efi tuning at bonneville

[1 fast evo 2]

This question goes out to anyone who has run or helped to tune a forced induction setup at the higher elevations like bonneville.

I would like to get some idea of what you all do with the timing at altitude versus at the lowwer elevations around sea level.
I assume that fuel would need to be pulled due to the lack of oxygen at altitude.
What about timimg ? more/less and why.

This is on a 2 liter 4 cylinder with a big turbo and a liquid to air intercooler in my evo 2.

[hotrod]

How does your engine management system figure out your fuel air mixture. MAF and MAP based systems don't much care about the altitude as they calculate the actual air flow going into the engine and adjust accordingly.

The main difference at altitude is that the turbocharger is operating at a significantly different pressure ratio that it does at the same boost at sea level. If you are using an air to air intercooler its efficiency is down some due to the lower air density and mass flow through the core. Net results of those two changes is that your air charge temperatures will be higher than they would be at sea level running the same boost. Add to that the fact you will be on boost for minutes at a time, start out with a very conservative tune as the long duration at boost will push a bleeding edge tune over the top into detonation or pre-ignition.  In your case with  the liquid to air intercooler you have eliminated one of those issues but compressor efficiency will still be an issue.

Tell everyone a bit more about your setup and perhaps someone can compare your situation with something they have experience with.

Here in Colorado (5800 ft altitude) our air density at 60 deg F is about the same as Bonneville during the meets. You might want to go look at Garrett's catalog and ponder the corrected flow of the turbo. At high altitude the turbo acts like it is moving substantially more air than it really is, and its corrected flow on the compressor map is shifted far to the right on the map. That means if the turbo is not sized properly you will be way outside the sweet spot on the compressor map at speed on the salt.

Tuning wise the engine will like the same AFR on the salt as it would under the same absolute manifold pressure/density at sea level. From what I have seen out there, much better to start safe and work up to an ideal tune than to go even a tiny bit too far and end your event on the first run. I saw a guy melt the top out of a piston, and cremate some valves, on 4G63 in a DSM last year at World of Speed on what he thought was a safe tune on his first run. The engine lived to about the 2.25 mile mark before it went toes up.

Larry

[Dynoroom]

It will help you if you think in terms of "density" and your turbo is your density maker  . I make no changes in my sea level tuneup (on the dyno) vs my Bonneville tuneup. Why because I bring my density with me  . Others like to tune at the vinue I like to sit in the shade and have a cool one. Just call me lazy........

Of course if you change your setup for Bonneville then tuning might be required.

[Rick Byrnes]

Yeah, Mike, until you run out of turbo, then there aint no more.
96" at sea level won't make the same power on the salt.
I think I ran out of turbo every year by being too conservative and not wanting to run out of engine structure first.  Every pass though I just kept screwing the HP knob down and not going any faster.

 

[Dynoroom]

You know what they say Rick, don't bring a knife to a gun fight!   





Besides turbos don't hurt motors......... people hurt motors.......... 

      

[Sumner]

.................. From what I have seen out there, much better to start safe and work up to an ideal tune than to go even a tiny bit too far and end your event on the first run. I saw a guy melt the top out of a piston, and cremate some valves, on 4G63 in a DSM last year at World of Speed on what he thought was a safe tune on his first run. The engine lived to about the 2.25 mile mark before it went toes up............Larry

I try and talk the people that I'm working with into not going for bear on the first run unless the weather looks like it could shut the meet down.  You work for a year on the car/bike what is another 6 hours to play it safe and run hard to say the 3 on the long course on your first run and then come in and look at the data or plugs.  There is more than just the tune that can go wrong and come up and bite you like we found out last year.  Get one run in, get in your rhythm, check everything over and then go after that record,

Sum

[dieselgeek]

This question goes out to anyone who has run or helped to tune a forced induction setup at the higher elevations like bonneville.

I would like to get some idea of what you all do with the timing at altitude versus at the lowwer elevations around sea level.
I assume that fuel would need to be pulled due to the lack of oxygen at altitude.
What about timimg ? more/less and why.

This is on a 2 liter 4 cylinder with a big turbo and a liquid to air intercooler in my evo 2.

I've tuned quite a few 4G63s, not at bonneville, but I currently manage the tune on another turbo car that does race at bonneville.

My honest opinion is that I DO believe there's a bit of difference out there, but not enough to be concerned about given all the OTHER possible factors that can end your week.

My suggestion out at Bonneville is not to "go for broke" on the tune, i.e. don't be runnign the kind of timing that is 1-2 degrees from pushing out a headgasket, because so many other things can be problems - I think it's best to arrive with a conservative tuneup.   What's the record you're up against anyways?  Given your car's build and history so far, I am guessing it might not be too difficult for you to own a record in your class!!   For those that do not know, Mike's little EVO dominated the shootout at the first Maxton event this year, is a solid open roadracing performer, a really nice setup/build with one of my own favorite engines.   1000+ crank horsepower happy on stock crank and block, these Mitsu engines are some of the most undiscovered powerplants out there IMO.


Anyways, I'd suggest arriving with a conservative tuneup and worry about all the other things that can be an issue.  Tech inspection, parts failure and availability, sunburn, you get the idea.

-scott

[1 fast evo 2]

Thanks for all of the advice fellas.
I will definately not be going for broke on my first runs, I usually start out on the soft side and tune towards where I want to be by the end of the race. I don't usually run a very agressive ignition map.

