BRAAP

Eeewww…. Braaparappa?!?!? (in my best Dr. Evil imitation…) “Gold Member, that’s not something one dude should say to another dude. Yeah, a bit freaky.. “

OTM, you are the BOMB baby… Ala bombarama…

Fair enough… Yeup, quite familiar with textured ports. No black magic there… We leave the intake ports in the head with either a sanding wrap finish or bead blast finish. As for the L-series head, I agree. We have to work with what we have and overcome as many of the shortcomings that the L-series has in a cost effective manner that fits within the customers budget and performance goals. That is a delicate juggling act for sure… As for who is Rusch Motorsports? Just do a search here on Hybrid for “BRAAP” and read some of the tech articles I’ve written and take a look at a few of the Datsun L-series cylinder heads/engines we’ve built... Here is a sample of what we do… This P-90 head ran on the PINKS Z, 5 angle valve seat work, extensive valve unshrouding, and the list goes on and on. In the PINKS section of this forum you’ll find all the details of this build up, (that is if it is still accessible, haven’t checked in a long time). A very custom high compression welded chamber N-42 for a Hybrid members road race car. A complete custom L-22 hybrid engine build for Mark Warner. Ron Tyler and myself scratch built the intake as well. Currently, this is the icing on my engine building career. This engine we built, machined, and Dyno tuned at Sunset Engine Development for Justin Boice of Boice Jet. This 540 CID BBC Twin Turbo, multi port EFI, water to air intercooled, white water endurance Jet Boat race engine produced a whopping 1168 HP at 5800 RPM on the Dyno with 12 psi of boost on AV gas and 10:1 compression. Justin went on to set more than a few speed/time records around the world with this engine, mostly in the western US and New Zealand. here is shot of the engine running on the dyno churning out 1168 HP… Valley shot during the build up… The boat it powered on course, Rogue River, southern Oregon. Ok, now lets get this thread back on track discussing custom L-6 Fuel injection intakes… BRAAP… OUT!

