# Has anyone ran the 4S SS impeller in a 2S



## redrum (Mar 26, 2017)

I have a new-to-me 95 Merc 45 Jet with the stock aluminum impeller. I sharpened up the impeller, which had been severely defiled . It runs great but I wanted to get a stainless impeller for it. I didn't know the whole 4S cutback to the 2S impeller under the same part number. I ordered a new stainless impeller and I'm guessing it's the 4S style now. I don't want to run it if I may lose holeshot or over rev the engine with no added MPH. I'm very happy with the performance right now. I was thinking about returning the SS and just getting a new aluminum one from OBJ. I'll attach a picture of theimpeller if anyone can confirm that this is the 4S model, thanks.


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## LarryMc (Mar 26, 2017)

I haven't run the 4S impeller in a 2S motor so I don't know how it would perform, but I can identify your impeller for you. It's the 4S impeller. Below is the 2S & 4S side by side. 2S on the right.

Don't know if you would be interested, but I have a Wooldridge 4 blade SS impeller for sale in the Classified section.


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## handyandy (Mar 27, 2017)

buy a cheap tachometer off ebay and try it if it revs to high sell it rotus on here might buy it I know he has a 4s and might want a SS impeller for it maybe. I'd be curious to know how it runs on a 2s


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## rotus623 (Mar 27, 2017)

Hah, thanks Andy, you are darn right, I'd consider it if the OP doesn't want it.


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## handyandy (Mar 29, 2017)

redrum said:


> I have a new-to-me 95 Merc 45 Jet with the stock aluminum impeller. I sharpened up the impeller, which had been severely defiled . It runs great but I wanted to get a stainless impeller for it. I didn't know the whole 4S cutback to the 2S impeller under the same part number. I ordered a new stainless impeller and I'm guessing it's the 4S style now. I don't want to run it if I may lose holeshot or over rev the engine with no added MPH. I'm very happy with the performance right now. I was thinking about returning the SS and just getting a new aluminum one from OBJ. I'll attach a picture of theimpeller if anyone can confirm that this is the 4S model, thanks.



Did you try running it yet?


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## redrum (Apr 2, 2017)

handyandy said:


> Did you try running it yet?



No, not yet. I'm currently working on a Wetlander 3L kit.


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## Lil' Blue Rude (Apr 2, 2017)

The 4 stroke impeller will be fine in your 2 stroke. Might even be better considering you have the 52cube merc. I've got a friend with a 56cube omc and he's running a 4 stroke impeller and there's not much difference rpm wise maybe 200rpm nothing crazy that's going to over rev a stock motor. Plus the stainless will last way longer then the aluminum ever would.


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## redrum (Apr 15, 2017)

The results are in:

Aluminum 3 blade Impeller - 29.7 MPH @ 5,400 RPM
Stainless 3 blade 4S Impeller - 30.0 MPH @ 5,300 RPM

Not the results I expected but now I know. :mrgreen:


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## LarryMc (Apr 15, 2017)

I'm surprised that you got higher RPM with the aluminum 2S impeller than the SS 4S. When I first got my Mercury 4S 40 Jet, I tried both the 2S SS and the 2S aluminum impellers. I got around 4900 top end RPM with both. With the SS 4S impeller, I get around 5200 RPM. Guess the 4S just doesn't have enough power to turn the 2S impeller any faster.


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## mphelle (Apr 15, 2017)

All good information, it would seem that redrum got one of the old style ss impellers.


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## LarryMc (Apr 15, 2017)

mphelle said:


> All good information, it would seem that redrum got one of the old style ss impellers.



Don't think so, the photo that he posted shows a new 4S type impeller.


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## redrum (Apr 15, 2017)

I think my aluminum impeller is original. It has been ground on for sure. Here they are side by side. I bought the SS one new just last month. Im pretty sure it's the 4S model.

Hoping rotus will buy the SS one from me and I'll get that 4 blade from Larry then post the results.




