Don Terrill’s Speed-Talk

Here is an engine with everything measured as closely as possible (flowbench data, Cam Dr. data, etc). Power curve mimics similar builds very closely. This is a 2 valve, single cylinder application. Peak power is at 7000rpm, which is what the traces below are from: Pressure (exhaust and intake take...

I'm looking at my pistons and valves. A thought came to mind: piston porting that's beneficial with some cams may be detrimental with some other cams? If the cam pushes the valve all the way out to the bottom of the pocket, clearly I could improve flow by porting the pistons. If on the other hand t...

Truckedup wrote:Crazy, watch the till the end...

https://www.youtube.com/watch?v=_TDFxhFXj2A

In high school, one of my friends did the same thing with a stove bolt six in a junk '54 Chevy ... except it just got hot, slowed down and stopped. Next morning it fired right up.

200 MPH, running strong, past the 4 mile marker (Bonneville) then no power, smoke, clutch in, pull the chute, hand on the fire system, coast to the side of the course. It seems that someone (probably a bean counter) decided the keyway used to secure the small sprocket on the cam drive intermediate s...

It seems that the brush hone does not remove metal peaks to create a plateau finish. Instead, it merely cleans debris from the grooves, which is useful but not its intended purpose. Does anyone have a brush hone, polished mirror finish metal surface and a profilometer? It would be a simple matter t...

I have a question...the photo is a new Ducati 1200 super bike piston...these are limited production but street legal bikes. 205 HP, that's nearly 3 HP per cubic inch from a two cylinder N/A engine while meeting some sort of emissions standards. It's a 4 inch bore.......Notice the sharp edges on the...

David Redszus wrote:The acetone will dissolve the acetate and will form a casting of the honed surface which can be viewed under a microscope using a side light.

Very good tip. What level of magnification is needed to make this useful?

If it's a brake, roller speed and torque are all you need to calculate HP, but you need accurate engine RPM to plot an engine HP curve. Similarly, on an inertia dyno, to calculate HP, all you need is roller inerta and rate of change of roller speed, but you can't plot HP vs engine speed without simu...

If there is no overlap in the port, use fig 32 and divide cylinder displacement by two because you're feeding one cylinder with two venturis. Are these 40 DCOE's? 28mm to 32mm would be appropriate ... 28 for street, 32 for max HP with high compression and an aggressive cam. BTW I have not found long...

I have experimented with IR thermometers and found some interesting results. You can measure the cylinders of the block with a temperature at 70 degrees hours after you've last honed the block and come back the next day and check the block at the same 70 degrees and have it shrink by .0002"-.0...

Just what purpose does the brush serve that a 400 grit stone does not? Does anyone have some actual surface profilometer data or are we just talking? Brush Research has published some microphotographs of a cylinder surface before and after using their product. The folded-over burrs from using a rig...

Lower, due to more traction loss in a lower gear, (more Torque, easier to turn the tyres if not correctly strapped). Good point ... Higher, due to the Inertial losses of the wheels having less effect in a lower gear (more Torque). Here you're trying to break the laws of physics. This 1:1 rubbish th...

Does the rear end gear ratio change the dyno readings ? How bout running a manual trans in third gear instead of fourth ? JOE SHERMAN RACING What I can say on this is when I was having the initial tuning done on my turbo6's fast system the dyno operator was doing the pulls in 2nd gear on the 200r4 ...

Each pair of spur gears will absorb 2%-5% of the transmitted power. The higher the ratio, generally the higher the loss. If fourth gear is direct, you will still have lubrication churnung losses, but almost no gear loss. I would expect higher loss for higher ratio hypoid gears, but design and setup ...

Rule of thumb is to run as much advance as you can before detonation starts.....It's not going to be the same at one rpm and load as it will at another though, might be more advanced or might be retarded.... Maybe not, running an engine not overly prone to detonation on high octane fuel you be able...