nzjetboating Web Board.

nzjetboating.com Forums => Projects => Topic started by: D696 on July 13, 2021, 12:09:23 PM

Title: Single stage Jnr
Post by: D696 on July 13, 2021, 12:09:23 PM
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.
Title: Re: Single stage Jnr
Post by: Allen M on July 14, 2021, 08:54:57 AM
What have you got in front of that?
Title: Re: Single stage Jnr
Post by: D696 on July 14, 2021, 10:14:31 AM
Its a single stage
Title: Re: Single stage Jnr
Post by: Paul on July 14, 2021, 10:18:01 AM
Allen means, what engine..
Title: Re: Single stage Jnr
Post by: D696 on July 14, 2021, 10:36:16 AM
Oh my bad , its a EJ20 turbo, bigger turbo , larger water to air intercooler
Title: Re: Single stage Jnr
Post by: Jeff B on July 14, 2021, 10:51:49 AM
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.
Title: Re: Single stage Jnr
Post by: D696 on July 14, 2021, 10:59:01 AM
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.
Title: Re: Single stage Jnr
Post by: Jeff B on July 14, 2021, 12:55:12 PM
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.
Title: Re: Single stage Jnr
Post by: Jeff B on July 14, 2021, 13:11:51 PM
But let us know how it goes, if it hangs on ok and drops rpm for same speed it's a winner  b>
Title: Re: Single stage Jnr
Post by: Kakapo76 on July 14, 2021, 14:51:00 PM
With My Turbo 1800 on a single-stage colorado- I had to go to 15deg to get the best performance (Southern Jet Bullet)
Title: Re: Single stage Jnr
Post by: D696 on July 14, 2021, 14:59:32 PM
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?
Title: Re: Single stage Jnr
Post by: Kakapo76 on July 14, 2021, 16:31:35 PM
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)
Title: Re: Single stage Jnr
Post by: D696 on July 14, 2021, 18:55:44 PM
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
Title: Re: Single stage Jnr
Post by: Kakapo76 on July 14, 2021, 23:33:13 PM
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.
Title: Re: Single stage Jnr
Post by: Warwick Marflitt on July 15, 2021, 09:18:13 AM
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  B))T speed....