[steve25]

How much voltage is your charging system outputting when the fan is on?

[dv657172]

Voltmeter reads near 14

[SRGN]

A higher flowing fan would probably get temps under control while stationary and low speeds. With an iron headed, iron block engine, it takes a little more cooling to keep the temperature down. Some of the newer OEM fans have "trap doors" that open from airflow through the radiator at higher speeds when airflow exceeds what the fan can move, it's possible that higher CFM fans could help drop temps a couple of degrees during a pass.

[johnta1]

I'd try a different shroud than that one? One like the original style to funnel the air through? Also is the fan made to blow through or suck the air?
To me it looks like a restriction to air flow.

[dv657172]

Johntal its a Puller Fan

https://www.griffinrad.com/load_deta...p?key_id=PF-01

[AG]

I use a Mark VIII fan that has it's own shroud and works very well in keeping my car cool with a meziere water pump. My temps typically go up 10-15 degrees at the end of a quarter mile up to about 190-195 F. I also use a Griffin ali radiator.

[steve25]

I hate electric fans and agree with post 24.
These fans are mounted too close to the radiators due to the shroud’s being too shallow .

Look at it this way.
If the OEM shroud set up could have been made 3 to 4 inches shallower and still provide adequate cooling , then Pontiac would have gone for that savings in plastic of making a shroud.

Fan efficiency drops off pretty fast as a fan is moved closer to the radiator and since fans are round and radiators are rectangular a close mounted fan does not even pull any air through about 8 or so square inches of the average size radiator in a A body car.

[ta man]

Originally Posted by dv657172

Revisiting this issue...sort of

While it sounds like a 20-25 degree temp increase is normal on a run, I am still bothered by how fast the temp increases at idle even when its just idling in my shop or in the staging lanes. Temperature also doesnt begin to cool down until I get back to my pit after a run and shut it off leaving the fan and WP running.

What size CFM fan should I be running?
Current electric fan is a SPAL 16" rated at 1,918 True CFM which I bought from Griffin along with radiator & shroud (see pic) many years ago. A couple websites I read recommend 3,000+ CFM for 400+ engines.

Car has 461", 16 heads, Meziere Heavy Duty Electric WP, and I use a 5/8" water restrictor in place of a thermostat. Have only ever run distilled water and car is dedicated drag car.
Car also has a seperate B&M SuperCooler Trans cooler in front of radiator.

I run twin Spals rated at 4000cfm in a Derale Shroud with four relief flaps. Yours looks like a heat sink...not enough airflow and no flaps.

[dv657172]

Seeing a lot of positive comments on the Mark VIII fans.

I was wondering if the tightness of the shroud was an issue but I didnt realize a fan could be too close to a radiator, steve25.

AG/taman - possible to see a pic of your setup?

Thanks
DV

[steve25]

You need to check your water pump plate in the timing cover and in particular the rubber steel cased bushing behind it.
Many times new bushings are not tall enough to actually seal like they should on the rear side of this plate.

Placing a round shim spacer under the byshing will get rid of that leaky gap that should not be there.

In my photo here these washers used as spacers can be had from McMaster Carr supply.

I could not load the photo even after waiting 4 minutes, so here’s the part number for a pack of ten, 25237.

[AG]

Originally Posted by dv657172

Seeing a lot of positive comments on the Mark VIII fans.

I was wondering if the tightness of the shroud was an issue but I didnt realize a fan could be too close to a radiator, steve25.

AG/taman - possible to see a pic of your setup?

Thanks
DV

I'll try to get this weekend. Need someone to help take the hood off since it's under the lift.

[dv657172]

AG - thanks but if its too much trouble I understand

steve25 - car runs a Meziere Heavy Duty Electric WP so I dont think that is applicable (correct?) but good info for my other cars

[steve25]

I don’t know if that pump still requires the usage of that separator plate.

If you can see the pump veins then it would have to use the factory plate , and if that’s so then that pump vein to plate clearance needs to get checked and reset if it’s too great.

Ideally you do not want more then .025” pump vein to plate clearance needs.

Don’t forget that the front gasket adds clearance, so really the plate needs to be touching the veins with no gasket in place.

[AG]

Here are the pics of the Mark VIII fan. I use a 75 amp relay for it.

[ta man]

https://www.summitracing.com/parts/der-16927

This is what I have..will post a picture as well.

[dv657172]

AG & ta man - thanks for the pics and info, much appreciated!

[AG]

Super custom gold anodized wire separators for the shroud mounting up top.

[steve25]

What are you running running for a intake manifold?

[chuckies76ta]

Originally Posted by dv657172

Revisiting this issue...sort of

and I use a 5/8" water restrictor in place of a thermostat.

Get rid of that restrictor and install a 160 * Napa stainless thermostat. Have your fans running when engine is up to temperature. Remember that the thermostat will be fully open around the 160* to 165* mark. I also drill a 1/8" hole in the thermostat for a bypass.

[dv657172]

steve25 - Torker II

chuckies76a - why on the thermostat vs. water restrictor? How would that help any? Thermostat is basically only useful for warming up a cold engine quicker. Doesnt help in cooling one. Once its open its open and its not fully open until 10-15 degrees after the rating temp. At least thats my understanding

Fan and water pump can be controlled manually and are turned on as soon as car can idle on its own (generally about 125 degrees) plus I have a temp sensor that turns them on at 185 dgrees if I havent already for safetys sake.