| Author | Message | ||
| Matt Morgan (Kermit)
Junior Member Username: Kermit Post Number: 133 Registered: 8-2001 |
Yes Ernie I have ported them, unfortunately, as I often get the cylinder heads only, I don't get a chance to dyno them. They are, from my experience, a better flowing head, and the valves are slightly larger, which is helpfull when "feeding " a larger motor | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 690 Registered: 11-2001 |
Kermit Haven't you done some porting and polishing of 348 heads? What HP gain have you seen from this on the 348 engine. Also, if the compression ratio was raised to 11/1 how much of a gain would you see? | ||
| Matt Morgan (Kermit)
Junior Member Username: Kermit Post Number: 132 Registered: 8-2001 |
I have been looking at this issue for a long time now, from the 308 standpoint. The following is what I have found so far, and it hopefully will give some insights. I have slid a 348 head onto a Quattro block, so logically, I believe the bore centerlines are the same. A 308 can be bored to 83mm, with the stock(cast iron) sleeves, for a This leaves .159" wall, which just squeaks under what Darton Sleeves recommends as a minimum of .150". To go larger, special sleeves would have to be built that are a larger diameter of course. The problem this creates is coolant flow, as they are tight in a stock configuration. While I haven't gotten together with Darton on this yet,it may be possible to go out to 86mm by surface grinding (very precise) the sleeves so that they actually contact, and somewhat support each other. By slotting them with a Ball Nose end mill, which leaves a rounded cut, it MAY be possible to provide enough coolant flow to get by. IMO, it's dicey whether or not there will be enough stiffness in the walls, particularly where they meet, to seal well. One problem that may occur is one cylinder flexing a bit will cause distortion in the next, due to them touching. If it can be done, the result would be an oversquare motor of 3.3 litres.with the 75mm sroke, 3.5 litres On the stroking issue, if it was possible to find out the crank alloy, and it IS weldable, it may be possible to offset grind it to perhaps 77mm stroke, it should turn out to about 3.6 litres, hardly worth the effort. The overall cost of crank workover, and as Ben mentioned, the piston issue,loks to me not to crunch out well on a dollar per horse value. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 499 Registered: 5-2002 |
I'm honestly not sure, the guys at Norwood would know. There's a guy, Jeff Edison I think, that has a twin turbo with an intercooler that make 550HP, so that would be about 12-15 psi, but I don't know if the CR is stock. 5-6 should be fine, and about 35%-40% more HP, so 400-420. You might get away with more, Jeff or norwood would be the ones to ask. | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 680 Registered: 11-2001 |
Being that the current compression is 10.4/1, how much boost could be used with out granading the motor? | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 498 Registered: 5-2002 |
Ernie, An inch is all you really need, 1.5 will get it do comfortably. So it can be done. To make 500 hp you will also need an intercooler, 400 to maybe 450 I think you could live without one. You will also need a programable ECU (haltech,electromotive, ect), bigger injectors, presure regulator, throttle body and a few other goodies, plan on spending 6k-8k on parts and a few k more to get it installed. It would be fast. | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 674 Registered: 11-2001 |
Mark, at the very most, there is two inches from the back of the firewall to the front of the engine. I don't have a digital cam so I can't get you any pics. How ever there have been post of 348 engine bays. 500, force fed, horse power sounds really nice. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 497 Registered: 5-2002 |
>> So all it is, is just making the engine able to suck in and blow out more air. << Yes, that is exactly right. Build a better pump, make more HP, that's all there is to it. A quote from an engine builder I've always liked is "I don't care if your Jesus Christ himself, without air you aren't going to make HP" >> On a side note, about supercharging a 348. There is almost no room at the front of the engine bay. So would a roots or centrifical type even be possible?<< How much is almost nothing? Can you snap a pic of it? I've never looked close enough to know. You might be right though, a turbo or 2 may be your only real choice. | ||
| BretM (Bretm)
Advanced Member Username: Bretm Post Number: 3395 Registered: 2-2001 |
