turbo mods

[barks944]

Ive been thinking that i might got down the small ceramic bb turbo turbo route and getting spoolup as quickly as possible with the aim of producing massive torque at the low/mid rpm range and forgetting about high rpms. This way you would get a fast car without worrying about making the engine flow at high rpm. I think this would make best use of the charachter of an 8v engine which isn't suited to high flow rates at big rpm. Why go against the flow? Maybe boost by 2k and a 5krpm rev limit or something.

 

[TTM]

ORIGINAL: barks944

Ive been thinking that i might got down the small ceramic bb turbo turbo route and getting spoolup as quickly as possible with the aim of producing massive torque at the low/mid rpm range and forgetting about high rpms. This way you would get a fast car without worrying about making the engine flow at high rpm. I think this would make best use of the charachter of an 8v engine which isn't suited to high flow rates at big rpm. Why go against the flow? Maybe boost by 2k and a 5krpm rev limit or something.

The turbo is I think the part that will have the greatest influence on how an engine will feel from the driver's seat and yes, a bb turbo will be perform better than a non-bb turbo. I would avoid a turbo that is "too small" though, a GT30-based bb turbo should be responsive enough on a 2.5.

 

[DivineE]

ORIGINAL: barks944

Ive been thinking that i might got down the small ceramic bb turbo turbo route and getting spoolup as quickly as possible with the aim of producing massive torque at the low/mid rpm range and forgetting about high rpms. This way you would get a fast car without worrying about making the engine flow at high rpm. I think this would make best use of the charachter of an 8v engine which isn't suited to high flow rates at big rpm. Why go against the flow? Maybe boost by 2k and a 5krpm rev limit or something.

Totally agree but two points worth noting. First my friends skyline spat its ceramic turbo's down the exhaust when he raised the boost because they are not as tough as steel impellers so be careful and second I went out in a very well built car with exactly this set up built by RPM and whilst it would have undoubtedly be extremely hard to catch round a track the total loss of lag due to tiny modern turbo did lose a little of the cars character. It felt more like a modern hot hatch, which I'm sure some will consider high priase but I like the old bang and wallop, head sucked into the headrest feeling.

 

[poprock]

ORIGINAL: DivineE

"¦ I like the old bang and wallop, head sucked into the headrest feeling.

Here, here. That is exactly what I love about the 944 Turbo. I went for a passenger ride in my car before buying it and the first time I felt that moment of push was when the stupid grin spread across my face and I got my chequebook out.

There's no way I would intentionally smooth that lump of boost out of the power curve. It's the whole point of the car for me. Without it I could have just bought an S2 instead.

 

[Suffolk944]

Exactly, the "old style" boost is a major part of the character of the car and always puts a grin on my face. I have lost some of that on-off power delivery with the mods but its still there and I certainly would not want to lose it altogether !

 

[zcacogp]

ORIGINAL: poprock
Without it I could have just bought an S2 instead.

Really? []


Oli.

 

[barks944]

You wouldn't necessarily loose that, just shift it down the curve. You will still have the progression from off to on boost....

 

[DavidL]

The main reason for me asking this is that RPM have a LR 340 kit available.
I have decided not to go for it but if anyone else would like to consider it then it is available for 1500. Fitting by Promax (who deal with LR anyway) would be around 25-30 hours so around 1750. They are happy to do so for this particular kit.
Bear in mind the kit direct from the states is $4000 so around £3400 with duty etc so it is a good deal.
In the end I just couldn't justify the rest over a good S2 kit but I may be missing a trick.

Hope someone is braver than me.

 

[DivineE]

ORIGINAL: barks944

You wouldn't necessarily loose that, just shift it down the curve. You will still have the progression from off to on boost....

If anyone on here owns it I would recommend you go for a spin in the black RPM turbo that was recently sold before you make your choice. Even Simon P's Red turbo was heading that way. I think you need exactly as TTM suggests something about GT30 size with a 76mm A/R and .86 hotside to keep the 944's character with a BB turbo. That way you get a little more turbo assist everywhere than standard (which I like because it means a lighter throttle at slow speeds) but still get a big exponential surge of power from just over 3000rpm up which reminds you your in an 80's turbo[] ...only trouble is Simon SPS tells me fitment of that turbo is pure hell and he would know as he tried this on his first car. The most sensible solution is to buy one converted to use the KKK hotside... which is £1500 or more.. but then you need the injectors, 3inch downpipe to make use of it, full exhaust, probably a maf etc etc there's no cheap easy solution [&o]

I'm almost totally certain I'm going to put my BIG intercooler on a standard turbo and wind the boost up to 1.2 bar so I'll stick it on a dyno and report what effect that has in a couple of months.

