10/1 Another solid mounted race engine was giving the sled owner fits (wouldn’t pull expected revs in 500 ft), and it similarly gave us fits on the dyno. Fuel flow was all over the place, indicating that the carbs were suffering from high frequency vibes that caused foaming and shutting off the flow of fuel into the carbs. I think that when the fuel in the bowl turns into a milkshake, the floats jam against the needle and seats, then the liquid gas in the bowls gets sucked out, foam subsides and another surge of fuel enters the carbs. I believe this engine will make 10 more HP with rubber mounts (since it leaned to death at high revs regardless of jet size), hopefully we’ll get a chance to see that happen.
10/10-10/12 private pro racer tuning cameras off.
10/13 ZR600 EFI w/ D&D single pipe 720 big bore, several pipes/ chips Dave and his dad drove from Detroit last Thursday evening, hit that monster snowstorm at the border but made it to Batavia luckily had reservation at Super8. I met them here at the dyno Fri AM but we had no electric power to run computers, dyno, 7.5hp air blower, 3 phase hydraulic table lift. So they left sled here, turned around and drove back to Detroit. Got our electricity back Fri PM, so I set it up on the dyno (EFI w/ bypass regulator on rail, lots of hoses to meter fuel).
Dave had complained about poor sled performance (that’s why he came here), and that showed on the dyno as coolant inside engine became extremely hot during 8-14 second runs (est 150 deg F plus). HP was in the low 120s and torque about 80 lb/ft. I removed thermostat and coolant temp dropped 25% and HP jumped to nearly 130 and torque to 84-85 lb/ft. That increase is probably a combo of higher airflow with cooler cylinders, and the ECU seeing high temps and pulling timing (fuel flow was similar on hot and cool engine). Dave may have had defective Tstat or it was resticting coolant flow. I don’t know about water pump volume/ cooling system capacity on ZR600. But if they’re designed to just cool a 100 HP engine and were adding 30% HP (and heat) with the D&D 720 then we could have a problem in the field with hot coolant and low HP. So Dave will install a coolant temp gauge and if it runs much above 120 F he will benefit from additional heat exchangers.
Dave’s coming back Wed to pick up sled.
*******After Dave got home with his stack of dyno sheets and graphs, he posted on Hardcore Sledder that he was pleased to have found the problem with his sled at DTR, Jim treated him right, etc. Dave called me to ask why his post was deleted moments later! My pal Commie Censor Rob is at it again because he’s seemingly banned the words “DynoTech” from HCS for my being an ex-advertiser for being late on my ad payment. But what if Dave was not pleased with his experience here, and posted a bad review of DTR on HCS? I’ll bet it would still be there. Are the names of any other non-advertiser tuners or companies deleted from posts on HCS? I am singled out because I WAS an advertiser there for two years, now I’m being punished for being an ex-advertiser. By being blacklisted by HCS I am surely being made an example of for his other Banner-advertizers. So the bottom line is anyone who desires to discuss anything I do here either dyno-testing or publishing on the website had better do it on ANY other sled website, all of whom are DTR-friendly whether I have a banner-ad or not. And if you Cat people desire to see what Cat stuff I have going and wish to observe and/or interact, it’s best done on ArcticChat.********
10/19 Fusion 900 with custom turbo system, also an XCR triple mod for tuning. Mark’s turbo Fusion has given him fits. No problem tuning boosted Boodocker box, perfect 11/1 A/F ratio but low HP, low airflow, low boost on what looks like a perfect model 53 Aerocharger. This is second time to dyno with similar results, since last session had HTG do turbo porting (similar to what he did on Greg Bennets 300+ HP XC big bore model 66 twin) but still no HP. Will try a different ECU in the field, if that helps he may be back. Al’s XCR SLP trailport SLP pipes tuned in nicely with Holtzman variflow valve. That was my first experience with them, worked great, could tune from 171 HP .70+ lb/hphr leaned down gradually to 185 HP .60 by just tweaking variflow, now has EGT numbers to help him field tune from rich to lean.
