Picture of Jonny's Ghibli found on the web

Seems some more pictures from the Maserati event at the TT Circuit Assen are making their way onto the web. Below is a picture someone took of me driving down the start/finish straight with the ANWB roadside assistance mechanic that changed my hose clamp in the passenger seat!


The car is squatting a far bit more at the rear than I thought it was... it didn't look like it was so much on the video. I noticed that the Shamals on the track were squatting a fair bit too, so I wonder if it's to do with the springs used on these cars or maybe the rear axle set up, which was changed on the post ABS variant Ghiblis?

Replacement front section exhaust

Ok, I'm finally writing up the fitting of the replacement front section exhaust.

To recap, I originally ordered a replacement from Larini, but unfortunately it didn't fit so I sent it back and Larini gave me a full refund... so hats off to them for customer service.

Instead, I ordered the Maserati OEM de-cat front section, made by the factory for cars sold to Saudi Arabia. I'd heard on the Maserati Bi-turbo forum (thoroughly recommended by the way... it's a very active forum) that this OEM part is made from stainless steel, although not particularly well finished. However, it's considerably cheaper than the 3rd party replacements available on the market, so I figured what the hell and ordered one.


As you can see, the design of the OEM replacement is very simple and what I'd expect for a straight through design... just straight piping in place of the cats. Not only is this cheaper to manufacture, but it also helps minimise exhaust back pressure, since every bend results in a pressure drop. Also, the OEM replacement is made from a larger diameter tubing... it appears to be 50 mm in diameter versus about 40 mm for the original tubing and the rear section that I have fitted. Again, this is good for minimising back pressure.

Finishing of the OEM replacement indeed isn't great. Where this is particularly noticeable is in the fitting of the small diameter cross flow pipes that joint the left and right side pipes to maintain equal (positive) pressure on both sides.


The picture above shows the inside of the piping and you can see on the left hand pipe there's a considerable sized "burr" sticking out into the inside of the pipe. Essentially, the factory never took the time to clean up after welding in the small pipe. It's not a major thing though.

So, everything was looking OK until the replacement section was positioned against a similar part to that which it was replacing... it was about 7 cm longer! It turns out that when the ABS variant of the Ghibli was introduced in 1994, Maserati decided to lengthen this front section exhaust. This is reflected in the part numbers, where the part numbers for this section subtly change. But the strange thing is, the rear sections didn't seem to change, so I can only assume that the rear section remains the same length for all variants of Ghibli. Therefore, the additional length of the front section must be taken up in the bends of the rear section on the post ABS variant cars.

This explains quite a few things, in particular why the Larini part didn't fit. It now seems obvious that there part had been modelled on a post ABS variant Ghibli and therefore should fit these cars no problem at all.

However, this realisation didn't help me!


Fortunately, Jorrit at Auto Forza who was fitting the exhaust for me discovered that there's a steel workshop not far from his workshop that specialises in forming stainless steel, particularly stainless steel tubing... a lucky break! What they did to shorten the exhaust was to cut it and then enlarge one end of the cut with a mandrel which fits inside the pipe and expands it from the inside. Sufficient length of pipe was expanded such that the other cut end could be inserted inside the expanded end, such that they overlapped by the required shortening length. You can make this out in the picture above.

The nice thing about this technique is that it keeps the inside of the pipe flush and smooth, since the weld of the pipes is made against the outside of internal pipe, which is good for gas flow.


The next problem was that this exhaust replacement was meant for a post ABS variant Ghibli and therefore came equipped with two lambda ports, one on each pipe. However, my car is equipped with a single lambda probe and on the original exhaust this is mounted on the front cross flow pipe in front of the cats, as you can see in the picture below.


I could just have installed the probe on one side with the assumption that both banks run about the the same, but I had another driver, since I'm looking to install a wideband lambda so I therefore want to measure average values from both banks.


The solution to this was to drill a hole in the cross flow pipe and weld in a nut with the appropriate thread for the new sensor. This turned out to be easier said than done, since we didn't have the right sized nut to had to make one, plus the diameter of the cross flow pipe is quite small, so the face that was being welded onto it had to be profiled.


