I see your point now, thanks for clarifying. And yes, I agree with you now.

Don
Which fans were you running?

As pointed out already the stock fans and belts draw about a tenth on small blocks - and back in the 70’s it was common on a few cars to purposely misalign the alternator so in a burnout you would blow the belt off, effectively running down the track without the belt.

Usually done on class racers or when running a tight race against a similar class car in the eliminator.

Back then the rules said everything had to be stock and hooked up. Rules didn’t say they had to stay hooked up - another “read between the lines” interpretation.

Electric fan= Derale..... nice unit......Moroso billet water pump

Stock was stock production fan setup and waterpump

Thanks.

I have the MP viscous fan kit on my Dart and am curious if there was enough gain to justify the cost to change over. My deal is street/strip so if I changed it would have to work on the street too.

I changed too much at once to do a back to back on the stock water pump vs electric. But the quick cool down between rounds is priceless, I can be ready for another run in minutes. I have also had no problems on the street.

the issue with making changes you have to do a-b-a testing and do at the same track on the same day. merge collectors and step headers might require a cam change also, so much is related to each other you cant say joe gained a tenth so I should, this is especially true in stock eliminator type cars its the whole package not just one part

Few companies make them any more, but I have had some decent results with the 4-2-1 type collectors, they pick up the low end torque. I built my current headers and used a set of Hedmans on it and they are about 1/2 tenth quicker. compared to a standard 4 into 1 style collector.

I have done water pump and fan at the same time, never one or the other at same time.

My notes below

1) Going from 11” drum brakes to drag race weight disc brakes
My experience was going from ten inch drum brakes to four wheel disks, I saved forty pounds but did not pick up any ET or MPH that I could tell. However it sure stops a lot better and I would do it again. Dual calipers on the back are very much like having a transbrake.

2) Merge collectors vs. standard
I have them on a 2 hp per CI small block but no AB tests.

3) Eliminating the water pump drive ( going to electric drive drive )
There is a good episode on "Engine Masters" where they tested this, big gain if I remember plus the ability to cool faster between runs and mentioned by Bad340Fish. Meziere would be my choice if for no other reason their great support.

5) 904 vs 727 with 2.45 low gear. ( heard .10 e.t. reduction )
The low gear may or may not help you but the 904 is worth at least a tenth.

8) Diamond piston versus old cast piston used in item 7.
In my opinion anything you can do to raise the compression, use thinner rings and have lighter recpicating weight will help. Even at the same horsepower things that will help the engine accelerate faster will help on the track. (My opinion).

You did not mention it but in my experience, documented on the dyno, vacuum pumps make horsepower in engine with gas ported pistons, thin rings and low tension oil rings. Your mileage may vary.

Good luck and let us know your experiences.

Bill Lamb

Getting rid of the stock clutch fan, but keeping the belt driven water pump dropped my ET a tenth on a high 11 sec combo.

Going to an electric water pump over a belt driven pump (electric fan already installed) dropped the ET another tenth on a mid 10 sec combo.
These tests were all done w/ 440 engines in my cuda.

Do it, leave it off for quicker warm ups, cools stupid fast between rounds or after you park on the street and the et gains are real as others eluded to me included picked up a couple tenths going to elec. fan and pump.....

Trans man, you will probably not pick up enough ET to be measured at the track by swapping from a posi unit to a spool as long as your tires are within 1/4 to 3/8 inch of each other on the circumference
I didn't see any gains at the track by swapping to a spool on my old M.W stocker with the 8 3/4 third member, the spool was a "lightweight" racing spool also
The special lightweight racing 30 spline spools are heavier than the same brand and model of the 35 spline spools are also, maybe do both changes at the same time to get better, stronger axles also

I remember an article by Cecil Yother (maker of leak down testers, torque plates etc.) saying a limited slip differential was quicker than a spool in his high 10 second 70 cuda.

I don't recall many other details from that article except that it was flat top piston, iron head 440, auto trans. I'm not even sure what tire size, but I think it was leaf spring equipped ....I wish I could find the article.