Anyone modifying biturbo v6 engines ?

[henris42]

Well one if the reasons was I had such a pump, and the original was broke.
I have this bigger plan to make it a hybrid, which needs such things. I hope to make a kit of it in near future.

For custom parts, it would be great if we could here have an active list of great (and affordable) suppliers!

 

[alpa]

Hybrid is a fun project. Many issues to solve.
15 years ago I wanted to make a hybrid Mini.
A tip for the throttle: use an old Audi v6 throttle body that has two plates: one small and one large (compatible with the biturbo TB). Block the small plate so that it's always closed. TPSensor will still work. So you'll be able to control and run on the electric motor while the larger throttle is closed.

Custom pistons: CP-Carrillo, Maatz (Austria), Gibtec (US), many others in the US and UK. Most of good custom part companies are in the UK and US. Few in Italy but you'd better speak Italian. Almost nothing in France except for seals, gaskets (but there are companies in every country), and engine bearings: I've got one in France I've ordered from them, let's see how it goes.
For all of them you have to know what you need exactly. Copying existing parts is easier but it's better to improve them especially when they have issues.

 

[henris42]

If you know names in Italy it would be great. I found a nice company there who makes gaskets.

 

[henris42]

Gaskets is Nava Linea Sport http://www.navalineasport.it/

They have a engine seal kit for Biturbo, but its for 18v. Most fits 24v, but not all. Biggest difference was exhaust side gaskets, they are quite bit larger in 2.24v.

Price was however reasonable.

 

[alpa]

Yes Nava is part of Italian companies that work with the ACAR company. I met the owner of ACAR few years ago, he speaks French and English, he knows personally most of famous Italian company owners.

ACAR RAM | Tuning & Race

www.acarmilano.com

Where are listed biturbo gaskets on the Nava site ? I could only find classic Maserati.

There is also CPS for pistons near Milano. However they are only good to copy pistons. Last time I ordered a set of custom pistons they did a crappy work so I lost 800e. They don't speak English, are unable to design anything, they just machine. But they are very cheap: 200e per piston. Regular price is about 300-350e

Beware of the cheap biturbo head gaskets sold everywhere on the web: the black ones with a red sealing.
Below is a comparison of such a cheap gasket that made 20-30k km and less than 10 years, and the true Maserati (gold color) gasket that is from 1989 and made 120k km. The cheap one did not stand and is falling apart. Both come from the same 2.8 18v engine that was on my daily driver, I pulled out the engine a month ago.

I was thinking of ordering a modified version of head gaskets to improve sealing around studs and the oil passage. But I still have 3 sets of 2.8 real gaskets so not sure I'll do this soon. However if someone wants to start this work I would take part of the order. The gaskets are the same for 2.8 and 2.5.

 

[alpa]

UK company where I'm ordering custom made valve guides:

Ultimate Performance – Power by Design

 

[henris42]

Here is Nava tag from the packet:



But as I said before, it was not 100% compatible for 2.24v. Looked like 18v stuff. It was very useful still, I only needed bits and pieces to complete. I did ask Nava about this, I think they'd need a full set of old gaskets that are different to fix.

 

[henris42]

There is also CPS for pistons near Milano. However they are only good to copy pistons. Last time I ordered a set of custom pistons they did a crappy work so I lost 800e. They don't speak English, are unable to design anything, they just machine. But they are very cheap: 200e per piston. Regular price is about 300-350e

Was the workmanship, tolerances and material good? I'm mechanical engineer, and I can definitely design the pistons - just have to find out how to do the rings proper. Never done that before.

 

[henris42]

Also Sergio at https://www.autoepoca.it/ was able to get me new exhaust valve set for moderate price, no idea who was his supplier. Very good quality on tolerances, my head machine shop said no new adjustment cups were needed.

On this I asked the machine shop also if I need hardened valve seats for unleaded/E85. They inspected the heads and said not necessary. Maserati heads have steel rings in the exhaust and any problems are very unlikely enough. They told that only problem in this sense has been Mercedes, which used cast iron ring in some engine. Those actually do break.

 

[alpa]

Was the workmanship, tolerances and material good? I'm mechanical engineer, and I can definitely design the pistons - just have to find out how to do the rings proper. Never done that before.

The pin was offset in the wrong sense, not enough space to fit conrods. Rubish.
Pistons are complex beasts.

