highest street compression?

[14.5 drift]

it is mathmatically correct, that if you double the pressure you will double the power, but there are alot, make that, way too many variables, but as long as the turbo is in it's efficiency range, and all things being the same, intake temps, timing, blah blah blah, the numbers will double. sO MANY VARIABLES THAT IT WILL NEVER TURN OUT THIS WAY THOUGH, BUT IN THEORY IT IS TRUE.

:sorry about the caps, but I'm not retypeing it damn it!

 

[Mirage2LTurbo]

I run gas ported pistons on my car, oil consumption isn't anymore than leaks out of your drain line or oil cap.

Lower compression pistons allow you to run more boost on a given fuel than higher c/r pistons on that same fuel. Just because you run double the boost, doesn't mean your compression ratio (c/r) changes. If your head or block is decked, that can affect c/r.

Doubling your boost doesn't mean shit. Learn a bit about turbo dynamics, look it up on google. I don't think howstuffworks.com really touches on the efficiency ranges of turbos much. Also, it's not just the heat of the air that affects power differences between a small turbo and a large turbo. A larger turbo also flows more air at a given psi, so more air = more fuel = more power.

In response to sweet97, I run a 9:1 motor on 29psi currently, planning on mid 30's. Does that mean my motor's going to "grenade"? No, it's all about what octane you run, how much timing you throw in, what a/f, EGT's, etc. You can run 30psi on an 11:1 motor if you want on the street, but plan to pay out the ass for C16.

In response to drift14.5, I'm not quite sure what you're tring to say about fuel and ignition systems being the part that allows you to run higher c/r. That's kinda like saying you can't drive a car without a steering wheel. It's more of a supporting mod, I know tons of daily driven honda's running 12:1 on stock ignition that run fine, they have slightly larger injectors and some fuel control just because they also have maybe cams or headwork done to flow more air. More air = More fuel = More power.

 

[14.5 drift]

In response to drift14.5, I'm not quite sure what you're tring to say about fuel and ignition systems being the part that allows you to run higher c/r. That's kinda like saying you can't drive a car without a steering wheel. It's more of a supporting mod, I know tons of daily driven honda's running 12:1 on stock ignition that run fine, they have slightly larger injectors and some fuel control just because they also have maybe cams or headwork done to flow more air. More air = More fuel = More power.

Thats fine, not many people do get me. I was referring to the aggressive computer and fuel systems that the top fuel, and all out drag cars utilize to run super high boost on super high compression, but I guesss your saying it can be done without all the goodies more power to em.

 

[Mirage2LTurbo]

Thats fine, not many people do get me. I was referring to the aggressive computer and fuel systems that the top fuel, and all out drag cars utilize to run super high boost on super high compression, but I guesss your saying it can be done without all the goodies more power to em.

Top fuel dragsters run computers?

 

[92redman]

Top fuel dragsters run computers?

I was under the impression they could only have computers for logging. I thought they have a type of modified carb setup and a distributor type ignition, unless I am blind...

 

[Mirage2LTurbo]

I was under the impression they could only have computers for logging. I thought they have a type of modified carb setup and a distributor type ignition, unless I am blind...

AFAIK that is how it is..

 

[14.5 drift]

ignition systems.

 

[Black94TSI]

Thats fine, not many people do get me. I was referring to the aggressive computer and fuel systems that the top fuel, and all out drag cars utilize to run super high boost on super high compression, but I guesss your saying it can be done without all the goodies more power to em.

Top fuel cars run in the neighbourhood of 6-7:1 compression.

 

[Mirage2LTurbo]

ignition systems.

Please, don't post when you don't know what you're talking about. Read and learn.

Black94, I didn't know that, nice. I always get off on the 3in fuel lines and the MSD capacitor the size of a garbage can on the side of the car. I wish I could make a pass down the track and "lose a bank," that would just be effin cool.. And still run a mid 5.

 

[Mirage2LTurbo]

it is mathmatically correct, that if you double the pressure you will double the power, but there are alot, make that, way too many variables, but as long as the turbo is in it's efficiency range, and all things being the same, intake temps, timing, blah blah blah, the numbers will double. sO MANY VARIABLES THAT IT WILL NEVER TURN OUT THIS WAY THOUGH, BUT IN THEORY IT IS TRUE.

:sorry about the caps, but I'm not retypeing it damn it!

But it doesn't matter, because it doesn't happen that way. Ever.

 

[Maglin]

Doubling your boost doesn't mean shit. Learn a bit about turbo dynamics, look it up on google. I don't think howstuffworks.com really touches on the efficiency ranges of turbos much. Also, it's not just the heat of the air that affects power differences between a small turbo and a large turbo. A larger turbo also flows more air at a given psi, so more air = more fuel = more power.

