- Thread starter
- #2,421
Ironically Gale Banks of Banks turbo just did this video 4 days ago that was recommended in my Youtube feed but he demonstrates the power loss in the video when NA.
Bolt on turbo kit (4 Viewers)
- Thread starter scottryana
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I agree it will provide a consistent manifold pressure reading at the gauge however in absolute terms the amount of air being pushed into the engine will less as the elevation increases (assuming a mechanical wastegate). In addition the intercooler efficiency will be reduced due to the thinner air.
I like the compressor maps since they show how the turbo can compensate to a point but then efficiency falls off.
In either case it will be so far superior to N/A that nobody will really care
Just wanted to point out that a turbo at sea level does not exactly equal a turbo at high elevation.
- Thread starter
- #2,423
We can disagree, mechanical wastegate will maintain the same absolute pressure, because it is connected to the manifold pressure so to overcome the spring at sea level it will overcome 14.7psi atmosphere + 6psi boost (20.7 absolute) at altitude it will have to overcome 11.7psi atmosphere + 9psi boost (same 20.7psi absolute)
I agree it will provide a consistent manifold pressure reading at the gauge however in absolute terms the amount of air being pushed into the engine will less as the elevation increases (assuming a mechanical wastegate). In addition the intercooler efficiency will be reduced due to the thinner air.
I like the compressor maps since they show how the turbo can compensate to a point but then efficiency falls off.
In either case it will be so far superior to N/A that nobody will really care
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I agree it will provide a consistent manifold pressure reading at the gauge however in absolute terms the amount of air being pushed into the engine will less as the elevation increases (assuming a mechanical wastegate). In addition the intercooler efficiency will be reduced due to the thinner air.
I like the compressor maps since they show how the turbo can compensate to a point but then efficiency falls off.
In either case it will be so far superior to N/A that nobody will really care
The difference is that a turbo is free to spin faster and therefore, increase the MASS of air being put into the engine. A positive displacement supercharger has a fixed-volume rotor that can only get so much VOLUME with each rotation. As elevation increases and the density of air goes down, the total mass of air also goes down because the rotor of the supercharger is directly related to the RPM of the engine.
I agree that the turbo is free to increase its rpm unlike the fixed rpm of a supercharger. What I'm trying to convey is that the absolute amount of air pushed into the engine will decrease as elevation increases, assuming the use of a mechanical wastegate, however the pressure ratio will remain the same as at sea level (example +6psi above whatever the air density is at a given elevation).
In a more complex boost control system the absolute boost pressure could be maintained, however this would require inputs from barometric pressure, temperature and humidity sensors so that the actual air density would be known. This feedback would allow the electronic boost controller to calculate the actual air density and then compensate the boost pressure as needed to maintain an absolute level regardless of elevation. At some point (probably at an elevation higher than any roads in the US) the turbo would be spinning much faster than its efficient range and absolute pressure could no longer be maintained.
Here's some interesting reading regarding the topic:
US6178748B1 - Altitude compensating wastegate control system for a turbocharger - Google Patents
- Thread starter
- #2,426
Incorrect you have it backwards. In an electronically controlled boost system the ECU will open the wastegate to maintain your set boost if that is 6, 15, 25psi, you can set that to relative or absolute depending on what reference you are using. That is why modern ECU's have temp and barometric ports built in. In a mechanical wastegate system the only thing opening the gate is the MAP pressure vs the EMP.
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HDJdreams
SILVER Star
In short a turbo DOES handle elevation better than naturally aspirated. Great because there’s plenty of that out here.
Gale Banks did a great series on air mass and why it is the most important thing.
The Boost Gauge is Dead to Me!
Tech Talk 3: Superchargers and Turbochargers
They guy is 77 and still a beast. We should all be so lucky to have learned as much and be in as good shape if we make it that far.
The Boost Gauge is Dead to Me!
Tech Talk 3: Superchargers and Turbochargers
They guy is 77 and still a beast. We should all be so lucky to have learned as much and be in as good shape if we make it that far.
