pre-impellers/inducers.. whats your oppinion

[chasinTail]

just looking for anyone's thoughs or experiences with pre impellers/inducers. any one see any real gains from them? is there a chance that it will hurt you in the top end? is it snake oil? i think its worth doing.. there are a coupple who have told me their worthless? whats your oppinion? just trying to decide weather or not to get it done. thanks for your help -George

[Squirtin Thunder]

If you have the power, YES.
If you have a big boat, YES.
If you pull skiers, YES.

[chasinTail]

i have a 19' bahner thats getting a 671 littlefield blown 468 chevy motor going into it. i will not be towing any skiers.. projected HP between 675 and 800.. not sure yet what it will make.. not done with the motor combo.. might also be running nitrous ontop of the huffer......

[Squirtin Thunder]

i have a 19' bahner thats getting a 671 littlefield blown 468 chevy motor going into it. i will not be towing any skiers.. projected HP between 675 and 800.. not sure yet what it will make.. not done with the motor combo.. might also be running nitrous ontop of the huffer......
I would definately go with it !!!

[SmokinLowriderSS]

The inducer helps to draw water into the suction housing as well as feed the impeller. Maybe it'll cost a couple MPH on the top end but then so will cavitation if your feeding isn't quite sufficient. May also help gain a couple by improving feed accross the impeller face. I think they are most important for acceleration with big HP motors and big impellers (especially bigger than an "A") I know 1500HP drag racers running them so they have SOME value in the mix someplace.

[steelcomp]

I would definately go with it !!!
why would you definately go with it??

[steelcomp]

If you have the power, YES.
If you have a big boat, YES.
If you pull skiers, YES.
How does an inducer benefit those three conditions? Are those thr only conditions that you would recommend an inducer?

[Duane HTP]

The pre-impellers are a very good piece in their place. To put one in a near stock HP unit would probably be a waste of time and money unless it was a real heavy boat. A heavy boat has a tendency to vacuate the pump throat before it can begin to move fast enough to refill it. There they are a big help. The other place for them is in a HIGH HP application. No matter how good your impeller and set up is, with a good high HP blown motor, you can cavitate the pump off the line. In this application, they are almost a must.
The only time I have ever seen one hurt top end was when it caused the pump to load better, thus lowering the rpm a little. In this situation, one can retrim the impeller to run at the desired rpm and regain every bit of your mph back,if not more. Also, it becomes necessary on some boats to open up the nozzle just a little when the inducer is put in to handle the extra amount of water it could cause your pump to handle. My experience with over 100 installations have all been good. Yes, I believe thay are a good deal. My .02.

[Cs19]

My opinion is some boats need em, some dont. There have been boats that ran them with no gains whatsoever at the races, but Im thinking the average river racer cant go wrong with one.
I still plan on testing one, along with 5000 other things.

[Squirtin Thunder]

why would you definately go with it??
Because neutral sucks !!!!

[Jake W2]

Jim you even run an inducer? :rolleyes:
Jake

[Squirtin Thunder]

Jim you even run an inducer? :rolleyes:
Jake
Jake it is like this before I had Jack at MPD do my inpeller work I could have used it. Now that Roostwear has my inpeller and I am running a stock A2 I am in need of a inducer. It seems Jack at MPD has the magic touch. Steelcomp knows this also first hand !!!!

[bp]

