how to pick turbo pistons, Best compression for boost
Вставка
- Опубліковано 30 сер 2017
- this video is about picking the right compression ratio for boost in a smaller displacement engine. mostly my opinions and what has worked oner the years.
- Авто та транспорт
Compression ratio is a factor of fuel flash point, inlet air temperature, air density , combustion chamber temperature, cylinder volume, volumetric efficiency, thermal dynamics and rpm's. Smaller displacement per cylinder engines will have higher compression ratios as they are compressing a small amount of air and less heat created. Larger displacement will have lower compression for equivalent fuel and rpm because they are compressing a larger volume of air faster, increasing the temperature of the air. This is why turbos often run rich to reduce intake temperature and prevent pre-igniton or knocking. You can run a high compression ratio with a lot of boost as long as you can get the air cold before it reaches the combustion chamber. Engine manufacturers do dry testing of engines and compression ratio where they spin up the engine by an electric motor and monitor how much heat is created. A safety margin is always included in mass produced vehicles for bad quality fuel and hot climate.
Pre ignition and detonation are different. But some of the same results will occur. Pre ignition is normally due to hot spots in the combustion chamber . Normally caused by a bur or carbon build up. Detonation on the other hand can be caused by a few things. Compression ratio/ fuel oct. Combustion chamber design/ piston top design. And so on... higher octane fuels burn slower and have a lower flash point.... i guess in as simple terms as i can lay it out... The air/fuel mixture in your cylinder after the valves slam shut will double its pressure each time it is halved in the cylinder, once your compression stroke has started. Its will also heat up due to the friction of the molecules passing over each other. So if you have a lower octaine fuel with a lower overall volume in your cylinder/Combustion chamber. It is prone to "Detonation " .. this is an un timed auto ignition due the factors explained. Normally it will occur before the piston is over top dead center . This causes it to push back against the piston. Thats when you bent stuff. In a nut shell. The name of the game is to fill that hole with as much air/fuel mixture as possible before the valves slam shut. Then squeeze it until the point of ignition. Then get all the burnt out as your pulling more fresh air/fuel in ( see: scavenging , cam overlap, exhaust pulse timing) . Creating the most force possible on the top of the piston ( see: B.M.E.P break mean effective pressure) . I hope some of this rant helps someone . If anyone would like some more in depth info on these things feel free to ask. I love these vids , but it really is more complicated than people assume. Yes you can make real power with stuff you toss together. But if you are serious about stretching your buck, then its best to not waste it on trial and error.
Awesome! You’re clear and to the point unlike a ton of others... keep it up!
As clear as a muddy glass of water.
One of my earliest vids lol defiantly rambled a bit
@@GearheadsAutofab No worries at all mate. We all start somewhere. Most haters on here talk shit but they wouldn't be able to do any better. Everyone wants a simple answer but the truth is there is no answer. There's too many variables. Most important being what fuel they are using or if meth/water injection is utilized. Also the skills of their tuner and what the end goal is.
If you need the answer go to 6:51 👌🚗💨
Gearheads Autofab 8 or 9:1 can both manage 10psi on pumpgas 1:5 comp is used for 50 psi boost on topfuel dragsters running methanol
@@matthewfredrickmfkrz1934 well, the air to fuel ratio on a top fuel is like 3:1. It runs on nitro and it burns so much of it so fast that it makes upwards of 10,000 HP. FYI, a normally good a/f ratio for a gasoline car is 11-14.7/1. Way less fuel.
@@nickhowell168 a lot of stock CR from before 2000 is 9-10:1 which according to sloppy mechanics YT channel is fine (for GM stuff) guys with the SC 3800 l67 grand prix gtp Bonneville ssei ect will swap in the higher CR NA3800(10:1?) l36 block for what they call "free boost" since the supercharger won't be able to make it past 10psi...5:1 was the magic number for running stupid high boost which sounds like it'd be super fun as a daily driver (sarcasm) sloppy guy does 9s in a Colorado and drives home 3:1 may be the CR within the blower idk I'm still at the uh... What turbo should I use on my fiero... Oh a stock gm supercharger can bolt on the engine I swapped in? stage lol... Got the hptuners and a plan with junkyard parts from America...