Yes, Bubbles points do have some validity, technically speaking, but “not” to the extreme that he was boasting, same goes for “lt1will620”’s post. C’mon guys. Offering forth advice or ideas for sake of conversation or for others to ponder and possibly tryout and learn from is great. But to make blatant statements of “this” is right or wrong with no actual professional background in that field, you are just asking to get shut down from those that do have actual “practical” knowledge and experience about engine design, tuning and power development, especially with a particular engine such as the L-series. Lets keep this in perspective folks. We are dealing with a 2 valve Datsun engine, not an F-1, NASCAR, or Indy car power plant here. “lt1will620” mentioned O-2’s in the primaries of 1 fast Z’s header claiming a rich mixture in the center cylinders?! In my “professional” opinion, that ASSumption that Bryans intake would yield enough fuel mixture differential between ANY or ALL cylinders to make a measurable difference on the dyno is bogus. These are DATSUN street engines guys! If that was an F-1 engine or NASCAR engine, then yes, that would be seen and dealt with as important. These are Datsun engines that are NOT making 3-5 HP per cubic inch guys! If you are going to pick apart his intake manifold design as if it were to be used on an F-1 or NASCAR engine, then why aren’t you picking apart the cylinder head that Nissan cast in the first place? How about the fact that the cam is “over” the rockers and not “under” the rockers in an effort to shorten the overall height of the L-series engine, (similar to the NAPS-Z and VG-30E), which would also slightly lower the engine CG? I’m sure that would stir up a huge debate… Remember, these are DATSUNs, not INDY or IMSA Group-C. In defense of “1 fast Z”, Bryans “intake” is NOT holding his engine back from making stellar power! The cylinder head by design has more issues than his intake does, PERIOD!!!!! You guys are missing the forest for the trees here. Sure his runners aren’t EXACTLY equal length, but are they really so far out of proportion from one another that there could actually be a measurable difference worth squabbling over? I’d bet there’s not more than 5 HP difference over a comparable equal length intake design, more like 1-2 HP using that same cam, exhaust etc, and that is barring any other variables. The angularity of the center cylinder runners also aren’t quite ideal, but is it going to cost even 5 HP? I don’t think so. Even if it was woth5 HP. IS that going to drop half second off his ET when he is already running high 12’s? NOT!!!! Are we building a DATSUN L-series or a Top Fuel drag car? Keep it in perspective…. Bubbles used Norms car as an example previously, so lets use it again, (no offense Norm, you know how I feel about your car, DAMN FAST!!! I’m just using it to get a point across.) I urge you guys to take a close long look at the runners of the SU carbureted intake manifold. Not only do these SU manifolds have much more substantial direction changes in the runners vs Byans, (cylinders 3 and 4 in particular), look at how much difference in there is in length of the SU runners percentage wise? Somewhere between 50-100% “difference” between cylinders 3-4 and the 1-2-5-6 runners. Even with that drastic difference, Norms car works rather well doesn’t it? Lets go a little deeper in to this, shall we… Being as the fuel is also flowing through those SU runners, not just air, (carbureted intakes are considered to be “wet” intakes), and remember, fuel is heavier than air, there is more chance for differing Air Fuel Ratios from cylinder to cylinder due the sharp path changes as compared with “1 fast Z”’s intake, (in particular cylinders 3-4 vs cylinders 1-2-5-6). The fuel in the air stream of the carbureted engine will want to separate from the air as it makes those hard sharp direction changes. So as for “1 fast Z” mixtures from cylinder to cylinder being allegedly different, even the AFRS were, it is nowhere as drastic as ANY dual SU carbed Z car would be, even Norms. The age and quality of “1 fast Z’s” fuel injectors will have WAY more influence on the mixture from cylinder to cylinder than what his intake design has on the AFR. Lets quite squabbling and get this thread back on topic with some actual real world info, not argue over things that really don’t benefit DATSUN engines. Paul

Hmmm. You didn’t search much here on Hybrid did you?... Here is a little help with LOTS of details and pics answering the questions you asked… Extensive EDIS and L-6 info… http://forums.hybridz.org/showthread.php?t=103781 The EDIS Test Bench.. http://www.msextra.com/viewtopic.php?t=14920 DIS ignition and EDIS http://forums.hybridz.org/showthread.php?p=666236 My personal up and running EDIS project… http://www.msruns.com/viewtopic.php?t=15436 Coil packs… http://forums.hybridz.org/showthread.php?t=115481 Hope that helps… Paul

Are you having troubles bubbles? Trouble opening your minds eye that is? Are you a professional engine builder/tuner, or a magazine engine builder tuner, or have you just read a lot of magazine articles and think you know it all in terms of HIGH PERFORMANCE? I am normally very passive when others get closed minded on the forum but your posts are not just pushing my buttons, but pounding on them… You talk as if you are an expert engine builder/tuner. The rest of us are only seeing one 13 second time slip from you to back up your wealth of knowledge. You can’t be telling us that because you have a 13 second time slip, you are now some sort of performance guru, are you? You do realize that when you criticized “1 fast Z”’s intake, you were in fact criticizing an actual professional engine builder/tuner that “does” build some successfully quick L-series cars right? How bout instead of just telling professional engine builders/tuners how they should do things different to go faster, why don’t you put your key board away, go out into your garage/shop and actually “prove” to us that you know what you are talking about and build an engine that will impress us all to the level YOU feel is impressive? Sheesh….

Bubbles, Are you by chance a professional engine builder?

