luanda

For the more sedate FI solutions i.e. staying at say 8PSI, would it make sense to simply swap out the wimpy rods with Pauters or the like but keep the stock pistons?

Would the service cost less? Would the pistons still need to be bored and/or surfaced?

Would the rods alone buy you the strength necessary for prolonged engine life at these more modest boost levels?

Won't the beefier rods actually impact performance i.e. engine response compared to the wimpier hence lighter stock rods? What's the weight difference between say pauter rods and the stock ones??

Anyone?

Dr Bonz

iTrader: (1)

bump for a very good question!

Sharif@Forged

iTrader: (92)

Forging is typically a few grams lighter than casting, becuase you dont need as much material since the forged steel is many times stronger than cast. For F/I, lightness shouldn't be a primary concern...strength is more important. You want something strong and light...but not so light the strength is compromised.

Your question is a really good one. Nissan is known for making pretty durable pistons, and the rods seem to be the weak link. That said, I think the piston RINGS and piston lands are suspect here, given several guys with severly deteriorated compression. Now maybe the wimpy rods contributed to the worn rings..nobody really knows.

But to my knowledge, you need to remove the motor to change the rods anyways, so you arent saving a whole of money here. And if saving money is important to you...then F/I is not where you want to be. I'd rather spend a bit more and get it done right the first time. Hope I didnt sound to arrogant.

Also, I will call Pauter in the morning and ask them how much lighter their rods are vs. stock. The Arias pistons are..I think..about 40grams lighter than stock..each...10% lighter,,,roughly.

Z1 Performance

iTrader: (564)

I cannot think of a bigger waste of time than taking a motor apart to replace rods, and not fortifying the remainder of the bottom end, unless you have a spare, bare block sitting around doing nothing (and even then....)

The sheer time and expensie involved in removing the motor, tearing it down to the block, and then having to reverse the steps is a very costly endeavor, and really should be done if you plan on building the whole motor.

There are plenty of Z's running around with over 400 hp on bone stock internals. I would hardly call the VQ35 rods wimpy - I would however suggest that most tuners dealing with this car (or any other car for that matter) simply don't know nor understand fully what they are doing when tuning the engine management side of things (regardless of what system you are tuning) - there is no greater destroyer of engines than a poor tuner.

You won't notice any sort of performance differences with forged internals vs the stock ones, all other things being equal (displacement, compression, etc). There is absolutely no reason that a stock VQ35 cannot take the kind of power the Vortech SC kit will be putting out at 8 psi, provided you get the right components in the car in terms of fuel (which, Chris, you will be), AND, your tuner fully understands what he is doing with your intended engine mgmt solution.

Adam

luanda

Adam, great feedback as always - Thanks mate.

I guess I am more worried about throwing a rod than I am losing compression. Don't get me wrong - both are major problems to avoid, but once a rod goes through the block that's it right? I mean it's off to Nissan for a new engine. If you lose compression, you can get new rings, pistons etc. do a rebuild and be back in business.....

"better, stronger, faster than before"

Yes / No Maybe???

luanda

gq_626


I'd be curious to hear what the weight differences are..please post your findings.

Thanks.

Z1 Performance

iTrader: (564)

true - that's assuming you throw a rod through the block...a broken rod does not always reveal itself remember

If 8 psi on a Vortech setup (say circa 400 whp) is your goal, it is 100% totally doable on a stock VQ35 - just get the tuning right (since I already know yoru component choice) and you'll be in business.

G3po

iTrader: (8)

8psi on a Cent SC vs a TT place significantly different levels of demand on the bottom end, Given that a TT setup provides significantly higher average and peak TQ stress upon the bottom end.

This would imply that with "psi begin constant" there is more reason to forge the internals of a TT setup than that of a Cent SC.

Also a Root/TS SC at the same psi level places slightly more TQ load upon the bottom end than the TT since the the blower must also be driven by the crank in addition,

joenismo

Stock rod w/bolts weighs 588.5 grams
Pauter rod w/bolts weighs 624.8 grams

Stock 95mm piston w/pin, w/o rings or locks weighs 502 grams
Ross 100mm piston w/pin, w/o rings or locks weighs 500.2 grams

Hope this helps. I am surprised that the pauter rods weighs more, but it is much beffier. One more thing the Pauter rod I am weighing has been E.D.M. driller. I am not sure how many grams that accounts for, probably around one gram.

phunk

iTrader: (21)

you will need to have a rod custom made if you were going to try and use them with stock pistons.

rod manufacturers are not making direct fit rods for the stock pistons. They are going to a 1" pin boss with a boss span of 1.140-1.150". The factory pin boss is tapered. Therefore you could not just take a pauter rod and put a stock piston on it.

That said... your wasting your time putting a stock piston back in the motor. Factory NA pistons are very weak by design. The top ring land is short, has something to do with emmissions and certain gases hiding out on the side of the piston or something... i dont know the details cause im not used to considering emmissions in engine building.

