OK so a recent compression test showed 210-209-180-210 and I have 96,000 miles on the car, im having alot of trouble deciding what to do but one thing is clear, the motor in the car will not last for too much longer without breaking something. My other thought was to ditch everything and just get a cobalt.
Now if I rebuild theres a few things I can do, im not sure if i should go with as high of piston size as possible, I know if I was to get the Darton sleves im good to 87mm bore which im told is about 040 over. Now on to compression I'm not sure how high to go on this I know that with superchargers I can go higher, so I was thinking maybe like 11:0 or something, i most certainly wont go below stock compression.
How does higher comprssion work with boost and how good are the after market parts? I mean how well are wiseco pistons and can I expect to see better durabilty numbers at 200,000 miles
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
wiseco are very good parts and as for durability its proly the rings or the bore itself that is leaking and with any performance car you are gonna have more wear than a stock.. so imo if you want 200000 miles leave it stock.. but if you want performance you gonna have to make a small compromise.
Rodimus Prime wrote:i most certainly wont go below stock compression.
Always entertaining posts from your side of the interweb...
fortune cookie say:
better a delay than a disaster.
Hey Bro,
Well... see I can see the small situation you're in. I'm sure you saw how that built/lower compression LD9 with the GM charger turned out... he's making less power than before - and it's not encouraging... there are a few things to consider when building an engine.
What kind of gas do you plan to run it on? A lot of problems can be taken care of via octane, the question is how deep are your pockets? How well can you tune?
Aftermarket pistons have the advantage if you heat coat them, and of course for an LD9 the improvement comes with the stronger H-beam rods... it sounds to me like your rings aren't holding as they could be....
In all honesty as mentioned above building a "performance engine" that "lasts" is almost contradictory... but it's possible. It's what I did. The problem with this approach is the ridiculous cost and time needed to do it on an LD9, but you're starting in a better spot with the ecotec.
How much power do you want to make? Realistically...
As you know most people drop compression to make it easier and safer to tune the motor, at the cost of power in the engine of course. All of this can be countered with air cooling and water injection and higher octane gasoline, as well as reduced timing... anything to keep cylinder temperatures down. I know Yasmin ran I think a 10:1 built LD9 with boost but from what I remember he had a hell of a time dealing with getting it to run without pulling timing....
If you want to run it on low boost (in and around or under 10 psi) then I don't see the harm if you just step up the octane or - in your case - safely pull timing with boost. Don't go crazy with the compression ratio, but bring it up a bit if you like. It WILL be a bit more difficult to tune but nothing is impossible with the right tools and knowledge.
I say if you want an Ecotec that lasts, get the best parts you can, GOOD rings, have a good rebuilder machine and assemble it properly, break it in 100% and run it well short of its power limit. I don't see why you can't have the motor last a long time on boost so long as you do it right and tune it right.
Good luck man.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Sounds good chris...
Thats what I am doing Matt... I got a very mild build but am running the motor at well below its limit to make it last longer...
LE61T PTE6262 Powered 
I dont see why a build motor wouldnt last any longer then a stock motor........ as long as u dont push its limits you should be good for a long time. a stock eco is always gonna last longer then a stock eco puttin down 270hp to the wheels. put rods, pistons and do a lil head work and you should be good. just dont cut corners by trying to reuse any parts from the motor. anything and everything should be replaced when rebuilding a motor
tuning is 90% of reliablity,
HP Tuners | Garrett T3/T04B | 2.5" Charge Pipes | 2.5" Downpipe | 650 Injectors | HO Manifold | Addco front/rear | Motor Mounts | HKS SSQV | Spec stage 3 | AEM UEGO Wideband | Team Green LSD | FMIC | 2.3 cams | 2.3 oil pump swap | 280WHP | Now ECOTECED
i was looking into the zero gap rings a while back but im not sure about compatibility and such, know jbody performance sells them thats prob the only rings id want
I'll admit my knowledge of internals is lacking somewhat, but I have a limited amount of boost that I can run so I need to find other ways to bump up the power, easiest solution is upping the compression and displacement, but i dont know what reactions it has specifically, I run 93 octane all the time with 50/50 water methanol mix, i mean i cant run race gas all the time to drive to work lol, i can pull timing out if i need to I have Hp tuners
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
good luck with the build Matt.......
