Forged pisons in a daily driver?

[Enraged78]

Hey all,

I'm at a bit of a crossroads here, and I thought that I would try to get some input from the group. I'm going to be tearing down my motor in about 4-6 weeks, and I'm trying to decide between the stock 2G 8.5 to 1 pistons, or a set of Weisco 8 or 8.5 to 1 pistons for my 95 TSi AWD. There are a few things that you should know before you reply.

My end goals for the car are as follows: 12.5 in the quarter on race gas. This opens up my choices of turbo to near limitless possibilities. Lets say for arguments sake that I will be upgrading to a 20G over time.

I'm going to be running 91 Octane and have no access to anything better, unless I go to the track, where I will run race gas. This low octance number is something to contend with, and the primary reason why I don't think more than 8.5 to 1 is a good idea.

The tentative parts list for the rest of the buildup is as follows: Full OEM Gasket & Timing parts. Mitsu 4-layer headgasket. Mach V MVCAD kit. Eagle rods, ARP studs for mains and head. Block will be bored .010 - .020 over (depending on measurements taken at teardown), balanced, blueprinted, and will have some mild port work done to the head. Head will be rebuilt as well.

I know that forged pistons in a setup like this might be considered overkill, but I want to hear your opinions. I'm of the philosophy that anything done should be done right, and I don't want to do this again. Right now, I'm only shooting for mid 12's, but who knows when the mod bug will bite again. When the Talon is done, I will be selling my other car, and this will be my daily driver. I am looking to see what the downsides of a setup like this is, including the long term effects of piston slap, or anything else you can think of.

Thanks,

Matt.

P.S. Yes, this is a seven bolt. Please do not mention crankwalk in any of your replies. I am aware of the risks. With 180K on the block, I think I'll be OK.

 

[1fast97gsx]

just get 1g rods and 2g pistons. It's all you need. For a 12.5 sec 1/4 mile you don't really need to even touch the internals, so just do the cheapest thing you can do.

 

[1LE]

I know of several people daily driving with forged pistons and no issues. Probably the most important thing is to let the car get sufficient temperature before putting load on the engine. Also, some forged pistons expand/contract with temp more than others...

 

[Whiteshadow]

If you go ahead and buy new 2g pistons and 1g bigrods you might as well just get forged pistons because new 2g pistons cost about 20 dollars less than a set of forged ones do, unless you find some for cheap. Which would you rather trust when you feel like turning the boost up? I put in 8:3.1 wisecos and everything seems fine so far. Almost the same CP as a set of 2g's...Young jedi the answer lies within, use the force

 

[1fast97gsx]

If you go ahead and buy new 2g pistons and 1g bigrods you might as well just get forged pistons because new 2g pistons cost about 20 dollars less than a set of forged ones do, unless you find some for cheap. Which would you rather trust when you feel like turning the boost up? I put in 8:3.1 wisecos and everything seems fine so far. Almost the same CP as a set of 2g's...Young jedi the answer lies within, use the force

2g pistons are $200... 1g rods you can find on the classifieds for less than $100 as well. With all the stock stuff you don't have to worry about piston slap and it's a proven combo. Why go overboard?

 

[1fast97gsx]

I know of several people daily driving with forged pistons and no issues. Probably the most important thing is to let the car get sufficient temperature before putting load on the engine. Also, some forged pistons expand/contract with temp more than others...

I agree with you... I have forged internals as well. However if you only plan on running 12.50s then changing the internals is totally not needed. Just get the $500 engine rebuild kit from slowboy racing and slap on a 20g and you'll hit those times ...

 

[eclipse90gsxt]

1G rods/2G Pistons will be fine for 12's. Evo16G is all you probably need as a turbo also.

 

[Mike 99GSX]

Well since he owns a 2g, he already has the 2g pistons guys.

 

[paul s]

I have a 2g(7bolt) with Ross pistons/eagle rods drive it everyday for the last year running low 12s anyday/all day on 22psi and no problems at all, the car is driven everyday..

 

[1fast97gsx]

Well since he owns a 2g, he already has the 2g pistons guys.

yea but he mentioned wanting to bore the block....

 

[blue1]

Wiseco's run an offset pin which also keeps things a lot quieter aswell.

 

[Enraged78]

First off - Thanks for all of the replies, guys. I appreciate the feedback.