Okie dokie… Rusch Motorsports is on board, of course the fine print/details need to be worked out, but suffice to say, We would be glad to offer our services, for either or both projects, Especially L-6 cylinder head work… You can post me directly at braapZ350@hotmail.com or ruschmotorsports@hotmail.com Paul

As an engine builder/machinist myself, I’m not up for slandering another shops work. In looking at the pics of your bearings, something definitely went wrong, whether it was the fault of the shop that built the engine or not. The thrust bearing, (middle bearing), is very suspicious compared to the others for sure, and the shop that built the engine should at least be wiling to look at and evaluate the engine as a whole before blaming the customer. If this was an oil supply issue, all the bearings, especially the rod bearings, would show signs, but the center main bearing to me indicates a clearance issue. Of course, I’m just speculating based on one picture without seeing the entire engine in person. Your experience is not the norm and I am sorry this happened to you. We hope your next engine is everything you hope it to be. Paul Ruschman Rusch Motorsports

Typhoone, Okie dokie… There is a lot of great info here. Kudos to the posters who contributed, but, (I know, when the word “but” is used, everything prior to that word doesn’t count, but, it does in this case …) when I read the initial question, (first post of this thread), and then read through all the responses, I felt like everyone was “throwing up” information on this poor guy, all in an effort to inform him with as much knowledge as possible so that he can make a very informed decision before he installs an induction system on his Z car. I applaud the efforts of every one here in that effort, but was all that information needed to answer his question directly or in this stage of his learning about induction systems? (I used that word “but” again didn’t I? Oops, sorry…) I know, everyone is just trying to help and you all are doing a great job, but remember back to when you were in your infancy of learning this stuff. Too much information can add to the confusion that most likely already exists… (I didn’t say “but” again did I?...) I know you guys are going to think I’m biased because Ron is my partner, (I am happily married to a wonderful “woman” for 18 years now, so don’t get any ideas...), but we are “business” partners because we see this sort of stuff on a similar level, (not everything mind you as he is a MAC user! ). If you step back and look at this, you’ll most likely agree. Ron Tyler’s response summed up Typhoones original question rather well. Ron did leave out the attributes of Throttle body injection though. Throttle body injection is, in my opinion, a glorified carburetor. It has the attributes of keeping the butterfly/s in the throttle valve clean by spraying fuel on them directly, (gasoline is a great solvent for cleaning parts right?), and allows for pinpoint fuel map tuning if the ECU allows you to make adjustments, i.e stand alone EFI. As for fuel distribution, throttle body Fuel Injection suffers from the same issues that Carbs do, but allows for more precise fuel control vs a carb over a broader spectrum of conditions, i.e. temperature, altitude, extreme RPM changes, Artificial aspiration, etc. Multi port EFI expands on that to whole another level with the possibilities of individual cylinder fuel trim, exotic intake manifold designs, etc… Ok, now “BRAAP” is done hurling on this guy for now… Paul

Welcome the wonderful world of high performance cylinder head building. Valve train set up can be time consuming and for most, it can also be quite confusing. If the valve seats were cut/ground deeper into the head, then yes, you would have less seat pressure. As for how much seat pressure you would loose for a given spring installed height change? Depends on the sprig rate itself. If your spring manufacture supplied that info, you could calculate the loss in seat pressure. For high end performance head work, it is always best to verify this using a spring tester. There are also many other things that need to verified as well such as over the nose pressure, retainer to stem seal clearance at full lift, coil bind with the cam being used, etc. etc. etc… Here is a great thread on what is involved in building a custom L-series cylinder head with lots of pics and details of the tools and processes involved. http://forums.hybridz.org/showthread.php?t=108398

That is AWESOME news. Congratulations on getting your MS controlled Z up and running, “reset free!” Keep us posted on your progress, Paul

Back in the mid ‘90’s I did run a true dual exhaust on My L-28 and ran the exhaust out through the bumper holes. I had modify the OE fuel tank by shaving off that end of it to facilitate this, lost approx 1.5 gallons, I don’t recall the actual volume lost. Then when I installed the V-8, I had to open up the holes in the valance to accommodate the larger dual 2 ½” exhaust. Personally, I like the looks of the exhaust exiting that location, though the fuel cell is the better way to approach this. For my current V-8 project, I plan to do the same thing, though this time around I’ll run a custom fuel tank or fuel cell. The original BRAAP Z…

