Need new pistons....Confused on different setups, HELP

[dsmfergie]

I fried a couple pistons, I think it was actually the previous owner who was running the 14b with no line on the wastegate. What an idiot! Anyhow, I found the bad pistons when I recently had my head gasket go on me. What luck I have!

So I need some new pistons (at a minimum). I have a 6bolt and I have been told by some local DSMers that you can use 2g pistons for a bump in compression but mods are needed. Also EVO 9 pistons were discussed as well. I have looked around for a couple hrs and haven't found any write ups on what mods are needed for these pistons in a 6 bolt. Basically I want the car stock kind of reliability to drive to various meets 2-3 hrs away and be able to run 11.5 eventually with supporting mods.


What is needed and what are the benefits for:
2g pistons in a 6 bolt?
EVO 9 pistons in a 6 bolt?

What do you guys think?? Any tips would be great!!

 

[92 GSR-4]

The 2g pistons are 8.5:1 compression and were a popular mod years ago. My motor is a 6-bolt with 2g pistons and have been running strong for over 9 years, currently making somewhere around 500hp (logging over 52 lb/min in ECMlink).

EVO pistons are stronger. Not sure about the CR though, maybe someone can chime in.

As far as fitting them to 1g rods, the 6-bolt rods must be clearanced on the little end where the wrist pin goes through. The rods must be slightly narrowed to fit the 2g/EVO piston. All in all its very simple.

 

[WES_393]

2g pistons will bump the compression from 7.8:1 to 8.5:1. Evo pistons are around the same (8.5:1) if I remember correctly. However, the Evo piston is a much stronger piece. Both require the small end of the rod to be bored out to accept the larger wrist pin. The pins are also pressed in so a capable shop/machinist would have to install them as well. While the rods are out, you might as well get the block inspected and freshened up. You will definitely need the cylinders honed if not more from the damaged piston. More info on the 1g rod/2g piston process can be found on VFAQ.com.

The biggest "supporting mod" you'll need is a way to tune. Specifically: turn down timing. The 1g ECU runs an aggressive tune from the factory, which can cause problems with the added bump in compression. I would highly suggest DSMLink as your tuner of choice.

 

[Rishi]

Evo Pistons Are 9.0:1 Compression Ratio.

 

[dsmfergie]

Cool, thank you everyone for the responses. I fully plan on DSMlink this winter, currently its on an SAFC-II. Not what I would want, but it's how I got the car.

I think the 2g pistons would be the way to go. I just got the FELPRO head gasket kit, now that I am going further into the engine is it worth it to run a MLS head gasket (like cometic or OEM 4 layer)? It already has ARP head studs and the head already got surfaced.

92 GSR-4, what rings are you running?

Ok, so call me computer illiterate or whatever but I could not find anyhting in FAQ or anything about fitting the 2g pistons on 1g rods/6 bolt. Does anyone have a link by chance??

 

[WES_393]

Evo Pistons Are 9.0:1 Compression Ratio.

When used in an Evo which has a dome volume of 43cc. The DSM dome volume is 47cc which lower the CR. In fact, many performance piston manufacturers use the same pistons for the 2g DSM and Evo. The main difference in CR is from the head, not the piston. Example: Manley Performance - Sport Compact - Mitsubishi - 4G63 / 4G64

OP- The SAFC is not capable of adjusting timing, only fuel. I would definitely look into alternate methods of tuning until you can get DSMLink. The 2g piston is a good option, but like I said the Evo piston is stronger. MLS is an option, but both the head and deck must be resurfaced to a very smooth finish (50 RA iirc) in order to seal properly. Now would be the perfect time to do so if you pull the block. But composite gasket and head studs will be enough for over 400hp.

Link to write-up. This is found at VFAQ.com, not the FAQ section.
http://vfaq.com/index-main.html

 

[92 GSR-4]

Fergie,


I'm using OEM Mitsubishi 2g pistons and rings. Had I rebuilt the motor after 06 or so, I'd have gone forged or EVO 9.. but my engine still serves me well today without complaint. I have 55k on the motor and its never been stock.

What is wrong with your current engine? People have gone 10's and 9's on the stock block, and I know one guy who has made over 700whp on a stock head gasket with studs. Food for thought.

And for the previous posts: I'm not aware of the wrist pins being larger on the 2g/EVO but its been 9 years. I do remember the little end of the rod needing to be narrowed.

 

[c2ypt1c]

if you do pull the block, I would consider some ARP rod bolts (requires machining of big end of rods) and a balance shaft elimination (how's your timing belt btw?). Hell, while you're at it, you should get the whole block inspected/magnafluxed, polish the crank, and replace all bearings...

 

[dsmfergie]

WES_393 - I personally hate the SAFC-II, it just came on the car when I got it. Trust me, it will be gone soon!

