AFR 385 on 705 ci?

[RAMM]

I guess I should have tried a more appropriate title.

I have an interesting question for you guys.

I have a pair of 705 cube SuperMerlin boat engines with Dart BigChief heads and tunnel rams with twin 1050's that are leaking water externally and ingesting copious amounts of freshwater. Upon disassembly I discovered that the very nicely done BigChiefs are in fact heavily corroded in the water jackets. Some are so bad that the water passage and chamber wall are now one.

The customer was told that these engines produced 960HP when new (not long ago).

The question I have is this---How do you guys feel a set of AFR 385's and a Wilson ported 2927 with a single 1250 Ultra HP would work?

I'm sure the engines would be underheaded--but I feel that lowering the compression from where it is and the fact that these engines are in a heavy 40 foot Fountain--The combo may prove adequate.

I want to move him away from the tunnels and dual carbs as these engines have been headaches from the start.

I also feel that with the 4.600" bore that the AFR 385's would produce similar HP and torque.

Oh and money is a bit of a factor--not much but it is a consideration.

One other question--How do you identify a DART tall deck tunnel from a short deck tunnel? I need to know so I can reproduce the correct spacer width if this is a go.

I appreciate your responses. J.Rob

[dezza]

Rfd do some nice heads. 500 plus cfm

[cstraub]

If your looking at a max of around 6000 rpm the head will support the inches. You will need to change pistons out and get the appropriate hardware components to go with the heads.

[cboggs]

I can offer a Marine version of my RFD24 paired with the 2897 intake has made 1000+ in
marine pump gas builds, .. but if you "mild" it down a little will make very good power and
live plenty long for a cruzer or poker run boat.

Can also hard anodize if you want. However, sounds like you might have a maintenance issue
or something else going on.

Curtis

[WeingartnerRacing]

Jesse why don't you port up a set. I know you are a very capable porter.

Hope things are going good for you.


I still wish I had that EMC video.

[Keith Morganstein]

However, sounds like you might have a maintenance issue
or something else going on.
Curtis

X2,

Is a boat of this level actually raw water cooled? If so, time to switch to a heat exchanger cooling system or the customer will just dissolve another set of heads in a short time.

If it has a heat exchanger cooling system there has to be some other problems. grounding, coolant , etc...

[Aukai]

There seems to be a bit of electricity/electrolysis going through this engine that should be looked at. Heat exchangers with Zinc anodes will help a lot. If raw water, you'll need to get Zinc somewhere in the engine cooling system. I'm sure you know that the aluminum is the sacrificial metal right now, need to get the Zinc in there with the new build. If it has Zinc anodes already they need to be checked more often.

[Keith Morganstein]

Heat exchangers with Zinc anodes will help a lot. If raw water, you'll need to get Zinc somewhere in the engine cooling system.

Absolutely! (checking/installing zinc anodes)

[RAMM]

However, sounds like you might have a maintenance issue
or something else going on.
Curtis

X2,

Is a boat of this level actually raw water cooled? If so, time to switch to a heat exchanger cooling system or the customer will just dissolve another set of heads in a short time.

If it has a heat exchanger cooling system there has to be some other problems. grounding, coolant , etc...

I will definately suggest these points; however, talking to guys like these----Sometimes it is better to suggest (on paper), smile, take their money, sleep well knowing you did the best job you could. Sometimes I wonder where an engine build ends and the rest of the vehicle and its obligations takes over??!! As it stands right now this is shaping up to be a 40g job. The customer's mechanic took the corroded heads back to another shop that had refreshed and dyno'd the engines and they basically told him to pound sand--as they should have. Thanks for the suggestions guys, I will know later today if this job is a green light, although as I look out my office window and I see a 40' Fountain sitting there--that must be a good sign, right? This guy must think the re & re is included, HA HA HA!!! J.Rob

[RAMM]

Jesse why don't you port up a set. I know you are a very capable porter.

Hope things are going good for you.


I still wish I had that EMC video.

Thanks Eric but I have no interest in porting 32 intake and exhaust ports , nor do I think I can produce the output this guy expects by doing them myself.

Things are AOK---It really is a state of mind.

I will burn that disc ASAP--but my camcorder and computer have multiple organ failure, I should be able to though.

Eric, I noticed your name was lacking from the EMC dyno schedule??? I hope you are teamed up with someone else and hope to see you there. J.Rob

[Ted Gerstenslager]

Verify what you have for deck height. I had a pair of those, they were origionally built by Sterling Performance in Mich in the area of the mid 90's. Mine were 11.670. Common was 11.625 Merlin Iron blocks w/ .400 raised cam
I converted mine to drag with compression and sheetmetal intake w/ 2 1250's . But with the 2.400 intake valves it was out of steam before 7000. Just a guess but I don't think a conventional head will support any more than about 5500 with out using a 2.400 intake valve. And the dart cast t-rams for conventional heads definatley will not support the cubes.

[RAMM]

Well I was successful in getting one of the two engines in question back together and on the dyno. I discovered a cracked crank in the one engine so I am waiting on Callies to whittle up a crank for the block on the stand. Anyways, I went ahead with the AFR 385's with Inconel valves and hard anodizing options. These heads are nice I must say. I was able to CNC some custom intake spacers to make the ported 2897 intake and heads play nice. I had some pushrod clearance issues due to the super tall deck and a few other minor snags but all in all I am quite pleased with the result.

A little background on the previous combo: Dart Big Chief heads,Jesel shaft rocker, 11-1 comp, Dart T-Ram 1050 Dominators x 2, and with the original dyno sheet in hand, an observed 890 Hp @ 6000 rpm with 900 ft/lbs was produced.

I went to AFR 385 conventional heads, Edelbrock SV 632, Holley 1250 HP, Scorpion stud mounted rockers. Moving from the small chamber of the Big Chiefs to the much larger 124cc chamber of the AFR's dropped the static comp ratio from 11-1 to a boat friendly 9.2

The competing shop told the customer "It couldn't be done with a conventional head" At this point with two broken engines and very little run time, the customer was willing to trade some power for reliability and longevity. I think the end result is right on target.

On the SF-902 running Esso 91 pump gas, and blowing through some way small 2" headers 854 hp @ 5400 rpm and 898 ft/lbs @ 4700rpm.

A few pulls earlier with timing way back I observed peak torque @ 4400 rpm--right now the dyno will not load lower than 4700 rpm. I believe 920-925 ft/lbs may show up. I also have 3 more degress timing to try and more jet to throw at it. Not sure how much the small headers are holding it back but I may never know and don't really care at this point. Just thought I'd share this somewhat unique combo because I'm not sure if anyone has used this cylinder head on this many cubes before. Oh and I have to say my hat is off to AFR-the heads delivered. J.Rob

[RAMM]

A shot on the stand. J.Rob

[RAMM]

Dyno screen shot. J.Rob

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