Oh it says AF ratio that's stociometry for gasoline 14.7:1 different fuels require more or less of it iirc e85 is 12:1 while hydrogen has a stellar 40:1
@@matthewfredrickmfkrz1934 what does that have to do with my comment?
@@nickhowell168 what part... The 3:1 x 5:1 = 15:1 running CR or the 14.7:1 stociometric a/f for gasoline?
greate stuff mate very well explained all the way from australia
Thanks for the information.
It's helps so much good info
Good, informative vid brother 🤙🏽
If you are going to run loads of boost, and higher compression, you need to go over the pistons and heads chambers, polish everything smooth! Get rid if any sharp points, they cause detonation(of your wallet also) also ceramic coating on valve faces, chambers, and piston domes, help alot reduces hot spots, keeps the oil and water cooler, keeps more heat in the exhaust, making more flow to the turbo, a cooler sparkplug also, just hot enough it doesn't foul when at idle! If you run a thick MLS head gasket, it doesn't hurt if the pistons are out the deck about 0.25mm depending on engine design, and enhanced oil return from the oil ring can make a big difference in performance also, you are basically always going to have some blow-by, if oil can find its way out of the rings, it will more likely stay in the oil pan, out of the cylinder, oil hurts performance! Lowers octane! I wish I had a cnc to work heads!
Thanks good info 👍
Thanks 👌
Hell yea good advice bud
+Thomas Barker thanks
I am running 16.2 to 1 compression and 20 psi of boost. And no spark plugs. It is called a diesel engine.
#alldetonation. Sounds like you need more boost 😂👌🚗💨💨💨
that's pretty low, modern turbo diesel are running 23:1 compression
Herka durka durrr. Just cause it smoke dont mean it broke! Real trucks ain't got spark plugs.... a hurka durka durrrrrr.
Douche.
@@sven7639 that’s why they cold start so well now
k
Normal ignition advance causes the mixture to burn before TDC, the ignition is timed so that the peak pressure occurs after TDC.
Just to throw it out there, 9:1 for street, 10.5:1 for street race, 8.5:1 for daily, but it depends on use, system, engine, and fuel!
JAMES! Since the 70's simple answer 😎👍
This is one of my least clear videos lol. But let me just give you a little food for thought. I agree with James! If you don’t know your engine at all this is a grate general recommendation. However, when I Dyno tune newer import cars that have a compression ratio of 10.0-1or more, lowering the compression on these engines even to 9.0-1 eats up nearly the first 7-10 psi just to get back to baseline horsepower, then A lot of people that are on Chesper Turbos can only go to a maximum of 25 or 30 psi. So if you make 150hp stock +25psi that’s maybe 400hp, now lower it to 9.0-1 that’s 300hp. This is ok, but then when my customer is board of 300......they turn it up all the way and only make 30-50 more........ (this is all first world problems lol , but I see it allot) then that have to buy lots more stuff to go up in Hp, vs keeping the compression.
Don’t follow numerical values. Think of the principles involved.
Good job, check and see if a fuel and air mixture in an engine burns or explodes
Soo I have a 2016 mazda 3i sport, skyactive 2.0l 4cylinder. It has a 13:1 compression ratio and I really want to do a turbo kit install (watched the turbo video you put up) any advice?? I know it is insanely high. It makes about 150hp to the crank stock, and I am looking for around 300. That is nothing too crazy for the compression circumstances right?
thank you
great info. very knowledgeable channel
Good shit
You should do some investigation of the latest Formula 1 engines - they're running at the point where they are merging spark ignition and controlled compression ignition with high compression and boost in engines AND with rule limited fuel flow that have to do ~2000 miles before replacement.
If you have 100psi of compression and 10psi of boost, how much pressure does that add to the cylinder (less losses and efficiency of the intercooler)?
So go with forged and stick to same compression ratio is a good idea
I have a VW UP GTI (stock 115 BHP) and upgrading the turbocharger for a hybrid version and going for a stage 3 custom remap. The stock CR is 10.5 to 1. I am looking at non forged pistons (hyper) and forged rods. Also looking at 102 RON fuel. what would a target BHP be? Thanks
What about if your running straight e85?
