New car and a long list to start on!

[sawood12]

Large capacity N/A is a very unsophisticated and lazy way of achieving power. The larger the capacity the less efficient the engine. Recuperating lost energy to pressurise the intake air provides a far far more efficient thermal cycle and much more efficient engine. It is stone age vs space age!!

 

[pauly]

ORIGINAL: DivineE
however that doesn't stop the possibility of installing a set of 3.0 liners in a few months to improve the drivability with the existing package I'm installing now

Seems a no brainer if anyone has bore issues but I don't think a price has been revealed yet ?.

 

[bazhart]

I appreciate that some of you are waiting for a price to fit liners - and am sorry I have to hold back at the moment because we are only just in the middle of fitting the first set and need to find out the full implications before working out a price.

For example we need to skim the top of the block after fitting - not because we cannot make them accurately enough (we work well below 1 thou (0.025mm) but because the orginal block top will not be flat any more. That in turn requires the old studs to be removed and raises the question what to do about their replacement.

On the existing 3 litre we changed it to fit the head a different way without studs - but right now are still weighing up the options for the next engine.

Then we have to calculate the difference between the customer removing those studs and just wanting liner castings fitting to - at the complete other end of the scale - us receiving a car - removing and stripping the engine and rebuilding it and getting it running - to which you cannot avoid the added complication of new shells, crank-re-grinds, belts etc etc.

Which pistons to fit and do we supply them or not is another complication.

Hopefully you can see that we are not trying to avoid the issue - it is just a little early to set out prices - but as a clue - if we received a block without studs and just fitted 4 liners and skimmed the top - it would probably be about £2000 + vat (possibly eventually a little less if volumes increased).

We have not done this really as a commercial venture - just as a technical exercise to help internal development and interest - like the first 3 litre turbo we built. Our commercial interests are more linked to the Boxster and 996 (and more recently the 997) engine problems and we are that busy (and likely to get more busy) doing that - we would be silly to underestimate the cost of this venture and mislead people about it - when it does not form part of our main future investment plans.

We are going to build an interesting next car but more to learn and find out - for the whole Hartech team - than for anything else.

But having made the pattern for the cylinder castings - we did so to enable it to fit any 944.968 block and any bore size - so - if anyone was interested - we could use them - but I don't think it would ever justify our investment or become a viable venture - more an additional interest and some extra work to help keep these old cars running by replacing one liner for say £600 when an otherwise good engine has seized and good blocks are no longer availble.

Baz

 

[zcacogp]

Baz,

Thanks for this. I have followed your thread on PH with some interest, and was asking about prices over there as well.

Out of interest, what would be your preferred starting point for such an engine? On PH you said that a 968 engine would be best as you could then use the 968 pistons and crank. However, this leaves me a smidge confused; the 968 is 3 litre as it is, therefore why would you need to fit the liners?

You also used a 2.7 cylinder head for the first 3.0 turbo engine you built. These are a little rare, and you suggested that it might be possible to use a turbo head with some alterations. Was there any more progress on this?


Oli.

 

[bazhart]

Hi zcacogp, I think any confusion has come about because of the two different projects we have been involved in.

1st as simple and inexpensive as possible increase in capacity from 2.5 to 3 litre - for a turbo engine - which is probably easiest to do using a 968 block because you get the crank, pistons that can be modified and - if you can find one - a 2.7 head fits OK and the rest is relativley easy and inexpensive. This resulted in almost as good a performance as the 968S for little money and a nice smooth fuss free drive - ideal for a road car.

2nd - if you seek a more powerful engine we have since recognised that heat generated is/could be a problem as you increase output and that the older 2.5 block has a different coolant depth and double water pump inlet - and this will help us. We also will be using different pistons because I don't think the 968 pistons has enough taper - or after it has been dished out to lower the geometric C/R has enough crown thickness to take the increased cylinder pressure - and anyway cost becomes less of an issue if you are planning for 500 odd bhp. Fitting liners to this block may be more expensive than using a 968 block but we feel is right for the results we seek.

A 944 S head could be fitted to the std 2.5 turbo block if anyone wanted a 16 valve version. The shortgage of 2.7 heads however means that if someone had an existing 2.5 turbo - and wanted to fit special pistons, it may prove cheaper and better to liner that block and use the standard head than to find a 968 engine and a 2.7 head. How important it is to achieve the additional cooling is contentious - probably because no one thought about it before and are defending their position. We think for over 400 bhp it may become crucial. You can always get round things like this by increasing the radiator size but this doesn't improve the temperature differentials inside the engine. It is the extra power we want to squeeze out of the engine that has encouraged us to do all we can to improve the cooling beforehand - we have both blocks but prefer to do it this way and that has resulted in - as a spin off - availability of liners - if anyone has a use for them.

