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Author Topic:   Overheating
P5Racing
Member
posted September 18, 2002 10:07 AM
WE have started running hot. After we started running racing fuel. we ran pump gas up until 2 week ago. But we get out of the corners better now that we run racing gas.
I NEED HELP IN FIND THE PROBLEM. We have a big race in 2week 30 laps. An we can't run that long. with out getting hot.


KPLugnut
Member
posted September 18, 2002 01:21 PM
First, give us some more info on what you're running now as far as engine, timing, car class, etc, and any other info you can about the car (radiator, fan, shroud, etc). We'd need more info before being able to help.

Plenty of guys here will be more than happy to help you solve your problem for ya.

KPLugnut

P5Racing
Member
posted September 18, 2002 03:06 PM
17" flex-a-lite 6 blade fan ,time is 35 degrees advance,Chevy 355, streetstock class
2bbl carb.,22x19 radiator.

someone told me the timing chain may have stretch. we have 73 jet's in carb. i have 76 and was told i didn't have enough cam for it. it is 292 comp. cam.

outlawstock17
Member
posted September 18, 2002 04:05 PM
i'd quit listening to the "stretched timing chain" guy. LOL


justin
Member
posted September 18, 2002 04:56 PM
Are you running a restrictor or thermostat? What kind of water pump? How old is the radiator? Is it aluminum? Are you running a fan shroud? I run a 355, 36 deg. total timing, 180 deg. racing thermostat, 73 jets, 4 blade AFCO steel fan, and a stage 1 stewart water pump. I never get above 190-195 on the hottest nights. There are a lot of topics on overheating in this forum just do a search on it. Also, you can go to the stewart's water pump website www.stewartcomponents.com, they have a lot of good info there too. Good water pumps too. Good luck.

Justin

SLEEPY GOMEZ
Member
posted September 18, 2002 08:49 PM
I dropped 20 degrees when I switched from a generic aluminum 'racing' pump to a Howard Stewart, Stewart Components alum pump. A bit pricey for the low buck guy (about $170)but it might save a motor. It has the additional feature of its seal needs no lubrication. As per Chris Paulsen at C&R I use only distilled water, no additive.
SLEEPY


outlawstock17
Member
posted September 19, 2002 05:32 AM
another thing that no one has touched on yet is the radiator cap. if it started running hot all of the sudden, either something has gone wrong in your cooling system or you may have a cracked head or failed head gasket. i don't think the higher octane fuel has anything to do with it. are you losing coolant? if your radiator cap is bad, it will allow coolant through the overflow. sometimes you think it's losing coolant because it's overheating when in fact, it's overheating because it's losing coolant. make sure you have a racing radiator cap in the 28+ psi range.

sorry for the earlier reply....i just couldn't help myself!



rico 08
Member
posted September 19, 2002 12:51 PM
like justin said you need to be running a restrictor in the thermostat housing as a guideline if u run smog pulleys use one with the hole about the size if a dime if u use the older pulleys(big top and a smaller bottom)use one with the hole about the size of a quarter i use the hood plates that come with mr gasket hood pins just cut the outside to fit in the housing and cut you're hole in the center to you're style pulley's and pump speed


Scoot
Member
posted September 19, 2002 08:53 PM
I have to disagree with rico, DO NOT RUN A RESTRICTOR. its bad bad ju-ju

------------------
Scoot
Smith Racing Team
870-365-5989


justin
Member
posted September 20, 2002 03:25 PM
I agree w/ Scoot. The way I look at it is that you want to keep the water in the radiator as long as you can to give it a chance to cool down some. I know some people will disagree w/ me on that. Just my 2 pennies. Good luck racing.

justin

SLEEPY GOMEZ
Member
posted September 20, 2002 09:31 PM
The reason for the restrictor is to raise the water pressure in the cyl heads. This helps to eliminate steam pockets. Steam doesn't transfer heat well, therefore doesn't cool well.

The water doesn't move too fast in the radiator. Howard Stewart dynoed water pumps and cooling systems. The cooling system works better when the water flows faster. This is why he and others make high capacity pumps which flow more water.

Sorry, not trying to add fuel to the fire, but these are things I have found over the years.

Chris Paulsen at C&R Racing radiators did a bunch of tests on radiators and cooling systems. He says distilled water with NO additives is the best coolant. The half and half antifreeze many of us use raises the boiling point but it also raises the temp due to poor heat transfer. Also the Stewart pump has a seal which needs no lube. Hope this helps, SLEEPY

P5Racing
Member
posted September 22, 2002 12:23 PM
Thank for all the help. We hope we got it fixed with all the help we got from all of you.
Thank again
David


Monster
Member
posted September 22, 2002 03:40 PM
Sleepy, you are right on about the true purpose of a "restrictor". Very rare knowledge. It does not matter how 'fast' the coolant flows, as long as it does not boil! If it spends more time in the radiator to cool off, then it spends more time in the block to heat up, and vice versa. The pressurization is needed to reduce the chances of a steam pocket forming in the cavitation that can occur in a fluid passage filled with as many nooks and crannies as are in heads and blocks. The restrictor makes the head and block the place where most of the water pump pressure is expended, but may or may not reduce the flow. And imho, the more flow, the less likely a steam pocket.


justin
Member
posted September 22, 2002 08:08 PM
Wow, that makes pretty good sense. Thanks for that tidbit fellas. You learn something new everyday, huh. I think I'll try running a restrictor for a race and see how it does. I'll also try that distilled water trick too. Thanks again.

Justin

DirtDobber
Member
posted September 23, 2002 12:25 PM
WARNING ENGINEER AT WORK!!
LOL

To raise the boiling point of water you need to raise the “containment pressure.” When you do - consider the following excerpt from the steam tables. Remember at sea level the atmospheric pressure is 14.696 psi. Most of us live a bit higher than that. So our beginning boiling point is higher. But when the cap starts to seal you begin to raise the boiling point of water. The only additives that can help us are the ones that make water wetter. I know that is the name of one product of which I use but Joy dish soap does the same thing. Think about that one! That is the point at which water begins to boil. If the pressure in your system is say ten psi because of a faulty cap then the waters natural tendency is to boil at 193 degf. Keep the cooling system clean and free of scale and build up and it will work well for you. The restrictor works to do what the cap does raise the pressure. If the cap fails though….

Temp Abs
Fahr psi

198 11.058
200 11.526
204 12.512
208 13.568
212 14.696
216 15.901
220 17.186
224 18.556
228 20.015
232 21.567
236 23.216
240 24.968
244 26.826
248 28.796
252 30.883
256 33.091
260 35.427
264 37.894

So what does this mean? Run a higher pressure cap, keep in mind your equipment seals, alum vs. copper, rubber hoses, etc. This forces the water at the cylinder walls to pick up some temp and move on to the radiator so it can do its work - GET RID OF IT!!!


rico 08
Member
posted September 23, 2002 12:27 PM
definitely run a restrictor i think without one the coolant passes thru the radiator too fast to cool it down another thought if u are running a metric type car run the factory air dam below the radiator this will help get air into the rad instead of just going under the car i guess you can mount one on about any car


sanderson10
Member
posted October 02, 2002 09:24 PM
well my 2 cents i just take an old thermostat an cut the center out and use the outer ring for a restrictor not a whole lot of restriction but just enough works fine for me


Racer14K
Member
posted October 04, 2002 10:48 AM
I have always preferred a working 160o thermostat with 6, 1/8" holes drilled in the flange.


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