However, the end result turned out fine. We made sure that there was sufficient space to install the probe (get at it with a spanner). It looks like it sticks up a lot in the picture above, but it fits under the car fine without touching the underside, as you can see in the picture below.


Next, I wanted to install an Exhaust Gas Temperature sensor onto the replacement exhaust. This needs to be placed as close as possible to the outlet of the turbo. Unfortunately, I only have one sensor, but it turns out that installing one on the drivers side pipe would be tricky since there's not much space. So we decided to install it on the passenger side.


As you can see from the picture above, we drilled another hole and welded on a nut with the appropriate thread pretty close to the flange connection that joins the exhaust to the turbo outlet manifold. The picture below shows that the location turned out to be spot on, with sufficient space for the sensor and to run the stiff cable into the cabin.


When it came to fitting the replacement section, we realised again that the mounting lugs didn't align with the mounting bracket that is attached to the gearbox housing. The picture below shows the OEM exhaust, but it seems when Maserati changed the design of the front section they also increased the distance between the two pipes around the gearbox. As a result, I've had to order a new mounting bracket to attach the replacement section to the gearbox housing. Fortunately, it's quite cheap!


Once the replacement front section was installed, the rear section needed readjusting to align the outlets in the rear bumper... we ended up having to get the gas out and heat up the rear section to try and get a bit more bend in it (but stainless steel is not as malleable as carbon steel). In the end, a tighter rubber hanger did the trick.

As you can hear on a previous posting, the new front section leads to a much more aggressive rumble from emanating out of the back of the car and slightly louder, although not half as loud as I expected it to be. Performance wise, it's hard to tell if there's any benefit since there's something not right with the engine set up at present... but I'm working on that. Once that's sorted, I may be able to better gauge the value of the replacement.

The new fixing bracket should arrive within the next, along with some wheel spacers that I ordered. I return to Jorrit to get these fitted and while I'm there I'm planning on doing a couple more tests... a cylinder leak test and a change of spark plugs and if we get time I'd like to test the mechanical timing.

Maserati Event at the TT Circuit Assen

On the 8th September there was a Maserati event held at the TT Circuit Assen (Netherlands) organised by the Maserati Club International.

I was fortunate enough to receive an invite in the post a couple of days before the event and prompty re-organised my schedule to attend. I'm glad I did, since there were plenty of classic Maserati cars there to admire and I even got the opportunity to race against a few on the track!

I've posted some pictures from the event which you can view by clicking on the picture below.


I also managed to capture some video footage of the cars out on the track which you can view below.


And my wife captured a bit of footage of my car driving down the start/finish straight which you can see below:


It was great to drive around the tight and twist TT circuit and gave me the opportunity to test out my car on the limit. My first lap was a warm up to get accustomed to the track and I was joined by my wife in the passenger seat. But unfortunately she only lasted one lap before politely asking to be excused since she was feeling a little motion sick... unfortunate because I'd liked her to have taken some in car video footage around the track!

With my wife out of the car, I really got to give it all around the track and found my car handled very neutrally around the bends. As I expected, the car has a high tendancy to understeer on tighter corners, but this is soon compensated with some extra throttle, upon which the car can be made to drift relatively easily and in a very predictable and controlled manner. About one third into the course is a very tight second gear corner where I nearly lost the rear end... but the skid pan training that I had a couple of years ago paid off and I was able to catch it by applying considerable opposite lock. I wish I'd caught some video footage of that!

Twice I blew off the inlet piping connection to the throttle manifold (the one on the left side) which resulted in me having to do a lap with no boost. This made me realise what a huge effect the turbo chargers have on the performance of this car... with no boost I struggled to keep up with an old Citreon that was on the track!

The second time the inlet blew off I asked an ANWB roadside assistance guy for help and he kindly replaced the clamp with a new one. He then timidly asked if he could sit in the passenger seat, so I ended up doing my final three laps with him smiling and giggling alongside me. I don't think he knew what he was getting himself into, but he certainly seemed to enjoy the experience!

