Bri Bro

If memory serves me correctly, he was in the $900-1000 range and he had NO takers at that price. The Lindsey solution of separate harnesses seems to be working in place of a complete harness for most.

incomplete

i totally hear you. i rebuilt a donor loom for my build, which took a loooooooooong time and involved a lot of measuring, cutting, crimping, etc.

someone once asked me to rebuild their loom, and i quoted them 2k. $200 parts, $1800 labor. they, obviously, said no.

this is the ridiculousness that ensues... start here and click forward for a few pics:

https://picasaweb.google.com/1009528...59443717134546

blown 944

Back to the track again tonight..

Josh and I were talking last night and he said "what"s the point?"


Well I decided to go anyway to see if I could get a handle on launcing the car better. Well, he was right, without tires it is just pointless. I either bog it or spin horribly. I think I was spoiled with the MSD 2 step and sticky tires.

I ran a couple 12's and mostly low 13's. My MPH was also all over the place from 109-115.

I am still running low boost (>12psi) since the miss I thought I had squared away keeps coming back at the track. I think I've narrowed it down to a rich mis-fire since the track is a much higher elevation and the logs look like it is a bit rich up there. We had never really tuned for this boost pressure and I am on a custom tune so it has some different things going on.

This is the third week in a row I've ran it and other than the mis-fire it has been flawless. I have to admit that even with it running at low boost it does run pretty darn well. I do really want to turn up the boost, but I have been being very good about leaving it completely off and trying to get some good baselines. This is so unlike me but I just have to make sure the engine lives for all the testing I plan on doing with it.

I am hoping we can get a few things done this week in order to be able to maximize this boost level. I'd like to get the cam installed and I am for sure running my drag radials if I go up this weekend.

So far the best at 11.8 psi is 12.63 @114.8 and the best MPH at this pressure is 115.9.

If I can manage to get a clean run out of it I think it'll do OK.

I've been driving it every day and so far so good with the el cheapo stroker

V2Rocket

thats about what an LS6 corvette runs down here on earth...that you can pull it off up there means you've got something big going on...

OverkillMotorsports

I was thinking the same thing as Josh, but knew you would be at the track regardless. Carl was down there in his BMW again and said he bettered his previous best. Nothing like racing all night and driving the same setup home. That motor needs boost Sid so light the wick already!

blown 944

Jared, I know I need to turn it up. You know how i am though. Once I do that, I don't worry about the other stuff. I will eventually. I have so many things I want to quantify first.

V2Rocket

Porschevtsubishi?

With maybe a Dodge Ram turbo

refresh951

Once again, great input! Thanks Sid.

95ONE

I love you Sid. You're like my Rennlist twin brother. But it is this point that we completely disagree. Here is a statement on Borg Warner's Website. I have math to prove it. (math also proves you can't ever actually touch something, but you know what I mean) The only loss of power you have is that maybe the compressor is less efficient at the higher differential. - Sometimes it's actually MORE efficient at the higher differential depending on the compressor map and your setup. The loss of time you have is spool time to get there. Minimal at best on either front for power and time loss. Naturally aspirated is of course a completely different story.

http://www.turbodriven.com/en/turbof...dvantages.aspx

Quote from link above.

"The high-altitude performance of a turbocharged engine is significantly better. (than a naturally aspirated motor) Because of the lower air pressure at high altitudes, the power loss of a naturally aspirated engine is considerable. In contrast, the performance of the turbine improves at altitude as a result of the greater pressure difference between the virtually constant pressure upstream of the turbine and the lower ambient pressure at outlet. The lower air density at the compressor inlet is largely equalized. Hence, the engine has barely any power loss."

blown 944

I know we differ on this point but I've seen enough Evo's, WRX's, etc run so much slower up here (14's) with the same mods that I feel confident in stating this.

Hell I flow a significantly less amount of air going from where I live (generally 6500 da) to the track (usually over 8000)

I'm sorry, just what I see. That may be true for going from sea level to 1-3000ft, idk. Doesn't seem the same up here. I guess you'd have to experience it to know what I'm saying.

It always seems like in working the engine quite a bit harder to get the same power compared to where I live. Every other racer I talk to feels the same. We'd all like to move the track down here...

refresh951

I think theoretically this is true, but the turbo has to deliver. The turbo must work harder to deliver the air. This results in more heat, more heat, more loss. Also at altitude the IC will be less efficient. I think at 8000 ft everyone losses power although a turbo in general would loose less than an NA.

