Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Race Car Tech
Reload this Page >

FC engine issues while autocrossing in hot weather

Race Car Tech Discuss anything related to road racing and auto X.

FC engine issues while autocrossing in hot weather

Old 06-05-06, 10:10 AM
  #1  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
Exclamation FC engine issues while autocrossing in hot weather

So I took the now E-Stock GTUs (we were running STS2) to a local BMWCCA open practice on a 100+ second fast course, several 3rd gear sections, but a good mix to technical elements and good flow.

First off, the car was amazing. We were running EASILY the top 5 raw times of all of the cars/drivers there, including instructors. As I was on street tires, I was trying to get comparisons from other street-tire'd cars also, but we still ended up faster. Just a testament to the great inherant balance of the FC...very controllable and consistent, probably more so than when the car was in hair-trigger mode in STS2. The cheap KYB AGX's did their job, and after doing some testing settled on the #4 setting up front (full stiff) and #5 or #6 out back (3/4 up from full soft), Eibach big front bar and stock rear, stock springs/mounts, no camber up front.

It was in the mid 90's down at the stadium, and most everyone (not only myself) could only do a lap or two back to back before having to take a cool-down break, as the cars (and tires) were running hot. My GTUs still has the Mazda Competition main and alternator pullies, as I have not had a moment to change them out, as well as the stock fan and stock radiator and 16lb cap. The temp gauge was always near or at the middle of its sweep, just like on the street, but towards the end of my second lap in a row the temp would climb to about 3/4 up.....immediately I would drive around and rev the motor to help the water pump move coolant through the engine, which would bring the temps down to about normal within a minute or three.

The problem lies when I would pull off and just hold the rpm's at 2-3K to move coolant, that the engine would weep oil as well...not when it was "normal temp", but only when it was getting hotter. As soon as the temps cooled, it would stop weeping oil. It appeared to be from between the housings, as I checked the cooler lines, oil filter, sensors, and the other usual suspects. This isn't an English car, and my 12A and GSL-SE have never done this, so I thought it unusual. Not dumping oil, but weeping and dripping a few thimble-fulls from a few places.

Suggestions? I know that when the stock pullies go back on, my idle cooling will be improved (as the pump will spin faster). Also, while the engine only has 4200 miles on it, the coolant does not look "clean", and I was worried that there may have been an o-ring leak or something else, but testing of the coolant shows that there is no oil present. I also do not get bubbling or gasses in the coolant.

I will probably also drain/flush the cooling system and make sure there is no air in there. I have also been told that too much timing advance can cause an engine to run warmer, I believe we are running too advanced (can't get a consistent timing reading, even with the stock NGK wires).

Alright, sorry for the long post, it's been a while since I've run the car :-)

-JW
DaveTurnerMotorsports is offline  
Old 06-05-06, 10:48 AM
  #2  
Kim
OBEY YOUR MAZDA
 
Kim's Avatar
 
Join Date: Oct 2002
Location: Denmark
Posts: 3,059
Likes: 0
Received 0 Likes on 0 Posts
First make sure that the incoming air cant escape the radiator, shroud and cap off any holes inthere.
According to Mazda, the stock waterpump has no pumping effect at constant high rpm's
You can reduce the rpm on the waterpump by using a larger pulley.
The one i'm using is 130mm in diameter.
http://www.wankelkim.net/rx7/fb/waterpulley.JPG
You're right too much timing will make it run hotter.
Get a watertemperatur gauge, the stock instruments really only tells you if your screwed or not
Try Water-Wetter or a similar product, racing rotaries needs all the cooling they can get, dual oilcoolers is another option.

Last edited by Kim; 06-05-06 at 10:55 AM.
Kim is offline  
Old 06-05-06, 11:41 AM
  #3  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
Thanks,

Already using Water Wetter. As the car is required to run in a Stock class, alternate pullies are not allowed--- they are only on the car now because we have yet to do all the final Stock parts installs after coming off of a class that allows a higher level of preparation. We may not alter or modify the radiator, fan, shroud, or any part of the cooling system. We can only add an electric fan during ProSolo series events, but then put the stock mechanical fan back on for National Tour events (SCCA Enterprises controls ProSolo, SCCA sanctioning body controls regular Solo2 events).

