# Unbalanced head ports = diving torque curve??
**URL:** https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373
**Category:** PittSpeed Automotive
**Created:** [January 12, 2007, 4:21pm UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373 "2007-01-12T16:21:20Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)
#### Post date: [January 12, 2007, 4:21pm UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/1 "2007-01-12T16:21:20Z")
I wanna discuss a few things here.
1. Talk to me about balanceing cylinder head runners. How important is it to get the intake side to flow the same as the exhaust?
2. My fellow alltrac’iens show me something in dyno graphs, a diving torque curve after peak. I tried to find some examples:
[http://www.cj-motorsports.com/camtest.htm](http://www.cj-motorsports.com/camtest.htm)
* * *
[http://img169.imageshack.us/img169/246/philipalltracgt3.jpg](http://img169.imageshack.us/img169/246/philipalltracgt3.jpg)
The curve is jagged because my wire to the distributor has a hole in it now. This is with all water injection (no meth), loner turbo from KO Racing until I get mine rebuilt, none of my inconel heat shields, and a few other things that need to be fixed. Here is the set-up for now.
Engine: Rebuild to Stock specs
Intake Manifold: Stock
Exhaust Manifold: Stock
Turbo: KO Racing T3/T4 Kit
HG: 1.2mm TTE ML
Cams: HKS 264, HKS Springs, Shimless Buckets
Exhuast: Custom 3in
Clutch: Clutchmasters Stage 3
Flywheel: Stock
Fuel Injectors: Stock Oversized to 880cc
Fuel Rail: Wolfkatz Side Feed
FPR/Lines: Stock
Fuel Pump: Walbro 255
Intercooler: Big FMIC, with 2.25 custom piping
WI: Aquamist 2d
EMS: AEM
Sensors: Intake Air temp sensor, Single Channel Wideband O2 sensor, 3 BAR MAP sensor
* * *
[ ](http://www.koracing.net/img/Santesson18psiSB46vsTD06Pump.jpg)
…and these are modded cars, some heavily… more stock dyno’s that i can’t seem to find right now are much worse looking.
After thinking about what might cause the 3sgte to produce, I remembered the ports in the head.
INTAKE:
EXHAUST:
It _appears_ that the intake is gigantic compared to the exhaust. So, does this mean that there could be signifigantly less flow out the exhaust side, making it unable to empty the cylinder at progressively higher rpms?
I’ve seen big turbo’s, ive seen stock… i’ve seen big cams, i’ve seen stock… they all seem to have the same torque curve symtome. This is where i’ve come to. Let me know what youns think.
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### Author:  [@JackdUp](https://forums.speedlife.net/u/JackdUp)
#### Post date: [January 12, 2007, 4:28pm UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/2 "2007-01-12T16:28:59Z")
Why are exhaust valves smaller than intake valves?
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### Author:  [@Dominator](https://forums.speedlife.net/u/Dominator)
#### Post date: [January 12, 2007, 7:41pm UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/3 "2007-01-12T19:41:33Z")
Exhaust needs to be smaller. Somthing like 70% of what intake flows. Exhaust comes out alot eiser than intake comes in.
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### Author:  [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)
#### Post date: [January 13, 2007, 5:09am UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/4 "2007-01-13T05:09:40Z")
ight, so thats thrown completely out the window. in that case, my head is probably just fine?
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### Author:  [@Dominator](https://forums.speedlife.net/u/Dominator)
#### Post date: [January 13, 2007, 9:36am UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/5 "2007-01-13T09:36:42Z")
might be an optical illusion but it looks as though you gasket matched and didn’t blend it far enough down the runners. Taper is good for premoting velocity but a bulbus ramp can creat an anyurism in the flow path.
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### Author:  [@danl](https://forums.speedlife.net/u/danl)
#### Post date: [January 13, 2007, 12:05pm UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/6 "2007-01-13T12:05:04Z")
The size of the ports has everything to do with inertia and trying to maximize volumetric efficiency by maximizing the forces of inertia. What you want to do is inertia match the ports. A cold air has more mass per volume (PV=nRT). Therefore it can move at a slower speed and provide a certain amount of inertia (bowling ball at 1mph). The exhaust gas is much warmer and has much less mass per volume. Therefore it has to move much faster to achieve the same inertia (golf ball at 10mph). This is a major limitation of flow benches. Since the flow is steady state you have no way to account for inertia.
Then you have to worry about the air moving so fast that it becomes turbulent and does not move well. You also have to manipulate surface textures to try to keep air from going turbulent.
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### Author:  [@imported\_gearhead](https://forums.speedlife.net/u/imported_gearhead)
#### Post date: [January 14, 2007, 8:30am UTC](https://forums.speedlife.net/t/unbalanced-head-ports-diving-torque-curve/187373/7 "2007-01-14T08:30:16Z")
> [@I \<3 Broncos](https://forums.speedlife.net/t/i-3-broncos/27244/7):
>
> might be an optical illusion but it looks as though you gasket matched and didn’t blend it far enough down the runners. Taper is good for premoting velocity but a bulbus ramp can creat an anyurism in the flow path.
I dont know how far you should go. The intake ports are so gigantic, its smoothed to the bottle neck. What do you mena by “bulbus ramp”. The material you’d take out to open the venturi part of that head aka bottle neck doesn’t appear to be there
> [@what to do in the Buff](https://forums.speedlife.net/t/what-to-do-in-the-buff/27253/2):
>
> The size of the ports has everything to do with inertia and trying to maximize volumetric efficiency by maximizing the forces of inertia. What you want to do is inertia match the ports. A cold air has more mass per volume (PV=nRT). Therefore it can move at a slower speed and provide a certain amount of inertia (bowling ball at 1mph). The exhaust gas is much warmer and has much less mass per volume. Therefore it has to move much faster to achieve the same inertia (golf ball at 10mph). This is a major limitation of flow benches. Since the flow is steady state you have no way to account for inertia.
>
> Then you have to worry about the air moving so fast that it becomes turbulent and does not move well. You also have to manipulate surface textures to try to keep air from going turbulent.
I understand what your saying here… Now, what would be a good way to figure out if the runners are effecting the loss of torque at all?
What about measuring pressure in the exhaust manifold? then before and after the turbo?
I still think that the head as something to do with it… maybe cam profile, but that cam test didn’t do anything for me. Whenever you look at other heads, they _appear_ to be more similar in size. The ONLY other head I can think of that has big intakes and little exhausts are off of 5.0 mustang motors. All my chevy’s, hondas, etc arn’t as differenciated.