So I want to put this fantastic all motor B20 in my Del Sol.
It seems to have compression around 12:1 or so. I must use hi test gas or get detonation.

Relevant Motor Specs:
Block- B20B
B20Z pistons
GSR head
Head shaved .05 mm

Yes, it's a great motor, but I want to run regular gas.
So how do I lower compression to accomplish this?
Pistons?
Head swap?
spacer at head gasket?
Could it be retuned and not change any parts?


I know, I will lose HP, and that will be OK

 

You don't have 93 octane in florida?

 

Yes, we do.
I just don't want to pay for it.
I want engine longevity and power, but can get by with less hp.

All I really want is more torque than a stock 1.6 motor.
A 25% increase in cc's to 2.0 liter will do that for me and should be satisfactory with regular gas.

 

Well if you just want more torque swap your b20v for a non vtec motor and cash. You cant go below 93 octane at 12:1 compression.

 

Well, I already have this motor.
It has everything first class, and it has just 3,000 miles on it..
I would rather modify it than get another motor and take my chances.
I hope to never take it out again.

 

I don't know why premium gas is a big deal...our cars only hold 10-12 gallons. You're spending $3-5 TOPS per tank of gas over regular. Is it worth the time/money/hassle of swapping a bunch of **** around?
Probably not.

If this was a 30 gallon tank then I could see your gripe...this just make me SMH

 

I am old Chevy street racer and know well the characteristics of a 350 Chevy with 12.5:1 pistons. My driving is pretty tame compared to the old days, and believe that I would prefer a lower compression engine. I can pay the gas price if the engine NEVER knocks.

Would a Honda engine with fuel injection and electronic controls make my fears groundless?

 

MANY guys, including myself run 12:1-12.5:1 compression on pump gas with no problems. What dictates how long it will last is the tune that is put on the motor. Has the motor been professionally tuned w/ A/F ratios and the works? If not, get that done and you should be just fine. Heck some guys even push 13:1 on pump, just takes some timing adjustments with fuel mapping done correctly.

There are "band-aid" fixes to lower static compression like running a thicker HG which is an option, but with this motor I personally do not feel it is needed to be safely driven/tuned on pump gas.

 

B20Z pistons and a GSR head is NOT 12:1 compression. More like 10.5:1.

You should be able to use 87 in it, but pull a couple of degrees of timing and maybe up the fuel pressure 1-2 psi, if you can.

 

Agreed. I overlooked the pistons. You are well within safe parameters on pump.

 

Ejv8s10 check your in box

 

sooo....what are you using for ecu/tuning?
i dont think theres a flat out oem ecu that will really run that motor perfectly.

if its a vtec ecu did you tap the block somewhere for the knock sensor and run it?

 

I run 12.5:1 on 91 octane

 

The wrecked 95 Civic that the engine and trans are in is now mine. I know the guy that built it. He is not currently available to answer those questions. He put over $8,000 into the engine and trans, doing it right and not cutting any corners. There was a custom ECU and dyno tuning. I saw the engine being built, and that head is a thing of beauty. I rode in the car and was impressed.

Now? the car is wrecked (rear end) and can't be driven. I need to pick it up in Miami before I can answer any details.

Anyway, I want to use that engine, not trade it as someone suggested. I really would like to have it in my daily driver if the compression does not cause problems. I want it to last a long time.

If the compression is actually 10.5:1 as someone suggested, that will be great. How much will that head shave (.05 mm) affect the compression? I don't know if that is significant.

 

That little of a head shave will have almost no change in compression. Maybe 2 tenths max