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Any way to bump up my RPMs when fan comes on?

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I didn't mention what the engineer has advised, because I do NOT want you to lose an alternator.

If you unhook an alternator output when the engine is running there is great probability that you will ruin the alternator.


This used to be an old test, way back in the 60's was to unplug the alternator with the engine running and if it kept running the battery was ok. That test was even taught in Italian dealerships (Fiat, AlfaRomeo,Ferrari)..
Then the cars that had that test done would have their alternators die, some right away, some not for several months.

You are putting a "spike" type situation in the charging system when you unplug it running. Newer alternators should, key word is should, withstand the spike, but any older alternator is at a strong risk of going kaput in the near future.

So I strongly advise against disconnecting the alternator power when the engine is running...
 
RonMacPherson said:
So I strongly advise against disconnecting the alternator power when the engine is running...
Click to expand...
:iagree:
However, there is no danger in disconnecting the alternator with the engine stopped, and then starting the engine with it still disconnected.
 
Here's my 2 cents worth,
First- fans- not all created equal. many companies make different FLOW capability in the SAME size. ie 1500 cfm up to 3650cfm (some that i have seen).
Higher flow-better cooling. The hp to run the fan is proportional to the FLOW.(more or less) just because it is 16" doesn't necessarily mean it is high flow.

AS the hp required goes up, the load on the alternator goes up. As the load on the alternator goes up, the hp to drive it goes up. If you have a huge alternator, the hp to drive it at idle is higher than a small alternator.
So, if you put in a really big alternator, you will use more hp to drive it all the time but when the fan comes on, it will have less impact on the draw. You will have re-set your idle to accomodate the bigger alternator but the fan will have less affect on the hp to drive the alternator.

A bigger alternator that has a very large amperage capability at idle will cost you HP, ALL THE TIME. That's why you see really tiny alternators in race cars.

SO, to solve the rpm problem at idle, you could go to a lower flow fan that would be on more often or on all the time and re-set the idle with the fan on.

Personally, i would take the choke cable and use it for a high speed idle instead and leave the fan alone, especially since it is a "hot" motor.

For a tr4 with 10:1 compression and all the hp goodies, I have been told to never go over 70 degrees celcius (158 gerees fahrenheit).So i have a 3500 cfm fan to ensure i never get too hot.

R
 
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