 02-27-2014, 02:51 PM   #17
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,892
Total Cats: 1,792
Default

Quote:
Originally Posted by Full_Tilt_Boogie View Post
Hey guys, what if you did a reroute with the thermostat on the back of the head, but also left the thermostat/housing in the stock location!? Then plumb them together into the radiator.

It would be like double the cooling.

A true revolutionary innovation! Dare I call it The Holy Grail of reroutes!?

BEGi actually suggested that for a while. I think using two temperature stats.
Braineack is offline   Reply With Quote
Old 02-27-2014, 03:10 PM   #18
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,367
Total Cats: 1,331
Default

Quote:
Originally Posted by Doppelgänger View Post
I'm still confused on the consensus on 01+ and a reroute...haha. I was running the reroute awhile back, but took it off when HG design was discovered and it was understood that it was a "bad" idea. That was also when livin in the hot n' humid Southeast. Now that I'm in the much cooler and dryer PNW, I feel the stock setup with the standard large radiator should be good.
Haven't you had your motor open twice now? Why are you still running an '01 head gasket?
Savington is offline   Reply With Quote
Old 02-27-2014, 03:19 PM   #19
Elite Member
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

Engine #1 was a swap with a stock engine, not rebuild. This time I'm hopefully buying an assembeled "budget" built engine....dunno which HG was used...will ask though.

Last edited by Doppelgänger; 02-27-2014 at 04:56 PM.
Doppelgänger is offline   Reply With Quote
Old 02-27-2014, 03:22 PM   #20
Elite Member
Thread Starter
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,010
Total Cats: 583
Default

Fixed the main writeup based upon Brainy's comments.
hornetball is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 Yesterday 09:00 PM
Complete BEGI S3 NB Kit, Full Enthuza 3" Exhaust, ACT HD Clutch, MS2 PNP, Wideband kronikker Miata parts for sale/trade 17 10-06-2015 11:18 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:36 AM.