bobl

I'm in the process of modifying a 6.2 Merc Smartcraft engine for a customer. I thought I'd share some of what I've learned so far. It has a standard 2 bolt 5.7L block, GM powdered metal rods and an internally balanced forged crank. Not knowing what cam was in it, I measured it before disassembly. It is a hydraulic roller with the exact same specs as the Crane 104224 cam. 214/220 duration @ .050, .452/.465 lift. I have used this cam a lot in 5.7 and it works really well. I'll be stepping up to a little bigger cam for this engine. It has the Motorola ECU and uses a Hall Effect crank trigger. The distributor housing is made of plastic and it uses a rally trick flat distributor cap. I'm replacing the Merc EFI with an aftermarket system and FAST ECU. This, along with larger valves, some port work and headers should wake this engine up quite a bit. I'll post the results when finished.

Bob

Dennis Moore

I was at Mercruiser school when the engine was new and they gave me a new products info book (printed in January 2001). I didn't have the camshaft specs, so thanks for posting them.
I will list the important things that are in the book;

4340 forged steel crankshaft, Kellogg forging machined by Lunati.
Special main and rod bearings are required because of the larger fillet on the main and rod journals.
Single groove crank key and single key.
The powder forged connecting rod is machined for camshaft clearance.
A special chamfered connecting rod nut is used for block clearance. Nut torque is 36 foot pounds.
Compression ratio is 9.0:1.
Sincerely
Dennis Moore

Whitey

Be sure to post results, thanks Dwight

Whitey

What are you replacing the merc stuff with? Thanks

bobl

I will be using a single plane 4 bbl. type intake with a 1200 CFM throttle body. Similar to the Holley commander 950 system. I'll use the existing Merc fuel pump system, 40 lb injectors and the Speed Pro - FAST ECU and wide band 02 sensor. The merc intake system is designed for low end torque and doesn't flow but about 600 CFM, so it can't support any real HP increases.

cobra marty

What will this cost and expected output verses putting on a Whipple?

bobl

Interesting question Marty. We had originally ordered a Whipple. But midway through the process found out that they had not sorted out the program for the Motorola ECU and it would be some time before it was available. So we cancelled the order and went to plan "B". I anticipate about 450 HP from this setup, opposed to 500+ with the Whipple. Cost is going to be similar. Seems to me the Whipple would be a better choice. However, it wasn't available at this time, and the customer decided he wanted to stay naturally aspirated...so here we go.

Whitey

How will you utilize the O2 sensor with the water cooled exhaust? Is the mercruiser ignition set up adapted to the new processor? Sorry for all the ?s but I have been waiting for someone to take on a project like this. Thanks Dwight

bobl

There is a risk of water on the 02 sensor. You need to mount it in the top of the riser. There are several folks that have been running them successfully for quite a while now. The main use is for initial tuning. Once you get the base map just right the 02 sensor will be doing very little correction, so you could really do away with it. The intake is a Vortec intake. Holley also makes a Vortec EFI intake. The ECU is being set up specifically for the hall effect crank trigger and coil used on the 6.2.

Whitey

Thanks for the info. By any chance are you going to run an oil cooler?. I was told that it is a very good idea to install one on this engine. I was wondering if the O2 is even needed with the map and coolant temp sensors. Is the fuel delivery going to be a throllte body injection or are you staying with port injection? Thanks again Dwight