The pre-impellers are a very good piece in their place. To put one in a near stock HP unit would probably be a waste of time and money unless it was a real heavy boat. A heavy boat has a tendency to vacuate the pump throat before it can begin to move fast enough to refill it. There they are a big help. The other place for them is in a HIGH HP application. No matter how good your impeller and set up is, with a good high HP blown motor, you can cavitate the pump off the line. In this application, they are almost a must.
i've gone into this a bit before, but to amplify.
picture the boat at max rpm just off of a dead stop, hull still in the water (intake is still surrounded with water, no way for air to enter the intake), and all the water in the suction housing is blown out of the back of the pump faster than it can be replaced by forward motion and atmospheric pressure. at that moment, you have less than atmospheric pressure in the suction housing, and rapidly decreasing. the only way that pressure can increase is for the boat to speed up, and external pressure to overcome the negative pressure (atmospheric remains the same, engine still running). if you have a heavy boat, speeding up quickly is sometimes difficult. if you have a whole lot of hp, well, you can blow the pump away no matter how heavy the boat is.
when the pressure in the suction become seriously negative, the pressure at the eye of the impeller becomes even more negative, to the point that saturation pressure is reached, and water molecules can change phase to gas with the slightest release of energy.
the purpose of the cavitation reducer is to provide a little additional force to those remaining water molecules, and attempt to increase the pressure at the eye of the impeller, thus elevating the water above saturation pressure at the eye of the impeller, keeping the water in liquid form a little longer so the boat will go forward a little further recovering suction pressure. that's the physics concept. does it work? dam right it works.
The only time I have ever seen one hurt top end was when it caused the pump to load better, thus lowering the rpm a little. In this situation, one can retrim the impeller to run at the desired rpm and regain every bit of your mph back,if not more. Also, it becomes necessary on some boats to open up the nozzle just a little when the inducer is put in to handle the extra amount of water it could cause your pump to handle. My experience with over 100 installations have all been good. Yes, I believe thay are a good deal. My .02.
i haven't tested without it, so cannot comment. my only experience with loading is if i'm seeing too much pressure, less shoe, not enough, a little more. of course, that's balanced with whatever nozzle i'm using at the time.
i agree. wouldn't want to run without it.

[steelcomp]

What kind of improvements are gained by having the inducer detailed? Are they worth the extra cost if used out of the box??

[sdpm]

i haven't tested without it, so cannot comment. my only experience with loading is if i'm seeing too much pressure, less shoe, not enough, a little more. of course, that's balanced with whatever nozzle i'm using at the time.
Hey Brian, what pressure was too much or not enough? Do you have a Data Recorder? If so, how many taps are in your intake and pump? Me and Jeff B. got into a pretty good discussion about this. I also talked to Jack M. about the inducer and he said that they tried one on Jerrys boat and he said that it didn't help or hurt. We never tried tried one on our boat so I can't say. I do know that our boat and jerrys boat are no way similar. What works on a CP does not work on a Daytona especially with a 5* intake!!! Neil

[steelcomp]

Steelcomp -
Just what did you have in mind when you asked: "What kind of improvements are gained by having the inducer detailed? Are they worth the extra cost if used out of the box??"?
Hey Jack,
Good to hear from you.
I was told that the inducer could be "detailed" like an impeller, and was wondering if a guy was to spend the $$ for one, would the extra work be worht the extra $$. I don't know what "detail" an inducer means, and haven't had a chance to ask J. McC. what the improvement would be. I know what the improvement is with having an impeller detailed.
Your thoughts?
Edited to add:
I misspoke my question above on my original post. It should have read, are they worth the extra cost if used out of the box, without being detailed?

[NELSON#109]

I Have One In My Cp Tunnel. It's Off The Shelf, No Prep. I Have Never Run The Boat W/ Out The Thing, But It Has Run W/ The Same Set Up... Pump, Engine, Ect. I Know The Numbers It Ran Before, And I Know What Its Running Now. It's A Bitch Outa The Hole. Im Not Convinced It Has Made A Big Difference In My Boat, But I Dont Think It's Hurting It. With Some Changes In Set Up, It Might Help.

[sdpm]

Hey Nelson, do you use a delay box. It is very hard to try to throttle a light jet with a bunch of power at the starting line and be consistant. Leave at the exact same time every time and adjust the delay timer.