Gotta say I'm extremely happy with the upgrade from the 50/35. Just better overall performance and the 3 cylinder sounds good


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## mphelle (Apr 15, 2017)

redrum, if your new impeller is still out, could you post a photo of it laying on it's side with the same orientation that LarryMc used in his photo. Thanks


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## redrum (Apr 15, 2017)

It's still in the pump now. It is in the first picture up top. Here are a few more pictures I have of it.


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## mphelle (Apr 15, 2017)

No problem, LarryMc shows impellers from two different suppliers and it's easy to see how much material has been removed from Merc's new casting.


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## mphelle (Apr 16, 2017)

redrum, I enlarged your photo to show that the leading and trailing edge of each vane are almost directly across from each other, just like the 2s. On the 4s, the trailing edge has been cut way back to allow it to spin easier. I believe you have an original quicksilver 2s casting which is why your rpm did not increase on your test.


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## Lil' Blue Rude (Apr 16, 2017)

mphelle said:


> redrum, I enlarged your photo to show that the leading and trailing edge of each vane are almost directly across from each other, just like the 2s. On the 4s, the trailing edge has been cut way back to allow it to spin easier. I believe you have an original quicksilver 2s casting which is why your rpm did not increase on your test.


This impeller is a 4s. Trying to compare rpms between a worn aluminum and a new stainless is kind of a apple and orange comparison. The worn aluminum will turn more rpms then it would stock because it's not getting the same bite since the leading edge is has been file back from repeated sharpening. So stock for stock the 4s stainless might have turned as many rpm if not more then a new aluminum.


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## mphelle (Apr 16, 2017)

Lil' Blue Rude said:


> mphelle said:
> 
> 
> > redrum, I enlarged your photo to show that the leading and trailing edge of each vane are almost directly across from each other, just like the 2s. On the 4s, the trailing edge has been cut way back to allow it to spin easier. I believe you have an original quicksilver 2s casting which is why your rpm did not increase on your test.
> ...



What information are you using to identify redrum's impeller as a 4s?


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## LarryMc (Apr 16, 2017)

Another photo of the 4s & 2S impellers side by side, 2S on right. It's seems apparent to me that the impeller shown in the photo that redrum posted is a 4S impeller.


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## mphelle (Apr 16, 2017)

Well, you can't have too many photos, (hopefully you aren't going by the finish that quicksilver uses), with your trailing edges fairly lined up, the respective leading edge of the 4s hasn't "rotated" into the picture. Gives you a feel for how much trailing edge was removed.

If you could get a photo of your 4s in the same orientation of his below, we could wrap up this post.


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## Lil' Blue Rude (Apr 16, 2017)

This is what I'm basing my conclusion on. Look at the distance marked by the red line and compare it to the pics of LarryMC's pics. It's a 4S impeller. I've seen the 4S impellers in a number of different finishes including freshly ground like they'd just finished grinding a 2S down  .


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## LarryMc (Apr 16, 2017)

mphelle said:


> Well, you can't have too many photos, (hopefully you aren't going by the finish that quicksilver uses), with your trailing edges fairly lined up, the respective leading edge of the 4s hasn't "rotated" into the picture. Gives you a feel for how much trailing edge was removed.
> 
> If you could get a photo of your 4s in the same orientation of his below, we could wrap up this post.



I can't get a photo in the same orientation without pulling the foot off my motor and taking the 4S impeller off the shaft and I'm not inclined to do that solely to settle an argument. Lil' Blue Rude's post above should be enough to convince anyone that redrum has a 4S impeller.

If redrum wants to go to the trouble to do it, a sure way to determine if he has a 4S impeller is to drop the impeller down into the liner and measure the distance down from the top of the liner to where the trailing edge touches the inside of the liner. A 2S impeller's trailing edges will be almost even with the top of the liner. A 4S impeller's trailing edges will touch the inside of the liner approximately 1" down from the top of the liner.


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## mphelle (Apr 16, 2017)

Really didn't see an argument here, just gathering information that might help someone on the forum. I frequent many forums and don't think I've ever had to ask for help for myself, just try to get people back on the road or water. I even spent some time looking for your 90/65. Anyway, good info on measuring the impellers in the liner, had no idea they would have such a difference in height.


