Need big HP pump advice

I've got my ski pretty well dialed in. The last two modifications should ahve helped bottom end, but they really didn't in fact ATS_Scott thinks the bottom end got worse.

MSD total loss. 27 degrees initial timing to 5500, then retarding to ~16 degrees around 9k.
higher compression domes (200 psi)

The engine is 946cc Lamey PV billet cylinder, +8mm Crankworks stroker crank (thanks Team Scream), Team Scream ported cases trenched and epoxied by DASA (girdled by me), older Novi 48mm dual carbs jetted by me.

The midrange and top end are INSANE! The ski accelerates FAST, like 1000cc sport bike fast.

The problem is the bottom end just isn't there, well I think it's there but I can't get the pump to hook up. If you do a real slow bounce like to do a flat water back flip is just barely hops out of the water, but if you can carry a little speed and then hit a good setup wake or a boat wake it goes nuts.

If I stand in the back of the tray and half throttle it, it will just about yank me off, but if I go full throttle it feels like I have less thrust. I don't think it's a jetting problem either, Superramjet rode it and said he thought the impeller was slipping down low too.

I need to get the tachometer back on it to make sure it is revving out like I think it is by ear, but I seriously believe the problem is the impeller is ripping free. I have spent most of the summer trying out different impellers. I started with a 13/18 Solas with all the Impros modifications and am up to a 14/19 Hooker with a TBM pump stuffer on a blue printed stator. That is a huge gap, considering that Impros recommends like a 10/16 Hooker to replace the Solas 13/18. I've got a Skat 15/20 big hub impeller to try out today, but that is basically my last ditch hope for getting the stock pump to work.

I called Skat Trak yesterday and told them I legitimately thought I was making 160hp and wanted a pump with good bottom end and I didnt' care if it wouldn't do over 35mph. They said I should go with their one piece billet 148mm pump. This was all great, until we got to the price:

pump $2200
drive shaft $420
reduction nozzle (might include the trim setup?) $720

That's like $3500.

Ouch. Have I really gone this far?

So am I desperately looking at other options, like:

older style 148mm Magnum pump. I've seen these for GP1200's and they usually sell used for under $500. What reduction/trim setup could/should I use? I think these setups start out as a 155mm setup and get resleeved down to a 148mm by Skat track. That means it could be HEAVY like the 140mm Skat Trak Magnum...but my ski has no foam out back and floats NOSE IN so I could use a little weight out back. Who else has run the older style 148mm setup, what else do I need? If it's not setback can I use my stock driveshaft?

Ratti's 145mm setup? I asked him about it and he said it worked great with his 1000cc XScream motor. Unfortunately it may already be sold.

Skat Trak mentioned some of the crazy Japanese guys are actually going to 155mm pumps! There is a 155mm skat Magnum on PWCToday right now.

Thanks in advance,

Aaron
 

IKSTEJ

BOGIE
Location
Region 7
I'm assuming your using a B pipe?
that big engine needs the big pump. 148 with a 12/17 or 13/18 should do the trick
of course you'll have to rejet when you get it to hook up.
Those are good problems to have :)
 
Thanks. I was hoping you would reply.

I'm using the old R&D pipe with a DASA Japan/Crazy House carbon fiber chamber. I also have water injection on it. It's pretty awesome. haha.

148mm it is then. So do I need to buy the $3400 skat trak setup, or can I get a used older style 2 piece 148mm pump and possibly a skat trak drive shaft?

What reduction nozzle, what trim/steering? I currently have Pro-Tec 144 stuff modified for lots of throw.

What pump shoe do I use?

Serious thanks for your time Pat.

Aaron
 
just look for the older gp 148's or find a 155 and send it in to skat and have them add the veins and liner to the housing.

if i remember correctly when impros repaired one for me the pump is 155 and only the liner is 148.
 

Waternut

Customizing addict
Location
Macon, GA
just look for the older gp 148's or find a 155 and send it in to skat and have them add the veins and liner to the housing.

if i remember correctly when impros repaired one for me the pump is 155 and only the liner is 148.

How much does that cost for skat to do that modification?
 
Location
dfw
You may be at the point where that big engine wont rev high enough for a 144 pump. Adding pitch works great when the ski is moving but just boils water when slow. Remove that TBM and install a stock concorde as a baseline. You will need to spin that over 7000 at low speeds in order to rule out the engine.
 

Cross

X
Location
WA
Try calling Randy at Watcon. Last week when I was at his shop, he had an older style 148 skat mag pump sitting on the bench. I almost biught it myself. Had good luck with it in the past
 

IKSTEJ

BOGIE
Location
Region 7
You should get the newer pump. I'm pretty sure we can do much better on the cost. hit me up next week.

What you really need is the 12 vane setback 148.
We had the same issue a few years ago on an 888cc
it spun the crap out of everything exept the 148.
Another option is to get the powerfactor pipe, and stay with the smaller pump. it'd be cheaper, and you'd extend your powerband 6 fold
just a thought :shhh:


Thanks. I was hoping you would reply.

I'm using the old R&D pipe with a DASA Japan/Crazy House carbon fiber chamber. I also have water injection on it. It's pretty awesome. haha.

148mm it is then. So do I need to buy the $3400 skat trak setup, or can I get a used older style 2 piece 148mm pump and possibly a skat trak drive shaft?

What reduction nozzle, what trim/steering? I currently have Pro-Tec 144 stuff modified for lots of throw.

What pump shoe do I use?

Serious thanks for your time Pat.

Aaron
 
We had the same issue a few years ago on an 888cc

Pat

What do you recommend for your 865 S set up ?? I though everyone is saying 12/17 Skat and TBM ??

Any advise ???
 

IKSTEJ

BOGIE
Location
Region 7
there are so many variables, like ignition, flywheel, carbs, weight of the ski, what grate, etc
that it makes it difficult to give exact info, but...
If your 865 setup is as we recommend, a hooker or skat 14/19 and a stock pump with tbm stuffer, will do it.
keep tweekin till it works :)




We had the same issue a few years ago on an 888cc

Pat

What do you recommend for your 865 S set up ?? I though everyone is saying 12/17 Skat and TBM ??

Any advise ???
 
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