| High Compression? - Click HERE for Original Thread |
| Markgase2000 |
What would be considered high compression for a N/A engine?
I forgot to ask - I want know whats considered high compression from small 4cylinder to big v8's. |
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| 2003specv |
| I think on any N/A street engine 10.5:1 is considered somewhat high. You can run higher obviously, but you'd run into detonation much easier. |
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| Markgase2000 |
| Thanks :) ummmmm forgive me for asking , detonation = premature combustion? |
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| PraxRX7 |
| yes, in the case of your piston engine, if the piston is still in the mid part of the stroke, and your fuel detonates, your going to throw a piston out of your engine and bend all the connector rods and such. :blink: |
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| Markgase2000 |
| Whats an easy way to increase the compression or decrease the compression? How and why does it apply differently to different engine setups? I would like to increase my compression and amp up the fuel system but I dont want it to ram my heads. |
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| Praylewd powr |
This could start a "detonation versus preignition" debate and people will be talking about flame fronts, etc.
Here are some definitions: From J and S safeguards:
Preignition and detonation are two separate and distinct events. It was first pointed out as far back as 1906 that the two phenomena were not only quite distinct but were in fact not related to each other. In the first place, preignition in itself does not produce an audible "knock" and if it is audible at all it could be described as a "dull thud". Because preignition is frequently brought about as a result of persistent detonation, the distinct "knock or ping" of the latter came quite erroneously to be associated with it.
It is by no means uncommon for preignition, or in this case it would be more correct to describe it as autoignition, to occur at the same phase as the timed spark. In this case the ignition can be switched off, and the engine could continue to run perfectly steadily without the slightest observable change in performance, sound, or any other characteristic. The danger, however, lies in the fact that all control of timing can be lost and ignition may creep in earlier in the cycle.
The danger of preignition lies not so much in the development of high pressures but rather in the very great increase in heat flow to the piston and cylinder walls when the ignition occurs too early in the cycle. This increase in heat flow, in turn, raises still further the temperature of the hot spot or surface which is causing the preignition resulting in even earlier ignition. At some point the temperatures are elevated to the point where the incoming charge is ignited, causing backfiring in the inlet tract. The belief, still widely held, that preignition can give rise to dangerously high cylinder pressures is totally false. Under no circumstances is the peak pressure resulting from preignition appreciably higher than from a spark-initiated ignition and, in both cases, the peak is reached when the maximum pressure is attained at or just after top dead center, that is to say, about 10 degrees earlier than the normal optimum. As the time of ignition is further advanced by either advancing the time of the spark or by earlier preignition, the maximum cylinder pressure falls again due to the excessive heat loss, for the piston is then compressing gas at or about its maximum temperature, and the intensity of heat flow is increased many times. The danger lies not in the production of excessive pressures but of excessive heat fow. The intense heat flow in the affected cylinder can result in piston seizure followed by the breaking-up of the piston with catastrophic results to the whole engine.
In nine cases out of ten, preignition is initiated by overheating of the sparkplug electrodes or some sharp point or edge that has gone "critical". We are accustomed these days to focus all our attention on the subject of detonation for it is the limiting factor controlling the performance of a spark-ignition engine. We are apt to forget that the real danger is that it leads on to preignition. In itself, detonation is not dangerous... It is the preignition it gives rise to that can so easily wreck an engine. |
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| mwdguy |
quote:
Originally posted by Markgase2000
Whats an easy way to increase the compression or decrease the compression? How and why does it apply differently to different engine setups? I would like to increase my compression and amp up the fuel system but I dont want it to ram my heads.
domed pistons = higher compression
dished = less.
different head gaskets will change your comp a bit as well |
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| 2003specv |
quote:
Originally posted by Markgase2000
Whats an easy way to increase the compression or decrease the compression? How and why does it apply differently to different engine setups? I would like to increase my compression and amp up the fuel system but I dont want it to ram my heads.
We all know it's easy to lower comp ratio by using a thicker headgasket. To go higher, in most cases you can't run a thinner gasket. So easiest way is to mill the heads if you have the valve/piston clearance. This makes the combustion chamber smaller.
