[duck.co.za]

Hi, have you ever driven a 250 or 275? They rev fantastic,have you driven a 330,they rumble rev,they dont zip. A 365 has a better rip than a 330. My point is stroking Ferrari engines is the wrong way to go. Bigger bores gives more zip in the revs and stroking makes them rumble. I want 3.3 litres and lite crank & titianium rods with a big bore for high end HP.I would like to ask the pros what is the largest bore possible on 308s?

I think it all boils down to cost !!!! The dayton liners/block machining is very expensive ?? I stand corrected , but I think they get the bore out to 89mm ?? ( Nicks engine )
Johns is the best option to dollars spent ?

 

[ferraripilot]

Hi, have you ever driven a 250 or 275? They rev fantastic,have you driven a 330,they rumble rev,they dont zip. A 365 has a better rip than a 330. My point is stroking Ferrari engines is the wrong way to go. Bigger bores gives more zip in the revs and stroking makes them rumble. I want 3.3 litres and lite crank & titianium rods with a big bore for high end HP.I would like to ask the pros what is the largest bore possible on 308s?

Ferrari has already done the engineering on this one. The 79mm stroke of the 360 crank vs the 71mm 308 will not make a difference regarding how it will rev. The 360 revs to 9k+ due to having Ti rods, so 8k with steel rods is no problem. Also, the 360 crank is far lighter which will aid in willingness to rev even further. Carobu has built a few motors like this now with peak power being well into the upper 7k range.


And yes, the 360 rod and main journals are the same. The rod small end however is 20mm rather than the 308 18.5mm.

 

[tazandjan]

Funny about titanium connecting rods. Ferrari had them on the 550, but they broke regularly on the LeMans cars, so they switched to stronger steel rods and carried that over to the 575M. Surprizingly,the steel rods are more expensive than the titanium rods. Titanium is not always the Holy Grail, just like sodium filled exhaust valves. Funnily enough, Chevrolet has made both work with no problems on the C6 Z06 engines, but the redline on those is only 7000 rpm.

Ferrari sleeved the block for the 208 and 208 Turbo cars available in Europe for tax purposes. Redline is the same on those undersquare (long stroke, small bore) engines as it is on the normal 308s.

 

[bobzdar]

Funny about titanium connecting rods. Ferrari had them on the 550, but they broke regularly on the LeMans cars, so they switched to stronger steel rods and carried that over to the 575M. Surprizingly,the steel rods are more expensive than the titanium rods. Titanium is not always the Holy Grail, just like sodium filled exhaust valves. Funnily enough, Chevrolet has made both work with no problems on the C6 Z06 engines, but the redline on those is only 7000 rpm.

Ferrari sleeved the block for the 208 and 208 Turbo cars available in Europe for tax purposes. Redline is the same on those undersquare (long stroke, small bore) engines as it is on the normal 308s.

I think rod/stroke ratio is far more important when trying to rev. Just go with the biggest bore possible, no downside. Too much stroke without increasing the rod length and your piston acceleration goes up, dwell time decreases and side loading will go up. You end up having a harder time revving due to increased friction and the more violent intake/exhaust events. I'm not a fan of 'strokers' unless you can maintain correct geometry in the bottom end, but to each their own. It doesn't look like this case will cause any issues but it's something to watch out for as bigger isn't always better.

 

[duck.co.za]

I think rod/stroke ratio is far more important when trying to rev. Just go with the biggest bore possible, no downside. Too much stroke without increasing the rod length and your piston acceleration goes up, dwell time decreases and side loading will go up. You end up having a harder time revving due to increased friction and the more violent intake/exhaust events. I'm not a fan of 'strokers' unless you can maintain correct geometry in the bottom end, but to each their own. It doesn't look like this case will cause any issues but it's something to watch out for as bigger isn't always better.

Interesting , Ferrari kept the same rod length from the 71mm 308 stroke all the way to the 360 at 79mm ?

 

[bobzdar]

Double post

 

[bobzdar]

Interesting , Ferrari kept the same rod length from the 71mm 308 stroke all the way to the 360 at 79mm ?

What's the change in rod/stroke ratio? I think going from 308 to 360 stroke, the bigger change will be in cam timing than anything else. Calculate the peak piston acceleration and average piston speed, you'll find they go up quite a bit with the longer stroke even if you don't rev any higher. What it boils down to is that you end up with the same average piston speed and acceleration as if you just revved the 308 higher, so won't gain any power unless you're at a valvetrain limit (which may be the case here). It made sense for ferrari as they were already at 9k rpm, so the only way to get more air into the engine is to increase displacement unless they radically altered the valvetrain to spin it even higher. Then you also have problems with idle emissions due to the cam profiles needed to rev that high, etc. They had to ditch the traditional 8 when they went to the 430 for those very reasons.

My point was just to be careful in thinking bigger is always better. For bore, I don't see any downsides, but the stroke can cause issues and at a certain point will hurt your top end power due to the added friction etc. Where that is on a 308/328/348/355/360 build, I don't know, I was responding more to the bore/stroke question in that it doesn't affect rev ability much outside of the issue that a small bore will hurt breathing. Not as much of an issue on a forced induction engine (208), so ferraris decision there was likely due to ease of manufacture as all they had to do was drop in different liners and pistons instead of doing a crank and pistons to get down to 2 liters. That's all kind of off topic to this thread anyway, but fun to think about.

