View Poll Results: How should I home port my heads?
Polish and go!
4
20.00%
use old school tricks to port and tweeak
6
30.00%
It's black magic! Send to a Pro, mang
3
15.00%
Use them as-is! They make all the flow you need now!
7
35.00%
Voters: 20. You may not vote on this poll
How-to L92 home porting?
03-19-2011, 06:28 PM
#1
How-to L92 home porting? I've done some looking around but don't see much on this topic.
I'll have my heads off in a few and figured I could do some touch up. I'm a novice head porter with prior experience on some old Pontiac heads. I was able to improve flow everywhere up to .650 lift on those heads using basic knowledge and careful choices. At peak I improved intake lift by 50cfm
I don't really expect to do anything ambitious but if I have the chance why not do some stuff to make them work a little better?
At the moment I think I'll smooth out the exhaust side. It will be a modest amount of materiel removed and not modify the port shape = keep me out of trouble?
Also, what tools do you guys use on the aluminum heads?
Any help appreciated. PM me if you like, as well.
Current combo
Stock L92 engine
Custom LME cam
1 3/4" long tubes
2.5" exhaust
2900 car
manual 6 speed
Ported TB
cleaned up intake
I'll have my heads off in a few and figured I could do some touch up. I'm a novice head porter with prior experience on some old Pontiac heads. I was able to improve flow everywhere up to .650 lift on those heads using basic knowledge and careful choices. At peak I improved intake lift by 50cfm
I don't really expect to do anything ambitious but if I have the chance why not do some stuff to make them work a little better?
At the moment I think I'll smooth out the exhaust side. It will be a modest amount of materiel removed and not modify the port shape = keep me out of trouble?
Also, what tools do you guys use on the aluminum heads?
Any help appreciated. PM me if you like, as well.
Current combo
Stock L92 engine
Custom LME cam
1 3/4" long tubes
2.5" exhaust
2900 car
manual 6 speed
Ported TB
cleaned up intake
Last edited by Lurk; 06-25-2011 at 09:50 AM.
03-22-2011, 12:18 PM
#2
Teching In
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with a l92 head you can get in troble fast with old school tec a good vj and a blended
boul is all that u should do if this is your first set .do not lay the ssr back at all
boul is all that u should do if this is your first set .do not lay the ssr back at all
03-22-2011, 06:57 PM
#4
Porting I am like you and like to touch everything in my motor.G.M spent big money to get those ports right.A bowl blend and good valve job is more than you need.Good luck with your project!
03-24-2011, 07:37 PM
#6
Launching!
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mmmmm... If it were me, I would not enlarge the CSA. I would remove the bosses for the valvecover and the rocker bolt. I would also narrow the valve guide boss and just blend the bowl. After that send it out to get a nice serdi valve job with nicer springs and hollow valves.
03-25-2011, 05:17 AM
#7
Launching!
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the bulk of the gains would be from working the bowl, SSR and of course the VJ.don't worry about the rocker bolt boss or trimming the valve guide.
honestly if your a novice i wouldn't touch the SSR.
honestly if your a novice i wouldn't touch the SSR.
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04-07-2011, 12:10 AM
#9
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These heads are gonna respond to a good bowl job. Don't open the intake runner unless you have a bigger than stock intake. The exhaust can be gasket matched and smoothed but other than a valve job , new springs , and lightweight valve I wouldn't waste my time
06-25-2011, 09:07 AM
#10
Results Thanks again to all you guys that commented, it helped to hear it all.
I managed to complete my heads. Worked with LME here in Houston and now have some results.
Took the heads in and got a performance valve job.
Intake side
LME was kind enough to plunge cut the intake bowl.
I blended the valve job on the intake side. Then working from the other end I kept the grinder moving and removed just enough material in the ports to lose most of the cast parting lines. I didn't touch the floor of the intake port at all. Then I thinned the valve guides extensively. Everywhere else I did minor touch up to blend transitions from the cuts. Lastly I removed virtually all of the spring pocket bulge and all of the valve cover bolt bulge.
Final throat diameter was about 1.94"
up from 1.88"
Exhaust side
I was told to blend the throat all the way up to the seat of the valve job. That was a lot of grinding!
After the valve job the throat was 1.40" up from 1.36"
I didn't measure after my blending, but just imagine that all material was removed just inside the seat!
