olie05 Posted January 5, 2005 Share Posted January 5, 2005 Hello, Mike (on3go) offered to let me use his turbo when he got another one for his blue z... This got me thinking about the possibilities of a "high cr" turbo engine. (I assume this is high for a turbo engine as I am only supposed to use premium gas as it is) A turbo on this engine would have no lag... but the problem is detonation. I want to avoid it at all costs. The way to do this would be through engine management and intercooling (I think) Would it be easier to convert to megasquirt and the electronic distributor, or could I get by with swapping to the turbo FI? What type of intercooler would I need to keep this thing under control? What psi's would I be looking at to run? I need to run this thing on 93 octane!!! very important!!! Please note that this is in the planning stage and I realy don't plan on turboing my car for a while... Also note that I am currently running an N42 block and head. I could easily switch to a p90 head for an 8.7:1 cr but I would lose the whole point of a high cr turbo engine. Thanks! -Oliver Quote Link to comment Share on other sites More sharing options...
GrayZee Posted January 5, 2005 Share Posted January 5, 2005 Anything can be done I guess, but it does not sound like a very good idea to me. True, high compression can be good for performance but basically the lower your CR the higher the boost you can run. I think the RB26 has 9.6CR?? and that is VERY high for a turbo engine, but also consider that a RB26 has alot more modern design and no doubt Nissan learned a thing or two in 20+ years of engine building. To run 10.03CR on a turbo'd L engine that was designed back in the 60's you would likely need to run some crazy kind of high octane fuel mixture, a very good intercooler, water injection, have awesome fuel/spark tuning and still end up having to run fairly modest boost. I think you would get much better results from turbo-ing a low CR engine and running really high boost (probably alot more stable too!) That's my opinion, we shall see if others agree... Quote Link to comment Share on other sites More sharing options...
motorsci Posted January 5, 2005 Share Posted January 5, 2005 A high compresion turbo is not a bad Idea. 7psi to 10psi would be the most on a 10 :1 the p90 head would produce more power it,s a better head and increses the volume of the cylender. so If the volume is greater more fuel and air can be packed into the cylender and more hp. meggasqurit for the money is the best deal your biggest gain will be form an aftermarket adjustable fule /ignition system. good luck there 8.7 to one is a verry good set up fore a turbo 8.5 is suposed to be ideal Quote Link to comment Share on other sites More sharing options...
Drax240z Posted January 5, 2005 Share Posted January 5, 2005 I hate to make such a blanket statement, but you'll never get 10psi out of a 10:1CR L-series with 93 pump gas. Not for long anyway. The L-series head isn't anywhere near as efficient as a modern head design, and once you start pushing over the 10:1CR area naturally aspirated you're going to be running into problems on pump gas. Throwing a turbo and any kind of boost on top of that will compound the problem. Quote Link to comment Share on other sites More sharing options...
Thumper Posted January 5, 2005 Share Posted January 5, 2005 I second drax240z. Sorry olie but i don't think you can run over 10:1 and have anything over 3psi. You could run the 8.7:1 comp ratio and probably 10-15psi safely. Don't forget stock turbo's comp ration is 7.38:1 and na's are 8.52:1. That would be a sweet high 12, low 13 second 280z then. Oh let me know when you want to come over tom night so we can put your rear end in. L8r Quote Link to comment Share on other sites More sharing options...
olie05 Posted January 5, 2005 Author Share Posted January 5, 2005 Well I guess I won't try this turbo thing out on this engine without lowering the CR first. I thought there might be an intercooler and low boost set up that might have worked but I'm just going to stick with NA for now. Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 6, 2005 Share Posted January 6, 2005 I think the RB26 has 9.6CR?? and that is VERY high for a turbo engine, They're 8.5. I also don't think you'll get 10 psi out of it. Compression doesn't have that much to do with lag either. Atleast not enough to merit a high CR. If you can accept a low boost set up (5 psi) and it's free to borrow I would run it. Using a NA ecu that doen't retard timing or add fuel under boost would also be a problem. Quote Link to comment Share on other sites More sharing options...
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