Hey guys I am a new boat owner but not new to turning wrenches and motorsports. I just bought a 2000 cheetah 21' open bow with a 250 hp 5.7 alpha one outdrive (pics comming soon). This is my first boat and I think its a good starter. With that said I cannot leave things alone and know Im gonna want some more power. I realize the alpha one can only take so much power so I figure I will start small and when its time to play with the bigboys I will upgrade the boat instaead of dumping a buch of money into this one. So heres my plan to start. Mild cam (maybe roller), edelbrock rpm airgap intake, vortec heads,600 to 650 cfm carb, and a drive shower. Any input is appreciated and welcomed especially on the cam choice.
5.7 alpha one upgrades
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I guess my question is, what are you hoping to gain? What speeds does it run now?
If I remember correctly the 5.7 up to 265hp was offered with the alpha1, the 350mag (265hp and up) and larger engines all came bolted to the Bravo1 or Bravo3.
I remember being told that the Alpha has not only hp limitations that are relatively low, but speed limitations too. The hydrodynamics aren't good above 65mph.
Not an expert, but just offering you a little heads up.
If I remember correctly the 5.7 up to 265hp was offered with the alpha1, the 350mag (265hp and up) and larger engines all came bolted to the Bravo1 or Bravo3.
I remember being told that the Alpha has not only hp limitations that are relatively low, but speed limitations too. The hydrodynamics aren't good above 65mph.
Not an expert, but just offering you a little heads up.
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:coffee-n-news:
OK.
First off, do not upgrade the camshaft with a flat tappet. Insist on a hydraulic roller.
Second, the Air Gap may not be my first choice, the major limitation (IMHO) on the Alpha drives is that they don't respond well to a bunch of RPM.
I would recommend building a stroker small block and using Vortec heads. Too much camshaft will hurt performance too (if trying to keep the power at lower RPM), so the torque numbers will need to be huge.
Maybe look into a Whipple charger or similar.
If the revs are kept in check (5200 and lower) the Alpha can live at 400HP without much drama, good oil and a drive shower are a must.
Just keep the WFO launches limited.
Hope this helps a bit.
Thanks for the response gents. Im not looking to set any records just a little more power out of the hole and some more top speed. As it sits rite now it does 50 no problem and will do 55 with smooth water I would be happy with 65 and still have a decent holeshot. I realize that the alpha has its limitations so when Im ready to play with the big boys the boat will upgraded (bigger boat) and not the drive. As far as cam and intake go am I wasting my time as I will not get alot of USEABLE horsepower out of them for the money or is it just be careful on my selection?
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dose it have through transom exhaust if its going through the hub that would be the best place to start
Yes sir :yes:
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My boat is an 89 mercuiser alpha 1 gen 1. i gained 12 mph going to a stock roller 350 with a xtreme marine 270 camshaft, vortec heads, edelbrock rpm aluminum intake and thru transom exhaust. i kept the stock quadrajet they are already 750 cfm. and a 21 pitch prop. in utahs high elevation(where it cant breath, two people, 2 full coolers and both tanks full of fuel i was getting 57 mph. never went past 43 on my old set-up.
I was running just a little past 5000 rpm. so i'm going to try to go up a pitch on my prop and see what that does.
the alphas do not like high rpm or to high of torque.
I was running just a little past 5000 rpm. so i'm going to try to go up a pitch on my prop and see what that does.
the alphas do not like high rpm or to high of torque.
Good info thanks.
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I would say that sounds like the best bang for the buck right there
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