Project Honda Civic- Fixing a Leaky Head for more Power!

Project EJ Honda Civic- Fixing a Leaky Head for more Power!

By Mike Kojima

We were planning to methodically add parts to our project Civic’s B18C engine one bit at a time to see how they affected power and powerband.  Unfortunately, our car had other ideas.  Although Annie had driven the Civic for over 200,000 miles on a daily basis with not a single hitch, a trip to the track exposed the car's age.

 Read more about Project Civic here! 

 Project Honda Civic- Fixing a Leaky Head for more Power!

Tom Fujita of Portflow Design uses a Serdi valve machine to crank out good performing heads.  The Serdi makes doing a high quality valve job pretty fast and accurate.  Tom is leveling our head in the machine.  The Serdi has a floating head that moves on air so it can be accurately and quickly positioned over each hole.

 Project Honda Civic- Fixing a Leaky Head for more Power!

A bubble level on an old valve helps Tom set up the head perfectly level.

 Project Honda Civic- Fixing a Leaky Head for more Power!

As a first step, Tom cuts the exhaust valve guides shorter.  On the B Series head the guide blocks a lot of the port area.  15 CFM can be gained by cutting it down.  Tom conservatively cuts it flush on the Serdi with this cutter.  This makes the exhaust valve guide the same length as the intake so it is not unreasonable and still gives the valve plenty of side support.  This cutter uses an old valvestem as a guide and faces off the unwanted valve guide that protrudes into the port.

 Project Honda Civic- Fixing a Leaky Head for more Power!
 Here is the cutter about to be put into the exhaust guide.
 Project Honda Civic- Fixing a Leaky Head for more Power!
The dial indicator is used so Tom can consistently cut the guides to the same length.

When at Buttonwillow, her car started to overheat and even though she stopped right away, the head gasket was blown.  When the head was pulled to fix the gasket, we noted that the head’s deck was warped 0.0005-0.005”. 

Project Honda Civic- Fixing a Leaky Head for more Power!
A cut vs uncut exhaust valve guide.  The cut on is on the left.

Since we had to machine the head’s deck, we decided to have Tom Fujita of Portflow design clean the head up at the same time with a mild port job and a good performance valve job.  This low cost bit of head work can be turned around by Portflow quickly and economically. 

Read more about Project Civic here!

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Wednesday, June 22, 2011 3:01 AM
A hand-ported head is a beautiful thing. They may not beat CNC'd heads in outright performance, but seeing old masters like Tom working their magic is a treat. In terms of bang for buck, it's hard to do better.
Wednesday, June 22, 2011 3:56 AM
Any reason that only the exhaust valve guides were cut down?
Mike Kojima
Mike Kojimalink
Wednesday, June 22, 2011 4:58 AM
Read the third caption again.
Mike Kojima
Mike Kojimalink
Wednesday, June 22, 2011 5:01 AM
This is not full porting but Portflows radius valve job with some clean up blending. This is a bang for the buck mod that gets good gains for a moderate price. There is also quick turnaround for this. This will get over half of the gains you might see in a fully ported head and all you need for a mild street going B series.
Wednesday, June 22, 2011 5:36 AM
Thanks for the post! I've always wondered on a more moderate job like this, is it to be expected that low end power will be lost, or is this almost all positive gains throughout the powerband?
Wednesday, June 22, 2011 7:12 AM
Some wonderful work here and I learned something about porting heads.
Nice work.
Wednesday, June 22, 2011 7:51 AM
Big fan of Tom's work.
Wednesday, June 22, 2011 9:27 AM
What causes a blown head gasket?
Mike Kojima
Mike Kojimalink
Wednesday, June 22, 2011 10:18 AM
Porting like this will not cause a loss of bottom end power, it will create gains across the board.
Der Bruce
Der Brucelink
Wednesday, June 22, 2011 11:01 AM
Mike - just like a good editor and writer! I'm reading early on and thinking this is a lot of work for some 150hp run around town/ occasional track car AND THEN you drop the 200hp number leaving us wanting more :) I'm assuming you guys are going all motor, but did you ever think about going supercharged?

What's the expected RPM max with the current port and refresh?

Jasonrg77 - That's a big question but just three quick things off the top of my head 1) Unregulated cylinder pressures (seen often with boosted motors) 2) Slight head warpage over time (because head studs don't usually get retorqued by most of us) 3) Material degradation over the motors lifetime. I'm sure there are a plethora more reasons but reasons 2&3 are why you read about so many guys getting ARP head studs and often times metal head gaskets, etc, especially on boosted motors
Mike Kojima
Mike Kojimalink
Wednesday, June 22, 2011 11:14 AM
Probably something like 8500 rpm.
Der Bruce
Der Brucelink
Wednesday, June 22, 2011 3:36 PM
You'll probably cap it @ 7500 but I say let it sing!
Wednesday, June 22, 2011 10:02 PM
A good B18C engine (fully built N/A) can make 270hp reliably. Nice work and attention to details.
Thanks for sharing.
Thursday, June 23, 2011 4:23 AM
@ Bruce: B18C1 engines rev to 8100 in stock trim and B18C5s (Integra type R) to 8400 rpm. So ~8500 rpm with a mildly built engine like Mike mentions should be just right.
Thursday, June 23, 2011 8:44 AM
Definitely Sending my cylinder head to Portflow!

I can't wait to see what kind of Skunk2 camshafts will be going in!
Thursday, June 23, 2011 11:32 PM
Cool post Mike. That valve unshrouding looks awesome. I'm wondering if it was significant enough to affect the compression ratio. Did you guys do a pre and post CC on the chambers? I'm guessing you could probably counter the effect with pistons, but I'm sure higher compression pistons were in the plans any way!
Mike Kojima
Mike Kojimalink
Friday, June 24, 2011 7:06 AM
With the surfacing, it about breaks even.
Saturday, June 25, 2011 5:45 AM
I have a question regarding the headwork.

Would the combustion chamber flow characteristics improve if the squish area was to be removed?
Mike Kojima
Mike Kojimalink
Saturday, June 25, 2011 12:42 PM
No and removing squish is bad, bad, bad.
Monday, June 27, 2011 2:27 AM
Another great read, Mike, thanks. These pics are a sight for sore eyes :-)
Tuesday, June 28, 2011 11:43 AM
Portflow = great head!!!
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