Coilover suspension upgrade (BiTurbo)

alpa

Member
Messages
169
My turn.

I installed the coil-overs on my freshly rebuilt 222E (2.8 18v). I needed to re-adjust them twice to find the good balance, the ride is comfortable. So far I did not push the car too much because I'm still breaking in the engine (250km), so I can't judge how the rear is good. But it's definitely not worse than what I had before. The front is sharper than before.

It's easy to install, well made, strong.
The main advantage is the freedom to adjust all the parameters.

The main problem is the maximal front ride: it's too low. It's about both springs and the strut length, the overall range. This is the problem if you want to have an every day car, not just a show off toy driven 500km/year on flat streets on sunny days. Worse if you want to be 4 persons in the car.

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Explanations.

The 200 front is low. I managed to have 9.5cm of clearance between the engine frame and the ground. It's not a lot. 400 versions are 2cm higher. I've never understood where is the difference between the versions. On modern routes made for suv and 4wd trucks/tractors you need more. Not to mention some underground park places. The stock exhaust was too low on speed bumps, so I modified (welded) the front part of the exhaust to have it 1cm higher, at 1cm from the body (like what was made on Ghibli and Qp4).
The problem area is near the gearbox, this is where the exhaust is usually smashed.

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On the rear it's all fine, you can adjust as low or high as you want (until the wheel camber gets too high/low). The rear of 200 versions is too light and there is no anti-roll bar, so I want it to be as low as possible (to minimize the body roll). For the same reasons you can't make it too stiff, it won't stay on an average route with bumps.
400 and ghibli have heavier rears, they won't be as problematic to adjust.

My shock adjustment is 12 clicks on front and rear, instead of suggested 15 front and 14 rear. However I rebuilt and modified the front of the body around the engine (it was all rusted and smashed) and the engine frame, so it's much stronger than before. I guess with a stock car it may feel differently.
So far I kept the default caster which is like stock.

One of the huge benefits is to be able to balance both sides of the car. Mine has had at least two accidents and was repaired in the usual way: as they could with a big hammer and torch. So the car is not symetrical. Really not. But none of these cars was straight even brand new. So being able to make it parallel to the ground, with the same dynamics on both sides, is appreciated.
An advise: don't make the front too stiff if your car is stock. The front of all versions, except for qp4 (that was made of a better steal and was slightly redesigned by FIAT), is weak. The weakness is around the strut "towers" (the body bends) and exactly where is the rear of the engine frame (the body cracks in this area).
 
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Messages
198
Very happy to hear you're pleased, i'll "dump" some specific data points here for Quattroporte 4 and the other models,
Over the production runs shipping method has changed to aid install especially earlier the manual caused confusion in front ride height we noticed

As the system is shipped lose the intended front preload on the spring must be setup by adding it in after or prior to install, this will give correction compression
We have noticed that the reaction differs quite a bit by cars as they get heavier and longer, for example what may be a thigh setup on a 18v spider, would be soft on a Ghibli with a 6 speed

Also a very important effect which may at first seem illogical is that as the car is brought to level which in-front puts preload on the springs so that spring curve is where we want it, damping click must go up in a range around this.
So damping made harder can make the car feel smoother, better managed/less harsh off-course that effect is finite eventually compression will firm it up.
It's not only on BiTurbo that we encounter this effect when we install the Quattroprote V systems the same happens, damping too soft makes them "harsher/bouncer" customers experience more comfort with more compression.
That said QPV has a very large difference in feel between a DuoSelect and ZF with the same shocks.