Not to be too much of a nitpicker, but the bore stayed the same between the 348, 355, and 360, the stroke is what grew. Another reason most companies stroke over boring is what Mark brought up briefly, increasing stroke increases the overall engine size less than increasing bore (let's say you go 2mm longer stroke, the engine is all things being equal only 2mm taller). If you make the bore larger, everything being equal the engine just grew 2mm x 4, or 2mm x 6. It's usually easier to fit a 2mm higher engine in the same space than it is a 1cm longer one. This has more to do with initial production though. And likewise Mark, I'm stilling looking for a ride in that whistling rocket you're building up there. | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 662 Registered: 11-2001 |
Mark, thank you. That was exactly the answer I was looking for. So all it is, is just making the engine able to suck in and blow out more air. On a side note, about supercharging a 348. There is almost no room at the front of the engine bay. So would a roots or centrifical type even be possible? | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 495 Registered: 5-2002 |
<<why>> That is a really good question with no simple answer. Often it comes down to the factory wants to reuse some or all the tooling the already own or minimize the number of components that get changed. Or it may be a question of what will fit in the car, making the bore bigger makes a longer engine, longer stroke makes the engine taller. For ultimate performance (hp/liter) a bore to stroke ratio for 2.2 +/- seems to be preferred, but for all around across the board a ratio much closer to 1 is preferred. Engines are built everywhere from about 0.5 (trucks) to 2.5 (some sport bikes). It�s a compromise. HP = torque x rpm / 5250, so you can make more by increasing torque, which depends on displacement and your ability to fill the cylinder, or you can make the same torque and spin it faster. Either way you need to flow more air, so bigger cams or bigger valve are needed or both. Bigger cams will not work properly at low rpm unless you increase the compression ratio. Increasing stroke or rpm increase the loads on the bottom end, so you need to lighten things to keep it safe (Ti rods). Bigger cams or bigger valves or higher rpm increase the loads on the valve train, so you need to lighten or put in stronger springs. Ferrari did al those things when they went from 3.4 to 3.6 and increase the redline. Simply increasing you displacement from 3.4 to 3.6 won�t give you any more hp unless you also increase the flow (cams or porting or both, exhaust, �), it will just shift the peak to a slightly lower rpm. It�s only 6% of the difference between a 348s hp and a 360s. But to finally get more to the point of your question, increasing you displacement from 3.4 to 3.6 by increasing bore will make 1 or 2 more hp at a few rpm more than doing it with stroke, but it�s probably easier to do it with stroke. Bret, I�m still hoping to get a ride it that when you done. I think I�m still 4-6 weeks out on mine. | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 659 Registered: 11-2001 |
Well the reason I asked what I did is cause of two things. The first was that when I was looking at the engine specs between the 348,355,and 360, the stroke stayed the same. The bore was what was changed on the 355 and the compression was upped to 11/1. Then for the 360 they did the same again, the stroke stayed the same and they increased the bore. They also added another valve for more air, to both engines, but that wasn't what I was asking. The second reason that I asked was I was reading about the Prodrive 550. They also increased the bore to get more power out of thier engine. So I was wondering from an engineering point of veiw which one would be better. Why is it that some will increase the bore while others will lengthen the stroke to again more displacement, and more power. | ||
| BretM (Bretm)
Advanced Member Username: Bretm Post Number: 3387 Registered: 2-2001 |
Hey Mark, getting there with it. I finished with the engine itself last weekend so now just have to rebuild the diff and then I can put the block on the oil pan and get the rest of it together. Starting to see the light at the end of the tunnel, especially since I'll be out of school for the summer in a week. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 494 Registered: 5-2002 |