[bp]

i haven't tested without it, so cannot comment. my only experience with loading is if i'm seeing too much pressure, less shoe, not enough, a little more. of course, that's balanced with whatever nozzle i'm using at the time.
Hey Brian, what pressure was too much or not enough? Do you have a Data Recorder? If so, how many taps are in your intake and pump? Me and Jeff B. got into a pretty good discussion about this. I also talked to Jack M. about the inducer and he said that they tried one on Jerrys boat and he said that it didn't help or hurt. We never tried tried one on our boat so I can't say. I do know that our boat and jerrys boat are no way similar. What works on a CP does not work on a Daytona especially with a 5* intake!!! Neil
neil, i only make pressure adjustments based on down track data, not launch data. i like to see no oscillations below 35lbs, so i like to see the average somewhere in the 40-50 range. i have seen pressure differences with the exact same setup at a different track, just due to differing water conditions. firebird is the extreme example.
i have one tap approximately 2 o'clock, even with the front of the handhole for the suction side, and one tap 180 degrees from the cooling port for the discharge side. there are a couple reasons i made the decision to only have the two taps when i first got this system. when i crewed with jeffb on risky business, we had 3 suction pressure taps and 2 discharge pressure taps, plus other keel pressure taps that we could move the suction pressure taps around to for occassional testing purposes. that was a racepak system that had a lot of other data on top of pump pressure. although interesting to analyze, after many races i would find myself drilling down to specific information between rounds, what i needed to know right then, to help evaluate what the boat was doing to prep for the next round. based on what i learned from 2 1/2 years on that boat, and from jeff and jack during that time, knowing what i would be doing with my boat, considering what it is, i felt the two taps would provide sufficient information to fit my needs. i still pretty much feel that way.
i think an inducer in jerry's pump would just be added weight, doing nothing more than slowing it down. keeping in mind that speed of the boat has a lot to do with suction head recovery, i've sat 20' away from that boat lots of times on the rope watching him leave, and there are very very few boats that leave like that thing does. it accelerates away from the rope unbelievably hard. when the tail clears the rope, it is hooked up and gone. there's no real way to describe it without being there. on the other hand, risky business routinely blew the pump away about 75' off the rope, recovered, hooked up right before the line and was gone. we never did fully correct that, and once we had (and we would have), the boat would have been quicker than the world record 7.81 it still holds. although kz had an inducer, we never got around to trying it, which may have helped, but there were other things going on there too. it would be interesting to know if mike miller runs one; i think his daytona is relatively light?
although i don't have near the power of either of those boats, my boat is way heavy compared to both. i've had the inducer in it for 7 years, and i could tell the difference from the first time i stood on it with it in there with the old tired 427.
i tend to disagree with jak. the primary brand out of the box is somewhat blunt edged and rough. considering it's purpose, the environment it will be operating in when it needs to fulfill it's purpose, i believe it needs to be blueprinted to be as efficient as it can possibly be in very low pressures. i don't have the ability to record negative pressure, but i can tell you that for a short period after the hit, my suction pressure is always below 0, then recovers. i know there's still liquid at the eye, because bowl pressure is still climbing, but i do not know how low it goes. and that's on the wall of the housing, not the eye of the impeller.

[cyclone]

bob- i have observed the intake pressure dipping to zero out of the hole in both the Ultra and the Rogers and yet the bowl pressure still climbs. My setup will not read below zero psi either.
I ran an inducer in the Rogers and I honestly couldn't feel a difference. the boat went quicker after having the impeller blueprinted but the inducer didn't seem to help much. Unfortunately I wasn't able to do a back to back comparison at the track with and withou it.
I had just as much trouble with cavitation out of the hole with my old MPD-prepped Berkeley pump in the Rogers as a I do now with the Aggressor pump i'm running in the Ultra. I dont have an inducer in the new pump but am considering trying it given the pump's tendency to cavitate with anything more that 1/3 throttle from a dead stop.
This is with a mildly worked AA impeller.
Once the boat rolls over its a rocket and is hooked up and accelerating hard all the way out the back door. Spins 6,600 rpm all the way down the track.
I've had people suggest everything from an inducer to a 9.5-inch bowl and AAA impeller to help the holeshot. For now I'm going to use the launch controller as a band aid, detail the impeller a bit more and then try the inducer again. Would like to crank up the boost but it would be a waste until i get the kink worked out of the holeshot.

[DeputyDawg]

Cyclone, are you also running an Aggressor impeller?

