phughes69

I am going to start a build thread on converting my Mercruiser 476 HP Gale Banks twin turbo engines to EFI. In doing this I have set out some limitations and goals.
1. Reuse as much of my existing equipment and parts as possible.
2. Reliability is the #1 top priority,
3. Driveability is a close 2nd.
4. Budget is a concern.
5. What items will I have to compromise on.

My existing engine consists of the following
1980 454 block 4 bolt main
GM forged steel crank
7/16 GM forged rods
TRW forged blower pistons with pressed pins. 7.5:1 compression ratio
Iron rectangular port factory heads with stainless 2.19 intake and Inconel 1.88 exhaust valves
Crane gold rockers
ARP rocker arm studs
ARP head bolts
Felpro Marine head gaskets
double roller timing chain set
Nothing too fancy in the long block.

Here is where it get interesting.
Intake system
existing: dual plane Mercruiser intake manifold
PFM dual core intercooler that sits on top of the intake manifold
Draw thru Twin Rayjay E trim turbos with the bypass hole in the exhaust housing welded shut.
single 800 CFM Holley double pumper with electric choke
mechanical 110 gph free flow fuel pump preset at 7psi
mechanical waste gates calibrated to open at 10 psi of boost

Ignition system:
MSD distributor, rotor locked and timing set at 32 degrees of timing.
MSD 6 ignition box
MSD rev limiter.
7 mm wires.

Exhaust system:
Mercruiser rear exit iron log manifolds
1" thick plates for the wastegates between the manifold and the turbo riser.
3/8 studs to attach the turbos to the manifolds.

Wishlist for the new EFI sysytem:
1. sequential fuel injectors
2. individual cylinder control for spark
3. coil on plug ignition
4. adjustable boost control.
5. methanol injection
6. O2 correction
7. knock detection
8. Multi octane spark/ fuel table selection


I already have some parts purchased but will continue to post pictures of the old system and the new system. I also have to give big thanks to Mr. Gadgets who has guided me with some of my parts selection so far and Akattack for detailing the original history of the boat and how he modified the original turbo system.

14 apache

iTrader: (1)

If your looking for individual coils ls style let me know. Multi tune I think you only need one tune and just up the boost when you have good fuel in the boat. What ever ecu you go with make sure it has a good auto tune look at the holley self tune on YouTube will pay for itself on the dyno. And use hall effect pick ups is a must. Think a center riser manifold would be a good upgrade. Great efi fuel pump is a Weldon that's what mercury uses. Would find a good mpi intake open plenum.

Gimme Fuel

I used good ole GM LS3 ignition coils on my 548 mounted on individual brackets that mounted to a exhaust manifold bolt on each cylinder. I used batch fire ignition as sequential in a marine engine doesn't gain anything over batch. Made install much easier otherwise I would need to use a distributor for cam sensor. My Holley HP system runs off of the crank sensor only. Just an Mallory oil pump drive/hole plug is in the distributor hole. I also used a single knock sensor but the Holley HP has provisions to run dual sensors. Holley HP can also run dual oxygen sensors which I would recommend for boosted app. I just used a single on my NA app.

phughes69

The original 475 HP system was a 370 hp long block with low compression pistons. It used log exhaust manifolds, Rayjay turbos and was not intercooled. The exhaust housings had hole drilled in them anywhere from 3/8 to 1/2 to bypass the exhaust gas to limit the boost to about 6 psi. The carb adapter had priority valves in it that would allow the intake charge coming from the carb to go directly into the intake manifold and bypass the turbos. Once the turbos began to spool up the boost pressure would force these valves shut and all the intake charge would then go thru the turbos and into the intake manifold. I am guessing that Mercruiser did this to improve the low speed idle characteristics of the engine. from what I am guessing and have read, Reggie wanted a hot new power plant for his boats back then. The turbo systems were very temperamental back then and I have seen several boats that use to be turbo engines and the owners yanked them off. In a heavy offshore boat, these systems probably had a lot of turbo lag, especially with the low compression ratio. I have seen a lot of the Gale Banks systems used out west on the small lake boats and the owners are making at minimum 600 hp up to 1000+ hp.
[ATTACH=CONFIG]548535[/ATTACH][ATTACH=CONFIG]548536[/ATTACH]