The 1G Big Rod/2G piston combo will cost me the EXACT same amount of money as a 2G piston and Eagle rod setup. This is because I have to get new pistons and rods (because of the overbore), and because the 1G big rods need to be machined to mate to the 2G pistons. I also am not sure I want to trust used 1G rods. I would have to buy them new. A slightly bent or cracked rod would ruin this whole buildup. New 1G rods are about $200.00 new, and another $100.00 to have them machined. Eagle rods are the same price, $300.00

Going to forged pistons on top of that is only $150.00 extra. 2G pistons for the .010 - 020 overbore are about $200.00. Weiscos are about $350.00

So, basically, I can either do 2G pistons on Eagle rods, and save $150.00, or I can go all forged. For the little amount of money we're talking about, I can REALLY make my 7-bolt bulletproof.

What I really wanted to hear about, and have from 1Fast97, WhiteShadow, and Paul S, is that there really are people out there running forged, daily driven, 7 bolts. And you guys are running these motors hard, with no ill effects.

That's the best news I've heard all day. If anyone has any more input on a daily driven, forged, 7 or 6 bolt, please feel free to add to the discussion. If anyone has any other input, please also feel free.

To narrow this down a little bit, has anyone else run the Weiscos daily? I'm hearing a lot of great things about both the Ross pistons and the Weiscos, and I would love to know if there is any real difference between them. Are they both offset pin pistons? Which has a higher silicone count?

Thanks,
Matt.

 

[1fast97gsx]

yea I believe the crankwalk thing is way overrated. I have ross pistons and eagle rods in my car with an scm61 turbo. Although the car is not a daily driver ( because of gas mileage and likelyhood of me doing something stupid ), it does have plates and insurance and is street legal, and crankwalk isn't my primary concern although I do have a 6 bolt motor in the making in a stand.

People with forged internals sometimes complain about piston slap, or some people claim that they won't last as long as the oem stuff. I don't know what to tell you about that ... I think it would hold up just as long and if the machining was all done right it shouldn't give you any problems. Just let the car warm up and let it cool down and I think you'll be fine. So far ross pistons are the ones I've heard best things about so those are the ones I'm using. In the past I think it was magnus .. not sure ... but someone posted that the wiescos were giving them problems and they didn't recommend them. I forget who it was though. Either way, whatever you choose I'm sure you'll be happy and it'll be good for 12s no doubt with a decent turbo and intercooler.

 

[1fast97gsx]

here is a quote from the site :

"Firstly the pistons (which shall remain nameless) had insufficient clearance, this not being the fault of the builder, but of the piston manufacturer, they claim .0035" is all the clearance their pistons need. I find them to be a bunch of morons and will not use their pistons again. Customer service was horrible, they of course stand by their story. My question is this, A small block chevy that make 250 hp on 8cyl and 5L can probably run .0035 wall clearance on a forged piston, but a 250hp 4cyl 2L, that experiences double the cylinder pressure should not run these tight clearances, It must run at least .005", the heat generated will expand the piston a lot more. From now on we will only use ROSS pistons."

Obviosuly they didn't name the pistons .. however they said they are going to stick with ross pistons ... 1 point for ross

 

[heavyD]

I've got Arias racing pistons in my daily driver. The only thing I notice from my rebuild is a little vibration from the balance shaft removal. What's this piston slap you guys are talking about?

 

[1LE]

I have JE pistons and also have zero piston slap. Probably about 35,000 miles on them so far.

 

[paul s]

I have no balance shafts but the engine was balanced, I use 272/272 cams with fidanza flywheel and UR pullies the engine vibrates very little at idle...

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here is my set up.. btw i also have ARP main studs..also have very little piston slap, only on cold mornings for few minutes till things warm up..

 

[loreak]

here is a quote from the site :

"Firstly the pistons (which shall remain nameless) had insufficient clearance, this not being the fault of the builder, but of the piston manufacturer, they claim .0035" is all the clearance their pistons need. I find them to be a bunch of morons and will not use their pistons again. Customer service was horrible, they of course stand by their story. My question is this, A small block chevy that make 250 hp on 8cyl and 5L can probably run .0035 wall clearance on a forged piston, but a 250hp 4cyl 2L, that experiences double the cylinder pressure should not run these tight clearances, It must run at least .005", the heat generated will expand the piston a lot more. From now on we will only use ROSS pistons."

Obviosuly they didn't name the pistons .. however they said they are going to stick with ross pistons ... 1 point for ross

ok im about to have my machinist build my motor for me, and this is of interest to me. How much cylinder wall clearance should i tell him to set it to.

 

[1fast97gsx]

some piston manufacturers already account for it in the ".020" and some don't. Ross already does so just bore it .020 over stock and that's it.

