I'll chime in with some info that might help. I'm workong on the heads of my QV, which are very very similar to 348 heads...infact 348 heads will pretty much bolt on to a 308. http://www.ferrarichat.com/forum/showthread.php?t=129621 What I found so far is the 348 intake valves are too small to feed a 3 liter to 7700 rpm, much less a 3.4 liter. With the 348 valves (and dumping the stock CIS system), I've got the intake flow up about 35% to where is should make 320-325 hp at 7700 on a 3.o liter. The next set is 32mm intake valves, I really want to get the flow up at least another 10% before I call it done which should bump the hp to about 335-340 ish at 7700. If I were going to try and rev 10% higher, to say 8500, it would need another 10% more flow to feed it, probably another 8-10 degrees of cam duration and would make 360-380 hp. I'm opting for a supercharger rather than adding the revs because it makes more power with less stress on the engine, it will be 650-700 hp when it roll out in the spring (up from the 520-540 it had with just the supercharger). The moral is that the stock 348 heads don't flow enough to feed a 3.0 liter. To really make a 3.4 liter run, you'll need to pull the heads and get them flowing properly along with adding an intake and exhaust that match and should easily be able to hit 400hp with an 8500rpm redline . The HP will relect the lowest flowing component, not an average. Because the heads are so similar, the port designs that work on a 308/328 head will also work on a 348 head, so if anybody is interested, I'd be happy to give you the contact info for the shop I'm using....he's got a lot of hours into my port design and will know exactly what to do for you.
Ah, my favorite mad scientist has chimed in. Thanks for the info Mark. I sent Andy a pm asking him to chime in on this matter. What Mark is saying makes sence because Andy's car did have the heads ported, if I remember correctly. I'm not sure if he is running different headers on his car though. But he did say that he was putting down 400hp.
Did any of the 348 Competizione LM's have different heads or valves? How do the valve sizes on the OEM 348 heads compare to those on the 288 GTO (~~ 400 hp, right?)?
I'm not sure of the valve sizes, but the GTO made 400 hp with something like 15 psi of boost....it was force fed, so it only had to make about 200 naturally aspirated Remember too that what was the hot ticket 15 or 20 years ago may not be that hot by today's standards. There has been an awful lot of learning going on, lap records have gotten broken each and every year. If the engine only picket up 1% per year, is about 21% over 20 years. My buddy Vic who's doing my heads says that he's now getting a higher velocity on my head than any head he's ever had on the flow bench in 15 years of running it and it's still not flowing enough air for a 308.....not it's not nearly enough to feed a 348. The 348 valve is 30.5mm. I'm pretty sure 32mm will be the ticket for a 308. That would suggest more like 34 or 35mm is what a 3.4 liter would want for 7700 rpm, maybe 36 to spin it to 8500, assuming the same port efficiency can be achieved. That is a big jump from 30.5
Mark, I don't understand. If the valves flow enough air, then they are large enough, force-fed or not. Didn't you and I look at your spark plugs and conclude that you were running lean (too much air already) on your supercharger version, or have I gotten you confused with someone else? 348's are already running 7800 RPMs...that's the redline on my 1994 348 Spider. The 348 Competizione's went to 9000...and I don't remember anyone claiming that they had different heads or valves.
