348 Engine Upgrade

Some of you might be aware of The Stooge's efforts to pull more performance out of the 348 engine. We have explored a bunch of different ideas, some work, some maybe not so much as well as different paths to take. My personal path has been to explore the maximum performance gains while keeping the car CA smog legal. I kind of deviated from this by installing Fabspeed headers and Gothspeed cats, but technically the car still complies as long as someone doesn't look too hard at the headers. I could easily return to stock if necessary.

Here is a list of everything we have done in this program:
1. Remove MAF screens
2. Bore throttle bodies
3. Add volume to the intake manifold via custom spacers by Gothspeed
4. Porting and polishing the intake plenums and runners
5. Upgraded aftermarket 4-hole injectors from OsideTiger - these have a 20% higher duty cycle than stock
6. Custom X-pipe muffler from Gothspeed
7. Replacement metallic core 200-cell cats by Goth
8. Fabspeed headers
9. Challenge chip set in ECU - yes, there are small, but notable differences in stock chips for the 348

All these were good for a sizeable increase in output and response. We measured an approximate 10% increase in power to the rear wheels before the installation of the headers. Sadly, I missed a dyno session for the post header install before we went to the next level.

Now debuting is the next level. We took a replacement set of heads and upgraded them with larger valves, new seats and guides, and some serious port tuning. The engine is going back into the car this week as part of its major and we will dial it in before another dyno test and report back. Stay tuned. Our goal is to exceed a 100HP/liter output and knock on the door of 355 performance.

It is possible we will need to upgrade injectors and possibly the engine management system, either completely or piggy backed, but one step at a time. We need to make sure that our air/fuel is within a safe range at max rpm and wide-open throttle. I am concerned most about running lean, although I think we are okay. Exciting stuff.

 

Sounds awesome Vince

 

Great stuff!!
I think the standard injectors are already struggling at 184cc (that what mine flowed when I had them serviced), so I would be replacing those with some modern quad spray over 250cc.
Then you'll need to run a programmable ECU like Motec or Link which is what I am going to do. I think its a waste of time fiddling with the dirty old Motronic, they are archaic pieces of kit, we have much better and easier ways to manage engines...
So in doing that you'll want to raise the RPM limit up to about 8700-8800rmp, and that alone will also gain some power. You'll be able to dial in a better ignition and fuel map, job done...
This is what I plan to do, looking forward to it...

 

Interesting. Due to our smog restraints, one has to be careful about changing too much from stock. My injectors are over cap already - I think they are rated at 220. I have chips with the red line at 8000 I can install later. I wont go too much higher because our timing and stock cams are not ground to give power at much higher revs.

But we'll see. You know it's a slippery slope and I have already invested huge dollars (for me) in this to date. I am probably going to have to settle for where the chips fall. I can probably afford the installation of a piggyback controller, if necessary and then I'm tapped. At some point, spending $15K or more in search of additional power gets undone by the cost/benefit ratio. I probably could have given $20K to Steve Maxwell for a turbo install instead, or maybe sold the car and bought a 360.

 

Only thing I would add is COPs with multi spark. Link ECU.

No need for cams or running over 8k with that timing belt

Any more then that would take away from the cars intention

 

What where the before and after flow numbers on the head work?

 

According to the number on those Bosch injectors, they are indeed 184cc, nowhere near enough for what you want to do, if you have the original 348 injectors in the car.
Thats a shame about modifying in your area/state/country, we are quite lucky here, its not problem for us to do that sort of thing. I think that will be a slightly limiting factor for you.
We have 98oct fuel here and I'll be running mine on that and tuning it specifically to do so.

There will be gains to be had with some more RPM, the F119 will flow more, but how much we don't know, I intend to do some dyno runs to find out and see where the power drops off and go from there, absolutely no point in revving the crap out of it for no reason. This is where being able to modify the fuel map (and in much higher resolution than the old Motronic) will pay off, if it will take more fuel and more timing, and produce more power, then I'm in!!

Indeed it can be a bottomless money pit, how far do you go before the diminishing returns are just not worth it.....that's the big question right?

I feel the engine can be improved somewhat with a decent ECU, not cats, EGR system removed, free flow exhaust, modified intake, no MAF. It will be interesting to see how much more it wants to rev...

All food for thought.....

 

I remember Andy (picture below) did the 355 5.2 intake and ported the throttle bodies and did big injectors etc. I almost bought it but shied away from it due to the modifications, in OEM form it works well.

Few guys did the 355 intake runners as well, some threads are out there.

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https://www.ferrarichat.com/forum/threads/348-throttle-body-porting.346701/
https://www.ferrarichat.com/forum/threads/355-throttle-bodies-on-348-project.125988/

 

There's a guy in our Ferrari club who has done this, looks great.
Not sure if it would actually add power, but certainly makes the oil changes easier, no big air box on top of the oil filter.

 

The 360 air box fits in magnificently also and flos like no tomorrow
Add ITBs with that and your runing

 

Good to know!!
I would love to individual throttle bodies..........................damn, here we go......down the rabbit hole!!

 

Few have done it, you will need adapter plates to bolt the ITB. I got a guy with the drawing who can make them then different ECU and you will need clearance in the rear lid for the ITBs to stick in the air LOL
I have all the parts just need top put it together. Hopefully real soon
Super Stooge Vince got my blood flowing now with his upgrade

 

RPMs in a 348 are somewhat limited by the weight of the valve train. The cam followers and shims are quite a bit heavier than that in the later engines. Limited how much I don't know, but I'm sure the factory considered that when it went to the smaller, lighter lifters and valves in the 355-.
Speedmade on fchat did some great work on doing a shim-under conversion using motorcycle parts. DeeGee's Simpson motor has that setup, though I'm not sure it was arrived at using the same parts. The Simpson motor has some radical cams that required relieving the heads for the bigger lobes. Also a brace across the tensioners.
I still have the entire throttle body conversion kit in a box under the house awaiting further development using the Haltech for injection management. I guess I've gotten too old to finish it. Ran great using the stock mafs and motronics and the stock 355 airboxes. Had Hilborn make me some stacks for it, welded in a bung for an airflow sensor for the Haltech and kinda stopped there when I had to go back to the stock 348 setup for smog. I really wish somebody would buy the whole setup from me and finish it.
Back to finishing Vince's motor.....