ProMAX Level 4

[Mr968]

fix your brakes, upgrade your suspension

Couldn't agree more with this, not forgetting that you didn't know what bhp car you had,(sorry) it sounds like excessive mods to the engine would be a step too far for you at this stage.
First Brakes.
Upgrade your brake hoses to Goodridge, get some decent brake fluid in and some performance pads, make sure your calipers are working correctly, that will get the brakes sorted, which is the first thing you should consider and is usually the cheapest upgrade and usually you can do it yourself. You could also go for bigger calipers but then that starts to cost hundreds.

Then Suspension.
Make sure that your current suspension is as good as it can be. Preferably change to Koni Sport dampers(that doesn't mean M030). Or if contemplating going on the track go for KW.
You might consider changing the bushes to Powerflex.

Then Engine.
Before you do anything, as mentioned I'd make sure that you have an engine that is sound before you do anything. Have it rebuilt if necessary to achieve this with strengthened/new components. You are worried about costs now, imagine how upset you would be if the engine blew up.

Do the mods as listed above in that order for the most cost effective performance upgrades, and on the way do the research and talk to people like Fen and the others on here about engine mods.

(Fen, yes the option code for LSD was L220)

 

[AndrewS]

ORIGINAL: 333pg333
...Maybe it's too hard to go up in cc's, but maybe not. Just do a little research and you may find that it's not out of reach and you will be struck with the difference.

Hi All,

The 'easiest' way to achieve a capacity increase (2.5 to 2.8) is to go for a 3.0 litre crank (968 or 944S2), this will fit the 944 2.5 block and achieves the 300cc increase as a result of increased stroke. Another way is to use a 3.0 litre block with a 2.5 crank (2.7) or to go to 3.0 litres and beyond (3.0 block and 3.0 crank or wet/dry liner machined block from any 944T or S2/968).

All the above require fairly extensive surgery and I know from experience that a £6k engine build project can quickly become a £14k one (this was 8 years ago when I built the 2.8 and my estimating skills are probably a little better now). For an increase in capacity the engine really needs to be removed. After at least 15 years, many parts and ancillaries will be on their last legs (the brittle and fried wiring loom is a good example) and will simply need to be replaced. As the engine is out, it makes sense to replace the clutch assembly, water pump, oil pump and starter. You will probably want to examine the turbo as well. All this can result in the cost exceeding your original estimate. Get the picture? The extra parts (crank, block possibly, oversize pistons and forged rods) will also push the cost up.

On an '86 car it would be possible just to install the crank and use either different pistons or rods and complete the job at little cost (assuming everything else was useable) - it could even potentially be done with the engine in the car (not recommended). However, it would still be quite expensive compared to a Level 2 kit (for example) which will give a dyno proven 300+ bhp. A 2.8, 2.7 or 3.0+ is a good basis if you think the cost justifies it and you plan to use the car for a long time. Again, don't overlook the cost of bearings, gaskets, fluids, filter etc. and labour when considering this.

John D's 2.8 has lots of low down power that is very noticeable on the road and I am sure Paul's car is the same. Cubes are great - but performance is ultimately governed by how quickly and efficiently you can get air into and out of the 951 engine. The larger the capacity - the harder it is to get the most from it (using 944 Turbo engine & tuning parts). I agree that it would be theoretically possible to get 500bhp from a 3.2 litre and I am sure we will see a 944 Turbo break that threshold soon.

Regards,
Andrew

 

[Fen]

That's all correct, but if you spend the money refreshing all the bits that are on their last legs you're geting back to a point where you have a good solid base, which is a desirable place to be as a platform to further tuning rather than build on the ropey old bits hoping they won't break if you don't touch them.

It isn't disturbing them that makes them need replaced after all - you can disassemble good parts without damaging them so if it falls apart when you take a spanner to it then it must have been knackered anyway.