I don't remember anything about my car ever being lean...I was struggling with a mis-behaving ECU causing me some problems, but I got it working pretty well and am now switching to a motec for a little more control than I had with the haltech. The other think is that a lean engine isn't too much air, it's too little fuel, adding fuel is as easy as a couple key strokes or a twist of the pressure regulator. Getting the air in is hard, and what this thread is all about Flow is a volumetric thing and air is compressible. What that means is that STP (standard temp and pressure) the head will flow say 100 CFM and at 15 psi boost the head will flow 100 CFM just like you suggest, but they are not the same cubic feet. At 15 psi there is about twice as may molecules in a cubic foot of air than there is at STP. So basically twice as much will flow through the same port in the same amount of time and twice as much will fit in the cylinder making the 3.4 liter perform like a 6.8 liter. Setting redline at 7800 and being able to fill the cylinder to 7800 are 2 very different things. A 348 does a better job up top than a 308/328 that have basically the same head. Thats due to a couple things. The 348 is EFI, not CIS, which flows better and the 348 has higher lift/longer duration cams. The head flow responds very well to the higher lift and the added duration gives the air more time to get into the cylinder. The problem is that to get the cylinders really full, the air needs to be moving fast through the port. With good port , intake and exhaust design, a street engine will have a volumetric efficiency of 110%-125%, basically supercharging itself. It does that by using the energy in the exhaust flow to start the intake charge moving into the cylinder while the piston is still going up. Then it uses the energy in the intake flow to keep the air moving into the cylinder after the piston starts going back up. But none of that works without good velocity. Increasing duration in the cams allows more time, and helps, but the air isnt moving faster so its limited. It also tends to make the torque peak move to a higher rpm while not moving the hp to a higher rpm, making the engine peaky or over cammed. The right answer is to make the intake, head and exhaust flow more efficiently. The factory 348 cam is still a bit low on lift, but has plenty of duration to feed the engine to 8500 once the flow is fixed up. The velocity on my QV heads is up about 30% over stock, so the head is flowing 30% more efficiently and the energy that was being wasted is now available to help fill the cylinder. What that will do is leave the torque peak at the same rpm it always was, but raise the peak hp rpm, making a more power and a less peaky engine with about 30% more hp and torque. Good heads let you make more hp with a flatter torque curve and run a lot less cam. Normally after proper porting you can pull out 15-20 degrees of cam duration for any given hp peak rpm making the torque peak to hp peak about 700-1000 rpm wider. Its all good. Again, Im not telling anyone what they should do to their engine and I don't know what was done 15 years ago, but by today's standards, the valves are much too small and the port inefficient
Would not the 348 cams need to be retarded/adjusted if one is going to run higher RPMs? I would think the factory cam timing would be set to take advantage of the lower rev limiter found in the production/street 348s. Example: the 355 cam timing is set for peak power at 8250 RPM with the rev limiter set at 8750 (though redline on the gauge is at 8500). So one could theoretically rev the motor more but not neccesarily get addtional power if one leaves the cam timing the same.
The rule is that higher rpm means you need more air and that means most flow (bigger ports and valve) and more duration in the cams. Increasing lobe separation angle helps low end and decreasing it helps up top, to a point. So retard the intake and advance the exhaust will do a bit better down low and vise versa up top. Lobe separations of 112-114 down low and 106-110 up top seem to work pretty well in general and will shift the peaks by maybe 500 rpm up or down. It doesn't work at well as a lower duration cam for low end or a higer duration cam for top end. At least that's what I've seem. I played with the cam timing on my engine on the dyno and the factory US spec made the most hp, the factory euro spec a bit less, but with a slightly wider power band. The difference is a 107 vs 109 lobe separation angle. With the blower I'm losing quite a bit of air out the exhaust at those LSAs and I'll probably goe to 112 or 114 this time to help ge the boost up, thinking an extra 5 psi will do more for me than the optimal LSA does. We'll see.
Okay, I'm working through the small stuff before tackling the fuel issue while listening to the discussions here. I got full throttle when I found that the chrome plate beside the accelerator peddle was interfering. I'm trying to figure out the fuel pressure regulators. Throttle off gives a shudder as does throttle on, most pronounced at low speeds. I think that's the regulator being opened by vacuum. There are no connections to any other devices on the manifold the regulator operates off of. Additionally, the vacuum manifold inside the air boxes have no outside connections. I suspect something else that would ordinarily be attached to these would soften the opening/closing of the regulators. ????? As for horsepower on the upper end, I can see only one answer as of now, and that's additional fuel. Keep in mind that nothing has been changed in the system but the throttle bodies and fuel pressure regulators. All other controls and sensors are factory. Since the regulators are closed under power (?), the only change is air, and it has to be more of it, therefore lean condition, requiring more fuel. Sooooo, the question is how to get more fuel to the motor, and how much. Chip change? Yes, probably so. How much? Whaddyathink? Fuel pressure? How to increase it with the current equipment? Is that a chip issue too relating to the fuel pump? Anybody know the answer?
