Wortec versus Fabspeed...

[Indi9xx]

We have two cars with us at the moment with a very similar spec, which is not the traditional path of improvements, both are fitted with (what should be) a free flowing exhaust, MAF kit, larger injectors, improved intercooler, DPW, EBC etc etc.. But with a stock turbo.. The idea being to create a very torque biased car with minimal lag.

The interesting thing is that both cars are making 1.0 to 1.2 bar of boost by 2800 rpm and holding it until the redline, although towards the red line both cars are at their limit with the standard k26/8.. However, we have noticed something really interesting, and would be interested in some input from some of you guys. In particular, any of you with experience of a Wortec exhaust...

One car has a Fabspeed 3.0 inch exhaust from the tailpipe to the turbo... the other has a Wortech, and although the Fabspeed car gets maximum boost noticeably sooner, we compared the maps we have custom made for both cars, and found that to avoid the onset of detonation on the car with the wortec, we have had to use considerably lower air fuel ratios.

We have seen cars with Wortec exhausts in the workshop numerous times, and although I have never been a fan of them, I was not expecting to find such a difference in the fueling used on the Wortec car compared with the Fabspeed.

As mentioned before in other threads, I am not a stockist of Fabspeed or Wortec, but do confess I am a fan of the Fabspeed exhaust systems from my experiences of tuning cars with them, but would be interested in being directed to anyone's dyno charts from cars with a Wortec and a decent mapping, so I can analyze the AFR plot on the chart.

I would have suspected a bad set of injectors or a fuel pressure issue, however my curiosity has been sparked due to the AFR we have had to tune to, not the duty cycle for the injectors we have mapped..

Other than that, both cars are running the same spec and the Wortec engine seems to be as fit as a fiddle.

 

[T3rra]

Could there be a differnt rate off oil blow by between the 2 cars creating a less oct rating off fuel. Could one intercooler be in better health then the other? Or even engine temps

I'm guessing you have filled both cars up at the same time from same pump.

2800 is good for 26/8 based on my Apexi I'm also seeing 1bar around 2.8k in 5th with full boost of 1.3 by 3k
4th 3k 1bar and full boost by 3.2k on stock exhulst with simmler mods.

 

[aporschefan]

I think I have an old pdf with a dyno reading somewhere. I'll have a search for it this weekend and upload it if I find it.

There may not be much info available though about the car which the reading came from apart from the fact that it had the Promax L2 kit.

 

[aporschefan]

Not having much luck uploading the file Jon. I'll email it to you shortly.

Not sure how useful it will be though as we don't know much about the base car other than it has the L2 ProMax kit.

The graph shows with the L2 kit and without the exhaust the car has:

Torque: 272 @ 3238 rpm.
BHP: 257 @ 5493 at rpm

And with the L2 kit and the Wortec Exhaust:

Torque: 285lbs @ 4237 rpm.
BHP: 268 @ 5487 rpm.

Note: these readings are not from my car but from a graph I found online some time ago.

 

[Indi9xx]

I think I know the issue, I just wanted to double check to see if other people who have had a 944 turbo with higher than standard exhaust flow requirements had experienced high EGT's or excessive back pressure, which might increase the cars fuel requirement to avoid the onset of detonation.

Nothing to worry about Jabriel, I suspect that our overly sensitive detonation detection methods is a little too sensitive for your car until that engine has done some actual work.

[]

 

[T3rra]

Would fabspeed be a better exhulst over wortec then?

Is there anything noticeable differnt between the two that could cause this? Iv still got to go 3" yet. Are the both 3" following the same route as stock and made from the same grade off metal with same thickness which mit effect heat displacement ?

 

[MarkK]

I thought the Wortec production run was over?The fabspeed quality is epic,I ran one on my ex turbo race car,got the 4 inch on my red car.Have a look on their website for an idea of the quality of construction and finish-pretty stunning.They arrive very quick too,easy to deal with.

 

[Indi9xx]

Not sure how long this Wortec has been on the car and it is the first time someone has wanted a reasonable level of tune and use the Wortec... Pretty sure the fuel we have had to dial in compared with the sister car wearing a fabspeed is down to a more restrictive turbo outlet and downpipe than the fabspeed.

Maybe a fabspeed should be on the owners shopping list for 2014

 

[George Elliott]

Jon, I imagine if the Down-pipe is not upgraded there is minimal benefit from the bigger exhaust?
George
944t

 

[Indi9xx]

Well, we can look at the downpipe as two parts, the turbo discharge and the downpipe to what would normally lead to the cat or front silencer.

As standard, the k26/8 turbo does not have a 3 inch outlet on the turbo hot side, but the housing can be machined to blend out to 2.75 to 3 inches, which then means you get some gains from something like the Fabspeed 3 inch discharge, which cheekily is actually about 2.8 inch... If matched together with a locating dowel and some blending is done, along with the hot side housing machining tapering out to this size, then there are some real benefits to be had both in flow and the gas law/thermodynamic improvements to the turbo discharge.

