I'm pleading ignorance here, but. There was a guy on Passtime last night that had a 4.6 modular engine with a 671 blower in a 33 Ford coupe. First off what is a modular engine exactly? And he said it was detuned so it wouldn't be as impressive as it looks. So exactly how do you detune an engine? I'm just curious. Thanks

 

It refers to the assembly line. It was a modular design that allow easy change over at the plant from building one engine to the other.

The use of many common parts helped enable that although that isn't the reason for the name.

 

As usual with Ford engines the common name that sticks really has nothing to do with the motor, in this case it's the type of assembly line it is built on. Detuning a blown engine is pretty simple just lower boost levels, but it can also be done by backing down ignition advance or by changing hard parts like cams or pistons. It's nice to see somebody put a Ford engine in a Ford coupe once in a while, what time did this car turn?

 

What is a 671 blower?

Detuning on a blower can also be done by changing the pulley size. If the engine is computer controlled he could also detune it using a hand held tuner or have it done on a dyno, buts its still changing things like the spark, air/fuel mix, etc.

 

Another key aspect of the modular engines is over-head cams, which allow for mutiple intake / exhaust valves.

 

Detroit Diesel made a series of engines with 71 cubic inches per cylinder...there is a 4-71, 6-71, and 8-71, with 4, 6, and 8 cylinders. The blowers used on them increased in size with the increase in cylinders.

The traditional drag racing blower was an adapted 6-71, but now the fuelers are using bigger stuff...

Detroit Diesel Series 71 - Wikipedia, the free encyclopedia

 

They also made 53 series diesels that had smaller blowers. These engines haven't been around in a long time. What a lot of people dont realize is that these were true 2-stroke diesels, no intake valves. They were also not supercharged, due to timing and placement of intake ports in the cylinders the old Detroits were naturally aspirated, the blower simply kept lots of air moving and helped the 'scavenging' process for exhasut.

 

Thanks guys for replying to this.
Conanski, I don't remember what time he had, but it was kinda high for what he had. I think it was in the 12s though.