Dyno............Who Needs A Dyno?

[toobroketoretire]

Rather than paying someone to dyno my engine I have always run 60-100's timed with a stopwatch. By running the 60-100's in high gear only I avoid problems with wheel spin and shifting and only raw torque is doing the job. The effects of any jetting change or other modification I make immediately shows up on my stopwatch. Plus it's fun to blow the cobwebs out of my engine every once in a while.

When I switched from a 220/220 duration .500"/.500" lift cam to my present 236/236 duration .556"/.556" lift cam I found my 60-100's took the same amount of time but by running 70-110's it runs about 1/2 second quicker because of the higher rpm torque band.

Do any of you run 60-100's to periodically test your engine?

 

[Antz81]

I think this explains a few things

 

[KANE]

Ideally, some sort of dattalogging program capture & recording program - but you need to have an ECM to do that.

You can see real time what is happening with RPM, speed, A/F ratio, etc, and acceleration times.


I think there is an App in the iPhone store that does the same thing as a G-tech. It's pretty inexpensive from what I have read.



If you are really serious about nailing the tune, a wideband O2 sensor in your exhaust would show you what your A/F ratio was during those periods. You'd see what was happening with pumpshot as well as WOT. You could confirm if you are in the range for 12:1-ish A/F ratio on hard acceleration.

Just a few thoughts.

 

[toobroketoretire]

Yes, I can spend money to buy things that will indicate a performance increase (or decrease) but a good old 60-110 doesn't cost me a dime other than the fuel used AND I get the thrill of going fast for a few seconds.

 

[Tuna]

Trying this again.

A single speed range for an acceleration test is inclusive when trying to validate power changes after an engine change. Most changes, especially cam changes, move the power band up or down. If the gear ratios are unchanged, the RPM band seen in the 60-100 test may not be in the engine's new power band and will not result if a valid observation of power changes.

Multiple speed ranges (RPM ranges) need to be documented to establish a baseline for the engine then all ranges must be tested again to see if there is an observable power change.

I'll add that all these test need to be done on the same road, same temperature and pressure conditions and same tires to be anywhere near valid.

 

[toobroketoretire]

In the past years I have always used 60-100's to judge my passing performance. When I installed my longer duration magnum cam I found my time was the same but when I increase the speed to 65-105's my time is about 1/4 second less because of the cam's higher torque band. A simple jet change will show up as a several tenths difference so it's a pretty accurate method of judging performance differences.

 

[Tuna]

You just proved my point.

 

[Hib Halverson]

Rather than paying someone to dyno my engine I have always run 60-100's timed with a stopwatch. By running the 60-100's in high gear only I avoid problems with wheel spin and shifting and only raw torque is doing the job. The effects of any jetting change or other modification I make immediately shows up on my stopwatch. Plus it's fun to blow the cobwebs out of my engine every once in a while.

When I switched from a 220/220 duration .500"/.500" lift cam to my present 236/236 duration .556"/.556" lift cam I found my 60-100's took the same amount of time but by running 70-110's it runs about 1/2 second quicker because of the higher rpm torque band.

Do any of you run 60-100's to periodically test your engine?

I have a wideband permanently installed in the exhauts of my 71 BB and I have an Innovate LC2 I use in the other cars, each of which has a wideband O2 bung in their exhausts. I move the LC2 from car to car as needed.

With the 71 and the wideband, I run third gear pulls from 1500 rpm to 6800 rpm and record the display. I look for 12.2:1 AFR. Admittedly, that's just a scosh rich but I'd rather be a little on the rich side at WOT and take the slight power drecrease.

 

[toobroketoretire]

Yeah, I'd rather be a tad rich too. Like several million dollars rich. Darned shame we didn't have movie stars for our parents.

My old Harbor Freight twin cylinder air compressor pump took a royal dump this morning................seized and snapped a connecting rod and one intake reed valve had broken. Oddly enough it was full of oil so I guess the rod just got so hot it seized. Before I reassemble it I'll drill two small holes in the top of the rod's big ends to help more oil get into the bearing.

 

[kpic]

You just proved my point.

He is good at that.
BTW, your comment was a keeper. Unfortunately there is one person here who didn't get it; however, everyone else did.

As she has a blower, she is running a lot richer than what has been posted. The way it was set using a dyno was make a run until she sputtered then add 1-2 points to the right of the decimal for safety.

She has a Walbro fuel pump and a KB boost-a-pump. As the Walbro supports up to 17 volts for extended periods of time, I can load additional tunes that increase or decrease RWHP by changing the F/A etc.

 

[SVO]

If you are running forced induction, an hour of dyno time is cheap compared to burning a hole in a piston. To self tune, one needs at least a datalogger, like the Innovate LC with a wideband to tell what's going on.

 

[kpic]

If you are running forced induction, an hour of dyno time is cheap compared to burning a hole in a piston. To self tune, one needs at least a datalogger, like the Innovate LC with a wideband to tell what's going on.

Quite inexpensive as compared to rebuilding an engine. A fuel pressure gauge is also common sense.

 

[toobroketoretire]

As my '71 is a daily driver I'm not concerned if the air/fuel mixture is perfect for every instance. I probably give it a full throttle no more than once a year and when I do it's only for a very short length of time; 2-3 seconds usually being the maximum. Some day when I'm bored I may make a few 70-110 mph runs with the stock metering plate and a few with it .002" to .003" larger. Just that small amount would show up as a quicker or slower time. Before I installed the Ram Air I was getting 6.5 second 70-110 mph runs which is a LOT quicker than the 8 second 60-100's I was getting with my 220/220 degree .500"/.500" marine cam and 3.70's.

 

[kpic]

110 MPH on under inflated tires?

 

[Antz81]

A simple jet change will show up as a several tenths difference so it's a pretty accurate method of judging performance differences.

You could likely get few tenths of a second difference just in a difference in your reaction times from one run to the next. For big changes, sure it will show them up, but for small changes it's not reliable.

You are right about it being fun though

 

[toobroketoretire]

As a 60-100 or 70-110 usually takes anywhere from 6 to 10 seconds any tiny change you make will show up as a fractional second gain or loss. I like to call them a "poor man's dyno" because they cost nothing while revealing power increases or decreases.