271 speed
05-15-2006, 10:56 PM
#1
Registered
Thread Starter
Join Date: Nov 2005
Location: Athens, Alabama
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
271 speed
I would like to hear about mods to 271's and the results. I am looking for mods for a 502 mpi, such as cams, injectors,superchargers,ignition etc. Also like to hear about drive and prop mods.
05-16-2006, 06:40 PM
#2
Re: 271 speed
My 1999 271 Fastech gained 10 mph with a Whipple setup and a 26P 5 blade Hydromotive prop. I am still experimenting with props. Trying out a 28P Bravo lab this week.
An IMCO Powerflow exhaust did not noticably help in the performance category but they helped me shed about 80 lbs and look much better than stock.
An IMCO Powerflow exhaust did not noticably help in the performance category but they helped me shed about 80 lbs and look much better than stock.
05-17-2006, 12:33 PM
#3
Registered
Join Date: Dec 2005
Location: springfield, Mo
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
Re: 271 speed
I bought my 98 271 last fall & over the winter I had EMI thunder exhaust & a CP performance efi upgrade kit installed. Last fall the speedo would hit 66 & so far this year it hits 68-69 mph. As Grog ,I am currently testing props from throttle up. This weekend I will have a hydromotive quad IV 26p to test. So far the best speed I have seen GPS wise is 65mph with my 26p bravo 1.
I figure the exhaust was a good stepping stone to a supercharger & they sure look better than the cast iron stuff. If ya want to gain alot of speed real fast the supercharger is probably the route to take. One thing I just noticed on the procharger website is that they have a before & after spec of a 271 & to get the 17 extra mph they had to change the drive ratios. That's an extra expense I had never thought of.
Any way hope this helps & keep us 271 owners posted on your progress! Chris
I figure the exhaust was a good stepping stone to a supercharger & they sure look better than the cast iron stuff. If ya want to gain alot of speed real fast the supercharger is probably the route to take. One thing I just noticed on the procharger website is that they have a before & after spec of a 271 & to get the 17 extra mph they had to change the drive ratios. That's an extra expense I had never thought of.
Any way hope this helps & keep us 271 owners posted on your progress! Chris
Charter Member
05-17-2006, 01:58 PM
#5
Re: 271 speed
Chris -
I went to the Procharger website and geez....17 mph is quite an increase for 5lbs of boost. I would take that with a grain of salt.
In talking to Dustin Whipple before I bought my SC setup from him, his expectations were 10-12 mph. I ended up with 10-11 mph for ambient conditions mostly the same before and after the install. In my opinion, 5lb of boost is 5lb of boost no matter whether it comes from a Whipplecharger or a Procharger. I'm sure there are some differences in efficiency between the two and I know the power vs rpm curves are different but at WOT, I doubt the differences are that much. These are all rules of thumb that I have read in the past on this forum and I can't vouch for their accuracy but they seem to make sense. Here goes:
1) 5lb of boost @ approx 30hp/lb = 150 hp
2) Additional mph is approximately a squared function, so 144 hp additional would get you roughly 12 mph. For 17 mph you would need almost double the additional hp from the SC.
Maybe I am full of crap but nothing sucks more than the first time on the lake with $5000 in upgrades and your boat going 5mph slower than what you expected.
I'll say it again: Maybe I am full of crap because I am certainly no expert but 17mph seems a bit optimistic.
Greg
I went to the Procharger website and geez....17 mph is quite an increase for 5lbs of boost. I would take that with a grain of salt.
In talking to Dustin Whipple before I bought my SC setup from him, his expectations were 10-12 mph. I ended up with 10-11 mph for ambient conditions mostly the same before and after the install. In my opinion, 5lb of boost is 5lb of boost no matter whether it comes from a Whipplecharger or a Procharger. I'm sure there are some differences in efficiency between the two and I know the power vs rpm curves are different but at WOT, I doubt the differences are that much. These are all rules of thumb that I have read in the past on this forum and I can't vouch for their accuracy but they seem to make sense. Here goes:
1) 5lb of boost @ approx 30hp/lb = 150 hp
2) Additional mph is approximately a squared function, so 144 hp additional would get you roughly 12 mph. For 17 mph you would need almost double the additional hp from the SC.