Rogue_Ant

Bruce, that link has bit of marketing hyperbole, and definitely leaves out a lot of important assumptions & info.
I will match any math you want to put up, and I have the empirical data to back up the "theory" that vehicles, turbo or not, are less powerful up here.

Being at this altitude means that you are at a higher differential on the compressor. This means that the turbo is generally having to hit a higher RPM, to make up both pressure and flow. This is absolutely not a free-hp situation. As you know the classical kinetic energy formula E = ½ mv². The energy required to increase the turbo RPMs is not a linear relationship. The velocity is squared, so any increase in velocity is going to require a velocity change squared increase in power.

One might say that the "lower post-turbine pressure" equalizes this, but then they are forgetting entropy: that their is unusable energy losses any time energy changes from one form to another.
Additionally, as Shawn mentioned there is adiabatic losses from having a higher pressure differential. If we look at the compressor, even assuming an ideal compressor (100% efficient), compressing air produces heat (ideal gas law). Having a lower starting point (atmosphere), means we have to compress the air just to get back to sea-level. To achieve the same 15psi in Denver as sea-level, we generally have to compress the air an extra ~3psi. More compression = more heat.

On 99% of turbo cars, there is not a 1:1 manifold pressure relationship (post-turbo intake pressure vs pre-turbo exhaust pressure). Generally, the relationship is 1:1.5 to 1:2.5, specifics-dependent. This further diminishes the "lower post-turbine pressure" advantage. Even if we assume no entropy, no turbo RPM change, and no adiabatic losses (all are ridiculous assumptions), and just apply the intake vs exhaust pressure ratio, then we are still at a dis-advantage.
For example: Assume X setup has a good 1:1.5 ratio. At Denver altitude, there is 3.0psi less air pressure than sea-level. So we need to make an additionally 3psi of intake pressure to account for the lesser atmospheric pressure. Then by the 1:1.5 ratio, the turbine side needs an additional 4.5psi of drive pressure... 4.5 required is greater than the 3.0 gained from less post-turbine pressure. Therefore, we are, again, losing power.


So, anyone that feels different: I lay out this challenge. Run your car, 1/4mi, at/near sea-level. Then come up here (you won't find a better prepped track), and run your car again without any changes. I do not care what your setup is, you will run a slower MPH.

95ONE

OK.. given the fact that your (Edit: NOT SIDS turbo, ANY turbo that might be maxxed, or far right on the compressor map.) turbo is already maxxed out. Sure. It has no room to make up any additional pressure differential because it's already maxed out from sea level, that it will then have the illusion that the air density is the problem, when in reality, the turbo was already turned up past it's abilies. Possibly any examples you've seen? So, they will lose power yes. If I were from a higher elevation though, I might make sure this isn't the case? Even down here, I had a turbo that had plenty of room to make up the difference.

Rogue_Ant

Turbos that are near maxed out (flow or pressure) will not be able to make up the needed pressure and flow - making the altitude effect more dramatic. I agree.

However there are plenty of cars running up here with turbos that are not maxed. And they too run slower. Your GT30r car would have run slower here. Just because the turbo is not maxed, does not mean that it can make up the loss of atmospheric pressure for free. The turbo is working harder, that energy must come from somewhere (conservation of energy / 1st law of thermodynamics).

We can argue about it all day long, but the simple fact is cars run significantly slower up here - pull up youtube and watch videos of street cars at bandimere if you like.

Or take me up on my challenge, get a turbo car and bring it up here.

blown 944

The problem is exactly what you just stated. In order to even get to a decent state of power, you have to run a larger turbo (much larger). I'm sure you understand what kind of problems that creates.

If we were talking about a strictly drag car running a huge turbine housing and anti lag, launching at full boost, etc.... The comparison you cite may be closer to justify your argument. However, that is not practical at all. Even then, the energy required to just for spooling the turbo is quite a bit greater.

I know this your position, I'll respect that. I am just not going to agree with it. Just like pressure doesn't necessarily mean hp. There comes a point where you are wasting a lot of energy and not making gains. The same applies to running a turbo harder to create the same airflow.

There are some YouTube videos of cars running up here that should be running much faster mph. Check them out. In particular, supercharged LS vettes, Evo's, WRX's, etc.

It just is what it is. I have driven my sons car down to AZ, and I know first hand there is a significant change in power. (4g63 car)