N/A rods question

Innu_Qc

Member
:
Protege ESGT 2001 black
Hi all, I just bought a spare motor to build N/A. I am still at the planing stage and now I am wondering what to do with the rod. I already decided to have the crank knifed edge and balanced along with the rod and piston. For piston I will most likely go with the 10.4:1 set on Corksport, or an equivalent. Now what do I do with the rods.

I can OEM ones shot penned and even cryo-threated. Or I buy some forged ones. I am aiming for a max rpm of 7500. I autocross the car on summers so the rpm can stay at high rpm for extended period.

So my question is, do you think the oem shot penned would be solid enough or should I go for forged one's because they would still be to big?? And also why???

And to make it clear on what motor, I have an ES-GT 2001, 2.0l ;)
 
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just get forged ones they are like 675-750 for oliver and pauter. How much HP do you want? I personally dont want the stock rods anywhere near a built motor no matter what is done to them I would still be afraid of them breaking.
 
A.V.MSP said:
just get forged ones they are like 675-750 for oliver and pauter. How much HP do you want? I personally dont want the stock rods anywhere near a built motor no matter what is done to them I would still be afraid of them breaking.

Most likely, once done it should be around 150-160 whp with ECU, maybe more but I'll be more than happy with that N/A ;)
 
you might be able to get away with the stock rods but your gonna raise the redline so I would to be safe but if tuned rght you could probably be fine. If you start spraying or go FI or are having any thoughts about it then just get a set of rods. I havent seen any one break a rod yet NA
 
What mods (I know, u listed a few, but it'll take more than that to push 150...) are u planning on making?
 
aMaff said:
What mods (I know, u listed a few, but it'll take more than that to push 150...) are u planning on making?
For mods now, I have a complete exhaust line from motor head to rear bumper, the intake side is almost all done also, VTCS removed, termal spacer, light porting on intake manifold. With all that and stock ECU, I am pushing about 110whp.

To get to 150whp I plan on bluprinting, balancing, the block. Port, polish and port match intake and exhaust. 3 angles valves job, custom cams, raising the compression close to 11:1. And most importantly with all that, a stand alone ECU to control everything. Without it and the OEM ECU it would be real hard to get to 150whp.

And for those who wonder how much max rpm I plan on, it is 7500 rpm. I believe the stock valve train should be able to cope with it. I just wonder if I have the rod shot penned, they would be strong enough to cope with extended high rpm in racing situation.
 
Innu_Qc said:
Long time I haven't heard from you, how far is you're build comming :D

Look at my sig ;)

After saying all summer that I won't dump anymore that much money at the same time like this Spring (suspension almost done, etc.), well it's lookin like it will be worse for 2006 lol!

My plan is to 'bulletproofing' all the car before adding power. I'm still confused between NA or FI as always, so this rod question for NA is more than adequate for me in 2007.
 
forged rods.

however, if you REALLY want to do it properly i'd suggest getting the lowest compression ratio pistons you can find and getting longer rods. you're already going to be spending a lot of money on rods so getting custom jobbies wont be much more. also, with the longer rods you'll be able to get the compression ratio you want and you can also go to 8k and probably even more and you'll be FAR safer doing it.

ps - sorry for late reply - busy weekend
 
Yeah, the rods are wink link with the FS to begin with, and even treating the stock rods won't help much. RPM is worse for rods than boost, especially with such a low rod ratio. Jamie(Install) has done the most to remedy this. Not only has he made longer custom rods, I believe he's increased piston pin diameter(correct me if I'm wrong Jamie). But he also needed custom piston with a lower compression height to accomodate the longer rods.

Your valvetrain won't have a problem with 7500RPM; even the hydraulic lifters in the BP are good for 7800. But with the mods you've listed, 150whp seems reasonable.
 
A.V.MSP said:
you might be able to get away with the stock rods but your gonna raise the redline so I would to be safe but if tuned rght you could probably be fine. If you start spraying or go FI or are having any thoughts about it then just get a set of rods. I havent seen any one break a rod yet NA


I just replaced my original motor because a rod broke. I have an oilpan full of chunks of metal.

I am just running N/A with an MP3 ECU, CAI, header, MAM midpipe & Magnaflow catback exhaust with just 116-117 whp.

So I am in the research stages of building a built N/A motor too.
 
correct Josh...I went with larger titanium wrist pins with the final build, from 17 to 19mm...7500rpm is too high for stock rods too...I am only going to safely run 8000rpm with a much higher (relatively) rod ratio...do not bother with "shooting" the rods, its old technology...It isn't a bad idea for questionable surfce problems on some rod builds...but other than that it mostly affects torsional rigidity, and you are looking for more of a inertial strength increase (you do not want the rods to stretch, but you are not going to make much more torque...hence the need for inertial over torsional)...so save the money for a good set of forged aluminum (or steel) rods, depending on what type of rev speeds you are looking for...

but remember NA engines have to be physically strong, and have very efficient tuning...This isn't a case where stock rods will work well as long as the tuning is good...You will make good power with the good tuning, but your reliability will be very poor...and it will just be a matter of a few weekends before it comes apart; I would bet...
 
Innu_Qc said:
Hi all, I just bought a spare motor to build N/A. I am still at the planing stage and now I am wondering what to do with the rod. I already decided to have the crank knifed edge and balanced along with the rod and piston. For piston I will most likely go with the 10.4:1 set on Corksport, or an equivalent. Now what do I do with the rods.

I can OEM ones shot penned and even cryo-threated. Or I buy some forged ones. I am aiming for a max rpm of 7500. I autocross the car on summers so the rpm can stay at high rpm for extended period.

So my question is, do you think the oem shot penned would be solid enough or should I go for forged one's because they would still be to big?? And also why???

And to make it clear on what motor, I have an ES-GT 2001, 2.0l ;)

I would have a problems with the stock rod bolts at that RPM. You can get better bolt, rework the rods but the cost is up there. We do a very light weight rod/piston and crankshaft combo. It is work well for over 320whp. The rods for our engine are way to heavy. With a setup you safe alot of weight and still have a very strong bottom end.
 
MPNick said:
I would have a problems with the stock rod bolts at that RPM. You can get better bolt, rework the rods but the cost is up there. We do a very light weight rod/piston and crankshaft combo. It is work well for over 320whp. The rods for our engine are way to heavy. With a setup you safe alot of weight and still have a very strong bottom end.

how much is something like that?
 
I am not sure how much his combo is, but just rod bolts can range from 100 to a couple hundred for the set of 8 we would need...but that is simply the bolts, you have to strip the entire assembly down to do it correctly (some do it from underneath, but it is easy to torque things incorrectly when you do it this way...I would not do that)...also, some stronger bolts are also thicker, which involves tapping the end caps and big end again to get them to fit properly (and material specialists will start barking about the mess this causes with the rods integrity)...

It is definately not worth putting stronger cap bolts on the stock rods...for whatever reason...the rods themselves are just as bad for high ouput and/or revs...if you get better rods, get good rod bolts to begin with to safe yourself a huge mess in the end...
 
well, i just want to add the following to my car:
cams
hc pistons (10.7:1)
rods
valves, valve springs, retainers
stand-alone

i don't want to go overboard...just have enough to play with.
 

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