b20a1 little power in high rpm

[davke]

so, after first testride, i noticed that the engine doesn't wont run well at 6k and more rpm and there is no power too :dunno: . on little rpm everything seems to be ok. so what can be? thank u for answering. it seems the engine doesn't get fuel or something.. but the ecu is from b20a1..

[shepherd79]

do you have 3 geez accord or 3G prelude?

Early JDM B20A motors were designed for low torque and mid power range. if i remember correctly, the power will drop after 5500rpm. In reality, you may want to do regular tune up and change the fuel filters, but it won't pull any harder past 5500 or even 6K RPM.

[voiceinurhead05]

If you're having trouble getting to the top end it could be a valvetrain issue. I'm not familiar with early b-series motors, so I'm not exactly sure how they perform. If you reaaaaach the top end with no problems, and find a lack of power, that just means that your engine doesn't have much top end power. There are some things you can do to your engine to make more top end power. Forced induction is one way, particularly turbocharging. High compression pistons may help, as well as a ported and polished head. As for fuel delivery... is it dual point FI, or multi point?

[voiceinurhead05]

If you're having trouble getting to the top end it could be a valvetrain issue. I'm not familiar with early b-series motors, so I'm not exactly sure how they perform. If you reaaaaach the top end with no problems, and find a lack of power, that just means that your engine doesn't have much top end power. There are some things you can do to your engine to make more top end power. Forced induction is one way, particularly turbocharging. High compression pistons may help, as well as a ported and polished head. As for fuel delivery... is it dual point FI, or multi point?

[carotman]

Well ,the intake manifold design will not make much power above 6000 rpm. You might want to upgrade to a later B series intake manifold. I an running an Edelbrock manifold and I don't ahve any problems to rev it to the 7200 rpm cutoff limit from the PK2 ecu :D

[davke]

its 86' the 2gen lude engine (gold valve cover). i put it into my 3g accord. i changed injectors from my old a20a4. i heard they are the same. what about fuel pump? by the way valvetrain setting is good. i need that the biggest power of the engine 137hp would be on 6k rpm, but it seems on 5k or 5,5k rpm, like on my a20a4... i dont want to change something like manifold, i need a stock complectation..

[Bglad420]

Sounds like you need a drink...I'll drink it for you , delicious!!!:)

[davke]

im drunk allready now :)

[carotman]

Wel, the stock Redline is set at 6500 rpm so the peak power is supposed to be arouns 6000 rpm. Anything above that will give you less power on a stock engine. You might want to replace the stock air intake system with a short ram or a CAI.

[A20A1]

Get a header :)

[thegreatdane]

The stock redline for the B20A1 is around 7000rpm and it produces peak power up to around 6500rpm. So definately sounds as if somethings wrong.

What is your ignition set to? And why did you swap out the injectors, were they bad? Did you block off the air valve if you're not using it or did you connect it?

[davke]

then i turn off an injector then other, the rpm drops were different, so i changed them from my old a20a4. i don' know how to tell what my ignition setting is ;]. yes, i did'nt block off the air valve, i just connected it to the black box, thats all. i guess it is not working, i saw your post in my other thread. i put the black box from prelude too, but i guess i need to make one wire from ecu to the solenoid?
and for what purpose that air valve is sitting there? for more air?

[thegreatdane]

According to the shop manual, the air valve opens upon deceleration to avoid negative pressure/vacuum in the manifold. So unless you have it somehow completely wrong connected that shouldn't affect your engines performance. And yes you need to wire it to the ecu to make it work.
You have to use a timing gun pointed to the flywheel to read and set the timing, but if you havent touched the distributors timing setting since the last time the engine was running good it's probably where it should be.

Check your spark plugs, wires, cap and rotor and check that your grounding wire connections from the engine to the chassis are all good.

[davke]

okay, thank you, i will try to set the ignition and to check the fuel pressure tomorrow. but i have one more question for you: where i can find info about valves adjusting, what side should i set on my b20a1? on a20 the intakes should be around 0.005-0.007 (a good number to set it to is 0.006) and the exhaust side should be around 0.010-0.012. what about b20?

[thegreatdane]

The specs are a bit tighter for the B20A1 than the A20A4.

B20A1
Intake: 0.08mm-0.12mm
Exhaust:0.16mm-0.20mm

A20A4
Intake:0.12mm-0.17mm
Exhaust:0.25mm-0.30mm

Everything has to be done with a cold engine.

[davke]

thank you thegreatdane, you are nice guy :) and i like your accord very much, good looking