[UBFJ #454]

bob -
Quote: "i tend to disagree with jak. the primary brand out of the box is somewhat blunt edged and rough."
Where's the disagreement when I said:
"1) For a Lake Boat or River Racer, other than making sure the edges of the inducer blades and faces are sharp and smoothly shaped to a reasonable degree and everything is properly balanced, 'Out of the Box' is all that is needed."
???
If it's about: "On the other hand, 2)"
Then I can understand that.

[NELSON#109]

Hey Nelson, do you use a delay box. It is very hard to try to throttle a light jet with a bunch of power at the starting line and be consistant. Leave at the exact same time every time and adjust the delay timer.
SDPM, the last two races have been with a mallory super mag.. no delay, no launch control. i know the starts are hard, i've had to pedle it every time to get it going. i've been luck and my RT's have been farley consistant, but there is no way i can get it better w/out a launch control. i just havent had the time until now to work on a launch control.
as of last week, i've got a new crank triger ignition on the way, and some new hardware for the pump. the hard part about the ignition for me, is that im having to mix match msd parts to work with my set up. it's a ford, but many of the internal and external components are chevy parts. lots of crazy machine work. i have a chevy balancer and a ford block so i need parts from both kits. i also have a huge TFS tunnel ram, which wont allow me to use either ford MSD crank trigger distributor.... had to go with the small diameter billet & convert it.
the next race should be interesting, big changes.... hopefully i'll see some good results. i realize these things are hard to get out of the hole anyways, and that is why i decided to throw the inducer in it... plus it was nearly free. i still am not convinced it is helping me, but at the same time i dont think its hurting... ill take it out this winter and detail it, just for shits and giggles. im still working on hardware set up, and until i get that dialed, i wont say without a dought it does not work. i may be to far out to notice it.

[steelcomp]

Bob, you know my deal...would I be wasting time trying out my set up without one at this point?? What makes Jerry's boat leave so hard without an inducer? Can that be duplicated? Keep in mind that for now I'm still NA, although near 800hp, with a satinless BC by Jack, hopefully in the 6300 rpm range. If it's inevitable that I'll need an inducer, I'll just get one now and be done with it. With the blown alky motor, I'm assuming it's going to be mandatory, yet when you talk about Jerry's set up... :idea: ???
Jack...I got what you were saying about the detailing. I might go as far as to smooth things out as well. I would imagine position of the inducer has it's importance as well.

[steelcomp]

Jack...I appreciate your desire to always disect thnigs the way you do. None of us ever see completely eye to eye, but with guys like you, bp, Jer, and others, there's a lot of good stuff here,
Please check your pm's.

[Aduner2]

How many of you guys think the loaders you are using are causing some cavitation problems during launch? Would keeping the boat flat to the water during launch (maybe with a diverter) reduce some cavitation? I realize you need the loader at speed.

[NELSON#109]

center blockers do without a dought cause cavitation problems out of the hole. as the bow of boat rises, the blocker cuts off the flow of water to the jet, but..... once the boat sets..... the flow of water is back, and the blocker helps provide transom lift.... which frees the boat from the water, lets it get loose, and hopefully makes it faster.... ahhhhh the trade offs... i cant wait for that launch control. i need the blocker, but those 8,300 rpm revs are gonna start kickin those alum. rods out the bottom.

[pops1]

Inducer or Two Stage is same thing. What fits one's boat, is not the best for everyboat. Nothing can beat a well set up bottom load. Its a art of understanding' Yet cannot be duplicated same hull to next hull (same mold).
As a rule you are throwing 1300 GPM more at the Pump then it has in output.
So this builds reversion into the pump. In the case of a fine tuned unit that has a sound load established it tends to slow the ET and MPH#s down (reversion). In the case of underload units it picks the ET & MPH up.
Above is fact, yet will not answer anyones question as to the need or no-need condition. Jets just seem to want to work this way! 2-Stage or Inducer causes extream turbulance in the suction. Yet I have seen a the addition of a inducer or 2-stage fix a lot of bad problems,the same if you overload don't throw this on top of it unless you have spurrs.