MYSKATER32

My blocks are 12 years old,fresh water only,and show no signs of corrosion at all.The trick in a marine environment is controlling all your temp.Without control the water and oil would never get above 90*so you have to use restricter plates and thermostats in the water system and oil thermostats for oil temp control.Condensation is the biggest problem with the cold alum block ,but is easily controlled by keeping the oil temp above 185 with the thermostats.The one really good feature of alum is if you drop a valve or something and loose a cyl ,you just replace the liner,not through the whole block away !

bcarpman

I don't know what a Donovan Alum block weighs, but over the years aluminum blocks have ranged from 98lbs to as heavy as 157lbs. This will save anywhere from 100 to 160lbs over an iron block.

On a 30ft with 600hp BB's that's about 2mph. Probably not a bad compromise considering what two 600hp BB's cost in the first place. Probably less than 1mph on a high HP 40fter

I've never seen any direct comparisons for HP losses, but i would guess it probably would be a big deal once you go SC. Especially for longevity. I know guys that had Chevy factory sponsorship that could have any parts they wanted that still ran cast iron.

Alum. BBC's are certainly a different casting, but not a total redesign. If you look at a good dedicated aluminum racing block, you'll notice details like webbed pan rails that come down below the crank so that the caps bolt in from both the bottom and the sides. Also, split blocks with head studs that run all the way to the crank journals, etc.

Also, remember the high boost turbo F1 engines of the 80's. They were cost is no object motors were every gram counted and they were iron blocks.

articfriends

iTrader: (1)

I definately agree on the exotic,foreign and oem stuff that there is probably no drawback to a aluminum block as they have done there home work and research. My limited experience on aftermarket aluminum blocks is based on what a few engine builders have told me and the following personal experience. I used to own a extremely modified jeep that I used strictly for competition. It had a very well built 406 based on a stock gm block,had 5.7 rods,dart 220 cnc heads,dart wilson intake etc. It made around 500 hp but I was looking for more,I bought a set of 240 cc extremely modified heads,a 4340 crank,6.0 inch rods and a brand new dart aluminum "rocket" block small block. It had a raised cam tunnel,roller cam bearings and a funny pan rail style that required a custom pan. I paid 3800$ for this new block,sent it to Baker engineering in Nunica Mi who built me a custom oil pan and built themselves a jig to build future oil pans for their customers while I was gathering up the rest of the parts I needed. I considered having them do the final machine work on it,talking to them on the phone they told me they sucked to do the machine work on and that they were less than ideal to use for anything other than a sprint car running on alchohol but wouldn't say much else as to why. I decided against having them do the rest of the work because I wasn't getting a warm fuzzy feeling from them and was looking for perfection as it was quite a investment on my part at the time. I got the block back and after talking to the local machine shops I found none of them were confident they could properly machine it. They felt the best thing was to send it to a place set up to bore it while preheating the block with warm water so it would be up to operating temp (which really sounded like it was the way to go considering it was aluminum and I didn't want the sleeves loosening up or doing something funny while final boring it). On the advice of these guys and the experience of a nhra record holder team I do transmissions for I decided to send it to Vince Impastato racing down near detroit. I sent it down there and wrote out a detailed list of what I wanted done (it only needed to be final bored and honed and decked plus I wanted to have all the clearences checked while it was warm which might have been overkill but seemed like a great idea to me). After waiting 2 months of hearing nothing I got ahold of the owner of the place,Vince impastato. For twenty minutes on the phone he told me how these aluminum blocks were nothing but problems,wouldn't hold clearences while machining,gave up hp due to liners moving around and deforming,had serious head to block sealing issues when running a cooling system under pressure and for what I was doing I should sell the aluminum block and buy a cast iron block. He also claimed they had used the same exact block in a road race corvette and it had been a nightmare of problems.He also told me that it would be the fastest way to give up 20-40 hp and ring seal under 10% leakdown would be hard to achieve. He said the best use for it was to fill it up with hard block filler and run it in something with alchohol were you don't run a cooling system (which was what Baker had told me). I got it back from him with out having any work done and was back to square one.All I wanted to do was have a light 700 hp 434 that would run reliable. After it sat on the shelf for another 6 months in my shop I got the bug to buy a new,bigger boat (my current 27 ft baja) and sold it along with all the other components I had gathered for it for 10,000$ (to put on the boat as a down payment) to a local sprint car racer so I never actually ran it or finished it. I'm not sure if it was the brand it was or if these things even apply to big blocks but I am leery of trick,exoctic things now like aluminum blocks,Smitty