The 2.5 head can be modified to be roughly as good as a 2.7 head.

We have done an unusual different way round solution for this second engine - because we have modified the 2.5 block to accept a 968 head and are fitting liners to increase to 3 litre.

Our main reason is to improve exhaust flow (it is easy to blow in more air but getting it out is not so easy and increased back pressure reduces inlet charge efficiency and makes torque drop off).

We hope to use a variable inlet manifold pressure system on the waste gate and if so we already suspect that we would like to run with negative valve overlap at high boost pressures and delay the inlet opening as we increase manifold pressure and the variation in cam tining we seek happens to be the amount the variocam moves the inlet timing. So by altering the position of the sprockets we can achieve both the timing and increased negative overlap that we suspect may be restricting many other examples outputs.

Of course we may be entirely wrong but we are building a single cylinder dyno test rig to test out various permutations before we finally fire up the beast. The engine should be together in about 8 weeks but then we have the task of building it into a suitable racing chassis. While the chassis work is going on our single cylinder test rig will start - so it should work out OK.

The single cylinder testing is a route I followed successfully before with two strokes and the good result is that it exagerates the influence of different settings making it easier and quicker to zone in on the right settings (and only one piston to repalce if you get it wrong). It will also give us a clue to the stand alone computer settings before we start on the big engine and get Wayne to finally sort it out for us on his dyno.

We intend to use two wing mounted side radiators to allow room for a large intercoler and oil cooler in the front centre, to fit large brake cooling ducts, wider arches and wheels etc - so it is a big project and will probably not be completed until about a years time.

Baz

 

[zcacogp]

Baz,

Thanks. I didn't realise there were two such projects on the go, and hence was confused! Thanks for clearing it up.

From that which you write, it sounds as if the first project is the one that is complete and operational; is this the one that people on here and PH (Paul Smith, Ben Burt etc) have driven, with the very enthusiastic reviews? If so, it sounds like the only modified (or not-off-the-shelf) parts required are the 968 pistons, with a larger dish machined out to lower the CR. Does it also run different chips/wastegate/boost control? (Here I am unsure of the details, but they are the parts the turbo boys seem to change to improve performance).

You also say that it has "almost as good a performance as the 968S". I thought that the performance of the 968's were (broadly) on a par with that of the S2, and hence would expect a turbo to be quicker, and a modified turbo to be quicker still. Have I misunderstood something?

Apologies if these are numpty questions. I seem to be very good at asking them ...


Oli.

 

[AndrewS]

Hi Oli,

I think Baz is possibly referring to the 968S (as in Turbo S) which had a 3.0 LITRE turbo with 8v head.

Regards,
Andrew

 

[zcacogp]

Ah!

>MetallicClinkingNoiseAsThePennyDrops<

Thanks Andrew! []


Oli.

 

[DavidL]

ORIGINAL: zcacogp
I thought that the performance of the 968's were (broadly) on a par with that of the S2, and hence would expect a turbo to be quicker, and a modified turbo to be quicker still.
Oli.

Quick print it and frame it and wave it under his nose every time.....

 

[Diver944]

ORIGINAL: zcacogp

it sounds as if the first project is the one that is complete and operational; is this the one that people on here and PH (Paul Smith, Ben Burt etc) have driven, with the very enthusiastic reviews?

Yup, that's the one [8D]

It has standard wastegate, boost and chips but had a rolling road remap to make sure the fuelling was correct

 

[DivineE]

ORIGINAL: zcacogp

From that which you write, it sounds as if the first project is the one that is complete and operational; is this the one that people on here and PH (Paul Smith, Ben Burt etc) have driven, with the very enthusiastic reviews? If so, it sounds like the only modified (or not-off-the-shelf) parts required are the 968 pistons, with a larger dish machined out to lower the CR. Does it also run different chips/wastegate/boost control? (Here I am unsure of the details, but they are the parts the turbo boys seem to change to improve performance).

Yes the one we went in was made from all standard parts including standard 2.5 turbo wastegate, boost control and even boost pressure. Only the pistons were altered (still standard parts just machined to lower compression) and then it was set up on a rolling road (equivalent to adding a chip) to suit the 3.0 which requires different fuelling etc.

On another topic.. during my reading of turbo design books I keep coming across various methods and designs for creating an anti-lag system which works in basically the same way as a jet engine.

