The bearings took excessive clearance because of the axial load from the helical cut gears. So the synchros began to crack and finally the metal parts inside grenaded the gearbox. (the gearbox was still working but cracking and shifting was very hard)
My use is mostly pretty long pulls from rolling starts and I broke 2 oem gearboxes this way.
I do not understand how more powerfull cars as AIM's, Mark, Zlatko, Rix and else can hold?


Regarding the power I guesstimate about 1000bhp yes.

 

Mostly the torque, I ran friend's 850 to >1000hp cars with low torque and power until >5000rpm, their gearboxes hold...
My car runs the same 60-130 time in 3rd+4th than all in 4rth, already 740lbs/ft @3500rpm according to the dynotool from the performance box report.

 

Not so much my friend! I just found the sheet: max torque 850lbs @5200rpm (1150Nm) and 740lbs / 1000Nm @3500rpm.

(max boost is "only" 1.65Bar/24psi)

 

This car is very impressive

 

Congrats on your ride this is one wicked machine..following your posts it seems like I read that you go to the track ..can you explain behavior of turbo when tracking and how much bigger is this turbo compared to the 3071..wpould it be the same size as like a 3073or would you compare it to a 3076...also how did the turbo run on pump gas ...
Thanks for your detailed posts learned a lot..

 

Those turbos spool almost as early as the 3071 but only if your boost target is at least 1,4Bar 20psi, a kind of pressure you can't afford with straight pumpgas.
@1,25 Bar (max boost with straight pumpgas for peace of mind IMHO) they spool a bit later and the boost build slowly vs the 3071, but they pull better above 5500rpm, you can feel it.

When I track the car I run straight pumpgas (and sometimes a can of octane booster for safety) and my EBC A mode: 1,25Bar and almost no overboost nor ramp up at top. This way the 3071 were a bit better.
Reason is we run the gas bought near the track and no E85 everywhere here.
At Le Mans I ran E85 and the EBC B mode (1,45Bar, overboost and ramp up after the peak torque) and it was great. Also did a few laps on C mode (1,65Bar etc...) but no grip enough and such an heavy car at the speeds you reach becomes hard for the brakes and tires.

 

So how much power did you have on pump and e85 on the 3071s...seems like this turbo might be my next upgrading from stock...

 

I didn't run the 3071 with E85, only the Xonas.
I remember the 100-200 was 5,5´/5,7' and the 100-300 was about 18'-19' (pumpgas).

Nevertheless the 3071 compressor design must be a bit old fashion nowadays, why not the Xona xr5456? They might spool same as the 3071 with more top end.

 

Hey P, car sounds like a beast! Are your turbos same as mine? Mine are called xr980 but sound similar to yours I think. You said not to go higher than 1.25bar on pumpgas, why is that? I only have pumpgas, and I think wastegate pressure alone is 1.25bar lol

 

Hi Asher,
Reading your thread yes I believe our turbos are pretty similar.
Mines are XR5756 externally gated.
My multiple dataloggs showed me our Euro 98 pumppgas begins to knock about 1,35Bar boost with our turbos and a correct ignition angle.
As I can run E85 easily around home for performance I do not map above 1,25Bar whith pumpgas for extra reliability.
I agree with Andreas your waste gate basis boost seems high to me.
I did several tests with my MVR44 (a bit large for our turbos, the 36 should be enough) and I ended with 1,1Bar WG basis boost for a daily 1,65Bar target (E85 from pump which is more E70-75 when checked)

 

Your turbos are the same. Unfortunately aftermarket can't stick to a turbocharger nomenclature. Both are what would have been called 3073 in the past. GT30 turbine wheel and 73mm compressor in this case HTZ. The 5756 naming = 57lbs/min and 56 is exducer on turbine wheel. The actual exducer on the wheel should be 55mm so the 56mm could be the bore on the turbine housing. Doesn't matter same wheel lol. XR980 I imagine is in reference to power output. All out these turbos should end up around that number at the wheels. Or you can call that number flywheel if you want to under rate your turbos. I don't know what they are claiming.

 

How much knock are you talking about around 1.35bar on pumpgas? I'm seeing -2 in 1 channel for a short period with my pumpgas on about 1.35bar.

 

Very possible at 1,35Bar; I do not want no knocking activity at all that's why I lowered a bit the boost with pumpgas.
In the past I grenaded my 993TT engine because one knocking sensor was out.
Since I do not want to run with the least knocking activity in regular conditions, I mean with fresh pumpgas, usual target boost and regular AT.
With E85 there is much much room before knocking with the moderate boost I run.