However, bolt a fabspeed discharge onto a standard k26/8 without this mod to the hot side housing, and the step you will be left with will cause some nastly turbulance to the gas flow, which will then actually reduce the area of the outlet seen by the gas flow.

the fabspeed discharge is a true 3 inch outlet at the other end, which mates nicely to the rest of a 3 inch fabspeed system... Which overall, is a good thing, even for a little k26/8, but essential for any bigger spec turbos.

The wortec seems to use a standard 944 turbo discharge, which is already a good match for the k26/8, and then has a splitter and continues as a twin down pipe until just before where the cat would start, at which point it combines back into a single tube. Not sure why they have done this, other than perhaps they have trouble with forming bends in larger pipes other than small angle ones..

I think there might be an argument for Wortec's double tube downpipe, it could be on the basis of reducing the difference in lengths of the short and long sides of each bend, as the downpipe turns to go under the car, being closer together, which could in theory help flow.. But that would almost certainly be counteracted by the turbulence caused by a 1 into 2 splitter and then a 2 into one collector a short while later.. If this is what they were aiming for, perhaps the use of oval formed tube of the right cross sectional area would have been a better option.

I suspect it was more to do with manufacturing issues.

I was once in discussion with a company who specialise in oval stainless tubing and oval tube bending about doing something similar, which could have had some gains, but to be honest no one is pushing the envelope enough with 944 turbo tuning to make those gains and the cost overhead worthwhile. The extra money is probably better directed by that stage in the game of changing the camshaft for something less conservative, but no one ever seems to even do that.

 

[TTM]

ORIGINAL: Indi9xx
However, bolt a fabspeed discharge onto a standard k26/8 without this mod to the hot side housing, and the step you will be left with will cause some nastly turbulance to the gas flow, which will then actually reduce the area of the outlet seen by the gas flow.

the fabspeed discharge is a true 3 inch outlet at the other end, which mates nicely to the rest of a 3 inch fabspeed system... Which overall, is a good thing, even for a little k26/8, but essential for any bigger spec turbos.

Is it me or you are saying that a nasty turbulence is a good thing?

For what it's worth I noticed a dramatic improvement when I replaced the standard exhaust with a full 3" exhaust using one of Simon's Garrett/KKK hybrids turbo, so I would say that the turbulence caused by the step between the outlet and the discharge pipe may not be that much of a problem, and that was with a 3.0 engine, meaning probably more backpressure than with a K26/8 on a 2.5 engine.

 

[Diver944]

Sounds to me like you are saying the Wortec car has a standard turbo discharge pipe and the Fabspeed car has a full 3 inch discharge pipe. If that is the case, then surely it explains the difference in one fell swoop? [&:]

 

[T3rra]

Quite right
All thou from tbe 1st post, "Both cars are 3" From turbo back." I believed Both down pipes where larger then stock and larger then the hotside exit.

 

[George Elliott]

Sounds to me like you are saying the Wortec car has a standard turbo discharge pipe and the Fabspeed car has a full 3 inch discharge pipe. If that is the case, then surely it explains the difference in one fell swoop?

Jon, this must be the cause as Paul questions, its apples and Oranges...? I am surprised the Wortec is even vaguely similar. But that in its self makes interesting reading.

TTM, I think Jon is saying the step at the outlet / possibility of turbulence is not desirable. Running a similar hybrid Garrett/KKK ball bearing unit, my Down Pipe has a 12 deg taper for about 20mm at the Hotside outlet, leading to the full 3" bore which is maintained to the rear bumper. This taper was provided to avoid the step. Unfortunately I am only shipping 2479cc through the system[]

Just returned from a 200 mile trip, and noticed my boost build up, - at 1900rpm under load my car shows 0.3 Bar. I think [8|] a turbulent free flow of air at low rpm would assist this....?

....and a better Cam would further assist, .......and a better ECU.....and Spark...[8D]

George
944t

 

[T3rra]

I got 3" turbo down pipe awhile ago and did some resreach to see if it was worth fitting yet. With the stock turbo in stock form there wasn't any claims made. Not even by fabspeed them selfs. Iv read off stock item been double walled and the inside collapsing over time. Which would cause a huge restriction

The results off what I could gather was unless your stock down pipe has collapsed or your turbo outlet was larger then stock the down pipe wouldn't provide any gains. Some down pipes even bottle neck back to stock side then increase after the mounting pointing on the next part off the system.

Could it be that no one has done any testing, I haven't. But it was intersting that fabspeed them selfs joined in a few threads and made no claims of an upgrade unless the above.

 

[T3rra]

Went and took a tape to my 3" fab speed turbo down pipe it's more like 2.6"

Now this was only done with a tape, but should be pretty close.
OD off 70mm
ID off 66mm

Not sure what stock pipe is
But on my stock back box tube is 65mm OD
Not sure ID but I would think 60mm

So a possable difference off 5mm which is also how much smaller the 3" the fabspeed item really is so instead off it been half inch upgrade its only 5/6mm instead off 12.5mm

Fabspeed list it as 70mm on there site so there's no misleading on there part.

 

[George Elliott]

full 3" bore which is maintained to the rear bumper

Sorry, just to correct the above, its 3" OD with 1.5mm wall stainless, so 76.2mm OD and 73.2mm ID