This also where a range differentiation in springs is where we've got a adjustment range for V6 and V8 cars
For example what we've installed here in the shop on Quattroporte V8 is a setup using the V6 springs with quite some preload and moving the damping curve upward to get comfort to pre-evo setting 3 on the KONI suspesion.
That specific setup doesn't translate to for example a 2.0 V6 Quattroporte which is much lighter but has the same chassis (weight balance moving backward)

Same can be said for Shamal which is super short wheelbase but front end heavy (but not nearly as much as QP IV V8) it will require quite some extra preload compared to a similar ride on a Ghibli.
And the damping setting needs to come up so both load's are in there tuning range. (you can't run the dampers for example in 10 with a lot of preload)

For example damping testing on the most extreme application Quattroporte IV V8 that is setup to retain comfort: (Benchmark is Koni setting 3, which is some where between normal and sport on EVO)

Rear
  • 20 > comfortable, under-steer tendency
  • 24-27 > sport, neutral steering good, great torque/accelerating control (throttle out of corner)
  • 29-30 > hard, I'd not run so high personally makes it very snappy
Front
  • 24 > soft, watch out with large wheels/tire sizes (for example max cornering speed roundabout, bumps whilst cornering) FYI test car was on Ghibli GT wheels, the pre-evo wheels would make that totally different.
  • 26-27 > sporty nice balance if rear is at 25 (front to rear balance heavily effects the long wheelbase)
  • 29-30 > very sporty could be experienced as hard by some customers, others are fine with it

Other setup note specific to QP4 is due to the added wheel base and the front weight of the V8: (to-date we've kept the QP's soft with good damping as they're cruisers)
  • Rear shocks carry much less weight so shock compression is the main tuning tool,
  • Front suspension on soft V6 springs allows for comfort and having the compression of the damper control curves and undulations, harder springs would make it more like a coupe but lose compliance as cruiser
 
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alpa

Member
Messages
169
My 430 and QP4 Otto have had adjustable Koni shocks and I've always been driving in 2nd position. On the 430 I've got 2 Koni ecus: one for the front, one for the rear. And still, always end-up setting at 2 both. sometimes the 1st on the rear when it rains. To me this Koni system is a toy: yes I feel the difference, but it's useless.
These adjustable coil-overs are a real thing. You can adjust for the ride you like.
I don't drive modern cars, however I don't believe in all these "street/sport" settings on 20" touch screens. Yes, on Panamera different suspension settings do really make difference. And the car will stand (and will be very performant) on the track. But it's Panamera. Most of the cars will be performant in just one pre-defined "mode". It's the same with biturbos: they will be optimal in one mode, and good/average in some others. So I'm quite sure one optimal setup is enough for 99% of situations. The day you want to go to the track with your QP4 or Ghibli I'd suggest to worry about things like engine lubrication and cooling, body strength, braking power. The suspension adjustment will be a minor problem.

I bought these coil-overs for my 3 biturbo :).
 

Motorsport3

Member
Messages
869
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A bit off topic but have you fabricated this to protect the cats ?

Do you have an issue with trapping small stones?

I found that the exhaust system and the cats are hanging too low in my QP4, and particularly when it's full it's quite easy to scrape if you go off tarmac, so on the look out for a solution...
 

alpa

Member
Messages
169
I made all that myself. I added generic cat converters and assembled like that. So that they fit the shaft tunnel.

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The plate is a protection when cats scratch the ground, it's a 1.5mm SS plate. Otherwise they are smashed. Small stones aren't an issue, asphalt is.
As I explained previously I tried to place the exhaust as high as possible. I had less problems with my 430.
To solve these issues you can buy coilovers . And you'll also solve problems with the sloppy qp4 suspension.

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F456M

Member
Messages
124
I made all that myself. I added generic cat converters and assembled like that. So that they fit the shaft tunnel.

View attachment 111832

The plate is a protection when cats scratch the ground, it's a 1.5mm SS plate. Otherwise they are smashed. Small stones aren't an issue, asphalt is.
As I explained previously I tried to place the exhaust as high as possible. I had less problems with my 430.
To solve these issues you can buy coilovers . And you'll also solve problems with the sloppy qp4 suspension.