 

[barks944]

Will be interested to hear how you get on with your intercooler. I had a local Landrover tuning and fabrication company near me weld a new end tank onto my IC and it made the spool up noticebly quicker. When I take the snorkel off the air intake car spools up very nicely indeed.

I think the first step in all this is the engine management system. Ive been looking harder into creating a replacement digital board for the 944's DME. I think I understand the circuitry now and the only issue I have at the moment is with the reference sensor circuitry. It uses a special timer chip to generate a binary signal from the saw tooth signal produced by the flywheel sensor. Its not an especially complex problem but it will take me a little while to come up with a solution. I hope to make use of all existing wiring simlpy replacing the AFM with a 4 pin 5v MAP sensor. I have also found a clever chinese chap who can help me write all the code!

 

[DivineE]

Wow I would be extremely interested to hear your progress with that. I think I'm giving up on going the stand alone route. Good as it is there is a lot of time and expense in ripping out the loom and I just don't have the energy to to such a big project. There is so much else to do on my car right now modifying has just got to sit on the back burner except the inter cooler which I've come up with a good plan for. I'm going to cut 200mm off the core and weld the end tank back on so it fits straight into the car with only a bracket needing fabrication. I wasn't really comfortable with cutting the front of the car apart to fit it and I don't need an inter cooler any bigger than will fit in the space. It will still be about 3 times the size and should flow many times better than the standard unit when complete.

 

[barks944]

Sounds like a good plan. Like you say getting everything into top condition before starting with upgrades is a good idea.

With regards to the new DME board, I have been looking at how feasible it would be to do such a thing and I'm pretty convinced I can do it now. It would retain the standard knock protection offered by the KLR. Also boost control could be added easily and installation should be about as easy as changing a chip plus the installation of the MAP sensor. Tuning/datalogging would be done over USB. The only issue with using MAP would be tuning, a MAF sensor doesn't really require tuning as its measuring air flow. MAP does not really tell you anything about how a particular engine is flowing so would need to be mapped to the car. However I think the kit could be produced cheap enough such that even with dyno time it would work out cheaper than what is currently available. It would offer the benefits of a more 'neat' solution without the need for a piggyback.

I have copies of the 944's DME code and I have an app which can read all the maps. This would allow the base maps to be copied over from the factory DME. This should help for things like cold starting.

 

[DivineE]

Top work! Sounds fantastic and I would love to see a UK based product on the market. If you do manage to put something together maybe one of the existing UK tuning companies would be interested in partnering up with your product (similarly to the way Jon Mitchell works with Simon on the SPS turbos).

The ability to run a map sensor and make your own adjustments via USB just by plugging a new ECU unit into the existing system would be a level of product not yet seen on the German tuning market. 'Mines' offer something similar for the Jap market and I've always been jealous. If it works you should consider building one for the 1.8t VAG engines because there are thousands of these and the standard ECU is awful! All the tuners have problems with them.

 

[barks944]

Hmm, interesting idea there!

Another idea I have been toying with i using a air water heat exchanger mounted in the location of the existing intercooler and placing the radiator in front of the engine coolant radiatior. Its a great way of getting IAT down without any significant pressure drop, but at the expense ofa slight increase in complexity.

 

[DivineE]

ORIGINAL: barks944

Hmm, interesting idea there!

Another idea I have been toying with i using a air water heat exchanger mounted in the location of the existing intercooler and placing the radiator in front of the engine coolant radiatior. Its a great way of getting IAT down without any significant pressure drop, but at the expense ofa slight increase in complexity.

It's a personal opinion based on no fact of study what so ever but I've always felt the weight of a charge cooler, separate tank, pump, hosing and the extra volume of water would outweigh any minute benefit you might get over a decent air to air inter cooler in this country. In a desert maybe but I still think the water would soon reach air temp.

 

[DivineE]

Fitting a front mounted inter cooler low down so you allow the original intake slot for the inter cooler to become a cold air intake for the engine then removing the air box and relocating in place of the old inter cooler with nitrous spray jets on the new inter cooler pointing upwards so you freeze the inter cooler and allow a mist of nitrous to enter the intake at the same time... now that is an idea.

Quite crazy but I've looked at it and there is a nice big oval under the metalwork you could fit an air intake pipe through. An idea for the future maybe.