I am getting ready to pull my motor and do small freshen up. I want to get just 5-10% more power out of the 2200.

I have some 1.6 roller rockers, and a header already, have thought of the tb mod, also am sitting on some +1 valves, but may not put them in.

Thinking of pulling the head and milling 30 thousandths off of it, and doing some clean up and port matching to it.

And lastly thinking of pulling the cam and sending it to Comp to grind it to similar specs of the IPP stage 1 cam.

Madjack had the following to say about this cam:

Stage 1: "Good idle for daily use. Improved low to mid range torque. Use stock springs and retainers. Stock compression OK, but will work better with increased compression."
Duration @ 0.050": 202*Int./208*Exh.
Lobe Separation Angle: 112*
Lobe lift: 0.274"/0.284"
Lift @ valve: .438"/.454"
The idle characteristics should be close to stock with maybe a loss of 1" or 2" of vacuum. Should not pose any problems with the PCM. The torque peak occurred between 3000 and 3500 rpm, with a gain of about 12 lbs/ft. The peak horsepower occurred at 5000 rpm and it gained about 5 hp. The peak may actually be 100 to 200 rpm lower. This would be a good RV cam or towing cam, while gains are made, but at lower rpms than stock and are milder than the other profiles. Increased compression helps, but isn't needed.

I may ask comp about a cam between this and the stage 2, but really want something mild to try and retain some decent fuel mileage.

Anyone have any thoughts on what that proposed build would due in the fuel economy arena? I would also be running a stock tune for now.

Thanks!!

I wouldnt waste time on a cam with the stock tune, you really wont see much of a gain. And if you really want to increase fuel mileage a tune is where you're going to find where those 2-4 mpg are hiding.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

I should not have mentioned the tune, in other threads where I talked about it I got some negative feedback.

This is a natural gas car, when you look at it with hptuners the files are not ones that can be modified. So no tune is possible.

I have built alot of motors though, and run them on the dyno while tuning etc. There is power to be made with a cam swap, I have run stock tunes before with a very mild cam and seen improvements just fine.

Oh, you're the gas car guy. Are we talking you ran other recently made chevy 4 cylinders with cams on the dyno or something else? GM 4 bangers are odd beasts, there's not much to be gained from doing bolt ons and cams but theres huge amounts to be gained from tuning, the opposite of hondas which make huge gains on boltons and tunes dont do too much.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

Unfortunately yes, I am "that guy"

If I spend the time to open that head up a little bit, it just makes sense to get just a little more lift and duration from the cam to benefit the flow changes.

I have the 1.6 rollers, if I am truly wasting my time sending the cam to comp I will leave it in the block. But for the $88 they told me to grind it, seems like I should have it done?

I have never puttered with this engine before performance wise, I probably should just leave well enough alone. But for around $300 I have my rollers, a ceramic pacesetter, can port the head and have it milled and have the cam ground. I would have to see 5-10 hp doing that list.

I just want to make sure I won't lose 5 mpg doing this. If so I will leave it alone.

Thanks

It stinks your not able to tune the engine, but i do agree with the others. Our ecu's are alpha-n which means throttle position vs rpm so more air wont mean more fuel because the engine wont read that there is more air. You may feel a little difference, especially since the cam specs are so close to stock, but it will be piddly compared to if you could tune the car. Essentially you will just be leaning the afr.

That makes me nervous, thanks for the explanation. I had no idea it would not use afr readings from the O2 sensor and richen the mixture.

I doubt anyone knows how the cng system reacts, it is likely since it is a factory system that it uses the same setup as the regular fuel system and I would not get any enrichment.

With this in mind, should I even do anything to it?

Or should I just put it together stock and leave it alone?

Well if those are close to stock spec cams I doubt anything will be hurt even with a P&P on the head. Reason being is from the factory our cars run pig rich anyways. If you were going with a more aggressive cam then I would worry about a lean condition. In the 2.4 world before HPtuners people were running the slightly larger "secret cams" with P&P heads with no ill effects. Just never made much more power than stock until they could tune years later.

As for the o2, they do monitor afr to a point. While in closed loop, which is basically idle before the car warms up or cruising speed, the ecu will command an afr of 14.7 for good fuel mileage. Once you start accelerating it kicks into open loop where it gets it's afr commanded by the tunable charts in the ecu. They are set to a specific afr based on the amount of air the engine takes in in stock form. For example at 4500 rpm and 75% throttle the ecu reads the table and adds the amount of fuel allotted in the table for those values to meet the predetermined afr.

Hope that helped.

Theoretically what the car learns in the long term fuel trims gets applied to the open loop fueling. Which is why stock cars and cars with more tuning options dont have a major change in tune going between gas stations and winter/summer gas.


1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by: Kronos Performance

WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer

So the ecm could learn a little while in closed loop to apply towards open loop?

I guess the million dollar question is will I see a power increase with these small mods and will it not run too lean?