hartsel Posted August 6, 2011 Share Posted August 6, 2011 hey dudes, just signed up for this site today. everytime i google search something for the 280z the websites' forums usually pop up so i figured i would give it a try. so heres the deal. i live in kansas and my ability to obtain e85 fuel is good. we all know, or at least i know, that this fuel when adjusted so that you use 30 percent more, has an octane rating of around 104. which is why im starting this topic. i dont really want to turbo my z, i want to make this thing a high compression street machine by milling my head down. the biggest problem i run into with this goal is that not alot of people can do high compression mods due to the lack of high octane fuels. i just went and checked and my engine is made up of the n42 head, and n42 block. lets assume the pistons are nothing more than one of the stock choices and the head has not been milled except if anyone wanted to make sure it was nice n flat for a rebuild. i just want to know how much can be taken off the head before my valve will start hitting my pistons, also assuming the cam is stock. and whats the most compression i could get this way. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 6, 2011 Share Posted August 6, 2011 The L Series engine forum is difficult to find for some reason but here's a link - http://forums.hybridz.org/index.php/forum/90-l-series/ Quote Link to comment Share on other sites More sharing options...
19762802+2 Posted August 7, 2011 Share Posted August 7, 2011 (edited) There are a few really good sticky's in the FAQ forum about heads, Like Braap would say a P79, or P90 with Flat top pistions (your N42 block has Dished pistons) would be much better for a high comp street engine because of the better quench, You also don't need to worry about your valves hitting you need to worry about having too much compression, I think maybe a 9.5.1 comp ratio maybe a bit higher, run that octance and advance your timing as much as you can without pinging and you will be able to do just fine. Also you want a good cam for your set up too, And don't forget that a stock ECU can't really handle a bigger cam so if you want to use a different cam you will have to run carbs or go Aftermarket EFI Edited August 7, 2011 by 19762802+2 Quote Link to comment Share on other sites More sharing options...
Lazeum Posted August 7, 2011 Share Posted August 7, 2011 (edited) I agree with what you just said except for one comment: I think maybe a 9.5.1 comp ratio maybe a bit higher, run that octance and advance your timing as much as you can without pinging and you will be able to do just fine. The limit would be MBT (minimum best timing) not "as much timing as you can". Most likely with high comp L-engine you will ping and never meet MBT but it would mean your engine is not optimized to get the best of it (for NA application). That's why Braap advices to not go further than a limit (for instance around 9.5 with P79/90 head AND correct cams as you've said ) Edited August 7, 2011 by Lazeum Quote Link to comment Share on other sites More sharing options...
hartsel Posted August 16, 2011 Author Share Posted August 16, 2011 so lets assume i order one of these p90 heads refurbished from somewhere like ebay, is this reliable. or should i just find someones used one in the classafieds. ? Quote Link to comment Share on other sites More sharing options...
hartsel Posted September 2, 2011 Author Share Posted September 2, 2011 i read an article where a z vet took a p90 head and had it milled 80mil then adjusted the cam towers and springs with 80mil of spacers. and put in some 76 or so years valves cause they were 80 mil longer. with this and flat tops he was only getting 10.05 to 1. how do the guys build engines that have 12-1. what kind of parts does this take. Quote Link to comment Share on other sites More sharing options...
copperdatsun76 Posted September 2, 2011 Share Posted September 2, 2011 if you want a 12 to 1 CR you will have to run e85 or race gas, there is no way around it really Quote Link to comment Share on other sites More sharing options...
ZIPPY Posted October 29, 2011 Share Posted October 29, 2011 Hey there, I dont post a lot on here but this thread caught my eye for some reason. You want to run a high compression NA engine, go for it. Anyone who tells you not to go above 9.5:1 compression has no experience at all with a a high comp street car. So many people just repeat what they read somewhere else on the forum from someone who is repeating another post from someone who is guessing... I have been running about 12.4:1 on California 91 octane in my car for almost two years now. 2.8L and SU carbs making over 200hp on the wheels on pump gas. People always tell me I'm full of $h!t until they race me, lol. I use a P79 head, flat top pistons and a schneider cam. Granted everythign had be extremely modified but you can proabably get almost that much power just by swapping to flattops and a Maxima N47 head (11.3:1). Or use a P series and do the 0.080" shave thing(mid 10's?). If you have easy access to e85 then by all means do that, and go even higher on the compression. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 30, 2011 Share Posted October 30, 2011 Capitalization and punctuation are required when posting on this site. (Directed at hartsel and copperdatsun76) Read the rules if you haven't, it will save you some agony here in the future. Quote Link to comment Share on other sites More sharing options...
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