Gollum

I think it'll work for your goals as long as the head is healthy and you induction system is well matched. I'd suggest playing with cam timing when it comes time to tune too.

This just about made my evening. ...then I remembered I still haven't ordered my MS-ll. Doh!!! (goes off to hide)

I agree that the EFI intake isn't an ideal mathc for running a long duration cam, though that doesn't mean it can't be done. So consider me seconding Pyro's view on that. Regarding the Z31, going that route and adding nistune is JUST AS EXPENSIVE AS GOING MEGASQUIRT! In fact i'd say it's even MORE expensive! If you want to do open source tuning and install your eprom yourself it can be done cheaper, but it's still going to be a lot of time and energy just to get a system that works almost as well as megasquirt. If you already have a Z31 ECU and harness available it's a worthwhile option to consider. If you want to run a stock-ish turbo setup it's a very pleasing option as just a plain ECU swap with the MAF sensor is a huge upgrade and will run a stock longblock L28ET very well. No tuning required really. But if you're looking to snag that 10-15% extra power sitting on the table, just go MS or something better even.

Funny, when I see that head I think E85. Freakin' screaming at me actually. Slap a P79/90 on there with some quench and ADD BOOST. I'm not sure what you're looking to spend on this, but I personally don't see the point in spending a ton of money on a fancy dual ball bearing turbo if you've got E85 combined with decent compression. I'd definitely also go the solo-turbo route, not twins. But that's just me. Some people get all crazy for fast spooling turbos, but I just never seem to have an issue with it personally. When racing it's not really an issue, and I'd rather it be easier to stay out of boost when I want to. I've driven cars with very fast spooling setups and it seems like it looses half the benefit to me. I Like that a turbo is a dynamic power adder, and can be turned off with a careful foot. I've ridden in 400hp STI's that use the stock turbo, which is NOT ball bearing and they spool PLENTY fast from 2500rpm on. An example of this would be that in this setup you can take off mildly from a stop light and make a turn through the intersection, put the car in 2nd and mash the throttle and suddenly you're sideways even though the engine was bellow 2k when you put it in 2nd.... PLENTY of oomph. A similar pairing in a L25 could be pretty lethal. Give if boost-happy E85 and that piston with a matching head chamber and you have a recipe to cause a pretty capable turbo to MOVE.

Should have come to Mt. Diablo a few weeks ago.... I'm sure you could have gotten a ride in some Z cars. I'll first put out there that I have very little experience with what some consider the "more agressive" stock L24. I've only ridden in 1 stock longblock 240Z and it was probably on putting around 100hp to the wheels, if that. But I've also ridden in, and driven, a few L28 equipped 240's, and it's amazing how much better they feel from a stop. Point being ~ You can do all sorts of tricks to increase VE, but increasing it down low just seems like a backwards way to go. A 2.8 liter S30 will have ZERO issues with having enough torque to handle hills unless there's something seriously wrong. And no matter what, a L28 that's making a healthy 200hp at 6,000 rpm is going to feel way better all through the RPM range than a L28 making 170hp at 5,000, even if it's making more torque down low. That's my .02 cents. Oh, and all that said my S30 has a L28ET... When I get it running again you can come drive it if you want to head up to vacaville sometime.

I'm really glad you just went ahead and did it. Too many people get a bit freaked out by some of the simplest issues. There's no reason to freak out about any possible damage to the block. I would have been much more concerned about how secure everything is so that there's no chance of DROPPING the block. Concern for the threads would have never even:-entered my mind. Engines are some pretty tough legos.

Where do you think I first got the idea of multi-engined cars? When my parents got satellite TV back when I was 12 years old I watched almost nothing but car shows all summer long. As much as I hated nascar, circle track, sprint car, tractor pulling, etc it all ended up having an effect on me. It was all racing and was about 1,000X better than anything else I could find on TV

That's some epic win material right there. That's got to be the most creative harmful solution ever.