View attachment 111833
Cool project and well done. Why are the exhaust not crossed? I had the original Y-pipe to the single-catalyzer on my 1991 222 4v. This was too low and I broke it completely when I hit a rock when reversing on an un-even road. My catalyzer was melted and made a big restirction. Instead of replacing the parts, we put two separate pipes from the turboa to each rear muffler. After this modification, the engine seemed to develop much less throttle response and less power at low revs. Later I sold the car. Same with my Ferrari 456M. Went to separate pipes, and the car was less powerful at low revs, and higher consumption. Both the 456M and my present 550 has a x inside the OEM center muffler. People say that a V12 don't need an X-pipe opposed to a V8. The Quattroporte 1 had separate piping for each bank. On the Indy (and probably more models) the exhaust goes into one pipe and then exits out the back in two pipes. These have better sound and probably more power. The first Biturbos had separate piping, left side 1 meter longer than the other, but they still went together inside a single rear muffler. Later when the Biturbos got two separate rear mufflers, the extra meter length disappeared and when the Ghibli with static ignition came, the exhaust went to separate again (as far as I now). What is your opinion? I would get the old Biturbo style exhaust as this had the best sound picture.
 

alpa

Member
Messages
169
Cool project and well done. Why are the exhaust not crossed? I had the original Y-pipe to the single-catalyzer on my 1991 222 4v. This was too low and I broke it completely when I hit a rock when reversing on an un-even road. My catalyzer was melted and made a big restirction. Instead of replacing the parts, we put two separate pipes from the turboa to each rear muffler. After this modification, the engine seemed to develop much less throttle response and less power at low revs. Later I sold the car. Same with my Ferrari 456M. Went to separate pipes, and the car was less powerful at low revs, and higher consumption. Both the 456M and my present 550 has a x inside the OEM center muffler. People say that a V12 don't need an X-pipe opposed to a V8. The Quattroporte 1 had separate piping for each bank. On the Indy (and probably more models) the exhaust goes into one pipe and then exits out the back in two pipes. These have better sound and probably more power. The first Biturbos had separate piping, left side 1 meter longer than the other, but they still went together inside a single rear muffler. Later when the Biturbos got two separate rear mufflers, the extra meter length disappeared and when the Ghibli with static ignition came, the exhaust went to separate again (as far as I now). What is your opinion? I would get the old Biturbo style exhaust as this had the best sound picture.
I don't think X-pipes on V6, especially on an odd-firing turbo ones, is of any performance interest. They obviously work on NA v8 because of the pipes length and engine cycle frequencies.
There was a cross pipe on Ghibli and QP4 but I think it's more to equalize O2 levels, even though this does not really make sense with two lambda sensors. Maserati choose so many nonsense solutions on injected biturbo ...
All distributor injected biturbo with cat converters had one cat, simply because there was just one lambda sensor. Forgive me but I don't think replacing one cat conv with a dual exhaust line could worsen the engine's response and power. This could be true on NA engines (people talk about a restriction that improves torque, well it's not exactly that but it's a consequence of scavenging processes) but I doubt this could be true on a turbo engine. Don't believe your feelings, only measures are real.
May be unrestricting the engine made it run leaner. Biturbo are poorly mapped and run quite lean.
All 2.8 and 24v engines had dual pipes and as we know they worked quite well. The 222E is still running 0.4 bars boost (still breaking in, 600km) but it's really fast and responsive.
In my case I actually have an issue: I'm running the stock (retuned) injection with one lambda channel but two separate cats. As I have a dual channel wide lambda (Zeitronix ZT-4, don't use the Innovate ****), and there is a richness difference between engine banks, I plugged the lean bank to the ECU. So that none of cats is too lean. I'm going to increase the rich/lean cycling amplitude of the ECU so that both cats cycle in their rich/lean zones. So far I did not measure any excessive heat in the reach bank cat.
I'll also make modify cam pulleys to make them adjustable. As heads were skimmed by 0.5mm (oxidation) both banks are not timed the same.

Clogged cat: I suspect these old cat converters were not strong. May be they were not heating enough, may be they were overheating. I've got 3 such cat converters and all were dead clogged or cracked inside.
The old biturbo and 2.0 18v uneven pipes are for the sound, so it's a matter of preferences. May be there was a requirement from USA regulations, as the carb biT were sold in the US. But as far as I know 2.8 versions sold in the US (there were few 2.8 Spyder and 430 items sold there) were stock like in Europe, with two exhausts behind the cat.

