Hey all, I don't post over here much (although I'm sure some other Dakota R/T guys will recognize my name) but I think this is probably one of the better places to ask a few engine related questions due to the abundance of turbocharged small blocks. First off, here's my current setup (I've already ruined one stock bottom end):

-58mm throttle body
-4bbl m1 intake port matched
-mopar 2.02 r/t heads flow 260-270cfm from .500-.600
-harland sharp rocker arms, smith bros pushrods, hughes 1110 springs, custom bullet cam 226/226 .544/.544 112*lsa

Essentially I have a pretty stout top end and my tune is rock solid (11.7 afr across the board) but on pump gas (92 octane) with 26* timing at 10psi I think my pistons/rings didn't want to cooperate any longer. My intake temps are about 140* without an intercooler although I will have a meth kit within a couple of weeks and now my timing is at 20* which should be plenty safe especially once I'm spraying meth (I hope). I'll find out next week what went wrong with my pistons but it for sure didn't hold compression. There aren't any holes in the pistons but I think the rings and ring lands let go.

I'm wondering how many of you guys have used Probe pistons and if you had any luck with them? Without wanting to spend 1000 dollars on a set of custom JE's I think the Probes are probably my best bet unless there are any other off the shelf forged pistons that might be worthwhile (if so please let me know what you'd recommend as I'm open to suggestions). Unfortunately the Probe's are only available in 4.030+ so I'll have to get the cylinders bored which is going to add to my total costs.

What rings would you suggest for this? The most boost I'll probably ever see is about 15psi, IF I even go that high with it (which would only be at the track for a pass or two). Most likely 10-12 tops though. I'm using felpro head gaskets so I don't want to push the limits of those either (I have head studs holding the heads down though).

Will the Probe pistons (or others if there are other decent options available) work with stock reconditioned rods? I feel like a set of recon rods with ARP bolts should hold up just fine for what I want to do. I don't want to go crazy with boost or power, maybe about 500whp or so give or take some. I can't go that high with my current fuel system but if I had a stouter engine I may consider upgrading my fuel system. I don't think my combo with 12psi would break 500whp though, definitely not more than about 550whp (which would make me very happy to see).

I'll probably use the stock crank and main caps, although I'd be using main studs. If for some reason you would advise against this let me know. Billet caps just seem like a lot of money and for as often as I'll actually crank up the boost I don't think I'll need that much security. (this is a street driven vehicle that might see a few dozen passes at a track each year). I have a 6psi spring in the wastegate at all times and a dual stage controller that will get me up to a max of 12psi that will mostly be used at the track or on the dyno, or if I come across something interesting on the street that wants to race which doesn't happen often. I'm not much of a street racer I just like to have a good time while I'm driving and 6psi definitely does it for me. I like to make it home in one piece so there's really no need to drive around at 10+ psi all the time.

Aside from that I'll invest in a better oil pump and pan. K1 has a crank with a 3.79" stroke that sounds pretty interesting but I feel like the money needed to make that setup work would be out of my price range anyway. Otherwise I don't want a stroker crank, I'd like to keep it a 360.

Essentially I'd like to keep the costs down as much as possible but I need something that is going to last longer than a stock bottom end which seems to be my weak point right now. I feel like anyone that boosts a stock bottom end is on borrowed time, period. I've never known a stock bottom end to last very long once it experiences boost. After going through one I know this second one is only going to last so long so I'm wanting to rebuild my old one as quickly as possible but I'd like for it to actually last a while once it is together. I think the pistons/rings are really the weakest links and for the turbo I'd like to upgrade the oil pan/pump while I'm at it. So without spending 5 grand on an all out forged beast what are your opinions on this idea? Am I wasting my time trying to save money or can I get by with a budget build that only needs to handle 6psi/425whp every day and occasionally visiting the track for some 10+ psi 500ish whp passes while staying in one piece and allowing me to make it home afterward? Thanks for your input.

sounds like a cool build. while i dont have any first hand experience with turbos, i did sell a magnum 318 to member of forabodiesonly.com

he has a k-car that runs 10's (check on u tube!) on the turbo 4cyl and said he wanted to build a turbo magnum 318.

anyways, i will try to dig up his contact info, but you might want to try posting there in the tech section to get a hold of him.

I'm not an expert, but as a "rule of thumb" stock cast pistons are limited to around 5 lbs boost if the tune is perfect. If you were up around 7-10 that's too much. Also, 11.7 AFR is pretty rich... but may not be rich enough under full boost. The meth injection will help there. Hopefully you can also tune to get higher AFR under low load/cruising to improve efficiency and reduce engine wear.

For 7-10 lb, I'd suggest a shelf stock forged piston minimum in the compression ratio of your choice with ring gaps set for boost (wider).

If you can post some pics of your failed pistons, that will help diagnose the problem.