With Mega squirt, you have TOTAL unimpeded control over fuel and spark to tune around pretty much any thing you do to the engine, now or it eh future, i.e. alcohol injection control, radical cam, crazy boost levels, run distributor less ignition, run the cooling fan, Nitrous and even have separate fuel and spark maps for Nitrous etc. With Mega Squirt you will be able “dial in” the package. As for the OE EFI route, you will be limited to what you can do to the engine and still maintain smooth transitional throttle response with no flat spots in the power band as you don’t have “full” control over the fuel and spark maps, and you won’t have the ability to incorporate accessories such as additional injectors, alcohol injection, etc to be controlled by the ECU. My opinion is if you pan to move very far away from stock components, boost levels, etc, definitely use an aftermarket standalone Engine management such a s Mega Squirt or WOLF and you wont be limiting your power potential due to your engine management system.

JSM, Sorry about that, I assumed that you were more familiar with the Ford EDIS. “EDIS” is FORD and Ford only. Other auto manufactures have their own Distributor Less Ignition systems, and some of those coil packs from those other manufactures DIS will work with the FORD EDIS ignition system, but EDIS is proprietary to Ford only. I get the impression that you haven’t really looked at what EDIS is or how it is controlled via Mega Squirt with the Spark Extra code, MS-II, or Mega Jolt Lite Jr? EDIS needs one of those to function fully. EDIS just happens to be one of the easier routes for converting over to DIS, but it isn’t just a “bolt on and go operation”, (I wish it were that easy). Your specific questions of what years, brands, etc are ALL answered in the various Mega Squirt and Mega Jolt Lite Jr sites within their online manuals and forum archives. Even detailed diagrams of the parts, wiring, mounting, programming, configurations, etc. A quick search within the MS and MSextra forum archives you will find where exactly within the engine bay to look for the various EDIS parts. This “Mega Squirt” section in the Hybrid forum is more or less support for Z specific Mega Squirt installations, including the use of EDIS with Mega Squirt. The details of what EDIS is, how it works etc, is covered in detail in the “mega-manual” on Mega Squirts home page. This first link is the best EDIS primer that I can come up with… Here is the EDIS specific MS info… http://www.megamanual.com/ms2/EDIS.htm'>http://www.megamanual.com/ms2/EDIS.htm Mega Squirt info page… http://www.megamanual.com/ Mega Squirt Spark Extra code forums… http://www.msextra.com/index.php Mega Squirt & Spark Extra Manual with EDIS details… http://www.msextra.com/manuals/MS_Extra_Manual_Index.htm This the Mega Jolt Lite Jr. For Carbureted users wanting to run the EDIS ignition stand alone. http://www.picasso.org/mjlj/ In short, the EDIS ignition system was used in late ‘90’s Ford vehicles. Essentially if it is a mid to late ‘90’s Ford product, it will have EDIS. In perusing the U-Pull-it yard, the Coil pack will be your first indication that you have an EDIS equipped vehicle, (V-6’s for EDIS 6), then look for the EDIS module in the Engine bay which will have the word EDIS-“x” in large print right on the module, (“x” being the number cylinders, i.e. 4, 6, or 8.) Have fun and good luck, Paul

If you are looking for “desirable” years vs “non desirable” in an attempt to get the best performing parts, I don’t think there is any. If the vehicle has EDIS, then it’ll work. I briefly looked into finding a more desirable year or part number for modules, coil packs, etc, when I first started committed to using EDIS on my car. The deeper I got into it my research, the more I found that EDIS is EDIS is EDIS. The main things that you do need to be aware of is… 1) For a 6 cylinder, you have to use EDIS-6, for a 4 cylinder EDIS-4 etc, 2) Whatever Ford car you get your 36-1 crank trigger from, be sure to use that VR sensor from the same make and model of car. The VR sensors are different from engine to engine. The voltage produced from matching VR and 36-1 crank triggers are all pretty much the same so any EDIS module will work with any “matched” 36-1 n VR. Read this as it covers just that about VR sensors and 36-1 http://www.msextra.com/viewtopic.php?t=14920 3) Follow the EDIS instructions for MSnS-E during your setup and configuration and trigger wheel clocking. Good luck, Paul

