From what I gather, the 2200's weak spot under boost, is connecting rods. People have stated that they like to snap at around 170HP, but what kind of torque numbers can the 2200 put down before they go kaboom? If boost is controlled according to RPM, and the stock rods can handle 180lb/ft, 212 horsepower should be possible at redline if the torque curve is flattened.
2002 Cavalier 2200 5spd
MadJack wrote:I know of quite a few JBOers who have been running aroud for yearsputting dow alot more than that on stock bottom ends.
If your really worried about, or your looking to push more than 10lbs of boost, look into the dished forged pistons and Eagle rods.
x2 what are your power goals?
My power goal is what I'm trying to determine.
I'm willing to bet that the 2200 can take quite a bit more than 10psi near redline. A turbo more or less stretches upward the 2200's torque curve. The stock rods can handle only so much torque and when selecting a boost level, we have to be careful that the torque peak doesn't cross a certain threshold that makes the rods snap. If we can determine the torque level (not boost level) at which the rods snap, and can maintain a flat torque curve by varying boost with RPM (possibly by watching injector pulse widths), then we can make the most out of the stock internals.
For example, if our rods can tolerate 190lb/ft of torque upto a 6200 RPM redline, and we carefully modulate boost with RPM, we'll have a motor that can pull hard ~185lb/ft from 2500-6200 RPM 224HP@ redline. If our rods can handle more than 190lb/ft, scale that number accordingly. My approach is variable boost, fixed torque.
2002 Cavalier 2200 5spd
interesting approach, what kind of boost control unit are you going to use to accurately maintian an even torque curve though??
If holding a motor at peak torque throughout the RPM range, even a slight variance in boost level could destroy your motor. I hope you are factoring in a % error on the boost controller, which most are prone to boost spikes.. but a very interesting theory indeed.
listening
Edited 1 time(s). Last edited Saturday, November 08, 2008 6:17 AM
Let's see...
A stock 2200 generates:
135lb/ft & 92HP @ 3600 RPM
120lb/ft & 115HP @ 5000 RPM
If we assume the torque curve is stretched upwards linearly by boost, ie: 10 PSI (or about 68
, then we'll end up with 226 lb/ft @ 3600 RPM and 201 lb/ft and 193HP @ 5000 RPM. If we're going for a safe and flat torque plot, let's say 215lb/ft from 2500RPM to redline, we'll have full torque available through the whole powerband rather than a bump at 3600RPM. Also, that 193HP @ 5K becomes 254HP @ 6200 RPM, all by staying a bit under the torque peak you'd be at if you were just running a steady 10PSI.
I'd need a combination of hardware and software to limit boost, most likely on the charge pipe side of things. I've got a pretty good background with programming, electronics and mechanics, so I think I can pull it off. I have a J equipped with a wideband, but it's my N/A daily driver w/ 120k on it. It's in perfect health, but I'm hesitating to go the turbo route.
2002 Cavalier 2200 5spd
I see what your trying to do and have seen this applied before. But trust me the 2200s are tough there not puny by any means. I've heard the whole the rods are toothpicks stories also but more often than not the rods don't let go the pistons or something associated with the pistons does.
I shoved 12psi of boost down my old OHVs throat daily for the summer in Texas humidity and heat(boosted at 120+miles). POeople have pushed close to 300 on the stock bottom end but thats with really good tuning. I really think your overthinking it.
I don't think you have to worry about the torque killing your rods just your transmission.
I was pushing some decent power out of mine. 9 psi on a t3/t4 60 trim, built P&Phead, valvejob, the whole works on the head.... 6-7k miles on it and it was fine. I did snap a rod. But it only snapped cause my wrist pin seized up on the piston, so the rod bent and snapped simutaneously. (Keep in mind this happened cruising down the highway at like 3-5% throttle, and it hadn't been boosted even once that day.) The tune was good, everything was fine. Freak accident
I am running the same set up + a mild cam, M98 oil pump for safety (lack of good lubrication was a possibility for my seized wrist pin) and v8 spring swapped lifters, and it pulls quite a bit harder with the cam, and have had no problems yet...
Moral of the story... the 2200 can take a beating. If you are afraid of it snapping and thinking that much into it, then get forged to be safer.
This is a very novel idea, and its kinda how the LNF PCM works - it attempts to maintain a fixed airflow (and hence torque) and varies boost to accomodate.
Your biggest hill to climb is going to be tuning and getting the appropriate hardware to vary the boost as you describe
I've decided to pull the trigger. T3 and other hardware is on the way.
I bought a wastegate with an 8lb spring. I plan to attach a solenoid to it and drive it according to RPM, so it will be effectively a different spring depending on the RPM.
Also, once I can control the wastegate via electronics, I can set it to open completely when the handbrake is up so the turbo bearings take minimal damage when I shut off the engine.
2002 Cavalier 2200 5spd
not to sound like a dick but start searching for a junkyard motor...i blew mine at 128,000 miles on 4lbs of boost. a/f was 10.5:1 so it wasnt from tuning. timing was -3 from stock and my oil pump let go. point being same thing might not happen to you but at 120k miles the chances of failure are greatly increased due to part tear and wear vs being new. good news is i found a junkyard motor with 5k for $400. they also had 50k+ motors for $250. people on this site have made almost 300 hp on a stock bottom end with decent reliability. you're right its all in the timing. something you might not know is that if you have hptuners, you can download and license a 2.4s/c factory reflash from the supercharger kit and flash it into your 2.2 computer and it will work as long as you disable theftlock(also thru hptuners). that gives you up to 15 psi and changes your computer from rpm vs tps to rpm vs map as well as update the entire flash to accomodate 2 bar boost in every engine chart.
"...and then God said let the 2.2's have potential. Thats when hell broke loose..."
