Mycarispurty Posted November 30, 2012 Share Posted November 30, 2012 I have the benefit of having 93 octane gas here in Chattanooga, so that's a plus towards the goal I suppose. I'm picking up a 240Z with the E88 head (2/73 model) this weekend and the guy says when his friend sold it to him, he was told the motor was knocking. I'm going to try and diagnose that first when I get it home. If it turns out to be a rod knock or something like that, I have found a nice clean rebuilt F54 bottom end with the flat tops. My plan is to purchase that bottom end and slap on the E88 head unless I find a clean N42. Anywho, I've seen where people suggest getting a cam with a longer exhaust duration I think it was to help with the higher compression, and I know I can dial back the timing to help with it too, but I don't want to turn it into a slug just to make it road ready. Fortunately, its just a toy as I have a 300ZXTT I drive around as a daily car so it's not a problem I have to sort out immediately. The car does have Redline Weber DGVs so it does already have better carburetors, hell it may even have a cam in the head since the guy he bought it from already hotrodded the intake, suspension, wheels, and exhaust. Just trying to get some information beforehand so I can try and compile a shopping list. Quote Link to comment Share on other sites More sharing options...
Josh280z Posted November 30, 2012 Share Posted November 30, 2012 There are multiple threads regarding high compression... Do you know what detonation is? Detonation is what happens when the fuel doesn't get ignited at the right time. Maybe, the longer exhaust duration would help, but that is throwing away power and money. I've heard of people using a hotter spark (i.e. MSD ignition 6AL box) to make sure that all of your fuel is burnt at the right time. Then again, maybe the higher octane in Tennessee will be the answer to your problem. Also, running a richer mixture might help but that make your engine dirty. Hell, I've asked many questions; posted, searched and PM'ed until my questions were answered and I probably annoyed the hell out of some people with everything. Not trying to sound rude but I've gone through similar stuff http://forums.hybridz.org/index.php/topic/105053-high-compression-questions/ Quote Link to comment Share on other sites More sharing options...
Mycarispurty Posted November 30, 2012 Author Share Posted November 30, 2012 I know what detonation is. It's been a long time since I've been around the early Z community, never looked into a high compression build because I always wanted to SBC or turbo swap a Z...now I'm at the point that I don't want to do any of that extra work, I'd rather just have a peppy Z without having to wire in an EFI system. Just figured someone might recommend one of the MSA cams or a specific regrind they liked that worked well. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 30, 2012 Share Posted November 30, 2012 The 73 E88 is a boat anchor. There is nothing good about that head. It's an open chamber NOx reduction design. I'd suggest you find a P79 or a P90 and run that, and maybe shave it if you don't want 8:1 compression. I ran a .020 over F54 with dished pistons with E31 and it ran fine on 89 (I think it would have run fine on 87 too). Then I rebuilt it with flat tops, compression was about ~11:1 with the different valves that I had installed, and it pinged like crazy with the .490/280 cam that I had. I mixed race gas with pump to figure out what it needed to stop pinging, turns out it was 95 or 96 octane. If I had to do it again, I'd much rather run an engine at 8.x:1 or shave it for 9:1 or 9.5:1 and then run it on pump gas. Especially if it is a daily driver. There is more power in being able to run the timing at the right spot than there is in the extra point of compression, plus you won't be driving down the road wondering "Did I just hear a ping?" all the time. FWIW, I'd ditch the DGVs too and pick up some early roundtop SUs. Quote Link to comment Share on other sites More sharing options...
madkaw Posted November 30, 2012 Share Posted November 30, 2012 I'm with Jon on this. Search and you won't find much good being said about THAT year e-88 head. Now if you find an early e-88, like late 71, then you are in a different game. I wouldn't waste the effort and lot's of money to get that 73 head to work, find something else. Also, nothing against Schneider cams(MSA), I run one with good results, but the cheaper -maybe better route is to get a stock reground. Do some more research Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 30, 2012 Share Posted November 30, 2012 There is absolutely nothing at all wrong with that head. It has the same ports as the later N42, already has the larger exhaust valve, and the only difference between that chamber and an N42 is the spark plug boss. One benifit of that head is that it's already as unshrouded as you can get, for an unmodified head. Also...everyone hates on them, so they're cheap! If you are looking to control detonation with a cam, then run a longer exhaust duration, longer intake duration, and LOOK AT THE INTAKE VALVE CLOSING TIMING. Close the valve a little late and it'll bleed compression off at lower RPM. It'll actually help cylinder filling at higher RPM, but the main benifit in this case is lower dynamic compression. This exact mechanic is why I can run Kentucky 87 octane on a dished bottom end with an open-chamber N42 that has been shaved to provide 9.7:1 compression, and STILL run a full 36 degrees of timing with no tendency to ping or knock. Just set the valve closing event to bleed off some of that compression from idle to about 3500 RPM, and you can avoid a LOT of detonation. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 30, 2012 Share Posted November 30, 2012 The original question is so vague that its unanswerable. Quote Link to comment Share on other sites More sharing options...
Leon Posted November 30, 2012 Share Posted November 30, 2012 I would not call the Weber DGVs "better carburetors". Quote Link to comment Share on other sites More sharing options...
inline6 Posted December 5, 2012 Share Posted December 5, 2012 (edited) I ran an F54/E88 (not the early one) combo for several years. I believe compression ratio worked out to about 10:1. I also ran a "Euro" single point distributor. I think my initial advance was 17 degrees. I had the vacuum advance hooked up and it was functional. Full advance was around 36 degrees by something like 3000 RPM. The head had mild port work done (intakes matched to stock intake gasket port diameter and only modified about 1" in from the intake manifold surface). Exhausts were ported only in the transition from the bowl to the port runner - again mildly. I ran the stock cam, stock exhaust valve size and 1 mm larger intakes with L28 valve seats installed... 93 octane was readily available and I had no noticeable knocking... unless I did something like put it in 4th gear at 20 miles per hour and press the gas peddle to the floor. Then I could hear some faint knocking. So, I list all that because maybe one or a combo of those things helped reduce knocking... I don't know. Seems some people have real bad problems with detonation on certain L series heads. I certainly did not and I didn't have to retard the timing or anything either. That engine put down 151 at the rear wheels (with early 4 bolt SU carbs) when I had it dyno'ed about 3 years ago. Edited December 5, 2012 by inline6 Quote Link to comment Share on other sites More sharing options...
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