Old school l 88 454 mags, needing more HP
 

I have a stock formula 1988 292, with 454 mags. I would like to get better power and sound out of these motors. All I am interested in doing is maybe piston upgrades and cams possible heads if I need to. Trying to do it on a budget. Not looking for a ton of power but at least a lumpy cam to sound perform better, and better compression, anything more than what it has because they still run strong, but I think they are tired. Looking for suggestions, ideas?
Thanks

Might be a good idea to do a compression/leakdown test on them first, if they're "tired" then you might push them over the edge with trying to get more HP out of them. If the above is all good, maybe some fresh ignition parts, fuel filter, and a carb rebuild?

If you're on a budget, then a good running engine is way better than a blown-up one.

Exhaust is usually the first step since any flow increase made with cams/heads/intake is pretty much negated by restrictive factory exhaust. Exh alone can get out of budget quickly especially if it's times 2. Exh will however give you some of that sound you wanted.

Lumpy cams sound cool as hell, but if running wet exhaust, they can cause water to get sucked back into eng. If you want to go dry exhaust, then you can go lumpy to an extent, still need some good mid-range to get on plane.

High compression is a great power adder but since boat engs are always under a heavy load, detonation can be a serious problem if other mods are not done to support it. Also need to know if you can get high-octane on the water. May need to start carrying cans of octane booster around with ya.

Once you open up an old eng, things start adding up fast. Prices on every little thing have gone up.

There's a good chance you can change boats to something more like you wanted for less money.

Think Docs advise is right on.

"On a budget" to you may be significantly different than the real cost of doing it.

BTW, what outdrives do you have?? Early 454mags were paired with Alpha drives

x 2 on This . Both sentences. ^^^^

454 Mag engines come with all "the good stuff" from the factory...including forged pistons, steel cranks, square port cylinder heads and 4 bolt main blocks....A nice upgrade to Mag Engines is to bolt on a pair of Weiand 177 superchargers. Mercury actually did this to some of their Mag engines right at the factory and called them the "Mercury 525SC". they ran great, and were very reliable engines. Maybe freshen up your engines with rings, bearings, valve job, ect....and find a used pair of 177's and go have fun !!!!

Bravo one drives

I have Bravo one drives

The super chargers look like the way to go, but how about cams? Im probably not going to touch exhaust, but if I do tear them down definitely hone the. cylinders all new rings and bearings to freshen them up. Valve job. Those chargers are hard to find used.

I purchased a kit from Tyler Crockett to wake up my 454MAG. Cam, larger valves, and increased comp ratio by milling down deck of heads with new SM exhaust. Cost 7K but added- 90 HP to the motor, sounded great!

365 Mag engines have 224° single pattern FT cams with 0.510" lift. 115.5° LSA. Not a bad Supercharger cam.

They were 390hp at 5200 rpm at the crank.

The 088 Rec Port heads are less than stellar. Quite honetly you would be better off with wrmed over Peanut Port heads. 70s/80s PP heads vs the 90s Gen V style.

You have 0.095" domed piston. The piston quench decks are poorly cast and can vary in their 'flat' surface. Generally in the 13cc dome volume.

8.6 CR

They also used a firm mounted rocker stud system, where the lash adjustment would be in the pushrod sizing. Aftermarket rocker studs are available...but had 3/8" studs into the head...and 7/16" on the rocker threads.

The stock cast iron exhaust manifolds can flow a reasonable amount of air. At 2.2cfm per hp unrestricted, they allow for about 415hp. Anything more than that they'll be a progressive restriction the more you ask from them.

Small SCs will heat up your air more at higher airflow. You can get diminishing returns very quickly.

If you SC....a quick bore hone (0.001" more) and re-ring would open up the piston to bore a bit for the extra heat expansion.

Valve health is another story. Re-building the rec port heads won't be cheap. Going to an aftermarket 290cc alum head ($1500 ish bare+ good parts) would go a long way to solving your problems. SCs + setup are not cheap, and you'll use more fuel per hp than NA.

wouldnt 1988 mk 4 454s have normal rocker studs, not "firm" non adjustable 3/8 thread ones ones as you mention?

Yes sir.

Smitty, that's right. For some reason I ended up thinking it was a '92.

If you are not going to upgrade your exhaust, you are wasting your time. You can't do any decent cam upgrade without upgrading the exhaust. Exhaust is building block #1.

Yes but exhaust is expensive and almost as much as a used set of 174 superchargers, but yes I get it.

You can push extra ait into the cylinders while compressed, but that extra volume needs to be evacuated through the exhaust. The restrictive pumping losses add up very quickly....to the point the SC may not add any power at all.

You didn't mention a HP goal. Very difficult to have success without specifying the goal and mission.

500hp, you're going to need some exhaust. The twins makes that reality a lot tougher for sure. Harder to find double used parts etc.

If your exh manifolds are any good at all...they'll have some value to re-sell...otherwise you need new ones anyway.