Turbo reality check, for god sakes read sumthing useful Options

[playr158]

With all the threads flying around the board about turbo kits and turbo upgrades, many of you are probably chomping at the bit to get that 10lb/rwhp daily driver you've been wanting for so long. If you'll read the fine print on most of the results, you'll see that behind them there is a lot of work and tuning coming into play. The idea that you can take a stock MR2 and turn it into a 300rwhp daily driver by dropping in a $800 upgraded turbo or a $2000+ mid-range kit is completely stillborn. Let's review the fundamentals:

An internal combustion engine makes power by pumping air. The amount of power made is proportional to how much air flows through the engine. Additionally, when the engine is pumping a lot of air and producing a lot of power, about 1/11th to 1/12th of the volume of the mixture going through the engine needs to be fuel. If the amount of fuel is less, then the engine will produce enough heat to melt itself. If it is more then much potential power is lost. Also, the temperature of the air entering the engine and of the cylinder accepting the air-fuel mixture must be low enough to prevent the mixture from uncontrollably exploding before the precise time at which the air-fuel mixture must be slowly burned so that peak cylinder pressures occur precisely 12-14 degrees after top dead center.

On the stock 3SGTE, the CT26 turbine is intended to provide fast response and keep the torque coming at stock power levels. This means about 150-175 ft/lbs of torque out to 7K RPMS. This is accomplished by "sequeezing the thumb over the end of the hose" to increase the velocity at which exhaust flows out of the engine and hits the turbine blades. This gets the blades spinning quickly at first, but as the need for flow increases because the engine is pumping faster and faster, the "thumb" prevents enough exhaust from getting out of the engine to sustain the flow needed to maintain torque to redline. The other supporting systems: the compressor, exhaust, engine management, intercooler, cams and fuel system are adequate for keeping up with the stock turbo setup. If the turbo is upgraded or replaced so that it can produce the 250-275 ft/lbs of torque all the way to 7K RPMS as needed to make a solid 300rwhp, all these systems need to be upgraded. That means planning and money.

Even then, I've seen some impressive levels of power made in a single dyno pull from MR2s that have had very few things upgraded on them. Keep in mind that when you talk about a daily driver, you probably are going to make the equivalent of at least two hard pulls a day, ten hard pulls a week, 50 weeks a year and you are only going to afford to do that on what the local gas pumps are dispensing. That is 500 dyno pulls every year and, for younger drivers, probably more like 1000 on pump gas. Any overweight, beer drinking smoker can run a hard 10 meter race and live--very few of them would survive a hard 10K race.

Almost all the 3SGTE engines that I've tuned that blew up either on the dyno or afterwards were at the 300rwhp mark. In every case they lacked a critical component which was very much required to make that level of power safely day-in and day-out. In all cases the owner had spent serious sums of money getting to that point, but on closer examination it was insufficient or poorly invested.

So what's my point? Don't get too caught up in focusing on one component over all others. A properly built and executed setup will make any capable turbo shine. Don't get lured by the siren call of easy power which, like easy money, never comes but at a cost.


credit: rickyb mr2oc

[Supersprynt]

Not anything groundbreaking - but def. something that people looking into modifying their cars for the first time should read. Power has many components make sure they're all done adequately.

[Sev408]

so i can put a gt40r turbo on my 3s swap and boost at 20 psi on stock internals. WTF dan. I know i dont need fuel for it, cause it already supplies enough. Maybe a Greddy 3 row will help.

[celicast3sgte]

nevermind

This post has been edited by celicast3sgte: Feb 16, 2006 - 5:27 AM

[jgreening]

LOL. I love this thread. Dan if you would just use other people's material more often, we would all get more out of your posts.

This post has been edited by jgreening: Feb 16, 2006 - 6:04 AM

[playr158]

mwahahaha rickyb = my hero

[x_itchy_b_x]

i dont get it? is this supposed to be new? jk jk