AydinZ71 Posted March 28, 2022 Share Posted March 28, 2022 I would not worry too much about a turbo cam. Unless you are working with an engine builder with a lot of experience on the matter, I would stick with the stock cam and focus more on the quality/capacity of your intercooler, managing engine heat, turbo efficiency, etc. Not to say there is zero value is working your head for a turbo built, its just much further down the list. Quote Link to comment Share on other sites More sharing options...
lowrider Posted March 28, 2022 Share Posted March 28, 2022 Those that are disbelieving that the exhaust liners break and come out, I have experienced it personally. I originally started my turbo journey with a stock F54 flat top bottom end and a P79 head coupled with a Z31 T3 Turbo. It ran well for quite a while but ultimately I broke the rings/ringlands due to inexperience tuning. However before I broke the pistons, I had one exhaust liner break apart and lodge itself in the exhaust wheel of the turbo. Thankfully it was at low speeds and didn't wreck the turbo, it just wedged itself into the fins of the turbine and kept it from spinning. I pulled the single liner and re-assembled everything (I was broke and in college lol); the motor lasted for a year or so after that before the pistons/rings gave up the ghost. I swapped to a stock N42/P90 combo not long afterwards and have had that combo (multiple bottom ends) in various iterations of the setup over the past 10 or so years. I can say that I miss the off boost response of the higher compression flat top combo though. Quote Link to comment Share on other sites More sharing options...
rossman Posted March 28, 2022 Share Posted March 28, 2022 (edited) Thanks for he feedback, @lowrider! t's good to know! I just happened to search ebay and found a P90a for sale and bought it. The price seemed high but like others have experienced here, they are becoming difficult to find. Fingers crossed that it's not warped. It will need solid lifters too. Edited March 28, 2022 by rossman Quote Link to comment Share on other sites More sharing options...
rturbo 930 Posted March 30, 2022 Share Posted March 30, 2022 On 3/25/2022 at 6:39 AM, madkaw said: I think the liner issue for a turbo is fairly isolated. I have noted that there is a difference in casting quality from early liner heads and later ones. Look at a early n47 compared to a MN 47 or p79 . I have personally removed the liners from a MN47 and I see no way they would come out unless they disintegrated . They are extremely hard to remove . The later years have better casting supports for the liners to sit on and much better casting in general. I'm assuming that head was for an NA build, doesn't removing the liners ruin the flow of the head? I have an N47 with liners removed, I was under the assumption it was junk based on research, and was planning to replace it with the N42 I have... eventually. Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 30, 2022 Share Posted March 30, 2022 9 hours ago, rturbo 930 said: I'm assuming that head was for an NA build, doesn't removing the liners ruin the flow of the head? I have an N47 with liners removed, I was under the assumption it was junk based on research, and was planning to replace it with the N42 I have... eventually. There’s a guy running a MN47 without liners with good success (200+ HP L28) I’ve showed my MN without liners to a couple of machinist and they thought the flow wouldn’t be that affected . It does leave a big gap under the seat which I would like to fill , but that would be almost impossible due to location. The rest of the port can be smoothed out . It does leave a massive port at almost 38mm at the port exit from the head . I think the MN 47 is best left NA mostly because of its small chamber Quote Link to comment Share on other sites More sharing options...
DATZ Posted May 5, 2022 Share Posted May 5, 2022 On 3/23/2022 at 12:21 PM, NewZed said: Dished pistons never have any "real" "quench". The turbo engines aren't quench chambers. "Quench" or "squish" is a word that is usually undefined and unmeasurable. Usually determined by eyeball. There's a theory, combustion gases squirting and swirling around, piston tops being cooled, etc., but I don't think that you'll find anything anywhere where anyone has shown that they compared "quench" to non-quench in an L engine and saw an effect. Most of the discussions center around the old "engineers did it it must mean something". No offense to anyone intended here. If someone has data that would be cool. While you're researching, look for stuff on the exhaust port liners and turbos. The only Z heads that have any quench (“squish”) are the P79/P90/p90a. The E31, E88, N42, N47 have Zero quench regardless of the piston. If quench isn’t perfect, you don’t want it. Quote Link to comment Share on other sites More sharing options...
mutantZ Posted May 6, 2022 Share Posted May 6, 2022 If you are looking for a p90a there is one on ebay right now https://www.ebay.com/itm/144492508682?hash=item21a46cb60a:g:lpAAAOSwye1iTzCE Quote Link to comment Share on other sites More sharing options...
Zellthetunerr Posted June 13, 2022 Author Share Posted June 13, 2022 @AydinZ71 @rossman @madkaw thank you for your inputs but I have the head all apart at the moment. Its a pain removing them but as I've worked more and more I getting better and faster at removing them. Challenges come and go. I just gotta keep pushing if I wanna do it. And about the cam I just head that if you're running 11-14+ lbs. of boost that it would be recommended to actually change it and also get a new rocker/valvetrain while I'm at it. Like a kit at Schneider or MSA. But I guess not. I will take it to a machine shop to get all the work that I can't do in the garage without special equipment. sorry for the late reply 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.