tomcei

Now your scaring me. I found what appears to be a nice set up. 60 hrs (used) 572ci 11:1 ( I was told it runs pump gas)
Has all kinds of top of the line parts: Jezzel shaft ,corrillo rods, lunati crank,solid roller,I think merlin heads, monster dominator carb, external oiling system with some $1400.00 oil pan, etc, etc, bla bla bla. It's supposed to make something like 800-hp @5800 and 900-@ 6500rpm
apparently built to spin like that. Does this seem feasable?

stevesxm

well... it seems a bit optomistic to me but if it is as good as he says and the price is right, then a day at a dyno ( not the guy that built it ) might give you the handle on a good deal. if the claims and condition can be validated, ... and i would do a leak down on the dyno when its warm... then how can you hate it ?

MYSKATER32

Those figures are very feasable,it just takes good parts to do it. I make 1040HP at 7000 rpm,& 900 ft. lbs. torque @6000.I'm 600 inches@13to1 compression ,n/a,kinsler fuel injection,on race gas. Pump gas at 11 to 1 with a big cam is borderline but might work.I would not walk away from an engine just because it has an alum block.Just do your due diligence,who built it,who maintained it,who had it apart and why.A leak down test will tell you a multitude of sins,if you can get some oil,do an analysis,that also tells you a lot.Even the guys at Sterling who are the best ,will tell you that if you run one of their engines wide open all the time there're only good for 50 hrs. before refresh,run um easy there're good for 250 hrs.

tomcei

Thanks guys,
I will see if I can get a parts list or some kind of build sheet. I dont think it's asking too much for a leak down and dyno run. If it's not very practial to use someone elses dyno, What do you recomend I do to insure a fair pull and an accurate reading.
I know about the air temp base line but what else or is it just to dificult to monitor?
PS: myskater32, that sounds like a nasty son of a gun

Donzi502

We are toying with Aluminum heads on our race boat this year and our engine guy who is very good is going up 1 compression point from the current cast Merlins. This is the same set up as his own engine that makes 1100 HP on 100 octane max and 1054 HP at 6000 operating RPM. His engine runs reliable. Interesting thing is that he likes to keep the combustion chamber as small as possible to concentrate the heat into the aluminum so it gets dissipated quicker. Hence, the extra compression. The thing is that if we change pistons and leave the chamber the same size. Say 118 then we can only have .75 more compression at most. The other interesting thing is that the more compression we have, the more RPM he is happy for us to run, although I must say a sustained 6200 rpm is playing mary hell with the valve train. We have 8 races and it’s looking like lifters, push rods and rockers at half way point to be reliable. Lastly we have three tubes welded to the block each side and bolts tapped into the bottom of the heads to help hold them on and that with all cast iron. We have done some research on Aluminum blocks and the general consensus is that for race marine use at least, we would all much rather have some kind of sexual disease as it would be easier to get rid, more fun in the initial stages and about the same amount of hassle during ownership. The cost of remedies and downtime would be much less with the sexual Disease as well. Just my thoughts but we have spent some fair amount of time making them. Jas

Donzi502

Last thing is our engine guy is expecting a solid 100 HP increase with Ali heads and that with a starting point of 875 give or take 10. I think stay with cast iron block and spend the money with Jessel, whipple and a cool 4 blade to give extra lift to match the extra weight. Jas

MYSKATER32

I'm curious ,what are you putting this in and what did it come out of ?Hopefully not a bravo drive !You'll spend more time working on the drive than the engine,i speak from personal experience ,i learned the hard way! On alum heads,if they are the exact copies of cast iron heads ,the cast will make more HP.The cast iron keeps more heat in the combustion chamber,thus more energy.The obvious advantage of alum is the weight,and a lot of options on runner sizes and valve sizes. Here again i would not pay extra just to get an alum block,but if the total package is a good price and an alum block happens to be included great !