 

[AndrewS]

How much extra on top of the L4 would a rebuilt bottom end cost? As Fen rightly points out anyone considering this package would want to start with the best base engine they could. My motor's done 160k & is okay as standard but probably pretty tired & if pushed might pop. I'm sure you'd check the unchanged parts over but if (hypothetically) I wanted to do this but my bottom end wasn't up to scratch is there another option?

Hi Malc,

All depends on what needs to be replaced. At 160k, there may be enough wear on the crankshaft journals to justify going to the first overgrind. Its possible that new rings would be required (worst case a 100.5mm overbore and new oversize pistons). All this starts to add up (especially from a labour perspective) and if the engine has to come out, it is false economy not to replace other wear and tear items (such as clutch assembly etc).

So, another option [1] is starting with a freshly built exchange engine. The cost of which would depend on what specification was required. A straight forward short block 2.5 Turbo that is to the same tolerance as a new factory engine would be all that is required (other than we would use Pauter or Carillo connecting rods) to support a ProMAX L4 solution.

Another option [2] is putting in an GM LS1 engine (V8 Corvette, Monaro etc). 400bhp in standard trim and more torque than most would ever need (5.7 litres up to 7 litres). We often toy with this idea, but still haven't got round to doing it. That's another debate in itself ;-)

Regards,
Andrew

 

[Guest]

ORIGINAL: Fen


Are you actually trying to start an argument?

???????? No - I'm actually giving my opinion in a response to what you posted.

 

[Fen]

ORIGINAL: 422bhp944

ORIGINAL: Fen


Are you actually trying to start an argument?

???????? No - I'm actually giving my opinion in a response to what you posted.

You do that by suggesting that I am singling ProMax out when in the very same post I took the time to specifically apply my comments to any tuner despite the fact the thread is about ProMax?

 

[John Sims]

ORIGINAL: AndrewS

.......The 'easiest' way to achieve a capacity increase (2.5 to 2.8) is to go for a 3.0 litre crank (968 or 944S2)......

Not trying to be argumentative but there must be more to it than that. Wouldn't just changing the stroke up the compression ratio dangerously? This must be allied to different pistons or head work surely?

 

[AndrewS]

ORIGINAL: John Sims
Not trying to be argumentative but there must be more to it than that. Wouldn't just changing the stroke up the compression ratio dangerously? This must be allied to different pistons or head work surely?

Hi John,

There is light machining of the block interior, but otherise that statement holds true. You either use pistons with an offset wrist (gudgeon) pin or, different length connecting rods. On John's 2.8 I used only a 3.0 litre crankshaft and shorter length carillo rods - the pistons were standard 100.5mm oversize. The extra throw of the crank increases the swept volume - hence, the capacity increase. The rest of the car's engine was the same as a 2.5.

Regards,
Andrew

 

[AndrewS]

ORIGINAL: Fen
That's all correct, but if you spend the money refreshing all the bits that are on their last legs you're geting back to a point where you have a good solid base, which is a desirable place to be as a platform to further tuning rather than build on the ropey old bits hoping they won't break if you don't touch them.

It isn't disturbing them that makes them need replaced after all - you can disassemble good parts without damaging them so if it falls apart when you take a spanner to it then it must have been knackered anyway.

Hi Fen,

The point I was trying to make is that it would be false economy to remove the engine and not replace items like the clutch and oil pump (for example). For example: the labour to do a clutch is over 10 hours, but its 30 mins with the engine already out (times are very approximate).

My point is that the overall project cost of replacing the short engine is possibly well beyond just a simple remove and replace cost (as well as the cost of the rebuilt engine). So, for some it may be prohibitively expensive.

For the L4 kit, it is suggested that the car must be in good shape to begin with. However, the 951 engine is a very well engineered piece and it is possible to safely run the engine to produce considerably more power and still achieve acceptable reliability and durability (providing that all aspects that restrict power are addressed). Whilst there is benefit in moving to a higher capacity engine - it's not necessary to make power. If the air can be pushed through the engine and the volumetric efficiency maintained - power can be made (remember the F1 turbo era in the 80's? - very small capacity engines, massive power!).

