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Mild cam for turbo and n/a


HuD 91gt

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Hello,

 

I'm about on my 5th plan for an engine build right now. Im currently building the bottom end of an F54 block with oversized flat top pistons.

 

Original plan was to use my N47 head, which needs new valve train, a (round port)header etc. looking at the costs, I think I am going to purchase a local L28et and rebuild the P90 head for the time being and essentially create a overbored stock 280zx motor with square ports.

 

I will eventually use the rest of the accessories to turbo the motor with the flat top pistons as I believe it will create a nice streetable motor.

 

What I'm looking for is a mild performance cam which will be suitable for the vehicle in the n/a application, and also will be suitable for the motor once turbo charged. From what I've read, a cam with minimal overlap would be desirable.

 

Can I assume any of the "stage 1" cams would be ok for this sort of application, secondly should I even bother? The turbo cam would be fairly anaemic in a n/a application. My other option is the stock cam from my L24 motor (I forget the code stamped on it, but it is the standard version, not the rare one). Personally I'd rather get my N47 cam reground rather then mix matching parts from my complete l24 motor. But it is an option.

 

Any input is appreciated.

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I would encourage you to not do one more thing until you have a definite plan. A turbo build and an NA build are different enough that you are better off picking a direction and committing. Any half measures you do are going to be disappointing and set back your ultimate end game.

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Completely understandable and sort of expected.  Considering my end goal is not an extremely high powered machine, I figured a slow adaptation from a N/A to the turbo variety would be acceptable.  As suggested above, the A-C cams would be completely acceptable and work for all instances.  But I specifically have a cam which is worn and needs a regrind.  There must be some sort of combination which may improve performance over trying to imitate the original N/A cam?  As I said before, I do have an L24 engine laying around, but I don't want to start piecing it out. 

 

The idea that people use the N/A cams in the turbo motors to get a "Sportier" power band leads me to believe there is a cam which works for both instances.  Will it be an outright performer in both?  No, but thats not exactly what i'm looking for.

Edited by HuD 91gt
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I guess I don't really see how one slowly adds a turbo. You can slowly acquire all the parts, but it's either installed or it isn't. If you're buying a complete l28et, it seems to me that whatever gains you are getting from the overbore on your old block could be had by cranking the boost, and any money you would be spending on that cam regrind could be better spent on an intercooler?

Edited by veritech-z
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If you have the option run the l28et with a intercooler at 12 psi and enjoy it. if you feel you need more power later go to megasquirt and a t3/t4 50 trim and some 450cc injectors and run upto 20 psi with big cam and go v8 killing like me but most are fine with stock intercooled 12psi l28et because they feel real fast for not alot of cash. good luck!!!

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I guess I don't really see how one slowly adds a turbo. You can slowly acquire all the parts, but it's either installed or it isn't. If you're buying a complete l28et, it seems to me that whatever gains you are getting from the overbore on your old block could be had by cranking the boost, and any money you would be spending on that cam regrind could be better spent on an intercooler?

Totally understandable.   My situation is that I can't really do the entire thing at once.  I don't have the space.  If I were to take on a project like that there are way too many variables to go wrong.

 

I live in a major city, in an apartment.  Space for working on projects is time limited.  I can't be without a running vehicle for long (I just can't leave it).  I am starting with a 240z.   L28et requires, an update to the entire fuel system, from tank to injection.  Dealing with a different ignition, not to mention the unknown condition junkyard motor.  

For me, going in steps 1)Building a moderate compression N/A motor on carbs 2) Fuel system 3) Engine management (Megasquirt) 4) Finally complete the injection/ignition and install the turbo portion.

 

Doing it this way enables me to slowly go through the project, work out the bugs then carry onto the next step. It may not make sense for most, but it does for me.

 

Rebuilding the motor is the base of the project, first and foremost.  I am simply asking if there is a mild grind available which I will require for step 1), the N/A carb'd motor which may work better in the turbo application then the turbo cam itself but also be able to run to a satisfactory level in the N/A setup for the time being.  Since I have a stock unusable N/A cam and I don't particularly want to run the turbo cam in the N/A motor, I may as well get one which will work in the turbo application as well.  Make sense?

Edited by HuD 91gt
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I've been in that situation as well (car can never not be running), and I did a parking lot turbo install. It is definitely easier to just swap the manifolds than to pull the engine if you don't have a hoist or the space. I have also done a parking lot head swap, and that is also easier than pulling the whole engine under those conditions.

 

So is your car running now, and you have an extra cam you need to do something with, or is your car not running, and you have to get this cam situation resolved regardless?

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Here is an interesting article that talks about cam selection for a turbo motor:

http://www.hotrod.com/how-to/engine/ctrp-1106-turbo-camshaft-guide/

 

This article alleges that with a modern, high-efficiency turbo you can treat the rest of your build the same way you would for an NA build. That being said, if you are bolting on a stock l28et setup, that probably doesn't qualify as a "modern, high efficiency turbo."

 

For me, the takeaway is probably to do what redzedturbo suggested and just get on the horn with Isky or somebody for a recommendation.

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Great article!  Thanks for the read. The car is currently off the road right now and i'm trying to get it back to being roadworthy as soon as possible.  The bottom end is at the machine shop getting inspected, and I need to send out my worn out cam shortly.  Your probably right, a quick call to ISKY or the like will get me on the right track.  Cheers.

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From what I understand, N/A and turbo are two different animals for the compression ratio of the engine. If you're rebuilding, you need to seriously focus on either turbo OR N/A. N/A you'll be looking at about 10:1 compression, Turbo you'll be looking at about 7.5:1 compression plus boost. If you build a 8.5:1 N/A motor because you're planning to maybe perhaps if you feel like it maybe turbo in the future then you'll be disappointed with the N/A build and limited in psi or run into dangerous ground when you turbocharge.

 

Don't even think about turbocharging a 9:1+ N/A L28 unless you plan to run race gas.

Edited by Simeo
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^ please don't spread inaccurate information to what could be unknowledgeable people. There are plenty of people running L Series turbo engines at ~9:1 compression.

 

Just because something is not the norm, doesn't not mean it will not work.

Edited by HuD 91gt
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