You just gave me an idea! Ratchet strap battery tie downs!!!!

Sweet, thanks for the input Tony. I'll have to run some numbers and calculate a setup and have you grade my paper, oh teacher of boost. Here's another question that's probably not as big of a deal, but still just hit me like a baseball in the head. In a compound turbo setup, I can't see any reason to use more than one BOV, but if you were to recirculate it, should it recirculate to the last state of compression before the engine, in order to keep your most immediate compressor spooled, or do you recirculate it to the FIRST state of compression in order to balance the pressure in the system as a WHOLE?

Boy has a lot changed since I updated this. Hopefully I'll stay motivated to update this thread in the next few days. Here's what I worked on today: My car is bulimic. It's amazing what all she hawked up today. It's also amazing how few wires are actually needed to run an engine and have enough lights to be "legal". I'm almost down to the bare essentials now. I think when I go MS I might end up with nearly as many wires on my engine harness as I'll have chassis harness!

So, getting back on topic... Does anyone have some good calculations on how to factor compressor sizes when compound boosting?...

All totally makes sense. I never expected to get 30mpg, so please don't read it that way. I was simply asking for more details on the though process. If I had to make a completely uneducated guess I'd estimate at average combined tanks ranging from 14-20mpg. 7 seems retartedly low, but then again it will be a VERY different setup that anyone doing would probably care less about the MPG attained.

I'm not going to ask you prove this, I just want to know your thinking behind it. Are you assuming MPG goes down squarely to displacement of the rotary? Because that's inherently not true with regular applications. The 6 liter LS2 can manage 30mpg highway in a S30 chassis when paired with the .5 OD T56 and a tame foot. If GM made a 3 liter V4 version I highly doubt it would reach even 25% better fuel efficiency. MPG is a complex equation that I'd suggest might be even harder to perfectly predict than horsepower. The only thing that makes people shrug it off is the small window of figures. But the nuances are immense. Every factor there is to making power effects MPG, and there are other things that DON'T effect HP that will certainly effect MPG. I'm not saying a 3x13b won't have pitiful MPG. I'm sure it will. I'm just suggesting that if 1x13b gets 21mpg then that doesn't mean three will use three times the fuel. Now, under FULL THROTTLE I'm sure that might very well be darn near the case, minus aero and drivetrain factors. But you're not driving WOT 95% of the time you're in a car, unless it's a dedicated track car.

Well the stoke MAF system will compensate inherently for altitude. That's just the nature of how they work. The gas issue might be a concern, but you can just change your static timing to adjust for gas. It won't be optimal power, but it'll run fine. If you already have it all, then DO IT! See how it performs before assuming you need to program/tune the ECU. It all depends on your goals. If you're shooting for 300 or less WHP then you're probably fine. Here's a link though on tuning the Z31 ECU. I also have the live edit files if his links are dead. http://redz31.net/pages/fuel/romulator.html

