How much HP do you think this engine makes?

[78Centurion]

I am new to all this and trying to figure out what this motor can do.
To determine what pump Impeller is best for a new rebuilt JG Berkeley I am going to install. With a Place diverter. Into my 1978 Centurion 18Ft Bubble with light Hull.
I think it has an A in the JC Berkeley now??
It pulls approx 5200 RPM with the old JC doing about 69MPH with good hole shot (Cavitation is bad if you jump on it from a stand still)
Engine made by Rex Hutchison in Sacramento
454 Block Blueprinted
Bored 70 over
Compression is 9.8 To 1
Isky Cam Z-55 RPM Range 3,500 – 7,500
(Solid Cam lift .338, Valve lift .590, Dur 254 (.050), Lobe center 108 & Lash .028)
Crank Stroke 4.00
Valves: Intake 2.190 Exhaust 1.880
Tunnel Ram with Two Vac Sec 1850Â’s 600 CFM each
Mallory Electronic Distributor

[Blown 472]

Whos dyno?

[67weimann]

148bhp...:D

[inwo]

148bhp...:D
Exactly :) No need to guess. ;)
.................................................. ............................
Really it's 440 @ 5200rpm.

[suckin&pumpin]

I am new to all this and trying to figure out what this motor can do.
To determine what pump Impeller is best for a new rebuilt JG Berkeley I am going to install. With a Place diverter. Into my 1978 Centurion 18Ft Bubble with light Hull.
I think it has an A in the JC Berkeley now??
It pulls approx 5200 RPM with the old JC doing about 69MPH with good hole shot (Cavitation is bad if you jump on it from a stand still)
Engine made by Rex Hutchison in Sacramento
454 Block Blueprinted
Bored 70 over
Compression is 9.8 To 1
Isky Cam Z-55 RPM Range 3,500 – 7,500
(Solid Cam lift .338, Valve lift .590, Dur 254 (.050), Lobe center 108 & Lash .028)
Crank Stroke 4.00
Valves: Intake 2.190 Exhaust 1.880
Tunnel Ram with Two Vac Sec 1850Â’s 600 CFM each
Mallory Electronic Distributor
i have a 77 18' centurion bubble and I added a cavitation plate and I have to tell you WOW what a diff the nose barely rises:D

[396_WAYS_TO_SPIT]

I am new to all this and trying to figure out what this motor can do.
To determine what pump Impeller is best for a new rebuilt JG Berkeley I am going to install. With a Place diverter. Into my 1978 Centurion 18Ft Bubble with light Hull.
I think it has an A in the JC Berkeley now??
It pulls approx 5200 RPM with the old JC doing about 69MPH with good hole shot (Cavitation is bad if you jump on it from a stand still)
Engine made by Rex Hutchison in Sacramento
454 Block Blueprinted
Bored 70 over
Compression is 9.8 To 1
Isky Cam Z-55 RPM Range 3,500 – 7,500
(Solid Cam lift .338, Valve lift .590, Dur 254 (.050), Lobe center 108 & Lash .028)
Crank Stroke 4.00
Valves: Intake 2.190 Exhaust 1.880
Tunnel Ram with Two Vac Sec 1850Â’s 600 CFM each
Mallory Electronic Distributor
Are you running water to your headers? If so that cam will NOT work!!!!!!! Way too much overlap! If you run dry, then your fine. Make sure that you tie both vac secondary cans together. YOu want to secondaries to open equally!
Ill take a long shot and say an honest 500hp.

[78Centurion]

i have a 77 18' centurion bubble and I added a cavitation plate and I have to tell you WOW what a diff the nose barely rises:D
There doesn't seem to be a lot of Centurion Bubbles. Where did you get the plate? Have any pic's?

[78Centurion]

Are you running water to your headers? If so that cam will NOT work!!!!!!! Way too much overlap! If you run dry, then your fine. Make sure that you tie both vac secondary cans together. YOu want to secondaries to open equally!
Ill take a long shot and say an honest 500hp.
The boat was set up with water and it seems to be ok. What can happen?
I want to run through transom Lightnings water jacketed soon.
I was thinking the HP was around 450 to 500. So the A impeller.
I plan on doing the Vac Sec link.
Thanks for the input.

[QuickJet]

The boat was set up with water and it seems to be ok. What can happen?
I want to run through transom Lightnings water jacketed soon.
I was thinking the HP was around 450 to 500. So the A impeller.
I plan on doing the Vac Sec link.
Thanks for the input.
When both the intake valve and the exhaust valve are open at the same time reversion can take place and suck whatever is in the exhaust (usually spent gas) back into the cylinder. When water is added to the exhaust it can get sucked back in as well.
Water doesn't compress and it will lock an engine up real quick destroying stuff on the way.
I've had cams bigger than yours and got away with it.

[suckin&pumpin]

There doesn't seem to be a lot of Centurion Bubbles. Where did you get the plate? Have any pic's?
I got the plate from a friend who had it in his garage, I have had a hard time finding out anything about old centurion except that they started in 1978 but my title says 1976 but first sold in 1977. I have pics but cant figure out how to post em LOL not good with computers more of a outdoor type.

