Shamu

My friend picked one up and will be trying it soon -- I'm not sure of it's claims though...anyways, check it out and let's get some discussion going!

http://www.charm.net/~mchaney/homedyno/homedyno.htm

jerrypeterson

Talk about a do it yourself project.

Suzuka2k

Um....

from the website...

"Connecting Things Up

The first step is to connect the inductive pickup to a spark plug wire. "

This might prove a little difficult with the coil on plug configuration...

Might be something to play around with tho...kinda like a g-Force for HP.

josh3io

if u get a decent inductor u can just tape it to the top of the block. that's how they do the emissions RPM monitor

Shamu

I'm just wondering if their 'theory' is sound -- for the price they're charging, they could drive dyno's out of business if what they're saying is true!

RicePimp

Sounds good. I would guess that as you get more power, avoiding wheelspin becomes the major issue. In the s2000 this is a non issue unless you have a turbo or something as fast. As long as you aren't spinning your wheels it should be fairly accurate as long as all the data for gearing, tire size, etc is correct. The other areas to look out for would be wind and road inclination. As long as you keep these factors to a minimum your results, even if a little off, should be consistent, which is what is important for tuning. Even if it's a little off for the wind resistance calculations it wouldn't be very hard to calibrate it by just comparing to a real dyno chart for the same car. I think it sounds pretty cool. Especially for less $$$ than a g-tech.

E30M3

I have one. It works well and is within 1% of dynos. BUT. It can be fiddley and on some cars it has trouble with noisy signals which can corrupt the files. But if you get it going it's fine. You enter weight, weather, gearing and other info. It compares the number of sparks per unit time to derive the implied output. This is a sound approach. Wheelspin throws it off as you would expect, but it's also immune to bump noise which can sometimes affect the results of accelerometer based units although that is easy to deal with. Very easy to compare things with it. With an individual coil per cylinder you just hook it up differently. I haven't tried mine on an s2k.

Another good unit is the AP-22 at www.race-technology.com That one measures the g-forces and datalogs them. You connect it via serial port to your PC. You can upload files or just record activity directly to your PC for no data storage limit. That is you can use it alone and record to its memory or record to a notebook PC or just read results off its screen. The best analyses require spreadsheet efforts. I use mine quite a bit. It's the size of a tall radar detector held sideways. It runs on 2 aa cells and has no wiring to the car. No backlight. I stick mine to cars using the supplied no mar blutack gummy adhesive. you can get it to 1% match or better to a dynojet if you calibrate it to your car carefully. Even without doing that it's very good for relative comparisons of say intakes. You can also apply SAE correction factors via your PC as the road dyno does.

Stan

Shamu

Thanks for the info Stan.

Regarding the home dyno, how does it measure peak hp/tq? I mean, do you have to redline it at a certain gear to get some measurements?

E30M3

>>Regarding the home dyno, how does it measure peak hp/tq? I mean, do you have to redline it at a certain gear to get some measurements?<<

You don't get just the peaks, you get entire torque and HP curves!

You do need to do it in one gear though just like a chassis dyno. How does it do this? Well we know the weight and gear ratios and tire size and so forth. So we then know that X RPMs = Y Road speed. And then it's just basic High School Physics fornulas - cuz you get the changes in the velocity of a known mass in a known amount of time. You don't measure 1/4 mile times with the unit. Although you could sorta do it now that I think about it.

There are also pricier approaches using the same pulse counting ideas. BTW this is a way that high dollar racing operations spy on each other. You can get dyno curves of competitors engines if you know some other facts via other means such as radar/laser. Right from the side of the track using microphones basically.

Stan

Shamu

When you say you do have to go at it in 1 gear just like a chassis dyno, can we use any gear, or do we have to use 4th-5th to gain the closest 1:1 ratios? If we do have to use 4th-5th, that could be a problem given the speeds we'll be at by the time we hit redline!