Well my scales seem to have issues with relevancy … so my best guess for an accurate actual weight is between 2000 and 2800 lbs for my ’73 FSP car.

I did not use any spacer for my 60mm Nissan TB and for throttle actuation, I used the universal Lokar Stainless cable kit, (under $40), fabbed up a bracket that bolts to two of the OE heat shield bosses on the bottom of the manifold to support the cable bracket on the engine. At the gas pedal , I just drilled out the pivot ball swage, rounded off the top of the gas pedal arm itself and the Lokar clevis fit it perfectly. Cut the cable to length per the instructions, adjusted for idle and full throttle application, project done. One last note, don’t forget to leave a little slack in the cable between the engine and firewall as the engine WILL shift forward on its mounts under heard braking and this WILL apply throttle. Yeup, it sure does… Any how, the installation was literally that easy. Quick simple, clean, and “very smooth” throttle application as Lokar throttle cables are Teflon lined. We are a Lokar dealer, if anyone is interested, we sell both the braided black and braided stainless, just contact us at; ruschmotorsports@hotmail.com

The short answer is no. Well, technically the answer is a maybe, but the work required to do it vs. just using a different rack makes it REAL hard to justify. The ZX is a rear steer design, the S-30 is a front steer design. To utilize a ZX rack in an S-30 car would entail having to build a custom cross member, switch the T/C rods from rearward to forward as on the ZX to clear the tie rod ends. Then you would need to use ZX steering knuckles and being as the ZX steering knuckles wont bolt directly to the S-30 strut tube, you’ll have to have to find a way to get the ZX struts under the S-30 body and being as the ZX king pin angle is shallower, you’d have to relocate the upper strut mount, etc. etc. etc…. In short, it would just be way easier to use the entire ZX car than try to use its rack. The easiest solution for steering alternatives in the S-30 car, (like power steering for us older guys), is to use other front steer designs such as the Subaru, Miata, Ford Thunderbird etc. Those are the only racks I’ve heard of being using in the S-30. I’d LOVE to see a sticky or FAQ posted with a list of the different racks people have installed in their S-30 cars…

