Ya, fascinating stuff. Get it put back together for our sake! ;)
Huh???? How do you figure? The stock intake valves are minuscule, 30.5mm. CFM jumped from 209, @ .360 lift, up to 241cfm at the same lift with the 34mm intake valves. The stock 348 cams don't have all the high of lift .362" and 227º duration. So you need it to flow more air with such a low lift, which the 34mm valves allow it to do. It can't make power it if can't breath. On a Honda PR3 head, off a B18C, the intake cams have a .417 lift and 230º duration, using 33mm intake valves on a US spec heads. The type R cams are much more aggressive, .453" lift and 240º of duration. I have heard of race prepped pr3 heads flowing 300+cfm (@ probably .500" of lift) using 34mm intake valves. You won't be able to run cams that crazy on a street car though. In my opinion I think the 34mm intake cams are needed to get the f119 head to breath the way in needs and wants to breath, especially with the stock cams. At a bare MINIMUM they need to be at LEAST 33mm. The cams also need to be upgraded = more money + stand alone ecu. But that is just my opinion.
After heads, maybe you should try the "375" intake: https://www.ferrarichat.com/forum/threads/the-naturally-aspirated-400-hp-348-yes-for-real.511097/
Here's why. There isn't enough meat in the heads for you to easily ream the intake valves out that much. You need new seats and it may even then not fit right. I'm measuring like about 1mm diameter increase with the stock seats. Go higher and you run the risk of dislodging a seat and dropping a valve. So you need new seats. Can do, but really expensive. I am not doing this. I am putting this money elsewhere, like the engine management system. My priority has always been to wring out as much extra power from this engine as I can but make it smog legal, appear stock and do not compromise reliability. I leave pushing the envelope, and the boundaries of your wallet, to you.
adapt or die...everyone is getting blown. The death of the mustang V6 for the ecoboost 4 and the dual phase BMW turbos and 488gtb are examples of the trajectory of the future. It is way less headache with less "engine build" drama to get blown.
Blower or twin turbo for efficiency for sure Turbo sounds OK NA sounds great Blown can sound amazing Crap I hate you now I need blower
Don't forget getting blown you can just about pick your horsepower addition. With big valves and giant cam you just guess without some data and your guesstimated internal parts compatibility throw your reliability right out the window. So Tim... go get blown...
Yeah just make sure your heads are nice flat and some nice new studs and go to town. I have my diesel apart now doing that
Personally I like the characteristics of a naturally aspirated engine, on this car. I've had turbo and supercharged cars. Fun but would never want a forced induction F355 or 348 myself.
Pfffftttt, Big whoop! Just put in bigger seats. It's done all the time in the import tuning scene, with their engines turning 9k-10k all day long, and no dropped seats. So it's a few extra bucks, no biggie. If I'm gonna tear into it that far I'm not gonna wuss out with only going 1mm over = a waste of time and money. May as well not even bother. I am 100% in agreement with you on the engine management. The stock ecu's are way outdated, and slow. Plus to fully realize any serious mods you need to be able to EASILY tune for the modifications = 21st Century ECU. As for the smog mumbojumbo, you do realize that there are 49 other states in this country. You don't have to remain in the 1 State that has the harshest laws against improving a vehical's a performance.
Feel free to spend the extra cash. It's like $2K difference. So I'm out. I will put it elsewhere. I'm having some flow work done as well. Secret stuff. Remember stock, smog legal, reliable are my guidelines.
Well be sure to update us with your before and after flow numbers. Plus the before and after dyno numbers.
Just for kicks I found an online calculator for estimating power based on cfm, displacement, and number of cylinders. I then plugged in the flow bench numbers TheItalianJob got on his head. F119 V8 c.d.i. = 207 Stock 30.5mm intake valves = 209 cfm @ 28" of water Estimated stock power potential = 396hp (which also shows how choked off the factory intake system is) F119 V8 c.d.i = 207 1mm larger intake valve, 31.5mm = 222 cfm @ 28" of water Estimated power potential = 421hp F119 V8 c.d.i. = 207 New 34mm intake valves = 241 cfm @ 28" of water Estimated new power potential = 457hp Stock = restricted breathing -hp with proper breathing +1mm = potential increase of +25hp over stock +3.5mm = potential increase of +61hp over stock, AND +36hp over the "Cali friendly" increase. This of corse is also dependent on the intake system being able to allow the engine to breath. So I also decide to run the numbers for the ported intake bolted on the 34mm head (232cfm) = 440hp (+19hp over the 1mm bigger valve). No brainer here. I'm spending the extra coin and going with bigger valves.
Hey great story here, I too am in the middle of tearing down my 348 this winter. I was going to do the basic major service plus a few other items but noticed during the leak down test that I had a bit of sharing between 6 and 7. So the heads are on their way off. Question for you .... : I also bought the special head removal tool to gain access to the hidden acorn nuts. But low and behold the tool does not reach in as it should, it bumps into the casting on at least 8 of the 20 bolts. I spoke with the manufacturer and they said it is normal for these heads to have variations, and that just a bit of "fettling" (grinding) here and there would do it. Did you have the same problem. Here is a pic of my engine sitting and waiting for me to continue. Image Unavailable, Please Login
So yesterday I had the opportunity to discuss larger valves with someone, and it just so happened that a F119 head was available to measure. In particular we measured the seats. The stock intake seats where 33mm. Meaning you could increase the intake valve size up to 32mm, and still have 1mm left without needing to put in new seats. That is an increase of +1.5mm over the stock intake vale size. There was also plenty of room to put in new larger seats to accommodate larger valves, as Daniel has already shown. If you don’t wanna spend the coin on bigger seats at least put in 32mm intake valves, because the stock seats can support them. Plus you if get an excellent 3-angle, or radius job put on the valves that will also help the breathing.
Ernie have you taken a high reving engine to within 0.5 mm of the edge of the seat. I have gone close but not that close. My own personal opinion would be to not take it that close but instead take the first radius on a three angle seat close to this and then widen the main seat. This would help dissapate the heat more. I was all ways worried if I got that close I would start burning the valves along that small first radius. I was not building an engine for the street at the time and for the few seconds you could get on it, on the streets it would likely be ok. The track is where i was worried.
No I haven’t. When the day comes for my head it’s getting new seats and new larger valves, that will be at minum 33mm on the intake. I’m not monkeying around with the stock seats.
