454 build criticism or opinions
 

So now that I have decided to put a big block back in my Bandit, let me know what you guys think of the potential build. The goal is to get the most out of what I have to work with already on the garage.

Brodix 312cc bb2 plus rec ports
22cc dome.030 pistons
Upgraded rods with tarp hardware
Hardin Marine Cam
Imco thumper exhaust
Edelbrock RPM Air gap
Quick fuel 750

Only other option I have is running mild ported 049 iron heads with 2.19/1.88 valves.

This will replace the peanut port 454.

A 454cid engine will most likely run better/stronger and you'll probably be happier with the results of the GM 049 castings vs a 312cc intake runner head.
Either way, you'll also be happier with using a dual-plane intake manifold (Edelbrock Air-Gap if you can) on a 454cid engine too. 👍
Just my .02

The rpm air gap I already have along with both heads. But it's for the rec ports. I do however get so many mixed opinions on heads.

I would try to swap the manifold with someone and go with the 049 heads. Guys have used the rectangular port intakes on oval port heads but it is not ideal. I agree that the Brodix heads are too much for a 454.

I would not waste my time and money putting ARP bolts in stock rods. By the time you are done you can almost buy a set of new Scat or Eagle rods and be better off.

The only problem with the 049 heads and the pistons you have is you are going to end up with too much compression for pump gas. I dont like to see any more than 9.5 to 1 with cast iron heads, prefer a little less. Thats with 93 octane fuel.

I have scat rods already with the arp bolts. I just neglected to mention it since they're just an I beam rod, nothing special other than the bolts.
I thought that the 049 heads were 122cc? Am I wrong? (Lots of conflicting info on the be web)

I usually try to stay around 9.2 with iron heads solely because you can never trust the fuel you get to be the octaine advertised and I dont like being too close to the edge just to gain a couple horsepower.

Most of the ones I have seen are closer to 118. If they actually are 122 then you will probably be ok. Only way to know for sure is to cc one of them.

Heads are one of of those things that are all over the map of opinions and suggestions.

But you can't escape physics.

What rpm are planning to cruise at?

What peak HP are you loosely looking to achieve?

049 heads will have better port velocity at part throttle cruise, but will likely limit the top end a little.

Brodix 312 are aluminum? I couldn't fine mention of iron versions. The Brodix heads flow way more in the exhaust, as well as intake. 312s are not as big as the GM 088 Rec Ports that Mercruiser used on many of their Blue engines, and they have really poor int port floors and stifling exh port flows.

049 exh flow @0.400" 140cfm
088 ported exh [email protected]" 188cfm prob best 088 flow
Brodix 312 plus exh [email protected]" 187cfm
​​​​
The Brodix are the way to go. Better intake flow and way better exh flow. You're getting about 265 cfm @ 0.400".

Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software

You can use Larry Meaux's head flow chart to check them out.

What are the specs on the Hardin Marine Cam?

Did I miss what drive you have on the Bandit?

I like it. Cam specs would be helpful. I'll always opt for better performing aftermarket aluminum heads than stock iron.
I run Dart Pro1's at about 320cc on my 454's @ 585HP and 87 pump gas.

Being able to run 87 is always a bonus.

Pro 1 320s have a good exh port.

585 is respectable. What RPM?

https://cimg8.ibsrv.net/gimg/www.off...ea0edd0ffa.png
Here's the cam I'm looking at.

The Brodix heads are on my 489 that's currently in my 272. I have Dart pro 1s that are fully ported going on that next couple weeks.

The drive is a early version Bravo 1

As for this boat, cruising rpm will likely be around 3800-4200 rpm with the intention of going fast whenever the want is there.

They are 345's with manipulated runners (at Dart foundry) and ported to ~320cc.
5800RPM

Mine that I have are 310, 320 after the porting

My cams specs...
https://cimg4.ibsrv.net/gimg/www.off...486087df2b.jpg

Eric Weingartner has a video on the Brodix 312s.


They would benefit from a very mild cleanup even in just the chamber lip off the seats.

That's a healthy cruise rpm 3800-4200. Less of an issue for the larger ports.

The cam looks to be in the ball park @223° int.

The GM forged Mag marine engines would peak at 5200rpm with 224° single pattern flat tappets with 0.510 lift. Longer exh duration would keep the hp up a bit after the peak.

I've watched his videos and got the same info from him and cleaned up the chambers prior to putting them on my 489. If I remember correctly I believe he said that they were an identical head to the 088 casting with improved exhaust ports.

That should be an interesting swap. I would love to hear if it actually is an improvement. Are you changing anything other than the heads ?

I have a PP hurricane single plane intake, but I really want try it with the rpm air gap first. But here are the flow numbers done on a 4.300" bore. Thinking of adding 1.8 rockers to get my valve lift to .599" instead of .566 with the 1.7s.
https://cimg3.ibsrv.net/gimg/www.off...ef50c84336.jpg

Depending on how much time and energy you have I would leave it all alone other than the heads. Then you will know if they really did anything. If you change 5 things you never really know what helped and what didnt :( What kind of power do you think it is making now ?

990 head replacement. The 088 and 990 heads are likely fairly similar. Though the 088 exh ports are pretty rough, as well as the bottom of the int ports.

990 heads can be ported better than Brodix 312s as delivered, but will take the lead once they get some attention with cartridge rolls.

2.25 Int valves should help a bit from the 049s.

I've got 2 sets of new 088 heads that need some mild cleanup. It's amazing Mercruiser managed to get them to perform.

Mike Jones from Jones Cams is one of the best cam grinders around. $550 is a custom cam charge for Hyd Roller. He has a very extensive marine engine spec sheet to dial a cam in for your needs. Worth checking out to see what he says. He's on Speed-talk.com forum as well.

Custom Camshafts | Jones Cams

Honestly, I don't know. All I've gotten out of the 272 is 63mph and that's on par with 375hp 496 and 415hp 502s in similar years. I wouldn't mind changing the heads and see the gains. When I built the 489 I had high hopes and really would have liked to get 70 out of it, didn't think that was unrealistic, but here I am surrendering to maybe going for mid 60s. The cam in that is a comp designed marine, 242/248 .566/.566 and 9.85:1 compression.

I will definitely check him out. Id rather have something built around my setup. I just bookmarked his page.

You might be hurting intake flow with the small bore and 2.30 intake valve; a 2.25 would be better. If anything, you aren't really gaining anything with the larger intake valve unless you were going to rev the heck out of it (not going to do that in the boat).

Have you played with timing on the 489? And are you sure on the actual compression stated?

I run 2.30" and bore notching takes care of that issue.

Compression is 100% accurate, measured the head cc, I measured the piston depth, and had all the other info needed. My timing is currently at 38° wot and pretty much stopped there. My block I notched for the intake valve prior to assembling with the Brodix heads.

Bore notching is effective in BBC...with the over hanging heads on the bore + large valves.
​​​​​
Don't the Brodix 312s have 2.25 Intakes?

38° is def on the high end.

I was considering pulling out back to 36 and see if I gain any RPM, I just can't get past 5k rpm no matter what right now. I do run 93 to keep it on the safe side. The Brodix heads do have 2.25 intakes.

I am going to remove the single plane intake manifolds on my 482cid engines and swap them out for a a pair of dual plane air-gap intake manifolds... Those will definitely give a 482cid Marine engine a good kick in the pants. Single plane intakes are a little too sluggish for a HEAVY 40 ft boat only making peak power @5000 RPM.
If my 482's were going in a 32' boat then a single plane would work a little better depending on the combination.