10/24 AM Doo 830 RKtech twin for tuning and a bunch of pipes to test.Had wrong date, was supposed to be thursday 26th but we’re still waiting for a few more things to test, maybe later this month.
1 PM Firecat F7 Bikeman trail port BM pipe mod, maybe will need Boondocker (have some on the shelf). Jake lucked out today–his 04 ECU was one of the fat ones, higher fuel flow lb/hr than most 04s. So instead of having to buy a Boondocker from me to add fuel, he only had to choke down top end fuel pressure. The higher flowing bikeman cylinders stock bore with 106 lb/hr fuel flow gave jake 154+ HP, choking fuel pressure down to give him 100 lb/hr made 158+ HP and adding a D&D Ypipe gave him nearly 160 HP. This was on Jake’s 93 octane pump gas, 17 seconds at WOT on hot engine.
10/30 Apex w/ NA trail mods from SD, private test cams off. Lots of interesting fine tuning stuff, cheap moderate but significant NA 4 stroke HP upgrades, maybe sled owner will decide to share results on DTR.
.10/31 10 AM—- RX1 with CPR turbo engine/ Lightning pro turbo kit (draw-through single Mikuni flatslide). Will also blow N2O on top of turbo. this session began negatively, engine would start spit misfire run on one cylinder then get enough cylinders to fire to drive the sled off the trailer, then it died. Restart attempts were futeless, installed frash plugs then it fired up then seemingly drowned in fuel again. Sage and I put the dead critter on our wheeled autopsy table–we managed to muscle the heavyweight modster onto the dyno table. I’ve watched Sean Ray correct many turbo Harleys on our Superflow Cycledyne eddy current rear wheel dyno. First thin he does on troublesome bikes is rip the carb off and check that out. On most turbo Harleys the trouble lies within the carb.
Sage and I pulled the Mikuni HS48 [H-D design] flatslide carb supposedly as delivered by Lighting pro. When Aerodyne was installing HS42 Mikunis on the early HD hits (we did over 1000 of those), and I am very familiar with them.
We dissected the HS48 and found that the float level was too low, preventing the 2.4mm needle and seat from shutting off fuel flow with 4 psi fuel pump pressure. This was apparently causing gas to overflow the carb and fill the bottom of the turbo compressor housing. So every time Sage tried to start this beast it would slug a shotglass full of fuel from the bottom of the huge Turbonetics compressor into the engine, into the cylinders drowning most of the plugs. If one cylinder could keep firing, it could eventually clean out two or more of the flooded cylinders and get running. This was surely not impressive in the pit staging area.
Afterdissection, we discovered that the HS48, as deliverd with the Lightning Pro kit had float level hopelessly uncorrect, could not shut off fuel pump pressure. All we did was set it to factory spec at 20mm and for the first time the engine could start, idle cleanly with no loading and stalling. Time for a preliminary dyno run.
I had Sage drop the boost from 22 psi where they were running to what would be 12 psi. With float level correct, it ran clean at part throttle, we loaded the engine on the dyno, and when oil temp and water temp was optimum we began our first 7 second dyno test. Even with Mikuni’s LARGEST main jet 240 by 8500 we were leaned out to 14.8 and rising [bad] so we aborted test.
Sage and I had an old pal Don Frasier visiting us after his byannual prostate exam. He was exhibiting some misforgivings since, as Don indicated, during the very long exam period the Doctor had both hands on Don’s shoulders.
Don suggested that since we were frighteningly lean with the largest main jet, lets take it out. Great idea.
So with the 240 main removed from the needle jet, we blasted again at 12 psi. This time we added gobs of HP and instead of 14.8 A/F ratio we had 12.4. Dandy and good HP. Thank you Don.
Next we bumped the boost up gradually to just over 20 psi where the engine made nearly 300 HP. A/F ratio remained at a dandy 12.4/1.
