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Engine Specific Info and Questions => IDI Engine => Topic started by: TUFFY on January 30, 2013, 02:14:50 pm
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I am working on a 1.6 for a pulling tractor. What is the best way to lower the compression some? I have not checked how far the pistons are above deck yet. I have a 3 notch head gasket.
If I was to mill the pistons for a .000 deck height with a 3 notch gasket would that be to low? I am using a 1.6 head.
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If you get aftermarket pistons, they usually set down deeper on the wrist pin.
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I wouldn't mill the pistons, they seem to have a specific shape cast into them to direct the combustion a certain way when it comes out of the prechamber.
You could run the thicker head gasket, the three notch one, or even get one machined out of copper.
I have to ask why lower the compression ratio so much though, considering people run these at high boost without lowering the compression, I think it would be fine especially for an engine that isn't going to be used for thousands of miles. Excessive sustained EGT heat is what kills these, for 10 second bursts it would probably do OK.
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I'm curious to see how the pulling tractor plays out. It's not too far removed from my 1.5L land speed engine. If you have a target value for compression ratio, it's fairly straightforward to figure out how much to remove from the piston top, or how thick of a HG will be needed.
Are you aiming for a specific CR?
Steve.
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Nothing specific, Just looking at keeping the head gasket in it at high boost.
So say when I check piston popout it comes out where it would call for a 1 notch gasket, How much would it drop compression with a 3 notch gasket?
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Why not use head studs and an aaz metal headgasket and you will have a higher tolerance for boost and the compression will be a tad lower.
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what turbo do you plan to use?at what pressure?
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Why not use head studs and an aaz metal headgasket and you will have a higher tolerance for boost and the compression will be a tad lower.
Use an entire AAZ head while you are at it, identical to the 1.6 head.. they'd never know ;)
Usually drops CR to like 17.5? or similar.
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The engine I have is mechanical lifters.
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Does it need to be? You can put a hydro head on the mech bottom eh.
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I'm not familiar with this particular engines layout, but have in the past lowered the compression ratio on an IDI by "selectively" unshrouding the inlet and exhaust valves with a drill and selection of grindstones. How much meat does the cylinder head have around the valve area is the question! If you're desperate how about taking out the glowplugs and replacing them with a blank to increase chamber volume!
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The CR I would not worry about. I would worry about the precups. If you stud it and use the AAZ metal HG people have ran plenty of boost and no issues. IIRC zukgod and 53 willy's were right at or over 40 psi and zuk went through many turbos without having a HG issue. If you have fuel to match the boost I would worry more of the precup failing than the head lifting.
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I thought the AAZ gasket won't work on a mechanical engine.
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I ran one 40,000 miles. You just block off the extra port. I used 3/8" teflon joint seal, some used oil cap material. Search for MJF an Audi 80 *same guy* as he was the first one that did it IIRC. My pics are on myspace and I cannot access myspace anymore bc my browser is too old. Works fine. Also if cost isn't an issue measure the gasket size you need and contact this guy. http://www.gasketstogo.com/faq.htm#stock
He will make you whatever. The aaz in a mech valve engine, no sweat. 120.00 each then shipping IIRC. But if you go that route let me know as I may get one and he does deals if you buy multiples. I might get 2 just in case, so if you got one that would be 3 and I think the price goes down to around 100 each plus shipping.
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1588/4=397cc
397/23=17.26cc
Each head gasket notch size=.1mm difference in thickness
76.5/2= 38.25
Pix38.25x38.25x0.2mm=919mm^3
919mm^3=.92cc
17.26cc+.92cc=18.18cc
397cc/18.18cc=21.8:1 compression ratio
Or is my math wrong, the part that seems wrong to me is the compressed volume I though the precups hold more than 17cc themselves
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WHY do you need to lower the compression?
these engines are forgiving, even with 24:1 comp..
just remember, its not the BOOST that kills these engines, its the DRIVE PRESSURE..
if you can keep your drive pressure low, you can boost as much as you want..
