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KamakSun

Closed chamber hp gains?

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Hi fellow ratsunners,

 

I just dropped a stock closed chamber head off to an engine rebuilder. 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.

 

Thank you,

 

Kamaksun

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does he know much about Datsuns?

the old style L16 mani flows like a tube header without the exhaust leaks of a lot of them out there.

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He does. I gave him my mikuni manifold to match to. Photos of the exhaust options are in my previous posts.

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Closed camb can help stop pinging. But yes the full benefit would need those mods.

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closed chamber is better. less pinging than a open chamber.

 

 

yes side drafts carb and cam and porting. $$$$$$$ for a extra 4 to 20 hp

 

 

Fuck the header. cast manifold will last forever.

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My header has lasted at least 20 years......

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Hi fellow ratsunners,

 

I just dropped a stock closed chamber head off to an engine rebuilder. 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.

 

Thank you,

 

Kamaksun

, he could just be biased and used to putting headers on his cars. A friend of mine and go fishing a lot and he swears up and down about lures being more effective than bait. I told him that lures have its place like bait. If its windy you will have a hard time casting lures. Anywho, stay with stock exaust and 2 inch pipe w turbo mufflers is good to go.

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The closed chamber head only works properly if you have flattop pistons. This gives you maximum quench and swirl to homogenize the mixture and reduce hot spots. If you have any dish (usually L16s are 7cc) it does very little. The L16SSS and L18SSS had flattops.

 

There are several closed chamber heads but if you have the L16 or L18SSS head there is no need to port as they are already at 1.5" intake.

 

 

L16SSS compression is............... 9.29

L16 with stock head..................... 8.58

L16 with closed chamber head.... 8.21.... this is because the closed chamber head is larger than the stock head. You are going to lose power here. Does your machinist know this???? You may be able to mill the head down to get some of the compression back but you are starting in the hole.

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Domed piston l20b, u67 closed chamber head. Machinist is going to mill it carefully to ensure valve clearance

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Have you done the math for compression ratio? Flat tops are probably better than dome unless you want the higher comprssion ratio and extra effort....

Also for reference I have 84mm dome piston in my l16 with a closed chamber w53 head.... I had do so a considerable amount of work to clearance the walls of the combustion area so the piston wouldn't contact the head, I even run a .05 shim on my spark plugs . I ended up at 10.7 to 1

I also am stuck running 93 octain...

Just look at the end result, and your buget.what are you trying to do with this motor? That should determine what need...

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Domed piston l20b, u67 closed chamber head. Machinist is going to mill it carefully to ensure valve clearance

What do they plan on milling?

Head or the piston?

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Domed piston l20b, u67 closed chamber head. Machinist is going to mill it carefully to ensure valve clearance

 

All I had to go on was the 510. Any more missing info??

 

 

There are no closed chamber U67 heads.

 

Are you now going to say it was custom welded up???

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It happens. A good head.

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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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Id consider lighting the fire

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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.

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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.

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