A little back ground on the set-up=
mitsu 4 cyl 2.0 liter built short block with forged pistons-aluminium rods-piston squirters-bla bla bla
worked head-oversized- inconnell exht valves-large cams-yada yada
there is a long tube header on the car with a good sized turbo(74 mm) all of the performance last year was on a 70 mm turbo-liqiud to air intercooler-
The car is tuned with AEM stand alone and is set-up for speed density with boost compensation(NO MAF).
Rite now I have 4 160 lb. injectors and a big electric pump but I am considering swithing to a mechanical fuel pump tobe able to flow more fuel.
The car is allwheel drive and will weigh about 3000-3500 lbs when at bonnevile.
My fabricator Ron Shearer is working on a set-up that we dreamed up and if it works we will not be short of turbo ever again.

The car is drag raced and last year I started doing standing miles with it, it went a best of 215.9 mph at the S.O.R.C. standing mile race last year and won the King of the hill- I also went to the silver state classic last year and won the standing mile at 212.8 mph and the 0 to 200 to 0 comp. and this spring I won the hotrod magazine top speed challange at maxton 210 mph first pass.

If you need any more info just ask.
I was just wanting to know if there was a huge difference in timing at altitude so I don't blow up on the first pass.

P.S.-the record in g/ps is 203.xxx mph

[bvillercr]

Doesn't sound like you need any advice.  Your accomplishments says it all.

[1 fast evo 2]

Thanks bvillercr- but I think it never hurts to ask. The more input I have the less stupid mistakes I can make, as we all know things are going to happen even if everything is as it should be.
I am also very awhere that this is bonneville we are talking about and from what I hear, if it can happen it will happen and if it shouldn't happen it will probably still happen.

[Sumner]

Thanks bvillercr- but I think it never hurts to ask. The more input I have the less stupid mistakes I can make, as we all know things are going to happen even if everything is as it should be.
I am also very awhere that this is bonneville we are talking about and from what I hear, if it can happen it will happen and if it shouldn't happen it will probably still happen.

That is a very impressive car you have put together and with you attitude I'll bet it gets more impressive.  I sure hope I get to see it and see you set a record with it,

Sum

[bvillercr]

Thanks bvillercr- but I think it never hurts to ask. The more input I have the less stupid mistakes I can make, as we all know things are going to happen even if everything is as it should be.
I am also very awhere that this is bonneville we are talking about and from what I hear, if it can happen it will happen and if it shouldn't happen it will probably still happen.

Happens to us everytime we run.  We have had many return record runs only to have something break.  Hopefully this year we will have everything in tune.  Good luck.

[Stan Back]

You know -- the current record holder (I think) is a very impressive car -- with records at both Bonneville and El Mirage over 200.  Maybe I'm not reading the coupe's rite.  But it won't be like shooting fish in a barrel (whatever that means).

[Rex Schimmer]

 1 Fast Evo 2,
You really need to think about the pump size if you decide to go to a mechanical pump. Your present electric pump puts out max volume and pressure as soon as you turn it on, a mechanical pump is dependent on engine speed. If you go mechanical you need to make sure that at any rpm the pump puts out enough flow so that our fuel pressure regulator is working to maintain the operating pressure that your injectors require. Most fuel regulators are pretty crude and don't work well around their minimum open position.  It may be alright at WFO but it may be short on the way up. If you do go with a mechanical pump be sure that you size it for lots of flow because at low rpms it won't be much. I would more consider going to two or even 3 of your present electric pumps and use some over size low pressure electric pumps to provide fuel to them. It probably gets much more complicated from the plumbing and wiring setup than a mechanical.

Let's see if you have 160#/hour injectors and lets say you have a brake specific fuel number of around .6 lbs/hp-hr.(a little fat because it's turbo), then your injectors should be able to flow enough fuel for 1065 hp! That is stout! and probably is why you are going 210+ in the mile. How tight do you wind that thing? You said aluminum rod, I am not a big believer in aluminum rods for sustained rpm. Aluminum has a pretty poor endurance limit which means that the fatigue quickly, anyway much more quickly than steel rods. Can't wait to see you at B'ville in August.

Rex

[ddahlgren]

Mechical pumps work just fine and are a preferred solution for a race car to be honest. They are relativley cheap and trouble free. There is very little to break or wear out at all. With a belt drive pump you can adjust the flow curve vs. rpm to your hearts desire. If the belt drive breaks the engine stops, if one of two or three electric pumps fail the engine melts down. I like situation 1 where the engine stops. With EFI all you need to do is add some cranking fuel to start the engine vs. the electric pump that has full pressure at cranking. Buy a real fuel pressure regulator from Kinsler and you will have no issues ever, theyare around 400 bucks for the real thing vs. 125 for junk...

As far as the timing adjustment for altitude Dynoroom is right on target as would be expected.. You are bringing your own air density with a turbo so what would change other than the air temp depending on how it is intercooled or not. If you don't have a table for ignition vs. air temp and MAP then the engine is not tuned yet. same goes for an NA engine this can all be done on the dyno for the most part. At the end of the day look at the plugs every now and then they have a lot to tell you but becoming a long lost art now. You might have to find a soon to be geezer like me to have had experience doing that before lambda meters and all the things that make life easy.
Dave