Well the reason it is more air at a given pressure is because it is cooler. When air gets hot it expands and thus pressure will rise. Which we all should know from grade school. Are you running the side ported pistons are top ported? I saw some vendor selling a ported piston where the second ring land was getting ported air... Not to sure how that works out but just wondering.

And top fuel running 7-8:1 CR... I dont' think so... I'm not running a TF Dragster or funny car but I can't see 8000 HP as the quench volume is to great and the tendency for know at the greater quench volume rises.. But if you know someone who does for a fact know this then wow is all I can say... I do know some people that where into Drag's 10-15 years ago and they where running duel CDI's, Insain Static CR's are 14-71's... They where not putting down 8000 HP but it was hot for it's era..

Also about computers in Drag's... I don't think they run any computers as the rules I think still state that you can't in TF.. I could be wrong as we are evolving with our technology and Carbs are becoming extinct.. But they where or are using a mechanical fuel injection with a Belt driven fuel pump off the crank and increased fuel pressure with RPM's.... These where off or WOT systems and not very advanced but did the job good for WOT racing.

 

[11secDSM]

What a thread. I feel stupider just by reading it. It seems like everyone is just repeating themselves....and most of what is being said isn't even true. Seriously, before you input your .02 make sure you have the facts. As to what compression you are running...it all depends on what you are looking to get from your car. As for me, I am currently building a 6.5:1 compression motor using venolia pistons and planning on running around 38 PSI with a healthy dose on nitrous. But that's not what everyone should build. If you want a nice street monster...stick to mid 8 range. Like I said...it all depends on what you are looking to get out of your ride.

Not trying to start an argument...just trying to state the facts.

 

[14.5 drift]

But it doesn't matter, because it doesn't happen that way. Ever.

wow, you are quite abbrassive, I don't claim I know it all, so..........yeah. Sorry

 

[sweet97]

I tried stating that high boost required low compressin but was toldhigh boost and cmpression go together si i graciously bowed out. nice to see someone who believes low compression allows high boost!

 

[DSMeclipse4G63]

I tried stating that high boost required low compressin but was toldhigh boost and cmpression go together si i graciously bowed out. nice to see someone who believes low compression allows high boost!

depends on combustion chamber setup....a pent roof combustion chamber can allow boost but will be limited by compression. while a hemispherical combustion chamber can handle alot more compression. so on one hand 30psi needs 7:1 compression while the other can handle 8.5:1 or more and 30psi. look at diesels the new 6.0l deisel runs 18:1 compression, with a minumum spec for boost at a decent 22.5psi. granted they run off the heat of compression/ direct injection...but still its all in how the combustion chamber is setup.

granted the best way to make the most power is run as high compression and as high boost...but gasoline motors dont run off detonation like diesels...so its a kind of balance that is needed.
Andrew

 

[Mirage2LTurbo]

Well the reason it is more air at a given pressure is because it is cooler. When air gets hot it expands and thus pressure will rise. Which we all should know from grade school. Are you running the side ported pistons are top ported? I saw some vendor selling a ported piston where the second ring land was getting ported air... Not to sure how that works out but just wondering.

And top fuel running 7-8:1 CR... I dont' think so... I'm not running a TF Dragster or funny car but I can't see 8000 HP as the quench volume is to great and the tendency for know at the greater quench volume rises.. But if you know someone who does for a fact know this then wow is all I can say... I do know some people that where into Drag's 10-15 years ago and they where running duel CDI's, Insain Static CR's are 14-71's... They where not putting down 8000 HP but it was hot for it's era..

Also about computers in Drag's... I don't think they run any computers as the rules I think still state that you can't in TF.. I could be wrong as we are evolving with our technology and Carbs are becoming extinct.. But they where or are using a mechanical fuel injection with a Belt driven fuel pump off the crank and increased fuel pressure with RPM's.... These where off or WOT systems and not very advanced but did the job good for WOT racing.

Larger turbo's flow more air because they are a larger turbo, yes they blow a cooler charge, but that is not why they flow more air. My ports are inbetweent he first and second ring I believe, been a while since the motor was built.

 

[92redman]

Actually I believe the guy who said Top Fuel is running 6:1 or 7:1 is correct. Here are a few links to help explain:http://www.turbofast.com.au/racefuel5.html http://www.turbofast.com.au/racefuel15.html
Here you will find that for a methanol/nitromethane mixture of around 94% nitro(about what top fuel runs) it is recommended to not exeed 7:1. Now I believe the reason for this is because nitromethane has a tendency to detonate. Detonation is usually caused from too much heat, which in this case would be caused by too much compression. If you look at the fuel characteristics, nitromethane has a cooling effect(latent heat of evap.) nearly half that of methanol. The cooling effect is terrible compared to alcohol so why do they use such high mixtures of nitro? Because over half the weight(about 53%) is oxygen, which means you can burn a lot more oxygen just by using more nitro but you risk blowing the engine up from detonation.

