1G 1g rods/2g pistons HP Limit?

[TurboDSMer]

I was thinking about doing a rebuild on my 6 bolt with 1g rods with 2g pistons and wanted to know what the hp limits would be on that combo. I know that 1g rods are good for up to 500whp but didn't know about the 2g pistons. I heard that the 2g pistons are better than the 1g in strength but didn't know if there was any truth behind this. Thanks Sean.

 

[4pistons]

You have to think differently in terms of "strength" of pistons and rods. Horsepower doesn't usually limit them, nitrous excluded, it's over revving or mechanical failures. Most people equate RPMs with Horsepower and end up with failures.

Over-revving is number one killer of rods. The rods are under incredible stress at top dead center as they change direction and yank the piston back down rapidly. Even more so on the exhaust stroke where there is no compression to "cushion" the piston during the direction change.

Mechanical failures are what usually kill pistons. Valve contact, valve failure, running lean and melting, scuffing the cylinder walls - stuff like that.

So how much horsepower can they hold? Good question. Something else usually kills them first.

Rick - '91 GSX

 

[TSIfreek]

Good post

 

[TurboDSMer]

Thanks for the info, but with that said what would be the max rpm of reving you would suggest for that combo? My head is going to be a SBR stage 5, but i don't want to set my redline at anything that will kill my motor fast. any input on this new question would be greatly appretiated. Thanks again Sean.

 

[project_tsi]

Scat rod/ Wiseco Piston combo. Good price. can't beat em

 

[Hammer_Gaidin]

The rods are pretty decent. I've built a few motors that reved to over 7k quite often (track motors) and the rods never went. As for pistons I would recommend a forged piston. That way you are better protected from heat and blah blah blah...

 

[TSIfreek]

Thanks for the info, but with that said what would be the max rpm of reving you would suggest for that combo? My head is going to be a SBR stage 5, but i don't want to set my redline at anything that will kill my motor fast. any input on this new question would be greatly appretiated. Thanks again Sean.

First off what are your goals as far as HP. What turbo do you plan on running?? Maybe the scat/wiesco combo would be better off if you really what to put some HP down in the future. That combo will set you back about $750 for everything. I am not saying the 2g piston/ 1g rods are a bad combination but I would like to see stronger pieces if I am going to be pushing the motor hard . Remember you are going to spend a good 200 to get the 1g rods race preped and fited for the 2g piston pin. This is the reason I am runnning scat rods they are only 300 and far better maching quality than eagles. All that needs to be done to the rods is have the pin bore on the rod sized for the the piston pin you will be using. IMO its not worth all the prep work to run the 1g rods when you can by a nice forged piece all ready to go and 10 times stronger for another 100.

 

[gixrman]

Thanks for the info, but with that said what would be the max rpm of reving you would suggest for that combo? My head is going to be a SBR stage 5, but i don't want to set my redline at anything that will kill my motor fast. any input on this new question would be greatly appretiated. Thanks again Sean.

Your also going to have other factors that will limit rpms like valvespring float and intake manifold, no sense in spinning your motor past factory redline when the intake won't flow for it. Is this going to be a daily driver? Like 4pistons said mechanical failure from heat/detonation will hinder you more. be more specific on your goals.

 

[4pistons]

If you're still running the Big 16G then your factory redline is plenty. The turbo can't flow efficiently past 6500 rpm anyway so don't stress your engine more trying to wind it out.

its not worth all the prep work to run the 1g rods when you can by a nice forged piece all ready to go and 10 times stronger for another 100

Where did you get that info? The stock 1G rods are beefy forged units already. I had mine machined at Fast Times Motorworks in Morton Grove Illinois. The guy at the shop commented on how sturdy the stock rod is. And he knows racing engines - They build 7, 8, 9 second engines. Aftermarket rods may be stronger but nowhere near 10 times more. This is in no way a slam of aftermarket rods or anyone that uses them. They have their place in hot rodding but I don't think you NEED them on a street motor.