Ernie, I think you might be telling yourself what you what hear. I have never seen a bolt-on (air filter/exhaust/chip)348 beat 320. If you think about it, 360 is a 20% increase. The stock injectors are sized to make 300 HP at about 85% duty cycle, they just won't flow 360 HP worth of fuel unless raise the rail pressure to 60 or 80 psi, no chip can make that happen. A 360 engine spins almost 9000 and makes 105 hp/liter, if you do what they do (bigger cam, better flow, compression, Ti rods) that only gets you to 357. Your not going to do it with a chip. 400 HP is a full race prep with about a 5k mile life. Bret, Is your engine ready yet? Mines not  | ||
| BretM (Bretm)
Advanced Member Username: Bretm Post Number: 3383 Registered: 2-2001 |
Just buy a 355, you'll be ahead in the long run. Ti con rods are gonna run you at least $4-5G from here in the states, if you want Italian stuff you're talking like $6-7G. To bore or stroke is gonna be a lot. You're gonna need liners, the machine work on your block to fit the new liners, pistons, etc. Then you're gonna have to dry build the engine and check with clay most likely. Pull it all apart again. Then throw on a $1500 gasket set, bearings, custom head gaskets. If you're looking to lighten up the best place to start is the flywheel/clutch but it's not necessarily cheap. Best thing to do to a 348 would be see if DigiTec can work with the stock ECU and larger injectors, then do a set of 11:1 pistons (stock is 10.4:1), porting, regrind the cams, maybe do a different clutch/flywheel. Then enjoy. Even doing that you're gonna spend more than it seems. Anything more than a project like that and you would be better off just trading in for a 355. I would talk to Kermit, he's out there on the left coast with you and is an excellent source for getting hp and is very reasonable with prices. The dealerships are gonna be pretty much useless. He's also who you would want to talk to about porting the intake and exhaust tracts. | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 652 Registered: 11-2001 |
Ok so increasing the stroke is out. But I'm not convinced on the bore yet. I think you could get some more ponies out of it if it was taken from 3.4 to lets say 3.5, and if possible 3.6. Also I would change the connecting rods to Titianium. Reduced weight and more strength. The 348's put out 300hp already. I have seen numbers for 348's that are chipped with the exhaust and filter in the 350-360hp range. So I think 400hp could be accomplished without force feeding it. Yes fellas I am aware that it isn't cheap to rebuild the motor. Is anything cheap on these cars. So I figured when the time comes that the engine has to be opened up, why not make it better. I really feel there is untapped power in it. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 492 Registered: 5-2002 |
You probably can't gain enough displacement with either bore or stroke on a ferrari engine to make the HP gain worth the money you�ll spend. For $10k-$15K you could ring about 320-350 HP with cams/pistons/porting/ect. Or for add a turbo or blower for the same money and look at 400-600. | ||
| Philip Airey (Pma1010)
Junior Member Username: Pma1010 Post Number: 225 Registered: 7-2002 |
Ernie At the risk of teasing an old topic, if the OEM crank is machined from a billet, you are going to be looking at very large $ for how much gain? | ||
| Ben Millermon (Brainsboy)
Member Username: Brainsboy Post Number: 294 Registered: 5-2001 |
I agree with jack, Also you may have a longevity problem with stroking too. Although my experience is with american race motors, the theory is the same. Sometimes with stoking you need a longer rod which makes for a shorter piston with less skirt area to support it, causing more wear. They tend to have less life then other motors from what I have seen. | ||
| Jack Habits (Ferraristuff)
Member Username: Ferraristuff Post Number: 382 Registered: 4-2003 |
That's usually a matter of finances... Boring it out only requires the boring + suitable pistons. Stroking it requires a new / modified crankshaft which is BIG $$$.... Don't foget that "simply" increasing displacement might not bring the gain that you're looking for as it requires adjusted inlet tracts, carbs, possibly valves and everything has to be "in tune" with eachother. Jack | ||
| Ernie (Ernie)
Member Username: Ernie Post Number: 646 Registered: 11-2001 |
I was sitting thinking about my car, and figured out that eventually the engine is gonna have to be rebuilt, at some point in the distant future. When this time finally comes, I wanna get more power out of it. Now I already know about chipping it, filters, exhaust, porting the heads and intake, even turboing or supercharging it. I would like to keep it N/A, so we all know displacement in the name of the game to getting more power. This leads to my question. To get more power by increasing the displacement, when is it better to have more bore, and when is it better to have more stroke? Also which will yeild better results? |