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Is drive pressure the pressure in the exhaust manifold before the turbo?
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Yes sir.
Check this truck out, they took it from 170 whp, to 972 whp and like 55 psi of boost on compounds.
I have kept up with the article since they started back in 2007, and one of their huge issues was when they hit a certain spot of power they were having like 125psi manifold pressure!!!!!!!!!!!!!!
What they do is run a huge manifold blow off that is open when WOT so it bleeds some of the manifolds excess, and still allowing the turbos to sustain ~55psi..
Drive pressure killllsss, more than crack.
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I was planning on a pressure gauge in the exhaust manifold. The problem is with a bunch of gauges I probably won't have time to look at them when pulling. Wish I had a engine dyno to dial it in on.
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Hi, My 1.9 head gasket showed up today. Hopefully with this gasket and ARP studs I won't have any gasket problems. Should the block and head be real smooth with this gasket?
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what turbo do you plan to use?at what pressure?
Going to start out with a T3/T4 and hope to be around 40 psi or more. Might end up with two turbos down the road. Don't know if a opened up stock pump with main spring shimmed will be enough fuel to get me there though.
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A 9mm pump will push quite a bit of fuel ;)
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A 9mm pump will push quite a bit of fuel ;)
That sounds promising
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Yes sir.
Check this truck out, they took it from 170 whp, to 972 whp and like 55 psi of boost on compounds.
I have kept up with the article since they started back in 2007, and one of their huge issues was when they hit a certain spot of power they were having like 125psi manifold pressure!!!!!!!!!!!!!!
What they do is run a huge manifold blow off that is open when WOT so it bleeds some of the manifolds excess, and still allowing the turbos to sustain ~55psi..
Drive pressure killllsss, more than crack.
Talking about the old Cummins? Project Rust Bucket?
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Project Rust Bucket! yes, that was the one. An amazing build. Started with 170bhp, ended up with like 927?! And over 22mpg up from 16.
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It is neither IMP or EMP that blows headgaskets, it is PCP. Boost, fuel amount and injection timing are the biggest contributors, not EMP as stated over here.
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Project Rust Bucket! yes, that was the one. An amazing build. Started with 170bhp, ended up with like 927?! And over 22mpg up from 16.
I know the build very well. Was on my main forum asking for opinions before he started.
The reason for the BOV nitrous. With the timing he needed, and the amount of N2O, the BOV blew pressure around the tiny (62mm is small for the Cummins, TINY for 972hp) turbo so it wouldn't explode in a spectacular fashion. No compounds on that truck.
Here are some specs off the top of my head.
Reg Cab Long Bed 1st Gen Dodge
47RH built OD trans
Gearvendors OD making for double OD
3.07 rear axle (was originally a 3 spd non OD auto truck)
5x.025 injectors
14mm H&R
VE Pumped
62/65/14cm turbo
32" rubber
25-27mpg running 65-75mph
Runs around, I believe, 1300rpm @ 55mph with both OD's.
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It is neither IMP or EMP that blows headgaskets, it is PCP. Boost, fuel amount and injection timing are the biggest contributors, not EMP as stated over here.
high drive pressure helps cause high pcp...
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It is neither IMP or EMP that blows headgaskets, it is PCP. Boost, fuel amount and injection timing are the biggest contributors, not EMP as stated over here.
high drive pressure helps cause high pcp...
You are just guessing, and you guessed wrong ;)
For EMP to blow the head gasket EMP would need be in the order of 3000psi+, not going to happen!
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It is neither IMP or EMP that blows headgaskets, it is PCP. Boost, fuel amount and injection timing are the biggest contributors, not EMP as stated over here.
high drive pressure helps cause high pcp...
