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| V6 iron cylinder head (Page 11/12) |
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lordfiero
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JUN 02, 06:47 PM
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Middle Intake Manifold, MIM.. This was a big surprise.. I read many concerns about the goose neck on the upper intake manifold, but why worry about that when the MIM runners cant supply the heads with sufficient air anyhow.
Flow is down 20% with the setups below.
Separate MIM prepped for optimum measurements
Together with Fiero UIM
Together with Camaro UIM
The flow performance was so bad I had to measure the LIM again but with the same reults 
I dont think the MIM can be fixed by porting out the stock shapes any longer. This is a problem..
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lou_dias
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JUN 02, 09:17 PM
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I cut the top .3" off the MIM.
This opens the port(s) to the inside perhaps 1/8" and allows for better porting and polishing of that cross section. You'll need to cut the gaskets to take advantage of this.
I also cut .3" off the bottom of the TIM for similar reasons... You can see pics here in the first post: http://www.fiero.nl/forum/Forum2/HTML/075502.html[This message has been edited by lou_dias (edited 06-02-2019).]
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lordfiero
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JUN 09, 06:01 PM
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Yes cutting down the runner is an option or even slicing it to sections before porting, thanks for the input.
Unfortunately I need to get the flow up a lot..
At the moment Im working on the optional way of doing it, adding material 
I would like to add width but that is not possible when the runners are packed so xxxx close to each other.
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lou_dias
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JUN 10, 08:58 AM
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| quote | Originally posted by lordfiero:
Yes cutting down the runner is an option or even slicing it to sections before porting, thanks for the input.
Unfortunately I need to get the flow up a lot..
At the moment Im working on the optional way of doing it, adding material
I would like to add width but that is not possible when the runners are packed so xxxx close to each other. |
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Looking at my inner walls, you can see my ports are opened up more than your picture above.
The LIM shouldn't be a restriction when you're done. Remember, all these pieces were originally cast with 2.8L in mind...
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Will
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JUN 12, 12:32 PM
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Will
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JUN 12, 12:37 PM
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D-oh [This message has been edited by Will (edited 06-12-2019).]
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lou_dias
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JUN 12, 08:07 PM
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Classic.
What I couldn't convey then that I can now is about using water to flow bench. Water has a lot more mass than air and doesn't like to change direction. Air simply follows to the lower pressure area regardless of which direction that is in. Doesn't care so much about direction change and that's why your can increase flow with polishing more than a mild port with a rough polish.
So flow benching is a good guide to finding restrictions in the grand scheme of things but air will still outperform the expectations of a flow bench in many cases.
This goes back to the philosophical differences me and Rei and the OP have about the intake vane. I believe it's there to balance pressure around the valve as do a lot of engine builders but a flow bench will tell you that you increase flow by removing it. So I digress...[This message has been edited by lou_dias (edited 06-12-2019).]
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Dennis LaGrua
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JUN 13, 06:54 AM
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I've ported 3.4L P/R engine heads and there is a difference in performance but its not dramatic. I had to get around the remaining restrictions by adding a turbocharger with boost. IMO there is only so much that you can do to get these 60* V6 engines to breath really well. GM even went so far as to add new heads w quad valves in a DOHV configuration and got 215 HP. This is a decent step up for this engine but not near what other swapped engines can provide. Point is to not expect miracles when porting the V6 P/R engine heads. ------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "
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La fiera
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JUN 13, 09:19 PM
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| quote | Originally posted by lou_dias:
This goes back to the philosophical differences me and Rei and the OP have about the intake vane. I believe it's there to balance pressure around the valve as do a lot of engine builders but a flow bench will tell you that you increase flow by removing it. So I digress...
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Lou, the vane is there to promote air velocity which translate into torque but at high rpm it becomes a restriction. For a street driven car the vanes gives instant response, and great low end torque but at high RPM when air volume is needed, that's where the vane lacks. I know your engine and mine are totally diffent but look at the torque you are producing at about 3200rpm, its about 210ft/lbs and mine is making 230ft/lbs of torque. Not much difference! But look what happens at 4500rpms, you make about 196-197ft/lbs of torque and I make 300ft/lbs, there is a 103ft/lbs of torque difference at that RPM and the higher in the RPM band they go your power suffers more becase it can't only flow enough due to the vane restriction. If I were to put your heads on my engine I probably would've picked up 25-30ft/lbs more between 2000 and 3000rpms but after that I would probably loose them as fast past those RPMS. Plug one of your nostrals and run a sprint as fast as you can and measure how far and how fast you covered that distance. Then do the same test with both nostrals, that will give you an idea of the theory.
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lordfiero
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JUN 14, 05:32 PM
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The main problem with the LIM and MIM is not the area, it is the air stream direction. The LIM turns/rotates the air upwards and the MIM is an almost straight pipe. I can reduce the area and gain lots of flow at all pressures IF everything above the LIM (including fuel rail) are wasted in the garbage bin. I would like to keep a stock look so Im trying to find a way to make it work.
Most of those modified intakes have the same problem. I only seen one I believe in so far..
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