ECeptor

I'm trying to calibrate my DT Dyno models. I cannot see how a Merc 330hp 454 can actually make 330hp. Maybe I have bad inputs to DTDyno. Maybe DTDyno is not accurate.

So, if anyone has actual dyno results for a 330hp rated Merc 454 (or 310hp at the prop fuel injected version) that data posted here would be greatly appreciated!

KAAMA

iTrader: (1)

No dyno sheets but something that might interest you is back in the early 1980's Ray Baker had done some dyno testing on the Merc 454cid 330hp engine and from what I remember him saying is that he usually found that they made much less than 330hp---usually within the 280-290hp range new....and that's with Merc's crude exaust system!

Another guy (Andy part owner) from "Jomar Engineering" told me about the same dyno numbers back then of the old Merc 330hp engine. He also said that the best dyno numbers they have seen on a brand new 330hp engine was 313hp but it was very rare from what they have dyno'd. They found most to be about 280-290hp back then---and much less than that when they were worn out.

ECeptor

Early 80's 454's would have had the large oval port heads, right? I didn't think the peanut ports showed up until mid-late 80's...

But the numbers you said seem to make sense to DT Dyno.

KAAMA

iTrader: (1)

EC, I would have to say "yes" to your question because of the time era of when I was told was when the larger ovals were being equipt with the 454"/330hp engines at the time. Back then I was asking a ton of questions and did a lot of research on how to "hotrod" the old Merc 330hp engine. I always thought it was imperative that to have a 4-bolt main block, steel crank, dimpled 7/16" rods, and large rectangle port heads, but of course it wasn't necessary for the RPM's we turn in a boat. While doing the mods we DID go with forged Speed Pro pistons.

*we kept the 2-bolt main blocks but had the mains align honed and used studs
*we kept the cast cranks
*we kept the 3/8" rods only we shot peened and resized with ARP rod bolts
*we kept the GM oval port 049 heads but mods were w/larger stainless 2.19"/1.88" valves, hardend seats, bowl/pocket porting, bronze wall guides, cut spring seats for diameter and valve guides for lift
*replaced the stock stamped steel rocker arms w/Crane Gold aluminum 1:7 roller rocker arms and went from 5/16" pushrods to 3/8"
*replaced the hydraulic cam w/the Merc 440hp grind *replaced the valve springs, hardend retainers/locks to match the cams
*replaced the cast pistons with forged Speed Pro pistons
*replaced the stock Merc non-breathing heavy cast iron exhaust manifolds w/GIL aftermarket exhausts w/dry pipes
*replaced the stock Merc cast iron "pancake" intake manifold w/aluminum hi-rise Edlebrock RPM intake
*replaced Rochester carb w/Holley 750cfm

Except for some items, we worked with most of what the 330 engines came with so, the blocks, heads and other parts that required machining were precision machined with accurate machine work and the rotating assemblies balanced.

Those 330's lasted for several hundred hours through many years in a 30' Scarab without the aid of oil coolers using Valvoline straight 40wt oil. WOT was about 5500rpm, but mostly crusied at about 3500-3700rpms. Rough guess on HP was probably about 450-475hp...which was pretty good out of a marine 454cid engine back then.

Of course we were much younger back then and we just didn't have a lot of money to dump into these engines, but was still quite expensive to us at the time. We especially dumped a lot of money in the heads, but GM heads were the only thing available and aftermarket heads just were nonexistant back then. Hope this is helpful.

Whiteknuckle

Kaama,
Yes Andy at Jomar was sort of an advisor to me when I first modified my 330HP. Andy is an advocate of staying with the peanut port heads, but cleaning them up and installing the larger valves. That is what I did, and the throttle response on the engine was great. My goal on the first phase was to hit 425 HP from the original 330HP engine. My son did all the work at Katech Engine Developement and the engine dyno'd on on the the Katech Superflow's at 422 HP. This was with cast crank, rods, ( with new ARP bolts) and hypernutectic pistons still running 8:1 CR.

After several changes including 049 heads and a cam I got from RMBuilder the Katech dyno had us at 540ft.lbs @ 3600 and 465HP at 4800RPM. There was still more to be gotten if we had the time, but they needed the dyno cell for something silly called LeMans for their GT-1 Corvettes.

KAAMA

iTrader: (1)

Whiteknuckle, I think one good thing about the "peanut port" heads is that I think they already have hardend valve seats that come from the GM factory---am I right on that??? Also, that is some good mod info you have added about the peanut port heads and the 049's and the power you have gotten out of them with a 454cid marine engine. I know you have had quite a bit of experience doing mods to the old Merc 330 and I think it is very helpful when you post...thanks for chiming in.

Whiteknuckle

Kaama,
Yes sir, the peanuts have hardened seats. All this messing around with the 330 to where it is now, was really not cost effective. But, it's been kind of a hobby with me and my son. He works on many high tech race engines but not much marine or big block stuff, so he is learning some of the suttleties of marine. I am of the opinon that about 450-475HP is a good figure for a 454 based NA engine that is easy to manage at the docks. There is nothing exotic about mine, however the most important thing I tell guys to keep in mind when doing the project is good machine work and good assembly.
Next phase--- Maybe a roller cam?

fbh-velocity

what flow numbers did you use? I try DTDyno with "360" Heads as this is the head what I found on most 454 330hp mk4. (330 hp at crank)

DTDyno make 322 HP@4500 and 326 HP@5000 404TQ@3500
HP Manifold with muffler.
The old log style manifold was very restrictive and some of them has only 3" riser. The newer center style manifold with 4 " riser doesn't choke the engine as much as the older one did. As long as you are below 4500 RPM I think you run out of cam / head-flow before exhaust in a´stock 330.

If you DTDyno the newer gen6 carburated 454 300HP (at prop) They had the even smaller "156" head that choke everything over 4500 rpm. They are only 115 cc and make actually 8.25 CR Best thing here is roller cam. 450 tq@3500
and 331 crank hp at 4500.
I dont think the HP rate is much off what mercruiser or other marine industries says.
Just my DTDyno run. Its not written in stone

ECeptor

Where did you get your 360 head flow numbers from? If you don't have a link, can you post the data here?

OR are you willing to email me the acutal DTDyno file...

fbh-velocity

http://users.erols.com/srweiss/tablehdc.htm