Turbo FZ Build

[mittens]

Re adjusted my wastegate pre-load from 5mm to 8mm. Then baselined it at waste gate pressure and is now 12 on wastegate only.

Then worked my way back up with the boost controller. I got the ski to run 16.8-17.2 lbs of boost where its at now. This is producing a sold 90mph in Alabama summer heat. every time I made a pull its touching 90 now consistently, and 9360 rpms seems to be where its peaking... so probably time for a new stock 13/20. should bring rpms down some, and then allow me to ad 2-3 lbs of boost.

[Astrofizix]

That is great speed for that boost level. Is 13/20 the tallest gearing so to speak that you can run? Because it sounds like with the extra boost you are planning, it should have the berries to push a big impeller.

[mittens]

A untouched 13/20 seems to be the one most like with a turbo if staying somewhat normal. To much prop & will take me out of the sweat spot. I don't think it's going to gain too much more mph from 3 lbs of boost. Maybe 2-3? Guess we will see its a lot of fun how it is. But never know unless you try it. Wish I knew what my prop was tweaked too.

[mittens]

So after researching more why the boost is dancing around back soild. Got a boost leak checker (could have made one but close to same cost & easier to buy) pressure tested turbo to motor. & had 2 couplers leaking(not sure how) & I found a crack/pinhole leak at the little support bracket on the cold pipe.. I fixed the coupler leaks. Welder will touch up the pipe next week. But with couplers fixed boost went up to 19-20. So I backed it back down & will play once all leaks fixed & stead.

Ski has made 90 or 91 on every pull since. Yesterday it was 93 degrees out Alabama humidity.. still same speeds... prettt happy. Just some tinkering to get leaks all gone & soild steady boost & then will turn it it up till prop runs out.
most pulls are 9150 rpms but then some are 9360. So not sure if I will run out of prop instantly or not. But with cooler temps for sure will.

[Astrofizix]

Interesting, I would not have thought boost leaks like that would be common, so good that you found it early.

Back to the prop gearing thing, I want to know if I am thinking about this right: In order to get that extra 2-3 mph from the 3 pounds of boost you mention, you would need to be spinning the motor at higher RPM right? But if you are spinning it past peak power, then a taller geared prop (which simply means larger numbers right) will allow you to closer match the ideal (peak power) RPM to the top speed, is that right?

In other words, too short in the gearing and the engine is spinning past peak power RPM to get to top speed, and too long in the gearing and the engine won't have the power to pull all the way to peak RPM, and your top speed will be below that. So in an ideal world, your prop gearing would be such that the max speed you get in typical conditions will be just at the very peak of the power band.

[mittens]

yea basicly prop pitch is like the rear gear on a car.

right now 17 lbs, and getting close to the limiter, so cold weather will bring it to the limiter, and more boost (I think) let alone both.... so a little more prop. and then leave more head room for boost/weather changes.


I need to put a prop gauge on my tweaked 13/20 first to know what I am a least dealing with. that and fix boost leaks.

[mittens]

OK got boost leaks fixed. (crappy couplers and the hard welded mounts to the cold pipe supports cracked) SO I chopped off ends of cold pipe with cracked supports, added new ends, and now is rubber supported pipe clamp supporting the cold pipe.

New nice couplers and better clamps. leak tested and all good.

95 out with a heat index over 100, water temp mid 80s. Ski is set up at 18lbs it spikes a little above that and then settles 17.8 ish WOT, so we will call it 18 lbs. Ski ran 91 at 9350 rpms with this set up multiple times yesterday with bucket of beer in the back and my 248 lbs on it, and few tools, spare O2 in bow. 9500 limiter.

so the current prop is topped out. if I turn it up any more would be on limiter. I got a prop gauge set, so will be pulling prop and seeing what I have, and then go from there. Probably order a new 13/20 and see how much it drops rpms it in the heat, then see if 20 lbs can spin it to 9350 again in the heat or not. and then play with that as it starts to get cooler.

I ride more in heat then cold so probably will lean to a set up that works good in heat then is all out in winter and drops back in spring Can always dial boost down to keep RPMS down when cold.

[gzk]

could you share picture of your build improvement ?

[mittens]

Sure.

If you look back you can see how I had aluminum brackets welded to the cold pipes & they attached to the valve cover/ head. Well the vibrations of the motor caused cracks in the cold pipes.... so cut & removed those ends on both cold pipes, removing the brakets/cracks, and welded new ends on. Now you can see it's supported with a stainless pipe clamp that has a rubber insert so the pipe should not be damaged by the vibrations of the motor but still make the cold pipe set up solid. So far so good. also replace both Cold side Couplers with nicer 4 inch long couplers with better clamps.

[gzk]

Thanks will upload my build topic soon