308GT4 Liners and Pistons

I recommend using Ross racing pistons as well. Their wait time is shorter than JE and the piston to wall clearance they allow for nowadays is the same as JE. In the past, Ross had to have greater piston to wall clearances due to Ross not quite mastering their manufacturing designs yet. Ross also uses a slightly harder style aluminum which I think will last longer. Just an opinion.

REgarding your cylinder liners, I am not sure why you would need to replace them. Are they that bad?

Compression is completely up to you. Keep in mind that if you change compression, you are going to have to re-tune those carbs which can be quite a process, but if you are into these things as I am, it will be well worth it. My understanding is that the carb cars respond very well to higher compression.

 

I'm pretty sure the 79's did not have Nikasil liners, so you can just hone them and use them, unless they are THAT bad.

OEM liners are $306 US EACH. I'd want to be really sure you need to replace them....

 

You can't order the pistons until you have precise measurements first.

Cylinder bores need to be carefully "miked" by someone who knows what they are doing. You need to know what you have (out of round, tapered?) before you can decide whether they are usable. If you are replacing pistons you want a "like new" fit with the bores. It might be feasible to bore the liners to the first oversize, maybe not. If you bore the liners, you need the pistons first so they can be "fitted".

If you buy both pistons and liners, verify the clearance before you use them (even if they are OEM). Don't forget to check ring clearances and end-gaps.

Resist the temptation to just hone the old bores and slap in new pistons unless they are nearly perfect.

It is important to get all the honing grit out before you put it together. This can only be acheived with "soap & water". Brake cleaner or parts washer solvent won't get it all and you'll be contaminating your motor before you ever start it.

 

you dont need new liners most people bore from 81 mm to 82 mm and replace with JE pistons.

If you have a torque plate you dont even need to take the liners out just bore in situe.

 

I have even heard of situations with well used 308 short blocks where the only thing the liners needed was a simple dimple honing so the new rings would seat well. On many occasions I have heard of hone marks still being very visible upon teardown. 911 sc motors and 911 3.2 motors are the same way. 308s have very robust short blocks. That being so. Still have someone who knows what they are doing with a mic measure them well and thoroughly. However if the engine had a good service history, and was generally not abused, I would not be at all surprised if you needed stock size pistons or were even able to reuse the old ones.

 

I would not simply take "off the shelf" aftermarket pistons and throw them in, not on one of these engines. Anything Ferrari had or sold would be one matter, such as Borgos, but you should really check things carefully when going aftermarket. The engines might all be physically the same, but the piston manufacture really would like the numbers to make sure they build you the right stuff. Even if they dont, you should want to for your own peace of mind. They generally want the CC of the combustion chamber, the cylinder head volume, the dome volume of the piston, the compression height, head gasket volume, the wrist pin bore height and offset, rod length, deck height, and stroke length. In addition, they may want valve overlap clearance at +010* and -010* TDC, or some other figure. Its meticulous work, and one miscalculation can be truly disastrous. You could have engine damaging high compression, anemicly low, or you could collide if your numbers are off.

As Tim pointed out, with new pistons you would prefer to go oversize and then match bore the liners to the pistons. I am probably the lone disenter here, but IMHO the liners do not need to be bored in the block. The service manual says specifically to remove them to do that procedure, or prefereably purchase new ones. Ferrari will sell you brand new ones already to run, honed and ground to match thier pistons, and thiers wernt bored in your block. The early 308s have cast steel liners, very hard stuff, long wearing, but with new pistons you really want to bore oversize. And while the liners are out you can put new o-ring seals on them.

 

Paul,

Ideally I would agree with you if time and $ were not an issue.

I have spoken to a number of people on this, as I have to take out my engine to repair a cam drive gear that was damaged as a result of a new Ferrari lock nut coming loose (and yes it was torqued properly) and I intend to upgrade to high compression pistons while the engine is out.( in for a penny ... etc)

Mike Elliot (30+ years of rebuild on 308's and 246 engines) of Superformance in the UK indicated that they never take the liners out unless they are really bad. They always bore the liners out to oversize or 82 mm in situe with a plate that holds the liners torqued in position.

They always recommed moving away from Borgo pistons(as have others I have spoken to), apparently by comparison with what is now available from JE etc, Borgo are like a heavy old Dinasour. (There is no price differential original Borgos and replacements are approx the same $)

I personally know 4 guys that have had Superformance do this without issue. If Mike/ Ron have been doing this for 30 years and never had a problem I am inclined to believe them.

Grant I would suggest that you send Superformance an email or call them and speak to Ron (Mike is now retired) and get his advice first hand. The guys are very helpful and then make up your mind as to how you want to proceed.

Tom

 

From my experience you rarely need to go to 82mm unless you have to have the extra displacement. Changing from an 81 to 82mm overbore in near .040" and will be the last time you will ever be able to bore those liners. Most iron 308 liners will clean up at around .010" and almost for sure at .020", at that overbore you still have material for future rebuilds without replacing the liners. To need .040" to clean up indicated a mechanical problem and not just worn liners. As for ordering custom pistons we like the JE's, but they and Wisco and most everyone else are using the same 2618 alloy in their blanks, SRP and some other makers use 4032 which is a higher silicone content and needs a greatly different clearance. The different fit from one 2618 piston to the next is largely due to tapper and cam in the finished bullet but you can specify this as well as listen to the recommendation of the supplier. One of the most important items when choosing and overbore dimension is the ring package, you don't have an endless selection of ring sizes and it is bumper to bore a set of liners and find out you have to file fit a .010" over ring set because you bored to a dimension with no ring availability. What I usually do is figure out minimum required overbore - should not be hard to do but if someone tells me a liner needs .040" to clean up and it doesn't have a broken ring or a zillion miles I would be suspect. Once you know that you can find a ring package that fits your bore dimension and the size and material needed for your build. Then you can get the pistons ordered and have the liners finished to match once you have the bullets.

