Porting and Polishing question.

Krowbar how did you know you had P6 cams? Do you know a VIN where they stopped putting them in the 77 308s?

 

P6 Cams were and after market item, not a factory installed item. The early carb cars have different cams from the later ones (more lift and different timing) but they are not P6 cams.

That being said it's possible a customer asked for the P6 cams in his car new and that's what Krowbar has in his car.

 

There was a Micholetto engine package, as noted for racing applications, Lemans and Group 4, IIRC..

Urban legend, few made, better duplicated with modern technology as described above, I'd think.........

 

Horsepower cost money - how fast do you want to go?
The most important thing about engine modifications is this:

The cost versus the horsepower gained

Do I still have "driveability"?

Is it reliable enough for road trips?

Just look at Ferrari F1 engines, if MS needs more power he dials it in from the wheel and when he needs to "cruise" he dials it back a bit.

WE all do not have the luxury of the special wheel and all th enegineering that goes with it. Ferrari does ont thing that most engine developers do not do, they design the engine to last and give ample horsepower wihle giving long live if you follow the recomended guidlelines.

All said and done, gear changes are cheap way to go fast but lose highway drivability.

Going to high compression pistons puts more load on lower engine parts and if taken too high it just means more broken parts.

Turbos are the least expensive way to improve horsepower without too much internal mods.

Buying racing gasoline to run on street motors is a waste of money if you have not modified the motor to take advantage of the racing blends.

A very cheap way to gain horsepower is to lighten the car anyway you can - fewer pounds to carry means more power is put to the wheels.

Porting the heads without a understanding of air flow, cams, exhaust, intake manifold design is not the way to go. That is why the experts spend hundreds of thousands of dollars TESTING different designs to see what works and countless hours as well.

If you can bolt it on and gain power go for it.

But remember the weakest part is the one you did't check once you had the engine/trans open, CHECK EVERYTHING to make sure. Rebuild it ONCE the right way. that way you will be rewarded with the thrill of Ferrari ownership.

 

On the outer end of my cams, on the shank between the seal and the pulley hub, all four cams are stamped P6 along with the correct part numbers. As I have a US car, I am confident it came with standard cams and pistons, that the P6 cams were installed after at some point.

I also agree with the earlier post, that horsepower costs durability. As the Ferrari is a well designed engine, you get a fairly high level of both. taking out some of the kinks, and restoring the motor to its original euro equivalent, and keeping it tuned should not harm it in the least. The manifold ports dont match, the pistons come up short, and probably very few are ever timed with a degree wheel the way the manual says to do. doing all that it should make its book power of 255 hp. I do not know what P6 cams and 10.4:1 comp will produce. Time will tell.

 

Thanks for this I will check to see what cams I have. If not where can they be purchased? Have you ever had the chance to drive another US car to see how yours compaired with these cams?
I also want to keep mine reliable and durable and will be very interested to see how you get on with these new pistons.

 

Just in the process of a complete rebuild on a 246. JE is doing the 10.6to 1 pistons. They require one of the old pistons and a cast of the combustion chamber with valves installed. I used spray teflon to coat the chamber and common body putty for the filler. Mix it up push it into the chamber and scrape flush with the head. It worked perfectly with no air bubbles. Just lightly tap the back side of the valves and it pops right out.
I also ported and lightly polished all port surfaces and port matched intake and exhaust.
The ring package will include a three piece oil ring set, much better oil control than the original one piece.
Another thing I did was to completely cover, top and bottom of the air plenum and air cleaner housing with a thin self adhesive, aluminum covered insulation. This little car runs so good in cool air that it made good sense to keep it that way all the way from the outside to the carbs,and probably pick up a little h.p. gain along the way. Looks great too! Gary

 

First off i need to explain that my car had two burned pistons when I purchased it, but as I bought it non-running I had no clue as to what I had until I could get it home. I performed a basic 30K service, and ran a leak down test and seen I had major loss from cylinders #7 and #8. All loss was past the piston.

On initial running I found it idled smoothly at 800-1000 revs, and there was not any bad hesitation if the throttle was opened rapidly. On the short drive I made with the car, I found the power to be above what I felt with a 308GTBi a friend of mine owned. Suffice to say burned pistons do not heal themselves and now the entire motor and transmission is spread out through the garage.

After making all my measurements, and cc'ing both the piston dome, and the chamber, I had a actual CR of only 8.4:1. The new pistons will have a real CR of 10.4:1. So I can only assume it will run better, obviously it should idle just as low and much smoother with all 8 working, and should go like the wind. However, as I do want the motor to last, I will run it somewhat rich and probably back off the timing a degree or two from what it can take, and just not push it super hard. It should be plenty fast enough

I do not believe P6 cams are available from Ferrari, but I have seen used ones from time to time but they are quite expensive, from $1000 to $1500 each depending on who has them. There is a cam shop not far from me that I am sure could weld up,regrind and heat treat a stock set of cams into what I have, using mine as a standard. I could look into it if anyone is interested and figure out a cost.

