whats a safe high compression to run on a 4cyl?

[4G64T]

im curently building a motor for my turbo setup but while im doing that i want to give a lil pep to the motor i have now so i was thinking about gettin high comp pistons and a new camshaft, springs and retainers i already have the fuel mods because of the nitrous im running. so i was thinking could i get away with 10.5:1 or even 11:1 and on a sidenote has anybody upgraded to a b&m torque converter cuz the level 10 ones are garbage?

im curently building a motor for my turbo setup but while im doing that i want to give a lil pep to the motor i have now so i was thinking about gettin high comp pistons and a new camshaft, springs and retainers i already have the fuel mods because of the nitrous im running. so i was thinking could i get away with 10.5:1 or even 11:1 and on a sidenote has anybody upgraded to a b&m torque converter cuz the level 10 ones are garbage?
if you have the time and the money you can safely boost a 10.5:1 comp motor. People do it on Hondas all the time. However, if you plan on spraying and boosting, I can gurantee that compression is too high. The two main things you need to worry about are air charge temperature and proper fuel delivery. How much boost? How big of a shot of nitrous? 11:1 is really getting up there, you'd already be pushing it with 10.5:1. With 10.5:1 you'd only really be able to boost 5 or 6 lbs without some SERIOUS tuning.

[8ggalant]

1badrs over on the eclipse boards has a gs with 10-1 comp, sleeved block , whole bottom end built with a stock head (no cams or valvework done) and he put out 316 (w/ a big t3/t4) or so and maxed out the cam...so if u plan on "building" the motor set a goal 1st...cuz the higher the comp the more stress on the engine parts...but anyway like scootin said 10-1 is possible ive seen 1badrs' car in person

[4G64T]

although that was very good info you guys misunderstood im not going to be boosting this engine i already have another engine i am working on for the turbo. what i was talking about was doing a high comp motor with just nitrous the turbo is a whole different thing

[Jet Black]

Dammit change you avatar (or tell me what videos shes in), I had to reread your first post like 10 times.

As for Level 10, I've heard a lot of crap about their bulletproofed autotrans. I dont know about the torque converters though.

[4G64T]

hahahaha shes not in a video those are webcam pics she sent me but lately i havent talked to her :cry:

[8ggalant]

<div class='quotetop'>QUOTE(4G64T)</div><div class='quotemain'>although that was very good info you guys misunderstood im not going to be boosting this engine i already have another engine i am working on for the turbo. what i was talking about was doing a high comp motor with just nitrous the turbo is a whole different thing</div>

u positive she sent that to u ...cuz ive seen that on quite a few boards...she musst get around...hahahaha https://www.thegalantcenter.org/style_emoticons/default/laugh.gif j/k

[4G64T]

hey dont ruin a mans dream lol

[akiraflux]

yah he used talked to her...for $20/month! https://www.thegalantcenter.org/style_emoticons/default/laugh.gif

[4G64T]

why is it when a man talks dirty to a woman its sexual harassment but when a women talks dirty to a man its $5.95/min?

[4G64T]

i'll post a couple pics of my ex's so you guys can see what out here in the bay :twisted:

[Elwenil]

Ok, most of my high compression engine experience has been with Mopar V8's with cast iron heads, so this my or may not make any sense to you. Here are a few things that will let you "get by" with higher cylinder compression. One is the octane of the fuel you are running. I know that's a simple one, but I've found that with anything over 11.5 to 1, a half and half mix of pump gas and racing fuel won't cut it. Another thing is timing and ignition power. I was able to run premium pump gas in my 72 Charger's 360 Magnum engine with 11 to 1 compression, because I had a MSD 6AL and I retarted the timing. This cut my power output (according to Mopar Performance) from 440 HP with race fuel, to about 390 HP on pump gas and retarded timing. All any of this really does is tries to control the heat inside the combustion camber. Too much compression, without enough octane and you get burnt exhaust valves and then melted pistons and blown head gaskets. Aluminum heads also conduct heat away from the chamber better than cast iron, so you can get away with about a half a point more. This really doesn't mean much, as the I4 comes with an aluminum head stock. I only mention it for general info. Basically you have to have enough octane, fire from your ignition, and the right parts to make a street engine live with higher compression levels. If the engine runs lean on the fuel/air mixture, you generate more heat and can damage the engine, so you must supply enough fuel. In my opinion, forged pistons are a must, but since you are going to run NOS, I guess you will be running them anyway. I'd also run any engine running NOS frequently a little rich. This is just a little cheap insurance against a lean condition. Oh, and you may be tempted by someone at sometime to use Hyperutectic pistons in a high compression engine, or with light NOS usage. Tell them to stuff it. I've had 5 engines with Keith Black Hyperutectic pistons and only two have made it so far, the third 360 Magnum in my Charger and the 383 in my half ton 4X4, which runs 7.5 to 1 compression. It will damn near run on lamp oil, but it's for rock climbing, and sometimes good gas is hard to find in the boonies. This is just for info, as I actually have no idea what cylinder pressures a 4G63 or 4G64 will withstand. I would agree that you can safely get 10 to 1 to work, and maybe 10.5 with heavy duty rods and a racing crankshaft. You can do what I did and retard your timing to drive around on pump gas and then reset it if you go to the track and can get race fuel, but you better know a lot about your particular engine, as it took me a while to get the right combination to get my 360 to live on pump gas and then make more HP when I wanted it to race. Just my thoughts...

And damn good thoughts they are.

You mention octane a lot...however 95 premium is about the best most of us can go without spending $4.50 or more a gallon for C16. Because of this limited availability, most daily driven boosted cars need to worry more about the temperature of the intake charge.
Basic Charge Coolers:
1. Intercooler: Make sure it's a really damn nice one. My personal favorite is a GReddy type-31. Not too small, so it cools of very well. Not too big, so you don't lose too much throttle response.
2. Start your system off with a cooler intake charge. Instead of just sticking a filter on the compressor housing of you turbo and calling it a day, basically allowing the turbo to suck in already uber-hot air, run 2 feet or so of piping to stick the filter on the opposite side of the engine bay of the intercooler.
Advanced Charge Coolers:
1. Intercooler sprayer can be used to lower intake temps dramatically. A Cry02 system can be used as an intercooler sprayer, intake air cooler, and fuel cooler all at once, for phenomenal power gains.
2. Nitrous Spray Intercooler kits have a cooling effect as well, but I would go with the Cry02 kit, because it is developed by DEI, one of the best manufacturers of temp-control pieces around.
3. Air-to-Water Intercoolers, set up correctly, can yield incredibly efficiency numbers, and under race conditions can even push efficiency numbers above 100%...that is it cools the air charge to BELOW ambient air temperatures.
"Expert" cooler
1. Water/Alchohol injection kits are used to DRASTICALLY reduce intake air temps, allowing for several extra pounds of boost when activated. These are difficult to mess with, but are well well well worth it when used properly.

Fuel delivery is also a major issue. Lean mixtures are most likely to knock, due to the overabundance of oxygen in the cylinders. One of the most basic ways to reduce turbo "problems" is to make sure you have enough fuel getting in the cylinders. In fact, this is ESSENTIAL.