A solid 2.5 short engine is fine to use as a base. If the owner has concerns about the integrity of the engine - it can be overbored & honed (& the alusil reapplied) along with fresh rings (& pistons if necessary) and beaings etc. I don't disagree that a well deisgned and built large capacity is the way to go - but the standard 2.5 is a viable alternative.
[]

Regards,
Andrew

 

[333pg333]

I haven't seen any cold figure$ on a V8 conversion, but I'm betting it would work out cheaper and a lot less stressed for the same amount of power in the long run. You would change clutch, pp, bearing and you well may need to upgrade CV's and axles plus decent LSD. Everywhere you look when modifying these cars has a reaction down the line.
If I had known then what I know now I could have just bought a decent 2nd hand GT3 and be done with it. [][][][]

 

[sawood12]

There is alot of talk here about stressing the bottom end. Not sure exactly what is meant by this and although I do completely and utterly agree that if you are going for big power hikes then you are better doing some work to the bottom end of the engine (you'd be crazy not to), however there is one point that is maybe being missed here and that is that when Porsche designed the engine they probably used a factor of safty of about 5 or 6. A factor of safety of 3 or 4 is usually the absolute minimum manufacturers use (they tend to use that in the civil aerospace industry where weight is all important at the current fuel prices) and with Porsche being how they are they are bound to have upped the usual factor of safety in their design, therefore this means the engine is probably at least 5 or 6 times stronger than it needs to be at stock power levels, which means you can double the power and still have a factor of safety of 2.5 to 3 times - i.e. 500bhp. To back this up there are plenty of people who are running decent power levels - and I mean around 300bhp and not necessarily upto and around 400 bhp, perfectly reliably without having carried out the extensive refreshing of the main engine parts. You should be pretty confident about running upto 300bhp with a decent kit that controls AFR's well. However as soon as you start to head well into the 300bhp's then of course you are wise to carry out more substantial preparations.

So those with the Promax level 2 kits or Vitesse kits should not feel too aggrieved that they didn't spend £5k on an engine rebuild before installing their kits.

 

[333pg333]

Don't disagree with your sentiment here Scott but those stats are based on a brand new engine, not one of our agegroup. I'm not saying that you can't have success with one of these bolt on kits, but even Porsche parts wear.If you all want is a few extra horses then you are much safer than when you approach or become a full fledged member of the 400+ club. I also think 350hp is still a very quick car.

 

[Diver944]

So H4x0r7000, have we cleared that up for you?

 

[Fen]

I agree you don't need a rebuild to go for the minor gains up to 300bhp or so - they're easy to get and you can do it on the original fuel and turbo components. Going much further is a different story though as you increase the stress on anything worn or weak for any reason and you also accelerate future wear on something already worn.

I'm not sure I agree with your theory on the safety margin Porsche built in. Consider the development that got us to the 944 Turbo: Porsche want a "better" version of the 924 to add to their range. They look at new engine options and eventually settle on making one out of half the 928 V8. That 928 V8 made around 300bhp across 8 cylinders and the 2.5 NA 944 made 160bhp out of 4. I'd say that means some components (pistons, rods) get the same stress levels as in the original 928 design and others like the main bearings get half as much. What fails on 944 bottom ends? Usually big ends or rods/pistons, which would seem to bear out that the mains are unstressed.

OK, so even if there was a 6 times safety margin on the 160bhp NA 2.5 engine's pistons, rods etc. the same basic design was pushed to 250bhp in the Turbo which therefore had under 4 as a margin. Now you up that to 400bhp and your margin becomes 2.4. As Patrick says wear erodes that margin. I think that explains why there are some engines running this power level on original bottom ends and some go bang. Note also that Porsche originally used forged rods in the Turbo then went back to cast, so there was a bean counter at work even back then trying to trim out unnecessary cost which would be achieved by making accepable cuts in durability.

I didn't thing 359bhp felt that fast, Patrick. I do think there's something wrong with me though because I have never been impressed by the sheer power of any car.

