bobl

A while back I posted a thread about some modifications to a 6.2 for one of my customers. Finally got it all finished and wanted to share the results. A brief recap of what I did. The boat is a 2002 Cobalt 206, 6.2 with Bravo 1 drive. I ported the Vortec heads, added 2.02/1.60 SS valves. Went to a slightly larger cam, added Stainless Marine exhaust and switched to a custom MPI system with a 4bbl type throttle body and FAST ECU. That EFI is a really sweet deal. I spent about an hour on the water tweaking the base map and was good to go. Anyway, the results.....before the mods we got a best speed of 58 on GPS at 4800 RPM. After the mods on the same lake, same prop and about 20 degrees warmer temperature. 65 GPS at 5400 RPM. I didn't dyno the engine, but it certainly appears to have picked up close to 100 HP to gain 7 MPH. It seems to have a little more torque than stock all the way across the board, but when it gets to about 4800 RPM(where it quit stock), it really comes alive. I wasn't real sure how that engine would respond to the mods, but I'm very pleased with the results. It is still very mild. It has no detectable lope from the cam and starts easier and runs cleaner than it did stock.

Tinkerer

Thats the whole trick. Build more HP and run good with no more maintenance than stock. I love to take a stock engine and make it beter.

Ric232

Bob,

What was the total cost to the customer?

Also, was the new new fuel injection system a throttle body system, or is it a true port injection system?

bobl

Ric, this is a true MPI system. The intake looks like a Dart with a 4bbl type throttle body on it and fuel rails(similar to the Holley Commander 950 system). Total cost ended up being around $9k to the customer. The EFI system with FAST ECU and 02 sensor was almost 1/2 that cost.

Bob

dyno

9k holy cow!

rmbuilder

Bob,
I am building a 383 with Dart Sportsman II heads and considering using the CompCams XM 270 HR roller for this application but was concerned about the idle and docking manners for this cam. I think this is what you specified you were using in your previous post and just wanted to verify the grind and idle quality.
Thanks,
Bob

bobl

That cam is very mild. No lope to it at all in my application. However, keep in mind I was tuning the idle with a laptop. I did mess around with the idle map some and at one point it had a pretty good lope from the fuel mixture. But, properly set up it idles very smoothly.