Sage tweaked the boost controller on the Turbonetics turbo (an oversize copy of the RayJay 370F40 turbo I ran on my 1977 Kawasaki KZ1000 thirty years ago) and on that next run our live dyno test graph virtually copied the previous run until 9500 where HP dropped like a rock and we aborted the test [real time graphs are extreme engine savers!].
That drop in HP on the real time graph was accompanied by a cloud of steam out the breather vent. This was surely at least temporarily terminal.
Day two, we engaged former Bender Racing engine/turbo/ dyno guru now independant Bender Turbo guy Justin Fuller to repair what we hoped was a blowen[d] headgasket.
Justin Came to the dyno day two with a set of gaskets–on any mod engine a stock headgasket is a perfect failsafe device–going into severe detonation will destroy ANY engine, and a popped headgasket is the cheapest failsafe device to fix.
But in this case, the engine was fitted with very rigid oversize cylinder studs that would try to maintain head gasket integrity even during the ravages of detonation.
But the forces of deto are surely like the 8000 lb Gorilla–unyielding studs create incredible cylinder to head sealing forces, so deto will instead either knock piston domes into the crankcase or yank stud threads out of the crankcase! Something must give.
So it appears after Justin’s autopsy that one monster stud was loose (surely pulled loose from the crankcase threads from deto) and the headgasket had blown between cyls two and three.
There is evidence of extended deto on pistons and cylinder bores–piston domes distorted, squeezing ring lands tight but opening ring end gaps, plus cylinder bore distortion (number three was .006 out of round!).
This drag sled needs a new block, new pistons, and there is an unusual added friction in rotating the crankshaft that may add to the cost of ressurection.
The bottom line in my opinion is that if this Mikuni HS 48 carb did, indeed come with the Lightning Pro kit it was inadvertantly tuned to destroy. The tiny needle jet hood only intrudes into the massive 48mm carb bore by maybe 3/16″ where there is so little airflow that signal at needle je ontlet is not strong enough to deliver adequate fuel flow. How often have you heard of leaving a main jet completely out of the carb and getting perfect 12.4/1 A/F ratio? That stock biggest possible 240 main jet delivered 15/1 death A/F ratio with 4 psi of fuel pressure.
Then Sage relayed to me that on the first field test run, with original 240 jet the boost controller created 29 psi boost [at probably 15/1 A/F ratio]. After that test they dropped boost to 22 psi. So with no intercooler, and the leanest possible A/F ratio Justin and I believe the major damage was done on field test 1. That surely would have deto’d the engine, perhaps begun pulling the middle stud, distorted pison domes/ ring lands and set up the damage that would manifest itself here as being terminal.
I’m hoping that the owner of this sled will repair it (new block, pistons, etc) and bring it back here for proper tuning before it hits the grass or ice.
The stock Mikuni HS 48 carb is useless in delivering safe A/F ratio in this application. They seem to work well on big inch Harley (this carb’s intended application) where incredible multiple carburetion from reversion enrichens mixture to a safe level. Just like on piston port two cycle sled engines, big cammed big inch HD’s have a cloud of fuel vapor hovering outside the carb at WOT–every time air goes in then back out the venturi then back in again it picks up more fuel! But with this suck-trough turbo, the air only goes in, no reversion to help enrichen mixture. I have a plan to copy Joe DiSpiritos tall hood mods he created for SkiDoo carbs many years ago. This hood will be JBwelded to the stock needle jet top, increase signal and hopefully draw fuel from the float bowl as quickly as needed, not one second later.
If that doesn’t work, I will recommend (and almost guarantee) that a single Lectron 48 will do fine in this application. On second thought, a suck-through turbo might not be a good application for a big Lectron–I had a set of 40mm Lectrons on a big block GS1394cc Suzuki back in the mid 80s that were horrible only because when you rolled off throttle to shift, the slides stuck shut and it was all but impossible to reopen them. Unless the new Lectrons have improved their flatslides’ friction, that “stiction” could be a problem with a turbo. The HS series Mikunis have rollers behind the slides to eliminate that.
I truly hope that this sled will be back so we can fine tune before the next 500 ft field or lake blast.