Engine Setup Help? (E88/F54)

[dano]

Hi folks,

I'd like to get some input regarding a decision I have to make about the engine in my Z. I've searched through the archives, but haven't found anyone running the exact combo that I'm thinking about. I can infer things based on what I've read, but really want to make sure that I'm understanding it all correctly.

 

First some background information. I've got a freshly rebuilt L28ET (minus the E and T parts) in my carb'ed Z. Exact combo is: P90a head with hydraulic adjusters and F54 block with stock "turbo" dished pistons. As you can probably guess, it runs HORRIBLY. I now understand this is a result of extremely low (7.3:1) compression and a cam grind that doesn't work so well with carbs. I've also got an intact but well-worn L26 on the side. I believe it has the late-model E88 head based on the build date of the car (11/74).

 

At this point I just want to get the car back on the road without spending too much money. If possible I'd like to use part (or all) of the L28.

 

From reading and researching I think I have two options:

1. Reinstall L26 engine (it's old but still ran when I removed it last year).

2. Put the E88 head onto the F54 block.

 

I'd like if at all possible to do option 2 because it's a lot less work and I wouldn't have to get the L26 clutch redone. Plus I'd get to make use of the balancing job the machine shop did on the bottom end of the L28. For a variety of reasons adding the E and T parts isn't an option right now.

 

I used the awesome Z engine calculator at http://www.ozdat.com/ozdatonline/enginedesign/ to calculate compression ratios for the two engine configurations.

 

The L26 has a compression ratio of about 8.2:1 (I used the "L26" preset in the calculator for this). This is based on the calculator above and this post: http://forums.hybridz.org/index.php/topic/90777-l26-with-mn47-head/page__view__findpost__p__860272

 

The E88/F54 combination would, according to the calculator, also have a compression ratio of about 8.2:1. For this value I used the L28ET preset and changed the head to "L6:L26:E88".

 

Would the E88/F54 combination give comparable performance to the original L26? Or am I missing something?

 

Thanks in advance!

-Dan

[twofouroh]

Well, obviously it's a 2.8, which is ~7% bigger than a 2.6, so about 7% HP gain is my guess. It should be about the same as the f54/p90 on it now, everything else being equal.

[BluDestiny]

You will feel more kick based on the cam from the E88 than what you are driving now.

Edited May 19, 2011 by BluDestiny

[19762802+2]

If you end up swapping it out for the E88 you should probably get the head rebuilt with better valve seats, etc. If your not interested in ever making the motor into a turbo motor then you could raise the compression by getting some more head work done on the P90 as well.

 

http://datsunzgarage.com/p90/index.htm

http://datsunzgarage.com/p79/index.htm

 

These links cover some good information on building nice NA carbed motors.

[dano]

Thanks Guys!

 

Yes, I am planning to at least do the valve stem seals on the E88 if I go that route. I'll also get a quote on cleaning up the E88 (new seats, hot tank).

 

So far sounding like it will work better than what I've currently got in there .

 

As far as modifying the P90 I'm considering it, but will be done later.

 

Any other advice for an eager novice?

[rayaapp2]

Purchase a Nismo head gasket and run the E88 on the F54 bottom end. I believe the gasket thickness is .7mm which will bump the compression. Use the E88 cam if its in good shape still. It should be a 'C' cam, but you will have to verify the stamp on the back as it could have anything in it 35+ years later. That should bump you up to 8.6:1 compression and give you a little more bang for your buck. You just have to justify the cost of the Nismo MLS head gasket(around $200, but still available).

 

Im in the process of building the same bottom end .020" overbore with a E31 cylinder head which has a slightly smaller combustion chamber and which will result in a slightly higher compression ratio.

 

While doing the valve seats and IF you plan on continued use of the turbo bottom end you might try using the valves from the P90 head if the margins, stems, and other measurements are still good. The stock valves are stainless. The P90 valves would be slightly bigger(a few mm) and will offer slightly better flow, but it will be marginal with a stock setup and little to no chamber work as far as HP increase. Just an idea.

[dano]

Thanks rayaap2! Glad to hear I'm not the only one building something like this .

 

From everything I've read here I am going to go ahead with the E88/F54 combo.

 

I will double-check the cam, but am 99% sure it's the original 260 cam. I'm only the second owner and the previous owner wouldn't have done a cam swap. Thanks for the tip on the Nismo gasket but yeah I can't justify it right now. So I'm going to go 1mm felpro for some cheap compression.

 

I'm going to get quotes for cleaning up the head. Does $200-$300 sound reasonable? I'd have them hot tank it, change the valve guides and seats, and do a valve job.

[rayaapp2]

Thanks rayaap2! Glad to hear I'm not the only one building something like this .

 

From everything I've read here I am going to go ahead with the E88/F54 combo.

 

I will double-check the cam, but am 99% sure it's the original 260 cam. I'm only the second owner and the previous owner wouldn't have done a cam swap. Thanks for the tip on the Nismo gasket but yeah I can't justify it right now. So I'm going to go 1mm felpro for some cheap compression.

 

I'm going to get quotes for cleaning up the head. Does $200-$300 sound reasonable? I'd have them hot tank it, change the valve guides and seats, and do a valve job.

 

I had a shop hot tank the head, replace all the valve seats, check the guides, repair 2 small cracks, 3 angle grind the valves, lap the valves, leak test it, and surface 3 sides for around $360 at a reputable shop that 'needed' the work 3 hours from where I live. I could have done it locally, but it would have been much more. Being on the island Im not sure you will have many choices like that.

 

Im not sure what the 260z e88 head would have come with from the factory. Its probably the 'C' cam but could have been an 'A' or anything else they had on the shelf depending on where it was on the production line. Its generally from what I can tell accepted that they came with the 'C' though.

[mistah mofro]

Aren't the p90 valves to short to use on a E88 head?

[tyler031734]

The stock valves are stainless.

 

They must be a really low quality stainless. The P90 valves I had on the shelf snapped to my magnet as fast as I have ever seen any mild steel or chromoly. My .02

Edited June 12, 2011 by tyler031734

[SKiddell]

Not all stainless grades are non magnetic the term stainless is more a generic term used for steels that have very good corrosion resistance (usually have high chromium and nickel content)

 

To be completely non magnetic a material requires a magnetic permeability (MP) of 1, some of the high austenitic steel grades reduce this magnetic response to a value where it is not easily detected and thus appear to be non magnetic, however this 100% austenitic steel is often not practical as some ferrous component no matter how small is often present, typical MP numbers for austenitic stainless steels are in the region of >1.05, super high grade austenitic stainless steels used in research environments, MRI scanners etc. get as low as 1.005.

 

Martensitic stainless steels have noticeable magnetic properties but are still classified as "stainless" as they also have high corrosion resistance.

[tyler031734]

good to know

[madkaw]

I would try and pick-up an earlier e-88 head if you can find one cheap and redo it. The later e-88 chamber design is not that great and takes a lot of work to perform.