turbo mods

[stevejohnson]

I have had my '89 turbo for 1 year, very enjoyable. Have read on this forum about about modifying it to make it more driveable. It has done 123k and uses a bit of oil (1 litre every 500 miles or so) so I don't want to overly stress the engine. Is there a 'sensible' and relatively cheap mod to increase power and reduce turbo lag? Should I get a compression test before doing anything? Who would you get to do the work? (I live in Kent)
Also has anyone put Swepco in their turbo gearbox? I put it in my '83 944 lux and it made a big difference (it lost it's previous 'stickiness')

 

[Diver944]

Hi Steve, the first of any modification to make with the 944T is to reduce the amount of lag caused by a weak factory wastegate by fitting a boost enhancer http://www.promax.eclipse.co.uk/boost.htm £100

After that you can fit a set of chips and 3bar Fuel Pressure Regulatordesigned to safely increase the fueling to match an increase in boost from 0.9bar up to 1.1bar. The boost will drop away at higher RPM because of the inherently weak wastegate £250

After that it gets a bit more involved [] and before you go any further its best to make sure your head gasket is recent £800

You can then replace the factory wastegate with an aftermarket design from TiAL ( www.speedforceracing.com) or Lindsey (imported by Promax) £400 which will enable you to hold whatever boost you want up to the redline. At this point you also need to address even more fueling, charge cooling and a better air metering method than the standard airflow meter ££££££££

 

[sawood12]

Steve, As Paul has already suggested the wastegate and boost control system is the first place to start. I've got the Promax level 2 kit with the boost turned upto 1.05bar from the standard 0.75 - 0.8 bar level which is considered a pretty safe level for an otherwise standard engine. The chips from this kit bring the boost in earlier which improves lag but doesn't eliminate it. I'd say it basically takes the sting of the boost making the car more drivable. I would recomend considering replacing the AFM with a MAF as well. It is a mod on my list when cashflow allows. There is the plug and play SciVision system that replicates the standard AFM signal and is a plug-and-play solution, however i'm increasingly becoming tempted by the Vitesse Racing set up that has a piggy back computer for massaging the fuel injection. This system is free from alot of the downsides of the standard AFM/ECU limitations and is tunable by yourself via a laptop if you feel brave enough.

As Paul says be prepared to spend some cash as what starts out as being a seemingly modest aim almost always turns out to be a pricy project. It is fun and very satisfying though.

 

[pauljmcnulty]

Hi Steve,

Swepco, yes.

Mods, just a small caveat from me without wanting to sound negative.....[8|] If there is any doubt about the strength of the engine then it would make a lot more sense to start from there rather than spend money on upping the power only to cause more problems than you fix!

 

[sawood12]

Your oil consumption does sound higher than the level Porsche say is OK which is 1ltr per 1500km's so in that case it is definately advisable to get the engine checked out to see where you are loosing the oil.

I've got Swepco in and it seems fine but noticed no difference in the operation of my gearbox. From threads on other forums though I think Redline is better and i'll be giving that a go next time.

 

[John Sims]

A number of forum users seem to have had consistently good results with the Vitesse MAF system, I believe the SciVision is less "Plug and Play" than has been suggested.

I use a MAP system by Link in NZ. This is far from brilliant, and very difficult to set up, but has the advantage of being unaffected by boost leaks. As far as I'm aware the only other MAP solution is via stand alone engine management.

Paul's initial summary makes good sense but, be warned, once you start it is an inextricable slide to abject poverty.

 

[Suffolk944]

My first mod was the boost enhancer and I certainly found made a considerable difference in the power delivery (though not output) for a relatively modest outlay.

Last year I decided wanted to get rather more oomph and got the level 2 Promax kit fitted which I have been very pleased with. I also got the vacuum lines replaced which I think was good investment.

It is a slippery slope though - now after just around 8 months after the last mods I am contemplating whether I can finance the next set of changes by selling one of my kidneys []

BTW I still have the now not required boost enhancer if anyone is interested.

 

[stevejohnson]

Thanks for your advice everyone. It is being serviced at the moment. There were some leaky seals which will be replaced so if the oil consumption goes down I shall set foot on the slippery slope by fitting a boost enhancer. Also, some swepco on order for garage to stick in gearbox tomorrrow.
Thanks again.
Steve

 

[Andy97]

1. anyone got a web address for promax near Silverstone, I can't seem to find them anymore?
2. excuse mu ignorance but what's Swepco and what is supposed to do?

 

[Suffolk944]

Andy97

Their web addy is http://www.promaxmotorsport.com/

They have just moved to a new workshop near Milton Keynes.

 

[sawood12]

ORIGINAL: Andy97

1. anyone got a web address for promax near Silverstone, I can't seem to find them anymore?
2. excuse mu ignorance but what's Swepco and what is supposed to do?

Swepco is a gearbox oil. An be warned it is bright blue in colour. I got a bit of a shock when I opened the can and wondered if I bought the right stuff.

 

[poprock]

ORIGINAL: DavidL

"¦ you pay much more for far smaller gains as you go up?

That's my understanding of it, in a nutshell.

Eventually, the law of diminishing returns kicks in.

 

[Suffolk944]

Yes thats how it works I am afraid ! It's why I have not (yet) gone for a full L3/S3 kit as I struggle to see how the much higher cost of such kits can be justified for road use, especially here in the UK these days where the opportunities to deploy all that extra power either because of traffic levels or cameras is frankly pretty rare.

