OK, This thing about turbo's and dump valves!!?? Can any of the wise members inform me of the following?

(a) What does a dump valve really do? - I know it dumps the excess air and makes a hissing sound in the process
(b) What would the benefits (and is it possible in the first place) be to fitting one to a multipla's JTD engine - it is already remapped to 155 bhp, would this improve performance?
(c) Am I asking stupid questions?

Your help would be appreciated....

Phil

I wouldn't bother with it.

If it has a dump valve it'll probably be a bosch or valeo recirulating plastic one with a spring.

I've done a few rolling road tests with a my Saab running 285 - 290bhp (at the time) with a standard Bosch and Baileys (£90) recirculating dump valve.

They make no difference.

Now if you really want to make a difference....you should go down the turbo upgrade route, but unless you're willing to spend around £3k including a completely revised custom map (£400 - £1200 depending on how much tinkering you want to do) and a few rolling road sessions (£35 each), I wouldn't bother.

I'm in the process of doing the same to my car and the cost is very high. On top of what I've mentioned, there's other things such as better fuel lines, bigger fuel pump, bigger injectors, improved air intake, end to end 3" exhaust with race/sport cat, bigger free flowing intercooler, custom made gearbox. I'll be sticking in a new Garrett GT3071BB turbo on top of all that...and the mods I've mentioned are just the tip of the iceberg.

It's a lot to do and if I bought all the stuff at normal prices it'd cost me £5000+.

I've sourced a lot of the genuine stuff from Europe and the US and some second hand and I'm on target to complete at a cost less than £3300.

Mind you, this will give a modest 450bhp

I don't want to disuade you from upgrades, but the rule of thumb is to optimize the inputs and output of fuel and air, along with cooling.

My plans for the Multipla are to review and improve air intake where poss. Install a 3" full stainless exhaust and sport CAT once the existing one dies and get a re-map done.

The free flowing 3" exhaust ... more importantly the downpipe section will give between 5 - 10bhp extra once the right ecu map is applied.

It's also worth noting that with extra power you'll soon tire of the braking performance (if you drive enthusiastically). Try fitting a set of Ferodo DS2500 pads instead of the replacement pads and if poss, pair them up with a set of standard replacement brembo discs. Once bedded in, the extra brake efficiency will be noticeable, even when cold.

I'm trying to source some Eibach springs and dampers as the car sits very high and it would benefit greatly if the handling could be improved. this will also get around the problem with the dodgy front springs.

Anyroad, I've wittered on too long.

Thanks Aeroadster, for all that. That's the trouble, once you start with the moding its difficult to stop!

I am looking to do the simplest things and get the greatest results! I am not looking to turn the Multipla into a fire breathing dragon, but, I do want it powerful enough to surprise people when needed. You know, the typical and universal idiot driver we all meet at certain points during the week!! Enough said!

I have got to say that the re-map has amazed me, the engine is so much more powerful, before this I had a 55 reg Honda Accord, 2.4 Type S, and I tell you, I think the Multipla is now faster, definitely more poke in third and fourth gears, the pick up is tremendous

Please keep me informed on the mods you carry out, you certainly seem to know what you are doing - I think I could learn from you

Have a good one

Phil

Phil,

Thanks for the encouragement.

I think given the tight engine compartment space it's going to be hard to seriously improve the power delivery significantly more than what you already have.

The limitations of the Multipla are the gearbox and clutch and they probably won't stand up much more power. Of course, this will depend on how the power is delivered.

IMO, the standard 1.9 already has a large amount of poke in 1st and second, although a slight increase in second would be ok.

I'm sure further gains could be had in 3rd and 4th with a 3" exhaust downpipe without major consequences to the clutch and gearbox.

I would need to have a look at the turbo used and it's configuration but I would imagine that 170bhp is possible with a 3" downpipe.

Forget K&N or any other type of air filter upgrade. It won't make a difference.

The cost of a 3" downpipe will probably be £130 - £200 depending on what's available. Ideally a full exhaust and sport cat would be great but that would probably cost £450 - £600.

54 Silver Multipla said:

OK, This thing about turbo's and dump valves!!?? Can any of the wise members inform me of the following?