-JW
DaveTurnerMotorsports is offline  
Old 06-05-06, 01:00 PM
  #4  
Junior Member
10 Year Member
 
Join Date: Mar 2001
Location: San Diego
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Are you still running the stock Thermostat. If so, and the rules allow, remove and Gut it so you keep the size of the hole about 3/4" and make sure bypass at the bottom is plugged. Also I would look at the area between the front ai inlet and the radiator is clear. Try and clean up this air flow area so you can maximize the air flow to the radiator. Stupid question are you still running the stock radiator shroud.
ItsRotary7 is offline  
Old 06-05-06, 01:18 PM
  #5  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
Stock thermostat and stock fan shroud, also frontal area is clear....the A/C has been removed, so no condenser to get in the way. Fan clutch is also functional.

I may need to replace the radiator anyway (it is new, but shows some wetness on the seam of the tank, seems to be split but not weeping, just leaving very trace residue...no leaks up top (return hose, cap, etc.).

Another issue may be that the lower tray has been removed-- we pulled it to do continuous engine work, and then it was burned up in the PureSports fire, so I have not had the chance to find a replacement. Could I not have enough pressure behind the radiator?

-JW

-JW
DaveTurnerMotorsports is offline  
Old 06-05-06, 04:45 PM
  #6  
Lives on the Forum
15 Year Member
 
DamonB's Avatar
 
Join Date: Feb 2001
Location: Dallas
Posts: 9,617
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DaveTurnerMotorsports
Another issue may be that the lower tray has been removed
If that tray forms the bottom of the radiator duct as it does on the FD then that's your problem right there.
DamonB is offline  
Old 06-05-06, 05:51 PM
  #7  
Junior Member
10 Year Member
 
Join Date: Mar 2001
Location: San Diego
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Yes, if the lower panel is not there, all air entering the grill area will go out directly under the radiator and not thru it. Blew a motor up before we realized that mistake The air will take the path of least resistance, which when no panel straight under the car. That is also why we try to see all area's of the radiator support so that all air exits via the radaitor. When you install it make sure that it seals to the bottom of the Oil cooler as again the air will pass right under it.
ItsRotary7 is offline  
Old 06-05-06, 07:04 PM
  #8  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
Anyone have the stock Mazda part number for a new one that will fit at S5?

-JW
DaveTurnerMotorsports is offline  
Old 06-05-06, 11:09 PM
  #9  
10 lb. boost, 5lb. bag
10 Year Member
iTrader: (1)
 
Gene's Avatar
 
Join Date: Mar 2001
Location: New York, NY
Posts: 1,076
Likes: 0
Received 0 Likes on 0 Posts
Yup, that panel is super important. I got to a track event without one once and the temps made me real nervous. Went to home depot and bought some plastic signs, cut them up and ziptied them, knocked the temps down 10 degrees.

You definately should get a proper water and oil temp gauge set. The stock temp gauge only has three positions: cold, warm, and new engine.

If you're allowed a different radiator, get a nice big aluminum one.
Gene is offline  
Old 06-06-06, 03:55 AM
  #10  
Kim
OBEY YOUR MAZDA
 
Kim's Avatar
 
Join Date: Oct 2002
Location: Denmark
Posts: 3,059
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DaveTurnerMotorsports
Anyone have the stock Mazda part number for a new one that will fit at S5?

-JW
FB01-56-111C
Kim is offline  
Old 06-06-06, 09:03 AM
  #11  
Full Member
10 Year Member
 
carsaregood's Avatar
 
Join Date: Aug 2003
Location: Huntington Beach
Posts: 115
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DaveTurnerMotorsports
Stock thermostat and stock fan shroud, also frontal area is clear....the A/C has been removed, so no condenser to get in the way. Fan clutch is also functional.

-JW
james - this is off topic, but doesn't that A/C removal take you out of stock class? or is it ok because there are other 2nd gen NAs that came without it?
carsaregood is offline  
Old 06-06-06, 09:48 AM
  #12  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,578
Likes: 0
Received 123 Likes on 112 Posts
Originally Posted by Kim
FB01-56-111C
beat me to it!
j9fd3s is offline  
Old 06-06-06, 10:44 AM
  #13  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
The GTUs only came with a dealer-installed A/C system, according to Mazda literature. As it is a dealer-installed option, and other GTUs could be ordered without it, I can legally backdate the option package. Same with the rear seats, should I have the need to get rid of 40lbs quickly and install the cloth storage bins :-)

There is also verbage about "comfort and convenience", so that even though the GTUs never came with cruise control, I could probably legally add it and not get protested.

