I apologize up front if this has been talked to death but.... What is needed to substantially increase the rev limit of a 348 engine? Assuming you had a 348 engine in good mechanical condition laying around, what hard parts need to be upgraded to get to a reliable 9000 rpm? Are ti rods needed, or will the stockers hold together? Valves? Do the cams have enough duration to support it?
Just opinion here, but I've given it a lot of thought. The cams probably won't make hp up to 9k. The big mechanical limiting factor is valve train weight. The lifter buckets are very heavy.
There are a whole LOT of things that need to be upgrade in order for the f119 to spin at 9000rpm. Lots of head work will be needed to supply the amount of air the engine will demand at that rpm. You will need different valves, different springs, shim under bucket followers, guides, retainers, and properly ported ports. Next you'll need custom cams. The stock cams make peak torque at around 6000rpm and simply DIE after 7000rpm. I have seen this first hand over many dyno pulls I have done on my car. The lift and duration of the stock cams simply will NOT support 9000rpm. The stock fuel injectors get tapped out FAST with any kind of serious mods. Then there is the issue of fuel pressure, fuel supply lines, and the pumps, in addition to the injectors only being 18.4/lb units. At 9000rpm the engine will want a garden hose, and the stock injectors at best would be squirt guns The stock intake tubes, air box, throttle bodies, plenums, and runners will need to be modified, or completely ditched and replaced with individual throttle bodies. When you have an 85mm piston trying to pull air through a 54mm throttle body you are going to have some serious breathing problems at 9 grand. Then there is the bottom end. The stock crank is pretty stout and can handle 9000+rpm. However, the rods, rod bolts, and crank bolts will need to be upgraded, as well as the rings and wrist pins. Then there is the Motronic 2.7 ECU. You will either have to crack the rev limiter, or go to a stand alone ECU, which will also entail a custom wiring harness. That is just a general idea of what it will take, and there's even more to it than that. It can, and has been done, it just takes money.
Easiest/cheapest way would be to sell the 348 and buy a 355. That will get you 8750rpm without any work. Then get some custom chips if you really want that extra 250rpms.
Very informative in short many problems. I suspect our 355 s are similar if we wanted 10500 rpm out of them.
Not really, they solved a lot of the problems. You'd likely just need valve springs and change the cam timing to get to 10500rpm in a 355.
I don't know about that... I love my 355 it wants to rev and rev but I've had multiple people with supposedly first hand knowledge say a stock 355 will not live at 9000 reliably. Again, the question is this: You have a 348 engine laying around, what is needed? Not what is easier, not what is more popular. I know the 355 is an eaiser way, just like the 360 is easier still. I know the electronics won't handle it, along with the intake. Those are already in the works. I'm looking for first hand, seen it yourself information. I am on an honest budget and and going to use a 348 engine to see what I can get out of it. Just trying not to make it go pop instantly is all.
Talk to Ernie and a few others they have tried various mods. I think Ernie's post sums it up pretty well.
Fchatter "Time" owns the LeMans engine, built by Simpson. Dave Helms owns a couple of serious hotrod engines built by the factory (or Michelotto?). Bigger valves, lighter lifters, better springs, cams that won't idle needing relief in the heads for lift. Cosworth pistons, strong rods. O-ringed heads. Cambelt support. Time's has individual throttle bodies, Dave's the Euro plenum. Both need Motec engine management at a minimum. Yagottaremember, Ferrari doesn't leave a lot on the table. You're talking +20% in revs, so serious rebuilding is called for. It'll be an epic project, but one that'll make you famous, for good or bad. There's not much horsepower to be gained by working around at the periphery as most of us poor guys do. Be my personal hero. DO IT!!!!!!!!!!!!!!
Forgot two things. The intake trumpets will need to be 1.3 inches shorter to move the intake resonance up to 8200 RPMs. Thus some machining of the intake system will be on the table. The headers will need to be shortened (about 3 inches) to move the header resonance up into the 8000 range. I also suspect to make good power up there you will want 1+7/8 tubes 28" long. Now packaging this is a lot bigger headache than some of what Ernie mentions. In order that the motor actually makes power up there.
For a 348 engine, what do you call substantial? Our fuel cut offs are at 7750. There are performance chips tuned to 8000 rpm cut offs. How much higher do you want to go? If you are talking 355 territory, or about 8500/8750, then we are a bit short on engine management. Without doing too much you could get the engine to spin that high, but it might not make that much power up there because cam grind is limited. So you do custom cams, then the valve train needs upgrading. Remember 348's use solid lifters; 355's use hydraulics. Wish that we could adapt those to our engines - hah! Fuel intake becomes a limit at WOT when pushing that rev range. What the heck, you might as well do some head work and increase valve size. Before you know it, you have hit astronomical expenditures that would probably best serve you by buying another car. Or, you might figure out a 355 engine/trans swap. Or turbo charge it. Heck, blast it with NOS. I was discussing this with Time/DeeGee and we noted this is not like hot rodding a Chevy with all its incredible variations of each engine they've made over the years. Heck, the 350 cu V-8 has so many alternatives inventers were able to come up with the widely popular 383 derivation pretty much using stock parts. Not something Ferrari shares with Chevy. You want a V-8 in 1990, well here it is, our 3.4 liter. Oh, by the way, it isn't related to the previous 3.2 or the later 3.5 so you are on your own. But, man do we like the challenge!
So what is the goal of the extra RPM? Can it be achieved some other way? Often times it can. For example, some want to go longer between shifts - a different rear end ratio can accomplish that (so can tire height to some limited extent). Do you want more power? RPM is one way there, but not the only way there. It's one thing to want a motor that rev's into the stratosphere because it sounds cool, it's another to have a purpose behind the rev increase. Coolness factor, that's going to cost a bucket of money for arguably little gain. It would be cheaper and easier to put a 355 motor and transmission in there than to build a Ferrari 348 motor ground up to handle 9k RPM. It would be cheaper still to put a 3 rotor RX-7 motor in there with a turbo and rev to 11000 RPM (It would also be sacrilegious). So I guess my big curiosity is why? Mark
Actually, it'd probably be cheaper to start with a 355 and add 348 strakes, 348 front bumper, and disconnect the power steering (if one wants the 348 steering feel). Not that anyone would want to do that but just saying.
