Head Swap - First Impressions

Well, the head swap has been completed for a week or so now. I have replaced my machine shop stage 1 (whatever that is) ported head with 88 tbi cam, back cut and 3 angle valves. I replaced it with a head ported by mpgmike. The valves where back cut and 3 angle as well. It was shaved to give a CC of 46 to bring the compression up to 8.6 :1. Two Singh grooves per combustion chamber where done as well as grooves in the intake runner Mike calls Power Lynz. I also cryoed the head as well.

I have not yet made it to the dyno. I messed up the valve seals and I am waiting to put on some positive seal ones.

I have noticed that I am blowing IC hoses for some reason. The last time the hose blew off I realized the non-turbo power was way improved. It use to be a complete dog with out the turbo climbing some hills, but now there is no problem what so ever.

The biggest thing is the EGT temps. I have seen a low of 625F at idle with most of the time idle at 700F. Around town I see a low of 775F to 850F. Highway I see 875F to 950F up big hills. Boosting, is a little iffy. The temp drops so quick that by time I see the gauge I see the needle is dropping. The most I have seen is just over 1000F at 12psi being on it for what seemed like a while.

Another thing I noticed is my part throttle knock retard now behaves differently. I can still get knock, but it is much harder to do so. At the moment, I really do not want to make to many comments about that as I am burning oil via my valve seals which will have an effect.

I am pretty sure (though not degreed to be 100%) that my cam timing is close to stockish now. The vacuum is now up from 15 to 17ish. May still be a little retarded from the head milling. Timing was at 12 degrees but I have since lowered it to 10 and will try lower yet. The idea being is that the info on Singh's site and other forums, the grooves are suppose to speed up the combustion process. If that is correct, then people suggest (Mike and others on the turbobuick forum) that more power will be gained by RETARDing the iginition timing. I will probably play with that on the dyno to see what shows up.

I have noticed I can shift into 5th much earlier like around 50km/hr without any problem and still be able accelerate with out any lugging. I can do 40km/hr, but would not in daily driving. Average mileage so far looks to be similiar, but I have been on the gas way more than normal and doing more highspeed highway miles. Though there are parts of my driving where the navigator mileage is up for sure over before.

Can't wait till you get closer to a definative comparison. I'm still wondering about the stock turbo piston design with this modification and have a thought. .. maybe Mike can weigh in.

As I understand this, the lines sole purpose is to initiate turbulance in the CC correct? If so, obviously then the dished pistons will cause a diminished return from the modification's optimal clearance of quench to flat piston surface.

My thought was that intead of a groove cut from the quench area to the center of the CC that perhaps a series of angled holes drilled from the quench area, at an angle, into the CC would produce a greater effect. Basically using the small quench area as designed but the holes to channel the air more directly without piston design being an issue.

I was thinking the same thing about the dished pistons. I was thinking of a custom piston that is flat the same spot our heads are.

Check out the Main site
http://somender-singh.com

Volvo 10 grooves
http://somender-singh.com/content/view/105/52/

Burn pattern
http://somender-singh.com/content/view/106/49/

Other Forums I have found that talk / work with the grooves. Search is your friend.
http://forums.turbobricks.com
http://speedtalk.com/forum

I've read a bit about this on the buick and volvo forums before. I'll check out speedtalk though. Be interesting to see if the design can be tweaked to use the stock piston tops though. A piston redesign doesn't seem like a cost effective direction, in keeping with the spirit of the modification, especially if it potentially brings a new set of issues along with it. I think if I was to give this a go I'd try the holes first with the stock slugs.

Keep us updated on how your plugs look at those temps.

Fixing the quench area by matching the piston and the combustion chamber is a proven and excelent idea. The grooves are not they are all cracked up to be. I have yet to see it be proven on cars with significant pressure like turbo cars. The results are nominal and most gas mpg increase is due to the subconcious and giving yourself better gas mileage. Almost everyone can gain 20% better gas mileage just by thinking about it and forcing themselves to drive differently and smartly.

Areo effects that he bosts and dipects in the picture is not possible during combustion... the pressure is so intense before ignition that it is almost as tight/dense as a solid and doesnt flow, but squeezes into the combustion chamber... hence why quench is good. The fluid at that high of pressure acts more like a gel, and doesnt burn in the depiction he listed... it consumes the unburn air in a nice expanding matter from the point of the spark.

Of course there are even more effects to it, but that is later.


Frank

This is always a good topic, :thumb:

At those temps would the plugs be getting fouled up normally? They are cryoed and what I understand from that, is deposits do not stick as well to the plugs then. So what we see may be effected by the grooves, the cryoing and or both. I have not yet checked them.

Wow. I fluked off an excellent idea! :D

Frank, why do you think the grooves are not what they are cracked up to be? Is that just from a mileage point of view? I understand your gas mileage statement and reconize that. I have tracked my mileage every tank for years.

If the grooves allow us to run higher boost with out detonation, I would see that as a good thing. In my case I went for a little higher C/R. The boost will come. Hopefully, with out a head shim.

Quote:

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Originally Posted by Frank

Fixing the quench area by matching the piston and the combustion chamber is a proven and excelent idea.
Frank

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Has anyone done this to your knowledge Frank? Would a maker like Wiesco be game ... or does this require a ton of R$D?

Quote:

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Originally Posted by puppet

As I understand this, the lines sole purpose is to initiate turbulance in the CC correct? If so, obviously then the dished pistons will cause a diminished return from the modification's optimal clearance of quench to flat piston surface.

My thought was that intead of a groove cut from the quench area to the center of the CC that perhaps a series of angled holes drilled from the quench area, at an angle, into the CC would produce a greater effect. Basically using the small quench area as designed but the holes to channel the air more directly without piston design being an issue.

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I have a junk head on the bench that I tried that very idea on. As I look at it, I can't help thinking CRACKS. I like your thinking as far as the effect the holes would have in the combustion chamber, but I don't think these heads would hold up to the thin areas created by the drilling.

Mike

Your probably right Mike.

Puppet, I pulled all the plugs last night and had a look. Not being a good plug reader, I looked up a bunch of pics on the web. Near as I can tell they look good. The electrode is a light greyish, porcelein is kind of tanish, the first threads are a little black sooty. Probably from being a little rich when I shut it off perhaps.

Maybe change up to a hotter plug now? ... although your description sounds good.

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

thanks for the URL. Best pics by far that I have seen online so far.

My head build is finished, short of putting on the intake manifold and doing a final torquing of the manifold fasteners....some please convince me with dyno data why I should cut grooves in my ported G-head....

The EGT's quoted seem really low, so low catalytic converter performance is probably compromised. Where is the probe located?

What cam are you running with this head?

Another friend who runs a grooved 782 head has slightly higher numbers. His idle #s are close to mine, but his cruise and boosting EGTs are higher. Overall, he saw an ~200F drop in before temps. His tuning has been raising the temps up to more reconizable levels.

My probe is in #4 between 1" and 2" from the head. I do have a #4 coolant mod. I am running an 88 turbo cam, which from my sources, has the same specs as the 88 TBI. Luckly, no cat here to get messed up.

Dyno data is out there. Check Singh's site I linked in up above. The speedtalk forum has some dyno info too. They comparing the best of the before to the worst of the after between 5-10whp more from what I remember. Automotivebreath on the speedtalk forum is the guy to talk to. Over 30 years doing engines, Doing the grooves since Jan of 05 with the help of Mr. Singh and over 20 engines so far. He is big into the 1/4 but big iron stuff.