boost at 6250 ft altitude
 

Hi everyone, need some expert technical advice. Have 2003 38 ft cat with twin 598 CI 900 hp supercharged intercooled engines. Fooled around with different props but just didnt run like it did at sea level, especially not getting up to plane even though I could hit the rev limiter with the smaller pitch props. Big difference from a 16 inch 4 blade 32 and a 16.5 inch 5 blade 36. Talked at great lenth with BBlades and they were very helpful.

Theoretically, couldn't I just up the boost enough to make up for the lost O2 at this altitude??? Then, the only difference woud be thinner air for an air entrapment hull - cat - but I can deal with that. I could continue with my original 36 pitch props ( That ran great at sea level - of the line it jumped up to plane and took off, picked up rpms and screamed past 130MPH before I shut it down. Was the most outragious powerful boat I have ever been in (I don't have a lot of high performance experience....).

Besides from running rich at this altitude, the chillers cool the intake charge so much (Thanks to Lake Tahoe cold water) that unless the motors are really warmed up if I drop the drives down at a start and start to push the throttles it just floods the engine and dies. The atomized fuel charge is pooling..... Once really, really warmed up then it's OK. I think I don't have any thermostats in these....

I have talked to various shops. Paul Phaff, Sterling, The Blower Shop, and my local guy. Phaff said they could send a guy to Lake Tahoe and tune both motors for this altitude after changing the pulleys. The blower shop said that 2 or 3 teeth would be equal to 1 pound of boost and that he thought I would need 1 pound of boost for every 1000 ft of altitude over 2500 ft elevation. About 3-4 pounds more boost. But, I have to know exactly what boost I am pulling now, and frankly, I am not sure... Have to take it out and give it a WOT high speed run...! Keep an eye on the boost guages at WOT and 5400 RPM(?).

Phaff said that they could send a guy here who could tune my "EFI" brand injection, even said he could install two tunes and a switch to change from one to the other, one for sea level and one for Lake Tahoe. All I would have to do is change the blower pulleys each time I went to a different elevation and flick the switch.

Here is the kicker, my local guy said: "if you are running rich now, and you want the same O2 level as sea level, why not just change the blower pulleys ( once I am sure what I am dealing with now) to be equal to sea level and the injection should be spot on.....

Phaff most likely would charge $1000+ per motor.....

Anyone here on OSO with experience with this or have any ideas?

Great winter project!

Rick

rick,i dont know if you have afr meter or bungs installed in your exhaust,but if your tune up is for sea level,no doubt you will be very rich at 6500 ft above sea level.you need to spin the blower faster to put more air in the engine.what do you currently have for top and bottom pully,s?

also keep in mind if you up the boost levels your going to make more heat in the blowers..you may have to either install coolers or bigger blowers..turn the bigger blowerd slower at sea level amd up the boost at 6500 feet..

The top pulley has the number 47 stamped on it, don't know yet what the bottom pulley says. I will see if I can count the teeth tomorrow. Send me a pm and i can send you pics of pulleys. No bungs, sterling said they built some of the motors for KE back in 2003 and badged them as KE's. Said it works two ways. One, off of throttle position or two, boost pressure plus throttle position. It literally says on the fuel injection box : "EFI". It's a blue anodized aluminum box with fins.

Rick

It has inter coolers and is way cold blooded. As to heat, the blower shop said I should not go over 8 pounds. I need to find out what it does now...

If the bottom pulley is any number lower than 47, flip those b!tches and hammer it down for a pass :daz:

Actually, after looking at a pic I think it says IFI...

It's logo looks like it says IFI but on the side of the box with the serial number it says EFI Technologies

Funny guy!!! Will find out tomorrow

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! :boat:

They make good reliable stuff. Might be an older box but there should hopefully be newer software for it and it should be capable for what you're doing.

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?

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

Perhaps I should call them! I will google them to see if they are still in business

I drove this boat once at sea level and that spoiled me... I don't need identical performance, but do need it to be able to run cleanly. Have had several embarrassing episodes of stalling after stopping for a little bit. Won't run worth a chit until it is warm and it cools down very, very fast!

No problems like this at sea level.

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

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.

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

Advantage marine, damn I have a selective memory. He raced under Pig Iron Racing. Doug

Thanks for the tip! As to this EFI technology fuel injection, it appears that it simply is a map with no bungs for sensors. All perameters are programed in. Most likely set up very rich even at sea level which makes it very rich at Tahoe.

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,

Phaff said that they could send a guy here who could tune my "EFI" brand injection, even said he could install two tunes and a switch to change from one to the other, one for sea level and one for Lake Tahoe. All I would have to do is change the blower pulleys each time I went to a different elevation and flick the switch.

I would go this route. $2000+ sounds cheap compared to the cost of rebuilding damaged motors. Thats not even a months gas bill for most rigs like yours run for 2-3 weekends. Tuned correctly could possibly pay for itself in gas savings, no damage to motors, drivability, headache, downtime,etc. Also if your trying to sale the boat a test ride would not be very impressive like its running now. Just an opinion I am not an expert by no means.

