4A084 performance

**David** · 06-13-2010, 06:30 PM

**chuckitt** · 06-13-2010, 06:40 PM

Hey David, did you get that max hp before are after you tuned it?

Maybe that thing needs a VVT Cam Kit.

Chuck

**brlcla** · 06-13-2010, 07:05 PM

It would be so nice to figure out how to use all 84ci of the motor.... I just find it odd that it only makes 35-40HP....

**David** · 06-13-2010, 07:21 PM

This engine could be alot better for performance and it has a little more left on the table for it but with a new cam design and valve an lifters an a little head work you would wake this thing up

**brlcla** · 06-13-2010, 07:39 PM

David,

Are yall having anyone look it over? Any local mechanics willing to take a stab at it? Or are yall trying to work it at Airboat Pros?

**David** · 06-13-2010, 07:45 PM

You have a P.M Br

**djmsgstride** · 12-27-2010, 08:09 PM

If the 4A084 engine conversion incoorporates the stock magnito ingnition system and the objective remains to optimize the power and torque curves within the stated 3000 - 3250 rpm zone, just install the cam that is designed for these parameters. To incorporate all the needed machining and testing the VVT requires and the software configuration needed for the PCM is not worth the money or the effort. A more appropriate area to consider is to increase the compression ratio on this engine. The stock engine comes with the 6.20:1 ratio. Each of the cylinders need to be decked to acheive at least a 8.5:1 (for regular gas) or even better, 8.94:1 in order to reach a decent 50 horse power rating. There are just two drawbacks, however 1) the higher compression ratio requires 92 or better octane fuel, and 2) the CHT will be higher than that of the stock engine, provision for this factor is extremely important in order to insure decent engine life. You'll want to keep the heads between 500F to 700F degree range when engine is in operation. TBO on this engine should remain at about 20,000 hours.

Originally Posted by David

**chuckitt** · 12-28-2010, 06:03 PM

Yea , David was just funning when he said add a VVT Cam kit but one of our customers has had a cam profiled adding more duration and a little more lift. He also has had more pistons made. This will be for his son's boat. If his performs good, he said he would get more parts made. We are waiting for him to run it.
Thanks, Chuck

**Duane Scarborough** · 12-28-2010, 06:10 PM

Originally Posted by djmsgstride

...TBO on this engine should remain at about 20,000 hours.

Huh? 20,000 hours?

I'd sure like to know how you came up with a number like that...

It sounds wrong to me.

Duane

**djmsgstride** · 12-29-2010, 04:48 PM

You're right Duane. The TBO would probably be in the range of between 1500 and 2000 hours. Thanks for the insight.

... and thanks Chuck. I too would be interested in how a dyno test turns out. I figure your customer is also similarly interested ... keep me posted. Also, could you tell me what the size of the main thrust bearing is? Does anyone know if Nikasil Cylinders can be made for this engine? (the cooling properties of this material would handle the higher compression)