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## LarryMc (Apr 17, 2017)

mphelle said:


> Really didn't see an argument here, just gathering information that might help someone on the forum. I frequent many forums and don't think I've ever had to ask for help for myself, just try to get people back on the road or water. I even spent some time looking for your 90/65. Anyway, good info on measuring the impellers in the liner, had no idea they would have such a difference in height.



My apologies for the argument comment, Apparently, I misinterpreted your previous post.


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## handyandy (Apr 18, 2017)

Larry is right about redrum's impeller it's a 4s one. Rude is probably right as well in that he would be fine running it. I now have larry's old 2s impeller he sold it to me. I can take more pics of it if someone would like as it isn't in my motor yet. Have to say thanks to larry for selling it to me. Said it was like new along with the liner he sold to me with it, and he wasn't lying looks like it wasn't even run at all, and he shipped it out quick. Wish mercury/quicksilver changed the part number when they changed the design and still offered both styles of impellers. I'm sure it would be more money than it's worth, but I wonder what it would cost to have a batch of 2s impellers made.


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## redrum (Apr 18, 2017)

Post some pics. That would always help. I'll try to do some measuring like Larry described.


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## mphelle (Apr 18, 2017)

Wow Andy, you really showed some patience on that one, you've been looking for that impeller for a long time. It will interesting to see your results. If you wouldn't mind taking a photo like redrum I'll add it to my collection.




I'll shuffle alongside the bandwagon until I see the same photo of the cutback quicksilver 4s.


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## LarryMc (Apr 18, 2017)

handyandy said:


> I'm sure it would be more money than it's worth, but I wonder what it would cost to have a batch of 2s impellers made.



A heck of a lot more than buying an aluminum 2S impeller from outboard jets.


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## handyandy (Apr 20, 2017)

LarryMc said:


> handyandy said:
> 
> 
> > I'm sure it would be more money than it's worth, but I wonder what it would cost to have a batch of 2s impellers made.
> ...



True but typically the stainless 2s impellers were good for a little more speed than the aluminums and last longer. Thanks for selling me yours and giving me a fair price I appreciate it. Larry is real stand up guy to deal with. Any dealers or anyone else with 2s stainless impeller that I could find was trying to gouge me for more than what a brand new 4s one cost, which I wasn't willing to give. I'll try to remember to take some more pictures of the 2s one this evening. I got a another 2s stainless one that was real cheap but it was pretty well wore out. I've used my tig welder to weld a bead along the outside edge and leading edge of the impeller to build it back up I still need to grind and file it all smooth to fit in the liner right it will be a lot of work. Basically I'm trying to refurbish the old wore out one like how it's done with inboard jet pump impellers. The impeller I'm doing it on was cheap enough and wore out enough I don't really care if it works out well or not. We'll see how it works out will be a little while before I can finish it lot of other crap keeps getting in the way that needs to get worked on more so than a impeller experiment.


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## handyandy (Apr 24, 2017)

finally remembered to snap some pictures of 2s impeller hope it helps


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## redrum (May 8, 2017)

LarryMc said:


> If redrum wants to go to the trouble to do it, a sure way to determine if he has a 4S impeller is to drop the impeller down into the liner and measure the distance down from the top of the liner to where the trailing edge touches the inside of the liner. A 2S impeller's trailing edges will be almost even with the top of the liner. A 4S impeller's trailing edges will touch the inside of the liner approximately 1" down from the top of the liner.



I had to take my pump off and remembered to compare the two impellers as Larry described. As you can see in the included picture. The SS impeller on the left sits down much further into the impeller than the 2S aluminum one on the right.


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## redrum (May 26, 2019)

Look what I've got! I bought another boat with a 2002 Mercury 60/40 jet. It has the Mercury 2 stroke stainless 3 blade impeller. I'm still running the 4S stainless 3 blade. I may do a parking lot swap comparison after the holiday weekend.


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## handyandy (Jun 10, 2019)

nice hopefully it isn't too wore out. I still have my old wore out one that I welded on sitting on my work bench, haven't gotten around still to trying figure out a good way to turn it back down.


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