First off, Kudos to anyone brave enough to carry engine parts into a supermarket to weigh them. (I still chuckle just thinking about it.) Also, thank you for going to such lengths for quality accurate data. Good work. Ok guys. I’m sure I’ll get flamed for this and if so, great! It’s been a few years since I’ve been roasted, so I guess I’m about due… I personally don’t understand what the hang up is over the weight of the individual parts such as block only, cranks only, etc?! Ok, I can see where that bit of information would be a neat piece of Trivia to have for bench racing in the shop. But knowing the weights of the individual rotating and reciprocating parts is pretty much useless in comparing the overall weights as both engines HAVE to have these parts and there really aren’t many options available to alter the weights of those parts to a point that is substantial enough to warrant weighing them individually. Sure, the BARE block of the LS-x weighs considerably less, HOO RAY!! Uh, I mean, HOO cares?! Comparing the weights of just the bare block is like trying to compare “HP per valve” or “HP per cubic Millimeter” of your V8-Z with some 16 year old and his Honda! Means diddly squat! What really matters is how much does the “engine” weigh, i.e. the sum of those parts, (we’ll get to “sums” in a minute). So in comparing two similar yet different power plants, (“weight differential” WAS the theme of this thread, not “absolute weight”), why not just leave the parts we really don’t have much control over in regards to their weight, “in” or “on” the engine, and compare that as a whole? Things like intake manifolds, headers, starters, etc can be quite different in weight so those can be a part by part weight. Really, how many of you guys are just installing BARE blocks in your cars and driving them that way? If we could, then just the weight of the bare block alone would have merit. I personally could care less if a block weighs only 5 lbs if the rest of goodies like the oil pan and water pump are going to offset its overall weight. To me, it is the overall weight that matters. Power to “overall” weight ratio is what accelerates our cars, not power to “block” weight ratio. Now on to “Sums”… Lets say you get all these individual weights such as block, crank, rods, pistons, cam, oil pan, etc etc etc. Then are you going to add up those weights to satisfy your hunger for wanting to know what the “total engine” weight is? With so many parts there is just that many chances for error, not too mention are you guys going to measure the weight of each and every part down to the gram? Most likely the weights will be rounded to the nearest pound if that, and that is if the scale being used is even accurate to +/- a pound, (Cumulative error now). Basic statistics here guys. The engine needs the crank, pistons rods, cam etc, and for 95% of the builds that we are doing, all those cranks, cams, pistons rods, etc for a given engine whether it be Traditional SBC or Gen III LS-x, will be very close to other available options for that same engine. The original point of this exercise, (this thread), was that there seemed to be lofty claims of massive weight savings, and if that is true, great, nothing would make us happier, but we had a hard time seeing it. Sure there could easily be more than a few pounds weight savings, but we are not seeing the 55-90 lbs differential as claimed. Maybe someone will come along and either support our findings or find that 90 lb weight savings that we missed with comparably built/setup short/long blocks using one scale that is accurate, not just individual parts and then adding up those weights. If absolute weights are what you guys want, why not just start a thread in that theme? This thread was started as differential, not absolutes. Absolute weights of these engines IS worthy of its own thread entirely. BRAAP,…. out.

Very well said. Thank you,

Ron, You know what I mean... I don't see the need for that comment... Mikelly, I’ll be honest, I have no idea what you meant other than you possibly would like to see a bare block to bare block comparison? As for those stacked parts on the L-98, that was in effort to get an apples to apples weight comparison. Being as the LS-1 has the cam, damper, water pump, front cover, “installed”, and the L-98 “didn’t”, we didn’t think that installing those parts vs just stacking them on top would have much affect on how much it weighed so we just stacked those parts on top. This was just to get an idea of “comparably equipped” short blocks. I’m pretty sure that is what Ron was getting at. Yeah, I agree 100%. B-room scales are not a great choice for this type of data gathering, but we weren’t going for exact figures, just a general idea as we have heard/read that the difference between the traditional SBC and the LS-x as being between 55-90 lbs, and no one could agree on that either. Being as we happen to have an L-98 short block out of an ’85 C-4 Vette in the shop AND a 2000 C-5 LS-1 also in the shop right now, it was inevitable that our casual shop talk would turn into “lets see for ourselves”. We were both struggling to see this 55-90 lb weight savings that the LS-x is supposed to have over the traditional SBC, (yet we both strongly agree that the LS-x in any fashion of street build makes more power over a broader range, more on that later). Yes the bare block of the LS-x should be lighter, but the LS-x also has a massive water pump and that large bat wing cast aluminum oil pan that could offset that weight savings. Our goal was to just get an “approx” idea of what the difference was as our feeble minds just couldn’t fathom 55 or more lbs difference, so our casual shop talk turned into “get out the scales and lets perform a back to back “short block” weight comparison… and Wa la, this thread. Back to my original point of this post, yes there can be quite a difference in the readings just by where the weight is placed on the scale itself, especially bathroom scales. In an effort to minimize that error so that we could get a somewhat repeatable relative IDEA of the differences in short block weights with out having to deal with placement errors, I’ll just quote my previous post… Is this last comment meant in regards to our original posting of our “informal” testing procedures and findings or the posts of others refuting our informal findings? We honestly had no intentions of posting hearsay type information, just info that we feel has some merit and value to the Hybrid community.