You are just guessing, and you guessed wrong ;)
For EMP to blow the head gasket EMP would need be in the order of 3000psi+, not going to happen!
so, your telling me that if the engine has 50psi drive pressure, its going to have the EXACT SAME PCP as a n/a with NO drive pressure?
i find that HARD to believe...
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High drive pressure will leave more residual exhaust gas in the chamber, much like EGR, which should result in a lower peak combustion temperature and therefore less peak cylinder pressure according to how I understand (or don't) the combustion event, however, on a diesel engine that has no valve overlap there is going to be high exhaust valve/exhaust port temps due to no cooling air passing through on the non existant valve overlap, the higher the temp and pressure the more heat transfer to the engines head/exhaust valve so things might melt on a bloke if the heat/pressure loads get out of hand. Personally, I would follow the popular engine manufacturers engineers method of getting good engine life when turboing an N.A. engine, lower the compression ratio (there is a mathematical way to work how much lower you should go...but don't ask me for the correct answer, I would just copy off the factory), and fit an egt gauge....yes I know that you won't get time to look at a gauge while trying to control an animal tractor during a run, so why not buy an egt gauge that has an adjustable high temp alarm and hook up the overheat relay on the gauge to a simple water injection setup? Here's a cheap but not nasty gauge that works well: http://www.auberins.com/index.php?main_page=product_info&cPath=5&products_id=139&zenid=1b6cf09cc9e005f44cef75787b6a1210 You have to put the probes cost on top of this, so around $100. from memory gets you cheap engine insurance!
EDIT: here's a link to the probe: http://www.auberins.com/index.php?main_page=product_info&cPath=5_22&products_id=69
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http://youtu.be/2ylbJj8X6lk
Here is a video from across the big pond of a tractor with a 1.3 VW diesel. In line bosch pump and a cross flow head.
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How does one steer these things when the front wheels are in the air for much of the time? 2 brake pedals?
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Posi-Trac ;)
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We steer with rear brakes, posi rear ends will find the out of bounds lines in a hurry most of the time unless you run a ton of weight on the front so you can steer it.
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http://youtu.be/auzPlVRtEK8
A VW TDI they claim about 500 hp and turns about 9000 rpm. Punched out to a 2.0 liter.
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Figured the brakes too. interesting thread :)
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Loooka that thing just clear it up and haul some ass once the boost picks up eh!?
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http://youtu.be/NamlOEMJBnw
Same tractor warming up. It takes lots of either until there is some heat in the motor.
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Thats gotta be tough on the starter motor, almost 10 minutes to fire it up! I'm wondering if they have tried some pre-heating techniques. I wouldn't want to be breathing all of that smoke as it's a known carcinogen!
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High drive pressure will leave more residual exhaust gas in the chamber, much like EGR, which should result in a lower peak combustion temperature and therefore less peak cylinder pressure according to how I understand (or don't) the combustion event, however, on a diesel engine that has no valve overlap there is going to be high exhaust valve/exhaust port temps due to no cooling air passing through on the non existant valve overlap, the higher the temp and pressure the more heat transfer to the engines head/exhaust valve so things might melt on a bloke if the heat/pressure loads get out of hand. Personally, I would follow the popular engine manufacturers engineers method of getting good engine life when turboing an N.A. engine, lower the compression ratio (there is a mathematical way to work how much lower you should go...but don't ask me for the correct answer, I would just copy off the factory), and fit an egt gauge....yes I know that you won't get time to look at a gauge while trying to control an animal tractor during a run, so why not buy an egt gauge that has an adjustable high temp alarm and hook up the overheat relay on the gauge to a simple water injection setup? Here's a cheap but not nasty gauge that works well: http://www.auberins.com/index.php?main_page=product_info&cPath=5&products_id=139&zenid=1b6cf09cc9e005f44cef75787b6a1210 You have to put the probes cost on top of this, so around $100. from memory gets you cheap engine insurance!
