DevilZeto Posted January 8, 2006 Share Posted January 8, 2006 Okay this is the deal. Im doing a turbo project on my 77 280z. Right now im using a N42 head which im getting 9:82:1 compresion "using lengine software" but i have a p79 head that im planning on swapping in the near future which gives me 8:52:1.....same as a p90 head????? So whats the difference between them? Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 8, 2006 Share Posted January 8, 2006 I believe the P90 head is for the turbo engines and also promotes better airflow but you should get some other opinions with hard facts Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 8, 2006 Administrators Share Posted January 8, 2006 The P-90 has the SAME chambers and valves as the P-79. The difference between the two are the exhaust ports. The exhaust ports on the P-90 are square like the N-42 head where as the P-79‘s exhaust ports are the Round exhaust ports with liners like the N-47. For a turbo engine, the liners are NOT desirable as they will come apart in short order and as those small parts of broken metal try to pass through the exhaust turbine it will cause problems, at best those broken chunks of exhaust liner will just block the turbo from spinning, or they could end up damaging the turbine… Either way, not good. For a Turbo application, use the P-90. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 8, 2006 Share Posted January 8, 2006 Hey Paul, Why would the exaust liners come apart? is turbo exaust that much hotter? if so couldn't one just cut the liners out. Also is the stock turbo p90 cam different from the stock N/A p79 cam It would be awesome if we could use the P79 for turbo application they're a dime a dozen at the bone yard? Has anyone done it? Matt- Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 8, 2006 Administrators Share Posted January 8, 2006 I’ve seen a few liners on N/A engines that have come apart for one reason or another, including my second L-28 in my BRAAP car. A couple little pieces even fell into the chamber, had to remove the head to get them out and smooth out all the little divots in the chamber roof for those pieces bouncing around in the running engine. I suspect an overly lean condition over long periods caused the liner to run hotter than it was designed to and not to mention all the heat cycles that the liners go through over the 100,000+ miles that are on these cars currently… Any how, I don’t have any first hand experience running a Turbo on a round exhaust port with the liners, but my guess would be that the exhaust runs SO much hotter on a Turbo engine that the liners just wouldn’t live. The liners are sort of “free floating†hen they are cast into the head as and as such, they don’t have any place to allow all that heat to dissipate to, i.e. they aren’t touching the aluminum of the exhaust port itself which would help dissipate the heat. I could be wrong and as you said, it would be nice due the plentiful P-79 heads to use this head. Of course you could always spend the time removing the liners yourself and that would alleviate the worries, though have you ever tried to remove those liners yourself? Boy oh Boy that is a project. I would be curious as well if anyone else has run a turbo on a Round port with liners?.... Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 8, 2006 Share Posted January 8, 2006 Hey Paul, I did some searching and I couldn't find anyone that had been running a P79 head with turbo but I did find a thread that was talking about the performance benifits of the p79 cam over the p90a cam for turbo aplications. I just wanna hear from someone that has or is running a P79 turbo? Anyone? Matt- Quote Link to comment Share on other sites More sharing options...
DevilZeto Posted January 9, 2006 Author Share Posted January 9, 2006 good thing i asked:-D Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted January 9, 2006 Share Posted January 9, 2006 I have an N47 head and a turbo.. and yes it has the exhuast liners... and NO i have not had any issues.. and I am at.. 10,000 miles since the swap.. and i've run 15psi and tracked it many times and have really gotten that puppy HOT... hot enough to throw flames .. I changed the gasket a few days ago.. nice and sturdy to me.. no problems yet Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 9, 2006 Administrators Share Posted January 9, 2006 I have an N47 head and a turbo.. and yes it has the exhuast liners... and NO i have not had any issues.. and I am at.. 10' date='000 miles since the swap.. and i've run 15psi and tracked it many times and have really gotten that puppy HOT... hot enough to throw flames .. I changed the gasket a few days ago.. nice and sturdy to me.. no problems yet[/quote'] Nice to read one persons experience running a turbo charged round exhaust head with the liners. Glad to hear that your liners are holding just fine thus far. With you’re your MSnS-E, are you running the Distributor-LESS EDIS-6? What V. are running, 2.2 or 3.0? I’m currently installing the MSnS-E V-3.0 with EDIS, (wasted spark distributor-LESS ign), for my F-prepared SOLO-II car and would like to see how others are doing their EDIS-6 installs on their Z cars. My MS controller just arrived from RS Autosports yesterday, quality is FIRST rate through out. I’m ordering another MS controller from them in the next few weeks for another L-28 Z project and then will order another MS controller from RS Autosports for my V-8 Z project, probably in the spring or summer of ‘06, and of course, ALL of these MS projects are going distributor-LESS ign, including the V-8! I just finished my crank trigger set up today, (this link takes you to the details and pics of the crank trigger install, as of this AM. I’ll update Monday afternoon with even more pics… http://forums.hybridz.org/showthread.php?t=103781 ). Keep us posted on how the liners hold up with boost… Quote Link to comment Share on other sites More sharing options...
AdrianZ Posted January 9, 2006 Share Posted January 9, 2006 what if you port and polish the head. will that take off this evil linner? Quote Link to comment Share on other sites More sharing options...
pjo046 Posted January 9, 2006 Share Posted January 9, 2006 http://www.geocities.com/zgarage2001/head.html Quote Link to comment Share on other sites More sharing options...
Yokohama Posted January 12, 2006 Share Posted January 12, 2006 You can remove the liners with no real problem. Some people do it on the N/A and others leave them in. The trick with the N/A engine is to blend in the base of the liner into the valve seat. The liner in the N/A engine will help the exhaust gas make the turn in the port instead of slamming into the top of the port wall. It will actually make power over just taking them out. See, the liners are not so evil after-all! With the turbo, it could be a good thing if you take them out and combine them with a turbo tubular header made to match the port. Interesting idea, but I have never done this (yet). Quote Link to comment Share on other sites More sharing options...
TimZ Posted January 12, 2006 Share Posted January 12, 2006 Any how, I don’t have any first hand experience running a Turbo on a round exhaust port with the liners, but my guess would be that the exhaust runs SO much hotter on a Turbo engine that the liners just wouldn’t live. If the engine is allowed to run lean, or with too much retard I could see this, but I don't think a properly tuned turbo engine should see exhaust temps that are appreciably different from N/A. Granted, it's probably easier to get yourself into lean conditions or not have enough timing while tuning a turbo motor. I gererally run ~1450F at full boost. Isn't that about what N/A engines target? Quote Link to comment Share on other sites More sharing options...
Pyro Posted January 13, 2006 Share Posted January 13, 2006 A friend of mine runs a P79 with turbo pistons and a stock T3 at 15 psi for a few years now on his daily driver (his only car). He hasn't had any liner issues. I have seen flow data showing the liners actually help flow. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.