Smaller combustion chamber=higher compression ratio (if everything else is kept the same) |
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| mwdguy |
quote:
Originally posted by 2003specv
We all know it's easy to raise comp ratio by using a thicker headgasket.
think about that for a second |
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| 2003specv |
| Yeah I know. Fixed. |
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| Markgase2000 |
| Ok all of this info is helpful thanks :) much apretiated. Now I gotta take it in. Would it be better to lowwer compression for a turbo application? I never messed with turbos and I need to know what kinda setup will work reliably for me. |
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| Nightstalker |
Hows abouts you look at someone that knows how to make high output from a small motor.. ITR (B18c5) 10.8:1 compression.. STOCK.. S2000 (F20c) 11.7:1...
If your not making at least 100hp/l without it being FI or them funny triangles.. perhalps its time to go back to engine design school and figure out what your doing wrong.. Sadly this would mean every domestic car company.. But who am I to judge. |
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| ChromeDragon |
quote:
Originally posted by Markgase2000
Ok all of this info is helpful thanks :) much apretiated. Now I gotta take it in. Would it be better to lowwer compression for a turbo application? I never messed with turbos and I need to know what kinda setup will work reliably for me.
Lower compression is how a typical turbo system works. The turbo effectively raises the compression ratio by providing more than 100% volumetric efficiency (the boost pushes more fuel and air in than possible without boost). If your engine can hold it it's very possible to boost an N/A engine with proper tuning. I know of one particular boosted 300zx N/A engine running 15psi of boost and making some huge hp numbers. If you want to find out some more about engine basics just let me know. I still have some NAIT textbooks that you could take a look through if you like.
quote:
Originally posted by Nightstalker
Hows abouts you look at someone that knows how to make high output from a small motor.. ITR (B18c5) 10.8:1 compression.. STOCK.. S2000 (F20c) 11.7:1...
If your not making at least 100hp/l without it being FI or them funny triangles.. perhalps its time to go back to engine design school and figure out what your doing wrong.. Sadly this would mean every domestic car company.. But who am I to judge.
What about the torque that those engines make Mike? Why do these things always have to turn into fights?
North American manufacturers can build huge power engines, but they build engines for the slough water we have for regular gas over here. Being able to run their economy cars on that fuel saves people money, which is why most buy a domestic in the first place. |
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| mwdguy |
quote:
Originally posted by ChromeDragon
What about the torque that those engines make Mike? Why do these things always have to turn into fights?
4) Please be respectful of other members and moderators.
Excessive flaming and personal attacks will not be tolerated.
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| 2003specv |
Also keep in mind how much stress squeezing over 100hp/litre generates.
If you have a 1.5 and a 2.5 litre engine, and both make 200hp, which one will be less stressed? Which one will (in 99% of cases) make more torque?
Not trying to get into a flame war. I know high reving Hondas are built to take it blah blah blah...... It's just another perspective to look at it from. |
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| shorti |
quote:
Originally posted by ChromeDragon
North American manufacturers can build huge power engines, but they build engines for the slough water we have for regular gas over here. Being able to run their economy cars on that fuel saves people money, which is why most buy a domestic in the first place. [/B]
people buy domestics because the cars themselves are cheap (cheap parts), not because of its gas milage. |
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| DowntownFocus |
quote:
Originally posted by shorti
people buy domestics because the cars themselves are cheap (cheap parts), not because of its gas milage.
This is partly true, some domestic cars are cheeper. I work in a shop and 60+ percent of domestic parts are more expensive than a import part, this is a major missconception when people consider buying Japanise cars such as toyota honda. My cars front rotors are 120 each and it is a aboslute pig on gas.