Actually you're very correct regarding BMEP. It's a much "truer" measurement for efficiency than torque is. Maybe since our OP wants to talk hard numbers, maybe he should tell us what BMEP he's shooting for. Regarding stroke and torque relation, I can agree to a point. I think it has an effect but not like people seem to think. What you loose in leverage you gain in flow potential for the given displacement, and if you increase the flow for a given displacement then BMEP will go up and subsiquently torque as well. I know this might not be "scientific" enough for most people, but using a semi-accurate program we all know, dyno2003, I just built a motor to compare this will. I've got the valve size set to "auto" so that as I change things around the valve size would be approximately the same ratio to the bore and as valve size changes so will estimated head flow. So in this example we don't have a static head and flow numbers, which isn't "real world". I say that as a precursor to isolate the stroke/torque discussion. In the real world stroke is good because our head is static generally, and we get more displacement, torque, and power generally by doing so. That said, peak Torque at 4" bore and 3.5" stoke (351 ci) is 451 at 4500rpm (79 lbs per liter, this isn't a mild motor). Switching nothing but bore to 4.32" and stroke to 3.5" (351ci) the torque peak is 467 at 5500rpm (81 lbs per liter). I know many people bag on this program, and I admit it's not the most advanced program out there. But it's also generally recognized that when used properly it can produce accurate information, showing that it's math formulas are fairly solid. I've replicated many dyno graphs fairly accurately by accurately entering data, but I can also see that it's just a tool in my box, not a law to live by. So people, please realize I'm just saying all this to bring up a point, which is that peak torque numbers have a lot more going into them than just displacement, or stroke, or both. I've seen people blindly say that stroke is the main factor in torque (which I don't believe is what Leon is saying) and I've seen people say that displacement is the only factor in torque (which is not what I'm saying either). Though both of those play a crucial role, there's many things that make up a good 10-20% of your torque figures. For reference, the motor example given had a 10:1CR, 800cfm rated induction system, sequential fire injection, large tube open headers, cam with .614 valve lift and 286 duration and 110 lobe seperation. I believe a similarly built 351 would be close in numbers, and I've seen it done. Reason we don't see many actually put out 450+ torque and 470+hp like this simulation did I believe is largely due to lower compression and poor intake design with a carburetor that's not great at flowing evenly to each cylinder. This simulation is assuming that each cylinder is getting exactly the same air and fuel, which doesn't happen without very well designed induction and fuel systems. By comparison these numbers perfectly line up with what a LS1 should make with a similar cam, which is basically what this motor would be. The biggest difference would be the exhaust at that point which is about 25HP difference according to dyno2003. That said we have people ON THIS VERY FORUM putting 400+ to the wheels in LS1 motors... some even still get 30mpg on the highway, those bastards.

In all honesty I don't think you save much going with the Z31 setup over megasquirt. I've gone back and forth for the last 3 years on which is the better route (without yet doing either myself) and in the end my mind has always been set on a MS2 setup. I know I can do it for under $500 and I don't think I could do the Z31 setup for less than $200 unless I found a good deal on craigslist. Local yards are ridiculous and even ebay can be a bit steep I think. And in the end to make the Z31 ecu programmable ends up costing as much as MS2, so what's the gain? I'm not saying don't do it. I'm just saying make sure you don't end up doing the same work twice, spending twice the money. Do it once in such a way that it will last you for a while.

While I've been on the toque bandwagon before, it's always been because of one thing - POWER CURVE! People seem to really misunderstand torque and how it truly relates to engine performance. Even here we have Daemione guessing that F1 is possibly sacrificing torque for power. The only appropriate phrase that comes to mind is "complete bollocks". People in the racing world will usually NEVER give up torque in the end. People might think that because race motors can be gutless when out of their optimum range, and people can say "well it's not torquey, but it's fast" which again is a pile of POO. Race engines have LOADS of torque they just shoot for it to be as high of a RPM as possible. You can't have a completely flat torque curve everywhere, which is part of why a F1 motor idles at 3,000. Does it make as much torque at 4,000 as other 3 liter motors? Probably not. But I bet it makes more torque than most other 3 liters when it reaches it's torque peak. The only reason I've ever seen people actually give up torque figures, is for a BROADER torque peak in order to give them a BROADER HP curve. In this sense they're actually going for more "average usable torque" or "average usable power". In the end, JohnC is right. But Leon is right too. Torque for the most part has no real value. HP is what moves a car and is ultimately important in most of our goals. We're not trying to move a 10 ton truck with a 20 liter diesel. We're moving a sub 2500 pound car in as spritely manner as possible. To do this we don't just want a ton of torque in a small range, nor do we want HP that is a fancy number but doesn't seem to do much. What we really want is a good POWER RANGE. And that's where I think torque can have it's place in this discussion. I think we've pretty much shown that 200hp is possible sub 7,000rpm with pump friendly compression. But the real impressive side of this discussion is that it's so easy to obliterate the 200hp goals if you're willing to run a semi-race compression setup, that I think it could be interesting to know how soon you could reach 200hp in the RPM range with a more street minded setup. I bet it could be done at under 5,250 and done right could have a fairly flat HP curve from 5,000-6500 (on 2.8 liters). Now that could be a killer street engine. Even if you fell short and only had 180RWHP for over a 1,500rpm range that'd make for a killer performing car, well capable of getting a Z into the 13's which isn't a slow street car. Just takes a well flowing head with minimal port enlargement combined with the right cam, intake and exhaust to all work as a system, then the system to tune it all.

