Discrepancy in power gain, same turbo different cars, altitude and air density is a big reason for a lot of it.

[RAAMaudio]

Corrected the correction I did earlier, 237 WHP at 5k ft is around 270 at sea level w/o aid density factored in, likely pretty cool there the last couple of days which helps considerably.

 

[ColoradoST]

That sounds about right. It was 70? during the dyno.

 

[RAAMaudio]

I always knew there was power loss as altitude increased but the loss caused by temperature increase is more than expected so the two combined explains a lot of why my numbers have never been what expected. Though the EFR was making plenty of power but the lag then sudden hit made the car hard to drive fast in places that made it a bit unsafe. My best Vdyno was actually 320 WHP but just one run after I had just moved from 5200 ft to 4700 ft, temp was likely around 70 degrees, just on 91 Octane, I went with the lower number of 309 WHP for this thread as the 320 was a one time deal.

Now that I have a clearer understanding of just what is happening with altitude and air density power loses caused by the air temp/altitude combination it will help me decide what to do but I still need a bit more info, advice, etc....

1) Stick with the GT2560R with billet wheel, finish 91 tune then 50/50 WMI tune...not sure I will even do the 100% tune now due to safety issues of running it which are VERY SERIOUS, so I would not want to run it and not sure worth taking the time to just see what it will do.

2) E85 and race gas just 2 miles away and good prices, $1.99 and $6.99 respectively if I wanted to play with E30, WMI, race gas and WMI, etc...I think I would rather have straight E30 and a 5th injector instead but spend a huge amount of time doing the safest WMI install I could work out and it is a bit easier to source Methanol in many places or at least carry enough, turn it off when not needed, etc....

3) Ditch the GT2650R and get the Gen 2 GTX2860R , 91 and WMI 50/50 and live with the results...

BUT, I need to know just how the Gen 2 will spool at this altitude, if not much better than the turbo I now have it would not be worth it but if I spins up faster, broader power band, more top end...it would damn well be worth it

325-350WHP at sea level would give me all the power I need, a nice wide power band results in more usable power more often and a faster car more of the time than to big a turbo that is laggy.

 

[1azst]

Posted my gen2 gtx2860 @7000' curves in the big turbo thread. 5000' hits about 200 rpm sooner. 91 and meth 50/50 btw.

 

[RAAMaudio]

Thanks, must be where I saw it but forgot, I will go take a look, thanks

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DAMN that is impressive at 7k ft!

It is really more than I want or need now but likely going to jump on board the GTX Gen 2 !!!

As in the other thread super busy right now finishing up demods, incomplete mod, etc on the dually so the buyer can pick it up and moving out of the toyhauer preps to move into a rig with far more room to live in.

Thanks again for the remind, posts, links, etc