I was very impressed with my Mov'it brakes. They performed extremely well with not a hint of fade. I even suspect that I was out breaking the Ghibli Open Cup and Barchetta that were also out on the track; although these cars were undoubtedly quicker on the straights and around the corners, I felt I caught them on braking, although admittedly I was getting a little too confident towards the end and found myself carrying more and more speed into the corners.

I need to do something about my front wheel arches, since around the right hand bends there was a fair amount of fouling occuring, particularly with the additional weight of a passenger. Maybe the wheel spacers I've order will sort this out?

Also, after completing my laps the engine oil pressure gauge dipped low and the warning lamp lit up. I immediately checked for leaks and measured the oil level, but both were fine. I therefore suspect that my oil got a bit too hot, which doesn't surprise me given that my car doesn't have an oil cooler like the later versions.

Driving the car on the track was a great experience and one that I'd love to repeat some time soon. However, it wrecks road tires... my fronts especially over heated and show signs of damage. If I'm to take my car on the track more often then there's a couple of ugrades that I'd invest in... an oil cooler and some stiffer suspension springs would be on the top of that list.

Back at the Dyno

I know I haven't posted anything new on the exhaust yet, or on the Maserati Club International event in Assen, but I'm getting 'round to them.

In the meantime, I've been back to the dyno and to prove it I made a very short video.


The dyno results are below, with the bold lines the new results overlaying the previous results.


As you can see, I've dropped the boost pressure a little which results in a lower peak torque and less agressive ramp up. However, as a result I now have a longer flat section from 4000 rpm to about 5,500 rpm.

Overall performance can be determined by calculating the area beneath the curves... in mathematical terms, if you integrate the curve you'll calculate the actual work done. So although the new curve is not as peaky, across the rev range it's more effective, which should translate as being quicker on the road.

I think there's still some scope to tweak the inlet pressure a little, but it won't yield any big improvements. There's something fundamental preventing me from getting more power out of this engine and I can't quite put my finger on it. Fuelling is not the issue... if anything it's running too rich at the top end, but the chip tuner prefers this since it's much less likely that the engine is going to fail. But it shows that the current injectors are more than up to the job.

So if there's enough fuel, is there enough air? Air supply to the compressors is not the issue, since last time I was at the tuners I did a run with no air filters and there was hardly any difference (so I think the air filters I have fitted are more than good enough). So, maybe I'm getting a significant amount of pressure leak between the compressors and the inlet manifold? To check this I'll need to place a pressure gauge near to the outlet of the compressor and compare this with the pressure at the plenum chamber. It could be that the turbos are having to work very hard to maintain 1.20 bar, which is effecting their efficiency.

Another simple thing to try is to connect the stock boost solenoid... although it won't be controlling the inlet pressure, it's absense may be alerting the ECU and knocking it into safe mode. I don't think the Ghibli ECU has an error check circuit for this like modern cars, but I don't know, so it's worth checking it.

If it's not air supply then it has to come down to timing. I certainly think this is what is preventing me going above 1.20 bar, but I think I should be getting better performance at 1.20 bar, so I'm not going to go down this route yet. I think I should be able to get 360 hp out of this engine at 1.20 bar, so I need to find out what's preventing this before looking at changing out the distribution system.

So... the sooner I install the PLX data logger the better I think.

New exhaust fitted

Well, I got the new mid section fitted on Tuesday. I'll write a longer post over the weekend, but in the meantime, here's a short "before and after" video.

Maserati in the Press

The Maserati brand appears to be drumming up some excitement among the press. I've just been on a business trip overseas and paid my usual visit to the newsagent at the airport to pick up some reading material for the long plane journey. It was a pleasant surprise to find not one, but two car magazines featuring Maserati, both of which mentioning the Maserati Ghibli!

The first I picked up was Classic Car magazine, which had a two page feature on the Ghibli (both the new and the old version!). The second was Car magazine, which had a page rating all the Maserati cars to date as "Good, Bad or Ugly". I'm happy to say that the Ghibli was assessed by both magazines as a great car! Although I'm happy to see that others are starting to appreciate this car, I'm also keen to keep it a secret! However, such good publicity can only be positive with respect to pricing.