High Compression + Low Boost: Your Thoughts
TECH Enthusiast
Joined: May 2008
Posts: 537
Likes: 1
I am puzzled why you would drop $6 to $7K (or a lot more) on a FI set up yet only want to run 4 to 5 lbs of boost. You can equal this performance easily with nitrous for a fraction of the cost. You could always add the FI after next rebuild.
If you really want a FI set-up and don't want to suffer the pain pay someone to install the heads and put it behind you. Lower compression opens more options for a pump gas car - something you really need if you put a lot of miles on a car.
If you really want a FI set-up and don't want to suffer the pain pay someone to install the heads and put it behind you. Lower compression opens more options for a pump gas car - something you really need if you put a lot of miles on a car.
I need to find someone to swap heads with. I have 62cc afr 205 heads if anyone would like to swap for 225 as casts. lol
Current setup.... NA for now
408 lq4, afr 205's 62cc, 8cc dished, dragonslayer crank, .053 gm-mls.... roughly 11.1-11.3cr.
Going FI would be a savings project for sure in opposed to spraying it like it was built for. I am not totally convinced that i want to fill bottles as much as i would use it. Or spray as much as i should for this motor to shine in my 3800 raceweight pig. I am contemplating switching heads and dropping the compression and start saving for a FI setup of sorts. I like the idea of always having power and not flipping a switch or "refueling". Obviously my issue is CR first so i figure that would be my initial step. Buy new heads and sell the afr's or trade. 700rwhp in the vert would make for a fun street car.
How much boost could i get away with on 93octane with say 10.2CR? I could probably achieve that if i step up to a 72cc head. Are the pistons i have now okay for boosted apps? Sorry for newbie questions. Wondering how ideal this switch could be.
Current setup.... NA for now
408 lq4, afr 205's 62cc, 8cc dished, dragonslayer crank, .053 gm-mls.... roughly 11.1-11.3cr.
Going FI would be a savings project for sure in opposed to spraying it like it was built for. I am not totally convinced that i want to fill bottles as much as i would use it. Or spray as much as i should for this motor to shine in my 3800 raceweight pig. I am contemplating switching heads and dropping the compression and start saving for a FI setup of sorts. I like the idea of always having power and not flipping a switch or "refueling". Obviously my issue is CR first so i figure that would be my initial step. Buy new heads and sell the afr's or trade. 700rwhp in the vert would make for a fun street car.
How much boost could i get away with on 93octane with say 10.2CR? I could probably achieve that if i step up to a 72cc head. Are the pistons i have now okay for boosted apps? Sorry for newbie questions. Wondering how ideal this switch could be.
Last edited by 00Camary; Jun 8, 2010 at 11:53 AM.
Im interested as well bc i have a 408 that is around 11.3:1 and am thinking about doing a procharger kit but if compression wont allow me to at least get 600 plus out of it i might just spray it. I was wanting tot run 6-8 lbs and if compression was ok could i run 6-8 lbs of boost and spray a 100 shot would that cause any issues?
TECH Addict
Joined: Aug 2004
Posts: 2,866
Likes: 4
I'm running 12-14lbs on a 404 with 11:1 compression. 14* of timing and a twin nozzle snow meth kit. My IAT's are in the LOW 80's on a very hot day with no knock at all. And like everyone else has stated, it is very responsive. And pulls like a freight train. I think high comp and boost is the way of the future with all of todays technology! Next time I have a motor built I will probably try to get it around 10.5ish tho. No less than 10:1...
To give an example VA speed recently stated in a thread that they run 'enough comp. to make you think 'how the **** is this enigne holding together at 40psi'' or something along those lines.......
also, and yes i know this is on a 2.0ltr four pot and running meth/nitromethane (!!!!), but these guys are running 18:1 comp on their race engines!!!!
http://forums.evolutionm.net/evo-dyn...rd-2007-a.html
The other advantage of running higher comp. is for any given cylinder presure (and thus power) you need less boost. soo instead of needing say 30psi you only need 20psi. This reduces the stress on the turbo and thus the stress on the engine (lower EGTs, etc). that should enable you to make MORE power...... also once you start pushing a turbo past a point (totally dependent on each turbo) you start to loose effincey. this agian means less power evne though you might be running more boost presure. you need to balence the turbo size/design with the engine combo you are running. but as heigher comp. engine will need to run less boost you will not be nneeding to push the turbo to such high presure levles. This isn't a problem on the LS platform at the moment (!!!) but maybe in the future!
But hey what do i know?....Not a lot. lol
thanks,
Chris.
Im with you on this one mate! The theory behind it is a higher com. engine is that they are more efficent. basically you are using the air/fuel in the cylinders better. Now in the past this was a problem as the tuning wasn't that great and with the higher cyclinder presures you increase the likelyhood of dept. but now people are lurning how to tune these engines with BIG boost i think comp. will slow creap up.
