BC

I think the E85 issue is that it does require a MINIMUM amount of "best practices" to have a long term success. Rubber does need to go in the long run, as over time I think that the ethanol will not dissolve, but soften the material and cause issues. Just to be safe, I am using SS hardline instead of aluminum, and any softline that I use will either be teflon lined (ultra flex 650, goodridge teflon bore, etc) or rated for E85 (supposedly, Twist-lok from russel is approved)

DanaT

This wednesday. I am actually home on a weekday.

I hope to be there when the gates open at 4.

-Dana

Rogue_Ant

Crap - I'm not going to be ready to run... But I'll try to make it anyway if you guys are going.

blown 944

Probably not going to be coming up early at all. Manning the shop solo this week and getting behind already...If I come up, it will be later.

DanaT

I am leaving around 3pm to get there. Hope to see you guys.

-Dana

Rogue_Ant

I'm not making it. My better half just got a new job, so we are out to celebrate!

blown 944

Nice to see you again Dana,

didn't get to stick around and see what it did on the last run (assuming last run since there was an oil down and we left ).

Looked like you were creeping up on it pretty well. Gonna try harder to make time next week to bring mine up. Or see if someone is doing a private tune session soon.

Rogue_Ant

Ok, so what times/speeds?

DanaT

Times....too embarrassing...best was a 14.7 with lots of wheel spin.

MPH was 103 on 15psi.

But what I must say is the night was a great night in the fact that there was some good troubleshooting.

Sid. I owe you beer.....with any luck no damage was done to the turbocharger and if it is OK you saved me long term damage. It will take a little bit to see if the turbo is OK. Thanks!!

-Dana

333pg333

What happened?

Rogue_Ant

Ha - don't be embarrassed. Everyone thinks that straight-line racing is easy, but that simply isn't true. AND up here at altitude, expect your times to be ~1 second slower then sea-level.

BTW if your 15psi of boost is a gauge reading, then your really only running ~12psi. We lose ~3psi up here...

333pg333

Life's tough at the 'top'.....

George D

I remember running my turbo cars with a MAF up to 8500’ and the boost were the same in LA and in Greer, AZ at 8500'. I'm now using MAP, and it's the same. If you are running MAF or MAP, the turbo will be running harder at altitude, but should produce the same boost whether at sea level or at 9000' to its max capability of producing boost. The original barn door intake of the 951 may not do well at altitude, but I'm not one to know. I do know that it opens based on pressure, so I'd assume this old school metering would be similar to MAF or MAP.

Granted the turbo is boosting thinner air, and spinning faster at the same boost levels as at sea level, but your boost gauge should register boost pressure accurately whether at sea level or in mile high country. If I lived at 5280' or above, I would have a slightly larger turbo than what would be necessary at sea level (assuming similar real world consistent HP) to compensate for the thinner air. More lag, but similar top tq and HP, with max TQ being later in the RPM's. Top end HP would be similar when using the same motor.

What you will find is there is more lag on a turbo car at altitude. It's harder to compress thinner air, hence more lag. Small turbo gas 4 stroke airplane motors like what is in the good old Cessna 210T Centurion have similar HP at sea level up to 28,000' because of the use of a turbo. Realize the power drops after 17,000', but that's much higher than any 951 or most cars care to take a spin.

It's the lag of the turbo trying to compress thinner air, and the later rpm onset of tq that makes any turbo car slower at altitude.

If your gauge is accurate, you are getting what it states in terms of boost readings going into your manifold.

Rogue_Ant

I'm getting really quite tired of this old misnomer.

https://rennlist.com/forums/7029239-post42.html

https://rennlist.com/forums/5622707-post207.html

https://rennlist.com/forums/4693930-post6.html

https://rennlist.com/forums/4333882-post62.html

Gauge pressure != absolute pressure. There is a reason why things are labeled Psig or Psia. Gauge pressure is differential, and will NOT show the ~3psi loss of air pressure up here. Absolute pressure, obviously, will show the lower air pressure.

Here is a good page showing the pressure difference:

http://www.crh.noaa.gov/bou/include/...webpres_16.txt

The first one, Denver Intl Airport, atmospheric pressure is 12.127psi. The mean sea level pressure is 14.676psi. A 2.549psi difference. But normal boost/vacuum gauges are not going to read -2.6psi with the engine off. No, they will read 0 - because they measure the pressure differential between manifold and atmosphere.
So, if the gauge reads 15psi boost, then that is the difference between manifold and atmosphere, which the sum is 27.127psia. The same car at sea level, running 15psi of boost (the difference between manifold and atmosphere), the total is 29.676psia. Obviously the difference is in the starting pressure, IE atmosphere.

Compared to sea level, at the same gauge pressure, we at altitude are running less absolute pressure, nearly 3psi.

Rogue_Ant

You said it