As others have said, a better bang for the buck would be a forged piston rather than an aftermarket rod if you're dead set on spending money.

BTW, I spent about $120 to get all four stock rods machined and the 2G pistons installed.

Rick - '91 GSX

 

[arash15]

no offense, but the 1g rod 2g piston combo is very obsolete. that idea was from the time where aftermarket companies didn't come up with a reliable forged piston. why not spend the money once and know that you wont have any problems or limiting factors with your setup. I mean you got enough money for a slowboy head, but don't cheap out on the bottom end. invest in your motor once and make sure you do it right. but dont get me wrong, the 2g piston/1g rod has very good results and lots of people make some nice numbers with that setup.

 

[TurboDSMer]

The reason that i'm going to do the 1grods/2gpistons is because i have 1g rods and i have 2g pistons that i didn't pay any money for. so why would i go out and buy forged pistons and rods if i didn't have to? I am just trying to get my car back up and running to it's previous state.

 

[TSIfreek]

I would use them then. Just have ARP rod bolts installed, resized, fitted for the 2g pin and rebalanced.

 

[arash15]

The reason that i'm going to do the 1grods/2gpistons is because i have 1g rods and i have 2g pistons that i didn't pay any money for. so why would i go out and buy forged pistons and rods if i didn't have to? I am just trying to get my car back up and running to it's previous state.

do it then man. don't follow the trend and be a little different. you'll still have a kick ass dsm. haha

 

[boostedinaz]

no offense, but the 1g rod 2g piston combo is very obsolete. that idea was from the time where aftermarket companies didn't come up with a reliable forged piston. why not spend the money once and know that you wont have any problems or limiting factors with your setup. I mean you got enough money for a slowboy head, but don't cheap out on the bottom end. invest in your motor once and make sure you do it right. but dont get me wrong, the 2g piston/1g rod has very good results and lots of people make some nice numbers with that setup.

They are not obsolete. The real reason why they aren't that popular is because everyone thinks they need forged everything to make 300 HP. If people actually stated there goals and work with that then they would see that wasting money on forged internals is just that, a waste. I believe the 1G/2G has gone 10's and there are a TON of DSM in the 11's with that combo. When people reach the limit of that combo then they should move to forged.

 

[jmakado]

I have yet to EVER hear of a stock 4g63 bottom end letting go from overreving. The top end is a different story. Your main weakness in running the stock rods/pistons is going to be from detonation. Forged parts can take the abuse of pre-detonation better. If you have the car tuned well and don't try to go to crazy on pump gas you will probably never reach the limit of the stock pieces without a very large turbo. People have made over 500WHP on stock 7 bolts!! I think that a lot of the older "rules" like only being able to handle 450HP on a stock 6 bolt were raised when good tuning units like dsmlink came out. If you have the parts then I would say go ahead and use them and don't be scared of them being brittle little "stockers". Just keep the knock under control.

 

[arash15]

They are not obsolete. The real reason why they aren't that popular is because everyone thinks they need forged everything to make 300 HP. If people actually stated there goals and work with that then they would see that wasting money on forged internals is just that, a waste. I believe the 1G/2G has gone 10's and there are a TON of DSM in the 11's with that combo. When people reach the limit of that combo then they should move to forged.

i know where your comming from. But for that little extra cash you have that insurance in the back of your mind. Its like buying an extended warranty for the engine. so to say. but then again, every engine is different and there are too many factors that can alter the motor. so there isn't really a "general" saying that forged internals are safer, or better than anyother setup. but they do have a very high success rate.

 

[Verticaljump1]

If you don't plan on making more than 500whp than you'll be fine with the 1g rods. The 1g rod/2g piston combo has been proven to be capable of withstanding over 500whp. Strength isn't an issue, tuning is. 2G pistons get the crap kicked out of them if you run excessive knock or too lean. As long as you've got the tuning gadgets from the start you'll be running fine on the 1g rods/2g pistons. If it was me I would just keep the 1g rods but buy myself some forged pistons. By the time you get costs figured out your only paying an addition $350-400 to get brand new forged pistons. Also go with 15:1 compression (, j/k). Just my 2 cents.

