New tnt pipe tuning help!

[d_moss]

Chan hull, bb850 non pv. 148 pump 8/15 prop. Mikuni 46 dasa mani vforce reeds.

Water is pretty cold and with the 87 jet in the pipe I can still touch it.

But most annoying thing is it has a light switch power band just below planing speed. B pipe I could hold steady throttle and make my wake. I have to absolutely blip the throttle with the tnt. If I don't ski goes way to fast. If I have to little steady throttle it rides nose high and I tip over.

How do I bring the power band lower

Flow valve adjustments?, bigger pipe jet?

Also now that I am running dual cooling how do I restrict water flow to bring engine Temps up a bit?

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[newbee]

http://cold-fusion.pinnaclecart.com/hull/adjustable-flow-water-outlet/


That will help with getting the motor temps up

 

[Joe Dart]

I didn't realize engine temp mattered that much until it wasn't getting warm enough. I installed dual cooling on a fresh build and thought, the colder the more power. When I would pull up to the bank, pull the hood and mess with carb settings it would RIPPPP off the beach for a sec. Then water flow would cool the engine and I was back to crap power. Finally found that I needed to restrict head flow to 11/64"(4mm) on both outlets from the head "70 degree water". To do this I first used air compressor line vall valves then drilled some round stock I had laying around. I used a cheap digital thermometer in a zip lock bag to test my engine and pipe temps. It seems like the bolts holding the cylinder sleeve to bottom end will be 160 Deg F and other temps will vary even going as low as 130 deg F. This will make pisser water (right off the head to pisser "front outlet") right at 120 deg F. I could not believe how much of a difference changing the dry pipe temp affected the performance of the engine. If I keep the pipe external temp around 160 deg F the powerband will be higher in the revs. If I restrict water flow even more (install tee), the bottom end hit increases. The pipe temp I like best on my hand made dry pipe is 180-190 deg F. A cold engine will also run rich (black or wet plugs) with no changes to the carb at all and simply raising engine temp, you will lean the mixture. Seems like they are in full self destruct mode, the hotter the leaner and the leaner the hotter. One more thing, the factory temp sensor on my 61x was messing with the ski too. I removed it (gets hot, allows continuity and ebox limits rpms to annoying missing.)Also my wetjet manual states that it uses the thermo switch to retard timing when engine is cold for easy starting. Making water flow through both top fittings equal is also important because one cylinder will run hotter than the other making even a single carb engine run leaner on one cylinder. This is all from personal experience and things might be different on your boat, just my opinion.