On to the topic there is a pair of Black EG Civics that have LS/Vetc swaps that run 12.5/1 comp and have run very strong and reliable with 91 pump gas. They have been on the Edmonton streets for about 3 years. |
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| Markgase2000 |
| I dunno about gas mileage I can get 34 mpg with my tempo and I have done alot better with the GA . I am not really worried about mileage or nothin like that just different ways to increase compression without f'ing up my engine. I also wanted to ask what can this do to my engine if I say go for a rip in the mountains? |
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| oldraven |
Your best bet is domed pistons. It's a lot cheaper and easier to do than planing the head. If you want to go turbo, about 8.0:1 or 8.5:1 is a good range for decent boost levels.
Best bet, search the net for someone else who has built a Grand Am Motor, and see how they did it. Every engine is different. |
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| midnite |
| my rsx is 11:1, the s2000 comes with 11.1:1. i wouldn't go higher or you will have to run better than 91 octane. |
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| notaturbotalon |
| 6bolt DSMs come with 7.8:1 and they love the boost, 9:1 is becoming more common for builups now, tune it right and there won't be any problems. |
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| Kris |
quote:
Originally posted by oldraven
Your best bet is domed pistons. It's a lot cheaper and easier to do than planing the head. If you want to go turbo, about 8.0:1 or 8.5:1 is a good range for decent boost levels.
Best bet, search the net for someone else who has built a Grand Am Motor, and see how they did it. Every engine is different.
I wouldn't go as low as 8.0:1 if you are going to go turbo. Go with at least 8.5:1 to 9.0:1. |
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| scooby_dooby |
I don't know about grand ams but on a honda anything under 11:0 is considered fairly reasonable, 11-12 is pretty high, and anything over 12 is considered quite high, but still manageable,
I know guys running 12.5 on 93octane,
To raise it you're either looking at swapping in new pistons($$$) or using a thinner headgasket, but that will only raise it a little, or you can mill your head which raises the CR but retards your timing meaning you will want adjustable cam gears, you can only gain so much with milling as well.
To seriously raise your CR you have to swap in new pistons.
As long as it's tuned safely, your injectors and fuel pump can supply enough fuel, and you are running the appropriate octane gas then you shouldn't have any problems.
When considering raising your CR, you might want to take a look at the relationship between CR and the Duration/Lift of your cams, raise your CR to high and you're engine will be undercammed, blunting the top-end power |
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| oldraven |
quote:
Originally posted by Kris
I wouldn't go as low as 8.0:1 if you are going to go turbo. Go with at least 8.5:1 to 9.0:1.
Well, mine runs 8.3:1 stock, and it boost extremelly well. That's where I got the sub 8.5 from. But again, like I said, every engine is different. |
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| notaturbotalon |
| My bikes at 12.5:1 makes more power than most hondas and premium isn't required, just thought I'd throw that in, was shocked when I read that in the owners manual. But the best bet would be to go with a formula that has proven itself. |
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| ae1969 |
quote:
Originally posted by notaturbotalon
My bikes at 12.5:1 makes more power than most hondas and premium isn't required, just thought I'd throw that in, was shocked when I read that in the owners manual. But the best bet would be to go with a formula that has proven itself.
Smaller bores generally tolerate higher compression much better. One of Hondas "secrets" on running high compression. The other is the combustion chamber configuration. |
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| scooby_dooby |
quote:
Originally posted by oldraven
Well, mine runs 8.3:1 stock, and it boost extremelly well. That's where I got the sub 8.5 from. But again, like I said, every engine is different.
Integra LS's are 9.2 stock and are nearly perfect for boosting, I guess it all depends on the specific motor. |
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| oldraven |
quote:
Originally posted by scooby_dooby
Integra LS's are 9.2 stock and are nearly perfect for boosting, I guess it all depends on the specific motor.
Going off your post and the one before, perhaps it has to do with bore. 2.3L at 8.3:1 may take 15psi+ like a 1.8L at 9.2:1. (I don't know exactly what size the Integra LS displacement is, so I'm going to guess the ever popular B18 honda) |
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| scooby_dooby |
| yup, a mighty 450ml in each cylinder!! |
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| wrxtasy |
I can't find it right now but for Higher boost applications > 1 bar I thought the sweet spot was around 8-8.5:1.