Thank you very much for not only clearing that up for me, but explaining it in such a way that most of us should be able to grasp. On the topic of intake tuning, I remember seeing a "intake dyno" of sorts in a book a read a little bit ago, "how to tune and modify engine management systems". It was merely to show the effect of tuning to different harmonics on an engine. I wish more info had been given, but it was intriguing in the sense that while tuning for lower harmonics offered higher benefits at given RPM, the best broad range power was gained by tuning to the 3rd harmonic if I recall correctly. Without diameter and taper data it's a bit of a broad stroke, but still interesting to think about.

Don't apologize. It was a worthwhile read and I seem to remember read some of that before... My bad. To be fair, now that I think about it, most of the improvements I've seen in going to smaller diameter pipe were probably as much due to bend quality and radius as much as diameter. Meaning a 3" pipe with crappy tight radius crush bent curves can have severe restriction/friction while a smaller system with smoother bends can actually have LESS restriction. I think though that you would agree though, leon, that my statement holds true when talking about headers. There is such a thing as going too large or two small on your primaries. My point though more than anything else is that there is such a think as mismatching your induction and exhaust systems in BOTH size directions, not just one or the other. If you want to maximize torque in a particular range, you'll need to make sure everything from your throttle body (and before actually) down to the muffler are optimized for that flow and velocity. Something that comes to mind is that you don't just tune intake runner length, but also diameter. It's why design parameters are so important. Something that's kind of bothered me about some of the assumptions that have made in the attitude of "this is what production cars do so that's what I'll expect" seem rather ignorant to time tested experience that I've had myself and seen time and time again by others. You can take a completely stock longblock and gain TONS of power (including torque) by removing OEM restrictions in the system. An OEM doesn't design everything with raw performance in mind. A good example is the NA VG30E dyno that's on Jason's site: STOCK longblock (chassis dyno) plus upgraded intake pre-throttle body, and exhaust (engine back), and fuel system. The stock VG30E should have 160 BHP, so that first graph of 130 might suggest that either the dyno is reading low, or that there was power lost from the upgrades maybe? Either way, something is certainly a tiny bit low on that dyno but it's within the ballpark of what would be expected. But then you see what happens with cam timing adjustments. WOW. Not only is he now putting down more HP to the wheels than the engine was rated at BHP, but he picked up enough torque that if assuming even an absurdly low 12% drivetrain loss that's a good 68lbs per liter, if we assume a more realistic 15% that equates to 71lbs per liter. And that's a completely stock VG30E which is a 2V head!

I also just found this great article on the subject of torque per liter. Even there they state that 90lbs per liter isn't impossible http://www.pumaracing.co.uk/POWER2.htm What I think can also get us really screwed up on this topic, is that for a race car having less torque overall can be desired if it's giving you substantially more torque at higher RPM. It's not hard to get really high torque per liter at lower RPM if you create a system that's well matched for that RPM. The reality though, is that many people get crazy and put parts on their engine that don't match the flow of the system. It's like how you can put too large exhaust on your car and loose considerable torque. This isn't because you have to give up torque for increase high RPM flow. It's amazing how many times I've seen guys with crush bent 3" exhaust on a sub 2.5 liter engine. In most cases if they switched to a smaller diameter MANDREL bent exhaust they'd pick up Torque AND HP. A low volume/diameter port can make just as much torque as a large volume/diameter port, it will just have to be in a different RPM range. We can build a stump puller Ford 351W that makes 75lbs per liter at 2500 RPM. In order to get the same engine to make that torque at 5500 it'd take totally different heads, intake, exhaust, cam, etc.

