97 PQ 270 laser wt twin 350 mags to 383 400hp what kinda speed
12-09-2014, 07:59 PM
#1
Platinum Member
97 PQ 270 laser wt twin 350 mags to 383 400hp what kinda speed
im rebuilding my 350 mags right now to 383's
383 with about 400 hp is what my motor builder is saying
so im going from 520 hp to 800 hp
my question is what kinda speed increse should i expect.
out drives are alpha 1 1.5 ratio
props ss 25 pitch
it ran wide open at 4300 rpms with those props at 64 mph
also wondering if i would be able to get away with those props or should i start shoping. or am i going to have to wait till summer to and do testing first
383 with about 400 hp is what my motor builder is saying
so im going from 520 hp to 800 hp
my question is what kinda speed increse should i expect.
out drives are alpha 1 1.5 ratio
props ss 25 pitch
it ran wide open at 4300 rpms with those props at 64 mph
also wondering if i would be able to get away with those props or should i start shoping. or am i going to have to wait till summer to and do testing first
12-09-2014, 08:17 PM
#2
Registered
iTrader: (1)
Well if wide open was 4300 that was a little low on the 350 mags. All depends where you'll make peak power. These 383s gonna be dynoed so you know right where to prop it? If its in the mid 5s those 25s may end up being right as it was seemingly over propped with the 350s.
12-09-2014, 08:43 PM
#3
yes it was over propped for cruseing purposes. i bought a set of 22 pitch props and it went to 5k rpms and lost 5 mph so i just stuck with the 25 pitch props and i was thinking about dynoing the engins for break in purpeses and to know hp
12-10-2014, 08:45 AM
#4
Registered
iTrader: (1)
Dyno is the best way. Get peak numbers. Make sure everything is running right with no leaks. A lot easier to fix a small mistake on a dyno rather than in the boat. I think your 25s will be a good start. I had a 272 formula twin smallblocks with alphas. Ran 23s 3 blades. All day any day was 57 mph around 4600. Best of 63 with right load and conditions.