So what does this have to do with the discussion? Only pointing out that for top fuel, the reason they need to run low compression ratios is because adding more and more nitromethane to the mixture is similar to raising the compression ratio for a gasoline burner. So Top Fuel doesn't really follow the same rules as other fuels. I believe with methyl alcohol, it is better to run high compression and high boost to make power since the cooling effect of alcohol exeeds any other race fuel and it is much less less prone to detonate than nitro. Gasoline fits somewhere between the two. It is not really as prone to detonate as nitro, but it will knock because of the lack of cooling. So a moderate compression ratio(i'd say around 9:1) coupled with moderately high boost is best for making power with gas.

This is just my .02 cents. I tried to include as much facts as possible, but if something mentioned is wrong, just point a link to facts.

 

[1fast97gsx]

Either way ... when I started this post I said "STREET" compression ... as in whats the highest you would run in a daily driver. Not an all out race car. Lets just drop all this arguing bs because it isn't really helping the reason this post was started.

 

[autronicDSM]

wow, you are quite abbrassive, I don't claim I know it all, so..........yeah. Sorry

Then why won't you stop posting if you don't know? I had up to here with your posts. I'm suprised nobody said anything to you yet.

 

[sweet97]

9:1 w/forged pistons.

 

[14.5 drift]

Then why won't you stop posting if you don't know? I had up to here with your posts. I'm suprised nobody said anything to you yet.

You could have it up your ass if you prefer, if there are inacuracies in my posts, I will always cop to them, I am not the type to defend missinformation on the premise of protecting my "good name". Frankly I don't really care. There have been other members who seem to have thought the same as me, yet I have been targeted. You can go wag your finger some place else, as some one mentioned, with the use of alcohal high compression and high boost is possible, this would be the aggressive fuel and ignition set up's I was trying to reference earlier, not nitro. I mind my business, I try to keep my posts clean and with out attitude, and when I #### up factually I dont mind being corrected. Every body wins. But when others get there jollies ####ing bashing other members for a simple innacuracy thats when it starts to bug. Your smart, that is cool for you, does that mean you should be allowed to sit on a pedistal? Nevermind, I think I am asking the wrong crowd, any one feel free to speak up if you feel the same................or let me hang on this one, either way, whatever.

 

[Mirage2LTurbo]

You could have it up your ass if you prefer, if there are inacuracies in my posts, I will always cop to them, I am not the type to defend missinformation on the premise of protecting my "good name". Frankly I don't really care. There have been other members who seem to have thought the same as me, yet I have been targeted. You can go wag your finger some place else, as some one mentioned, with the use of alcohal high compression and high boost is possible, this would be the aggressive fuel and ignition set up's I was trying to reference earlier, not nitro. I mind my business, I try to keep my posts clean and with out attitude, and when I #### up factually I dont mind being corrected. Every body wins. But when others get there jollies ####ing bashing other members for a simple innacuracy thats when it starts to bug. Your smart, that is cool for you, does that mean you should be allowed to sit on a pedistal? Nevermind, I think I am asking the wrong crowd, any one feel free to speak up if you feel the same................or let me hang on this one, either way, whatever.

It has nothing to do with us being smarter than you, or targeting you. You have made countless stupid posts in the past, I believe you even defended burldude in one string of posts. Your posts in this thread are completly without base. The guy asked a question, and you start throwing out theory. Theory doesn't mean jack shit. Then you try to defend your post even after told you're wrong. Just stop spreading BS and misinformation. If you *think* you know the answer, go look it up, then come back and post, that way, eveyrone DOES win because you won't see me replying, the guy asking the question gets a good, reliable answer, and you are happy to have helped him.

 

[bastarddsm]

I love it you guys are talking about fuel cars and you don't know dick shit about your own cars. those cars run like 50psi, and they are as close to hydrolocing every time they fire. they almost completely fill combustion chamber with fuel. And yes they are computer controled, in the timing advance and the clutch.

 

[autronicDSM]

You can go wag your finger some place else, as some one mentioned, with the use of alcohal high compression and high boost is possible, this would be the aggressive fuel and ignition set up's I was trying to reference earlier, not nitro.

What the hell are you babbling about? What is aggressive setup? Just stop posting, period. You have absolutely no clue.

 

[Maglin]

My bad.. I was thinknig of alcohol and was Methonole... (sp) I didn't know that Nitro motors ran such low CR's... I'm building my short block atm and am using Weisco 9:1 CR Pistons.. I'll let you know how much boost I can run with my B16G, and at what timing advance... I'm shooting for 20-22 PSI and at least 20 degrees advance... But it's going to be squeed cause now it's sooo cold out here... My IAT is like around 30 F atm and is just going to drop drasticly over the next month so I don't think I'll have a problem until spring shows it great head in 6-7 months... But I'll post what I can get...