K27 on a 951 - comments welcome

[George Elliott]

Anyone got experience of a K27 turbo on a 951?
The objective would be good drivability, complete reliability and with more power.
Is it bolt on and can it be watercooled?
What other mods compliment it?
Comments and experience would be welcome.
George

'89 944T

 

[944Turbo]

I have a K27 hybrid on my car, K27 coldside with 250 number 8 hotside and centre - even that doeant bolt straight up, it wont clear the brackets on the inlet manifold and it needs an adaptor for the coolant line and the intake pipe. driveability is ok with a MAF electronic boost controller and a larger exhaust and was reasonable on a mostly standard car.
Mine was a rebuild/mod to the standard turbo so had the watercooled centre etc. A 911 K27 turbo would be oil cooled only.
Tony

 

[sawood12]

Tony, has yours got balls too?

The impression I've got from reading Rennlist threads is that the K27/8 (non ball bearinged) is a bit slower to spool up than the std K26/8 but on balance is better and gets good reviews.

 

[944Turbo]

360 thrust, Its ok but if I was doing it again I would be speaking to Simon at SPS,
Tony

 

[DivineE]

I'm suprised thats your impression of your car. I felt that for the fairly modest modifications you have your car well out performed other modified 944 turbo's on a cost / result basis (was pretty rapid by any standards anyway!) plus it seemed to spool exactly like my standard 250 anyway. Didn't feel any more laggy just a lot quicker on boost!

Ben

 

[George Elliott]

Tony, thanks for your comments
You would know as you run the set-up, but my impression was like Scott and Ben, - a K27 is/was[8|] regarded as a generally good combination.
You also mention/rate SPS - do they build K27's, who are they?
Do I detect you're being modest about a fairly straight-forward package which performs 30% up on standard and remains reliable? - which is exactly what I am aiming for.

George

'89 944T

 

[sawood12]

Simon at SPS basically built Paul's turbo which is packing alot of the latest turbo technology (i'm sure Paul will be along soon with more details!). I think the basic K27/8 is a bit dated now as turbo technology has really come on. There are some clever bearing technology to aid spool up, fancy multi-vane technology that again aids spool up and even variable vane technology coming on-line, though i'm sure it wont be cheap as the enabling technology for petrol engine variable vane turbo's are the high-temp materials used which generally don't come cheap. Simon at SPS can build you a bespoke turbo to your specs/requirements.

 

[AndrewS]

Hi George,

A K27 is very much like an LR Super 61 (in compressor size), only the LR Super can be water cooled and requires no mods to make it fit.

Regards,
Andrew

 

[Indi9xx]

SPS is a business owned by Porsche enthusiast Simon Peckham, who build the very best of Porsche engines, cylinder heads, transmissions and turbos to specific requirements (from stock to completely wild).... SPS build turbo's designed using the latest technology and genuine parts from Garrett and KKK. We use SPS exclusively for turbo, transmission and engine supply.. and can not recommend them enough!

Saying "K27" is a very broard term, but also relates to 1980's technology manufactured by KKK.

TurboNetics are a company who make low price alternatives (clones) to genuine KKK parts, which are used in many American made turbo's... You really need to check what parts are included in a TurboNetics turbo, as some of their cheaper hot sides have a very low nickel content which can make them prone to cracking... also TurboNetic's turbos are often sold as ball bearing, when they are really not a complete ball bearing shaft assembly, but instead are a single bearing just so they can call them a bearing turbo... also their idea of a 360 degree thrust bearing isnt really the real deal.... Buyer beware.

LindseyRacing are an American company who make the LR series turbo's that Promax sell and that we used to use prior to SPS.

I would recommend calling SPS who I am sure would offer some free advice on the pro's and cons of various turbos.

 

[Neil Haughey]

ORIGINAL: Indi9xx

Saying "K27" is a very broard term, but also relates to 1980's technology manufactured by KKK.

I guess it is a product family then.

 

[DivineE]

I didn't realise K27 related to more than one turbo, I was going to say... the Lindsey Lr Super 61 I bought from Promax (and then sold without fitting) was nothing like the KKK model K27 I was thinking of?!