(a) What does a dump valve really do? - I know it dumps the excess air and makes a hissing sound in the process
(b) What would the benefits (and is it possible in the first place) be to fitting one to a multipla's JTD engine - it is already remapped to 155 bhp, would this improve performance?
(c) Am I asking stupid questions?

Your help would be appreciated....

Phil

Click to expand...

Hi,

There is no dump valve on the JTD and adding one will not have any advantage other than a "Tscccc". Also it has to be spliced onto the brake vacuum line to activate the Tscccc and so isnt a "real" dump valve anyway. Turbo charged diesels work in a different way to turbo charged petrols, and simply dont require a dump valve. (ie no throttle butterfly that closes off during gear change requiring dump of excess boost) The air circuit into the turbo on the JTD is a rather long and bendy one, and power gains can be made from upgrading this. If your running 155bhp now with just a remap, with a better air circuit (induction kit) I would estimate at least a 10bhp gain. However it would have to be the "right" induction kit and not just any old bolt on type.

Alan

That's all very interesting a1ant, thanks very much, but this now begs the question, what is the "right" induction kit?

Cheers
Phil

ooooooh this thread is getting VERY interesting:yum:

Emm said:

ooooooh this thread is getting VERY interesting:yum:

Click to expand...

My thoughts exactly!

Phil, just out of interest what chip have you fitted?

Hi mjb,

I had a Angel Tuning re-map to 155 bhp (Was 115 bhp) Cost £300.00, but, for the performance gains it was most definitely worth it. The car is now even more pleasurable to drive.

The clutch is not an issue at the moment, everything good

Phil

I would recommend doing a rolling road session with a reputable company to find out how your existing map is performing.

Perhaps angel could provide the info if the re-map they sold you is "off the shelf".

An expert can easily tell you whether there's any limitation in the existing map e.g. lean mixture occuring when etc...and what this means for you in terms of performance.

Until this is done, it's had to speculate where the money is best spent next.

I don't know enough about the workings of the Multipla ECU and whether it's designed to acknowledge changes in the inputs/outputs and adapt positively to them.

The idea behind an improved air intake system is to try to get more cooler air to enter the system. However, this may not make much difference if the rest of the air intake system e.g. delivery pipe is sufficiently large enough to not make much of a difference.

I haven't inspected the multipla enough to know what the design limitations are, if any.

Take for example (again), my Saab 9000. It's currently delivering 55 - 60bhp and about 60 - 65lbft more torque than normal as mentioned previously.

By making airbox mods (e.g. drilling or adding a custom air intake system) and increasing the size of the delivery pipe from 2.5" to 3", it makes no difference to my existing map. I do get a nice throaty noise when I put my foot down.

It's currently got the standard Mitsubishi TD-04 15L turbo bolted on.

Now, I can do some more tweaks and get to the limit of the turbo, but short of me bolting on the Garrett GT3071BB turbo, I'm not going to get any benefit from the air box mod or a bigger delivery pipe.

However, changing the downpipe which is a known restriction on the 9000 and installing the Abbott Racing downpipe which allows the exhaust gases to flow more smoothly and quickly, I can get a lot more from the re-map.

Likewise, replacing the standard intercooler with a bigger and more free flowing Abbott (Mace product in disguise) intercooler, I have improved my bhp and torque figures again.

In this situation, the engine cooling and exhaust end were more the limiting factor than the air intake. From many other Saab modders that i've met or know about, the air intake is one of the last things we would do when looking for a value for money route towards increasing power.

Fortunately, there are a number of expert Saab motorsport tuners in the UK who have a wealth of info on this kind of thing. Irrespective of what car you're starting with, the same principles apply.

I'm too new to fiats to know who are the real experts in Fiat tuning.

A measure of a good ECU re-map/tune is a rolling road report.

This forum hold regular rolling road days at a place called Red-Dot. Its located in Watford in Hertfordshire just outside London. They also provide a re-mapping service where you get before and after rolling roads. There are many JTD's on this forum that have been re-mapped and have custom indution kits, but most tend to be punto's, stilos etc rather than the multipla.
The JTD responds very well to tuning and is actually a very tough engine. The internalls are strong and capable of much higher power output than they come with as standard. As has already been mentioned in this thread, the limiting factor with the JTD's and Multijets at the moment is mainly the clutch and gearbox.