This video helped a loy, thanks bro!
And what about the transmission
My car nissan Patrol y61 4.8l
Is there any problem for automatic transmission
if i reach 600 hp
Should talk about fuel. If you are using pump gas using high boost and high compression you can use spark timing and highest octane to solve some of the "knock" (detonation). If you have over boosted your engine you may need to run racing gas. Detonation occurs sooner with lower octane fuel. Octane does not = horse power but high boost may need high octane to work properly.
Nice vid bro, what's ya thoughts on running 10psi on stock Na pistons 10:1 longevity or worth pumping the gasket up, doing on the cheap😉 1.6l 8 valve
With proper tuning you’ll be fine, just as long as the motor is strong enough, I have tuned allot of 10:1 motors to 7-10 psi over the years and the only one that had issues was if the rod was too weak for the tq. Like the 1.5 Honda motor, broke that at 9 psi. But the 1.6 has slighty better rods And lasted good at 10-14 psi.
But probably you will be ok
I have a c20xe red top, any suggestions on the compression ratio?
Compression does cause detonation. The compression pressure ignites fuel. Just like in a Diesel engine. It’s the pressure that ignites the fuel not the glow plug. Glow plugs only warm up the combustion chamber. On a gasoline engine the pressure will ignite one flame front then the spark initiates another flame front and they collide that is detonation,, just like pre ignition. The spark initiates one flame front and then the pressure ignites another and they collide. It’s like hitting your piston with a hammer,
I do not agree with statement about decreasing CR from 10:1 to 8.x:1
I did that, and I had no lag at all, it was super aggressive like on / off switch, ofcourse I am using standalone ecu..
My engine is old opel c20xe 2.0L 16v, CR was 8.4:1 with KKK24-7000 from audi s4 2.2 20vt
I was out of vacuum at about 2500 rpm, got 1.2 bar of boost at 3200, all the way up to 7000rpm, it spins every gear, cannot get tracktion, even on ice with studded race tires..
Well he said dropping the ratio was for efficiency reasons, and he is right about that. By lowering the compression ratio you increase the amount of fuel required to get a detonation of the likes of if that engine had a higher compression ratio. Basically you are wasting more fuel by burning less per stroke and thus requiring more fuel to get the same amount of power. The downside to high compression ratios is that they require a higher octane rating to avoid knocking. Turbo chargers and other forms of forced induction also increase the likelihood of an engine knocking on lower octane fuels, so when in combination with one another, you will likely have to run a higher octane rating than you would stock to prevent yourself from damaging the engine. Although cars with 9:1 compression ratios on their own can run just fine on 87 fuel, a properly tuned turbo charged car with a 9:1 ratio would require 91 at the least. Basically it comes down to finding an amount of money you are willing to spend per week on gas, as higher octane fuels like 91, 93, and E85 are significantly more expensive than "regular" 87 gas, or "super" 88 15% ethanol gas that you'll find at newer gas stations.
Yes yes piston design, im running a dart 347 with a 70mm turbo and am on my second set of pistons because I keep breaking ring lands, the first set were dss and damaged 4 pistons, the second set are wiseco and broke 1 piston, im running 10.4-1 compression and only 10lbs of boost but i don't have a good engine management system, going to try holley terminator x, we'll see
engine management and tuning is key... 10.4 to 1 isn't that high these days I actually run 10.4 to 1 with over 20 lb and tuning is the key...
Sounds like you aren't giving the pistons enough ring gap.
Richard Holdener has many times taken a stock k series or ls v8 and then gap the rings about twice stock. He is making a lot of power with stock block,factory pistons,rods and cranks.
Maybe check out some of his videos.
Hi, thanks for the video. I just had a question about compression/boost/fuel. So on 17psi my car made 245kw atw on 98 fuel on an engine with 10:1 compression. At 24psi, this is now 265kw netting only 20kw gain after adding 7 pounds of boost (generally should expect 7kw per pound depending on application). My question is..why would the gains so low if high compression wasnt an issue?
