Chinese Clone Motor on Gas‏ – Engine Dyno

Here’s a dyno pull comparasion of a Chinese yellow clone motor on gas. We started with a stock engine with a stock muffler, put in 16 oz. of 10w30 oil and did a couple of dyno pulls. Engine ran very bad, sounded like a bad spark plug. As you can see by the lower dyno pull engine surged very bad due to very lean condition. Made 4.6 hp at maximum at 3000 rpm. First thing we did was remove stock muffler and replace it with a small header we got from ARC.  Really didn’t help much, engine still very lean. Drilled main jet out to .037″ and dyno again. Engine souded very strong and made big jump in horepower. We then tryed Animal springs instead of stock springs. Really didn’t do anything, in fact lost hp on top end. Went back to stock springs and stuck on large RLV header. Made a pretty good jump in hp. Ended up with large RLV header and .036″ jet. I don’t think this header will be legal for the rules that I skimmed thru very quickly but just for your infomation. I think the small header from ARC ran best with a .035″ jet.  I know A.R.C.  & J.C. Specialtys both have parts for these.
About 5400, this motor really fill off. A couple of people have told me spring pressures will make a big difference but they will not be legal!
The dyno sheet show a comparision of a bone stock engine with how we ended up with all stock parts except for jet change. Tightening valve lash settings didn’t make much differance. Ended up gogin back to .003″.  Max torque was at 3600 rpm, peak hp at 4900 after jet change.

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Stan Hewitt
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Torque & Horsepower in Relation to Engine RPM

Here’s a multiple dyno graph overlay that includes torque & horsepower in relation to engine rpm. You can compare up to 6 graphs at a time, click on any part of the graphs to compare horsepower or torque at an exact rpm and see that number in 1/100ths of an increment on the right side. This also works when dynoing clutchs.  Do a graph overlay and compare in time to see which clutch locks up first with the least amount of slippage. Very handy when testing and comparing headers, cams, pipes, clutches, etc. or any internal or external part that affects horsepower or power to the ground.

At what RPM does your enginge run best? My dyno will tell you…

Here’s a typical 5 hp Briggs engine shown on a acceleration report. The third column is what I like to use, “Corr Time Diff”. Looking on the far left column under engine RPM it shows to go from 4500 to 4575, it takes .271 of a second to accelerate through that time window. This is a bad example because this is a very tired motor but you’ll see that it surges up & down in time as it accelerates. Then at 5775 to 5850, it just drops off drasticly. If this were a race motor, it’s where you’d want to see maximum engine rpm. This is my test motor for testing new dynos and it’s very tired.

The forth column is very handy too. If a customer has three motors and he knows that at a certain race track he turns the motor say 4500 to 6500. He can dyno all three motors and see which one has the lowest “Corr Total Time”, the forth column.  That engine acelererates  thru that engine rpm range (4500 to 6450) the quickest.

Stan Hewitt – Hewitt’s Inertia Dyno’s – Go-Kart – Engine Builder

Contact:

Stan Hewitt

Owner of Hewitt Inertia Dynos

Precision in the shop takes seconds off on the track

Call today to get all the details….

c 641-512-3395

hewitts@netins.net

Bristow Iowa Go Karting Industry Career Engine Builder with decades of experience – G0 – Kart Tracks central Iowa Midwest – Go Kart Dynos – Small Engine DYngine Dynos – The Most Accurate Dyno you will find on the market – have questions want details call today WKA IKF World Karting Federation International Karting Federation National Championships Forest City Jamaica

HEWITT INERTIA DYNOS FOR SALE BOTH OF THESE HAVE 22 HP FLYWHEELS. ONE IS MY PERSONAL DYNO. ELCTRIC START, DIRECT DRIVE (THE MOST ACCURATE), 35MM BELT DRIVE, OLD STYLE OR “NEW” BLACK BOX II DATA SYSTEM. BUY UNPOWDERCOATED OR READY TO USE WHEN YOU UNCRATE. CAN COME WITH OR WITHOUT COMPUTER SYSTEM. I WILL NEED YOUR ZIP CODE TO FIGURE FREIGHT COST TO SHIP TO YOU? INCLUDES TRAINING BY PHONE OR I’LL BE ON EAST COAST NEXT WEEK (FEB 27TH THRU EARLY MARCH). ALL MY DYNOS CAN DYNO CLUTHES AND MEASURE ACCELERATION! DO MULTIPLE GRAPH OVERLAYS (UP TO 6) AND COMPARE COLUMS OF DATA SIDE BY SIDE. ACURACY TO 1/10TH OF HORSEPOWER! NEW SYSTEM CAN HAVE UP TO 9 CHANNELS FOR MULTIPLE SENSORS. QUESTIONS??? HOME/SHOP PHONE 1-641-775-3395 OR CELL 1-641-512-3395. E-MAIL HEWITTS@NETINS.NET- I WILL FAX OR E-MAIL EXACT QUOTE. YES, WE TAKE ALL 4 MAJORS CREDIT CARDS. YES, WE’RE WORKING ON LEASING!
THANKS-STAN HEWITT