Engine not coming up to temp

[joedoozer]

We are racing this Saturday so major swapping of parts or buying new stuff is not an option. Here is what I have.

Dirt Late Model. Iron head NLMS motor. Stock chevy water pump run 1:1. 6 blade fan behind a single pass radiator with a 32 lbs cap, with a nice fan shroud. I also have an adapter plate between the intake and the water neck, pulling water from the rear of the heads. During the summer I ran it without a thermostat and it always ran between 200 and 220. Never had a problem getting up to temp and staying there. Now that the weather has cooled off, it doesn't get warmer than 160-170.

Here are some options I have thought of. In what order would you rate them?

1. Run a restrictor under the adapter.

2. Run a thermostat under the adapter. It is not machined (yet) to run the thermostat on top. Summit tech line agrees that it would not pose an issue running it under the plate. It just won't heat up as fast as normal.

3. Remove the fan shroud

4. Make something to block part of the radiator off. Worried about it getting even more blocked with mud.

What other ideas would you come up with? Buying new pumps or pulleys or fans is not an option.

[sj valley dave]

We run a 19" 4 blade fan with a shroud and no restrictor/thermostat. We run a 15* reduction set up and just run tape on the radiator. We run it on the bottom as that is where most of the clay goes any way....We run 2-5 rows of tape to keep it at 200-210*...

[joedoozer]

I like the tape idea. It ran great all summer during 100+ degree ambient. Now that its in the 60's, I need to make a change.

[stock car driver]

stat works for me

My system runs so cool that a 3/16 hole like the racing stats have in them wont let my motor get to temp. So now I run a oem made in USA 195 stat with a 1/16 hole drilled in it to let the air out when filling.

My car runs on the stat opening and closing it, so it does its job unlike tape etc.

I have no holes in my nose and have the bottom 6 inches of my radiator taped off on the wire screen about a inch in front of it to keep ALL the dirt out so I dont have to pull and clean the radiator anymore.

jj

[sj valley dave]

We used thermosats in the past with good results, it's just our DLM engine builder is not a fan, he just thinks they're one more thing to have a potential problem with...

[JCSullivan00]

Ditto on the tape, that's how we do it too. Double the end over and leave three or four extra inches so it is easy to pull off.

[parrot69777]

I have run many of them at 170 degrees late in the year. Engines always seemed to have more power. Wish it would run that temp all year round.

[joedoozer]

Agreed. The more important indicator is oil temp, which should be at least 200* IMO. Other than that, I'd be tickled to death to have a motor run that cool.

Yeah its a good problem to have.

[powerslide]

so whats too cold?

[joedoozer]

I always thought that you had the risk of dry fouling the plug if the car idled and did not come up to temp. The plug wicking away too much heat from the tip because of the cold water temp. My opinion 170 is too cold. Especially at racing speed. Not sure if this is a "wives tale" or not. But I have seen a correlation between the two before. Not meaning that was the only cause for the fouling.

[sj valley dave]

We have a problem that if the engine is not up to 180* it will cr*p all over itself. We took out the NGK 9's that we ran in the summer and put in a set of 8's and really kept a sheet of cardboard over the radiator in the pits while it was idling waiting to go out to qualify and it did help. Went on the track at 180* and absolutely no misses till temp came up!!

[parrot69777]

I think it really all goes by each individual engine and the individual working on them. I have seen some that like 220 degree's and others that like 180 degrees. Reasons for this....some like an engine jetted rich and some lean. Some like more timing than others. Carb CFM? Compression? Etc.

Might not even be the engine at all. Could be the cooler temps were keeping the tires cooler and the driver thought it ran better because of getting more grip.

[sj valley dave]

On our deal, it didn't run bad, it crapped all over itself at 175* Just a solid miss for a couple of laps then ran fine...At 185* going on track, it's fine...I think the colder plugs might have contributed to the deal...

[stock car driver]

below 180 is too cold in my opinion

When I run a 350cfm carb all issues are magnified and 180 is the coldest my motors run really crisp at.

According to everything in print over the years 195 is optimum for hp


Im going to the chassis dyno tomorrow Ill pay attention a little better and see if my power is best first run or as we warm it up. I usually run it to warm up the rear, trans etc then do 2-3 runs where we never look at the numbers to get temp in it. We make sure its not super lean but thats it for those 3 runs. I can use those to see if it gains as it warms.

I think temp could also be really effected by if you have the right fuel etc. Too much octane will not burn well but maybe it will burn better hotter? Just a thought.

Im testing 110 and 100 tomorrow in my 10.5 to 1 360 with a 4412. As well as tuning in a new cam.

[parrot69777]

Just curious Jeff.....but does your dyno use the air temp from inside the shop or the air from outside?

[stock car driver]

TODAY... I did 3 pulls one at each temp on the way up. Usually I just run it until up to temp at a few grand spinning the wheel but this time I did actual runs to see the #s to post them here.

160 degrees
180 degrees
195 degrees

I gained 5-7 hp each run... period until it was running on the stat opening and closing for the duration of the day.

[joedoozer]

Ok so we are a little better after last night. I ran a 180 deg t-stat under the adapter plate. And I taped half the radiator. It still wouldn't come up to temp idling. Waiting to go out on the track I kept the RPM's up and the temp would climb slooooowly. Once racing the engine came up quick and stayed between 200 and 210. So I definitely can run a smaller radiator and fan, and I will get the adapter plate machined so I can run the t-stat above it.