 

In 1994 a friend and I built a carburettor 308 engine to the 1975 308 LM specification for a race car. We ran the engine on the dyno (Engine dyno not a chassis dyno) and it produced 304 BHP at 8,000 rpm. Then we removed the heads and ported an polished them after they had been on the flow bench. The engine then produced 307 BHP at 8,000 RPM and lost power by about 3% everywhere else. Our conclusion was that the heads flowed pretty well stock. I think you'd agree.

I have seen some 308 engines where the inlet manifolds do not match up very well with the heads, so I would imagine that ensuring these were matched (Including the gaskets) would be important. It just so happens that our race engine was well matched to start with so I have no hard data to prove otherwise (As opposed to conjecture and bar room theories that seem to prevail engine building discussions)

Incidentally, if you want to make a street 308 engine that's a European specification in terms of valve lift and ignition timing produce a little more torque and power, make the exhaust valve slightly smaller and bump the compression up to about 10:1. You can experiment a little with jetting as you'll find you have to go to slightly richer mains.

BTW, here is Australia we can get 98 RON pump gas, just curious to know what you can get at the pump in the USA. Unless we can start with the same octane fuel, we have to be very careful about suggesting engine performance mods.

I am currrently building a 10:1 compression 308 engine with stock European specification cams, I'll be sure to report the results of that engine after it's been on the dyno.

 

Sam,

Sorry, I didn't realise you had a 2V injection car. OK, I assume with mods you don't have an issue with emissions but you are in the USA. There are a few nice tweaks you can do to that engine. Firstly replace the two ignition modules with that from a European car, this will give you a more agressive ignition advance curve as well as more overall advance. This could possibly be partly done with repossioning the crank sensor for the ignition but would affect overall advance only, not the curve. You will also need to dump the cats AND the exhaust with the manifolds. The USA manifolds are a horrible pressed steel affair that's a narrower overall diamter than the ROW (Rest of world) cars. Same with the exhaust, go for an ANSA, Tubi, what ever, but that heavy and restrictive standard affair needs to go. Finally, you can install some carburettor camshafts. More lift and more top end.

I have a friend who did this to his car some years back, the power didn't go up that much, up from the stock 214 BHP to 227 BHP but the torque increase was very noticeable, I can't recall the exact figure but it was something like 15% at any speed. The car didn't idle quite as nicely due to the cams I assume but that was the only downside.

 

"I am currrently building a 10:1 compression 308 engine with stock European specification cams, I'll be sure to report the results of that engine after it's been on the dyno." Carl I'm also going to start on a 308 rebuild with JE 10:1 pistons and would like to know more info or any other advice on your rebuild.Thanks

 

Can't add much to what has been said by the board pros before, but just a note from my lowly experience to tag onto what Carl is alluding to. Need to keep in mind what you are trying to do and how you are going to use the car and of course, how much you want to spend. Remember as you really start chasing "horsepower numbers" on the dyno there can be a loss of low end torque or street drivability that is only cured by displacement on a naturally aspirated car. If it's a track car, then not as big a deal. In my project I started getting the 'dyno-syndrome' and started chasing hp numbers at the cost of what I really wanted in street usability. I recovered, dropped back a few top end hp, and am much happier with the daily result.
I think with a 2v FI car, intake and exhaust flow restriction clean up perhaps with a set of cams will give you 260 - 270, or 86-90 hp per liter which is terrific for a 2v street driven car (and similar to a 4-cam 275 street engine). Remember that Ferrari's full race prep'd 2v V-12s were doing about 96 - 100 hp per liter and that was no air filter, wild cams and not much exhaust - and not very street friendly. Certainly compared to a stock Kjet injected car, you'll notice a HUGE difference, and when you go to EFI or Webers, the difference in throttle response will make it seem even much more (as will the sound).
The 4.0 liter conversion as described will not realistically be less than $30K if you just do very simple material/labor calculations (custom crankshaft and Ti conrods fercryinoutloud). Not to mention that the stock transmission gearing will not be good for that engine. That said, there is no substitute for cubic inches (except boost) for sheer umph. The 4.0 will be quite a spectacular piece of work. I think compared to your current 2v injected car, you can be in for $10K or so for carbs, cams and exhaust and single distributor giving 86 - 90hp/liter (as compared to your current 66 hp/liter or so, more with a bit better compression), and have a wolloping fun car that you can take for groceries or the track. And, it will not require any more special maintaining or support bits than a carb'd 308, and is still well within the gearing parameters of the transmission.
Another choice is turbo/super charging, which is the most hp/dollar. It would be a bit easier to do a positive boost car like Mark's and get 350 - 400 hp even at low boost levels, for less than $20K. Just depends on what you want.
I am basically doing a similar normally aspirated project as we are discussing, but to a 3.2 qv (see old threads). Just doing simple carbs and exhaust were about 30 hp gain on the dyno, even with the FI cams. The throttle response (and sound) improvement compared to the Kjet as mentioned before makes it even seem like more. Cams (lift and a little duration) going in this summer perhaps, and am hoping for a streetable 93 - 95+ hp/liter with a solid low end on street gas in a 4v engine that is very simple and reliable.
And MOST importantly in what ever you do, have fun. That's what these cars are all about actually.
best regards, and good luck!
rt