93 head port & polish progress pics (56k a little slow)
#22
DINOSAURUS BOOSTUS
Expert Gearhead
Originally Posted by JimmyFloyd
I am very interested in this for my car. I have a complete 93 L67 engine in my garage that I can pull parts from for this if you want to try a second set for me, or when you get this perfected. I will also see if I can get a set of heads and LIM off one in the junk yard to send back with bill. I know where there is a 92, but I think the heads are different (someone correct me before friday morning) I would love to have this done for my car. Got the manifolds in the basement ready to go.
#24
Senior Member
Certified Car Nut
Originally Posted by willwren
92 Heads won't work on any other year.
#25
Junior Member
Posts like a Ricer Type-R
Raising the compression would be BAD considering the effects I'm seeing.
The Zilla is running much better now, but I still have KR. I know I need to re-torque the exhaust, but that can't be all of it.
Greyhare'* theory is that the LIM porting allows 20% better flow into the cylinder (that number is from porting gains that were measured). This is backed up by a slight decrease in boost. I lost from half to a full pound of boost and barely go off-scale at 10.25-10.5 psi now. All that extra air and fuel in the cylinder has to compress. I'm going back to TR6 plugs this weekend, 2 heatranges colder than stock instead of one, and see if that helps. It should.
Because of the increased flow, I MIGHT have to go to a slightly larger pulley. But we'll try the plugs and exhaust retorquing first. I'm still undecided as to plug gap on the TR6 plugs. I don't want to go all the way to .045 initially, so I'll probably go .050".
The Zilla is running much better now, but I still have KR. I know I need to re-torque the exhaust, but that can't be all of it.
Greyhare'* theory is that the LIM porting allows 20% better flow into the cylinder (that number is from porting gains that were measured). This is backed up by a slight decrease in boost. I lost from half to a full pound of boost and barely go off-scale at 10.25-10.5 psi now. All that extra air and fuel in the cylinder has to compress. I'm going back to TR6 plugs this weekend, 2 heatranges colder than stock instead of one, and see if that helps. It should.
Because of the increased flow, I MIGHT have to go to a slightly larger pulley. But we'll try the plugs and exhaust retorquing first. I'm still undecided as to plug gap on the TR6 plugs. I don't want to go all the way to .045 initially, so I'll probably go .050".
#28
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Randman1; I would stop any additional porting on the exhaust side. You have killed the short side radius and and also there is no floor left. Bigger is not always better!!! What makes the power is the port velocity. As we speak, I am spending time on the flow bench while porting a set of Series 1 /1994 cylinder heads. As an example, just look at the following link for an L36 exhaust port that has been maximized.
http://www.gesslerheadporting.com/me...3800-head1.jpg
You may notice the port is not round; round ports are very weak on velocity at the lower lift ranges and only good for high RPM. This was the problem with the old Pontiac Ram Air V and Tunnel Port Heads cylinder heads; the ports flowed big numbers, they were round and you could almost fit a tennis ball in them. However, the did not flow at the lower and mid-lift numbers and they got outrun by the other makes. A port needs to build energy at the lower and mid-lift numbers to make power.
Take a look at a set of Ram Air V and Tunnel Port heads:
http://img55.echo.cx/my.php?image=pontia268yi.jpg
Exhaust Side
http://www.bopengineering.com/images...ust_port_b.jpg
Intake Side
http://www.bopengineering.com/images...l_intake_b.jpg
I will post my results with before and after data when I am done.
http://www.gesslerheadporting.com/me...3800-head1.jpg
You may notice the port is not round; round ports are very weak on velocity at the lower lift ranges and only good for high RPM. This was the problem with the old Pontiac Ram Air V and Tunnel Port Heads cylinder heads; the ports flowed big numbers, they were round and you could almost fit a tennis ball in them. However, the did not flow at the lower and mid-lift numbers and they got outrun by the other makes. A port needs to build energy at the lower and mid-lift numbers to make power.
Take a look at a set of Ram Air V and Tunnel Port heads:
http://img55.echo.cx/my.php?image=pontia268yi.jpg
Exhaust Side
http://www.bopengineering.com/images...ust_port_b.jpg
Intake Side
http://www.bopengineering.com/images...l_intake_b.jpg
I will post my results with before and after data when I am done.
#30
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I always make a template of the best port configuration so I can duplicate the work on the remaining ports. I will take into consideration having a template available for personal use for the forum members. I am also reluctant since the last time I did so in another forum for a different car manufacturer make, a member used the template to start a porting business of his own and started to take credit for the hours I spent mapping, making molds and flowing different ports and testings various valve sizes, back cuts and angles.
By the way, I do not own a full-time business; in the past I did lots of racing and also race engine building and have access to a friend'* flow bench and related analysis equipment.
By the way, I do not own a full-time business; in the past I did lots of racing and also race engine building and have access to a friend'* flow bench and related analysis equipment.