Props RevisitedA

T

twhrider2

Junior Member
As mentioned in earlier post the prop that came on my V (I/O470) is a 14x21 WOT 3800rpm. Today I got a 14.5x17 alum. for free to try.
 
Oops.. to finish previous post. Does this sound like a good dia. and pitch to get my rpm to 4200? and if so is there a brand/style that is preferred for best performance?
 
They say you should get higher, I don't like running that high myself though, scared of blowing her up. I think the more important thing is to not lug the engine while cruising.
 
If the specs for your engine say 4500 WOT is ideal then yes, I'd think that a 14.5 x 17 was worth a try. Certainly don't want to over rev it, but you can always throttle back if you find that's happening.. then switch back to your old prop or try another one. Like Bradford said, it's more important to not lug the engine than to slightly over rev it.
 
that 3.7 doesn't mind to lug, if it were an outboard. I'd say prop it out to the top end of the rpm range, but the 3.7L is a torque engine, its doesn't like rpm, teh valve train really doesn't like rpm, prop it out to run around 4200-4500 rpm and you'll be fine. My old roommates 3.7 that I had hot rodded a bit turned 4800 and we had some rocker arm issues from time to time.
 
Thanks for the replies guys....If engine runs out good the rest of summer I have a complete 4 barrel setup to go on this winter along with a set of rollers to tighten up the top end and a little polishing just for sh*ts and giggles. Just more:money::money:
 
Prop performance on shakedown trip #3.

Prop# 14x21 stainless=3800rpm-30mph.
Prop#2 14.5x17 alum.=4600rpm-33mph.

Guess I will be looking for a 19p now huh?

Also waiting in line at dock this evening and lost forward on shifter..reverse is fine but no forward. Any ideas ? Shifter appears to be original '78. Oh and to make things worse Wifey smoked me fishing today!!! I love it.:beer::beer:
 
Picked up a used 19p alum. prop a couple weeks ago and ran great. 4300rpm wot & 36 mph in slight chop in a short run, engine sounded happy.
Bad news- got home checked prop and found a 1" crack in a blade oh well I guess the rompin stompin fire breathing 470 was more than it could stand lolol!!
Watching a couple of Merc. MIRAGE props on e-bay now. Just wondering about any advantage of the PLUS vs standard Mirage?
 
the plus has a little more slip than the standard Mirage and has cavitation holes to let it slip more from a stand still. The original Mirage will bog an outboard, where as a Mirage plus works fine on an outboard(thats the whole reason they came out with the Mirage plus)). From the specs you posted using an aluminum prop, I'd say you need a 17P Mirage,
 
twhrider2 said:
Thanks Spare....Now on the hunt for a 17p Mirage.
Click to expand...

And my 2 cents ain't worth a penney, but I'd make that Mirage 17 a LARGE diameter too...my Honda 150 spun a Mirage Plus 17p x 15.5" dia all the way up to the max 6,000 rpms w/no problem...I KNOW yours can use it...
 
You must log in or register to reply here.
Back
Top