If you want a dual line with the stock cat management then you should make a cross pipe and install the lambda sensor in this pipe. But you must be carefull to make the sensor be well exposed to both lines (so a kind of X-pipe is better). Or you just unplug the lambda and run open loop.
 
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dt95aac

Member
Messages
116
I don't think X-pipes on V6, especially on an odd-firing turbo ones, is of any performance interest. They obviously work on NA v8 because of the pipes length and engine cycle frequencies.
There was a cross pipe on Ghibli and QP4 but I think it's more to equalize O2 levels, even though this does not really make sense with two lambda sensors. Maserati choose so many nonsense solutions on injected biturbo ...
All distributor injected biturbo with cat converters had one cat, simply because there was just one lambda sensor. Forgive me but I don't think replacing one cat conv with a dual exhaust line could worsen the engine's response and power. This could be true on NA engines (people talk about a restriction that improves torque, well it's not exactly that but it's a consequence of scavenging processes) but I doubt this could be true on a turbo engine. Don't believe your feelings, only measures are real.
May be unrestricting the engine made it run leaner. Biturbo are poorly mapped and run quite lean.
All 2.8 and 24v engines had dual pipes and as we know they worked quite well. The 222E is still running 0.4 bars boost (still breaking in, 600km) but it's really fast and responsive.
In my case I actually have an issue: I'm running the stock (retuned) injection with one lambda channel but two separate cats. As I have a dual channel wide lambda (Zeitronix ZT-4, don't use the Innovate ****), and there is a richness difference between engine banks, I plugged the lean bank to the ECU. So that none of cats is too lean. I'm going to increase the rich/lean cycling amplitude of the ECU so that both cats cycle in their rich/lean zones. So far I did not measure any excessive heat in the reach bank cat.
I'll also make modify cam pulleys to make them adjustable. As heads were skimmed by 0.5mm (oxidation) both banks are not timed the same.

Clogged cat: I suspect these old cat converters were not strong. May be they were not heating enough, may be they were overheating. I've got 3 such cat converters and all were dead clogged or cracked inside.
The old biturbo and 2.0 18v uneven pipes are for the sound, so it's a matter of preferences. May be there was a requirement from USA regulations, as the carb biT were sold in the US. But as far as I know 2.8 versions sold in the US (there were few 2.8 Spyder and 430 items sold there) were stock like in Europe, with two exhausts behind the cat.

If you want a dual line with the stock cat management then you should make a cross pipe and install the lambda sensor in this pipe. But you must be carefull to make the sensor be well exposed to both lines (so a kind of X-pipe is better). Or you just unplug the lambda and run open loop.
I have to agree with these findings.
I also run a custom non x-piped stainless steel system on my 2.0 Ghibli, which I initially had made in order to be able to measure emissions from each cylinder bank separately.
I found the engine to be a lot more free revving especially in low to mid rpm and decided to keep it without the x-pipe.
 

alpa

Member
Messages
169
I stop answering here to exhaust related questions to not hijack the ASM's thread about coilovers. Please start a new discussion.
 

alpa

Member
Messages
169
...
Also a very important effect which may at first seem illogical is that as the car is brought to level which in-front puts preload on the springs so that spring curve is where we want it, damping click must go up in a range around this.
So damping made harder can make the car feel smoother, better managed/less harsh off-course that effect is finite eventually compression will firm it up.
It's not only on BiTurbo that we encounter this effect when we install the Quattroprote V systems the same happens, damping too soft makes them "harsher/bouncer" customers experience more comfort with more compression.
...
Could you elaborate on that ?
It's not only illogical, it's against what teach the books about suspensions.
Or are you simply saying that with firmer springs more dampering is needed ? Yes, dampering must be "critical", or is this called "optimal response time" for closed loop systems ?
 

alpa

Member
Messages
169
An update
I understand these coilovers come with the 62.205.006 springs on front. As I previously explained it's too low for an everyday usage.
I installed 62.220.005 springs on front of my 222E. This allows an a slightly higher clearance and the ride is smoother. Under a heavy braking both spring types will stop the car at the same clearance. Note that I modified the engine subframe and body on the front so the body is much more rigid than stock. With the sloppy stock body + rust the effect could be less noticeable.