3rd gen rods in a 4th gen, ive been told it works, but to THESE pistons? Options

[easternpiro1]

Hi all, as some of you know i am currently in the process of rebuilding a st215 motor. it was necessary to deck and bore the block .20 over and replace the stock st215 pistons with some JDM oversized caldina pistons (toyota brand) according to some guys on mr2oc.com the part number is: Piston kit (0.5mm oversized) : 13103-88580 which i saw referrenced to here: http://www.mr2.com/forums/turbo-engine-tal...er-request.html


Herein lies my dilema... Its been suggested to me to replace the rods due to the fact that the fourth gen rods are a weak point in that engine. the rods from the 3rd gen are known to be beefier.


the question is will they:

1. Fit into the 4th gen
2. attatch to the piston


ive found this VERY interesting conversation: http://s4.invisionfree.com/lexusaltezzaclub/ar/t11717.htm

but it still dosent answer my question fully...


Cuts the pilot is a BIG opponent of the 4th gen rods. (he says theyre made of cheese ) however by good buddy camshaft cam (boosted185) says that teh 3rd gen rods wont fit. I havent been able to find anything...



any help would be greatly appreciated!


cheers!

This post has been edited by easternpiro1: Aug 10, 2011 - 5:14 AM

[ST205WRC]

as far as fitting the crank yes they will. all 3s' share the same crank. the piston im not sure if you whould have to have them machined or not. the beams pistons are more narrow in the area where the rod goes in. so it has to be machined to fit. but machine work or not i would say it is worth it if the rods are as weak as people say they are. i have a set of gen2 and possibly gen3 rods available pm if interested.

[Cuts_the_Pilot]

*weighing in 130lbs*.......

The ST215 and ST205 cranks are the same. (caldinas get higher compression from having a smaller combustion chamber, so the head is whats different here).

ST185 and ST205 rods are the same.

ST205 rods have been proven over here in many 300kw+ atw cars up to 8000 rpm since they are beefy, i dont push my luck too muc though and limit it to 7700.

A couple of guys i know have caldinas and they have thrown legs out of bed (rod out of the block) at 220kw atw and less.

This post has been edited by Cuts_the_Pilot: Aug 12, 2011 - 3:11 AM

[Neon90424]

yes, Caldina rods are made of cheese, 205 rods can be used as dumbbells definitely very beefy the eagle rods seem like pencil sticks compared to the oem rods

[easternpiro1]

ok im sold! so in addition to the rods, i would need new rod bolts and rod bearings right?

and cuts so youre saying since 215 and 205 pistons are the same, and cranks are the same, they should naturally be able to interchange rods? although the beams rods that come in the 215 are much smaller?

what would be a good price for some 205 rods?

This post has been edited by easternpiro1: Aug 10, 2011 - 11:16 PM

[Cuts_the_Pilot]

the part numbers for the pistons on toyodiy different

It would be wise to get new rod bolts either OE ones (if your not going too serious on the build) or some ARP ones if you're boss

As for price im not too sure but it shouldnt be too hard to source some. If you can be bothered (and i would if i were you) ide get them shot peened and obviously balance the whole rotating assembly.

Eagle rods being what they are is the reason i didnt buy them and stuck with OEM. When i do a more serious build ill use something like carrillo or spool.

This post has been edited by Cuts_the_Pilot: Aug 12, 2011 - 3:10 AM

[easternpiro1]

thanks man! will do! I saw how much the ARP rod bolts are, actually pretty reasonable...($40 IIRC)
I also researched shot peening, but never saw a solid price for doing it.

the part numbers on toyodiy are the same and ive also been told they are the same.
The rods are the same size at each bearing but smaller in the middle.

It would be wise to get new rod bolts either OE ones (if your not going too serious on the build) or some ARP ones if you're boss

As for price im not too sure but it shouldnt be too hard to source some. If you can be bothered (and i would if i were you) ide get them shot peened and obviously balance the whole rotating assembly.