Ben

 

[George Elliott]

You are all assisting me greatly, while also highlighting how much I have to learn about this subject, but it is of enormous interest me.
I have 2 944T's, one is a '89 which I drive, and the other an '88 250 w/o sunroof - no mods. Red / blk logo (with silent transmission - honest) 140k miles, never smashed.
I have some minor mods, supplied by Promax which make the '89 car very enjoyable to drive. DPW,SciVis, DV30, FPR, 1.2bar Chips. Cometic Gasket.
I suppose the '88 is a project car, which I intend to refresh, and while maintaining stealth appearance, I want to give it a few more horses. In achieving this, I want to ensure the car will remain totally reliable and relatively economical. A bit of lag is OK and to be expected with 951 layout / pipework.
The K27 question arose largely because I am conscious that poorly chosen mods can make a car worse.
My vague plan is around air-flow - its what Porsche restricted when the car was made, and I intend to reverse that. The turbo unit is central to my plan.
A KKK unit is durable and being watercooled is essential IMO. A K27 also comes to mind because Porsche used one on the 968TurboS - 3litre I know. (which K27 i'm not sure). I also think K27 because high rpm airflow/cfm on a K26 is poor.
I intend to stick with 2.5litre, they are "nice" - a bit revvy, - only if my engine block is poor would that be negotiable. Plus I like "matching numbers" - sad 'eh[8|]
Andrew at Promax has achieved genuine 400+ with a 2.5, which is more than enough for me, 350 @ 17psi would keep me happy. A LR61 sounds like its sized for that application and its watercooled, but being at the "research stage", I will first look into the K27.
At least I may finally understand the K27 family you mention Neil.
Thanks all.

George

944T

 

[Diver944]

ORIGINAL: George Elliott

A bit of lag is OK and to be expected with 951 layout / pipework.

Not neccesarily [] I think the right sized KKK hybrid from Simon at SPS with a ballrace bearing would really surprise you even with a 2.5. Yes they are expensive but you do get what you pay for.

A target of 350bhp at only 17psi will be very difficult unless you really spend some cash on the intake and exhaust to get enough flow through the engine. If you look at all the charts on Ricks site you'll see that the few who have achieved more than this figure are in the 20psi range.

If you can't go for a ballrace turbo then I would recommend researching one of the Vitesse Racing kits with turbocharger and MAF kit included. You don't need to go for the full piggyback 'semi standalone' system as his included chipsets are near perfectly matched when he supplies the full package. With the dollar at 2 for 1 just now it will be very good value

 

[MarkK]

LR super 75 works for me![][]

 

[944Turbo]

ORIGINAL: George Elliott

Tony, thanks for your comments
You would know as you run the set-up, but my impression was like Scott and Ben, - a K27 is/was[8|] regarded as a generally good combination.
You also mention/rate SPS - do they build K27's, who are they?
Do I detect you're being modest about a fairly straight-forward package which performs 30% up on standard and remains reliable? - which is exactly what I am aiming for.

George

'89 944T

Sorry for the delay lots of work on at the moment,

There is no doubting mine works (only one in the league table I think) - recently fiited a new intercooler which seems to have helped it further.
However a Turbo is a lot of work to fit and technology moves on - Simon at SPS has a lot of turbo experience and in the past has built model aircraft jet turbines - he has been working with 944 turbochargers for a few years now, initially on his own car. Look at Ricks site and see how fast they spool compared to the lindsey offerings. Area under the curve equals performance. So yes a hybrid based on the K27 can be an economical choice but better is available (Simon could build a K27 hybrid - assuming the hotside is in good condition - many are not mine was but was done by ITS in Bradford before Simon had moved onto 944's) If you are going to the trouble of fiiting one you probably only want to do it once.
Tony

PS I was told mine would be a direct bolt on and it wasn't - ITS gave me a partial refund but I was without the car for longer than I hoped.