[daddy b]

My long lost family! I thought I was the only one
1978 CENTURION :D :eek:
Well, you know what they say.... you can't always pick your family.:squiggle:
I run a aggressor A, I like it but have no speed or tach for numbers, good mid range pull.

[78Centurion]

I got the plate from a friend who had it in his garage, I have had a hard time finding out anything about old centurion except that they started in 1978 but my title says 1976 but first sold in 1977. I have pics but cant figure out how to post em LOL not good with computers more of a outdoor type.
Does the Cav plates look like this one in pic?
Just click Manage attachments and then Browse.

[suckin&pumpin]

Does the Cav plates look like this one in pic?
Just click Manage attachments and then Browse.
I only have the center plate but yes looks the same, and even though I am pretty much still a stock 460 the nose doesn't rise more than a foot.
My old sleekcraft, you would have to damn near stand up :P

[78Centurion]

I only have the center plate but yes looks the same, and even though I am pretty much still a stock 460 the nose doesn't rise more than a foot.
My old sleekcraft, you would have to damn near stand up :P
OK....... I thought you had more than the center plate. I have a short center plate also. Some thing is wrong with my setup.

[suckin&pumpin]

[QUOTE=78Centurion;2584748]OK....... I thought you had more than the center plate. I have a short center plate also. Some thing is wrong with my setup.[/QUOTE
Do you have that narrow "bat-wing" rear?

[daddy b]

Is your ride plate set too high, my boat will also ride very flat with just a bit down to the plate. I brought it up to ride better in heavy waves but it still does not come up much and takes a perfect set. Maybe the motor was put back in too far back. Measure from the back of engine to the transome.

[78Centurion]

[QUOTE=78Centurion;2584748]OK....... I thought you had more than the center plate. I have a short center plate also. Some thing is wrong with my setup.[/QUOTE
Do you have that narrow "bat-wing" rear?
See Pic.

[daddy b]

If the back looks like this, these boats are known for running a bit wet most of the time. Take a look at the bottom straight on and see if the plate is up or down, hard to see in your pic but if it is up, it will ride high until it gets moving.

[suckin&pumpin]

I have a jacuzzi, great f^&n design!

[78Centurion]

Is your ride plate set too high, my boat will also ride very flat with just a bit down to the plate. I brought it up to ride better in heavy waves but it still does not come up much and takes a perfect set. Maybe the motor was put back in too far back. Measure from the back of engine to the transome.
I will check the engine mount to transome since I took the engine out.
But Get this!
I Just got done splitting open the pump tonight. :sqeyes: The A impeller is cracked and missing pieces. I think I got luck by not having it explode on me. The cavitation has to be from the holes in the impeller. The bowls damaged also from the pieces being slammed out.
I was still doing 69MPH with this thing..............

[suckin&pumpin]

http://groups.msn.com/martinoboat/boat.msnw?action=ShowPhoto&PhotoID=4

[daddy b]

I will check the engine mount to transome since I took the engine out.
But Get this!
I Just got done splitting open the pump tonight. :sqeyes: The A impeller is cracked and missing pieces. I think I got luck by not having it explode on me. The cavitation has to be from the holes in the impeller. The bowls damaged also from the pieces being slammed out.
I was still doing 69MPH with this thing..............
Just wait till you get a good pump and impeller:D The power you have will put you near 80 mph. JUST DO NOT TURN WHILE WELL ON THROTTLE UNLESS YOU LIKE GOING BACKWARDS.:eek:

[daddy b]

http://groups.msn.com/martinoboat/boat.msnw?action=ShowPhoto&PhotoID=4
Nice paint, and yes they are the same except bbc with headers. Look how close the headers are to the side in my pic.
Is this the boat for sale on craigslist??

[suckin&pumpin]

Nice paint, and yes they are the same except bbc with headers. Look how close the headers are to the side in my pic.
Is this the boat for sale on craigslist??
yeah when I looked at the pics together i agree they are the same
I have a lot less motor though:sqeyes:

[78Centurion]

If the back looks like this, these boats are known for running a bit wet most of the time. Take a look at the bottom straight on and see if the plate is up or down, hard to see in your pic but if it is up, it will ride high until it gets moving.
I will look at the plate. If it is high to level should I lower it down a little?
I like your water shield around the back. Where did you get it? I had water pouring in one time.

[78Centurion]

Just wait till you get a good pump and impeller:D The power you have will put you near 80 mph. JUST DO NOT TURN WHILE WELL ON THROTTLE UNLESS YOU LIKE GOING BACKWARDS.:eek:
I think so too. :) See pic. What's your top speed?