Rick, I doubt that Gordy from Phaff will travel from L.A. to Tahoe and tune your boat for 2 grand. Call Brad, he's been tuning on the lake for years. No travel time so you already saved a bunch. High performance translates into expensive boating. The correct tune is way cheaper than a blown motor. When I boat at Tahoe I try to clean up the idle so I don't embarrass myself more than usual around the docks. I always seem to have a black transom to wipe down,running a bit rich is cheaper than lean. Doug

What a great, huge tip!!! Brad is the real deal up here! Am going to work with him on this.

Thanks!

That's excellent you have a local tuner there. It might be worth a call to Keith at DynoJet Research and see if you could use a pair of their CMD piggy back units. It's a really clean, proven setup that will give you complete control of the fuel management and has a self tuning feature as well. A pair of those with WBO2's is cheaper then the software licence and cable from EFI Tech. Leaves the door open for future engine upgrades as well.

http://www.dynojetcmd.com/cmd_marine.aspx

Thanks for the kind words HaxbySpeed. Rick, as quite a few have touched on, if you turn the boost up, you will be forcing more air in the motors, similar to what they had at sea level with your current setup. Once you get into the right part of the fuel map, it should be good. The thing is, at those elevations, your ambient pressure is way down from sea level (100-105kPa at sea level, but only about 80kPa at 6000'). If the tune isn't setup to handle this, it will run rich anytime you're not in boost (idle, part throttle cruise before you get into boost).

The Dynojet CMD Marine setup that HaxbySpeed was referring to is a piggy-back system that plugs into the fuel injectors and EFI harness to intercept the existing EFI's firing events. When the stock ECU says "turn on the injector for this long" to deliver fuel, our system reads that time and either shortens it or lengthens it to get the fuel delivery you want. It also taps into the MAP sensor so that your fuel table reference is MAP vs. RPM. While there are other options to the system, the most basic scenario is likely what someone in your position would use.

The key to tuning is to know what the air/fuel ratio is doing. To know this, you will need to install a wideband O2 sensor monitor. We also offer a kit that does this, and will send that data to the CMD Marine unit. You simply need to set the "target A/F table" to tell our unit what air/fuel ratio you wish it to run at in each area of the fuel curve. As you drive, it will tune the air/fuel ratio in "closed-loop" operation, looking at the actual air/fuel ratio, comparing it to the target and creating a "trim" to the fuel delivery. It's really that simple.

As HaxbySpeed mentioned, this system is pretty cost effective. At $599 per engine for the CMD Marine system, and $249 for the wideband setup (per engine), you can have all the ability to tune your engines yourself (or let your favorite tuner do it) for a reasonable price. If you're tight on the budget, you could choose to install the wideband on one engine, let it get tuned in, then move it to the other engine for tuning rather than installing two separate wideband setups. It all depends on what you want to do.

Take a look at our website (http://www.dynojetcmd.com/cmd_marine.aspx), or feel free to contact us at [email protected] for further information. If we can help, we'll certainly do what we can to get you going.

Good luck with your project!

I thought it was 3% power loss for every 1000 ft rise in elevation. This would mean I have lost ~19% per motor, or 170 HP per motor - 340 HP!!!

They actually didn't give me a number, that is what Honker Cut said they would charge me so it was a guess on my part

HaxbySpeed and dynoJetResearch, thank you for your advice! You have to love OSO...! I have forwarded this off to Brad Johnson and my guy in town.

New news, took compression check because one engine had more soot on back of boat than other engine, and only around one exhaust pipe. Did compression check and two cyclinders down... One was 90 the other 85. Did a leakdown test and it's not the valves.... Put a scope in and saw damage to cylinder walls. We think this was caused by disintergrated impellors when it came out of 18 months storage and overheated when son first purchased the boat and test drove it at Honker Cut Marine. Compression test taken pre purchased showed 110 PSI. Have put on 7 hours since...

Engine is already half out of boat for rebuild!

Going to do this right, then going to break engine in at Folsom Lake all day, maybe two days, then going to Lake Havasu boat show and Desert Storm!!!

How do you install an O2 sensor on a wet exhaust???

From my own personal testing of automobiles on chassis dynos, it's more like 4-5% per 1000'. But just my own observations.

Nice! We've decided not to be a vendor at the Havasu Boat Show this year, but I'm thinking about walking it one day...probably Saturday. I will also be at Desert Storm (on vacation). :)

Depends on the systems you have, but most likely you will have to have bungs welded in. CMI's for instance, have tailpipes that can be removed separately from the risers or manifolds/headers, and CMI will cut through the water jacket, drill the hole and weld the bung on the inside, then recover the water jacket to the outside of the bung for $150. Lightning headers offers this for their headers too, but only when first purchasing them. What do you have on your engines?

loose up to 5% per 1000 ft elevation..... Good lord, that's what, 470 HP? This has to be dealt with...!

Doug, are you the same person whom I spoke with regarding going boating on the Sac when I had my 31 warlock SXT?

yes

I have a lot of break in hours to put in - in about 4 weeks. Want to join me?

Rick, I could join you but why don't you consider dynoing the motor. Great way to check for oil leaks before it's buried in a bilge and the motor is broke in and tuned at the same time. Keep in touch. We have a group that starts every year at the Lake Havasua Desert Storm run. Doug

I will mention it to brad, he is taking the project over.