EDIT: here's a link to the probe: http://www.auberins.com/index.php?main_page=product_info&cPath=5_22&products_id=69
I had one of these on my modified 1 cylinder alcohol burning Kohler tractor but the vibration killed it in no time. Its the tractor in my ID picture.
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Thats gotta be tough on the starter motor, almost 10 minutes to fire it up! I'm wondering if they have tried some pre-heating techniques. I wouldn't want to be breathing all of that smoke as it's a known carcinogen!
It was sort of running on its own most of that time, all the white smoke was from when he stopped spraying ether into it and wasn't warm enough to keep going on its own.
There is a video of a big pro stock tractor that takes about 3 cans of ether to get it on the track and backed up to the sled lol. They run really low compression in them to make them live.
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http://youtu.be/4cvMhlWW9R4
Pro stock problems in cold weather,,,
I have heard that some of the pro stocks are running a single turbo in the 4.8 to 5.2 inch range.
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High drive pressure will leave more residual exhaust gas in the chamber, much like EGR, which should result in a lower peak combustion temperature and therefore less peak cylinder pressure according to how I understand (or don't) the combustion event, however, on a diesel engine that has no valve overlap there is going to be high exhaust valve/exhaust port temps due to no cooling air passing through on the non existant valve overlap, the higher the temp and pressure the more heat transfer to the engines head/exhaust valve so things might melt on a bloke if the heat/pressure loads get out of hand. Personally, I would follow the popular engine manufacturers engineers method of getting good engine life when turboing an N.A. engine, lower the compression ratio (there is a mathematical way to work how much lower you should go...but don't ask me for the correct answer, I would just copy off the factory), and fit an egt gauge....yes I know that you won't get time to look at a gauge while trying to control an animal tractor during a run, so why not buy an egt gauge that has an adjustable high temp alarm and hook up the overheat relay on the gauge to a simple water injection setup? Here's a cheap but not nasty gauge that works well: http://www.auberins.com/index.php?main_page=product_info&cPath=5&products_id=139&zenid=1b6cf09cc9e005f44cef75787b6a1210 You have to put the probes cost on top of this, so around $100. from memory gets you cheap engine insurance!
EDIT: here's a link to the probe: http://www.auberins.com/index.php?main_page=product_info&cPath=5_22&products_id=69
I had one of these on my modified 1 cylinder alcohol burning Kohler tractor but the vibration killed it in no time. Its the tractor in my ID picture.
I haven't had a problem with mine, but then my engine is pretty smooth, and the vehicle body is mounted on rubber pads to the chassis too. I suppose you could leave the gauge on an extension wire loom, and drop the gauge into your pocket to minimise vibration if you can't come up with another system!
Have you looked into getting a decompression plate made for your engine? The headgasket could be used as a template, it shouldnt cost too much! EDIT....How much slack is there in the timing belt? If you do fit a decompression plate make sure that the timing belt will still have enough length to fit around the cogs
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so, your telling me that if the engine has 50psi drive pressure, its going to have the EXACT SAME PCP as a n/a with NO drive pressure?
i find that HARD to believe...
Off course PCP will not be the same, but you are dumping a lot more fuel into a TD to get 50psi EMP than what you are doing to an N/A with no EMP ;)
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so, your telling me that if the engine has 50psi drive pressure, its going to have the EXACT SAME PCP as a n/a with NO drive pressure?
i find that HARD to believe...
Off course PCP will not be the same, but you are dumping a lot more fuel into a TD to get 50psi EMP than what you are doing to an N/A with no EMP ;)
im not disagreeing because excessive emp can be caused by a number of things, but wouldn't it be true that if you are running 30 psi boost and have an emp of 60psi (which is quite possible for people running too small of a turbo and way too much fuel) then at tdc when the exhaust valve shuts it is leaving a very hot 60psi in the dead space of the cylinder. the piston will have to travel down 10-20 percent of the way before pressure equalizes and boosted fresh air begins to flow in. but that is just quick math in my head wouldn't that leave a bunch of hot and already burned air in there so on the next xompression stroke everything gets even hotter and the next injection will not have as much o2 so it will burn even hotter make pcp higher and higher.
