Loss of MPH
 

97 27 Fever 321 hours 502 Mag

When I bought the boat it would run 68 all day long. Ocassionally faster if all the stars aligned. This season the fastest I have seen is 63 (barely) and that is with 4 people full tank of gas and almost perfect chop to run in. I know its only 5 mph but now I am a little sluggish getting out of the hole. Oil pressure is still very strong and have changed oil and lower unit gear lube at the beginning of the year. I used to be able to hit the rev limiter easily but now, not so much. I think it is worth mentioning i have not changed props.

I have ordered a new fuel filter, distributer cap, wire ignition kit, rotor and spark plugs from BAM. To my knowledge they have not been replaced. I would be SHOCKED if the previous owner replaced them.

I have also noticed more smoke than normal when starting and burning 1/2 qt of oil every other fill up.

Also, I was thinking maybe sending my prop off at the end of the year to have it worked on. Any suggestions on that and do you think it is worth it?

I have ABSOLUTELY NO idea how well the boat was taken care of before I owned it so I don't know how hard (or not) it has been run.

Do any of you know if this could fix my problem or is that just part of the life of the motor? The factory paperwork says 68 WOT.

I am by no means a boat mechanic but have a friend that is very knowlegable and have been able to learn a lot from him just knocking around the garage. So anything too technical is WAY over my head.

Thanks for any and all input!

Your boat sit in the water a lot?

Only on the weekends. Saturday morning (occassoinaly Friday night) put it in and pull it out Sunday afternoon.

If I'm at the coast it comes out every day.

I have made one trip up the river to Chattanooga and it sat in the water for 3 days.

Also it doesn't stay near water like on a lift. It always sits on a trailer in the carport or warehouse.

Couple of things are you comparing apples to apples, at 68 was it loaded with a full tank of fuel and 4 people or not. I find it hard to beleive a 27 with a 502 would hit almost 68 fully loaded.

Either way 5mph could mean a alot of things, water temp might have a play, obviously conditions would, but fuel could be a factor, oil, prop had dings and dents in it. You could replace the things you are talking about but generally I dont think your going to pick up 5mph with all of that.

The boat is 15 years old, how many hours on it, and has it ever been rebuilt. If it has more than 4-500hours on it, its probably getting tired, which doesnt mean it needs to be replaced now, but just to watch it and if it gets worse stop running it.

Personally 1/2qt of oil every other time depending on hours might be a that things are going bad, maybe your oil pump is on the fritz which is kicking in more oil making the engine work harder. Also it MPI or carb, either way either of those could be dirty or need adjustment.

Really there lots of things to check, personally I would run it for rest of the summer, and this fall next spring have it inspected.

321 hours, never rebuilt, orginal engine, MPI, yes it would do 68 all things equal on GPS, actually the only time I saw faster than 68 was in salt water PERFECT conditions with only 2 people. I have only ran salt water maybe 3 weekends at the most. I'm 5 hours from salt so I don't get down there too much. ( I know the next question I will get is do I flush it, the answer is yes. I even run salt-away through before I put it in the water and then again when I pull it out. Maybe a little too paranoid)

I have a brand new water pump (housing, impeller everything) but I have not put it on the boat. I just have it "in case" if you know what I mean. I have never replaced it and never have seen that much difference in the gauge reading. While I'm in the engine compartment this weekend should I just go ahead and throw that on there as well? I have never done that job but doesn't look like a hard one from what I have read online and watched on youtube. I have TONS of room in the engine compartment! I hope one day thats not the case. :whistle:

Changing the water pump or impellor would have no bearing on MPH unless it is grossly overheating. With unknown history and 300+ hours, I would do a cpmpression test on each cylinder. If you have weak compression on any or all cylinders, you are losing horsepower and need to be considering rebuild/repower in future. Even if all in the 150 PSI range, good to have benchmark numbers for future comparision.

that would be my guess as well is your losing compression. You could have that tested now for free or fairly cheap to rule it out. Even if its getting bad, youll be fine rest of the summer. All the Maint things you are talking are good to do but like boats said unless any one of those things are grossly malfunctioning they are not a culprit of mass HP loss.

You switch octanes, maybe try some new gas with stabil. Also I know on my 454 87 gas runs better than premium on my boat.

Thanks for all your input. I will get a compression test done sometime. That is a good idea.

As far as gas goes, I run 87 "with no ethanol" but I still use stabil. The place at the lake advertises no ethanol but I don't think its the best fuel in the world plus you never know what kind of fuel the truck hauled before it dumped the "no ethanol" in the ground for this particular place.

Well if I'm able to get all these things done this weekend I will keep you updated but I'm not holding my breath and will continue to enjoy my boat.