Manufacture specs are regulated and the few times that there have been cars that don't live up to ratings there's costly recalls for the manufacture. Some examples are the early RX8's, and the early DOHC Cobras. In both cases the manufacture took back cars and rebuilt engines, and then later fixed issues or changes the rating in subsequent years. By contrast though, there's no laws or regulations mandating that manufactures can't underrate their performance. The new 2011 Mustang GT's with the Coyote V8 are an example, where even the very low dynos are showing figures that show that Ford probably underrated the engine a good 3-5% at least. Some of the dynos that are known to be "pretty number" dynos can show nearly at the wheels what should be at the crank, which definitely starts to indicate that something is up. Same thing happened with the 03-04 cobras, but it wasn't as impressive I think because it was a supercharged engine and Ford was just being cautious with their previous flops. Point being - it's more common for there to be underrated engines than overrated engines from every shred of evidence I've experienced and seen. And on the second point you brought up. F1 engines by what HP they're supposedly running, at the RPM limit they have, they're making AT LEAST 100lbs per liter at peak HP and that's with a bunch of regulations that restrict power. If you believe what has been said that they're capable of over 1,000hp if there weren't restrictions then assuming the RPM stays close (which might not be true) then that would put torque at over 116lbs per liter! All that said, I do believe that things vary dyno to dyno and comparing figures against each other can be taken way too seriously and is best left to just the realm of speculation. But that said some of the people that have posted have actually had their engines on ENGINE DYNOS which are incredibly accurate. I'm sure tony could chime in here, but just looking at what RPM some L engines we know operate at, and calculating what HP the engine is actually putting down via performance numbers, it's amazing what torque has to be created in order to get those numbers. It's certainly not F1 numbers, but it's certainly more than most NA production engines.

I do believe that I have yet to argue either way, which I would think in a sense is "bowing out" so to speak. I've never intended to question anyone on the subject and don't wish to argue on it, which is a rarity for me. Trust me, I have a deep passion about words and how they're used. I also have little patience for arguments when everyone in the discussion understands what everyone meant without confusion from the onset. Now, if there needed to be clarification because someone didn't understand what was being communicated then there's a good reason to have a discussion as to why a word is used for something. But in order to maybe take this minor conflict in a positive direction. Let's bring it into something useful that takes us somewhere. So if we use a cooling device after a compressor outlet, but before the engine we might call that an intercooler. If we take that charge and then cool it before sending it somewhere outside the system it's an "aftercooler", but what about cooling a charge at the inlet of the first compressor in the system? Obviously something like a traditional air to air cooler wouldn't be used, but something more like a liquid injection cooling, or a water-air cooler. Would that be called a.... precooler? Reason I even bring it up, is that if you've got a compound setup, controlling inlet temps could be quite important if you live somewhere that outside temps can get over 110 degrees on a regular basis.

You could even just get a VQ35DE and rebuild it with better internals and have a very similar motor. Not quite as amazing heads and block, but certainly more amazing price.

Sorry you thought I had tar and feathers waiting, that was not my intent. Maybe I needed some smileys to show my lightheartedness? If anything I was trying to hear what you had to say on it, and why but didn't want to force you if it was a sore subject that we didn't need to beat to death. Again, as I said before I could care less about nomenclature. It changes constantly through history and I personally believe I'm only required to learn enough to communicate effectively with those I interact with, and since I'm not in frequent communication with engineers in the field on a regular basis I haven't had the need to make a discrepancy. I'm not promoting the continuation of ignorance because that'd just be backwards. But I'm saying we can't all know everything in the world and you have to choose what to go after.