That is what I usually consider when doing this, the other post are excellent advice and your piston maker will have other suggestions as well. It is not difficult to do just follow the carpenters rule of thumb and 'measure twice, cut once'.

 

I agree that probably 0.010" is all you need to go.

I would be careful about changing the compression ratio much on a street car. There are other variables that will be affected.

You will want to consider the choice of fuels that may be available in the future.

 

Grant,

Who is doing the work?

Stock CR is 8.8:1 just the same as stock HP is 255 I'd hang around 9.5:1 and no more. Despite all the folks who will say go higher, none of these folks really know what the gunk that comes out of Kurnell is really like. If you need to be convinced of this, ask Carl Jones how his 308 is after a bad batch of Mobil purchased on the Hume Highway back while I still lived in Sydney!

 

Grant, if the machine shop has not worked on a Ferrari V8 before, don't let them learn on yours. Can you share the name of the mechanic and machine shop? I know most of them in Sydney - good and bad - who profess to know something about Ferraris (not that I do).

Just a word of caution here: 308 short blocks are tough - REAL tough. Something has to have "happened" to warrant a rebuild. I'd be more concerned about working out why it needs this rebuild. Unless some core issue is addressed, then you'll be doing this all over again in a few years.

Dave

 

I believe the Euro cars were 9.2:1 with BHP~255. The US cars were 8.8:1.

 

I have really been working hard to be less sarcastic, so maybe it didn't come through in my post (all that work is paying off!), so let me rephrase

CR is 8.1:1, just like HP is 255, just like the tooth fairy is dating the easter bunny.

Sorry

 

sound like you guys you no your stuff.......Q...i have been told that 308 and alfa/rom cranks are bullet proof and hardly wear thus never needing to be reground... unless there is scoring on the journalls etc!! how true is this ........... cheers rizzo

 

Grant, PM sent

 

I would be measuring that cylinder/piston/rings very carefully vs. the other 7. Your motor may have had a "one cyl. repair" sometime in it's past.

 

Good advice.

Don't assume anything, now is the time to be thorough.

 

I've done quite of bit of R&D on these blocks, sleeving, etc. for Nick as some of you know. The stock Ferrari liners are finish honed then installed into the block. This is not the preferred method by any means since the liners will never be round once the heads are torqued in place. That's why Ferrari used a four ring piston to control oil usage and blow by. The preferred method would be to bore and hone the liners in place using torque plates with nuts torqued to spec along with the head gaskets that will be installed upon assembly. You may indeed need to purchase an extra pair of head gaskets to do this.

Rings are going to be more easily found in .020" over than .010" over. It will also be much better to bore, leave .005" for honing and hone .020" than to try and hone these blocks .010" without boring (see below). I like the Total Seal Xtreme conventional gap style ring sets in these engines. A 1.2 1.2 2.8mm ring package for Honda 1.8 liter 4 cyl works well and will reduce friction considerably. The bores must be finished as above. J&E makes nice pistons for the Ferrari (all I use here for street race or race only applications) but you need to realize the 2618 alloy they use will require more piston to wall clearance and will most likely make a bit of noise when first started. You can look into Ross pistons which can be set to run considerably tighter for a street only engine.

It is difficult to hone the stock sleeves in the block. Another reason why Ferrari finished the sleeves before installation. There is very little over stroke between the bottom of the stock liner and the main bearing web. You must find a shop equipped with shortened stones and experience to get the bottom of the liner to size without taper or out of round. You should be able to find a properly equipped race shop in your area that can handle this for you. They may have to make a pair of honing plates as well. I made a custom set myself.

Compression ratio is dependent on the quality of fuel you have in your area, your tuning abilities, etc. With EFI and knock sensors, the compression ratio can go to 11:1 with 93 octane gas. Otherwise I would keep it to 10:1 with EFI wiith out knock sensors or with a carb engine. There is no reason to run any lower compression ratio unless you plan on running 87 octane gas.

Steve

 

Whatever happened to the fabled "4 liter engine"?

 

This is the last pic anyone has seen of it that I know of. Notice the material at the bottom of the block where the liner locating bores meet, as well as the metal around the head studs. I know they meant well, but compared to a stock 308 engine thats a lot of missing material in some very heavy stress areas. For comparison, a stock engine is over a 1/4 inch thick down there between the locating bores, and the head bolt studs are nearly that far from the outside edge of the liners. Not to mention the liners would be so flat sided against each other no coolant would get past them. $20K is a lot of money to spend to have this done to your engine and go experiment with it. I think a Blower or the V-12 conversion makes a lot more sense before going this route.

To be really honest though this thing might actually work, but it would need some long term serious track and dyno time to really be convincing. I think it would be a short test.
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Money or lack of has stalled the completion of the 4 liter. Nick is supplying Mark Lewis with a pair of 4V heads shortly which I will modify for the 4 Liter. The rest is pretty much up to Mark Lewis as far as completion goes.

Nick has ordered a 360 crank and rods for me to work with to build a larger version of the 3.5 liter. If I can make those pieces work in the 308 328 blocks, we will have a cost effective solution for an engine larger than 3.5 liters.

I attached a photo showing Nick's 3.5 liter finish machined block with sleeves being installed. This block is in the 2V 3.5 liter street engine (Nick's personal car) which made 340 hp on Carobu's dyno.

Complete 3.5 liter engines are available to order now through Nick.

The blocks and other pieces are available separately for those of you wanting to do your own work. The sleeves are machined from high strength Darton ductile iron blanks. Sleeving of your block runs right around $5K through Nick.

Steve
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