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Thats gotta be tough on the starter motor, almost 10 minutes to fire it up! I'm wondering if they have tried some pre-heating techniques. I wouldn't want to be breathing all of that smoke as it's a known carcinogen!
It was sort of running on its own most of that time, all the white smoke was from when he stopped spraying ether into it and wasn't warm enough to keep going on its own.
There is a video of a big pro stock tractor that takes about 3 cans of ether to get it on the track and backed up to the sled lol. They run really low compression in them to make them live.
usually around 14:1 compression..
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so, your telling me that if the engine has 50psi drive pressure, its going to have the EXACT SAME PCP as a n/a with NO drive pressure?
i find that HARD to believe...
Off course PCP will not be the same, but you are dumping a lot more fuel into a TD to get 50psi EMP than what you are doing to an N/A with no EMP ;)
im not disagreeing because excessive emp can be caused by a number of things, but wouldn't it be true that if you are running 30 psi boost and have an emp of 60psi (which is quite possible for people running too small of a turbo and way too much fuel) then at tdc when the exhaust valve shuts it is leaving a very hot 60psi in the dead space of the cylinder. the piston will have to travel down 10-20 percent of the way before pressure equalizes and boosted fresh air begins to flow in. but that is just quick math in my head wouldn't that leave a bunch of hot and already burned air in there so on the next xompression stroke everything gets even hotter and the next injection will not have as much o2 so it will burn even hotter make pcp higher and higher.
Good point Trevorbr, so an engineer would be able to work out what effect the residual exhaust gas would have on peak cylinder pressure, probably with the help of all operating parameters - in theory anyway. There are at least 2 ways to look at this scenario, I believe that the factory engineers use egr to lower peak cylinder pressure in order to avoid making too much N.O.X. (pollution), yet residual chamber exhaust gas is going to dilute and heat the charge! One of the newer pollution control devices is cooled egr, I think that the cooler egr allows more power to be made without causing an overheat condition in the engine, I believe that egr is only operated at part throttle conditions too, but I'm not up to speed on pollution control so am just thinking aloud!
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I believe that the factory engineers use egr to lower peak cylinder pressure in order to avoid making too much N.O.X. (pollution), yet residual chamber exhaust gas is going to dilute and heat the charge! One of the newer pollution control devices is cooled egr, I think that the cooler egr allows more power to be made without causing an overheat condition in the engine, I believe that egr is only operated at part throttle conditions too, but I'm not up to speed on pollution control so am just thinking aloud!
EGR reduces the amount of oxygen in the cylinder (exhaust gasses are very low in oxygen since it has mostly already been combusted), thereby reducing the amount of oxygen available to combine with the nitrogen naturally in the atmosphere. It is only used at part "throttle" as during WOT you are trying to use all the displacement available to you, whereas you don't "need" the whole engine's displacement when you are cruising along at 15% max power.
Oxygen and Nitrogen will combine simply in the presence of heat, so yes the EGR cooler helps reduce the temperature and therefore the speed of that reaction. Diesel exhaust also has more leftover oxygen than gassers do making the EGR cooler even more relevant.
On gassers EGR also helps reduce pumping losses since the EGR gasses don't have to be pulled through the throttle, reducing the "work" required to pull the piston down the bore. That doesn't apply to diesels though since we don't have a throttle plate.
All this EGR theory though only applies at part throttle - at WOT you want to get all the spent gasses the hell out of the cylinder. Partly because you need the cylinder to be full of oxygen-rich air for the next burn, but also because the exhaust gasses are HOT and the incoming cold air will cool things down. So when we are talking about high drive pressures we are talking about peak operating power, where temperatures will be the highest and the risk of damage due to high EGTs will be the most prevalent. An increase of 200° due to leftover hot exhaust can definitely make the difference!