Old vs. New gains in mph?

[Hallz]

Hey guys I was just wondering as to the gain I may see in my mph after the rebuild.
My old setup went 72mph average and a best of 74 mph. I have since rebuilt the motor went 30 over, raised the compression to 10.5 went with a slightly larger cam (Old JM-20-22) and will be adding OTT Headers and blue printing the pump. Any guess as to the mph gain I might see?
New setup
73 Wriedt \ Berkley jet \ 461 Olds 10.5:1 compression ratio \ Comp 276AH (276 \ 284 506 lift on a 110 LSA) \ 850 holly \ Torker Manifold.
Also any and all recommendations as to the setup are welcome (except for the swap to BBC one).
Thanks

[Keithb87]

Also any and all recommendations as to the setup are welcome (except for the swap to BBC one).
Thanks
Darn...... :wink:
What kind of HP are you looking for??????
I was told that after 80 MPH it will cost an average of $1000.00 per MPH after that.

[Hallz]

I am not as concernd about the HP as the the set up. I "hope" to gain around 75 horse realisticly. I figured if the pump was set up right along with the new motor 8-10 mph would not be to much to expect. I am hoping to get 80 - 82mph out of it, 85 would be AWSOME!
I just wonder what else it would take if the new motor was putting out 500-550 hp and the old one was only putting out around 425. Personaly I thought 425 was kind of low for runnning 70+
Once I get to that point I will think about what else to do. I have seen a few jets run nirtous but I have also been told that it causes to much cavitation.

[396_WAYS_TO_SPIT]

You mean your not happy with 75?????? Alot of people woul kill to have 75 :jawdrop: if its a turnkey olds I woul leave that baby alone an enjoy it! The more the ponies go up, reliability goes down!(well with a olds that is). Im not doggin the ols because I have one. i am just speaking the truth. i would pump all the money into the jet if it was mine;)
396

[Hallz]

You mean your not happy with 75?????? Alot of people woul kill to have 75 :jawdrop: if its a turnkey olds I woul leave that baby alone an enjoy it! The more the ponies go up, reliability goes down!(well with a olds that is). Im not doggin the ols because I have one. i am just speaking the truth. i would pump all the money into the jet if it was mine;)
396
Well I would have if I did not pump the bottom end dry and loose the motor. Thats why I made the small changes I did. Now I also restricted the mains added a hp pump (not HV) 10 qt pan and will probaly do the restricted pr's.
I am not sure what all Gardian marine did when they built it but they did it right the first time. It lasted 10 years with only 1 bottom end job.
I was SO close to converting to the BBC when I did the rebuild I just wanted to give the Olds one more try. It was a hell of a motor. The boat went through 3 diffrent owners and back to me on basicly the original build.
As for not being happy with 75,....it's hard to be happy with something that you have ran for so long and never improved upon. Plus I usualy have 3 or more people in it. So obviously it slows WAY down at that point, I would like High 60's - mid/low 70's with 600+ lbs in it (if possible)
Buy the time I lost the motor the boat was down to about the mid 60's. The previos owner tried to turn it into a fishing boat and tore up the pump with sand,... so after I got it back I drove it like I use to and durring the 4th I just let it all hang out on a local lake and there she went!

[LVjetboy]

"I am not as concernd about the HP as the the set up."
So what setup changes have you made? If your only change engine rebuild then you very well should be concerned with hp and at what rpm if you care about speed.
That said, if your old Olds was putting out a rated 425 hp and your new Olds a rated 500 hp and your drag point 72 mph, then you may gain about 6 mph or a top speed of 78 mph. Same conditions as when you measured 72 mph on the old engine of course.
What's your impeller size and old rpm's?
jer

[BigBoyToys]

I was SO close to converting to the BBC when I did the rebuild I just wanted to give the Olds one more try. It was a hell of a motor. The boat went through 3 diffrent owners and back to me on basicly the original build.
Talk to Fleetimus on the Banderlog forums and see what kind of a speed increase he got when doing the changeover from a BBO to a BBC......Maybe that will change your mind ;) I currently have everything you need for a changeover to a BBC including motor (Needs freshened) that I have for sale for $1800.00 for the complete setup.

[Hallz]

"I am not as concernd about the HP as the the set up."
So what setup changes have you made? If your only change engine rebuild then you very well should be concerned with hp and at what rpm if you care about speed.
That said, if your old Olds was putting out a rated 425 hp and your new Olds a rated 500 hp and your drag point 72 mph, then you may gain about 6 mph or a top speed of 78 mph. Same conditions as when you measured 72 mph on the old engine of course.
What's your impeller size and old rpm's?
jer
My old setup went 72mph average and a best of 74 mph. I have since rebuilt the motor went 30 over, raised the compression to 10.5 went with a slightly larger cam (Old JM-20-22) and will be adding OTT Headers and blue printing the pump. Any guess as to the mph gain I might see?
New setup
73 Wriedt \ Berkley jet \ 461 Olds 10.5:1 compression ratio \ Comp 276AH (276 \ 284 506 lift on a 110 LSA) \ 850 holly \ Torker Manifold.
I checked the old cam and it was actualy a 308 adv (234 @.050 lift) and .474 lift on a 113 LSA or better known as W-31 cam.
so with the new cam, +.030 bore, compression up 1.5 points, the new intake, carb, ign. and Headers and a light pocket porting & gasket matching of the headsand intake along with new spiral pollished valves with 10% undercuting of the stems and a few more things that are sliping my mind I "hope" to pick up another 75hp.
As for the impeller size, I honestly dont know. Before the pump went it was at about 4800-5100 just before the motor went it went wasspinning 5500 and WAY down on mph!
I would like to keep it around 5K even.