I guess I need to start a "re-build fund" nontheless... not sure I am ready for the 35.....yet

It may be worthwhile to get your fuel tank to half or less which is about 35 gallons in your boat I think and run some fuel injection cleaner through it.

Also check underneath the hull to make sure you dont have a lot of buildup and its smooth, i know some guys claim that by waxing you can pick up a few mph. Also check all compartements and bilge for water. Every fountain Ive ever heard of cant seem to keep water out and the way they sit you cant always see the water. So maybe try tilting it up to make sure you arent carying a few extra pounds.

But with more oil consumption Im guessing compression like we said or your mpi unit is faulty/dirty and really being that old and hours its not uncommon for a tune up or rebuild.

But you should be fine to run just monitor everyhting and ensure you dont have a melt down as your rebuild could be significant larger.

Did you change oil filter or oil types this year.

If you lost 5 mph during winter storage, I would check for a hook. If the boat was winterized properly, I see no reason why it should be an engine problem. Just my o2

I did change oil types and filter this year from what was on it. Maybe a dumb question but would that be a big deal? For those of you who run 502 mag mpi, what do u use and recommend? I am very open to suggestions.

I wouldnt think as long as it was the correct oil and filter.

silly question did you go off of GPS both times or not? because if you are going by the boats gauge, then I wouldnt be trusting those numbers

HA! You mean those gauges are 100% accurate?:lolhit: If those are right I have about a 25 MPH Fever at WOT. Anyone interested? I am sure my PM's are going to be blowing up with offers....

I might have figured it out last night on a long ride home. Yes I am using GPS numbers, BUT I remember I replaced my GPS with a newer model that had chartplotting capabilities. On top of that it was a completley different company.

I would venture to say, maybe I have lost 1-2 or maybe 3 MPH and the other maybe be the difference in GPS unit used?!??! The previous unit was as old or older than the boat.

Still 5 MPH is a lot. If UPS gets here by this afternoon I will have more to report tomorrow evening hopefully. If I can just get 1-2 MPH back I will be a happy man.

This winter I will send prop off and get compression test to see about rebuild. I will just pay super close attention till the end of the season.

Just for my peace of mind, what does a quality rebuild cost? I wish money wasn't an object and I would be calling Young Performance (yesterday). I saw a couple core "trade-off's plus cash" in the classifieds. Does anyone have any info on those guys? Again any recommendations or input is greatly appreciated.

well it depends on what you have done but I would guess anywhere from 3-8k depending on where and what. I have a receipt from my 454s that were rebuilt and it was 13k for both. I cant remember what was all done. Your probably cheaper in doing a core swap if you can get the block minus being dressed for the right price, labor to take in an engine in and out shouldnt be more than half a day, and you could probably minimize that number if you pretty much un hooked a lot of it yourself.

Another way to test your GPS is run both at the same time and if you have a smart phone download a GPS app then run them, that should be able to tell you whats not working and what is.

But I think your expectation to get 1-3 back is reasonable, because I think on any given day your going to have some sort of deviation whether it be air temp, water temp, did you throw a bush light 30 rack into the cooler this time instead of moms favorite bartle and james 6 pack.

Another thing is how is your skeg and your lower drive, a few dents and dings can slow you donwn. My nose cones were kind of beat up. I went to walmart got the alumnium infused bondo and did them up and painted. dont even know there was something there and I picked up a 1mph.

A five m.p.h. loss would have to equal about an 80 h.p. drop. I don't see that happening "overnight."

I agree with Soldier4402. You can get a free speed app for your smart phone to double-check the accuracy of your new GPS speedo. You really will never have an accurate baseline unless you can compare your original GPS to your current GPS.

thats what i think too

It will be easy to run my old, new and my new iphone app at the same time.

Hopefully this entire thread will just be useless and a waste of everyone's time involved. :evilb:

whatelse do we have to do at work. LOL

Profound Statement

Never feel that your request for help is a waste of time. Everyone learns from problems that are solved.
The free app that I have on my iPhone is called Commander Compass Lite. It gives compass headings, elevation (for those really big waves we jump...), and of course speed. It matches my Vette's head up display and my Fountain's GPS. Good luck.

I hear ya.... This website is probably one of the best "investments" into boating I have made. The info on here is awesome!

Work done however weather did not permit boating today so needless to say shop is clean as a whistle. Fuel filter I got in the mail had a messed up gasket so I will have to wait on that.

Plugs were terrible, cap worse, wires replaced rotor ok.

Stay tuned

Id have to agree sometimes I feel stupid too, but let me tell you this website has probably saved me countless hours and or cash.

Theres a lot of things one can skip or not think of plus there are very knowledgeably people. I would like to think Im pretty good at figuring things out and have been around boats for a while, but performance is different ball game.