hmm...replacing pistons without pulling motor eh?...sounds intriguing...maybe I can find a writeup or something that elaborates on this...

Thanks for the help, I think I've learned my lesson 'bout mailorder tuning...trips via trailor, or backroads to the dyno will be the only route from now on...

 

I've done it enough times. . .

Works like this:

You drain the coolant and the oil, remove air intake, headers, TB, intake manifold, valve covers, rockers, pushrods, and cylinder heads. On the driver's side head, you have to pull the alternator and 2 accessory bracket bolts. This leaves the short block, radiator, fans, accessories, and transmission all bolted up and still in place. You support the engine with a hoist attached to the front driver's side of the block. Remove the driver's side motor mount bolt. Lift the engine as high as it will go with the passenger's side motor mount still hooked up. Remove the oil level sensor, then the oil pan. If it doesn't slip out, then try turning the crank - sometimes the front counterweight gets in the way. At that point, you can get to any of the rod bolts and knock the piston out.

Keep in mind that you have to closely inspect the bore. Since you aren't boring or honing it, the cylinder has to be pretty straight for the rings to seal.

Mike

 

lol all that work, might as well pull the freaking engine, u aren't saving any time by doing it your way

 

Well. . . let's see here. . . you don't have to pull the fans, radiator support, radiator, balancer, accessory bracket, Opti, transmission, converter, etc. . .

I've replaced a piston in a 12 hour day before, start to finish. I highly doubt you could pull the motor, replace the piston, and put it back in a day.

 

the things you listed would take about an hour to remove max.
I would say it would take probably even less time to pull the motor and do it right, then doing it your way. You can have the whole engine out from the bottom in less then 2 hours.
Marcin

 

If your 02's read anything like mine, high 800's is around a 14.0 a/f. I was reading ~915 and my a/f was 13.5, then I got dyno tuned and my A/F is 13.0 across teh board and my scanmaster reads ~935-940. So my guess is your running lean as hell.

 

I've pulled the engine from the bottom. I've pulled engine from the top twice. I've replaced pistons with the engine in the car three times. It is MUCH quicker to leave the engine in. You're not talking to a novice or a beginner here. If you take 2 hours to pull it from the bottom (probably more like 3 or 4), you still have to remove the accessory bracket and tranmission, then unbolt if from the crossmember. Then you have to take off the intake, heads, and oil pan. By the time you have the engine out, I coulda' had the headers, intake, and heads off. Once the headers, intake, and heads are off (they gotta' come off anyway), the only thing left is 1 motor mount bolt and the oil pan. In fact, everything that I do when swapping a piston in situ, you have to do also, plus deal with alot of other stuff I don't touch!

BTW: It takes longer than an hour to remove the fans, radiator, balancer, opti, and transmission.

 

I feel for your pain. Broke 3 pistons with a procharger at 9psi with way too much timing added in. The motor gushed the whole underside of the car with oil. At that point, I learned my lesson.

We'll, ever since I rebuilt the engine 6 years ago, it has run really good. I did have a problem with the top end of the motor earlier this year and that has been fixed. Now it revs like no tomorrow with a new valvetrain and better cam.

Obviously you need to install forged pistons. The problem is your bore is not going to be big enough without honing it. Forged pistons need a larger piston-to-bore clearance, such as .005". Your existing piston-to-bore is more like .002". So, IMO, replacing the pistons with the motor intact is not an option.
And, if you are going to replace the pistons, you may as well get good connecting rods too while your at it. Or, you could order a built forged short block w/4 bolt mains for around 3 grand (import parts) or 4 grand (US parts).

You will not make as much power going N/A, but it will be more reliable. Maybe build a 383 nitrous motor. Sometimes, wish I did that.

 

I agree, If you got into the 800's on your O2 sensor millivolts then you went way too lean for a supercharger at wide open throttle. My dynojet wideband O2 shows 12.0 AFR while the stock O2's are at .960.

 

In regards to swapping in pistons with the motor in the car, I'm sure he's referring to me only replacing the damaged pistons with OEM replacements. Not replacing all the piston's w/forged. Even if you could get pistons w/proper size good luck getting them the same weight.

In regards to the O2's...It was mostly in the 900's, but I've been warned by many people that OEM 02 sensors cannot be trusted for detailed analysis. Especially since i've never compared mine to a wideband to see how accurate they are. Also, it's my understanding they vary ever greater as they're temp changes, which is why you should only use them for EXTREME lean or rich conditions. I may be wrong, this is just how i've interpreted the info presented to me. As far as replacing the piston...I may do it with the motor in the car.

I'll do a leak down test, try to pin point what cylinder(s) are damaged. I have 6 spare stock rods and pistons in my garage. So i guess as long as the bore checked out I'd be in business with little outta pocket expense. I have all lifts, etc, etc...afterall this car was a bare chassis 3 weeks ago.

Yeah, my plan originally was having this motor last 6-12months while I built up the last shortblock I destroyed, into a N/A stroker. I've been tempted to sell the s/c and get a nice set of heads for a while...get a cleaner more reliable setup going...time will tell, if I can get my current setup back on the road for cheap, I'll try that route first.

Thanks again for all the input...

 

i was gonna say just what engineermike said.. stock pistons are CHEEP and if the rest of your shortblock is as healthy as you stay it is you can just find out which one is bad and replace it and get this tune deal worked out and drop the boost a pound or 2 and you should be ready too go...im currently in the same boat as you BUT my engine has 200k on it and was in TERRIBLE shape.. i cant even describe it.. i had them intake off and it looked like someone rand 50k miles inbetween changes i scraped a half of one of the big coffie cans of gunk out of it because it was get it out or get the motor out and rebuild BUT it still ran great somehow but anyways too make a long story a litle shorter this was my first FI experience and i was just kinda learning and adding parts as i went but i was running a 9lb pulley on a Bd-11A powerdyne that would make 9lb easy with no belt slip so i kept it where it would only make about 5-7lb on the street before slipping (just hadnt came across a 6lb pulley yet and liked how the boost came on very early) but anyways i drove it probably close too 10k mile flogging the **** out of it every mile of the way an i had a BONE stock engine stock injectors,manifolds,tune, all i had was the PD FMU, autolite 104s MSD inline pump and 255lph intank. So that just goes too show you definatly have a problem.. i say fix the piston wont cost crap get the tune figured out and i would think you should run an FMU eather way you can always adjust it just seem like good insurance too me..

 

BTW i was also driving that car 100mi a day back and fourth too work every day and rapeing the **** out of it on race gas at the track every weekend never got dynoed but id say i was getting a solid 375hp too the wheels i trapped 108 spinning BAD 1st,2nd,3rd and then the clutch totally letting go in fourth.. i think it had an easy 110-112MPH and atleast a 12.70 in it and it held togather very well considering

 

The clearance is built into the piston. With any quality set of pistons, the cylinder should be dead on the spec size, i.e. 4.000, 4.030, 4.060, and the piston is .002 - .005 smaller. There are some rare cases with crappy Badger pistons where you have to bore the block to match the piston, but it's only because the cheapo piston machining operations have loose tolerances.

Mike

 

Why don't you just buy a beater to drive and park the car while you get your NA engine setup? No offense to anyone but I wouldn't waste my time replacing one piston on an engine that will only see use for another 8 months.

 

I totally disagree. But I have pulled at least 25 of these engines before. With experience, taking the engine out to me is easier than what you described. Especially if you have headers on your car.