Single stage Jnr

[D696]

Anyone else on here running or ran a Colorado Jnr with a 21deg bullet blade?

Only curious , already have new blade , be a while before it goes in.

[Allen M]

What have you got in front of that?

[D696]

Its a single stage

[Paul]

Allen means, what engine..

[D696]

Oh my bad , its a EJ20 turbo, bigger turbo , larger water to air intercooler

[Jeff B]

The original hamilton "130hp" impeller is about 21 deg. I didn't have much luch with it holding on (slipped) to turbo engine.
I found finer pitch held on a lot better and allowed engine to make more power.

[D696]

Ok interesting, my old blade was 19deg south Canterbury jet bullet , motor wouldnt slip on that / but spin it to 6000rpm (79km on lagoon) with blade built up  , so figured up the pitch for new blade , its a southern jet 3 blade stainless.

[Jeff B]

Yeah I'm kinda thinking the opposite. I believe you cant go very coarse with front impeller, or leading edge on single stage. They just won't grab the water efficiently. If you look at ski impellers (where I look as they perform really well, just not for long) the leading edge is always quite low, 10-15 deg (progressive pitch)
You might find the coarser impeller drops rpm but when boost comes in it will possibly slip.
Single stage pumps are quite a balancing act to get good hookup.
A lot of people end up 2 stage upgrade.

[Jeff B]

But let us know how it goes, if it hangs on ok and drops rpm for same speed it's a winner 

[Kakapo76]

With My Turbo 1800 on a single-stage colorado- I had to go to 15deg to get the best performance (Southern Jet Bullet)

[D696]

With My Turbo 1800 on a single-stage colorado- I had to go to 15deg to get the best performance (Southern Jet Bullet)

How much hp is your motor? What rpm / speed?

[Kakapo76]

Around 200-210 realistically based on an NA base hp of 140 at 5200 rpm so with 8 pounds of boost that would equal 216hp: (140/ 14.7) x 8 = 76hp plus the NA base of 140.

Never quite hit 5200 rpm but got close.

Hit 78 kph on a lake with full fuel 3.4 Westlander (very heavy for size)

[D696]

Around 200-210 realistically based on an NA base hp of 140 at 5200 rpm so with 8 pounds of boost that would equal 216hp: (140/ 14.7) x 8 = 76hp plus the NA base of 140.

Never quite hit 5200 rpm but got close.

Hit 78 kph on a lake with full fuel 3.4 Westlander (very heavy for size)

Interesting, the Colorado tech guide says it only take 120hp to spin a fine blade to 5000rpm, did you actually try a more aggressive blade option? My friends sr20de which makes 150hp on a good day would turn a 19 to 5000rpm

[Kakapo76]

I opened my unit up to 119mm gave me the best holeshot and highest rpm- from what I have heard southern jet impellors soak up a lot of hp- I had zero slip. TBH I am running a 3 litre v6 on the same impeller and its spinning to 6000 wot and that's 200hp at best. Its likely I was not getting as much HP as I calculated with the turbo. there's so many variables- intake size, torque curves, nozzles, etc etc its not easy to do straight comparisons.

[Warwick Marflitt]

It's like having a car with a torque converter with no gears and then trying  to get the right diff ratio that allows you to have enough ratio for hill climbing and flat out  speed....