ECOTEC and T20SED

Nubira2.2 · Post by **Nubira2.2** » Tue May 31, 2005 6:27 am

Does the ECOTEC pistons and rods fits the T20SED engine ?

Can anyone mention the difference between the engines

Post by **PrecisionBoost** » Wed Jun 01, 2005 5:15 am

Well...... I'm going to open up a can of worms.....

I was keeping this a secret since I was going to use the forged ECOTEC pistons in my high horsepower engine.... but now I have changed my mind so I might as well let everyone else know about my findings.

I will say this right now...... I take absolutely no responsibility for those who try using the ECOTEC piston/rod in their T20SED/U20SED/C20XE.... do this swap at your own risk

Will the American ECOTEC pistons (sunfire,cavalier) work in the T20SED??

Yes.... I have a set that I got from a guy who had water in his engine.

Three out of the four have broken connecting rods and two of the pistons are destroyed but I managed to make one good rod/piston combo.

There are some significant differences between the two engines..... they are nothing alike.... but luckily the connecting rod/piston combo is useable since they both have an 86mm bore.

I don't have the specific information for the T20SED but I did have a C20GET to compare with.

I belive that the total length from the center of the connecting rod to the top of the piston is very close between the T20SED and C20GET (if not identical)

The C20GET has a decreased compression as it has a very large "dish" in the center of the piston.

OK..... Here are the numbers....
Con Rod Length Comp Height TOTAL HEIGHT
C20GET 5.650" 1.185" 6.835"
ECOTEC 5.765" 1.053" 6.818"

So although the ECOTEC has a longer rod the piston pin is much closer to the surface of the top of the piston (compression height)

So..... overall the ECOTEC pistons are only 0.017" shorter than the C20GET.

This will decrease compresion slightly but the ECOTEC pistons can be ordered with all kinds of different compression ratios to make up for the difference.

I put the numbers into a calculator once but I forget how much is changed the compression ratio..... I think it only dropped it 0.5

What I did was use a standard calculator and simply made the "gasket thickness" 0.017" thicker to see how much the compression would drop.

So..... there you have it..... have fun... but don't blame me if things don't work out.... you have to do your own homework and make sure I'm right on this.

I should have the connecting rods and pistons from my U20SED (suzuki forneza engine) out fairly soon.... hopefully within a month or less.

At that point I will confirm the exact dimensional differences.

kinkyllama · Post by **kinkyllama** » Wed Jun 01, 2005 6:03 am

Erfinder@PrecisionBoost wrote:
I should have the connecting rods and pistons from my U20SED (suzuki forneza engine) out fairly soon.... hopefully within a month or less.

At that point I will confirm the exact dimensional differences.

Out for what?

debo890 · Post by **debo890** » Wed Jun 01, 2005 2:10 pm

i have mine out. also i have the c20ne engine all dismantled. if the c20ne is the same as the c20get then the rods and pistons are most likely the same from looking at it. right now my machine shop is measureing the two. the c20ne rods look more beefy than the nubi's although the nubis look wider. also, i have parts of the c20ne that i dont need, so PM me if any one need parts.

mocpac · Post by **mocpac** » Wed Jun 01, 2005 3:26 pm

this is not a chrismas time but let share this with all...

gm sport compact performance build book

can you use the Cobalt Super Charger in the nubira/leganza etc etc... aparently yes.

Post by **PrecisionBoost** » Sat Jun 04, 2005 2:44 am

kinkyllama wrote: Out for what?

C20LET Connecting rods, ARP bolts, custom machined forged JE Pistons, ARP head stud conversion, cometic head gasket and a few other goodies.

SAFC-II (installed allready), MSD DIS-2 programable ignition system, neon coil pack, precision boost ignition coil adapter.

Then turbo manifold, T3/T04 turbo, intercooler

I'm also considering a GT28RS with a T3 flange (fairly new) but I dont' know if I want to spend that much on the turbo.

I will probably get a cheap T3 or T3/T04 and see how I like it.... if it doesn't spool up at low RPM or exhaust gas temp is too high I will sell it and buy the GT28RS.

