Any performance mods for 456?

Hi Ed
Terry will chip in here,
The 456 is in a higher state of tune than the 550 but from what I understand it has restricted breathing.
There are EPROM chips available and there is thread with a remapped car at 500HP.

From Dave456's experience just making sure the throttle bodies are correctly balanced physically and electrical makes a noticeable difference.

 

Eddy,
A fast and economical way of increasing the 456 engine's power is resonator delete...i.e.,
replaciing the center exhaust resonator with straight pipes. See Bradan...they have pipes all ready to install. Remove bolts and resonator and replace with Bradan's straight pipes.

Hope this helps.

 

Have you tested your car on a dyno to measure what you are getting now?

 

Also instead of the 35lb rear cans get a set of tubi straight pipes. No its not too loud. Neither my wife or neighbors object. On the other end BMC free flowing air filters or K&N if you can find them. Definitely made a difference on my 575. Wish I had done a dyno before and after. Bradan says their straights are worth 18-20. Filters worth 5-7. Tubi no restriction straights? Gts Bruce

 

Is your plan to rebuild a wrecked 456 or would you want to fabricate a replica of another model that you would use the 456 engine in?

 

Ed, it sounds like you're building a "kit car" or you're doing an engine swap with this 456 engine? Do you know whether you have the engine from the earlier 456 GT car or the later 456M GT? It's important to know, as the two engines have different firing orders.

If the covers for the fuel rails are still on the engine, they'll be marked with either "456" or "456M". Otherwise, if you have the VIN of the car it came out of, that can be decoded and will provide this information

Once you know which engine you have, you should go to ferraridatabase.com and download a Workshop Manual for the 456/456M, and that will help bring you up to speed on the engine basics and troubleshooting.

Will you be trying to reuse the stock engine management system, or will you be changing to aftermarket ECU's? The earlier 456 GT's had Bosch Motronic v2.7 ECU's, which were non-OBD2, while the later "M" engines had v5.2 ECU's which were OBD2. The earlier ones are easier to hack & tune, and there are several tuners that can remap them, while the later 5.2 ECU's have proven difficult to hack, and AFAIK, only one tuning shop in the UK has been successful remapping them.

Referring to your initial post/question about power adders, the engine probably isn't a good candidate for forced induction, since its stock compression is already 10.6 to 1, so unless you plan on lowering the compression a bit, force feeding it could become tricky, and VERY expensive if you don't get it right. Having said this, there is a Japanese tuner, Saurus Garage, who twin turboed a 550's engine years ago, however they "built" that engine for forced induction.

Assuming you'll stay naturally aspirated, and depending on whether you need to retain the stock engine management system, or pass an OBD2 or emissions scan will determine how much "hotrodding" you can do with this engine. Obviously, reducing the restrictions on both the intake & exhaust will allow it to breathe better, and will produce higher top end HP figures. This is an interference design engine, so you'll need to be particularly careful with the camshafts and changing their lift/duration.

Can you tell us more about your project and your intended use for this engine?

 

The 5.2 Motronic was introduced in the 456GT, I believe in 96 - you can also tell if the car of the alarm key fob or not.

 

Kudos to you for doing it; why don't you start a build thread? How authentic are you going to try to make it? It would look really yummy with some ITB's, mounted either direct to head, or with the existing intake in a crossram fashion. (FWIW, I'll be using a cut up 456 intake manifold with some Jenvey's for my 550 build.)

 

Ed- Not controversial to me
I agree with John. I'd love to see a build thread on your project...

 

I do he got a quote for replacing the valve guides.....

 

Yup. Cheaper to drop in a Corvette LT1.

 

Ed, it's probably on the order of $8-10K if you pay someone to do it all, with the engine in the car. I think that's about what Allan has in his, but I believe that was with all new valves, too.

In your case, I think it could be done for less than half that if you can do most of the grunt work yourself, and just bring the heads to a specialist for refreshing. Do be very careful who you let work on these heads, however......

Worn guides in an assembled engine are tough to detect unless they're extremely worn and then they show up during the compression and leakdown tests, because the valves are no longer seating properly. Excessive oil consumption is often a tipoff, as is oil smoke, but both those symptoms can also indicate other issues. Heavy oil fouling of the intake valves' bowls is another visual indication that you can check when you pull your intake manifold.

The best diagnostic is to check the "slop" or side to side movement of the tops of the valve stems after the retainers & springs have been removed. If you can "feel" any side to side movement, your guides are probably worn. Machinists have precision miniature dial bore gauges that can check the ID's of the guides and compare that to the OD's of the stems to get a quantitative measure of their wear, but most of us don't have access to these tools, so we use the "slop" technique as an indication

Ferrari had valve guide issues with many of their engines built in the 90's. They used bronze guides for good heat transfer, but some were too soft and wore prematurely. In the later cars, such as the 575M they switched to a sintered steel guide, which solved the wear issue. Since you have a late model 456 engine, it would be interesting to know which type of guide you have. The bronze guides are yellow with a reddish tint, and are non-magnetic, while the steel guides are silver and are magnetic.

Prior to pulling the engine apart, be sure and do the usual diagnostics, ie compression & leakdown tests and have a close look at the plugs. If/when you pull the heads for reconditioning, take the opportunity to leakdown the cylinders to see how your rings are sealing. You surely don't want to do an expensive top end rebuild, reassemble the engine, then discover your bottom end still has issues.

 

Sorry to revive an old thread. Is the above statement still correct and who was it that succeeded?

 

Contact Trevor and see what he can do. I imagine he can help both 2.7 and 5.2 456s and 5.2 456Ms, as well as 5.2 550.

Incidentally, no 456Ms were fitted with sintered steel valve guides. They all have bronze.

 

And who is this "Trevor" of whom you speak?

Tubi does not list the straight tailpipes any more the I saw somewhere the Braden solution is also unavailable now.

 

Fabio sells them.

As far as performance I run:
*Fabio’s deletes (I had his H pipe too but the combo sounded bad)
*MSW steering ECU
*BMC filters
*New throttle cables & synced the throttle bodies
*Improved cooling
*Replaced all emissions and vacuum hoses, smoke tested so there are no leaks.

My 2003 GTA is MUCH faster than when I got it. Much quicker AND brakes the tires loose on the 1-2 shift now. My mechanic runs a 2000 GTA and acknowledged mine was way faster. We just think it is the combination of mods and having the most recent major (finally) done correctly.

 

@Mirek I have seen your posts related to the sound of the car in another thread I believe, as well as the picture of inside that central muffler. Do you happen to have soundclips of your experiments? If not do you mind taking a video of how it sounds now with the mufflers delete?
I would tend to think that removing that central muffler would get more gains than the back boxes but both could be minor gains in fact.

 

Another thing I think would work great is to change the final drive ratio. I guess if you were sacrificing top speed to something like 250 kph, much more than enough except if you live in Germany, you would see great increase in performance overall. These days where you have cars like Volvo that are limited to 180 kph, and depending on the legal limit in your country you could even go agressive and use a final drive that maxes out at 200kph. I mean here the maximun you can go is 120 kph, even if you wanted a little bit of a (legally risky) joy ride once in a while 200 to 250kph top speed is enough. Even if you were to track the car it's hard to find tracks with a long enough straight to hit more than 250kph. Maybe some F1 tracks like Shanghai F1 you may reach 280kph at the end of the back straight... So I say for every day street driving a final drive that removes you 15%-25% top speed would work great! And of course keep the original one on a shelf for 300kph bragging rights