Without knowing how much more air you have, it's hard to guess. Do you have access to an A/F meter you could borrow? That would make it pretty easy, just increase the injector time by the % you want to change to mixture. If you have to guess, 10% is a good place to start. To do it with fuel pressure, add an adjustable regulator and the new flow rate of fuel = old rate*log(new pres/old pres)...or just put it on a dyno and turn the pressure up until you get the A/F you're looking for. The problem is that turning up the fuel pressure will give you more fuel acroos the board,, not just up top.
Say you know what? We didn't check to see where the MAFS were set. I would think you could richen up the fuel a little bit by tweeking the screws on the MAFS, but you are gonna have to see where they are set first. If they aren't adjusted even then you are gonna have to set them up to the proper numbers, (383/ohms if I remember correct?). There is still alot of tuning that still needs to be done though.
Read post #166 you need something like this to start your guessing http://www.innovatemotorsports.com/products/lm1.php Mike he is still on 2 oem motronic ecus not consumer tuneable and no DAS available. So he needs to run thru rpm/load points monitor the A/F meter and ask ND to guess at % changes, then replace the EPROM chip and try again. ND has broken the motronic code and can burn chips for whatever he wants. This process will take a long time to get right without an aftermarket tune on the fly ECU or something like 2 of these piggyback fuel controlers http://www.powercardtuning.com/ Mike You post going from haltech to motec. You see this is my problem with aftermarket ECU's. The Haltech is a great system. Yet it is not good enough to run your car well. Only the higher level units are any good and our consumer level motecs are only $5000usd or so and these suck compared to real race units like the "EFI tech" ones for $20,000usd! The EFI units are used at the pro cart level etc... I am not sure if the sponcored competative pros are using the cheaper Motec M48's etc yet I see them in struggling lower level pro cars that no one knows about.
No point in running horsepower numbers now as it's clearly not in tune. By introducing so much more air, the fuel ratio has been altered beyond the capacity of the stock chip to change it. Mk e's solution is next, and then it should be meaningful with revised fuel delivery numbers on the chip.
More money gets you more stuff....but you don't always need it. 2 points, first my haltech was an early release and was recalled...which is why I got a "great" deal on it. Second my car is a little on the outer limits to use as an example. I'm certain I could get a haltech or electromotive to work just fine, but I went motec because I wanted the traction/launch control (because it's cool) and the other features were a nice bonus. A modern motec/haltech/electromotive are all a world better than the 15-20 year old OEM unit you have now. Honestly, even a MS II is better than the stock ECU, but hard to set-up. It's all relative too, an F1 car doesn't even think about a motec, but I know plenty of autocrossers that would die for a haltech ro even an MS. To this thread, it's easier and cheaper to change the chip and it'll run just fine, it will just take a few tries to get right. Chips make the most sense the the more stock it is. An aftermarket ECU lets you make as many changes as you want as fast as you can think you of them, and mess with things the OEM system doesn't have, but not everyone needs it or even wants it. My guess is that tuning the 348/355 would go much faster with an aftermarket ECU, but I don't think it's required, just faster.
I think a starting point was what ND said and disconnect the vacuum lines to the FPR's. Which may help in the lower RPM's (and its free). A chip with 10% more fuel from 4500 rpm on up will also help. As for fine tuning, A dyno run with a fuel mixture sensor should be the storyteller. Changing the engine/fuel managment system has always been an option, but that decision lies with the guy writing the checks.
Yep, gonna do the disconnect. I like the price. Chip ordered! Changing the fuel management system is a last resort. One of my goals is cheap horsepower!
It might take a couple of chip burns...but then every other 348 Brother can have the right chips for this mod without having to buy aftermarket ecus. On the fpr vacuum line disconnect...if that helps the lower rpms then it hints that we are in the ballpark on fuel delivery (just need chip tuning for more fuel, hopefully). On ernie's point about the MAF's...could be a very valid point when Plugzit is backing off of the gas (i.e. partial throttle), but the MAF's and O2's are ignored at wide open throttle. From reading this thread so far my impression is: 1. idle = OK after Plugzit did the ecu reset 2. WOT to 5000 RPMs runs the car like a scalded dog 3. any throttle above 5000 sees the car struggle 4. backing off of the throttle above 5000 sees lean backfire So I'm going to take the stock 2.5 chip from my OEM 1989 Mondial T binary and modify only the fuel tables...to see 10% more fuel from 4000 rpms up to the 7200 RPM redline. ...unless I hear otherwise from someone tonight.