Thinned the guide a lot. Polished all the surfaces out until the parting lines were mostly gone. Knowing I was going to be using a minimum of 1.75" headers I measures the port width and subtracted that from 1.75" So - 1.75-1.69 = 0.06"
Divided this by half and scribed the amount all the way around the port exit.
This was the line I blended out to from the exhaust port to the gasket surface. Blended back about 1"
From the outset, I planned to do this quick and dirty... I don't intend to have them on display so I stopped at this effort with no polishing or micro-polishing with a mirror finish. The heads don't look like it either, hahaha. Common sense says it makes no difference if you accept the idea of how the air acts and flows.
Finally I smoothed the spark plug nipple or basically just rounded it off a touch and had the heads cut 0.030" to raise compression. It's my understanding the valve job included a back-cut on the valves too.
Got the heads back last week with a flow sheet. Paid $50 I hope it helps someone beside my curiosity....
LIFT __ 100 200 300 400 450 500 550 600 650 700
Intake _ 71 148 222 275 297 317 332 343 350 323
Exhaust 51 108 152 190 208 217 223 228 231 235
peak cam lift on the custom cam is 0.630 and I will be using the set on a stock L92 shortblock.
I managed to complete my heads. Worked with LME here in Houston and now have some results.
Took the heads in and got a performance valve job.
Intake side
LME was kind enough to plunge cut the intake bowl.
I blended the valve job on the intake side. Then working from the other end I kept the grinder moving and removed just enough material in the ports to lose most of the cast parting lines. I didn't touch the floor of the intake port at all. Then I thinned the valve guides extensively. Everywhere else I did minor touch up to blend transitions from the cuts. Lastly I removed virtually all of the spring pocket bulge and all of the valve cover bolt bulge.
Final throat diameter was about 1.94"
up from 1.88"
Exhaust side
I was told to blend the throat all the way up to the seat of the valve job. That was a lot of grinding!
After the valve job the throat was 1.40" up from 1.36"
I didn't measure after my blending, but just imagine that all material was removed just inside the seat!
Thinned the guide a lot. Polished all the surfaces out until the parting lines were mostly gone. Knowing I was going to be using a minimum of 1.75" headers I measures the port width and subtracted that from 1.75" So - 1.75-1.69 = 0.06"
Divided this by half and scribed the amount all the way around the port exit.
This was the line I blended out to from the exhaust port to the gasket surface. Blended back about 1"
From the outset, I planned to do this quick and dirty... I don't intend to have them on display so I stopped at this effort with no polishing or micro-polishing with a mirror finish. The heads don't look like it either, hahaha. Common sense says it makes no difference if you accept the idea of how the air acts and flows.
Finally I smoothed the spark plug nipple or basically just rounded it off a touch and had the heads cut 0.030" to raise compression. It's my understanding the valve job included a back-cut on the valves too.
Got the heads back last week with a flow sheet. Paid $50 I hope it helps someone beside my curiosity....
LIFT __ 100 200 300 400 450 500 550 600 650 700
Intake _ 71 148 222 275 297 317 332 343 350 323
Exhaust 51 108 152 190 208 217 223 228 231 235
peak cam lift on the custom cam is 0.630 and I will be using the set on a stock L92 shortblock.
06-25-2011, 09:45 AM
#12
more pics Intake
WD40 was the magic lube to keep the burrs empty. Worked perfectly.
Used the same tools to polish the intake manifold. The blue abrasive ball thing worked OK on the composite material. I didn't try it on the heads obviously.
WD40 was the magic lube to keep the burrs empty. Worked perfectly.
Used the same tools to polish the intake manifold. The blue abrasive ball thing worked OK on the composite material. I didn't try it on the heads obviously.
06-26-2011, 11:53 AM
#16
08-13-2011, 01:25 PM
#19
Launching!
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Some of the most important things head porters do have nothing to do with the ports, like back cuts on the valves tulip shaped exhaust valves and making sure your bowl area does not exceed 85% the diameter of the valve. A bowl too large will have the same effect as a bowl too small. Porting is not just making the ports bigger, its directing the airflow around the valve and you almost never wanna lower the floor of a port except in the short side area just above the valve bowl.
08-13-2011, 01:46 PM
#20
I've done porting before, my first set was on some VW heads where I learned a bit. I ported my LT1 heads and got 255/190 @ 600. Car put down 390/367. I bought some 241s to port for my Ls1 rebuild for the SS. I plan to port them and put some 2.02s at least in them. I'm not looking for killer power just some decent perf.
