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Old 10-11-2015, 05:54 AM   #1
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Default Cracked Flat Top Intake Manifold

Hi Gents,

I have cracked my Flat Top Intake manifold on the corner closest to throttle body. I think I may have reversed the Hondata Teflon gasket. Regardless as soon as torqued it down to 18 ft-lbs, it cracked. You can see the pictures. Any suggestions on how to fix it?

Thanks.
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Cracked Flat Top Intake Manifold-image1.jpg   Cracked Flat Top Intake Manifold-image4.jpg   Cracked Flat Top Intake Manifold-image5.jpg   Cracked Flat Top Intake Manifold-image2.jpg  
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Old 10-11-2015, 10:40 AM   #2
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A welder
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Old 10-11-2015, 04:29 PM   #3
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How soft it that spacer? It looks deformed from compression. Looks like less torque is needed when using it.
Weld it up while bolted up to a flat plate, then check the flange for flatness.

Last edited by 99mx5; 10-11-2015 at 04:39 PM.
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Old 10-11-2015, 04:37 PM   #4
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Quote:
Originally Posted by 99mx5 View Post
Are you using the intake manifold brace?

I was thinking what could cause that to happen.
- over-torqued bolts
- soft heat-isolation spacer
- no manifold brace
- combination of the above coupled with engine vibration
He cracked it torquing it down.

Bad torque wrench?
Something stuck underneath it?
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Old 10-11-2015, 04:41 PM   #5
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Yeah, I realized it then changed my post. You beat me to it.
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Old 10-11-2015, 08:28 PM   #6
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Quote:
Originally Posted by aidandj View Post
He cracked it torquing it down.

Bad torque wrench?
Something stuck underneath it?
I had definitely flipped the Hondata Teflon gasket. The additional support for the end that cracked, was on the opposite corner.
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Old 10-11-2015, 09:51 PM   #7
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Why are you using one of those gaskets in the first place?
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Old 10-11-2015, 10:03 PM   #8
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Why are you using one of those gaskets in the first place?
The believe is that it helps prevent heat transfer from the head to the intake manifold. How true or how much difference it makes, I am not sure.
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Old 10-11-2015, 10:22 PM   #9
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Old 10-11-2015, 10:52 PM   #10
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Quote:
Originally Posted by orlmiata View Post
The believe is that it helps prevent heat transfer from the head to the intake manifold. How true or how much difference it makes, I am not sure.
Think about the airflow being ingested by the engine and the speed of that air. Heat transfer has a time component. How hot does the intake manifold really get? How long is the air actually in contact with the intake manifold? What percentage of the air actually picks up any appreciable amount of heat, and what percentage of the air ends up insulated from the intake manifold by the air around it?

Take your IM and a scrap cylinder head to a competent welder. Bolt it down and weld it back up, then throw that silly phenolic spacer away.
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Old 10-12-2015, 10:07 AM   #11
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I put one of those gaskets on my wife's RSX several years ago and tested the temps before and after. The gasket definitely makes a difference in IM temps and while that may not show significant gains I can't imagine it's hurting anything. Added bonus on a miata, it gives you another 1/4" or so of room to get your rerouted coolant return past your intake piping.

I don't know if they're worth running out to buy, but I certainly wouldn't throw it away if you already have one.

Quote:
Hondata IMG temp variations
Not sure if anyone has done this before, but I figured I'd post up my results. I took some before and after temperature readings from the intake manifold to see how the gasket would affect manifold temps. All tests were done mid-day in south FL, similarly hot as hell for all 4 tests (2 before, 2 after) on a type S with only raceheader, no other mods. Along with the gasket I rerouted the coolant lines to the throttle-body as described in hondata's instructions with the gasket.