Eagle rods being what they are is the reason i didnt buy them and stuck with OEM. When i do a more serious build ill use something like carrillo or spool.

[easternpiro1]

what about the wristpin? Cam says the overall lenght of the rod from midpoint from crank journal to midpoint of wristpin have to be the same between the 215 and 205h

basically, are the st215 rods, and 185/205 rods all the same height?

This post has been edited by easternpiro1: Aug 11, 2011 - 11:34 AM

[Neon90424]

beware if you buy 3sgte ARP rod bolts they will not fit eagle rods I have a fancy box of expensive bolts with my fat paper weight rods eagle rod bolts are thinner and shorter

This post has been edited by Neon90424: Aug 11, 2011 - 4:33 PM

[pitcelica]

Here is some more information. I'm sorry for Cuts_the_pilot, but I will prove you wrong.

Here are the part numbers for ST215 pistons and ST205 pistons, they are different :

http://www.toyodiy.com/parts/p_J_2001_TOYO...DWMZZ_1301.html
http://www.toyodiy.com/parts/p_J_1998_TOYO...BLMVZ_1301.html

Here are some pics or ST205 and ST215 pistons and rods side-by-side with some measurement (credits goes to DeamonSlayer on MR2OC for the pictures) :










As you can see, the ST215 have a thinner small end and the ST215 piston internal dimension to accept this rod end is small too. So, I'm not sure you will be able to use ST215 pistons with ST205 rods. I suggest you to invest in some forged 9.0:1 ST185-ST205 pistons if you want to still use your ST205 rods.

Sam

[easternpiro1]

SH!T...FCUK...DAMN.... UGH!


wow! Great info! thanks pit! i cant get any of the forged 185 or 205 pistons because the block has been bored/honed and due ot the fact that its now .20 over some slightly larger st215 pistons have been purchased from toyota.


seeing the size comparison has made me even more nervous...

guess i will have to stick with the 215 rods and take it really easy!

[easternpiro1]

also got some info from our friends at MR2OC



http://www.mr2oc.com/showthread.php?p=4781204#post4781204











now heres my next question... WHY IN THE HELL would toyota put N/A rods in a TURBO MOTOR?!? (besides the fact they want quick spool and its higher compression...)

This post has been edited by easternpiro1: Aug 12, 2011 - 12:29 AM

[ST205WRC]

most machine shops should be able to mill the couple mm thats is need to use them.

[PhoenixTech]

Aside from all of the useful information on rod and pistons sizes in this thread, this is getting blown way out of proportion. Matt, you want a reliable fun car. right? So we put everything back together with the new pistons, and set her at 14-16psi. That will be a fun reliable Celica. All this talk of bigger stronger rods for that low of boost level is not necessary.

Sidenote: Personally, I'm loosing more and more respect for the ST215 engines day by day. They are not powerhouse engines. They are an OE Turbo engine that, obviously, was not engineered with the intention of putting down horsepower numbers that will sit you on your ass. If you want a high horsepower 3S, buy a Gen2. It will cost you less money to do the shimless bucket conversion and throw on a better turbo, than blow up 2 or 3 ST215s and keep replacing them. Just my $.02.

[bsamps4]

But what about the 205??? Very capable of becoming a powerhouse motor!

[presure2]

IMO i'd just get a set of 3rd gen rods, have weisco or whoever make you a set of pistons to match the 4th gen compression ratio, and be done.
aside from the 4th gen rods, everyone knows the next weakspot is the stock pistons.
at least that way, when you DO wanna turn up the boost, you have what you need to do just that, without any worry of the stock pistons cracking a ringland, or whatever.
with the extra hassle involved in getting a set of 4th gen OEM pistons, im not quite sure why you didnt do that from the beginning.

im not sure what the OEM pistons cost ya (i know 5s ones are ~ 75$ each, so i'd imagine ~300$ or so for the set) but at that point, add in the extra 100$ for rings, and your almost at what a set of wiescos, CP or whatever forgies would cost.
but meh, its all just opinions, and you know what they say about opinions...everybody has one..lol