Apparently although this used to rather shorten the life of old turbochargers which melted over 900*C. A good modern turbo can run these systems quite reliably due to the recent developments in the materials used in turbo design, allowing them to survive closer to 1100*C. Anti-lag systems which inject a mixture of fuel and intake charge into the exhaust just before the hot side of the turbo, causing it to ignite with the heat of the impeller and whiz the turbo up to near 2 bar boost when the driver has let off the throttle (removing any lag) only creates temperatures of about 980*C.

All this got me thinking that I should have a go at making one (as simply as possible) on my car for a bit of fun. So my idea is to adapt the DV valve to feed into the exhaust when it dumps rather than back into the intake, then have a single injector in that pipe /or exhaust which is operated by some basic electrical system totally separate from the ecu and designed to send a short pulse to the injector when the vacuum system changed pressure (i.e. exactly the same as the DV valve).

Since the DV is already designed to help prevent turbo stall in a sharp throttle lift off situations it should operate at all the right times and an override switch inside the car could be used to disable the signal to the injector so it only operates when you know your going to need it and not when your just pootling around.

I've tried to think it through to make sure I'm not missing anything obvious and besides the jump in boost created when the fuel ignites not being accounted for by the ecu... I couldn't think why it wouldn't work. I hope that the initial boost spike will blow its way straight back through the DV valve and into the exhaust until the throttle is re-opened in the next gear so hopefully avoiding any upset to the ecu and instead giving lag free delivery as you come on and off the throttle sharply.

However I'm no Engineer so has anyone more technical tried this or seen anything glaringly obvious wrong with my idea? If not I'm going to have a go and see where it takes me when I fit the new turbo.

Whats the worst that can happen[]

 

[MRGT]

ORIGINAL: bazhart



A 944 S head could be fitted to the std 2.5 turbo block if anyone wanted a 16 valve version.

Any chance you could do this in reverse ie fit a turbo to the 944 S ! []

 

[DavidL]

ORIGINAL: MRGT

ORIGINAL: bazhart



A 944 S head could be fitted to the std 2.5 turbo block if anyone wanted a 16 valve version.

Any chance you could do this in reverse ie fit a turbo to the 944 S ! []

Yep, its called a 968 turbo and that'll be 25K please.




Not entirely accurate but it is a 16v turbo

 

[zcacogp]

ORIGINAL: DavidL

ORIGINAL: zcacogp
I thought that the performance of the 968's were (broadly) on a par with that of the S2, and hence would expect a turbo to be quicker, and a modified turbo to be quicker still.

Quick print it and frame it and wave it under his nose every time.....

Some absolute bounder nicked my login details. []

Must inform the mods. Perhaps one of the Pauls could do something about it ... []


Oli.

ETA: Thanks for the helpful answers. To the questions that the aforementioned bounder so kindly asked on my behalf ...

 

[sawood12]

ORIGINAL: DivineE

ORIGINAL: zcacogp

From that which you write, it sounds as if the first project is the one that is complete and operational; is this the one that people on here and PH (Paul Smith, Ben Burt etc) have driven, with the very enthusiastic reviews? If so, it sounds like the only modified (or not-off-the-shelf) parts required are the 968 pistons, with a larger dish machined out to lower the CR. Does it also run different chips/wastegate/boost control? (Here I am unsure of the details, but they are the parts the turbo boys seem to change to improve performance).

Yes the one we went in was made from all standard parts including standard 2.5 turbo wastegate, boost control and even boost pressure. Only the pistons were altered (still standard parts just machined to lower compression) and then it was set up on a rolling road (equivalent to adding a chip) to suit the 3.0 which requires different fuelling etc.

On another topic.. during my reading of turbo design books I keep coming across various methods and designs for creating an anti-lag system which works in basically the same way as a jet engine.

Apparently although this used to rather shorten the life of old turbochargers which melted over 900*C. A good modern turbo can run these systems quite reliably due to the recent developments in the materials used in turbo design, allowing them to survive closer to 1100*C. Anti-lag systems which inject a mixture of fuel and intake charge into the exhaust just before the hot side of the turbo, causing it to ignite with the heat of the impeller and whiz the turbo up to near 2 bar boost when the driver has let off the throttle (removing any lag) only creates temperatures of about 980*C.

All this got me thinking that I should have a go at making one (as simply as possible) on my car for a bit of fun. So my idea is to adapt the DV valve to feed into the exhaust when it dumps rather than back into the intake, then have a single injector in that pipe /or exhaust which is operated by some basic electrical system totally separate from the ecu and designed to send a short pulse to the injector when the vacuum system changed pressure (i.e. exactly the same as the DV valve).