Conner Goldberg Im no expert but it sounds to me like your turbo is out of its efficiency range
There could be a few things going on here, it could be turbo efficiency if it’s a cheaper turbo or if the turbo sizing is small. But most modern name brand turbos would not be past there range at 24psi. You could look at the hp rating on that turbo see if your making with in 50 of its max potential at the wheels. If the turbo is not maxed out then there is either a restriction usually or a Tuning problem. Make sure the turbo is rated for more hp then make sure your intercooler is not maxed out , make sure you don’t have too small exhaust piping or turbo housing etc. good luck hope you find the lost hp. Oh make sure the clutch isn’t slipping too. 👌🐌🚗💨.
Gearheads Autofab intercooler and 3 inch exhaust top out at 320 to 350kw or so. Turbo is capable of pushing 31psi just not recommended to do on the engine since it is still running on 98 so advancing the timing is causing knock sensor to go off.
Gearheads Autofab the turbo is a gtp762 which have data making 350kw on e85. I will be upgrading the intercooler though.
So many reasons, but head design is usually a common issue. Porting and or valvetrain gear
Cool dude thanks
Nice subject - but no answer. You can run any amount of high compression you are able to control. Amount of heat in charge, hot spots inside the cylinder (that includes pistons to) and fuel are basic limiting factors. So yes, you always want highest possible compression, though in some cases high can be quite low in absolute numbers.
I have a stock 400m and am planning on getting new heads, distributor and intake manifold. The compression ratio is 7:1 if I remember correctly but either way really low. I cannot find forged pistons or any other forged parts so I was wondering would turboing it be safe and improve efficiency?
Not sure what a 400m is, but ya usually turbo is safe if it’s done correctly and kept in a moderate range, there’s always risk because it needs to all be done correctly and the tune needs to be good enough to keep it from getting the motor. 7:1 is really low compared to newer motors but that’s not the only factor to boosting and really only effects the efficiency as a starting point. Your basicly going to increase power over stock everywhere it makes Boost. Hope that helps .....feel free to ask more questions if you need to so that you can make the right decision for your project.
Hey Shane, are you talking mopar 400, if so... Hit me back ill email you some great info, not really turbo related but I've found some great options with pistons
Lower the compression the more air/fuel you can squeeze in there without detonation!
This is like that PC build guide by the verge except with more expensive and catastrophic outcomes! You can't just start talking comp ratio without addressing the primary factor of fuel choice.
so what about the brz at 12.5:1?
What about a 4g15 dohc could that take boost ?????
my question is,
can I increase the compression of 9: 1 to 10: 1 when rebuilding my Porsche 997 Turbo engine
From 2008, the vehicles had 9.8: 1 compression as standard
Not a Porsche expert but if it was my car I would go to 10:1 🚗💨💨👌
Dictionary police: Detonation is a super sonic chemical reaction i.e. trinitrotolene.
Which pistons the best pistons for quality? And which can raise the 3000+hp?
3000 hp? Are you thinking of 300 hp instead
Strongest pistons are usually forged pistons, quality will generally depend on the company making them.
I'm gonna be building a 1.8t 20v BAM and the factory is 8.5:1 I think. The parts I'm getting or what I can get are rated for 8.5:1 so there is no point lowering it and it'll make the 800bhp mark a lot harder to reach😂
My uncle ran dished pistons cos he was running nos. Told me if you dont want to have blown head gaskets and problems dish is better than domed pistons
We get it. You have multiple cameras 😹
Lol omg 🤦♂️
So my S54 has 11.5.1 stock compression im getting the precision 6766 (900+hp) and im about to get some carillo forged piston and connecting rods. I can still stay with stock compression right? What do you suggest me as compression?
I would stay close as posible. If it was my car I would check to see what Comp pistons where available and stay over 10.0.1. I think you’ll loose too much efficiency if you drop it more than a point or so. All the old school dudes will tell you to drop it to like 8.1 lol I heard this for years ......in makes the cars horrible to drive if it’s too low.
