July 2006

Monday, July 17, 2006

DynoTech : Month of July

Tuesday 7/18 finishing up Billy Howard's Bikeman big bore Mach Z twin, cast cylinders, 1250cc. Crankshop quiet can big bore twin pipes, Boondocker tuning. Last session last week was over 156 lb/ft CBT and 230 CHP (should have had cameras on, but Billy wanted private session in case the numbers were poor, didn't want anyone watching us struggle. But now we have a big bore that surely works. Bikeman is sending us two more sets of chambers to try (lower and higher comp). Then Billy is planning to squirt his Boondocker N2O system to shoot for 300 plus (that's the new Champagne number). Dyno session today, began with usual repeat run to back up previous session last run,  down over 1 lb/ft to 155 and down 1 HP to 228.9  very unusual and disconcerting but that was all she had,  Billy pulled head to change to revised squish chambers, discovered damage from a piece of wire than left serious pock marks on heads/ pistons, hoping damage-caused debris was out the exhaust, installed new chambers fingers crossed, ran one 10 sec pull 160 lb/ft with 233.2 HP at 7800, but repeat run was down 20 HP and we quit, the autopsy showed serious FOD (foreign object damage) to piston head and awful gouges and cracks in cylinder wall from circlip popping out of one side of mag piston and wedging part of itself between dome and cylinder wall. Bikeman will have a new cylinder  in our hands Fri AM 7/21, hoping to drink some 300 N2O HP champagne in PM.

Thursday 7/20 Curtis Emery from DNE coming with three Yamaha 425 4 stroke flattrack racing motorcycles (one bobe stock for baseline, one stock cc full mod, one big bore stroker I think 500cc plus.DNE Curtis Emery modded flattrack Yamaha YZ450 mod and big bore stroker picked up 10% torque/ HP by A/F ratio dyno tuning, with broader HP powerband.

Fri AM Billy Howard will reassemble 1250 Mach Z live on dynocams,  late AM we'll dyno tweak to max, then add fuel to relax engine to .700 lb/hphr pump gas spec, then blast N2O juice with Billy holding button, maybe we'll sip some 300 HP champagne.Billy received the fresh cylinder this AM, reinstalled with new piston and a new high compression head, did breakin on dyno then saw maybe a one and a half to two HP drop in peak HP that bewildered us. We tweeked timing up and down, jetted up jetted down (not really jets just quick clicks on the Boondocker). It was just simply down .8 lb/ft and just over a horse and a half. We stopped tuning on high comp domes, switched to "pump gas" domes and Billy discovered his new cylinder has ex port over one mm lower than it should have been and booster ports visually smaller. That's surely the result of  buttholes and elbows flying at Bikeman, sending a cylinder blank red label the same day to chrome to be shipped red label the following day to DTR, trying to  finish this project on my dyno (other sleds waiting to dynotune Sat AM and Sun AM). But really what's a couple of HP on a 230+ HP engine? Never feel it in the field but I must say Billy Howard's not happy with knowing the engine was down from 233 to 231 HP. He was a madman, dialing in everything he could, pulled plugs after each run, tweeked fuel from side to side, we ran 26 dyno tests, 231 and a few tenths was all it had. He finally relented and after pulling the high comp heads discovered the port differences, that was the cause of the HP drop. Very very slight but surely bugged Billy H. But there was great relief knowing an ex port variance caused the HP drop. An hour with his die grinder will fix that.

We had spent maybe 4 hours trying to tweak that freshened up motor to match the one we beat up and made so much HP with a loose circlip dancing about in the engine on Tuesday. Here is one advantage of a brutally honest dyno operator. I brag that I don't GAF what HP any engine makes on my dyno, but I really do. But I refuse to "tweak" any HP reading for anyone anytime for any money. Any comptuterized dyno operator can add or subtract 100 HP to a readout and you could not detect the deception (but I could). Billy my excellent friend was hung up on trying to match the Tuesday HP, and was really just stuck .8 lb/ft low. Billy was flustrated (a word John T. Cowie coined to combine his being flustered over being frustrated trying to find HP on the dyno). I could secretly have added .8 lb/ft of torque to that rebuilt engine, matched the original HP with a few pretend HP and Billy would not have known and have been very happy. Would that be a good thing? Would that make his sled faster? But then when Billy removed the heads and discovered the innocent but significant goofup on port size/height we were both relieved there was a reason for the HP drop, not the dyno reading differently from day to day, or something else wrong with the engine. Finally we were both happy.

Billy installed the lower compression heads, and we tweaked fuel and timing back and forth, wound up at 229 and a few tenths, Billy was really hoping for 230 once again a touch of dyno sickness but it was what it was today. Another MM on that new cylinder Ex port and yes 230 plus no problem with low compression max HP tuning.

Finally we fattened up fuel dropped HP to the low 220's with high BSFCs to be extra extra safe before N2O dyno testing (Boondocker boxes are so easy and delightful to tune here). Then we went to hook up Boondocker N2O system Billy discovered he's left his nitrous oxide solenoid at home in Coutersport PA 2.5 hours away. So Billy drove home, I went swimming with my son, Billy will be back at 7:30 AM with his solenoid and I hope we can sip some 300 HP champagne (with OJ) before my next dyno session at 9:30 AM (the 950 big bore Rev twin with more N2O juice).

See you saturday AM 7/22. Sat AM met Billy at 7 AM at the dyno, reestablished na baseline, then began using only two out of the four N2O nozzles Billy had in the airbox. We made 280 with two nozzles but before we added more nozzles we bumped Boondocker N2O setting to try to get the 160 lb/hr that I thought we needed for 4 nozzles. All we could muster  with boondocker set at 99 about 148 lb/hr, about flatlining from 7000 to 8000, so we're betting the injectors were wide open. So like the HP Nazi I allowed Billy one run with a third nozzle connected (the 10AM Rev was coming in 10 min), and luckily we popped 300.1 CHP, which is way better that 299.9.

Sat AM 7/22 10 AM dialing in a Rev 800 HO big bored to 950 I think. Then I we'll be spraying N2O juice in this one too. This one had to go down 200 jet numbers to get fuel flow correct, close to 170 CHP at high .60's. Then their Boondocker carbed system suprised me with 210 HP out of a 40 HP squirt. Fuel flow was lean at .59, but surely didn't load up like the last one we dynod. Before we could tweak fuel up to be the way I like it we snapped the plastic fitting that connects the Boondocker solenoid to the lines and we were done. I should try to post this information.

Sun AM 7/23 Dan Forte and Dan Tripod Cross dyno tuning their hopefully not-so-obsolete 1000 prostock Polaris Storm. Have original HTG mod pipes plus a srt of Jaws mod pipes to try. Surely no 300 hP champagne but hoping for close to 250. After tweaking ignition timing, fuel flow (very smooth fuel flow numbers with factory motor mounts), worked our way up from 225 to 250+ HP with the HTG pipes, Jaws pipes only added a couple of HP on this one, at 750 higher RPM.