What is the most HP an Olds can make with stock heads

**455maveric** · 05-25-2010, 04:01 PM

first what are the best head are they C,A,KA or what and what is the bigest valves that can be instaled . Second what is the most HP that can be made with unported heads. third how fast will it be in a sleekcraft aristocrat with dropsnoot and jetovator and ride plate. I want to change the engine but for right now i want to go out on the lake and have some fun

**boatermike** · 05-25-2010, 04:10 PM

should be able to make enough power to get out and have fun. seems like 500 hp isnt hard to achieve but beyond that its tough. 50 mph is way more fun than not boating at all.

**455maveric** · 05-25-2010, 05:26 PM

i hope it would do more than 50 with 500 HP but the boat might be a big fat pig but it will be a prety pig

**OldSleekOlds** · 05-25-2010, 05:48 PM

These guys can give you a better answer to your Olds head question than most other guys. I think the "C" or "K" heads will get you the biggest valves. http://72.22.90.30/phpBB2/index.php?...6f159cee4c7be9

Which Aristocrat do you have? I have a 1976 Aristocrat tunnel with a 455 (462) Olds. They made the Aristocrat with either a tunnel or "V" bottom. Mine came with a Jacuzzi YJ pump. I did a conversion to an Aggressor pump with a Place Diverter. The pump intake is the original Jacuzzi that I reworked by machining it and adding a shoe and ride plate (I have a machine shop). I had a Droop Snoot on it but took it off because the boat goes better without the Droop. Maybe a straight Snoot would help, I never tried one.

I did a lot of work on the 455. It looks like this........

455 .....030 over = 462
Balanced rotating assy
Forged pistons 10.25:1
Edelbrock heads with extra porting
Harlandsharp rockers
Performer intake
Holly 930 cfm Marine carb
10 qt. oil pan
Restricters including push rods
Outside oil returns from rear of heads to pan
MSD ignition w/billet dist

Hardin log exhaust

I can supply cam specs and Dyno sheet if you want to see them.

The important part is the fact that with the help of 2 friends who have been building high perf. Marine engines for many, many years we could not quite get 500 hp. We made cam, carb, and intake changes. One of the friends has a Dyno in his shop. We tinkered with it on the Dyno for nearly 2 weeks. Taking the Performer intake off and installing a (port matched) new Victor intake actually lost more than 30 hp. The problem is the "Log" exhaust system. All of the Dyno pulls were with the exhaust system from the boat. RELIABLE sources tell me that the log exhaust was costing about 100 hp. The 2 guys working with me on it agreed.

What will you have for an exhaust system?

Unless you have a "good" exhaust system, you will have a hard time getting 500 hp out of your Olds.

**455maveric** · 05-25-2010, 07:13 PM

I have the V bottom it has a berk JE pump but i had a 2 piece bowl and a droop so i put them on with the jetovator i can lose the engine cover and go to thru transom headers

**OldSleekOlds** · 05-25-2010, 08:02 PM

I gotta think anything would be better than logs.

**boatermike** · 05-25-2010, 08:22 PM

i wonder if there are any gains if ya keep the logs but ditch the snails for over transom tailpipes

**boatermike** · 05-25-2010, 08:24 PM

5 ponies might go 70?

**boatermike** · 05-25-2010, 08:24 PM

stock tame would be better than nothing

**Raceman** · 05-26-2010, 05:27 AM

The absolutely positively BEST intake for a 455 olds is the old Edelbrock Torker. That's surprising because I don't think they're worth a crap for a big block Chevy. They're long since discontinued, but still relatively common on E Bay. Some of the dyno tests I've read in the mags claim 30 HP increase JUST FROM this intake over any of the other dual plane alum. intakes that are available. I've got an Offenhauser with 2 4's on my 455, but it's because I like the way it looks and it probably COSTS 30 or 40 HP. One of the mags............. Popular Hotrodding MAYBE has an olds buildup in this month's addition. Edlebrock heads, even stock, seem to be a big bang for the buck (under 2K from Summit)

**Hamjet** · 05-26-2010, 02:12 PM

Originally Posted by 455maveric

first what are the best head are they C,A,KA or what and what is the bigest valves that can be instaled . Second what is the most HP that can be made with unported heads. third how fast will it be in a sleekcraft aristocrat with dropsnoot and jetovator and ride plate. I want to change the engine but for right now i want to go out on the lake and have some fun

C,Ca and Ka heads are all big valve units. "A" heads I think are SBO units. The "C" &"Ca" heads flows the best in stock form as for the "Ka" units the two centre exhaust ports are not blocked off and drains hp.

IMHO in stock form you will be lucky if you get bejond 300Hp and that is with a good pump setup. 50-55mph on a good day.

It is fairly easy to check estimated hp by using your impeller chart (Berkeley).

If you know your impeller cut, let us say "A" and you know your RPM, you can calculate the hp range of your engine.

"A" impeller @ 4250 RPM will probably give you about 220-250HP for example.( above 4500 RPM they don't live long without special mods)

To get it to the 400-450HP range you are going to have to throw a wheelbarrow of $ at it, beyond 450-700HP a dumptruck full of $.

Wikus

**OldSleekOlds** · 05-26-2010, 05:38 PM

Originally Posted by Hamjet

C,Ca and Ka heads are all big valve units. "A" heads I think are SBO units. The "C" &"Ca" heads flows the best in stock form as for the "Ka" units the two centre exhaust ports are not blocked off and drains hp.

IMHO in stock form you will be lucky if you get bejond 300Hp and that is with a good pump setup. 50-55mph on a good day.

It is fairly easy to check estimated hp by using your impeller chart (Berkeley).

If you know your impeller cut, let us say "A" and you know your RPM, you can calculate the hp range of your engine.

"A" impeller @ 4250 RPM will probably give you about 220-250HP for example.( above 4500 RPM they don't live long without special mods)

To get it to the 400-450HP range you are going to have to throw a wheelbarrow of $ at it, beyond 450-700HP a dumptruck full of $.

Wikus

I agree completely.

Old