Also Sergio at https://www.autoepoca.it/ was able to get me new exhaust valve set for moderate price, no idea who was his supplier. Very good quality on tolerances, my head machine shop said no new adjustment cups were needed.

On this I asked the machine shop also if I need hardened valve seats for unleaded/E85. They inspected the heads and said not necessary. Maserati heads have steel rings in the exhaust and any problems are very unlikely enough. They told that only problem in this sense has been Mercedes, which used cast iron ring in some engine. Those actually do break.

Well there is no reason valves shrink, these are not cheap 3 euros Mini valves. If they did not adjust lash caps this means they did not change guides, just a soft seat machining.
Why did you change exhaust valves ? Why only exhaust ?

I think these heads have problems : the springs are way to loose. 20kg seat load is very low for a boosted engine.

 

[henris42]

The pin was offset in the wrong sense, not enough space to fit conrods. Rubish.
Pistons are complex beasts.

Well there is no reason valves shrink, these are not cheap 3 euros Mini valves. If they did not adjust lash caps this means they did not change guides, just a soft seat machining.
Why did you change exhaust valves ? Why only exhaust ?

I think these heads have problems : the springs are way to loose. 20kg seat load is very low for a boosted engine.

Right, that head job was because I had blown exhaust valve (no idea why!). The shop very experienced, decades experience), said the Maserati exhaust valves had special surfacing, and recommended I get a new set. Intake valves were all bueno.

They still did full rebuild and inspected all, as we agreed replace parts only if needed.

We were bit surprised no new cups had to be ordered to fit the tolerance, I was all the time expecting that.

Is the piston this one: http://www.pistonispeciali.com/EN/index.htm ?

 

[alpa]

Is the piston this one: http://www.pistonispeciali.com/EN/index.htm ?

No as I said it was a custom design.
Their piston copies are OK. I've got their 2.8 pistons. I'm not sure of the ring gap they made: 0.35mm . To me it's not enough.

 

[henris42]

Sorry I was trying to ask was this the company?

You know we could make an open source parametric piston/rod/crank model... FreeCAD etc. You could easily check clearances. Would need some parts thought to model, I don't have extras.

 

[alpa]

Yes it's this company.
I think you are over optimistic about the pistons. Pistons are not round and not straight. There can be a gradient of 300C across the piston. A good piston company puts necessary clearances, it's their job. Then I give the main clearance to the sleeve machining shop and they machine (with the piston in hands to be sure of the size).

 

[henris42]

Yes it's this company.
I think you are over optimistic about the pistons. Pistons are not round and not straight. There can be a gradient of 300C across the piston. A good piston company puts necessary clearances, it's their job. Then I give the main clearance to the sleeve machining shop and they machine (with the piston in hands to be sure of the size).

In mechanical engineering those are called design rules, and they can be managed by software. Its 100% doable.

 

[alpa]

I don't understand what for.

 

[henris42]

Well, you are here offering all sort of parameters. You do not want to act upon them?

 

[henris42]

I do this to open things up, on these old cars. I'd publish the drawings if I had those.

I don't have much faith that I can make money, so open source is good. You can still make your own products.

 

[alpa]

Well, you are here offering all sort of parameters. You do not want to act upon them?

Act in which way ? Do you think a piston manufacturer would accept to machine your design ? Do you know the constraints of their tools ? Do you know the shape of the forged material they are using ?
And more generally: I know nothing about the piston design, I've been explained many times how complicated is this stuff and I believe it's true. This is what money is for: to let competent people do what I can't or don't want to do.

I prefer concentrating on the job I can do and that is poorly made most of the time. Every rebuilt engine I disassembled so far was badly rebuilt. Even searching for a company able to correctly rebore or replace a sleeve is a challenge. Don't think they are able to properly replace valve guides. It's a disaster. May be it's because I'm in France, may be.
PS: I've just realized the last engine was rebuilt in Switzerland. On one head the exhaust guides (cast iron 13.04mm in diameter, the factory ****) were inserted into tapered overbored housings, one was 13.15-13.10mm, two others were 13.10-13.05mm. So basically the guides held thanks to the low spring retainers and latter to the carbon deposit on the low part of the guides.

 

[alpa]

steering pump on the left side: done
It works very well, the car did more than 100km



This frees lots of space on the right side, the steeting hoses are shorter, the A/C compressor is easy to access.
There are few more mods, would you find them ?