Mythbuster: continuing project thread of my 1303 '75

[Wally]

All parts in da house and making it all fit went well (I'am getting almost a routine in this ):



Went for a first test drive today
Needed to set-up the EBC again and by accident selected the wrong button...which led the boost rise to 30 psi before I backed off...
Fortunately all corrections and setting were entered up to 2 bar boost and the engine suffered no harm apparently. I did get launched pretty well though
Spool-up is indeed a lot slower as expected: I measured about +800rpm in the log before 15 psi was reached. I also must confess I checked the headers I welded and saw about 4 or 5 small leaks... so maybe spool will improve some when I have solved the leaks. Initial boost threshold seems a lot less slow and impressions are only about +500rpm for boost threshold.
I would have expected about +1000 rpm considering the size of the new turbo and all the extra volume in piping, so I am actually still vary happy already with spool as it is

Outside temp today was very cold: around freezing point: 0 Celcius. Intake air temperature was only 4 Celcius under boost. Air-air intercooler FTW

The most important benefit I saw from this turbo is that EGT was much lower throughout the whole rpm range, even when cruising! I had a lot to keep an eye on today, but if I had to make a guesstimate, 50 Celcius lower at least, maybe even 70-80 Celcius, but will have to investigate that when I have driven more.

I also have anothe HKS (SSQV) BOV installed and that seems to work well too. Seems to keep the flow more constant after it opens, but hard to tell exactly what/how it works different. We'll see.

Made a little vid in the hope to capture the Borg whistle, but I don't think I can hear it destinctly enough from the inside.

http://www.youtube.com/watch?v=f4iuImkFo0I

[Humble]

I love my borla xr1 it really toned down the exhaust quite a bit. How much rpm are you spinning by the time you hit 1 bar boost now? I know it added a bit more lag but is it tolerable?

I went with hks ssqv bov because a friend was using it in his car. I've found that I can keep about 10psi in the intake between shifts which really helps to kill turbo lag when rowing through the gears. I don't like the whistle though, and just put the recirculation fitting on it instead.

[effvee]

http://www.youtube.com/watch?v=f4iuImkFo0I[/QUOTE]

Hay Walter, man nice work. Question, that G50 has tall gearing, in your video was that 4th to 5th gear? It looked and sounded like you could have continued to accelorate even more. Again damn nice results, congrats.

[Wally]

Yes, pairing 1/3 and 2/4 together is very important and ideally they should be equal length as well as this will give equal spaced exhaust pulses which helps spool. in TS configuraion.

[Sandeep]

Looks awesome Walter !

Might be the picture, but looks like paint on the apron is discoloring a bit, might be touching the header in this area ?

Fantastic build overall.

Sandeep

[Wally]

Good eye! It used to touch over a year ago, not not anymore. Damage was done and I don't mind too much tbh. There's also a little dent there from someone that ran into me in a traffic jam 2 years ago...

[Wally]

4th gear and yes, that was a little over 6K, but it goes on to 7K and wants to go further then... Very curieus untill how far it continues to make power on the dyno.

[70Turbobug]

Congrats Wally! Looks and sounds great!

[judgie]

looking good. be intresting to see the dyno results on this set up compered to the old one. are you going for more boost or was the swap to the bigger turbo to control the boost better?

[Wally]

Originally Posted by judgie

looking good. be intresting to see the dyno results on this set up compered to the old one.

Are you going for more boost or was the swap to the bigger turbo to control the boost better?

Neither actually: this huge turbo was intended for fitting together with an engine upgrade to more cc's. Then a big turbo like this would make more sense. The bigger cc u[pgrade didn't happen however, hence I thought trying it on the current engine I have so much data already from.

The other idea was to decrease exhaust gas back pressure by using an even bigger (compared to the already bigger compressor) turbine wheel.
So, the turbine wheel now is double big so to speak... hence the to be expected huge lag. I think partly due to the twin-scroll set-up, lag is not as terrible as it would have been otherwise.

OTOH, less back pressure will make higher boost settings possible. For example: 20 psi gave me 30psi back pressure(!). You can fill out what this means if you have a (assuming) 1:1 ratio...
Question is will the engine internals withstand the mechanical forces (++torque) of more boost or even same boost but with more power because of the better VE I think I have now?

I tried tuning it on the road, but frankfully, its too tricky on a public road at the boost settings above 15 psi. Tuning is not complete therefore, but close enough
-only one way to find out: drag it to the dyno

[Wally]

Dyno has been booked for coming saturday...

[Steve Arndt]

It will keep on making power until the valve springs float.

[Sandeep]

Fantastic !

Based on your last "seat of the pants" comment, I'm guessing you'll be dynoing to 15 psi then ?

Are you still using the ID1000's ?

Looking forward to the results and the conclusion of your exhaust back pressure / turbine size testing.

Sandeep

[70Turbobug]

IDC at 100% ? Injectors too small also? I figured 1000cc would be enough running pump gas at that horsepower level.Perhaps not enough fuel pressure for the amount of fuel volume needed? In other words rail pressure is dropping because the pump can´t keep up with the boost/fuel ratio and maintain the desired pressure and the injectors try to compensate with longer opening intervals? It´s just a guess - I´m not sure if that makes sense but I can´t imagine that the injectors are too small at that level?

Maybe it´s none of the above and you don´t have enough electrical power/current to support the pump? What I don´t understand is,you´ve had a higher boostsetting,ran richer(?) and HP before the turbo change.So how is it possible that it suddenly collapses?

[Wally]

I have found the cause: my feed pump wasn't running well and I got stranded because it didn't run at that moment at all anymore!
Logical that when you have no fuel anymore, the engine dies out...duh!

I had a spare 944 pump I switched over and it started cold immediately again :mrgreen:
Pffft!
I left the fuel pressure to 60 psi, so according to the flow sheet that should give me 1180 cc, which should be enough anyways. Just need to re-map the fuel map but thats no biggie.

Very glad it was something this simple, but scary as it could have ended far worse. Amazingly and fortunately the engine held...