If I shelled out an extra £2-£3k for another 50 HP I would want to be able to use it on a regular basis !! If I was tracking/racing then that would be a different matter, but for UK road use I honestly don't think that either the extra cost nor the extra HP of a S3/L3 kit is worth it. My L2 kit plus MAF and EBC gives more than enough extra performance and improvement of power delivery over the standard set up that I will ever really be able to use regularly on the road IMHO. Doesn't mean I will never go down the route a bigger turbo etc but its not as high on my list of priorities as it once was.

 

[sawood12]

The stage 2 kits tend to focus on mapping and squeezing a bit more boost pressure out of the turbo. Quite simple really - the low hanging fruit of modding. What they tend to produce is more power and torque but all at the top end due to the mechanical constraints of the stock hardware. The Stage 3 kits address that - so yet again homing in on headline power and torque figures is only telling you a small percentage of the whole story. If you drove a stage 2 car and a stage 3 car back to back I think you'd be very surprised to learn they are very different animals despite their close-ish headline power and torque.

 

[Suffolk944]

All true but again for use on UK roads I just don't think you are able enough to reap the additional benefits of L3 kit to justify the outlay. That said as I now have everything for a L3 kit other than the new turbo its always at the back of my mind that I should really do it one day, just for the sake of completeness you understand ! []

 

[sawood12]

Jon, I agree which is why i've said before that you are far better off spending money on chassis mods - mainly suspension and brakes, as that will unlock real performance improvements that you can exploit in real world. I installed my Promax L2 kit before the KW and though I noticed an immediate performance improvement with the Promax kit it was limited to straight line blasts down dual carriageway slip roads and overtaking on A-roads. In terms of B-road getting from A to be B use the performance improvements were largely redundant as I was still on saggy 20yr old suspension and didn't ahve the confidence or skill to push any harder than before the Level 2 install. As soon as the KW's were installed it was really like stepping into another world, cornering speeds were significantly increased by 20 - 30mph on some bends known well to me when weather and traffic conditions allowed, and I could brake later and harder and get on the power earlier.

The benefit of a new more modern turbo is not really the extra power and torque - it is the behaviour of the power delivery it brings. They will get on boost earlier, stay at max boost longer and performance will not drop off as aggressively when you get to the upper rev ranges. More power and torque will be available earlier in the rev range and you'll have it for longer. This will change the powerband from a more peaky stage 2 characteristic to a more mid-rangey and wider powerband.

I'm not saying they are worth the money, but that is what the extra dosh will buy you. Personally the state I had my car in before I sold her was more than enough for my and my driving abilities. If I was doing more trackdays then I would have probably justified more spend on her - i.e. a Vitesse stage 3 kit, but for the road I think I hit a sweet spot with he Promax L2 kit, KW and Big Blacks. More power than you'll ever need and the suspension and brakes to take it.

 

[DavidL]

Thanks all.
I think that has clarified my mind. As Scott says I can (almost) have a set of KWs and an S2 kit for the cost of an S3 (even the one I've been looking at) and that combination will almost certainly reap more rewards than the bigger turbo. My car will almost certainly not see a track so no gains there either.

Thanks David

 

[DivineE]

Turbo tuning is literally what I spend my life thinking about, wasting money on. The trouble is as you aim for bigger figures more and more parts become problem points. Dependant on condition and which dyno you go to a standard 250bhp car with a chip, 3.0bar fuel pressure regulator and boost controller will produce somewhere between 290-315hp. This is because the standard injectors, turbo and air flow sensor are all at their maximum at this point.

To go safely further than this you either have to go to a dyno for the day and get your car mapped to the modifications you have (because the air flow sensor is reading maximum flow but airflow is still increasing so fuel has to be increased manually based on RPM by looking at the mixture).

Or like you say you can spend £1500 on a MAF sensor and pigyback. ..but there's really no point doing that without changing the injectors because they are at their maximum flow. The turbo also is getting increasingly inefficient at this point so is producing more and more heat which reduces air desity and so power.

So then the rule is if you really want to go much over 300hp with a 944 you will need a lot more money to get those smaller gains. There is a slight cheat to be had though. I once went out in a car with just a chip that was running 311hp and 380ft/lb of torque. This is because torque isn't limited in the same way as hp by those components. Now that car was QUICK (I wonder if its still on here somewhere 'maroon' red' F** ***) and power was achieved by shimming the wastegate and bypassing the cycling valve so the wastegate control ran straight from the boost controller to the wastegate.

Andy from Fernsport looked after the car so I'm sure its condition was good and it wouldn't have had any leaks but it had run that power for two years reliably on nothing more than a promax chip. I don't think you get a much quicker car without spending a lot more than the £2k you suggest and it is what has inspired me to have a go at the standard route this time.

 

[Diver944]

I think Scott has hit the nail on the head because the difference in the headline peak figures is not as dramatic as the extra urge and refinement you get throughout the whole rev range due to the MAF unit and modern turbocharger. It's those two pieces of hardware that really add the £1000's to the price over a simple chip and raised boost.

I would always take the headline figures quoted by tuners with a pinch of salt but all of the above kits are similar in claim and price but they can't really show the huge difference they make to the driveability, extra response and reduction in turbo lag. It's only when you drive such a car that you realise the enormous leap forward that a better Turbo and MAF kit will bring you.

The only grey area is whether you can justify the extra expense in your own mind []

For me it all boiled down to the fact that I love 944's. I love the useable 2+2 practicality, I love the huge useable boot and I love the balance and way the chassis handles. To get the same performance from another Porsche I would have to spend tens of thousands and move to a 996 or 997 era car which simply don't have the practicality I already have

 

[Suffolk944]

Yes indeed, my MAF has made a huge difference even with the standard turbo, I have just gone about the changes bit by bit as budget allows and then the expense doesn't seem so bad as it doesn't all arrive in one big lump ! []