 

[boostedinaz]

i know where your comming from. But for that little extra cash you have that insurance in the back of your mind. Its like buying an extended warranty for the engine. so to say. but then again, every engine is different and there are too many factors that can alter the motor. so there isn't really a "general" saying that forged internals are safer, or better than anyother setup. but they do have a very high success rate.

Very true but as many have already said it is all in the tunning. If someone cant tune they will kill forged parts just as quick as the stock stuff. I just don't see the need for someone to go with forged and there only reason is because of what they may do later. Most of the time that later never comes and they waste money on parts that they didn't need. If they break a part due to power, not tunning, then they should upgrade.

This is just my little rant because in everythread that someone ask about building a motor there are always a few people that say you need a, Stage 22 head and 9.0 stoker with forged oil filter do make any power.

 

[TSIfreek]

I like to do it just for insurance and while you have the motor out do it once the best your wallet can afford. I agree I don't need the short block I have but I may someday. We all know we get used to the boost levels we drive around on everyday at and we always find ourselves wanting more boost. I also agree is all in the tune for how long the motor lasts thats just common sense. I just wouldn't run the 1g rods past 25 psi JMO. If you have the 2g pistons and 1g rods use them just make sure you get the proper machining done.

 

[RiceKiller_TSi]

This is just my little rant because in everythread that someone ask about building a motor there are always a few people that say you need a, Stage 22 head and 9.0 stoker with forged oil filter do make any power.

Dont forget the sodium filled nitrided ashtray and titanium radiator cap.

 

[boostedinaz]

Dont forget the sodium filled nitrided ashtray and titanium radiator cap.

Just had them overnighted from Japan.

 

[4pistons]

I just wouldn't run the 1g rods past 25 psi JMO

As I said you have to think differently in terms of rod strength. It has practically nothing to do with boost. Boost or pressure compresses a connecting rod. 99% of rod failures (no, I don't know the exact figure!) are when the rod is under tension, when it reaches TDC and the pistons inertia wants to keep it going out through the top of the engine but the rod switches direction, after rounding TDC, and yanks it back down. On the power stroke after ignition, combustion helps the rod by FORCING the piston down and removing the tension loads. More boost and compression actually helps the rods. The killer is the exhaust stroke where nothing is pushing against the piston and the rod has to absorb huge tension loads. The loads increase exponentially with RPM so you can see that it quickly becomes an issue.

Bottom line is RPM kills. The stock rods will handle any boost you can throw at it.

I have yet to EVER hear of a stock 4g63 bottom end letting go from overreving

I have seen two of them that ventilated the block. One was a shift into second rather than fourth! Ka-POW!!

Rick - '91 GSX

 

[RoasT BeeF]

They are not obsolete. The real reason why they aren't that popular is because everyone thinks they need forged everything to make 300 HP. If people actually stated there goals and work with that then they would see that wasting money on forged internals is just that, a waste. I believe the 1G/2G has gone 10's and there are a TON of DSM in the 11's with that combo. When people reach the limit of that combo then they should move to forged.

Agreed. Its just like everyone thinking they need a 50 trim to run 13's.

 

[1gcrazy]

I am runnning scat rods, far better maching quality than eagles.

Really? Just curious because i was JUST about to purchase a set of Eagles.

 

[dsm-onster]

I would use them then. Just have ARP rod bolts installed, resized, fitted for the 2g pin and rebalanced.

I think this is the best suggestion yet; since the original poster already has the 2g pistons and 1g rods in his posession. Don't most rod failures stem from rod bolts or writs pins letting go? Usually on the exhaust stroke like 4pistons mentioned. Iv'e seen stock 6-bolt bottem ends let go at the bolts (they stretch and flex). How far would the 6-bolt rods have gone w/ ARP bolts?