100hp \ L is impressive for a normally asperated engine.. Not so much for a turbo engine.
If the stock motor is a turbo block and pistons you are better off spending your cash on turbo \ fuel system upgrades. If you are going to start doing engine internals it is my opion that bottom end strength is way more importand than mucking with the Compression ratio. |
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| Pro Drag |
quote:
Originally posted by wrxtasy
I can't find it right now but for Higher boost applications > 1 bar I thought the sweet spot was around 8-8.5:1.
It is all in the tuning. If you just want to strap a turbo kit on and settle for "good enough" drop your compression into the basement and enjoy the boost, because that is all that will be enjoyable. Off boost driveability is going to get kicked hard in the nuts. |
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| LeadSled |
Exactly... 8-8.5 :1 is common on older, lower tech engines. Its more common now to go 8.5 - 9.0 for way better off boost power. A friend has a brand new LS2 block sitting at Pro Stock ( or maybe Campbell ) and its going to be turboed in the 8.5 - 9 range.
Domed pistons aren't the proper way to do it either because most really kill the quench effect.... flat tops and milling the heads allows for better quench in most engines and that allows you to run more compression safely (at least in V8s)
Mark, if you want more power you are probably way better off with a turbo/SC kit from the aftermarket than trying to make a high compression N/A setup in your GASE . |
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| Pro Drag |
quote:
Originally posted by LeadSled
Domed pistons aren't the proper way to do it either because most really kill the quench effect.... flat tops and milling the heads allows for better quench in most engines and that allows you to run more compression safely (at least in V8s)
It's all about the squish.:bthumbup: |
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| Markgase2000 |
cool Im gonna consider a turbo , my compression is 9.5:1 right now and I use Regular 87 so would I have to lowwer the compression?
I wouldnt mind a small turbo but I know nothing about varieties and what they are made to do. I dont want to spend an arm and a leg either and it will require fabrication. Any suggestions guys? They have turbo kits available in the states but not here in canada and they are an arm and a leg.
I dunno can you guys help me look into this stuff? |
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| Kris |
| I know of people running high boost on 10.0:1 xompression. That is with a built engine, can your engine handle the extra pressure? |
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| LeadSled |
9.5:1 is not too bad. I imagine 6-8 psi would not be a problem, but its best to do the research and find out for sure. How much $$$ are the kits available? Have any links?
The kit I am looking at uses two GT3067R's, and they're worth $1250 each, so be prepared to pay a few thousand as the bare minimum. |
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| Praylewd powr |
There are alot of Honda-Tech guys just loving 9.5:1 CR but it all depends on the tuning. And Hondas don't break right?
:p |
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| mwdguy |
| i have 10.5/1 comp running around 8lbs right now no problems |
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| Ron@Revolution |
quote:
Originally posted by Markgase2000
cool Im gonna consider a turbo , my compression is 9.5:1 right now and I use Regular 87 so would I have to lowwer the compression?
I wouldnt mind a small turbo but I know nothing about varieties and what they are made to do. I dont want to spend an arm and a leg either and it will require fabrication. Any suggestions guys? They have turbo kits available in the states but not here in canada and they are an arm and a leg.
I dunno can you guys help me look into this stuff?
Switch to 91 Octane atleast! |
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| Pro Drag |
quote:
Originally posted by Markgase2000
cool Im gonna consider a turbo , my compression is 9.5:1 right now and I use Regular 87 so would I have to lowwer the compression?
I wouldnt mind a small turbo but I know nothing about varieties and what they are made to do. I dont want to spend an arm and a leg either and it will require fabrication. Any suggestions guys? They have turbo kits available in the states but not here in canada and they are an arm and a leg.
I dunno can you guys help me look into this stuff?
To combat detonation you can do a few things, increase octane of fuel, lower compression, pull back timing, or lower the charged air temp.
I can look into turbo kits for your ride if you PM me all the stats you have on your car and set some goals for yourself. |
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| Markgase2000 |
quote:
Originally posted by Ron@Revolution
Switch to 91 Octane atleast!
