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r32-25t

R32 Gtr Long Term Love, Now Project


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On 30/07/2021 at 5:42 PM, r32-25t said:

Bay got blasted today 7D44A096-0B5B-4B47-9DD1-BEC7ECD53BF2.thumb.jpeg.0a273f55f37bc2a048de99fb81ccec26.jpeg

gets etch primer tomorrow and then paint during the week 

Nice!  Are you going to do any hole deleting or rough area smoothing or just lay the paint on as is?  Either way it will look stunning once it's done!

 

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On 03/08/2021 at 10:53 AM, Dose Pipe Sutututu said:

Curious on why you removed the squish pad?

Can of worms this topic. 
 

Got a theory on why to keep it or to remove it?

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As Paul said can of worms but by removing the squish pad it allows you to run much higher compression ratios without detonation becoming uncontrollable 

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Squish pads produce;

  • A required (read as "desirable") amount of turbulence in the mix right at the end of the compression stroke. This greatly improves mixture distribution and mixing at the point where it is getting ignited, leading to obvious desirable improvement of pretty much all the combustion parameters of interest.
  • A reduction in the surface area of the head and piston facing the flame at and near the moment of ignition. The tiny little volume of mixture trapped in there is a better compromise than the otherwise exposed but narrow corners all the way around the rest of the combustion chamber where it meets the edge of the piston. Small combustion chamber volumes and decreased surface area should cause improved resistance to detonation, rather than the commonly held opinion as expressed by R32-25t above. Which is not to say that once the usage of the engine is pushed waaay beyond where the OEM engineers expected it to be, that perhaps the hot edges of the squish pads do trigger detonation.

I'd be willing to believe the improvements in ignition triggering, ECU accuracy/speed and fuels (ie E85) have probably exposed the old belief as being more of a band-aid for problems with real causes elsewhere.

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On 03/08/2021 at 11:52 AM, r32-25t said:

As Paul said can of worms but by removing the squish pad it allows you to run much higher compression ratios without detonation becoming uncontrollable 

I know it's a touchy subject, however just really curious to hear other people's thoughts on this.

 

On 03/08/2021 at 12:01 PM, GTSBoy said:

I'd be willing to believe the improvements in ignition triggering, ECU accuracy/speed and fuels (ie E85) have probably exposed the old belief as being more of a band-aid for problems with real causes elsewhere.

My thoughts + most of these cars are running E85

 

The main issue was that in the past people threw on thicker than OEM head gaskets to lower the comp, at the same time without really thinking about increasing the squish area/volume as a by product of the thicker head gasket. This would indeed cause those undesirable outcomes with pre-ignition and hot spots.

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There are argument for and against removing them, everyone’s option will always be different. The cars I’ve seen with them removed seem to make more power which says they have better flow. 
 

the engine is not going to be a low comp dog, it’s compression ratio is going to be well above the factory 8.5:1 

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On 8/3/2021 at 12:39 PM, r32-25t said:

more power which says they have better flow

Not related to the squish pads. Different things.

On 8/3/2021 at 12:39 PM, r32-25t said:

the engine is not going to be a low comp dog

If that's in reference to what Dose said about thicker head gaskets, then also missing the point.

 

'Twere me, I'd be looking to increase the amount of squish in a modern engine build. Not decrease it.

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On 03/08/2021 at 3:23 PM, mlr said:

Why do people remove them.....??????

because it "can" lead to heat spots forming and pre-ignition happening, however this generally due to running thicker head gaskets to lower the comp for big boost.

Very 1990s way of tuning, nothing wrong with it but with E85, ECU and injector tech these days you would think there's no need to lower comp.

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On 03/08/2021 at 3:41 PM, Dose Pipe Sutututu said:

because it "can" lead to heat spots forming and pre-ignition happening, however this generally due to running thicker head gaskets to lower the comp for big boost.

Very 1990s way of tuning, nothing wrong with it but with E85, ECU and injector tech these days you would think there's no need to lower comp.

Yeah, to me it seems that removing them is removing an engineered design for better combustion 

Is it a proven thing that they are the real cause for "possible" detination when running 98

Or is it more a thing when running on the ragged edge of a good AFR?

To me, the sharper edges on valve reliefs would be more of a place to propagate hot spots and det???

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On 03/08/2021 at 3:41 PM, Dose Pipe Sutututu said:

because it "can" lead to heat spots forming and pre-ignition happening, however this generally due to running thicker head gaskets to lower the comp for big boost.

Very 1990s way of tuning, nothing wrong with it but with E85, ECU and injector tech these days you would think there's no need to lower comp.

Calculate the chamber volume and have pistons made to suit the increase in chamber volume to hit the target comp ratio.

I took the intake squish pad out when I built my head 10 years ago. 9.0:1 comp. Right or wrong thing to do, unsure. It’s hardly turned it into a dog though. 🤷‍♂️.

Interesting topic and one that never comes to a black and white answer.

 

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On 03/08/2021 at 4:14 PM, Piggaz said:

Calculate the chamber volume and have pistons made to suit the increase in chamber volume to hit the target comp ratio.

 

Sounds logical 

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