Are you thinking about something like that ITB for your N-47 head? That ITB manifold pictured is for sale?…… MUHAHAHAHAH

Ok, playing devils advocate here. It seem like John is wanting to redesign the strut suspension in such a way as to eliminate any and all loads imposed on the strut shaft that induces stiction, or at least in the fore and aft plane? I’m sure a Lower Control arm can be designed that would not allow the strut shaft to endure any “fore and aft” loads therefore reducing stiction in that that way, but the time invested in engineering such a part, you have to ask yourself, how much less work would it have taken to just design a double A-arm or some other “non” stiction suspension design? Also, if you were able to design such a LCA to take all the “fore and aft” loads away from the strut shaft itself, the cornering loads will still be present inducing said stiction. Seems like a lot of work for how much possible gain in track times or tire tracking over uneven track surfaces? And you will still have the side loads from cornering inducing stiction. It seems from a design perspective that it would-be rather hard to eliminate or even reduce the already existent side loads presented on the strut shaft to a level that would reduce stiction to a level that makes enough difference to be noticeably effective. A strut by definition is “supposed” to take those sort of loads, and to design a suspension that doesn’t side load the shaft of the “shaft” itself, is another suspension design entirely, i.e. no longer Chapman or McPherson strut. To me, if the idea of keeping it a strut type suspension is the goal, wouldn’t it would make more sense to spend the time energy and money designing struts with reduced stiction such as installing linear bearings internally in the strut with low drag seals, or maybe pressure fed plain bearings like the main and rod bearings in an engine? (The pressurized plain bearing idea would add lots of weight and complexity with a fluid pump, hoses, etc. and probably isn’t realistic, but it might reduce friction induced from strut side loading.) If you were able to design a Chapman strut suspension that takes away “all” loads that induce stiction in the strut shaft, by definition, you would no longer have a strut type suspension. Then it’s back to the drawing board for a new suspension design…

Skiddell, I’m glad that you are able to run 11:1 compression ratio and apparently have no engine damage. I’m sorry we can’t do the same here in the US with our Pump gas, though we do run 12:1 and higher with AV gas and Race fuel quite regularly, (I’ve built more than few L-series heads for high compression L-series engines for people on this forum). I personally am running close to 12:1 in my L-28 powered 240-Z race car with 100LL Av Gas, and a very aggressive ignition advance, 42 degrees total timing, and it runs GREAT! (I’d probably be better off with around 38 degrees as it is a high quench MN-47 head). Ok, now as for your Octane comparison between the US and the UK, None of your math formulas are going to dispel the plain fact, (and well documented fact on this and other forums), that here in the US, the L-6 engine using the open chamber heads, i.e. E-88, N-42, N-47, WILL and DO detonate AUDIBLY, not just lightly or silently, but LOUDLY, with 91-92 octane Premium pump gas in the US and that is with only 9.5:1 compression ratio! I do agree that running as much compression ratio as you can, would be ideal. As a professional engine builder, my belief is that you should always build in as much static compression ratio as your fuel will allow, WITHOUT having to back out any ignition timing from the ideal timing that engine combination prefers. I strongly believe that if you sacrifice ignition timing just to acquire a small increase in static compression ratio that you are going backwards in regards to power output. For a street engine, even if you sacrifice a little static compression, so be it. You wouldn’t be able to feel that small loss in the seat of the pants any way. Custom pistons for the L-6 are very expensive and for most street applications/budgets, a small sacrifice in ideal compression ratio is usually a compromise most budgets are willing to live with. At some point, you have ask yourself is 5-10 HP worth a set of $800 pistons? (US dollars). At $80 per HP at best, that is hard to justify. For US Pump Gas L-6 applications, I stand firmly 100% in my original post in this thread.