Author Topic: Tri Power  (Read 238 times)

Kelley W King

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Tri Power
« on: October 19, 2017, 06:15:54 PM »
Thinking of running a 427 tri power on my L78 just for cruise in shows. I have used rectangle port intakes over oval port heads, no problem. Can I use oval port intakes over rectangle port heads? Some power loss not a factor, just cruising and have way more power than tire now.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

BULLITT65

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Re: Tri Power
« Reply #1 on: October 20, 2017, 05:35:52 AM »
Not the most efficient as you mentioned but with the right set of gaskets it seems like it would work. If you swapped one way and the water jacket and ports lined up pretty close, it would seem you could do the same in reverse. Have I ever done it? "No."  That is out of my comfort zone. I have Mickey Moused some things on cars over the years to "make it work", but even if the car ran just a little inefficient, it would just rub me the wrong way.
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

Kelley W King

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Re: Tri Power
« Reply #2 on: October 20, 2017, 10:53:00 AM »
Looks like I lost the Ebay bid anyway. Might look for an oval port next time. I have never ran a big block tri power but I think it would have that day 2 cool factor. Keeping all the real stuff on the shelf if I do it.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

X33RS

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Re: Tri Power
« Reply #3 on: October 20, 2017, 01:23:04 PM »
. Can I use oval port intakes over rectangle port heads? .

This is generally the preferred method when trying to gain velocity in the intake track, at least it was 20 years ago.  Buddy of mine for years ran his street/strip 68 chevelle this way.  427 with square ports, then ran a Victor Jr. oval port intake on top.  Tony Bischoff (multiple EMC winner) built the engine and it made fantastic power for a small engine.  The all steel chevelle ran 10.60's at 125+ with a  small tire and stock suspension (no back half) and he drove it on the street everywhere.

BULLITT65

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Re: Tri Power
« Reply #4 on: October 20, 2017, 02:34:19 PM »
Impressive. I learned  something here then. I have been around racing, but not nearly as long as many of you. I had no idea this was used as an alternative or in even purposeful in racing. Thanks for the education.
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

Kelley W King

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Re: Tri Power
« Reply #5 on: October 20, 2017, 07:22:22 PM »
I have never thought about it. It seems that this would help the bottom end which is what a street car wants. My search parameters have grown wider.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

X33RS

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Re: Tri Power
« Reply #6 on: October 20, 2017, 08:09:43 PM »
Well, I don't know if it's an ideal way of making HP with all the aftermarket parts we have today.  I just know that trick used to be done decades ago and it worked under the right circumstances.
One detail about that engine that's worth mentioning, he ran a real set of L88 aluminum heads on it.  Back then there weren't a lot of good aftermarket options.  But now we have excellent aluminum heads available that don't need huge intake runner volume to flow big CFM.  Most new heads today are flowing better with smaller ports.

My square port AFR's are only 305cc intake runner (compared to stock GM stuff at 315-320+)  Yet my AFR's flow 370 cfm out of the box with no CNC work.  GM heads weren't even close to that.