[daddy b]

I really don't know the top speed, 468 @ 9:1 comp. oval ports, was running dual 450's but switched to 600's last week and I think that will help, I'm guessing 70-75 mph, because the hull is pretty light, and you know that is the HONDO pantera bottom on our boats and the brendella bubble deck.
My pump was cavitating but had it redone by Jet Boat Performance, Josh and Tom did a great job on it and that's where I got the splash after I spun out and ended up going backwards at @ 40mph (first day out and I learned my lesson), I highly suggest having one if you are anywhere around larger boats:D

[daddy b]

Hey how does that z-55 isky sound and idle???? I like the look of that cam.:rollside: I like the radical sound.

[78Centurion]

Hey how does that z-55 isky sound and idle???? I like the look of that cam.:rollside: I like the radical sound.
I get noticed when I start her. Splash guard wanted, who made yours.

[BrendellaJet]

Lots of these boats popping up lately. Any mods done to either boat?

[BrendellaJet]

Just to clarify the plate you guys are looking at is called a ride plate. Cav plates are typically found on V drives & are generally adjustable. Some jet boats have had them and the word is that this particular hull responds well to the cav plate setup. My Brendella has the recess for the plates from the mold so I will likely be performing this mod next winter.

[78Centurion]

Just to clarify the plate you guys are looking at is called a ride plate. Cav plates are typically found on V drives & are generally adjustable. Some jet boats have had them and the word is that this particular hull responds well to the cav plate setup. My Brendella has the recess for the plates from the mold so I will likely be performing this mod next winter.
The Cav plate in attached pic is what your talking about right? I plan on doing them like in the picture down the road. It looks like an easy Mod, but where to exactly place them I dont know???

[BrendellaJet]

The Cav plate in attached pic is what your talking about right? I plan on doing them like in the picture down the road. It looks like an easy Mod, but where to exactly place them I dont know???
That is a fixed plate, A little different than the cav plate. Picture that plate capable of adjustment from the drivers seat.
We have the same hull. Other Brendella's & Hondos Ive seen with this bottom had these recesses built in:
http://www.***boat.com/image_center/data/520/212100_0598.JPG
Here is a pic of the Hurry Round Hondo(same hull as the Brendella Bubble Deck, Centurion etc)
http://www.***boat.com/image_center/data/500/2864IMG_0854.JPG
The outer plates are adjustable using the pedals-it looks like they are adjusted separately-would need a hand throttle.
http://www.***boat.com/image_center/data/500/2864IMG_0855.JPG
Another shot:
http://www.***boat.com/image_center/data/500/2864IMG_0856.JPG
If Jet Novice see the pictures I posted of his boat, hopefully He can get us a pic of the inside looking at the linkage/hardware connections at the transom
http://www.***boat.com/image_center/data/500/2864IMG_0855.JPG

[78Centurion]

Nice!
I wonder if there is a easy way to adjust them without all the hardware?
I think a fixed (like the one I showed you) or something more basic in setup would be good for my use.

[BrendellaJet]

Nice!
I wonder if there is a easy way to adjust them without all the hardware?
I think a fixed (like the one I showed you) or something more basic in setup would be good for my use.
Why do you want them? Your hull should not need unless something is wrong. Do you have a place diverter?
I have seen systems with the locking hand control- lock in place at desired setting, and use the foot control as an override. There is a way to eliminate one of the pedals...Just have to tie both sides together- a little more difficult to do with a jet, but not impossible.

[BrendellaJet]

Before bolting a set of fixed plates to the back of your boat, buy a place diverter. A little pricey, but once you have it you will wonder how you ever lived without it.

[78Centurion]

Before bolting a set of fixed plates to the back of your boat, buy a place diverter. A little pricey, but once you have it you will wonder how you ever lived without it.
Thats the plan. Rebuilt my pump first then the diverter.

[watergun4u]

[QUOTE=suckin&pumpin;2584794]
See Pic.
I just wanted to let you know, that the plate on the back is a ride plate, cav plate are automaticly adjusted, a ride plate is adjusted by you and two wrenches, So 78centurion, what you need to do if your boat is porposing, you need to set the plate down, and that will inturn, push the nose down, But I am not understanding, why you want the nose to ride so low, it is best to get at least 3/4 of the boat out of the water and not be so sucked in, when it rides highier in the nose, it is so much a better ride, and will give you more mph, as well as rpm's, I am just putting in my .02 cents as I have built many jets and i/o's, I have built custom boats for over 26 years, So I have alittle insite on this, as far as your impeller size an A impeller is a good impeller up to about 450hp, anymore then that you can have major pump failure, as a pump set up from the factory is set up somewhat tight in the clearences,that more then 450hp, you stand a good chance of blowing up your pump. now if you where to go to an a/b cut impeller, and set the clearences up alittle loser, by maybe a couple of tho on each side. you will stand alot better chance of not blowing up your pump, I dont remember if you are running a diverter on not ,but if not that would help you control the ride of the boat, as far as being able to trim it out for the condision of the water, but the just my opinion, if you have any questions feel free to shoot me a email, or send me a post! email, boatdawgo@aol.com:D :D :D

[78Centurion]

A pic of my bottom. I resealed with marine Epoxy around the intake.