Preferred Dyno Pull RPM Range w/Data

[Barry_R]

Originally Posted by AL427SBF

Barry, to further the discussion ...

Parameters -
1. All engines are in the car and are registered for the street
2. All engines run on pump gas, figure 92 octane max, means Cr probably no greater that 10.5:1
3. Expected peak BHP is ~1 for every cubic inch, e.g. 427 CID is expected to have ~427 BHP
4. Motor was put together properly and broken in with > 2000 failure-free street miles

If a customer came to you for a dyno and requested you measure as much of the power band as is reasonably safe to do, what would be your starting RPM to record data?

Client could have motor sizes of -
a. CID < 351, RPM Start = ?
b. CID 351-427, RPM Start = ?
c. CID > 427, RPM Start = ?

Certainly not Engine Master candidates, but right in-line with good performing street builds.

First I would need to pull the motor out of the car. I own and use an engine dyno. Chassis dynos are great for tuning but the numbers you get have no basis in reality.

Next is that a 1 HP per cube engine in my world is either a pooch or built as a near stocker or towing piece. Something down at that level - assuming proper build and fuel - should be able to be tied to a dock and held at WOT until it runs out of fuel - or the oil temp gets so high that the thing melts into a single blob.

I'd have no problem running one of those at 2500 and my dyno would grab something like that at low RPM without breaking a sweat. But most 1 per cube stuff will be all pooped out by 5500 anyways...so the common 3000-3500 RPM power band holds true.

What you should really be looking for and nobody seems to care about is the part throttle drive stuff. I'll run engines for ten or fifteen minutes at a light loaded 2000 or 2500 to sort & spot check cruise fuel and timing. Even though this is where 90% of the driving happens it's also where owners generally go to the bathroom or call their buddies to report the hollywood numbers....