My car runs better on 87 , 91 makes it quirky. Trust me I tried that before. |
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| Markgase2000 |
quote:
Originally posted by Pro Drag
To combat detonation you can do a few things, increase octane of fuel, lower compression, pull back timing, or lower the charged air temp.
I can look into turbo kits for your ride if you PM me all the stats you have on your car and set some goals for yourself.
OK Ill get on this thanks alot for the time :)
This is what I was really interested in doing but ya right lol
http://files.automotiveforums.com/gallery/watermark.php?file=/500/116855Monster_LT1_in_ga_gt-med.jpg
It might be big so dont get mad ok. |
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| scooby_dooby |
Have you researched how well your engine will stand the test of time with a turbo strapped on?
Maybe goto the GA forums and see what they're doing, and what the limits of the stock block/transmission/axles/fuel supply/ignition are |
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| Ron@Revolution |
quote:
Originally posted by Markgase2000
My car runs better on 87 , 91 makes it quirky. Trust me I tried that before.
Not once you put a turbo on it, it won't! I well let you learn the hard way if you would like, just trying to help you out!:dunno: There is no thing as to much Octane on a turbo car unless you can't turn either your timming or boost up any more! |
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| LeadSled |
Christ... a supercharged LT1 in a Grand Am :eek:
The work to convert it to rear drive alone would be crazy... I say go for it ;) |
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| Markgase2000 |
quote:
Originally posted by Ron@Revolution
Not once you put a turbo on it, it won't! I well let you learn the hard way if you would like, just trying to help you out!:dunno: There is no thing as to much Octane on a turbo car unless you can't turn either your timming or boost up any more!
Well Im sure I will be using premium once I have a turbo , I thought you meant right now. Sorry bud :) |
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| Markgase2000 |
quote:
Originally posted by LeadSled
Christ... a supercharged LT1 in a Grand Am :eek:
The work to convert it to rear drive alone would be crazy... I say go for it ;)
Turn a J body into a F body help me sled lets do this ;) it would sure beat using a dinky turbo. Plus the cool thing is Its a 350 lt1 much easier engine to play with than my LA1. But I looked into the cost and it would be in the range of $12,000 - $30,000 bucks to fabricate it. |
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| Nightstalker |
Sell the GA and buy a car with a tuning base behind it. Realistically, the cars that have a lot of parts for them.. Have that for a reason. The ones that don't... .well.... Don't for a reason..
I know that you have put a lot of work into that car, but there is a point were you will likley realize its not worth paying for fabrication of one off parts, for a car that will never be fast. |
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| arabian_ryda |
| ive never heard or seen a boosted grand am before. dont know why but it would certainly be different and quite interesting to see the outcome of one. i think if the motor in the grand am can handle the boost and you have the funds u should go for it. it would be a nice change from the regular cars we always see being boosted. good luck with the decision. :bthumbup: |
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| Markgase2000 |
Thanks ryda thats actually encouraging :) nightstalker just dont like my Grand Ma is all but thats ok he is entitled to his opinion.
I dont mind learning about this stuff but its gonna take time and effort. This tough car has been through everything and has impressed me with reliabillity so it in my opinion well deserves to rip alot harder.
Its been a fun car to learn EFI stuff on so why not learn more of what it can and cannot do since I am so familliar with it now. I dont have too much knowledge of engines but I know my engine pretty good I do 90% of my own labour on it and when I have trouble I always have a technition to give me a hand. I do 100% maintenance stuff on my own as well. So why not learn how to maintain it with a turbo fabrication?
As for the LA1 207ci V6 able to handle boost? Well they got a supercharger kit for them set for the stock LA1 boosting hp too 240hp. What you guys think?
http://www.pfyc.com/store/merchant....ry_Code=GAUNDER
What I dont get is ,,,,,,,,, where is the pulley and belt on that pic ^^^^? |
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| LeadSled |
It would be on the passenger side, out of the pic where all the accessories are. They would use a remote pulley and a shaft that goes to the supercharger to drive it.