Since the DV is already designed to help prevent turbo stall in a sharp throttle lift off situations it should operate at all the right times and an override switch inside the car could be used to disable the signal to the injector so it only operates when you know your going to need it and not when your just pootling around.

I've tried to think it through to make sure I'm not missing anything obvious and besides the jump in boost created when the fuel ignites not being accounted for by the ecu... I couldn't think why it wouldn't work. I hope that the initial boost spike will blow its way straight back through the DV valve and into the exhaust until the throttle is re-opened in the next gear so hopefully avoiding any upset to the ecu and instead giving lag free delivery as you come on and off the throttle sharply.

However I'm no Engineer so has anyone more technical tried this or seen anything glaringly obvious wrong with my idea? If not I'm going to have a go and see where it takes me when I fit the new turbo.

Whats the worst that can happen[]

Temperature is going to be your problem. If it was that simple then all turbocharged cars would have these systems - they are nothing new or amazing, in fact diesel engines have used these systems for some times where the combustion temps are alot lower. The limiting factor is the cost of the materials to withstand the temps. 980 degs might sound 'cool', but steel alloys at that temp is very soft, plastic and loses strength and mechanical properties so are useless. Aero engine makers spend billions developing exotic materials to make turbine components from and keep their alloys and technology closely guarded secrets. The materials used in gas turbine engines that are operated to within a few degrees of their melting temps operating in environments about 50 degrees higher than their melting temps and utilise very fancy technology to create a very thin film of cooling air around the components, and the materials retain their mechanical properties right up to their melting temps.

Porsche are the only manufacturer that uses VGT turbos on petrol engines and the turbo's cost £6k each - the expensive bit being the materials the variable inlet vanes are made from to withstand the exhaust gas temps.

Also, i'd have thought that injecting fuel into the exhaust manifold would be a very dangerous. With the restriction of the turbo you'd be creating a pressure vessel and at risk of causing an explosion!

 

[zcacogp]

ORIGINAL: Diver944

It has standard wastegate, boost and chips but had a rolling road remap to make sure the fuelling was correct

Another Q.

Did it start life as a 220 or a 250bhp machine? (Although, a subsidiary Q would be 'how much difference would that make?' The main differences are the turbo and the chipset, non? And the chipset would be replaced by the output from the rolling road remap - please correct me if I am wrong.)


Oli.

 

[MRGT]

ORIGINAL: DavidL

ORIGINAL: MRGT

ORIGINAL: bazhart



A 944 S head could be fitted to the std 2.5 turbo block if anyone wanted a 16 valve version.

Any chance you could do this in reverse ie fit a turbo to the 944 S ! []

Yep, its called a 968 turbo and that'll be 25K please.




Not entirely accurate but it is a 16v turbo

Ah.
That may be a stumbling block.[&o]

 

[Backyard Racing]

Hi Ben

The anitlag setup your referring too will vastly reduce turbo life, even on new modern turbos imo, also you would need some wacky DV spring to withstand/hold back the exhaust mani pressure your going to create with the extra temps/energy, which will prob over come the inlet pressure so may never open fully anyway. I think with gear changes so fast the amount of air your trying to induce from the dv to turbine housing will be minimum. If lag is an issue then you dont have the correct balance of tune for what ever your purpose the car is being used/built for.. If lag from a standing start is a possable issue then on most standalone management systems you can set this up pretty easy in the ecu by ign retard and uping injection duty at a such selected rpm. This will create huge backfire thus generating spool. Once the car moves from the line the ecu will deactive this and switch back to normal map 4-6mph depends on set up, off course you need a speed sensor for all this work, ABS ring will work fine tho with a basic 2pin pick up..

Vnt turbos are good (been used on alot on other petrol tuned road cars for the past 5-6years as an aftermarket unit) but the only off puting thing for me is the massive torque spike at low rpm, this can easily course det and huge cyclinder pressure and with poor mapping total fail.. If i ran a vnt id map the TPS with a boost controler (stop fast spool at part throttle) along with rpm.

The most cheapest/effective vs £££ way to reduce lag is Nitrous..

Rob.

 

[Mike_Pollock]

Hi Scott
Injecting fuel into the exhaust is a well proven idea to reduce turbo lag.
Mike

 

[944 man]

A Mitsubishi TD05 turbo will last for about 2,000 miles with proper anti-lag. Most, if not all anti-lag on road cars, is really 'anti-lag' ie. pops and bangs mapped in.

If you want to improve the 951s behaviour, then youd be better off by replacing the agricultural turbocharger with something a little less nineteen seventies!