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.