new engine for my 2750
#1
Thread Starter
Quent
Joined: Oct 2004
Posts: 238
Likes: 0
From: Loudon, TN
Eric Betty is in the middle of dynoing my new engine at 6:00 DST today. He is having to write the program as he goes so it has been a slow deliberate process this afternoon. Right out of the box the engine made 1014 ft lbs of torque at 4000 rpm. At 4900rpm the corrected hp was 978 and 5 lbs of boost. (The dyno room is over 120 degrees).
Eric is letting the engine cool and will do some more pulls up to 6000 rpm. He is excited about the possibilities as am I. The final goal is 8 lbs of boost so we will see. He will video the final pull and I will try to post it.
Seasoned Dart Big M
4.56 x 4.25 555Cu in
Howard Crank
Howard Rods
JE Pistons static 9.2
AFR Heads CNC ports and Chambers
4.0 Whipple
MOAC
Eric is letting the engine cool and will do some more pulls up to 6000 rpm. He is excited about the possibilities as am I. The final goal is 8 lbs of boost so we will see. He will video the final pull and I will try to post it.
Seasoned Dart Big M
4.56 x 4.25 555Cu in
Howard Crank
Howard Rods
JE Pistons static 9.2
AFR Heads CNC ports and Chambers
4.0 Whipple
MOAC
#5
Thread Starter
Quent
Joined: Oct 2004
Posts: 238
Likes: 0
From: Loudon, TN
The engine made 1078 at 5800 rpm. The interesting thing is how flat the torque curve was. It will probably be a drive breaker. I will try and get the dyno sheet posted. Quent
Last edited by Quent; 06-04-2012 at 05:05 PM.
#9
Thread Starter
Quent
Joined: Oct 2004
Posts: 238
Likes: 0
From: Loudon, TN
Guys, I want to see the final setup as well. I have been traveling a lot as Eric has worked on the boat. He is putting the engine back in and will be testing the boat this week. I hope to get the boat this weekend. Eric and I have talked on the phone 2 or 3 times during the dyno run and he will get me the sheet which I can post.
He was very pleased at the flat torque curve and how the engine pulled all the way to the 6200 rev limit. The boost was at 7.5 pounds and he left the fuel fat so I could go to a smaller pulley and get more HP. With the addition of the box and 1:36 gears, I probably will have more than I should. We shall see. Quent
He was very pleased at the flat torque curve and how the engine pulled all the way to the 6200 rev limit. The boost was at 7.5 pounds and he left the fuel fat so I could go to a smaller pulley and get more HP. With the addition of the box and 1:36 gears, I probably will have more than I should. We shall see. Quent
#10
Thread Starter
Quent
Joined: Oct 2004
Posts: 238
Likes: 0
From: Loudon, TN
Do any of you Lavey guys have a 2750 with a box. If so, where is your prop shaft relative to the bottom of the boat? I just had a Stellings box put on my Mid Cuddy Bow Rider boat with an SCX upper and SC lower. The prop shaft is about 1 3/4 inches below the bottom.
Recognizing that the SCX is about 3/4 inch further back than a Bravo or SC, is my height about right? I am effectively back 12 3/4" from where I was and at that time my prop shaft was about 2" below the bottom. Chris at Lavey told me today that about 2" below the bottom was correct. Once I have gone back 12" plus the additional setback of the SCX it seems that a little less than 2" would be about right since the water comes off the bottom of the boat at about 15 degrees. This certainly is no exact science and I am willing to tweak. I just need a good starting point. Thanks, Quent
Recognizing that the SCX is about 3/4 inch further back than a Bravo or SC, is my height about right? I am effectively back 12 3/4" from where I was and at that time my prop shaft was about 2" below the bottom. Chris at Lavey told me today that about 2" below the bottom was correct. Once I have gone back 12" plus the additional setback of the SCX it seems that a little less than 2" would be about right since the water comes off the bottom of the boat at about 15 degrees. This certainly is no exact science and I am willing to tweak. I just need a good starting point. Thanks, Quent