End result......18psi.... 300 hp at the wheels (hopefully

)

mocpac · Post by **mocpac** » Sat Jun 04, 2005 3:11 am

cobal 2.2 bore86.008mm stroke 94.6mm compression 10;1 2.0 bore 86.008 mm compression 9.5;

nubira/leganza is bore 86.00 mm

debo890 · Post by **debo890** » Sun Jun 05, 2005 4:54 am

Erfinder@PrecisionBoost wrote:
kinkyllama wrote: Out for what?
C20LET Connecting rods, ARP bolts, custom machined forged JE Pistons, ARP head stud conversion, cometic head gasket and a few other goodies.

how much was the je pistons? also, are you sure the c20let rods will hold 300whp i thought it was a max of 270 flywheel hp(correct me if i am wrong)? why are you not trying the ecotec piston and rod combo? would'nt that be a stronger combination? from what i have gathered up, the con rod jounral and pin journal are smaller than the c20sed. so the machine shop can increase it ok. but i found no detail on the thickness of the conrod journal to fit the crank. can you give me thoes numbers please.

Post by **PrecisionBoost** » Sun Jun 05, 2005 7:15 am

The JE Pistons are blanks.... they have to be machined to my specifications.... and price.... I got them secondhand so they were around $400

The C20LET rods should take 300Whp with the treatment I'm giving them.

I've seen C20LET's running with 325bhp and stock bottom end.

Basicly the rods will need to be deburred, shotpeened and polished to ensure that there are no surface irregularities that could cause stress.

They are used rods so they have allready been heat cycled for several thousand miles.

As for the ECOTEC..... I guess I missed mentioning that about the connecting rods..... they are thinner on the bottom end.

As for the Pin.... well.... I would match them with the ECOTEC pistons so pin diameter is of no concequence.

The con rod journal is identical..... you might have been looking at the ECOTEC drag racing ones.... which use the smaller honda journals (must be used with the steel crank and race pistons)

C20GET connecting rods (measured)
Big end width = 1.037" (26.34mm)
Crank hole = 2.047" (52mm)

ECOTEC connecting rods (measured)
Big end width = 0.866" (22mm)
Crank hole = 2.047" (52mm)

Crower ECOTEC connecting rods (their specs)
Big end width = ??? not shown
Crank hole = 2.047" (52mm)

I was going to get some ECOTEC forged pistons and have a set of Crower ECOTEC rods custom made with a thicker bottom end width.

I was also considering the idea of getting some ECOTEC rods and modifying them to make the width larger.... not exactly sure if you can do this or not.... I did not pursue it any further.

The C20LET rods and JE blanks were way less money..... $600 at my door.... the other route would have been closer to $1600

debo890 · Post by **debo890** » Sun Jun 05, 2005 10:35 pm

those blanks are from tom right? the standard size ones? if not standard size 86mm, where did you get the oversize? also, if i want to use the ecotec pistons, is there any modification that would be needed?

Post by **PrecisionBoost** » Mon Jun 06, 2005 12:48 am

You must use the ECOTEC pistons with the ECOTEC rods..... the ECOTEC pistons will not work with the Nubira/C20NE/C20LET rods.

You need a total length of 6.835"

If you threw an ECOTEC piston onto a C20NE rod you would get the following....

C20NE crank center to pin center = 5.650"
ECOTEC pin center to top surface = 1.053"
TOTAL LENGTH =6.703"

So your piston would end up about 0.132" below the deck surface giving you some unbeliveably low compression ratio.

If you started with 10:1 ratio pistons I'm guessing that you would end up with a compression ratio in the range of 7.5:1 to 7.7:1 ratio

This is far too low for even a high boost application and you would end up making way less power than you would with the regualar 8.5:1 ratio C20LET pistons.

Unfortunatly I can't find my ECOTEC pistons measurements ( I have about 1000 pages of "research" on the engines and transmissions) but I think that they also have a slightly smaller pin diameter... I think the ECOTEC used a 20mm pin instead of a 21mm like the C20GET/LET/NE

Yes.... the blank JE's were from Tom... he was going to use them but he got a great deal on a complete set of C20LET rods and pistons from the UK so he doesn't need them.

And yes.... they are an 86mm bore....my Forenza engine has 9000 miles on it so it's practically new.