 

[nick_968]

Have to agree with you on that one Fen, have yet to go in a car that felt 'fast', was hoping to achieve it with mine but even at 450 I think its going to struggle....I drove a 450hp 996 turbo S not so long ago and that was quick but still not as fast as I hoped. I am hoping that with less weight and one big turbo mine will feel a bit quicker, if it can keep traction in the lower gears and not destroy the gearbox! At the moment its around 375 and the turbo is not coming in hard enough and it certainly doesnt feel quick yet. Still waiting to get custom IC and Rad before I go for the proper tuning session...!

 

[Hilux]

So, yes torque is important - but power is more important in a sports car. You need to have good torque to generate the power to begin with. Get a ride in Mark K's car and you will understand what I'm talking about.
[]

Mark..............calling Mark.................

When you`re out and about I`d love to see what its all about as I am planning a `mild` performance upgrade.

I tried (albeit briefly) Fen`s car and was smitten with the handling etc hence my suspension upgrade earlier this year. I`m a great believer in tried and tested scenario`s as I`m loath (lazy?) to be the guinea pig.

I`d love to get a ride in Paul`s too.

My race Westie only had 160 bhp but, without a Lim Slip (due to formula regs), often that was too much. The whole driving experience was balancing the available traction over power or more accurately torque.

Standard LSD`s arent all they are cracked up to be. Fine for doughnuts but they slip at the wrong rates for tight tracks and bends. I`ve had my 951 sideways without warning when accelerating out of a bend.

My Westy had an LSD and it would still drive you 90 degrees down the road [8|]

My 800kg V8 G27 had an LSD and so much torque it would lock the rear wheels when you changed down even when you matched the revs which meant that in tight corners you ended up having to accelerate early out of them [&:][&:]. Bl**dy thing nearly killed me with the LSD with cold tires when I managed to take out a lamp post and rolled it only 100 yds from a standstill, trouser filling and frighteningly quick though[8D].

 

[MarkK]

No problem[]

 

[333pg333]

I guess it depends on who's driving and where. Sometimes on the track your car can feel slower than on the road even though you know you're going much faster. When I was driven around Eastern Creek in a warmish GT2 it didn't feel blindingly quick but we touched 280kmh down the straight. Slick tyres through the corners just keep gripping so there's almost no perception of sliding about which also contributes to the perception of speed. Being driven by a 'Hall of Famer' didn't hurt either, though then when we climbed out and he took me around in my car it didn't feel so much slower either and that was only when it was at 300 hp crank...ish. I then got all excited and jumped in after him without checking the oil levels....8 months later and just a couple of bob spent, and we are fighting time to make it back to it's first meeting since on Saturday week. I'll probably forget how to get to the track!

 

[edh]

Fen - I'm sure there are cars out there that will hit he spot for you, although I doubt if 359 bhp will feel a whole lot faster than 300 in the same car.
It depends so much on the car - 145 mph through Fuchsrohe in the ring taxi felt reasonably sedate.

If fast is about perception rather than absolute speed, you need a passenger ride with my mate Kurt in his V8 Locost at somewhere narrow & tight like Cadwell. It's a very quick car anyway, but add in
a) It always feels faster from the passenger seat when you have no control over what's happening
b) It feels much faster when you're very exposed in a seven -type vehicle
c) All that V8 torque in a very light car slams you back in the seat (mind you, he's looking for a 5l RV8 to give him more power now [] )

 

[Neil Haughey]

Problem will be with peak cylinder pressures with respect to engine components in and near the cylinder and how suddenly the BMEP increases when one considers multiples of cycles. A careless tuner will tend to map things like the boost pressure to give a sudden big torque hit. This makes the car feel very fast but is really bad on everything else not just the engine internals such as trans, driveshafts, tyres, etc.. It also doesn't necesarily translate into a fast car.

What this all means is that an engine could be tuned to 300 Bhp and be unrealiable or it could produce much more power yet still be fairly reliable just based on how it has been tuned i.e. smooth out those torque spikes and a high power engine will probably still be pretty reliable.

I have no idea what the relative merits are of the options you guys are talking about in these regards though.