Landracing Forum
Tech Information => EFI Questions => Topic started by: 1 fast evo 2 on May 26, 2008, 08:15:09 PM
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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.
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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
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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 8-). 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.
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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.
:-D
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You know what they say Rick, don't bring a knife to a gun fight! :-D
(http://i127.photobucket.com/albums/p126/Dynoroom/3-16-07024.jpg)
(http://i127.photobucket.com/albums/p126/Dynoroom/3-16-07044.jpg)
Besides turbos don't hurt motors......... people hurt motors.......... :evil:
:-D :-D :-D :-D
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.................. 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
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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
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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
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Doesn't sound like you need any advice. Your accomplishments says it all.
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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.
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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
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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. :-D Good luck.
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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).
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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
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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
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Stan back- I know of the galant that holds the record in my class, and have actually talked to the mech./builder of the car but not the owner/driver. The mech. is a very nice guy and really knows what he is doing.
Rex- the mechanical pump I will be running is not just some mech. pump but is a race pump as ddahlgren is speaking of and they make more than enough flow at lowwer rpm than is needed to run the car, he also touched on one of the reasons I want to use it is if it dies the car dies and doesn't nuke the motor.
As for the injectors, the turbo on the car at the maxton race earlier this year would max them out with the current fuel pump setup. The car has already made 930 hp at all 4 wheels very easily, actually so easily I would run at this level at b-ville without thinking twice about it. With the boost cranked on this turbo it should put down at least 1050-1100 awhp which is approx 1200 crank hp.
P.S. at maxton the car was at only about 800 awhp and the pass was no good due to me having to get out of the gas for 2.25 seconds at 200 mph in fifth gear which slowwed the car down to 185 mph and then I reaccellerated up to 210 mph, so she has a bit left in her.
ddahlgren-I am planning to run either the waterman or areomotive pump and I was going to run the large aeromotive rergulator but if you rec. the kinsler I will try that one.
I have a question for you as I know you have alot of experiance, I am doing a drysump set-up and would like to drive the fuel pump off the end of the oil pump but I have heard of people having trouble with the belt drive with it like this, I would like to know if you have seen this alot or maybe not at all, oh ya it will only be a 3 stage pump-1 supply and 2 scavenge.
Oh and about the aluminium rods, I have gone that route this year to help the rod bearings last a little longer also another reason for the dry sump. It seems to have helped quite a bit. Previosly have reved it to 10,000 rpm but this year it will be moved up to 11,000 rpm for drag racing and standing mile races at b-ville I will gear it as tall as possible but will still be at least 9,500 rpm.
I have to run to work,hopefully we can talk more later.
mike reichen
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Mike,
That is one stout piece! Other than the alum. rods what else have you done to the bottom end? With 4WD you should have a real advantage at Bonneville and I want to be there when you get to qualify for the long course by going 175+ on the short course. Should be something to see!!
I would certainly go with Dave D's suggestions as he is a "been there, done that, got the tee shirt" kind of guy and going with the Kinsler regulator is great advice. I have never seen the inside of the Kinsler unit but have seen several of the less expensive ones and was not impressed. I also like the idea of driving the fuel pump from the back of the dry sump pump, I did the design for this type of fuel pump drive for Drake Engineering back in the 80s on a 2.3 Ford banger, it worked quite well but the injection was a Kuglefisher mechanical type and not electronic and we didn't make 1000+hp either!
You think you can keep your foot in it thru the 5 mile???
Rex
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I don't like electric fuel (or water) pumps at Bonneville. I've run Hilborn type pumps for years and would bet you'll see more & more folks making the switch even at the drags in the not to distant future.
Here are a few shots of some record setters.......
(http://i127.photobucket.com/albums/p126/Dynoroom/Morepictures077.jpg)
(http://i127.photobucket.com/albums/p126/Dynoroom/Morepictures642.jpg)
We've even run a mechanical pump like in the first picture with a carb to set the B/GR record a few years ago.
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If there is room on the front drive personally I like a separate fuel pump drive so I can adjust it's drive ratio to suit fuel requirements and the oil pump to suit it's as well. Should they work out the same great run one belt and pulley if not do a separate one. The capacity of the drive power wise far exceeds the demand and a side benifit to both on one is you take a bit of load off of the crank snout and front main bearing as well.
The Kinsler regulator is a work of art and you will never look back and wonder why you bought it. IMHO Aeromotive is consumer grade stuff built for a price and a market. The Kinsler part also goes on IRL cars not built for a price just as good as it can be.
More scavage stages is much better 2 is sort of light duty for the power figures quoted IMHO....
Personally 3 in the pan 1 in the head and 1 for the turbo if it is mounted low in the car. A low pressure oil pan will de aerate the oil and everything lives longer and cooler.
Dave
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Rex-as for the bottom end the mitsus don't need much, it has a stock crank,arias forged pistons(thanks guys),alum rods,o-ringed block,and alot of good machine work.
I don't think it will take til the 5 mile to top it out, I think it will run out of gear.
ddahlgren-let me get this straight, it's better to use 2 drive belts to seperate the oil and fuel curves-I don't have the room at the crank to drive both units but I do have the opportunity to drive the fuel pump off of one of the overhead cams, the only issue with this is it's more cluttered and I will have to plumb in a small electric pump to prime the system to get it started.