With reguards to the induction kit, GSR (who are also at the RR days at Red-dot) provide custom made induction kits that have been tested to prove the gains, unlike the generic K&n kits etc. Many JTD and Multijet owners on here are running either Angle Tuning or Red-Dot remaps with GSR induction. The GSR induction basically replaces the pipe from the turbo to the airbox (2x 90degree bends) and the airbox itself and straightens it out and takes the filter further away from the engine for greater and colder air intake.

The exhuast system on the JTD is fairly restricition free, and as such, most JTD owners dont upgrade the exhuast (except maybe a sporty sounding back box) as it isnt really a limitiong factor untill you start hitting big horsepower.

Alan

You know, this forum is full of really useful people who give useful advice

Thanks again to aeroadster & a1ant for their valued comments.

Funnily enough, I grew up in Watford...

I will look into the GSR conversion and also speak with Angel Tuning on possible further gains. I suspect, with the GSR induction, the map I currently hold will need to be tweaked!

I now have a much better understanding of what the limitations/possibilities are to tuning the old Multipla and I thank all for their advice and guidance.

Perhaps the best route would be:

(a) Induction (GSR)
(b) Tune re-map, re-map the re-map:idea:
(c) Source a stronger clutch - Once this one goes
(d) Change engine oil more frequently!
(e) Look into new suspension

So what else can we do with the Multipla (yet keep it sheep'ish' looking?)

I have just purchased some new rims (16" stilo abarth), will have them refurb'd next week and will put new rubber on.

Will post some pictures later in the month and hopefully get to meet and discuss things with all the guy's that have contributed in person at some point down the line.

Phil

It's good to know there's a tuner and rolling road in Watford too as I'm only over in Barnet.

The other fave Saab mod is a rear piggy back ARB (anti roll bar) mod.

Although you can buy kits off the shelf for some cars, I've simply bought an old rear ARB, chopped the small ends off them, then made four of my own aluminium alloy clamps and clamped the the second bar to the one on the car.

This significantly reduces body roll.

I know this works for many cars, but again...I've not inspected the multipla for suitability so if you're not sure get it checked out first.

I've also done front ARB mods too and where poss upgraded ARB bushes to polys.

There was talk about finding soe generic Powerflex purple poly bushes for the multipla but I've not seen any follow up on that yet.

Remember, if you want to improve your braking performance, think about the Ferodo DS2500 pads. I'll look up the part numbers for you if you like.

I've negotiate special discount prices for UKSaabs forum members through a company called ASP oops north and I've asked them to see if they will do the same for us too. Prices to follow in the next fortnight - if no one objects.

At the end of the day, I would get super-beaten down prices anyway...so it's just nice that other people can benefit from it too. As an example, they are about 10 - 15% cheaper than the cheapest UK supplier for the same pads.

As A1ant says , dump valve is to help prevent stalling of the turbo on petrol engines and rid of the hot waste gasses so the turbo can spin down at its own rate .
Dump valves offer no gains on any car but just aid the way they work and angel tunning will have taken your multi out(yes?) and set the map whilst driving so they could set the power at what they thought best for your individual engine and the long life of it rather than giving you max power and having a smokey car.Another intake suggestion would be BMC carbon box which is similar to the GSR but an upgraded panel filter from K&N is an upgrade on he standard and does work better than the usual bolt on cone flters, see so many cone filters bolted on right next to the manifold
it decreces the power. One of the best upgrades i think ill be going for is to remove the egr system as it puts hot gasses back into the inlet as well as sooty oily smoke.

gsr induction kits make jtd engines sound alot better, can loudly hear the turbo hissing and when you let off the gas at about 2k revs when just driving normally it gives a nice 'tish' sound just like a dump valve, sounds ace, i could possibly try and get a video if you wish.

Hey Beau - That would be great, do it!

i tried to get you a video but you cant hear it in it, but all it sounds like is a dump valve!