-Charles

Sharif@Forged

iTrader: (92)

Z1, the Vortech guys with proper tuning..even running on the rich side, are still blowing rings. Based on some of anecdotatal evidence on the boards, I'm not convince the VQ can take FI for an extended period of time...even with perfect tuning.

Yes, of course, lots of us are running around at 8-10psi on stock internals with both the TT and SC kits, but that doesnt mean we arent damaging the motoro for the long term. I guess that is my point. I'd be VERY surprised if any of the stock bottom end F/I people's motor last for more than 40,000 hard miles.

I called Arias and they are weighing the piston right now...
Pauter....give me a bit more time.

luanda

So my next question is if you blow the rings / loose compression, are you not better off just building the engine at that point vs. forkin' all the dough out up-front???

Sharif@Forged

iTrader: (92)

Arias Pistons 8.5:1 high silicon 4032 weigh 474g with pin, without rings or locks. So looks like about 28g lighter than stock.

Pauter Rods for the 350Z with rod bolts: 610-620g's

I spoke directly to Pauter and Arias.

This is a mute point....you want strong forged internals for F/I applications, not ultra light stuff.

Sharif@Forged

iTrader: (92)

Yes, if all you do is blow the rings. But there is a huge element of risk there, becuase your failure point could end up being the rod, and not the rings. It's hit or miss. If you snap the rod, it typically results in the total destruction of the motor...not always..but usually.

So its a gamble. Seems like the SC's are blowing rings, and the TT's are snapping rods, since the TT make much much more torque in the lower part of the power band, and hits more forcefully, vs. the linear and smooth progression of the SC.

Z1 Performance

iTrader: (564)

gq - how do we know the Vortec kits were properly tuned though.that's just the thing. I take nothing at face value when people post them anymore.....I ahev seen first hand countless "properly tuned" cars, where people flew tuners in from various parts of the country to tune their setup (whatever setup it might be). Sometimes the results are fantastic......sometimes the results are horrendous.

I think the general concensus shoudl eb that when all is said and done, you are introducing forced induction to a motor that was not originally designed for it...as a result, you run the distinct risk of premature engine failure even with a properly tuned setup, as gq said. However, this does not mean your motoro will fail, just that it can fail, and is more likely to do so than someone who stays NA (again properly tuned).

It's a cost benefit thing though...the guys who are doing the FI route tend to assume this risk knowingly, and are doing it based on their quest for higher performance. They know that the cost of the overall experience can (though it may not necessarily) exceed the cost of the initial install. If you go into this without that basic understanding, you are, IMHO asking for trouble.

tat being said, I have turbo many of my own non tubro cars in the future, with fantastic long term results!

adam

Sharif@Forged

iTrader: (92)

Very well put!

The guy in Orgeon that blew his rings on the Vortech, had his kit installed and tuned by Vortech, when he used to live in SoCal. Your point is well taken..nobody can really know what exactly caused the engine failure, but I still stand by position that forged internals and lower compression can significantly increase the life of your motor, and decreases...but doesn't elminate....the risk of catestrophic engine failure.

Many of the kits that failed where running the standard, out of the box tune and boost levels, so that is really more concerning to me. It is a clear indication that even out of the box...tuning and double checking the tune is a must. IMO.

SQUILL

I couldnt see a bigger waste of money than spending the money for 25-30 hours of labor for a motor rebuild and not replacing the stock pistons.

Keep in mind that if someone actually was to do this then you still have to deal with the higher compression related tuning issues with boost.

Decreasing the compression makes the tuning of the engine much easier and more reliable especially if we are talking about dreadful 91 octane garbage they call gasoline!

remember since the engine is ripped apart at this point you really are pretty much just paying parts costs for the pistons which is looking pretty cheap with the group buy 800+or- plus you are able to increase the boost in the future much safer and easier.

Our engine uses a very strong forged crank so with a set of forged rods and pistons u r all set!

Sharif@Forged

iTrader: (92)

Group buy price on the 8.5:1 pistons are only $596, shippping and PayPal included.


yet another shameless plug.

https://my350z.com/forum/showthread....threadid=85958

SQUILL

holy **** thats cheap!!!! Good work! At that price anybody that wants to build their motor should jump on this bandwagon!
(another free shameless plug)

ether

resurrecting the thread.. coming at this from a slightly different perspective.. how about getting forged rods and pistons but at the stock compression ratio of 10.3.. thinking of this from 2 points, emissions and costs.

a lower compression ratio will have poorer emission results than the 10.3.. here in Japan I have to keep that in mind...

next buying a new block (~$1,200) one could get stock size pistons and not incur the machining costs

Additionally with a 10.3 compression ratio, boost would not be above ~10psi.. the benefit here is limited need for a massive fuel system upgrade (i.e. using the APS fuel system)

i think this could work for creating a rock solid 400whp motor running 9psi, with the benefits of the low end grunt of the stock 10.3 compression ratio.. i realize that 10.3 compression ratio limits huge HP numbers, but if one is not targeting those, and has ready access to high octane gas to keep detonation at bay, this could be another angle..

Does this make sense?