Basically, you can delete or add options if they were originally orderable individually, or you can basically "build you own".

Like if you had a '99 Miata you wanted to run in C-Stock, but you had the Base model with 14" wheels, A/C, and power windows, you could convert to the Sport version (or Club Sport) by installing crank windows, removing the A/C, and moving up to the 15" wheels as long as you did the complete package.

Technically I guess you could build your own GTUs, if the base models came with no sunroof....hood, trans, rear end/VLSD, door panels, seats, chassis reinforcement, brakes, 16" wheels, and whatever else it came with, as long as you could document it from Mazda.
DaveTurnerMotorsports is offline  
Old 06-06-06, 10:51 AM
  #14  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
FB01-56-111C = $108.20 +s/h from Mazda Competition, yikes! Time to go junkyard shopping......unless someone in San Diego/Orange County/Riverside County has one :-)
DaveTurnerMotorsports is offline  
Old 06-06-06, 11:58 AM
  #15  
Lives on the Forum
15 Year Member
 
DamonB's Avatar
 
Join Date: Feb 2001
Location: Dallas
Posts: 9,617
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by DaveTurnerMotorsports
As it is a dealer-installed option, and other GTUs could be ordered without it, I can legally backdate the option package.
You mean delete the option package? You cannot update or backdate in any stock class. You can add or remove entire option packages from the same model year if the car was originally available from the dealer that way, but you cannot ever update and backdate in stock by mixing and matching parts from different model years.
DamonB is offline  
Old 06-06-06, 01:34 PM
  #16  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
DamonB-

Correct, I meant add or delete.......non-SCCA folk understand the "UD/BD" differently than we do, that is why I worded it that way.

UD/BD is only okay in SP or higher classes, adding and deleting within options are okay in Stock and ST classes.

-JW
DaveTurnerMotorsports is offline  
Old 06-06-06, 07:19 PM
  #17  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
Just ordered a new undertray from Mazda Competition (muttering under breath)......hope it arrives before the next autocross up at Fontana this coming Sunday!


-JW
DaveTurnerMotorsports is offline  
Old 06-07-06, 05:11 PM
  #18  
Drive it like ya stole it
5 Year Member
 
Slo Motorsports's Avatar
 
Join Date: Feb 2006
Location: Mass
Posts: 380
Likes: 0
Received 0 Likes on 0 Posts
Good luck with the "stock" setup James. We're giving our AE its first official outing this weekend at the Tire Rack National at Devens. Looks like rain for Saturday and mild temps for Sunday so we'll luck out not having to worry about over-heating (just everything else). What "water wetter"? I'll have to search on it.
Slo Motorsports is offline  
Old 06-09-06, 09:28 AM
  #19  
Full Member
5 Year Member
Thread Starter
 
DaveTurnerMotorsports's Avatar
 
Join Date: Oct 2005
Location: San Diego, CA
Posts: 169
Likes: 0
Received 0 Likes on 0 Posts
Good luck Slo_Motorsports! Are you running ASP, or SM2? We'll be at Denver (Tour and Pro) and Wendover (Pro) before Nationals in Kansas, I may just run STS2 to finish up the season in one class, run STS2 at the ProSolo Finale, and then depending on how I do run E-Stock at the Solo2 National Championship. It's been a few years since I've been, I'm kind of excited!

Do a search for Red Line Water Wetter, or Royal Purple Purple Ice. We have also had very very good luck with ProBlend's 40-Below product, but it is a little more involved than just pouring a small bottle in-- but with better results!

Installed the stock Mazda undertray last night, temps coming home on the freeway were a tick UNDER 1/2 on the gauge, while usually it is a tick OVER 1/2. I'll bleed the system before Sunday and see if it helps as well.

-JW
DaveTurnerMotorsports is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
dkwasherexd
Single Turbo RX-7's
21
05-27-17 04:51 AM
IB Cristina
West RX-7 Forum
0
08-20-15 05:46 PM
gtcd
1st Generation Specific (1979-1985)
30
08-19-15 02:44 AM
rx7jocke
Single Turbo RX-7's
1
08-15-15 03:36 PM
befarrer
2nd Generation Specific (1986-1992)
4
08-14-15 04:18 PM


Thread Tools
Search this Thread
Quick Reply: FC engine issues while autocrossing in hot weather


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: