Workin My G Head

[Juggy]

I have a crappy S60 big valve G head here......so I finally decided to do something with it....I sent it to a machine shop to have them install the BIG valves (44mm and 36.8mm????) into my stock G head....

so I have a couple questions here...

are the S60 big valves backcut?? if not what degrees should I have them cut too....

also since the G head has lower compression, is it best to bring back the compression up to swirl head?? if so, what should I have them get it CC'd too...

ive always used the MP headgaskets....heard they are .030" bigger?? should I get the head milled for that too??

The head is going to get a mild clean up, and he is gonna flow bench it for me afterwards, and compare it to the S60 flow #s...

does anyone have the flow #s for a stock G head, and a S60 big valve head? just to make sure im not gettin BS'd here if he cant supply me with the bench #s for the S60 head

thanx,
Cory

[cordes]

If you are going all out, I like the G-head on a 2.2 or a 2.5. Others say swirl for a 2.2 and G for the 2.5. I would not bump the compression up at all.

[Juggy]

If you are going all out, I like the G-head on a 2.2 or a 2.5. Others say swirl for a 2.2 and G for the 2.5. I would not bump the compression up at all.


well i know they bumped up compression on the S60 head to bring it to swirl status....

also its a 445 head that im having worked, not the deeper bowl'd 287 head....maybe I should just go with a light mill for the thicker MP gaskets...

it will be going on a 2.2L

[puppet]

Just about all the info you asked about is on Gary's website.

[boost geek]

I run a ported G head on a 2.2 and would never go back to a swirl. With the swirl I was getting detonation at 0 boost and up when I pulled it and switched. Cleaned the piston tops and put on my G head, problem gone.

How can you have a crappy big valve G head? :confused:
If the compression was brought up on a S60 G head, run a copper shim from Felpro. I'm using one and hasnt failed to 20 psi spikes. (with ARP head studs)

[glhs875]

That's the same basic setup Iam running (445 casting - 53cc chambers) for my head. I didn't have my 44mm & 36.8 valves back cut, but it might help I don't know. I highly ported my own head. With the S3 Taft cam - SC6152 Turbo and lots of other crap, mine's a revver! It's pulling pretty darn hard to the rev limit I have set @ 7500rpm, with tons of tuning yet to do!

[jckrieger]

What kind of calibration and EGT's do you guys have who are running G heads with the 2.2L? I had a G head on my 87 CSX with a big turbo and intercooler and couldn't keep the EGT's under control. I tried tuning the car for several weeks and eventually blew up the trans, so it's back to the swirl I go.

[turbovanman²]

I agree, my EGT's are much higher running the G-head. Honestly, the around town lag is killing me, I wouldn't recommend a G-head on a heavy vehicle, :(

[glhs875]

What kind of calibration and EGT's do you guys have who are running G heads with the 2.2L? I had a G head on my 87 CSX with a big turbo and intercooler and couldn't keep the EGT's under control. I tried tuning the car for several weeks and eventually blew up the trans, so it's back to the swirl I go.

You probably need more ignition advance to lower the EGT's. If so that would also help to decrease lag as well. Bumping up the compression to the same as with the swirl combo would help decrease lag also.

[Bubba]

I'm in the process of having a g-head done up for me at FWD performance. It'll have the big intake and exhaust valves, chromoly retainers, better MP springs and for a cam probably the F3 cam. This will be going on my Shadow convertible with a 2.5 motor. I plan to have it flowed just so I know for sure what I've got.

[turbovanman²]

You probably need more ignition advance to lower the EGT's. If so that would also help to decrease lag as well. Bumping up the compression to the same as with the swirl combo would help decrease lag also.

Tried the advance thing, not much change, and with more advance, ping city, :(

[glhs875]

Tried the advance thing, not much change, and with more advance, ping city, :(

Maybe it's too rich? I don't know what your EGT's are running, or alot about your combo, I'm just throwing out some ideas. I don't know what my EGT's are running either, it may scare me if I did know!!! :eek:

[jckrieger]

I tried advancing the timing up to 6 degrees over the 87 CSX Stage 2 cal and it only dropped the EGT's to 1550 at 20psi of boost. Even adding and subtracting 10% fuel at WOT the temps wouldn't decrease. Maybe if I had a WBO2 and a week on the dyno...

[BadAssPerformance]

Or just a WBO2 and some laps around town and a trip to the track ;)

the MP G head on the 2.2L in my Z works pretty well...

[glhs875]

I tried advancing the timing up to 6 degrees over the 87 CSX Stage 2 cal and it only dropped the EGT's to 1550 at 20psi of boost. Even adding and subtracting 10% fuel at WOT the temps wouldn't decrease. Maybe if I had a WBO2 and a week on the dyno...


What's wrong with 1550? That's about where Kevin Davis runs his 16V engine. Sometimes even a little higher. His engine has been holding up just fine up to 30psi. I've heard of someone that has a 10 second 8v from a good source that he runs the EGT's in the 1600 & 1700+ area.

[turbovanman²]

What's wrong with 1550? That's about where Kevin Davis runs his 16V engine. Sometimes even a little higher. His engine has been holding up just fine up to 30psi. I've heard of someone that has a 10 second 8v from a good source that he runs the EGT's in the 1600 & 1700+ area.

I am around 1600 aprox 1/2 way down the track. Pistons can take it, just worried about the head gasket firing ring getting hot and BAM.

[Frank]

Pistons this, headgaskets that.... nobody looks at the valves... there is no reason to be higher then 1400 going down the track.


Frank

[Bubba]

My EGTs go past 1600 degrees constantly due to a few variables, higher compression and inferior e-bay egt probe mainly I believe.

[glhs875]

Pistons this, headgaskets that.... nobody looks at the valves... there is no reason to be higher then 1400 going down the track.


Frank

What can be done to lower EGT's if there still a little high after a combo is tuned the best that is known it can be? Raise the octane, which higher octane should burn cooler? Maybe up exhaust flow to let more heat out? What else etc.? I'd say that a certain amount of overlap on the cam is needed for this purpose.

[turbovanman²]

Pistons this, headgaskets that.... nobody looks at the valves... there is no reason to be higher then 1400 going down the track.


Frank

Stainless valves and even running at that temp or higher, there still good. How do I know, when I swapped out the Swirl head, they didn't have a mark on them, :nod:

[glhs875]

Stainless valves and even running at that temp or higher, there still good. How do I know, when I swapped out the Swirl head, they didn't have a mark on them, :nod:


I agree, stainless valves will take alot of heat. The head I have on my car now was on another engine I had back in the 80's, that I got things so hot that the pistons melted (way too lean) and even some of the combustion chambers were slightly damaged. The valves were perfect!!!! I'm still using the same valves and head that have only been lapped in when I freshened up the head for the engine I'm using now. Never even had a regrind on the valves.

[t3rse]

i'm running pretty damn rich (10.7, don't worry, i'm leaning it slowly) on a g with 3 angle back cut big valves at 1400 egts, makes 22.3 psi around 3.5k, 1500 egts are fine...1600 i'd start getting scared...esp w/o stainless valves...btw, anyone who says to run 11.1:1 af on the street can suck my balls: i hope you like re-ringing your motor...got a dsm in the garage with grooves in the walls owned by a fella that listened to this type of advice (gas washing oil off the walls).

[jckrieger]

Don't inject any more fuel than necessary to get reasonable exhaust temps and no spark knock... The GN guys tune for .73V on the narrow band O2.