 

[George Elliott]

Tony thanks
I will look on Ricks site, not seen the plots before
bit hectic here too
George

 

[333pg333]

I really find that phrase 'area under the curve' quite strange. To me the nature of the complete engine and therefore the dyno graph to represent it, shows the tq and power curve at any given rpm. So if you're getting 350hp at 5500rpm with a similar tq value, then it's not the area directly underneath this that interests me, it's the details of what has preceeded it to get me to that point. In other words what was the tq/hp at 5000, 4500,4000,3500,3000 etc...If I slap on a great big GT35 on an engine that doesn't have many more mod's, and pump the boost up to 24psi then I may just get 350hp at 5500rpm but it wouldn't be a usable power band. Conversly if I made a bunch of mods to this car to enable it to breathe better and I was able to get the same 350 at 5500 rpm but at 18 psi then the power band would have much more tractability. I really don't know why I'm looking at the 'area under the curve'. I think this phrase sounds like someone is trying to sell me something.
By the way and back onto topic, I can attest to the Vitesse products. They do bolt on, they do work, and while they're expensive to import to Australia I agree with Paul that with your Pound they could present a good easy alternative. Would an SPS turbo be a better product, by the sounds of it yes but how much are they and do they come with the chips as well?

 

[sawood12]

There is a school of thought that when it comes to turbos bigger is not always better. With larger turbo's delivering large chunks of power and torque in large lumps you physically can't get it onto the tarmac. I have managed to spin my wheels before with my relative lowly BHP levels purely through the boost kicking in. Imagine having a huge turbo that gives you 350bhp in one large lump - LSD or no LSD you're wheels are gong to spin and you are going nowhere fast. Having a smaller turbo that spools up more quickly with a wider power band (i.e. more area under the curve) with lower peak power gives you more USABLE power. It's not how much power you have that is important - it's how much power you can use. On track this gives you the advantage of getting on the power out of a bend earlier.

I've wondered what an SPS built equivalent of a K26/6 or a K26/8 would be like. With ball bearings it'd spool up so quickly turbo lag would be a thing of the past, and because the turbo would spin much more freely it would hold boost pressure higher up the rev range, especially with the compressor utilising more modern compressor vane profiles meaning the compressor can work efficiently over a wider rev range. It would drive like an N/A car and be good for over 300bhp. Can't be too shabby.

Just as an aside I have read that one of the downsides of the LR Super 61 (and probably the only) is that there is alot of clearance between the tips of the compressor vanes and the casing. Ideally this clearance wants to be as small as possible but for some reason on the LR61 it isn't. This effects the compressors efficiency at high boost pressures. I don't fully understand the implications of this in real terms but I can't help thinking that it's not ideal and that things would be a bit better if these clearances were smaller. Maybe someone with a bit more knowledge on the subject can comment on this.

 

[333pg333]

No, Scott I wasn't implying or suggesting getting by getting a larger turbo will be better than something more suited. I was saying that again when you used the phrase A.U.T.C. that it wasn't under the curve that was important it was the curve itself. I think you are saying the same thing as me but I really find this phrase misleading. It suggests that if we looked at the same dyno as my hypothetical GT35 one before and saw that there was nothing, nothing, nothing, then bang for 1000rpm--change gear etc rather than something more suited that gave us a broader power delivery, that at any given rpm we can drop down immediatly underneath on a vertical axis to this supposed AUTC and we are looking at what preceeded it. What I'm saying is (and rather badly I confess) that the 'meat' is not on a vertical axis but on the curve itself that has preceeded wherever it is we are at then and there. This is really hard without being able to draw. I think I mean that at any given point on the curve I have only that amount of power not the sum total of the power that got me to that point...err if you see what I mean.
Oh and if you have KW's you will be able to apply more of that power to the ground without leaving rubber all over the track and going nowhere. lol
I always thought that by having smaller vanes was to assist in spoolup, but sacrificed top end power.

 

[DivineE]

ORIGINAL: 333pg333

as my hypothetical GT35 one before and saw that there was nothing, nothing, nothing, then bang for 1000rpm--change gear etc rather than something more suited that gave us a broader power delivery, that at any given rpm we can drop down immediatly underneath on a vertical axis to this supposed AUTC and we are looking at what preceeded it.

I don't mean to offend but I think your missing the idea behind the phrase. Your argument is actually in line with the theory of creating a larger area under the curve.

What they mean is you cant just look at the peak bhp figures and think a car will be fast, actual speed comes from having a larger square area under your torque curve. i.e. power through the rev range not just one peak at the end.

Regards,

Ben