 

[tazandjan]

Bob- You are oversimplifying very complex topics.

 

[bobzdar]

Bob- You are oversimplifying very complex topics.

Very true, but the post was long enough and it doesn't really pertain to this build.

 

[ferraripilot]

Very true, but the post was long enough and it doesn't really pertain to this build.

That's what I got out of it. Great post regardless though. Average piston speed on this build is not going up but maybe 4-5%. If I were stroking the engine to an oversquare configuration and adding some 20mm of stroke then there would be cause for concern and a rethink of rev limits and the like. For this case, Ferrari seems to have already done all the work in deciding the stoke rod length is adequate for 79mm stroke.

I believe Nick is building -and has been for quite some time- a 89mm x 79mm 308 engine. Steve has the block which I believe has already been sleeved.

 

[bobzdar]

That's what I got out of it. Great post regardless though. Average piston speed on this build is not going up but maybe 4-5%. If I were stroking the engine to an oversquare configuration and adding some 20mm of stroke then there would be cause for concern and a rethink of rev limits and the like. For this case, Ferrari seems to have already done all the work in deciding the stoke rod length is adequate for 79mm stroke.

I believe Nick is building -and has been for quite some time- a 89mm x 79mm 308 engine. Steve has the block which I believe has already been sleeved.

The only thing you may want to look it is the cam phasing as smaller rod/stroke ratio may want a little wider lobe separation to give the exhaust gasses a chance to get out and not contaminate the intake charge given everything else the same (this is theoretical, I haven't played with your particular combo and don't know how the stroke change will interact with the port). A good engine sim may be able to help there, but more than likely you won't know what is best without dyno testing. So, if there's a recommended lobe separation for use in a stock 308 or 328 stroke configuration for those cams, maybe widening 2-4 degrees will give some higher rpm gains? Just something to look at, and you may already have planned to do some dyno tuning of the cam timing anyway. I love this kind of project.

 

[Kaos Andy]

New here, really like the build and detailed info. I am a BMW tech by trade so very interesting.
I really like the 308 body style, so why not a 355 or 360 engine and trans complete?
I really like a north/south mounted engine.

 

[mk e]

I believe Nick is building -and has been for quite some time- a 89mm x 79mm 308 engine. Steve has the block which I believe has already been sleeved.

I've only heard of 1 of those engines and last I heard it hadn't run yet. Nick's car is a 3.5 with I think 89mm bore but stock 71mm stroke....I think

Either way I'm sure it will be a nice engine you're putting together

 

[tazandjan]

Andrew- There have been a few 308s converted to be 288 GTO look-a-likes, and a couple of those did go with a N-S engine orientation like the original. Makes it more difficult to do a belt change, though, and the 348 and F355 are engine-out for major service. The 360 has a removable panel to do the belt changes.

Major surgery. Mark's V12 in a 308 is major enough, and it is still a sidewinder.

 

[reggazz312t]

Flowbenched heads

FerrariPilot,thanks for sharing and answering questions. Could you quick update on your heads? I know you have trick valves,did you port? Thanks

 

[JazzyO]

Hi, have you ever driven a 250 or 275? They rev fantastic,have you driven a 330,they rumble rev,they dont zip. A 365 has a better rip than a 330.

Based on my own cars I have to disagree with that. My 330 really flies through the rev range now that the carbs have been refurbished. My 365 Boxer does not rip better than the 330, they are equals. I do agree that the 275 is a bit zippier and less torquey than either the 330 and 365 but the difference is not massive.


Onno

 

[ferraripilot]

FerrariPilot,thanks for sharing and answering questions. Could you quick update on your heads? I know you have trick valves,did you port? Thanks

I opened the intake valve seat ID by installing seats with about 1mm larger ID and a slightly larger OD. I then ported the port area into the bowl and blended it through the guide and throat area. The short side radius was smoothed a bit as well. The type of valve is almost more important than the diameter of the valve itself. I used a nailhead style valve as opposed to the stock tulip style valve which sucks up a ton of the volume in the bowl. The nailhead valve I used has an additional back cut which aids in low lift while the nailhead really showed improvement in lift over .150.

 

[reggazz312t]

330s rev much nicer than boxer 12s

Pressed hard in upper gears 330s sound and feel heroic,I had p6 cams on 9679 and 365 DFIs on all 3,and 2 other GTC. Just Fantastic Cars today and 30yrs ago they were like 430 are today,untouchable.Flat 12s rumble and theres not much zip but a lot of MPH in little time.I had a 400A and that engine was very nice reving,much more turbine like than TR/BB. Dont get me wrong I love all of them.I thank FerrariPilot and his Car is gonna rip. 275s cost a lot more than 330s and why is that?

 

[ferraripilot]

I'm replacing the 1, 2, and 3rd gear synchros and probably a couple needle bearings. I'll post pics once I have the thing apart. Synchros came in today so I guess that's step 1 right

 

[bretm]

...Synchros came in today so I guess that's step 1 right

Nice. Looking forward to the pics. How much do synchros cost for the 308? Are there any cross references that you found, or is it a dealer/Ricambi/GT Car Parts sort of deal?