Maybe I am full of crap but nothing sucks more than the first time on the lake with $5000 in upgrades and your boat going 5mph slower than what you expected.
I'll say it again: Maybe I am full of crap because I am certainly no expert but 17mph seems a bit optimistic.
Greg
05-18-2006, 11:48 PM
#6
Registered
Thread Starter
Join Date: Nov 2005
Location: Athens, Alabama
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
Re: 271 speed
Yes, I think 17mph would be very optimistic. The test I read showed the procharged 271 doing 79mph. That would be very nice, but I would be afraid of the factory steering!!!!!!!!!!!!!!!!!!!!!
05-19-2006, 11:28 AM
#8
NO WAKE ENFORCER
Platinum Member
Join Date: Mar 2004
Location: Dayton, Oh
Posts: 1,221
Likes: 0
Received 0 Likes
on
0 Posts
Re: 271 speed
Originally Posted by Bangin Bottom
Yes, I think 17mph would be very optimistic. The test I read showed the procharged 271 doing 79mph. That would be very nice, but I would be afraid of the factory steering!!!!!!!!!!!!!!!!!!!!!
MAN I WISH I HAD THAT PROBLEM (79MPH)
05-19-2006, 11:50 AM
#9
Platinum Member
Platinum Member
Re: 271 speed
Consider adding a good hydraulic steering system. The only feeling better than going 79mph is being able to control the direction of the boat!! 
ENJOY! ERIK
ENJOY! ERIK
05-19-2006, 11:53 AM
#10
Platinum Member
Platinum Member
Re: 271 speed
Originally Posted by Grog
Chris -
I went to the Procharger website and geez....17 mph is quite an increase for 5lbs of boost. I would take that with a grain of salt.
In talking to Dustin Whipple before I bought my SC setup from him, his expectations were 10-12 mph. I ended up with 10-11 mph for ambient conditions mostly the same before and after the install. In my opinion, 5lb of boost is 5lb of boost no matter whether it comes from a Whipplecharger or a Procharger. I'm sure there are some differences in efficiency between the two and I know the power vs rpm curves are different but at WOT, I doubt the differences are that much. These are all rules of thumb that I have read in the past on this forum and I can't vouch for their accuracy but they seem to make sense. Here goes:
1) 5lb of boost @ approx 30hp/lb = 150 hp
2) Additional mph is approximately a squared function, so 144 hp additional would get you roughly 12 mph. For 17 mph you would need almost double the additional hp from the SC.
Maybe I am full of crap but nothing sucks more than the first time on the lake with $5000 in upgrades and your boat going 5mph slower than what you expected.
I'll say it again: Maybe I am full of crap because I am certainly no expert but 17mph seems a bit optimistic.
Greg
I went to the Procharger website and geez....17 mph is quite an increase for 5lbs of boost. I would take that with a grain of salt.
In talking to Dustin Whipple before I bought my SC setup from him, his expectations were 10-12 mph. I ended up with 10-11 mph for ambient conditions mostly the same before and after the install. In my opinion, 5lb of boost is 5lb of boost no matter whether it comes from a Whipplecharger or a Procharger. I'm sure there are some differences in efficiency between the two and I know the power vs rpm curves are different but at WOT, I doubt the differences are that much. These are all rules of thumb that I have read in the past on this forum and I can't vouch for their accuracy but they seem to make sense. Here goes:
1) 5lb of boost @ approx 30hp/lb = 150 hp
2) Additional mph is approximately a squared function, so 144 hp additional would get you roughly 12 mph. For 17 mph you would need almost double the additional hp from the SC.
Maybe I am full of crap but nothing sucks more than the first time on the lake with $5000 in upgrades and your boat going 5mph slower than what you expected.
I'll say it again: Maybe I am full of crap because I am certainly no expert but 17mph seems a bit optimistic.
Greg
ERIK