92 GSR-4 - The problem with the car is the previous owner. Actually the radiator plastic end cap cracked and I replaced that and started bleeding the coolant system I saw white smoke from the exhaust:-( So I set out to do the head gasket and took the head off and found my fried pistons. The previous owner had the 14b running no boost controller, so 20+ or whatever that thing can get to. Crazy considering a hallman boost controller was literally 6 inches away from the turbo....just not hooked up. And supposidly it had a larger turbo on it but he put the 14b on for dd. He was quite a dandy.....

So here is what the car came with for mods, most not properly installed:
-190lph pump
- 650cc FIC fuel injectors
-6 bolt swap (93 tsi awd)
-gm maf & translator
-SAFC-II
-3" turbo back exhaust (don't know brand)
-CX racing front mount & piping
-solid shifter bushings and roller bearings in the linkage
-16g turbo(after the 14b blew up 14hrs into me owning the car)

Thats all I can think of for now. Plans are DSMlink V3, speed density conversion, clutch other maintenance items, a/f ratio sensor & gauge(already here) and wire tuck/engine bay clean up. Pretty basic but I want it to work right. I believe in spending a little more the first time and taking my time then buying cheap stuff and getting it done fast. I have seen way to many local DSMers blow stuff up and blame it on the car instead of their empty head. I have seen others run 10's and 11's on a dd on this site and larger cities, thats why I am shooting for 11.5ish and dd it. Crazy thing is, mid 11's would darn near rule the street where I am from.

Currently I am having a tough choice between the evo9 and the 2g pistons. I haven't been able to look at prices. I know the mods needed after lots of research and talking to fellow DSMers. I'm thinking the evo9 pistons, but I have not looked at prices yet. I am doing a full rebuild this winter, if I wasn't getting married in a couple weeks this might be done in a month. But weddings aren't cheap!!! So it's turning into a winter project.

 

[dsmfergie]

So I have heard some things about some of the Graveyard websites... I found thedsmgraveyard.com website has piston and rod combos fairly cheap. I don't know if their reputation is really bad still or not. I read some feedback about them being pretty much junk, but most of that stuff was from the past like 2 or more yrs ago. Does anyone have some experience with the company?

 

[dbunch09]

I ran 2g pistons with 1g big rods in my 6 bolt.

 

[92 GSR-4]

2G pistons were great - and still are, but I would go with EVO 9 or a set of eagle/Wiseco if you have to rebuild.

The reason I would go with EVO9 pistons is because you can find them dirt cheap and they are factory "forged", still retain the OEM quality, have no drivability/luxury expense (like piston slap that you can get from a forged piston) and they are stronger than the previous 2G design.

A Wiseco/Eagle setup can be had for a pretty reasonable price as well, being that the market is saturated with this proven combo. This setup is very strong and pretty reasonably priced. I've bought forged piston/rod combos brand new in the box for less than $500, so if you have the time you can find the deal. I recommend this setup if you're okay with spending a little extra for a nearly indestructible bottom end.

 

[dsmfergie]

92 gsr-4 - thank you very much! I have seen some pretty good deals on those setups too. As a matter of fact a buddy of mine has a set of the 8.3:1 .040 over wiseco/eagle combo with one bad rod (rod bearing spun) with about 40 miles on them for about $250. Im not a fan of used parts, especially internal parts, but thats a big savings if i only have to buy 1 rod and a set of rings! I might have to start a build thread in this thing eventually!

 

[92 GSR-4]

Yep. I bought a BNIB set of JE pistons for $200 shipped. Likewise, I bought a set of Manley rods for around the same price...again BNIB. I'm picky, though, and only want new parts that are unused. So that's the deal I would be waiting out for.

 

[Cool09]

Where did you find those deals?

 

[dsmfergie]

So now that I have been doing some research and have been looking into high performance piston and rod combos. I have found that there are 2 different piston materials, 4032 and 2618.

I have found that the 4032 (mahle, supertech, etc) has less thermal expansion but has limits on power and a tendency to crack ring lands but they tend to be quiet (little to no piston slap) and has more longevity.

On the flip side, the 2618 (je, wiseco, cp, etc) has more thermal expansion and can withstand huge amounts of power but are noisy and I have seen they tend to not last long.

Now being that I will be driving this car in the winter as well in Iowa (some mornings as cold as -10 degrees without windchill), will the 2618 pistons be so cold that piston slap even worse and possibly damage the pistons or worse the cylinder walls? Maybe I am thinking too far into this and searching for something that doesn't exist.... My goal is to be able drive 15k miles a yr and embarrass some vettes and cobras and hopefully that 11.5 i want. I dont really know the hp numbers I need for that, haven't gotten to that point yet, more worried about the reliability part first. Thanks guys!