I like turbo.
NLXTACY
Wits' End
Well I got some good news finally.
Everything is repaired on Dylan’s test mule and the last cold start test is at 9am and will be ready to pick up at 10am in the morning. I’ll be leaving and going directly to Weistec in Anaheim (apparently Home of the world’s fastest Mercedes, meh) for the 4WD dyno pass. Immediately after I will be heading to Flagstaff. I’ll be taking the train back to LA on Monday and then picking up my LX at SEMA and going back to the dyno shop where I will dyno my SC’d truck. Two birds.
@alia176 you bringing your own beer mug or do I need to supply one?
Everything is repaired on Dylan’s test mule and the last cold start test is at 9am and will be ready to pick up at 10am in the morning. I’ll be leaving and going directly to Weistec in Anaheim (apparently Home of the world’s fastest Mercedes, meh) for the 4WD dyno pass. Immediately after I will be heading to Flagstaff. I’ll be taking the train back to LA on Monday and then picking up my LX at SEMA and going back to the dyno shop where I will dyno my SC’d truck. Two birds.
@alia176 you bringing your own beer mug or do I need to supply one?
- Thread starter
- #2,431
Haha I would love to see the looks on Weistec's faces. Please get some video of the dyno.
Also some advice on the dyno.
Use the 2nd gear start button and put the selector in 2nd gear. This means your dyno run will be in 2nd instead of 3rd which is the 1:1 gear and is usually preferred but you will be able to actually lock it in gear so that the truck won't try and downshift when they go WOT. It is important that they use the 2nd gear start button or else the truck will shift down to 1st on acceleration.
Nice work Joey!
Also some advice on the dyno.
Use the 2nd gear start button and put the selector in 2nd gear. This means your dyno run will be in 2nd instead of 3rd which is the 1:1 gear and is usually preferred but you will be able to actually lock it in gear so that the truck won't try and downshift when they go WOT. It is important that they use the 2nd gear start button or else the truck will shift down to 1st on acceleration.
Nice work Joey!
Well I got some good news finally.
Everything is repaired on Dylan’s test mule and the last cold start test is at 9am and will be ready to pick up at 10am in the morning. I’ll be leaving and going directly to Weistec in Anaheim (apparently Home of the world’s fastest Mercedes, meh) for the 4WD dyno pass. Immediately after I will be heading to Flagstaff. I’ll be taking the train back to LA on Monday and then picking up my LX at SEMA and going back to the dyno shop where I will dyno my SC’d truck. Two birds.
@alia176 you bringing your own beer mug or do I need to supply one?
alia176
SILVER Star
This is good advice for those of us who has never dyno'ed before and would like to do a pre and post turbo install. Thanks dude.
Very cool that you're using Weistec's facilities...... I have most of their stuff on my C63.... great product and support team.
I recall the look on their local dealer's face when I asked them to Dyno my old built 200 ( w/ Kooks custom headers and Catback)
I recall the look on their local dealer's face when I asked them to Dyno my old built 200 ( w/ Kooks custom headers and Catback)
- Thread starter
- #2,434
We struggled to get a real number - it broke 2 straps which was a bit more than exciting..... and it was 98 degrees along with a MAF that later was replaced. so factoring in a 28-30 % loss along with that it's not all th
at impressive.... but the butt dyno seemed to put it at 40-50hp gain with the headers and low flow exhaust
NLXTACY
Wits' End
Ugh. Truck testing pushed back til 2pm. That puts me in AZ by midnight if I’m lucky. Ugh.
- Thread starter
- #2,437
Ok good to know. So that 286awhp was after headers and and exhaust? So my 281awhp estimate probably wasn't too far off. Maybe 265-270awhp without all the exhaust parts.
Ugh. Truck testing pushed back til 2pm. That puts me in AZ by midnight if I’m lucky. Ugh.
Rebull, Monsters and Coffee!
All mixed together and beer bonged
Did someone say dyno pictures? 121.5 HP of japanese tractor! 
