Guest flyZ Posted January 7, 2005 Share Posted January 7, 2005 So now everyone put your figures here! With N/A and with turbo L6 engines how high compressions you have? Which head did you use? And how high octane gas do you use? It would be nice to hear what kind of experiments you have made with this engine.. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 7, 2005 Share Posted January 7, 2005 I run ~11:1 and I have my chambers polished with no sharp edges. E31/L28 combo 490/280 cam. I need 95 octane to keep from pinging and get a full 35º advance. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted January 7, 2005 Share Posted January 7, 2005 I'm at 11.5 to 1 E88 ported polished, hardend valves & seats, bronze guides L28 block (I forget wich one) 11.5-1 forged pistons 240 rods I can run on 92 but as you may know if you've followed my recent threads I run a very cool engine(maybe too cool). Isk Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted January 7, 2005 Share Posted January 7, 2005 N42 head, 11:1 N/A, 93oct pump gas. That's with a fairly big cam, btw (~305deg/.550"). Quote Link to comment Share on other sites More sharing options...
preith Posted January 7, 2005 Share Posted January 7, 2005 I have an L28/N42 .040 over, JE domed w/7.5 cc's displacement, unshrouded valves, chambers 45.5cc's, which calculates to just under 12:1. I was told once it's around 14:1, or a very aggressive dome, the flame pattern becomes very poor. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted January 7, 2005 Share Posted January 7, 2005 Preith, what octane are you running? I'm 40mm over too. Isk Quote Link to comment Share on other sites More sharing options...
preith Posted January 7, 2005 Share Posted January 7, 2005 Preith' date=' what octane are you running? I'm 40mm over too. Isk[/quote'] I've never tried anything less than 110 leaded. I had originally thought the compression was higher (didn't know the actual piston displacement). $4 per gallon last time I bought it. But I've also been running a pretty good amount of advance, around 40, and havent' experimented too much with that yet either. Quote Link to comment Share on other sites More sharing options...
Forrest Posted January 7, 2005 Share Posted January 7, 2005 Preith' date=' what octane are you running? I'm 40mm over too. Isk[/quote'] 40MM over!? Now THAT'S an overbore! Quote Link to comment Share on other sites More sharing options...
johnc Posted January 8, 2005 Share Posted January 8, 2005 13.6 to 1. Sunoco Supreme - 112 (R+M/2). Quote Link to comment Share on other sites More sharing options...
DrSideways Posted January 9, 2005 Share Posted January 9, 2005 Right now mine is at 14.2/1. We also use the Sunoco 112 leaded. Another unique deal on this current motor is a 140mm CtoC rod. That puts to rod stroke ratio close to what a 240 would be. This is used to cut down on the scuffing on the bore sides. The head is a E31 with a Gerolamy type porting job. I agree with the dome not letting the flame travel as good across the chamber. However the jetting has been easier with this combo than any other so far. It pulls like a mother right up to 7300 or so. If in a tight spot it can run higher. Generally speaking though I shift to not let it hang out in the 7500-7800 range too much. The harmonics are such that it is better on the crank to have an 8500 rpm redline and cruise through the high sevens than to rev it to into the high sevens and let it hang there at the end of a straight. I might even short shift into the next gear to let it have more torque time for additional speed. This is where the extra compression helps out. I guess it $$ were no object it would be nice to do an 85mm stroker with another billet crank and dry sump it. That would give the good compression and a flat top piston. That should pull a G-nose IMSA body up the track pretty well. Alan Quote Link to comment Share on other sites More sharing options...