 

[Omega]

It sounds like your engine is fine as is. Is there any perticular reason you are going .020 over?

You are wasting your time if you think that the extra dia will make a noticable difference. If the block and pistons are fine then just pick up the rods and spend that saved money in another part of the car.

 

[JiveMasterT]

It sounds like your engine is fine as is. Is there any perticular reason you are going .020 over?

You are wasting your time if you think that the extra dia will make a noticable difference. If the block and pistons are fine then just pick up the rods and spend that saved money in another part of the car.

i agree with this in some respects.... i mean, if your plan is to slap a massive turbo on there, then i would say to go with the overbore because it will help a bit in getting the damn thing spooled. when i do my engine rebuild i will be doing 1g rods, 2g pistons, and leaving everything else stock. i plan on running this setup with 17psi on the street and 20-22 psi at the track. i believe with the proper supporting mods, the stock block is good to go. one other thing you might want to look into is evo8 internals. i dont know if they will fit in our car though, but i know they were designed to be daily driven and run at 19.5 psi.

 

[sunflashx]

ok im about to have my machinist build my motor for me, and this is of interest to me. How much cylinder wall clearance should i tell him to set it to.

If he's a competant machinist, he should be able to figure it out on his own from the instructions that come with the pistons. For reference though, it should be in the .005-.006 thousandths range.

My Ross are .006 and don't seem to slap at all. They are from Magnus though, and have an offset wristpin. I'm not sure if the normal shelf stock Ross are setup that way.

 

[Enraged78]

It sounds like your engine is fine as is. Is there any perticular reason you are going .020 over?

You are wasting your time if you think that the extra dia will make a noticable difference. If the block and pistons are fine then just pick up the rods and spend that saved money in another part of the car.

The .020" is an approximation. The engine has already been built once, and I am not installing forged pistons into a block that is just honed. The motor is being pulled this weekend, and after it is ripped apart, we will be measuring the current clearances and checking the cylinder walls for any imperfections. If any are found, we will measure their thickness and bore accordingly. If we have to, we can go over .020". If we don't find anything, then we might just go with a .010" overbore, so we can save some room in case there is a 'next time around'. I realize that the extra displacement offered by the overbore isn't really buying any extra power, but it does make sure that the pistons and block are perfectly matched for each other. You are perfectly correct, though. The overbore isn't buying me any power.


Thanks,
Matt.

 

[Enraged78]

i agree with this in some respects.... i mean, if your plan is to slap a massive turbo on there, then i would say to go with the overbore because it will help a bit in getting the damn thing spooled. when i do my engine rebuild i will be doing 1g rods, 2g pistons, and leaving everything else stock. i plan on running this setup with 17psi on the street and 20-22 psi at the track. i believe with the proper supporting mods, the stock block is good to go. one other thing you might want to look into is evo8 internals. i dont know if they will fit in our car though, but i know they were designed to be daily driven and run at 19.5 psi.

I'm already running those boost levels on my daily driven factory motor. I'm planning on making around 400HP on pump gas (not with this turbo, of course), and to do that reliably, I need to go forged. My theory is anything that's worth doing is worth doing right, and I don't want to do this twice. As far as the Evo 8 internals go, I haven't looked at them. I have been told by many people that for my setup, the Eagle Rods and Ross pistons are the way to go. Both my engine builder and my parts supplier have said what has been echoed in this forum. With that many references, and such a large amount of people working with this proven setup, I think I'll go that route. So far, eveyone has pretty much told me the EXACT same thing. Ross pistons (bore depending on measurements taken at teardown), Eagle H-beams, Ralliart HG, and ARP hardware throughout are good for one hell of a DSM motor. I'm not knocking Weisco's in any way, in fact I'm kind of partial to them, especially since one of their engineers patrols this forum in a very positive light, but both my engine builder and parts supplier have said Ross pistons, and it seems that the people on this forum have had great results with both pistons. With those odds, I'll stick with Ross.

This is why a resource like DSMTuners is invaluable. Because of the advice from people in this forum, I can go with a trusted and proven method to building a well balanced street/strip motor.

Thanks,
Matt.

 

[loreak]

i just got my ross 8.5 .020 over pistons today, and arp rod bolts, im heading down to the machine shop tomorrow i cant wait to get everything done and get the car back on the road

my old pistons were shot, and it almost seemed like someone bored the block and used the stock pistons, there was a very large amount of slop side to side, but ive never had another one apart so i dont know how its supposed to be, i could move the pistons side to side quite a bit