boost at 6250 ft altitude
01-21-2013, 08:13 PM
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01-21-2013, 08:34 PM
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Rick, in theory you could pulley up to make the same boost and roughly the same power as sea level without changing the tune. But... your idle, part throttle transition, acceleration enrichment, and cruise AFR are all still going to be pig rich. Unfortunately it sounds like you just don't have a very good base map as the EFI should compensate for the altitude. Yes, you'll be down on power but, you shouldn't be running rich and stalling. At 900hp with a 598 I'd guess you're probably only running 5-6lbs boost. I don't know what blowers you have but it should be easy to add a few more pounds to get your 900hp back. You shouldn't need two tunes unless the EFI software has very poor resolution. I'm not sure what system you're using but it should be possible for a good tuner to set you up so that if you're at 6000' one day and want to boat at 3000' the next day all you have to worry about is fuel.. Might want to get the tune dialed for the higher boost at sea level too! 
Anyone know of someone with experience with this injection who can use a laptop and O2 sensor and tune my motors here at Lake Tahoe?
01-21-2013, 08:35 PM
#13
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Rick, I used to spend a few weekends every year at Tahoe with my Jag. It has Phaff 598's with 1071 mooneyhams but it is carbed, not injected. I have a set of pulleys for 6000 ft. and a set for sea level. I idle a bit fat but it runs out nice. I would jet my old boat at elevation, no blower, but changing pulleys is way faster and superchargers are cool. That lake will humble you as far as top speed. Slow water and elevation equals slow speeds. 20 mph slower than sea level with na motors, not quite so bad with boost motors that are set up right. Doug
01-21-2013, 08:37 PM
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So, no matter what I do I will need to tune the injection to have them run properly. Otherwise regardless if I stay at my current boost or up the boost for my elevation, to do this properly it needs to be tuned.
Anyone know of someone with experience with this injection who can use a laptop and O2 sensor and tune my motors here at Lake Tahoe?
Anyone know of someone with experience with this injection who can use a laptop and O2 sensor and tune my motors here at Lake Tahoe?
01-21-2013, 08:41 PM
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Rick, I used to spend a few weekends every year at Tahoe with my Jag. It has Phaff 598's with 1071 mooneyhams but it is carbed, not injected. I have a set of pulleys for 6000 ft. and a set for sea level. I idle a bit fat but it runs out nice. I would jet my old boat at elevation, no blower, but changing pulleys is way faster and superchargers are cool. That lake will humble you as far as top speed. Slow water and elevation equals slow speeds. 20 mph slower than sea level with na motors, not quite so bad with boost motors that are set up right. Doug
No problems like this at sea level.
01-22-2013, 02:58 PM
#16
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It's been covered - but
Yes, you repulley to 5 psi more than you ran at sea level, and your motor will be ingesting basically the same amount of oxygen at WOT as it did at sea level and should make around the same power and be at appx the same AF ratio.
At anything less than WOT, though, your calibration will depend on what MAP factors have been programmed into the FI system. If somebody set it up at sea level and did not plug in MAP factors for wide pressure variations, then that would be part of your problem.
A guy used to tuning for wide altitude variations will be familiar with how to plug in those factors which should result in your motors running the correct AF ratio whether you're in death valley or on Pikes Peak. Your power, of course, will depend on how much air you pump through it.
A cheap fix for your lack of top end is to bump the boost 5 psi. It won't fix your rich conditions though.
MC
Yes, you repulley to 5 psi more than you ran at sea level, and your motor will be ingesting basically the same amount of oxygen at WOT as it did at sea level and should make around the same power and be at appx the same AF ratio.
At anything less than WOT, though, your calibration will depend on what MAP factors have been programmed into the FI system. If somebody set it up at sea level and did not plug in MAP factors for wide pressure variations, then that would be part of your problem.
A guy used to tuning for wide altitude variations will be familiar with how to plug in those factors which should result in your motors running the correct AF ratio whether you're in death valley or on Pikes Peak. Your power, of course, will depend on how much air you pump through it.
A cheap fix for your lack of top end is to bump the boost 5 psi. It won't fix your rich conditions though.
MC
01-22-2013, 09:33 PM
#17
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1000' elevation = 5% power loss. 1 pound of boost = 5% power gain (on average - rule of thumb). 10 degree drop in temp = 1% increase in h.p. A 25-30% loss of power would make most any grown man cry! Good luck.
01-22-2013, 10:22 PM
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Call Brad Johnson. He knows a lot about making horsepower out of thin air. He's a Tahoe legend and a nice guy. I can't remember his company name. Sorry. Doug
01-23-2013, 02:35 AM
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Contacted them and responded, requesting that I don't need a license, they can password the box. here is their reply:
Rick,
You will need a software license and programming cable unless you already have a registered copy of the the tuning software. Do you know if the engine map was password protected by the previous engine builder. If so you will have to return the ECU's to us to have the password removed.
Software license $1,595.00
Programming cable $295.00
On site support is $850.00 per day plus expenses. Tuning should take no longer than 2 full days for both engine configurations.
Regards,
