speed on a 358 sonic
 

I just wanted to tell everyone my results, I have a 358 sonic with 496 ho in it, the boat would run 68 to 69 on gps. I removed the restitor plates and put 26 pitch props. the cruise speed went from 47 at 3600 to 53 and the top speed went to 72 mph.. I am very happy with the results I think I might try 26 labbed might be able to get another 1 or 2 mph out of it. What are the average speeds for a 358 with 496?? Is this good or can I get more???

Re: speed on a 358 sonic
 

I have a 358 with 525's and switched from 4 blade Bravo1's to Hydromotive 5 blades and picked up 2-3 mph. The 5 blades also made a drastic improvement in the handling of the boat. Madprops, what are the resistor plates that you removed and how do they effect performance.

Re: speed on a 358 sonic
 

So how fast are you running now ? and Cruise speed ?

Re: speed on a 358 sonic
 

82 mph @ 5200rpm's is the best that I have ran on top speed. I don't remember what rpm's that I was running at cruise speed.

Re: speed on a 358 sonic
 

I spelled incorrectly they are restrictor plates in the exhaust manifolds

Re: speed on a 358 sonic
 

how much effort is it to remove these resistor plates? 3-4 hours per motor?

Re: speed on a 358 sonic
 

I just spoke to my mechanic and he cautioned against removing these as these plates keep water from backfilling the motors

Re: speed on a 358 sonic
 

What size 5 blades did you go with ? and what size bravo's did you have ? I'm trying to figure out what the pitch difference is when you go to a 5 blade.

Re: speed on a 358 sonic
 

I have heard that as well but after removing the plates there is no way the plates woulf have prevented that, now the are use to prevent moisture but again I personally think that it will get in not matter what but I am not a mechanic

Re: speed on a 358 sonic
 

No it took me about 1.5 hour per motor

Re: speed on a 358 sonic
 

[QUOTE=HiPerf2000]What size 5 blades did you go with ? and what size bravo's did you have ? I'm trying to figure out what the pitch difference is when you go to a 5 blade.[/QUOTE


I was running 4 blade 30 pitch Bravo 1's prior to the Hydrmotive 5 blades which are 27 pitch.

Re: speed on a 358 sonic
 

regarding the back filling the motors without the plates, the 496 HO's only take in the water through the exhaust system to cool down the heat exhanger since they are closed coolant systems anyway....so I don't understand how they can really hurt the motros anyway? but I'll ask my mechanis again.