PurePontiacKid Posted November 21, 2008 Share Posted November 21, 2008 Hey, I've been doing some research on the engine that I want to build for my 280ZX... I want to go turbo, and I want to throw lots of boost at this car when I get the motor built... I found that the '77-'80 motors had dished pistons (you already know that) and the P79/P90 heads have larger combustion chambers than the other heads (you already know that, too) And I was wondering if it would be a good idea to mate the early motor, with the dished pistons with the late model large chamber heads (I read somewhere that it would hurt the quench in the head) for a lower static compression ratio? I also plan to do some mild porting/ polishing work on the head, as well;-) So do guys have any thoughts on this? Thanks! Quote Link to comment Share on other sites More sharing options...
cockerstar Posted November 22, 2008 Share Posted November 22, 2008 iirc, going with dished pistons really minimizes the importance of quench because the dish places the top of the piston even further away from the chamber. I know that there is a thread on here that has an extremely in depth discussion of quench properties on our L motors. I'm sure a little searching could answer your questions What year is your ZX? What are your power goals? What is your budget? Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted November 22, 2008 Author Share Posted November 22, 2008 My car is a '79, and I'm looking (sometime in the future) 350whp... And I'm going to be building this motor as I earn money, I want to build it the right way, and I have no problem driving it N/A for a while until I get this motor built Also, would it be alright for me to build the motor this way, put it in the car with stock components otherwise, and run it like that for a while, while I modify the outer parts of the motor (turbo, injectors, etc.)? Quote Link to comment Share on other sites More sharing options...
Daeron Posted November 22, 2008 Share Posted November 22, 2008 i hear the keys a-jangling already.. Keep searching. you just described the stock turbo motor, except only the P90 and P90a heads were used for turbos, and they have the square port exhaust, so finding a round port turbo header for the P79 might be a chore (or might not, depends on how lucky you get.) Quote Link to comment Share on other sites More sharing options...
cockerstar Posted November 22, 2008 Share Posted November 22, 2008 You can run a square port header on a round port head, but not the other way around Quote Link to comment Share on other sites More sharing options...
ozconnection Posted November 22, 2008 Share Posted November 22, 2008 you just described the stock turbo motor, except only the P90 and P90a heads were used for turbos, and they have the square port exhaust, so finding a round port turbo header for the P79 might be a chore (or might not, depends on how lucky you get.) I don't think it really matters Daeron. I had a factory L20AET that ran the 'Y70' head. That head had round export ports with liners AND it had a turbo manifold that was exactly like the one I had on my other L20 turbo engine which had a square exhaust port 'O5L' head. I don't see how it would matter much on their bigger brothers? Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted November 22, 2008 Author Share Posted November 22, 2008 i hear the keys a-jangling already.. Keep searching. you just described the stock turbo motor, except only the P90 and P90a heads were used for turbos, and they have the square port exhaust, so finding a round port turbo header for the P79 might be a chore (or might not, depends on how lucky you get.) Really? I thought the turbo motors had flat top pistons? Quote Link to comment Share on other sites More sharing options...
blue72 Posted November 22, 2008 Share Posted November 22, 2008 Nope, the turbo F54 motors have a 10.9 cc dish in the pistons, just like the 75-80 N42 motors. It was only the 81-83 F54 N/A motors with the flat tops. The difference between the dished 75-80 pistons and the turbo 81-83 pistons lies in the rings. This was discussed here about a week or two ago. Quote Link to comment Share on other sites More sharing options...
PurePontiacKid Posted November 22, 2008 Author Share Posted November 22, 2008 Nope, the turbo F54 motors have a 10.9 cc dish in the pistons, just like the 75-80 N42 motors. It was only the 81-83 F54 N/A motors with the flat tops.The difference between the dished 75-80 pistons and the turbo 81-83 pistons lies in the rings. This was discussed here about a week or two ago. Oh okay, because the site I found said that they were flattops, so I was under the impression that they were... Thanks for straightening it up for me though! Quote Link to comment Share on other sites More sharing options...
blue72 Posted November 22, 2008 Share Posted November 22, 2008 Here, play around with this: http://www.ozdat.com/ozdatonline/enginedesign/ Lets you try different combination, see compression ratios, get more info, etc... Or go to this page: https://www.msu.edu/~levesqu6/linkindex.htm and scroll down to the Nissan L6 Engine Builder Program. Download that for a program that's executable on your computer. Quote Link to comment Share on other sites More sharing options...
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