As for the dry sump pump and fuel pump what do you rec.-if I drive it off of the cam the bracket is, I believe set up for a waterman pump(are they universal?) I was looking at the R&R dry sump
Do you really think this small engine will need 5 stages ?
The turbo drains into the pan and has a pretty good angle now , if we use the newwer setup it will have even more angle.
I was going to run 1 to the head split into 2 - 1 on either side in the back
and 1 to the pan again split- at this time it is only going to be a modified stock pan
if I run to many stages won't the vacuum become too high.
oh while I am at it do you rec. filling the drains in the head so the pump can scavange it properly and keep the crank case seperate from the head.
What if any ventilation do you need?
Sorry for all the question but I have never set-up one of these things before and it would help alot if you guys can point me in the right direction as it would really save alot of time, I think I already ran out of time to get ready. HAHA
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Mike:
Splitting suction lines doesn't work. Think about it. As soon as one side runs out of oil the other side of the split won't draw. It's much easier to pump (suck) air.
Pete
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O.k so you need a suction line to each side. That brings up another question what happens to the pump when its not pulling oil and it's just pulling a vacuum, I assume it is built to handle this.
Mike Reichen
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There's obviously no problem there as we always use more evacuation capacity than pressure. The only problems I see with the split lines is that oil will tend to build up in one area until there is sufficient to cover the other inlet and I'm not sure but the resulting pulses in the system may add stress to the components such as belts and shafts.
Pete
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not to mention with no oil at one pickup the pump will be sucking air --tried that on my harley and killed the pump willie buchta
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Assuming that the ignition timing was set correctly and if the fuel was the same stuff, the timing will remain the same at elevation. I hesitate to suggest to pull any fuel out of the thing because I also assume that your fuel map is correctly done and the ECU should chase that as well. :lol: IF the fuel changes, then it is a new ballgame. :roll:
The biggest change up here is that the intercoolers (and the radiators) are not as efficient because the density of the atmosphere is much less and the heat transfer does not work as well. :mrgreen:
This message is coming to you from 7200' MSL. :-D
Regards,
HB2 :-)
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I think that, as simple as it is, that's the answer!
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If there is no room on the front though assuming a RWD car not a FWD where the crank is aimed at the frame.. then back of the oil pump next best place in my mind. The cam drive is pretty scared territory as I see it.
Dry sump 2 in the pan and one in the head should work fine. I would not bother to plug the oil drains from the head to the block. No 'split lines' ever.... I like to vent the engine to the oil tank with a -12 line and put a breather on the tank, K&N sells some good ones. As far as vaccum goes it is your friend it deairiates the oil. The only thing you have to be careful of is the piston pins getting too dry if you are relying on splash to get oil to them. The same goes for under side of the piston cooling. Does this have squirters aimed at the pistons like a 2jz toyota?? Oh and NO FILTERS ON THE SUCTION SIDE OF THE PUMP!! PRESSURE OR SCAVENGE!! It is better to hurt the pump than starve the engine of oil.... Don't cheap out and have all the scavenge stages get ported internally to 1 -12 line either. Build a manifold so each stage goes into it then a -16 to the large screen type filter(Oberg) from the manifold... then to the tank. Pressure side is from tank botton to suction side of pump out of pressure stage to a large 2 quart oil filter to oil cooler if used though not needed to engine.
As far as intercooler goes I trust it is ice water to air deal so who cares what the altitude is???
Dave
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Dave has made a very good point about the intercooler question. I was thinking about only air to air. :mrgreen: Duh for me! :?
It reminded me of when all the high zoot open wheel crews were cleaving away body panels at the Denver Gran Prix several years ago to try and improve heat removal in our thin air. :roll:
Regards to All,
HB2 :-)
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Ya the intercooler is an ice water to air set-up so if I get the sizing right on the reserve tank for b-ville the intake temps should be under 100* even at bonneville.
ddahlgren- the engine does point at the frame rail as it is an allwheel drive.
where do you take the vent line to the tank from ?-the top front of the valve cover ?
So you think in my set-up that the best place to drive the fuel pump would be off the back of the oil pump ? thats what I thought as long as there won't be any belt problems.
Also yes I have oil squiters in this engine.
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I think I remember you mentioned you race at places other than the salt flats so you know what G forces are predominent in your car best, so wherever there is air and not oil most of the time..LOL.. If in the cam cover be sure to not plug the oil returns to the block or you will need 2 vent lines. Good to hear your have the squirters they add tons of life to the pistons.Something aimed at the valve springs is not a bad idea either if the cams aggessive enough to warrent it. If you do some searches on dry sump stuff there is a prety cool trick I have brought up several times of having about 10 feet of 3/8 steel tubing coiled up in the tank connected to the engine like it is a heater core so you bypass some water into the line in the tank. It works as an oil heater and cooler at the same time as long as you run a thermostat in the engine. I like the isea of running one as the engine warms quickly the oil does as well with this setup and you can minimize run time on a race engine to mostly racing and not warming it up.
Dave
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Dave, thanks for all of this great info you are really helping me out alot with these things I don't know about.