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91 Hatch
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Discussion Starter #1
I recently finished my dohc zc built with cp pistons, eagle rods, acl bearings, and supertech valve springs and retainers. My question now is: Would I be able to use my stock ECU for my built? Would it cause any damage?
 

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Certified O.G.
A Shitbox
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Are you gonna be boosting? or NA?
 

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91 Hatch
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Discussion Starter #3 (Edited)
sorry.. yea iam going to boost...jus wating on the rest of the parts for my turbo kit...the resone why i ask because i really need a car for work????so do u think ill be alright with stock ecu???
 

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nonvtak ftw
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5,230 Posts
Why is this even a question anymore.
No it wont be good. Protect your parts and investment, chip the ecu and get a tune.

I would walk to the bus stop before i tried to move my car 20ft on a stock ecu. And mine was made to actually see boost.
 

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91 Hatch
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Discussion Starter #6
Why wouldn't it run good? What would be the symptoms from running the stock ECU?
 

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The only part on your list that effects anything is your pistons.

Compare your current compression ratio to the stock one.

your stock ratio is what, 9.5? 9.6?

your ecu will run it just fine if you are running between 8.9 and 10:1 compression, given that 9.5/9.6 is accurate

anything more or less, dont drive
 

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()*#$(*$
93 Legend L Coupe.
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11,404 Posts
Pfft. Wrong.

Changing the pistons in the DOHC to anything other than similar high come pistons comepletely changes the timing requirements of the engine. Most pistons will drop the CR down into the low 8s or even 7s. This effects the DOHC much more intensely than the SOHC because of the huge chamber. This limits the dynamic compression, which helps mix fuel and will lead to running rich enough to not allow the engine to break in properly.

A stock ECU will, in fact, run the engine poorly. It will start. It will drive. However, I will say with 95% certainty that you will not get a good break in if you don't tune the engine, at the very least the fuel, before doing your initial break-in.

Find out and see for yourself. The stock ECU isn't even tuned well (for performance standards) for STOCK engines.
 

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91 Hatch
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Discussion Starter #9
my compression for the cp piston when i bought them were 10.0???but i heard compression drops in the dohc zc from 10.0 to 9.0??? what kind of damage will it do to my motor with stock ecu???just asking because i had the motor running for about 2days now on stock ecu????i would appreciate the help
 

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more gas=less oil kept on the cylinder walls

Probably would increase thermal expansion from reduced lubrication.

I didnt realize the stock ecu effected it so much, but from research honda shit, beavers comments hit home way more often then not
 

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91 Hatch
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Discussion Starter #11
ok do u think that my motor will be ok since i was driving it for like dayd with stock ecu??
 

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()*#$(*$
93 Legend L Coupe.
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Any SOHC turbo piston in a DOHC D will drop the compression ratio much lower than you think.

Stop driving your car. At the very least get a wideband oxygen sensor setup and report back what the air fuel ratio is at idle.

Repeating for clarity:

Stop driving your car. You know NOTHING about what is going on inside of it. You don't have the experience or the research to have a clue. STOP!

If it doesn't sound terrible, it is most likely OK, but you are plowing into the "ignorance is a broken engine" territory. Get more info. Do not pass go. Do not collect $200. STOP.

The reasons why I am saying this:
A. You have no idea what effects the compression ratio.
B. You haven't even attempted to listen to anyone in this thread who has either turbo'd their engine or built an engine.
C. You don't listen.
D. You aren't listening.
E. You aren't comprehending what we are trying to tell you in order to make your life less miserable. Think abut what happens if you blow the engine. Really. Think about that. Then think about how many people tried to get you to just STOP and take a few minutes tolearn why you should NOT drive the car without knowing WTF is up with it.
 

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91 Hatch
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Discussion Starter #15
chill out man!!if u would talk to me like that in person i would beat your beaver ass...first of all i contacted king motor sports and told me that ill run fine with stock ecu till engine brake in!!!thanks for nothing!!!dick head
 

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91 Hatch
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Discussion Starter #16
i hate rude people like that!!!!iam new at this building shit so calm down lilttle man!!
 

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chill out man!!if u would talk to me like that in person i would beat your beaver ass...first of all i contacted king motor sports and told me that ill run fine with stock ecu till engine brake in!!!thanks for nothing!!!dick head
i hate rude people like that!!!!iam new at this building shit so calm down lilttle man!!

Take your own fucking advice and calm down.

He told you earlier his advice was to NOT run it.

He gave you valid reasons

If you cant accept them, fine, do your thing.

But at least remember he tried to help you.

He obviously doesnt beat around the bush. he got right to the point and let you in on the whole thing from his point of view

chill out and have a beer or something, maybe puff
 

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1988 Honda CRX
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You don't have a clue yet you abuse those that do.

Good luck getting more help.
 

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Friend of the D
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Another Dick head...lay off beavers dick..u fag
You don't have a clue yet you abuse those that do.
There are a couple of sources of advice on D-series. You can get a lot of it from a noobs who really know nothing themselves. Then there are those members who actually know something and take the time to share that information with people. The Beaver is one of those guys. You asked for his knowledge and he shared it with you. If you don't like his advice and choose not to take it, that's fine, but don't bitch because it's not what you wanted to hear! Go ask another noob and good luck with your build!
 
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