GrayZee Posted January 9, 2005 Share Posted January 9, 2005 I haven't seen anybody post their turbocharged CR's yet.. Is there a formula somewhere that will tell you what your CR would be equivalent to given the PSI you are running? Oh wait, I found one.. http://www.autocomponenti.com/boosted_tech/boosted_tech.htm I guess that means I'm running somewhere around the neighborhood of 9:1 on 91 octane with no intercooler.. Looks like there's room for improvment.. LOL Maybe I should just turn up the boost a bit and run 94 octane.. Hmm... Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted January 9, 2005 Share Posted January 9, 2005 40MM over!? Now THAT'S an overbore! Oops. .040 or 1mm Yeah 40mm what is that 1.5" Oh my head is a B.C. Gerolamy as well. Isk Quote Link to comment Share on other sites More sharing options...
olie05 Posted January 10, 2005 Share Posted January 10, 2005 I'm running 10.03:1 on my setup... I have an N42 block (bored .040" over) and N42 head, the head is milled for flatness so that must raise the cr a little too, and I used flat top pistons to get the cr up. I've never run anything below 93 octane on this setup... (almost did once, but I didn't actualy do it). On that turbo cr stuff, I heard on this board a while back that you can't compare cr's of turbo cars and N/A cars, because once the turbo kicks in you're not dealing with static compression ratio, and if you have an intercooler the possibilities are much larger, because you can cram more pressure in without having as much detonation as an N/A engine would with the same amount of pressure... (or something like that) -Oliver Quote Link to comment Share on other sites More sharing options...
GrayZee Posted January 10, 2005 Share Posted January 10, 2005 On that turbo cr stuff' date=' I heard on this board a while back that you can't compare cr's of turbo cars and N/A cars, because once the turbo kicks in you're not dealing with static compression ratio, and if you have an intercooler the possibilities are much larger, because you can cram more pressure in without having as much detonation as an N/A engine would with the same amount of pressure... (or something like that) -Oliver[/quote'] Oh no doubt it's like comparing apples to oranges, I'd just like to see what turbo's compared with other turbos. (or superchargers, whatever) Like what their initial CR is, along with how much boost, intercooler, water injection, what sort of ecu, ect. Quote Link to comment Share on other sites More sharing options...
Guest Magic Posted January 11, 2005 Share Posted January 11, 2005 8.4:1 cr port matched polished P90 head L28 NA block and cam. 98 Octane T3/T4 turbo Standard inlet and exhaust manifold 57mm Throttle body. Custom FMIC 7psi today - tuning for 12psi or above tomorrow (literally) just finished running the motor in. Autronic programable fuel ignition. I havent tried to put any timing into the boost part of the table yet as I have been running it in. But it still goes great. Quote Link to comment Share on other sites More sharing options...
Mack Posted January 11, 2005 Share Posted January 11, 2005 grrr, bout the 3rd time Ive answered one of these threads in as many weeks. I am running about 11:1 compression. I have an F54 flat top block with a maxima N47 head and a 260Z "c" stamp camshaft. I am running a felpro headgasket, which is a little thinner than a nissan unit. with the excellent quench characteristics of the head and the slimmer gasket, I CAN run 89 octane, but I usually stick to the 91 stuff. My car is my daily driver, and I deliver pizzas with it. oh yeah, I run about 15 degrees initial and whatever the total would be with an '82 distributor. Mack Quote Link to comment Share on other sites More sharing options...
Guest 260ondubs Posted January 21, 2005 Share Posted January 21, 2005 My motor is still being built.... but.... I am using: F54 block with dished pistons etc.... E88 head fully prepped for injection. Slight machining 1.5mm metal head shim. Aiming for CR of 7.8:1 Haltech E6X L20ET/L28E camshaft (haven't decided yet) Suggestions? Modified hybrid T3 at 18psi 98 octane unleaded Should be safe at that boost level and such up to about 6100 rpm. I hope. Quote Link to comment Share on other sites More sharing options...
jeffp Posted January 23, 2005 Share Posted January 23, 2005 Well according to the chart, @ 8.5:1 I am up around 15.5:1 under boost. Needless to say I have to run race fuel for that compression. I can get by on C12 I think it is 108 octane. 92 octane, I can run up to about 11psi of boost. Quote Link to comment Share on other sites More sharing options...
ww Posted January 23, 2005 Share Posted January 23, 2005 F54 w/ heavily massaged N42 & IC 15 PSI on 91 pump gas 25 PSI on 108 octane P90 going under the knife... Quote Link to comment Share on other sites More sharing options...
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