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Closed chamber hp gains?


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#21 datzenmike

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Posted 07 September 2017 - 07:21 PM

Photo of the receipt, I forgot that this is ratsun

 

If you mean the lack of pictures from PB, that's PB's fuck up. I no longer have anything to do with them. I wouldn't piss on them if they caught on fire.


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#22 Lockleaf

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Posted 07 September 2017 - 07:34 PM

Id consider lighting the fire

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#23 Stoffregen Motorsports

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Posted 07 September 2017 - 07:42 PM

A good engine builder will know what to do without you having to tell him.

A shitty engine builder will complain about the parts you brought him

Have you given him the chance to tell you what needs to be done? He should know that 10:1 cr is a good street ratio and he should know how to achieve that without any input.

#24 KamakSun

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Posted 08 September 2017 - 08:40 AM

What do you use to post pics?

#25 Stoffregen Motorsports

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Posted 08 September 2017 - 09:34 AM

I use Photobucket, but since I have been a paying customer for a few years, they grandfathered me in with all their new rule changes. If you want to sign up with them as a new customer, and be able to post pics, you now need to ante up for the $400 per year subscription.

 

Other guys here are using Imagur.



#26 datzenmike

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Posted 08 September 2017 - 10:26 AM

I'm using Imgur but have been waiting to see where the chips fall. Recently have been using it more and more.... holy shit, fast and simple


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#27 Stoffregen Motorsports

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Posted 08 September 2017 - 11:10 AM

It takes me eight clicks to get one image copied and pasted from PB to any forum.

 

Really quite a joke.



#28 datzenmike

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Posted 08 September 2017 - 11:19 AM

...and 80 seconds to get into PB, then wait and wait and fail to load, and wait and load image and go and try to find it in your album. I can go to Imgur, then find an image in my computer, load and copy it and post it in Ratsun in less than a minute..


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#29 KamakSun

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Posted 08 September 2017 - 12:35 PM

https://i.imgur.com/rICEyZb.jpg

#30 KamakSun

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Posted 08 September 2017 - 12:36 PM

Please let me know if this worked.

If it worked, what's the apx compression?

#31 Stoffregen Motorsports

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Posted 08 September 2017 - 03:34 PM

I see a link, but no image.



#32 Stoffregen Motorsports

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Posted 08 September 2017 - 03:35 PM

...and 80 seconds to get into PB, then wait and wait and fail to load, and wait and load image and go and try to find it in your album. I can go to Imgur, then find an image in my computer, load and copy it and post it in Ratsun in less than a minute..

Really? Imagur is that easy? You can upload from your PC directly to a forum?

 

Sounds like you know your PB. That's exactly what happens, every time.



#33 datzenmike

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Posted 08 September 2017 - 03:48 PM

...and 80 seconds to get into PB, then wait and wait and fail to load, and wait and load image and go and try to find it in your album. I can go to Imgur, then find an image in my computer, load and copy it and post it in Ratsun in less than a minute..

 

Not so fast. :lol:   I can go there, find an image in my computer that I want, load it (into imgur) copy it and post in Ratsun. (make that 80 seconds fro sure)

 

 

 

 

I'd say it's working. The A87 has 33.75mm intake ports so not quite as large as the U67's at just under 35mm. The intake valves are almost 42mm and the exhaust valves are 33mm or 35mm. I'm guessing the 33mm were on the heads used on the L18 and the 35mm were for use on the L20B. I've never seen an A87 on a stock L20B but I hear it was only the very early ones. If that's the case the '74 610 may be the one. After 40+ years one could have been swapped on to any L20B.

 

rICEyZb.jpg


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#34 datzenmike

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Posted 08 September 2017 - 04:03 PM

Can't work out the compression without knowing the volume of the piston dome, the piston pin height and the volume of the closed chamber head. Often they have been previously milled down.

 

A stock L20B with a closed chamber head would be... 8.9

Above with flattop pistons........................................... 10.68 anything with a dome will be much higher.


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#35 KamakSun

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Posted 08 September 2017 - 06:12 PM

I'm just screwing up all around, reverse dome aka dished.

#36 datzenmike

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Posted 08 September 2017 - 06:44 PM

It's ok. Are these stock L20B then? A 1mm overbore only just tops 9 to 1


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#37 KamakSun

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Posted 08 September 2017 - 08:12 PM

I have no idea of the engines origin. The current head is the rare one that has no significance to it, u60. I think you told me it is the same as a u67

#38 datzenmike

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Posted 08 September 2017 - 08:42 PM

So L20B and closed chamber head. Well compression will be about 8.9.The advantage of a closed chamber head will not be fully utilized as the pistons are dished. You do have the compression.

 

The tighter you squeeze the fuel and air the faster it burns, the stronger the explosion and the more energy that can be put to work moving a piston. You are simply making more efficient use of your fuel. For an engine with 8.4 compression (a stock L20B) increasing it upwards one point will generally get you about 4% more hp. The next point is a little less than 4%, the next point a little less and so on. This is because you are getting closer and closer to the ideal efficiency. Going from 8.4 to 8.9 is worth about 2-3 hp. 


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#39 hang_510

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Posted 13 September 2017 - 10:16 PM

The machinist said that not a lot of gains are to be had unless the head is ported, valves and springs changed and a hotter cam installed. Is this correct?
Additionally, he wants me to switch to headers and this board told me to keep the cast manifold.

He is correct.
The board is correct.

I had 4-2-1 header and like the cast manifold better.

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#40 Three B's Racing

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Posted 14 September 2017 - 04:37 AM

9:1 compression will work great. Put your money into head work, cam, valves, lubrication and remember, your engine is nothing but a air pump, the better it breathes the more output you get.