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L28ET Cam Swap


Zguy91

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Why not? That's the hot N/A cam and will move the power peak to a more sporting 6300 or so, with a big torque bump midrange. Really should wake up the characteristics of the stodgy turbo grind which is wheeze-o-matic above 5300...

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Why not? That's the hot N/A cam and will move the power peak to a more sporting 6300 or so, with a big torque bump midrange. Really should wake up the characteristics of the stodgy turbo grind which is wheeze-o-matic above 5300...

 

I was under the impression that the N/A, 'A' Cam was the way to go, or is the 'C' cam a better option ?

 

Nigel

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Was an "A" cam mentioned, or was it merely a question of is it worth trying a "C"?

 

Don't make this question into something it's not. IMO the Dual Carb L20A cam is better than any of them with more lift and duration, but he didn't ask that question, and I'm not going to befuddle the matter and stall him by suggesting he wait for some mythical 'hot ticket' camshaft.

 

Any of the early grinds from the 240 will work better in the L28ET to impart a sporting character to a rather sluglike engine performance curve.

 

Plus he can then confirm and independently testify that the engine DOES run like an L24, only with more power (waaay more power in the case of a turbo...) to put to rest the myth that the L28 'revs slow because of it's stroke'...

 

I digress...

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Stock NA cams work better than the stock turbo cam in my experience. good for another 500 rpms.

 

You can run NA cams as long as the cam is internally oiled (1977 on up). no spray bars on P90 heads. In other words, you need to use NA cam from a N47 or P79 head.

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Stock NA cams work better than the stock turbo cam in my experience. good for another 500 rpms.

 

You can run NA cams as long as the cam is internally oiled (1977 on up). no spray bars on P90 heads. In other words, you need to use NA cam from a N47 or P79 head.

 

 

Absolutely correct.

Though if you have access to an early set of cam towers with the spray you can simply swap the early towers for the late and run an early cam, or run a late internally oiled along with the early towers and spray bar. :wink:

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Was an "A" cam mentioned, or was it merely a question of is it worth trying a "C"?

 

Don't make this question into something it's not. IMO the Dual Carb L20A cam is better than any of them with more lift and duration, but he didn't ask that question, and I'm not going to befuddle the matter and stall him by suggesting he wait for some mythical 'hot ticket' camshaft.

 

Any of the early grinds from the 240 will work better in the L28ET to impart a sporting character to a rather sluglike engine performance curve.

 

Plus he can then confirm and independently testify that the engine DOES run like an L24, only with more power (waaay more power in the case of a turbo...) to put to rest the myth that the L28 'revs slow because of it's stroke'...

 

I digress...

 

 

Really dont want to venture even this far off topic, but I am totally in accordance with this stand point. Seen too many builds go way tangential based on "I gotta source this (insert bullshit rare part here)" because I read it's the greatest EvAR!

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What was the main reasoning behind Nissan designing in an "emphysema" cam for the L28 Turbos? Emissions? Fuel Efficiency? Low end torque? Limitations of the factory turbo technology at the time?

 

 

 

 

...Paul, or was it the limit of that tiny little power robbing throttle body they came with? < :D joke for Paul

 

 

Edited by cygnusx1
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What was the main reasoning behind Nissan designing in an "emphysema" cam for the L28 Turbos? Emissions? Fuel Efficiency? Low end torque? Limitations of the factory turbo technology at the time?

 

 

 

 

 

 

If I may....

 

I ran a L20A factory turbo grind and the thing was a torque monster in a stock NA L28 with 8.3 comp. Completely out of breath after 4.5k rpms but the torque off the line........ :o

 

Such a short cam would assist in all things mentioned above, enhancing low rpm torque with only a 7.8 to one factory turbo comp ratio.

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If I may....

 

I ran a L20A factory turbo grind and the thing was a torque monster in a stock NA L28 with 8.3 comp. Completely out of breath after 4.5k rpms but the torque off the line........ :o

 

Such a short cam would assist in all things mentioned above, enhancing low rpm torque with only a 7.8 to one factory turbo comp ratio.

 

Agreed, the "Butt Dyno" on the original purchasers of turbo zx's was mighty pleased with the torque provided, and since most of their efforts werent into the 6-7k rpm range (stop light shows and overtaking slow traffic) What more could they really ask for. From an engine designer's standpoint I can imagine having better efficiency down low would improve mileage in the operating band where most of engines use was, and customer satisfaction would ultimately be higher that way.

 

The same exact argument can be made for stock turbo size, and although ive never looked for it, im sure its on the forum here somewhere, or in the archives. Efficiency, and torque in the area which the car would be operating 99% of its time took precedence. If they wanted to, they could easily have had a cam like the L24 to push the powerband higher, and had a slightly more appropriate turbo like a t3/t04e.50 to help breathe better up there. But the gasoline wars win again. and performance falls to economy.

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Really dont want to venture even this far off topic, but I am totally in accordance with this stand point. Seen too many builds go way tangential based on "I gotta source this (insert bullshit rare part here)" because I read it's the greatest EvAR!

 

The reason I bought up the 'A' cam was, here in Australia, they are not that rare, the 1981-85 MR30 Skyline (L24e) has them, as well as the N47 head (mn47).

 

Nigel

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1) I didn't say anything about an "L20A Turbo Cam"---I said early L20A Dual Carb Cam. And to be pedantic, that other cam would be an L20ET cam, not 'L20A Turbo'... The performance is gotten with the extra 500 rpms of revvability that comes with the N/A cam...and the L20A dual Carb Cam is even more aggressive than the early L24 Dual Carb setup.

2) Chances are good if you have an early cam, you likely had the opportunity to take the towers, rockers and lash pads with you. I have never let the 'internal/external' oiling limit me as to what cam I installed. Changing the towers is a snap. And given the way the heads are savaged in SoCal JY's I'm figuring Pablo del Mecchanico con Yonke y mujeres figures that's the easy way to do the swap without every making the terrible mistake of swapping one for the other and seizing something up in short order.

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1) I didn't say anything about an "L20A Turbo Cam"---I said early L20A Dual Carb Cam. And to be pedantic, that other cam would be an L20ET cam, not 'L20A Turbo'...

 

Thanks Tony. I always enjoy my vocab lessons! Had to look that one up:

pe·dan·tic

–adjective

1. ostentatious in one's learning.

2. overly concerned with minute details or formalisms, esp. in teaching.

 

Which led me make sure I understood what I thought ostentatious meant:

os·ten·ta·tious 

–adjective

1. characterized by or given to pretentious or conspicuous show in an attempt to impress others: an ostentatious dresser.

2. (of actions, manner, qualities exhibited, etc.) intended to attract notice: Lady Bountiful's ostentatious charity.

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