To give an example VA speed recently stated in a thread that they run 'enough comp. to make you think 'how the **** is this enigne holding together at 40psi'' or something along those lines.......
also, and yes i know this is on a 2.0ltr four pot and running meth/nitromethane (!!!!), but these guys are running 18:1 comp on their race engines!!!!
http://forums.evolutionm.net/evo-dyn...rd-2007-a.html
The other advantage of running higher comp. is for any given cylinder presure (and thus power) you need less boost. soo instead of needing say 30psi you only need 20psi. This reduces the stress on the turbo and thus the stress on the engine (lower EGTs, etc). that should enable you to make MORE power...... also once you start pushing a turbo past a point (totally dependent on each turbo) you start to loose effincey. this agian means less power evne though you might be running more boost presure. you need to balence the turbo size/design with the engine combo you are running. but as heigher comp. engine will need to run less boost you will not be nneeding to push the turbo to such high presure levles. This isn't a problem on the LS platform at the moment (!!!) but maybe in the future!
But hey what do i know?....Not a lot. lol
thanks,
Chris.
To give an example VA speed recently stated in a thread that they run 'enough comp. to make you think 'how the **** is this enigne holding together at 40psi'' or something along those lines.......
also, and yes i know this is on a 2.0ltr four pot and running meth/nitromethane (!!!!), but these guys are running 18:1 comp on their race engines!!!!
http://forums.evolutionm.net/evo-dyn...rd-2007-a.html
The other advantage of running higher comp. is for any given cylinder presure (and thus power) you need less boost. soo instead of needing say 30psi you only need 20psi. This reduces the stress on the turbo and thus the stress on the engine (lower EGTs, etc). that should enable you to make MORE power...... also once you start pushing a turbo past a point (totally dependent on each turbo) you start to loose effincey. this agian means less power evne though you might be running more boost presure. you need to balence the turbo size/design with the engine combo you are running. but as heigher comp. engine will need to run less boost you will not be nneeding to push the turbo to such high presure levles. This isn't a problem on the LS platform at the moment (!!!) but maybe in the future!
But hey what do i know?....Not a lot. lol
thanks,
Chris.
With that being said you took a standard LS setup and tried to run high boost levels it would lift the heads/stretch the fasteners and push water/leak combustion. Adding larger and more head studs helps the problem but you still dont have a cylinder head that is as strong as the DOHC heads. Speaking with guys that I know in the import world that are at the top of the food chain, they all have no hesistation to running high compression and insane boost levels. We're talking about 12-14:1 on gas and 50# of boost+, these cars make between 550 and 600hp per liter which if all worked out on an LS1 is 3100hp out of a 346" motor. As we push the envelope on engine development we're finding ways to make these motors live at extreme conditions that years ago was just a dream. The problem isn't making the horsepower, its using it.
o-ringing the heads or fire-ringing the block, whatever its called in the V8 world is where its going to be in the future. "camaroandreas" on here was the first guy i ever saw actually use this setup and go figure hes making 1300whp with no issues. I used to o-ring all my blocks with my turbo 4 bangers, never had a problem. After all my success with the 4 bangers, I will get my iron block O-ringed for sure, no questions asked.
Also, i used to run 10.5:1 CR on my turbo 4 bangers. Trying to spool a 67mm on a four cylinder isnt exactly easy. but when it finally comes on, let me tell you!!! haha
Also, i used to run 10.5:1 CR on my turbo 4 bangers. Trying to spool a 67mm on a four cylinder isnt exactly easy. but when it finally comes on, let me tell you!!! haha
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Verdad Gallardo TECH Addict
Joined: Aug 2004
Posts: 2,866
Likes: 4
We are running a ton of compression and a ton of boost on C16. The biggest problem with the LS1s is the cylinder heads/sealing. The imports have an advantage with the double over head cam cylinder heads design as they are significantly stronger than our heads due to the design and sheer mass.
With that being said you took a standard LS setup and tried to run high boost levels it would lift the heads/stretch the fasteners and push water/leak combustion. Adding larger and more head studs helps the problem but you still dont have a cylinder head that is as strong as the DOHC heads. Speaking with guys that I know in the import world that are at the top of the food chain, they all have no hesistation to running high compression and insane boost levels. We're talking about 12-14:1 on gas and 50# of boost+, these cars make between 550 and 600hp per liter which if all worked out on an LS1 is 3100hp out of a 346" motor. As we push the envelope on engine development we're finding ways to make these motors live at extreme conditions that years ago was just a dream. The problem isn't making the horsepower, its using it.
With that being said you took a standard LS setup and tried to run high boost levels it would lift the heads/stretch the fasteners and push water/leak combustion. Adding larger and more head studs helps the problem but you still dont have a cylinder head that is as strong as the DOHC heads. Speaking with guys that I know in the import world that are at the top of the food chain, they all have no hesistation to running high compression and insane boost levels. We're talking about 12-14:1 on gas and 50# of boost+, these cars make between 550 and 600hp per liter which if all worked out on an LS1 is 3100hp out of a 346" motor. As we push the envelope on engine development we're finding ways to make these motors live at extreme conditions that years ago was just a dream. The problem isn't making the horsepower, its using it.
Read this thread, the last few pages seem to get pretty damn cool
http://www.yellowbullet.com/forum/sh...d.php?t=307824
http://www.yellowbullet.com/forum/sh...d.php?t=307824