Yes for anyone runnign a 2.5 motronic MAF start to work at 3/4 to WOT I'm pretty sure. Below that they just don't flow much If is runs like a scaled dog then we should get at least some teaser HorsePower numbers!! Don't keep us in suspence!
O.K....I guess i am just an idiot and don't get it. My understanding is a fuel curve is not linear. How can you just come up with a guess of above 4000rpm 10% increase with zero data? To me it seems like you are swinging a net in the lake hoping to catch fish. Sure it is cheap but geez this is crude. You know you could have bought a 350HiPo chevy crate motor for about the cost of the 355 throttle bodies....
Well maybe. The driveability of the old 20 yearold ECU is perfect and it is so clean on a california smog machine that it almost cleans the air. Drivability is where it is at and the old oem has it. After 20 years we can say it is totally durable too. We can't say that about your once great Haltech that left haltech as a good unit but now is recalled. Sure that can happen with OEM's but less so and oem have good warantee up to their 3yrs 40k miles or whatever. Look what happened to your haltech with the engine head in the 308 trunk. You see it is all part of a package...a system. The Oems spend huge dollars getting it right. It is very hard for some wrnech monkeys like us to improve on the OEM's compromises. I think it was you that told me MS2 did not have the steps? 8x8 tables or something needed to make a good street drivable system. So which is it? Is MS2 better than my 20 y/o ECU or what? I like MS2. It seems like a system a dummy like me can figure out. I really want it to work but I am lazy which is why I like the concept of OEM durability with an expendable piggyback fuel controler. It seems like the best of both worlds. There is no question that a properly functioning motec is better but getting it properly functioning and staying that way is an entirely different story.
Above 4000 RPMS I'm bumping up each OEM fuel datapoint by 10%. You are correct that this curve is not linear. It's dynamic. The ecu builds the fuel and ignition curves from battery voltage maps (the lower the voltage, the longer that the fuel injectors have to be open to obtain the same fuel injection), air temperature maps (this is from the hotwires inside the MAFs), coolant temp maps (retards ignition timing as your coolant temp increases), O2 feedback, etc...and this dynamic data is curved/sloped when you graph it based on Throttle position (AKA "load") and RPMs (AKA "Alpha"). He knows that he needs more fuel at and above 5000 rpms. Adding 10% to each point along the graph will get him more fuel. Yes, it's pretty crude. He's got to get to a wideband exhaust analyzer, but with his engine not really going beyond 5000 RPMs he needs more fuel to even be at the point for the wideband.
ND, This is all pretty cool. I don't need a wide band but I'm thinking of buying one just to play around with bolt-on's and chips you make. Can you tell from your maps what the oem is running for A/F ratio at WOT? Perhaps even at WOT the OEMs are set up for emissions thus a higher A/F ratio. If you can figure that out then there is a simple tweek with zero bolt-ons that can get you some power. For exmple I am running a challenge type tube exhaust. It has zero back pressure relative to stock and cats. so I expect to run lean but have no evidence of that. A wide band would tell me and if it is lean then you could tweek me. I actually doubt I am too lean because if it was all the challenge cars would have burnt up.
Crude, yes, but progress. Getting it in a zone where it runs pretty good at revs will make it a lot easier to tune up. We (at least I) am a novice at computer tuning and I'm using this as a learning experience. I want to make this as simple as possible, yet would rather spend time than money. Sure dyno time and shop time would shorten the process, but at ever increasing cost. It'll be a lot easier and cheaper to tune a car that's already "in the ballpark". I'll be glad to share the final results with everyone when I've got it as everyone's contributed. I've got two other cars I can drive in the meantime, and this one this running OK, just not competitive.
