EFIDynoTuning Forum

No not a "big" cam but bigger than stock. The 1.73 rockers amplify what it has going on. Stock cams are typically the smallest you will see. Stock are the best thing you can find for idle quality and off idle torque. A bigger than stock cam trades idle and off idle for higher rpm power. I assume driving around at 2500 rpm or above and you will have great power and torque.

edit; the rough idle and chop which sounds nice is the engine struggling to idle. The valve overlap and duration is poor for airflow velocity at that rpm which causes low vacuum and the cool sound. It's all about airflow velocity. A big wide open pipe flowing a small amount of air will have low velocity. also the opposite is true, smaller pipe more velocity.

Thank you for explaining all that. I'm honestly impressed with the idle quality and off idle torque considering it's a truck with 33-in tires. I can imagine the TFS1 in a car has plenty down low. The setup is quite nicely matched with the 3.55 gears and four speed. The only issue is manual first on the e4od will not lock the converter. First gear is definitely necessary pulling heavy trailers up steep grades. When I get some time I'm going to try to set up a tune that will lock the trans in first gear with the shift lever and drive. That should make it pretty much ideal in any situation.

On another note. With a bigger than stock cam where is peak fuel efficiency found?

locking the converter in 1st will reduce power

peak mpgs almost always occurs where the lowest rpm and lowest percent load can be maintained stable for a given gear ratio.

Usually the lower the gear the higher rpm it will be and the higher the gear the lower rpm it will be.

Thats why higher stall tq converters and higher gear ratio rear ends get better fuel economy in the city but worse on the highway.

Ok cool I wasn't sure if cruising in od was helping mpg since I am pressing the pedal down further.

The issue is I tow 7k pounds up a 3 mile 15% grade regularly and second gear will not maintain speed. There is a 25 mph turn at the bottom. With the converter unlocked in 1st the heat generated is excessive and rpms are higher than needed as well. In first with tcc locked I would be able to maintain speed and accelerate easily. The fastest section on the grade is 45 mph which would rev at ~4500rpm.

why not slip the converter in 2nd to maintain speed ?

would keep rpms down and generate far less heat

Tried this today. Engine stayed cooler below 230. Transmission oil was over 260 by the time I got all the way home. That is a full 30 degrees hotter than before. She pulled up the grade fine though.

you'll need two bar and plate coolers with fans on each asap

185 is where you want trans temps.
trans temp above 200 is not good.

you definitely need a supercharger on that thing to help you climb

Yeah I have one large cooler and a deep cooling pan. I've been looking at superchargers but I have to keep my smog pump to pass smog and a bunch relocate the alternator to that location. Any kit recommendations? I also thought about advancing the cam a bit more since I rarely rev past 4-5k. I installed it with icl at 108 degrees. Intake p2v was .240 when measured. Any one tried 104 or 100 icl?

I'd recommend taking an eaton m112 and side mounting it above a valve cover. You'll have to fab everything up yourself as its highly unlikely you'll find anything.

Is there any hope of a centrifugal sc doing a decent job below 3k rpm?

Https://www.ebay.com/itm/255310524650
This looks like something I can tackle with my skillset. Fabbing from scratch certainly is not.