Custom/Hybrid boring exit nozzle to get at little more bottom, insted of proppin down?

[Christian_83]

Im thinking i could use a little more bottom on expense off some topend.
My setup i really Nice, with good bottom and crazy mid to highend. So im thinking it could be done by making the prop spin more freely in the bottom. Could this be done by boring the exit nozzle further up, mine is 85mm. Or should try a short pump cone OR try a 12/17 prop ?

 

[Christian_83]

Hi Chris.
Yes i know, at the moment, im running a DASA SS 850 with 180 psi domes (waiting on 200 psi domes) dual 49 full spec carbs, msd tl, pfp exhaust.
The ignition is set at 30 deg static, retard begin at 5000 rpm, retarding 14 degress, and rev limit at 9000rpm.

 

[kevbo]

A smaller pump cone will help, I would try this first. Not keen on going much bigger than 85mm, the nozzle gets a bit thin. If the cone is not enough maybe down pitch the prop. There are other things that come in to play of course ie compression, ignition etc.
Chris.

A short cone doesnt do much. Since your nozzle is already bored find either a flatter impeller or more power.

 

[JetManiac]

What pump?

 

[Christian_83]

144mm solas mag pump from you

 

[964Chris]

A smaller pump cone will help, I would try this first.
Chris.

I agree. Installed a Solas 'MAG' pump and noticed a lot more thrust and hook up, but I lost some bottom end. Bought the solas stubby cone for it and big difference.....bottom end came back with a vengeance.

 

[munki63]

With boring out the nozzle is there any need to bore out the steering nozzle? Or is that just a stupid idea?

 

[Christian_83]

nizzit serious? What engine Setup/prop are you running?
Munki, i dont think so, the exit nozzle is around 82mm stock i recall, and oftens bored up to 85mm.
The steering nozzle is around 90-91mm i think.

 

[kevbo]

144mm solas mag pump from you

In that case try a short cone first.

 

[964Chris]

nizzit serious? What engine Setup/prop are you running?
.

I'm running a jetmaniac/blue bb781, limited b pipe, epic, with a Hooker 10/16 and solas 144 mag, bored exit nozzle, atp steering nozzle....stubby cone made a world of difference. Was skeptical till i put it in. This is in a b1.

 

[swannysxr]

save yourself a headache, and your pocketbook. Call Impros, tell them your setup. They will steer you in the right direction.

 

[munki63]

He has a prop that works, it also about what the rider likes, I wet thru 4 impellers on my last build until I was happy....

 

[Pablo]

Christian,

Try the stubby first before u bore the nozzle. You will prolly still need to bore that nozzle though. The whole issue with the Dasa engines is to get get them spooled up so the PV's can pop. I have run a 87mm nozzle and it definitely helped unload the prop (if ur over propped). A stubby cone, nozzle boring and putting a spacer washer between the prop and stator are all ways to help unload the pump faster. I started with a 14/19 in my 144 mag on a Dasa ss850 and it was too much prop. I'm using a 13/18 with a stubby and 85 nozzle now but truthfully could go down to a 12/17 or 11/16. When I first got a Dasa SS engine i talked with some of the west coast guys who were running low pitch props (10/16 hookers) and getting good results. I'd try more props if they weren't so expensive.

 

[Christian_83]

Pablo, i hear you. Im on a 13/18 Skat trak mag prop. with a 85mm nozzle. I good great bottom, from what 1000-4000rpm (rpm figures, are waht i think - havent read them with a tachometer) i think, but when i hit around 5000rpm, hell breaks loose.
Its like setup up the wake, and when i hit it and pin it (maybe 4000rpm) its good, but if i could hit the setup wake 1000 or 2000 rpm "later" in 5000rpm or so i think i would get much more air ?
I dont need topspeed, i pulls hard from bottom, but mid-top it pulls crazy. And thats what i would like, to move that power band down some?
2x on the prop testing :/

 

[DAG]

What is everyone running for prop spacing in front of the stater? I set my 10/16 hooker with a 5mm gap. Allthough I have a few shims I could space it out further