Looks like a nice, quality setup. And the nice thing about centrifugals like the Vortech is that they are usually easier to turn the boost up on than Roots.
RSM has a lot of products for GM vehicles so they'd probably have headers, CAI, throttle bodies etc for your 3.4L if you don't want to go crazy just yet. |
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| Nightstalker |
| I don't have a problem with your car man. Everyone can chose there own project. It just seems like a lot of work to me for the kind of returns I would expect you to get out of it. |
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| Markgase2000 |
quote:
Originally posted by Nightstalker
I don't have a problem with your car man. Everyone can chose there own project. It just seems like a lot of work to me for the kind of returns I would expect you to get out of it.
Dont get me wrong bud I respect your opinion it makes sense to me too. I have done many things that took alot of time on this car for small returns and since I did it myself its totally worth it to me :). |
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| Markgase2000 |
quote:
Originally posted by LeadSled
It would be on the passenger side, out of the pic where all the accessories are. They would use a remote pulley and a shaft that goes to the supercharger to drive it.
Looks like a nice, quality setup. And the nice thing about centrifugals like the Vortech is that they are usually easier to turn the boost up on than Roots.
RSM has a lot of products for GM vehicles so they'd probably have headers, CAI, throttle bodies etc for your 3.4L if you don't want to go crazy just yet.
I tried getting my hands on some of this fun stuff but its not really available to ship conventionally to pontiac/gm dealers. So I fabricated my own intakes and porting. |
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| scooby_dooby |
| you need to talk to people who have tried this before so they can tell you the weak points of the engine, and how much boost is safe to run on the stock components, otherwise aren't you just going in blind? You're just gonna choose some random boost setting and hope your bottom end can handle it? |
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| oldraven |
quote:
Originally posted by scooby_dooby
you need to talk to people who have tried this before so they can tell you the weak points of the engine, and how much boost is safe to run on the stock components, otherwise aren't you just going in blind? You're just gonna choose some random boost setting and hope your bottom end can handle it?
That's what I was trying to get at. There's no point in being the Guinnea pig when someone else has already gone through the process. |
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| Markgase2000 |
The boths of yous are right I am gonna be a guinea pig <---sp?
I will keep looking for others who have done this before like you guys suggested thats good advice thanks :) but in the meantime Im just looking into it and gathering your opinions.
Stupid to most of you all but if it worked it would be not only one off but pretty damn unique. My biggest turn off is having something thats just like everyone elses dont take this the wrong way but a tarded movie ahem*fast and stupendous* killed the love I had for the civics for example. Now alls I see is civic tricked out here and civic tricked out there hmmmm every 3rd civic I see is stock! I still think there cool but since Im a unique person (I dont follow the herd) its gotta be one off or else it wont suit me.
Keep giving me input guys it helps alot :). I seen some of your guys rides pics or up close and man oh man I like this club! |
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| oldraven |
Dude, you've got to invest in a dictionary.
http://dictionary.reference.com/
Anyway, I know how you feel. My biggest turn off is having something thats just like everyone elses That's why I drive a T-bird, and not a Mustang or F-body. :) |
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| scooby_dooby |
| have you asked around at the GA forums? You CAN'T be the first person to want to Turbo a grand am, no reason to be the giunea pig if you don't have to. |
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| SilverZ24 |
Davenport in Calgary put a vortech supercharger on a Grand Am for Southpark Pontiac here in Edmonton. I think it was RSM's kit but the install looked very good. Maybe give them a call for some info.
This was about 2-3 years ago though. :) |
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| Markgase2000 |
| Any ideas I have suck! |
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| mwdguy |
quote:
Originally posted by LeadSled
Looks like a nice, quality setup. And the nice thing about centrifugals like the Vortech is that they are usually easier to turn the boost up on than Roots.
hgow do you figure? all they both involve is changing a pulley? |
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| Nightstalker |
quote:
Originally posted by Markgase2000
Any ideas I have suck!
Whats with this post ? And your information ? What happened dude ? |
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