I haven't taken the old engine apart yet but I plan on it probably sometime next week. Installing my new engine is more of a priority at this point in time. The pistons don't have any holes in them so I'm assuming it is a problem with the rings or ring lands. My compression test probably 2 months ago showed cylinder #1 only holding about 60% of what the others were holding. I've been driving it daily since then and matters have gotten progressively worse.

I do know the rings are very close to the top of the piston and although there are other Dakota guys seeing 10+ pounds of boost on the stock pistons I like to think they are on borrowed time. Not only that, most boosted Dakotas have centrifugal blowers and unlike a turbo they only see max boost at max rpm. I reach max boost shortly after I nail the gas pedal and as low as 2500rpm and it stays there until I let off. Correct me if I'm wrong, but that's putting relatively more stress on the pistons during any given WOT opportunity.

It's all in the tune... And fuel quality and IAT.

Btw - I'm running the off-the-shelf Probe pistons in mine now. The stock pistons and rotating assembly never failed, but I knew that after putting 16 psi with some occasional spikes to 18 psi or more for the past few years - that it was on borrowed time. I didn't care about the pistons, but knew that I didn't want to go looking for another block if I pushed to ultimate failure.

As was said, it's all in the tune.

I ran 12-14 psi for a long time, on a 2.2 T1 setup. One day the turbo started blowing oil smoke so I put in my "spare" bigger turbo. Forgot to hook up the wastegate vacuum hose and on the test drive I rattled the engine for about 2 seconds (20+ psi boost is what I saw when I glanced at the boost gauge). Immediately got off it, pull off the road and shut it down. Hooked up the hose and went home. Next day going into work (75 mile drive) I started hearing a funny noise, rod knock.

The big end of the rod was out of shape and the rod bearing was hammered. Pistons were fine. So it doesn't matter how fancy the pistons are if it rattles at high boost you will damage something.

I had an intercooler that I was going to put in before I dialed up the boost, but alas, I hadn't done it yet and paid the price.

Didn't you ruin some pistons not long ago though? What rings are you using?

Good to know you're using the Probes. I think that's probably what I'll end up with, however it says on the website with a 60cc combustion chamber I'm looking at 9.8:1 compression, although on another website it suggests 9.5:1. That's a bit high but I'd consider just using a 3.5 pound spring in my wastegate instead of the 6 pounder just to be safe. The dual stage boost controller will take me up to 7. I haven't had my heads CC'd but I think they're supposed to be at 60ish from Mopar and they haven't been molested yet.

I switched wastegate springs at the track and pinched the diaphram when reassembling it. It went like a scalded cat until it ran out of fuel system at about 1,000' or so. The telltale said it made 18 psi somewhere along the way. It blew a hole about the size of a quarter in the top of #5 piston and actually melted the center of #3 as well. That was not the piston's fault, and I wouldn't have expected any piston to hold up to that abuse. (lean) I only replaced 3 of the pistons. The rest looked fine. I just had them balanced to the rest of the pistons' weights and back together again.

With my block decked - the pistons are .006" out of the hole, so I am running a .051" thick Cometic to get the quench down to .045". These EQ heads are supposed to be 62CCs but I measured 66CCs after I reshaped them some. I guess I'm running at 9.2:1 after running the numbers.

I'm running Total Seal Conventional Classic Steel Top piston rings. CS3690-35 Stainless Steel top ring, with cast iron second. Both 1/16" with a standard 3/16 oil ring.

Refresh me on what size converter, gearing and tire? Also, what kind of power did you make? Track times?

I am almost ready to go to the track with mine!

I haven't been to the track yet and won't have it on the dyno for another week or so...hopefully on the 7th or 10th of January. I need to get my new engine in the truck and running and get all of the bugs worked out, then slap it on the dyno to see how it does. Currently the engine is complete and ready to drop in, I have a few hours of work left to do over the course of the next few days when I'm free...

Truck weight empty, without me is 3800 pounds. 3200 stall converter. 28" tires. 3.92 rear gears. No track times or dyno numbers yet, although the previous setup made just over 400whp at about 6psi and the only real change I've made (aside from the new bottom end holding compression) is the camshaft which I guess won't help me a whole lot, but I'm excited to see what my new numbers will be at 10psi.

I will be interested to see how 28" tires with 3.92 rear gears works. I have 30" tires with 3.54.

I sure hope it works. Being a daily driver it works out great (actually my street tires are 27" but they are pretty much worthless at this point). For drag racing I'm not really concerned with getting the best 60's in the world but I'm definitely interested in seeing what kind of times it will run. Straight to the track and home on the drag radials. Sway bars, spare tire, tonneau cover and all...probably weighs 4100 pounds like that without much gas in the tank.

Awesome! Keep us informed!

I may have too much converter (4500 that flased to 5000 on the dyno). I weigh about 3500 with me in it. The first time, I won't drive it to the track, but after that, it's on!