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Trying to get more HP out of an L24.


CGraves

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He should be confident. He's been doing it since the early 80's. Rebello is the only shop in the world still developing the Datsun L series engines.

 

I think you mean R180 LSD. Yes, that is an extremely strong differential (and rare, and expensive). The breakaway pressure on the LSD can be shimmed for more HP. Be sure to run the proper gear oil in it though or it will chatter.

 

The stock 4 spd, if it's in good condition, should be fine as well.

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Isn't the 240Z r180 an open dif? 

 

The cheapest LSD R180 you can get is out of the 04-07 WRX sti, about $450. They are 27 spline on the stub ends. Both the 510 and 240 are 25 spline. Beta Motor Sports makes stub adaptors though. Those little pieces of billet aluminum set me back $550. 

 

http://www.futofab.com/index.php?option=com_content&view=article&id=173:r180-sti-stub-axles&catid=38:datsun-drivetrain&Itemid=122

 

http://www.futofab.com/index.php?option=com_content&view=category&layout=blog&id=38&Itemid=122

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Okay so I was under the impression the 240z came with an LSD but based on the responses I assume that's not true? My 240z definitely has an LSD in it but I'm not sure what it came from. I'm also not sure what diff I have in my 260z either. Is there any way to identify what diffs I have without taking them apart?

 

Assuming I've got the shitty diff what's the cheapest LSD I should look for that will handle this power easily. R180 or would a R200 be better?

 

EDIT: Okay so I did some calling around and I have an R180 open diff in my 260z and a mystery LSD in the 240z. Can anyone comment on the quality of the traction concepts r180 LSD conversion kit? If it's a safe buy if rather just spend the $350 and have the piece of mind instead of trusting a mystery LSD.

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@paradime

Yes I did quite a bit of searching but if you can point out a specific part of my post that you didn't like that would help me a lot.

 

That being said I'm gonna throw some stuff out there that I've learned in the past hour and anyone can feel free to tell me if I'm stupid.

 

That r180 LSD swap from Traction Concepts is garbage but my stock R180 should be fine to handle the power from the stroker motor. An R200 LSD should come out of a Z31 turbo made after '87 I believe* so if I want an LSD trying to source one from a junkyard should be the easiest thing to do. OR I could get an R180 LSD from a newer WRX, but they use a 27 spline stub so I would need an adapter to make that one work which would increase my costs significantly.

 

As for determining what kind of LSD I have in my 240z if the diff has a square back it's a R180 and if it has a round back it's a R200?

 

Also I can't find anything on HP numbers for a 4 speed but I know I'm fine according to Stoffregen but if anyone knows exactly how much HP they can handle reliably that would be fantastic.

 

Like I said I'm just throwing everything out there to make sure I'm right. If anyone knows otherwise feel free to correct me.

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Nissan didn't trust the 71B with the turbo engine but it was on the n/a 5 speed and automatic 280zx. So lets say that 175 hp would be the limit. The 71B 4 speed was last used in the '79zx (but in the '82 720 truck) and the '80 5 speed saw some small up grades. As far as the Z car is concerned it had reached it's useful limit but for trucks with 2.4 liter displacement 4 cylinder engines and the CA18ET in the 200sx it was fine and received even more up grades.

 

If you want something that handles 200 hp then get a 71C transmission and put an L series front case on it.  It was used in the n/a 300zx with the VG30E engine and is reported to reliably handle 400 hp in turbo KA 240sx. It will easily handle 200 hp.  

 

Here... http://zhome.com/ZCMnL/tech/240SX5spd/transmission.htm 

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@mike

 

Would the 71b hold up for daily use until I get time to source a 71c assuming I'm not driving it hard at all? Or is it advisable to just wait it out?

 

Also I'd just like to say thanks to everyone to dealing with all my questions so far. I'm really glad I found this website!

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@paradime

Yes I did quite a bit of searching but if you can point out a specific part of my post that you didn't like that would help me a lot.

 

Nothing I didn't like, just wanted to know what you've researched.

 

Remember, you don't have to limit your research to 240Zs, the 510 also uses the same dif. Check out the510realm, and Dime Quarterly as great resources. 

 

The reason I suggest the R180 out of a WRX sti is the cheapest option is they are newer, not VLSDs, and more likely to be in good condition. I realize that is a subjective opinion, but aside form getting very lucky and finding an older reliable R180 LSD that will actually handle your 200+hp 3'0, the less expensive option may be you get what you pay for.  

 

The LONGNOSE R200 LSD out of a 87-89 300ZX Turbo is a bulletproof overkill option but is much heavier, and requires a custom mustache bar and other fiddly bits. 

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Another update. My friend is swapping his s13 to a 2jz so he doesn't need his trans anymore so he sold it to me.

 

I also might get his R200 if it's an LSD. So I guess we'll be seeing a build thread in about a month or so.

 

Also while I'm at it should I snag his driveshaft? Or if I get mine shortened would it handle the HP I'm making?

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Only came in viscous LSD. LSD with shitty gear ratios is way worse that no LSD at all. As it turns out it's 4.083 ratio....not bad. I wouldn't even worry about LSD for 200hp. It's not making 200 hp on take offs but at 7K.

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There are only two ways to verify if you have a limited slip or not. Neither of them involve a visual inspection of the complete assembled diff with the cover on.

 

First method is to pull the cover and get a visual verification. They are pretty easy to spot. This is a good time to check your R&P ratio.

 

Second method requires getting both rear wheels off the ground. Spin a tire by hand. The opposite tire should spin the same direction, and may or may not be able to be moved the opposite direction. This is also a good time to check your R&P ratio.

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Just get some good tires and itll only spin for like 10 feet with the open diff..

 

K maybe not a 100 shot on a stock l24 but i bet 50 or 75 would hold.

 

Next month im turning mine up to 100 in the 4 banger, and praying to the connecting rod gods

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