i was wondering what the highest compression ratio pistons i could run on a stock ecu. spun the #3 bearing on my ld9 and i plan on rebuilding it this winter. but im not really sure what to do. who all reprograms ecu's if it needs to be done. and roughly what is the price?
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The stock ecu can't read compression ratios. On a daily driver i wouldnt go hight then 10-10.5 to one. I personally will be using 10.5:1 pistons on my ohv. You won't have to get anything re-programed but to help tune your motor I would sugest getting an afc to help trim your fuel curve esp. if you add cams as well.
I'm learning more about all this my self and I am sure many others will post as well. NJHK should post shortly as it seems that he is always on late, or Spdibee
Well...that's kind of a hard question to answer.
I'm guessing this is a daily driver so you don't want to go too high. Remember, the higher compression you're running, the higher octane gas you would need to actually run properly. If you go too high, your computer might throw misfire codes etc etc.
I would say...maybe 10.5:1 or 11:1 compression (maybe).
There really isn't any place right now that will allow you to reprogram your ECU. Your only options are piggy back systems (not sure if they will help) or a stand-alone system.
Maybe someone can correct me if I am wrong.
Contact Karo at Car Customs for the pistons...they have to be custom made.
www.kronosperformance.com / 732-742-8837
Juice pushrods wrote:NJHK should post shortly as it seems that he is always on late
That's cause I'm usually bored at work lol
www.kronosperformance.com / 732-742-8837
hey just to let you know a new computer comes blank and needs programing so more than likely you can have it programed for you and modified. Give it a looking into.
George Lopez wrote:hey just to let you know a new computer comes blank and needs programing so more than likely you can have it programed for you and modified. Give it a looking into.
Not really. JBP claims to be able to modify ECU's, but its $500 and you have to send it to them in Canada each time you want something changed. GM dealers and service centers cannot modify the programming (other than little things like turning the DRL's on/off, etc).
4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!
As far as the fuel octane required to accommodate higher compression pistons goes, for a 10.5:1 setup, would the usual 92 / 93 octane pump gas be sufficient?
NJHK (Sexual Chocolate) wrote:Juice pushrods wrote:NJHK should post shortly as it seems that he is always on late
That's cause I'm usually bored at work lol
I know the feeling man i get board all the time when we slow down at night.
And you should be fine on 92. I run 92 mainly b/c i dont know when i will be on the bottle but with my build motor i will run the premo to play it safe.
The ecotec has a 10:1 compression ratio already, and its able to run on 87 just fine. Just that tells you that you could run at least a full point more on street gasoline without any other changes.
I would bet that a 11.5:1 eco would be fine on 92-93 octane with the combustion chambers polished, cc'ed and a good cold air set up. But the problem is, the computer. GM wrote their algorithms and look up tables with 10:1 in mind, so it would probably throw codes, run terrible, or not at all.
With a stock ECM, I would run 10.5:1 but hell, buy a megasquirt , get some squishy pistons and call it a day
1988 Pontiac Fiero, engine transplant underway.
2004 ECOtec, built and boosted
If you are going with higher compression, you might as well do something beneficial like 11.5:1 and run a standalone like Megasquirt
I was a retard, and now I'm permanently banned.