Temperatures were taken from 3 points that were marked on the manifold and taken with a infra-red temperature gun. Sample points are seen below:



Before temperatures:
Point 1: 157, 159
Point 2: 138, 140
Point 3: 137, 137

After temperatures:
Point 1: 144, 146
Point 2: 132, 133
Point 3: 131, 131

Temperatures close to the head were down 11-13 degrees. Farther away from the manifold temperatures are less drastic (as expected), 6-7 degrees. The test made me curious what kind of difference would be seen where the manifold mates to the head, I'd expect an even wider margin in the results there.
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Old 10-12-2015, 12:13 PM   #12
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Originally Posted by pdexta View Post
I put one of those gaskets on my wife's RSX several years ago and tested the temps before and after. The gasket definitely makes a difference in IM temps and while that may not show significant gains I can't imagine it's hurting anything.
The temperature of the manifold is irrelevant. What matters is the temperature of the air entering the engine. The air entering the engine is traveling very quickly, and most of it never comes in contact with the intake manifold in the first place. Reducing the intake manifold's temperature will have virtually no effect on the temperature of the air entering the engine. The "gains", if any, would be virtually impossible to measure.

This thread is about a guy who cracked an ear off his $600 Squaretop while trying to install one of these gaskets, so I'm pretty sure he hurt something.
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Old 10-12-2015, 01:03 PM   #13
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Quote:
Originally Posted by Savington View Post
This thread is about a guy who cracked an ear off his $600 Squaretop while trying to install one of these gaskets, so I'm pretty sure he hurt something.
He installed it backwards, that's hardly the parts fault.
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Old 10-12-2015, 02:04 PM   #14
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Quote:
Originally Posted by orlmiata View Post
Hi Gents,

I have cracked my Flat Top Intake manifold on the corner closest to throttle body. I think I may have reversed the Hondata Teflon gasket. Regardless as soon as torqued it down to 18 ft-lbs, it cracked. You can see the pictures. Any suggestions on how to fix it?

Thanks.
Welder. Ditch the gasket. It took a long time for us to begin experiencing issues with the Hondata gaskets on our cars. We dropped them from our website when we did.
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Old 10-12-2015, 10:51 PM   #15
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Quote:
Originally Posted by Savington View Post
The temperature of the manifold is irrelevant. What matters is the temperature of the air entering the engine. The air entering the engine is traveling very quickly, and most of it never comes in contact with the intake manifold in the first place. Reducing the intake manifold's temperature will have virtually no effect on the temperature of the air entering the engine. The "gains", if any, would be virtually impossible to measure.

This thread is about a guy who cracked an ear off his $600 Squaretop while trying to install one of these gaskets, so I'm pretty sure he hurt something.
I must respectfully disagree. I run a similar but thinner gasket, and the manifold stays cool to the touch. We sat 3 ice cubes on the manifold once, it was worth 3 hp on the dyno on a 90+ degree day.
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Old 10-12-2015, 11:13 PM   #16
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Quote:
Originally Posted by Stealth97 View Post
I must respectfully disagree. I run a similar but thinner gasket, and the manifold stays cool to the touch. We sat 3 ice cubes on the manifold once, it was worth 3 hp on the dyno on a 90+ degree day.
Most will claim that 3hp can easily be the variance between 2 pulls, and they'd be right.

I'm sure you knew that and did multiple back to back testing to disprove this......................................right?
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Old 10-13-2015, 01:17 PM   #17
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I've been running a squaretop with one of those gaskets for years now. Is this a reliability issue?

The manifold is off the head for now but I'm wondering if I should just omit it when I reassemble everything. Also, besides the reliability improvement (ie, the broken tb issue), are there any other real upsides to doing the skunk2 throttle on a squaretop and porting the intake to match?

I mean, if I'm running 18 psi of boost measured at the intake manifold, won't I just be reducing the pressure ratio further up the line (ie, less restriction for the compressor to push against to make that level of manifold pressure)?
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Old 10-13-2015, 01:22 PM   #18
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If the throttle body is a restriction then yes it would help. Most people do it for reliability.
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Old 10-13-2015, 02:59 PM   #19
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AIUI, the throttle body's flow is not a major restriction for a turbo because you're compressing the air before it flows through it. It is a lot more significant on a positive displacement supercharger where you have to suck a larger volume of lower pressure air through it.

--Ian
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Old 10-13-2015, 03:01 PM   #20
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Still a restriction. Probably not an issue for the amount if air a Miata flows. But still a restriction.
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