@@GearheadsAutofab Thank you for the quick response. they offer 8.5.1 - 9.0.1 -9.5.1 -10.0.1 - 10.5.1 -11.0.1 - 11.5.1 - 12.0.1- 12.5.1 - 13.1. i will not be racing that much just quick fun on summer time and im not looking for full capacity of the turbo kit 900hp. Im looking for around 680-700hp crank so this confusing me on the compression. to go base on efficiency.your page is very instructive by the way
My last car had 10.5-1 and I boosted 55 psi making about 1150hp ish I would guess..... I only dyno it at 38 psi made 950hp. The thing most people won’t tell you is that at sone point turning up the boost is not posible. Trying to get 700 on a street car takes like 30+ psi so that might be all the turbo will do , so if you start with lower compression you’ll need a bigger laggier turbo or more compression........hope this helps!!
Ps my daily is a n54 and my friend panda wants me to turbo his e46 next ........🤘
@@GearheadsAutofab what fuel do you use on that set up?
No mention of higher octane fuels. Drag cars are running high compression and big boost for years in e85 and racegas. No soupbowl low CP piston with boost will make the record times these teams are making at the track.
What about a rb267
9:1 is a good setup for boosted vq37
Ya 9:1 is about the lowest I would go. We just had custom pistons made for our 350z by Aries at 10.0-1 there the hd piston super strong 💪. There’s no good off the shelf pistons there all too low compression. Or too high like 11.5
Any thoughts on the 14:1 in the Mazda askyactiv
What if u had an engine with a 13:1 compression ratio? Where would you start?
What engine?
Race gas
My engine is of cast iron. It has 6:1 stock. Does it mean that I have to lower it to 4.5:1? :D
Oh, but mine is around 7:0 and pulls 60hp of madness...
Lol
d16Y for racing, how much compression is good?
Non turbo I like 11-11.5 , turbo 10 10.5 is good .
Why do they sell 8 to 1 pistons then
A flat top piston has the best burn 👍🏼
ULB SRY bro what pistons should i use for m20b28 turbo
10.2/1
Octane.... Race fuel exists for a reason. Octane numbers mean resistance to pre detonation.. I came here for info on 2 strokes. I get the 4 stroke setup... Maybe I'm overthinking this.
CAN U SHOW HOW TO CHANGE TURBO PISTON IN 125 CC ENGINE ?? CAN U ?? PLEASE BRO
No
It is proportionate to the turbo.
First ask how much boost is being fed into the motor.
Back to where we started from . You didn't even talk about octane
You didn't address cylinder pressure. That, not compression ratio, is what it all boils down to. You can change your cylinder pressure by advancing or retarding the valve opening events, changing the duration and LSA of the cam, among other things. A 9:1 engine with 10 PSI boost may run fine with one cam and self destruct with a different grind. There are so many parts to the puzzle. The simple question of "What compression should I have to run boost?" is very hard, to answer.
I run 14.1 plus 25lbs of boost on methanol 🤷♂️
Wow... how much has changed in 3 years ....it's not unusual at all to run 10: 1 compression on a turbo engine ....a lot of Honda guys are running north of 11: 1 no problem.... running 45 lb of boost(race)....
Ya dude my car was 10.8:1 I ran 55 psi 1200hp aprox, and went 2-3 drag seasons between refreshing motors.
@@GearheadsAutofab nice... damn beast .....🏁
Shave the beard man, for real
Dacht net hetzelfde lol
he is a muslim
9:1 or 12:1
8.0:1 30 psi boost
wrong, 8 to 1 is a great compression ratio for turbo, tons of factory turbo cars were designed that way.
Lol.. doesn't address the question until after 6:51.
Wtf
+Gee Tee ya I should add a time stamp so people can find the needed info 👌
Low compression kills power find the right tuner compression don't matter to much got people running 20 plus on 11.5.1 on 600 plus hp cars shits funny
You simply did not answered the question.....you just kept beating around the bush.
Ya true one of my earliest vids took me 6 min to get to the point. What engine are you building for turbo ?
just run e85
Dont make it hard
Sorry it was one of my earliest vids .....should have made it more clear and easy to understand.
All wrong