My system limitations:
My system uses a PFM dual core intercooler and a 800 cfm holley carb. The problems I have is that the afr ratio is horrible at cruise speed and fuel distribution is atrocious.
At cruise speed (about 3000 rpm @ 45 mph @ -2 in/hg the afr is in the 12.5 range. The engine likes to idle at the same afr. I have rebuilt my carb and checked everything in it, and rejetted it for the best looking spark plugs. My biggest problem is cold starts and cold engine driveability. The path the intake charge travels from carb to intake valve is about 4-5 feet. With the intake path being that long, if I went with a bigger carb to make more power I would lose a lot of low speed driveabilty. And when the engine and intake system is cold I get a lot of fuel puddling in the intake tubes between the turbos and the intercooler.

[ATTACH=CONFIG]548532[/ATTACH][ATTACH=CONFIG]548533[/ATTACH][ATTACH=CONFIG]548534[/ATTACH]

phughes69

Currently my intake system consists of a factory aluminum dual plane manifold with the PFM dual core intercooler on it. The carb is the original 800 cfm holley. The carb sits on a heated plenum that then feed the inlets of both turbos.
[ATTACH=CONFIG]548537[/ATTACH][ATTACH=CONFIG]548538[/ATTACH][ATTACH=CONFIG]548539[/ATTACH][ATTACH=CONFIG]548540[/ATTACH][ATTACH=CONFIG]548541[/ATTACH]

The new system will be a stock LS1 throttle body bolted directly to the inlet of each turbo. The throttle bodies will be connected by linkage, and the throttle cable will be connected to this linkage
The new intake manifold is a Professional Products single plane intake modified for fuel injectors. Since this intake only comes as a dominator top flange, i have to use an adapter plate to go between the Dominator (4500) flanged intake and the 4150 flanged intercooler. The new system raises the intercooler up about 3 inches, but this will give me additional clearance to route the pressure tubes from the turbos into the intercooler. I will still have about 1/2' of clearance to the hatch, but this also means I would not be able to use a 4bbl style throttle body in the original location (hence why I'm going with LS1 TB on each turbo).
[ATTACH=CONFIG]548542[/ATTACH][ATTACH=CONFIG]548543[/ATTACH][ATTACH=CONFIG]548544[/ATTACH][ATTACH=CONFIG]548545[/ATTACH]

ezstriper

I would say alex haxby the guy to talk to...the dual throttle bodies going to get interesting, not saying impossible. you say the mid range is terrible..before I went thru all this, and I have done all kinds of EFI/turbo/blower deals, I would consider trying a new quickfuel carb, I know what you are thinking..WTF ?? but if you tune it with a wideband, and get a handle on how adjustable these carbs are you will be amazed. you can tune the power valve channels, and air bleeds to dial them in...they are no way like the antique carbs you have now...just a thought...Rob

MILD THUNDER

iTrader: (3)

How much power are you looking to make ?

Those heads, cam, and compression are a big limitation.

GPM

Maybe pipe the turbo's into a dual inlet carb hat and a 4 barrel throttle body all sitting on top of the efi manifold you have pictured above.

GPM

Would a front mount intercooler be out of the question, might not fill the motor with water if it ever leaks, just a thought.

phughes69

I hear what your saying. I almost pulled the trigger on a pair of 850 cfm Quick Fuels this summer, but that was almost $1200. My estimate for the ECU's injectors, intakes, and wiring harness is $2400.00 so far. and by converting to EFI I can have knock detection, adjustable boost control and complete ignition control all in the same box. Right now I have 3 MSD boxes taking up space on my transom.