Porsche Enthusiasts Club Forum

Looks like a great project and some nice fabricating

Looking forward to seeing how this pans out!

Update 5

I have finally reached the stage where parts are going on for the last time.

Here is a few pictures of the replacement AOS can that will give the DP more room as well as not having problems with standing heat.






This took a great deal of time to get right but looks the business now. I intend to get it Zircotec coated when I do some other bits on the car.

I have also finished my X-over and am pleased with how it has turned out. I have heat wrapped it along with the rest of the under bonnet exhaust components.




This is a general under bonnet image from a few days ago, things are starting to take shape.



I have all the metal work etc complete now so I've taken everything off and am cleaning as I reinstall for the last time.
This should mean the car will be running very soon and I can't wait!!!

O wow deaf be interested in getting some bits from you. Is that aos working better then stock?

Wow wow wow.

In the beginning I thought, yeh right mate, how long until this one is aborted...

As I scrolled down, my jaw dropped at your skill and my underestimation!

PS, do you fancy doing another intercooler like that?
I have purchased a big front mount but I really do not want to modify the cross member, which id have to do.

Superb work!! Please keep us updated

+ 1 on all the congratulations! Look forward to reading about this and seeing some data logs.

Update 6

Thanks for all the encouraging comments its taken a fair amount of time and some serious work but I think its definitely worth the effort.

So the car has been started since my last update and all is well. There are a few minor things to be done which is to be expected with so many changes but they wont take long.

When the car is running and all back together I'll get a video for you all to have a listen, I personally think the twin-scroll gives the car a different sound and its not the exhaust as my dads 951 has pretty much the identical 3" exhaust and they don't sound the same.

Here is a few pictures of the car now.

This is the turbo bolted in for the last time.


These are the wastegates and cross-over in place. I will be interested to see how they perform. I've seen many similar setups on other cars which worked fine and I don't see why they shouldn't but time will tell. Currently they are dumping under the car for testing and to make it easy to change wastegate springs and the like. However they can be quite easily piped to the centre tunnel and ultimately I'd like them exiting behind the drivers door.



I have also received my new AOS cap
You will notice it sits quite low, this is due to the current intake manifold being spaced out from the head to give more room for the turbo. The top of the engine will be very much unfinished until I get my intake manifold and new intercooler made.



This the engine bay from the top.


Hope this is of interest and if your looking forward to the results then you can imagine how I feel

Definitely of interest and thanks for the comprehensive posts. Really like what you've done here. I might have followed suit with the brand of turbo had you paved the way previous to our build.
Going to be interesting to hear it at full noise especially with the twin open gates!

Interested what you mean when you state that you've spaced the stock intake further away from the block to make room? How / where have you done this? Do you mean that the intake runners are actually longer?

I think has spaced the inlet where the gaskets go on the head, I had to do the same to clear my turbo.



The difference will be that mine are rather crude and his will be art.

Update 7

Just a quick update to let you hear the car running in the garage.
This is without any tuning done what so ever.

If all goes well I'll have the car out of the garage tomorrow and it'll be getting a road tune.

good stuff, looking forward to seeing results on this turbo setup!

Update 8

So the car was out today and took it up the road for a spin.

First impressions are that the turbo is a lot more responsive than expected.
This duel scroll stuff really works!

The other surprise it the turbo makes a far bit of noise.
I expect its the fact the BOV it integrated into the compressor housing but when dumping air it does sound somewhat like the Mclaren P1 Not a bad complaint!

So at the moment my wastegate springs are 0.5 bar which don't seem to be opening at all which indicates my back pressure is low.
This means I was limited in tests but this the information I have.

Looking back through my logs my boost threshold is as follows:
0.2 bar = 2124 RPM
0.3 bar = 2191 RPM
0.4 bar = 2305 RPM
0.5 bar = 2416 RPM
0.8 bar = 2750 RPM
1 bar = 2880 RPM
1.2 bar = 3017 RPM

Also as regards response if I step on it at 3150 RPM I see 1 BAR at 3350 RPM this is approximately 1 sec
Another example is started at 3400 RPM and 1 BAR is seen at 3550 RPM

This is all with a very poor tune with AFR's between 10.5 and 11.5 with is far to rich.
Im going to aim for 13 below 3000rpm. This is to raise EGT's and to help spool up while not over shooting 13.3 which is lean best torque.

Considering the EFR 7064 has a big turbine as well as the fact it has a 1.05 A/R housing it goes to show with a combination of the Gamma-Ti turbine and the dual scroll housing seems to produce the results. This should also mean the car is very free revving which I'm looking forward to.

Its safe to say I'm very pleased and looking forward to driving the car for the next 6 months.

I will update you with a video and the final results from this turbo soon may even get to a dyno.

Brilliant results. I have often thought a twin-scroll would work well on a 944 Turbo and you've more than proved it here.

I think the issues people get with back pressure are to do more with the turbine and housing than the double crossover pipes. Thinking logically, the 2 pipes give you a greater escape area than the original single pipe.

You have a decent size turbine and turbine A/R roughly equivalent to 2 x 7cm2 housings with a T4 size flange which is perfect for fast-road use.
To be honest I think an even larger turbine set-up would work fantastic but is clearly not necessary for your application.

The EFR's are well-designed turbos. They've even paid proper attention to the turbine outlet.
I hope I can eventually get my twin-scroll set-up working something like yours. The eventual aim is to fit a Holset HX35. That has a 70/60mm turbine with a 12cm2 housing so roughly equivalent to 0.89A/R.

I think you've paved the way for other 951 owners

P.S. Makes you wonder whether ITB's are necessary with the kind of response you already have but I definitely would - why not when you have the skill and know-how?

Sounds great, exhaust looks great as well. Is that spool up in 5th? If so very similar to my gtx. Need to get my final tune dialed In and dyno

Not attempted to make adjustments to my tune myself yet. How u Fi do the software?

The spool up was on back lanes in 3rd. Not really that accurate as have to be very carefully with this turbo not to over boost. Once it gets near 1 Bar things happen very rapidly.

I expect the biggest difference between the EFR and GTX will be transient response. The response on the EFR is electric when you get over 3000RPM. This will be due to the smaller compressor. Also I have a bigger turbine and with a 1.05A/R housing it should flow lots of air when I get my head work done. I've calculated that I shouldn't get more then a 1.3/1.5 turbine back pressure to boost ratio. This should be fine on a fast road/ track car.

One of the things I was also very pleased with is my IAT's were only 5/6 degrees above ambient. The smaller compressor will probably produce more heat but I intend to fit a BIG front mounted intercooler, direct port water injection and intercooler spray bar to take care of this. My EGTs are also considerably lower than when using the K26/8. This isn't helping my spool so I intend to lean things a little to bring the EGT's up at lower RPM's and with AFR's around 10.5 Ive plenty of room to play with.

Toms software is great, the best part of the package in my opinion. Any timing alterations I do before on the road and then just concentrate on fuelling when on the road. You will need someone to drive the car to make it easier. Its important to spend lots of time on the cruising part of the map as this will affect your everyday driving the most. Its also the easiest whenever your starting out first.

Timing is the big part that you can only really do properly on a dyno. Tom will give you a steer as to what is safe and thats the key part keep it safe until you get on a dyno and do it properly then. My car is currently running ridiculous timing. Ive taken out 5 degrees to keep it safe incase of over boost. Once I get things working as they should I'll start putting it back in and see how things go. Nearest dyno is nearly 2 hours drive and its one of only a handful in Northern Ireland so when I go it'll be for a day.