SPD RCR Z -
'02 Z24 420whp
SLO GOAT -
'04 GTO 305whp
W41 BOI -
'78 Buick Opel Isuzu W41 Swap
I think what you are considering is a GREAT idea!! I have for some time thought of running a stock, or higher compression motor with boost. As stated already tuning is the key. If you go with forged internals, good rings, good head gasket, head studs no reason you can't do it. If even stay stock compression. With that and your current boost settings the motor should last long time.
FU Tuning
Well heres the plan from top to bottom well actually the other way around
Stock Block, possibly a 2.2 from 07 would be perferred since that has the new revisions
Stock Crank , just balanced
Eagle Rods
Darton Sleves they go up to 87mm bore
Wiseco Pistons big as I can get them hopefully 87mm at least 10:1 comp
Total Seal Zero Gap rings
Stock head gasket
Patriot Stage 2 head
Comp Cams boost cams
Im not about the durability of such a thing with that stuff and less than 10 psi
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
sounds like a pretty stought build........
I lean towards knife edging the crank, balancing the rotating assembly, and a Cometic Head Gasket.......
SPD RCR Z -
'02 Z24 420whp
SLO GOAT -
'04 GTO 305whp
W41 BOI -
'78 Buick Opel Isuzu W41 Swap
I agree with Brian. Also... why are you going with total seal rings? I've had 2 friends use them thus far and they haven't seated properly... not that it speaks for ALL of the companies line of products but it's the main reason I shied away from them for my build.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Is it because weisco sells the total seal rings???
weisco is in ohio up in painsville..
come get them instead of shipping..
horsepower is how hard you hit the wall, Torque is how far you push the wall with you
I would also recemmond if your building a motor balance it all. Also why not upgrade the head gasket on the build? That with higher copression will be your weak link, and maybe the most important link.
FU Tuning
i doubt that head gasket is weak, has anyone ever even blown one? Ive also heard of some of the higher horsepower ecos having trouble with the cometics
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
Get a Honda if you want to be fast.
*Flame suit on*
i personally think that getting your stock head worked is much cheaper, was for my build.
id rather run 19 sec 1/4s than drive a little ugly shoe rustbucket
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
I have thought about going the same route and upping the compression once the damn car is paid off and its not my daily driver. I know that a former J-BOM memeber was building his LD9 with an M45 with higher compression somewhere around 10 to 1 with a ported and polished head with modified H.O. cams and a smaller pulley. If I remember correctly he had a problem with his car and was rebuilding it again. I am very interested in seeing what his car will do as I have maxed out the little M45 and want more. As long as its tuned correctly I can see it yeilding some gains with the RSM setup you have and above mentioned mods. Or you could do the other thing Ive thought about doing and sell the charger setup and go turbo.
Rodimus Prime wrote:i doubt that head gasket is weak, has anyone ever even blown one? Ive also heard of some of the higher horsepower ecos having trouble with the cometics
I would at least run ARP studs to give extra support around the head gasket. I guess this is just me. In my head I'm thinking raising compression and having boost with stock head gasket = bad idea. It looks like you are going all out on the block, maybe even over board, but leaving a important part out.
FU Tuning
oh yea def the studs forgot about those
Im never going to get more than 8-9psi out of my setup even if i did get the stage 2 pulley im not sure if you can do that on something like an 11:1 compression pistons and 93 octane, would prob have to kill a huge amount of timing and the EGTs might be so hot it wouldnt be worth it, I might be better off with stock compression just bored out
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
if that is all ur gunna run for boost don't lower the compression hell it's built for stock so why would any one lower it. With such low boost maybe just bore it over .040 and up the compression to 10.5:1 its is a decent increase. as long as it is tuned right it will be fine you have the added benfit of forged pistons wihch run cooler normally anyways. With a nice flowing head and a good tune yeah by all means run 12:1 comp but if you want to by easy on it with a decent gain run 10.5:1. on 93 if you run 11:1 you might be pushing into the max of 93 octaine. Those are my thoughts the build list is pretty much basic. good luck.
040 over will prob be as big as i can go thats all the bigger the darton sleves go i havent seen a 040 over piston with any compression, only ones i see sold are stock or 020 over
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
