Stupid mechanics thread

I'm considering turboing my 04 spec v and was curious about the effects of it on a NA bone stock engine. Will it affect the reliability of car, gas mileage etc.
 
Ok so i finally got home and can put this post in a way that will be on topic...

Lemme explain why just slapping on a turbo is a "stupid mechanic" move.

Speaking in a general engine sense, when engines are made, of course aspiration is in the formula. So motors that are supercharged, turbo'd, injected, carbureted etc, are all built differently internally in consideration of their respected aspirations. A naturally aspirated engine needs higher compression to achieve the ultimate performance. As to where a supercharged or turbo'd engine needs to have lower compression to compensate for the enormous amount of air being suck through the intake.

Horsepower is measured in laymens terms, by how much air and fuel you can suck into the engine, process those elements, and get them out of the motor. Or more technically called CFM. So thus the more air and fuel you can force into the motor, burn it, use it, and get it out of the engine, the more power you will make.

So being that the internet is full of theories of engine performance, and those mechanics that know just enough about cars to get them in trouble, realize that if they slap a turbo on their engine, they are going to make monster power. This is true to a point, but most of the time hinders the engine or worse causing major engine failure. And here is why...

Going back to the beginning of my lesson, remember when i said all motors are built considering aspiration? Well here is what happens. You take a nissan SE-R that has roughly 175hp and 190 lbs of compression. Just by bolting on a turbo (which is a lot harder than just bolt things on to work right) you drastically increase the compression (or in laymens terms air) into the engine. Boosting compression up to lets say 225hp and now 13:1 or 225lbs of compression. Well to properly get every advantage of the turbo you just put on, well now you need more fuel to use that air, to use that extra fuel you need more spark to burn all that extra fuel.

But wait, it gets better...

The pistons that came with the engine aren't not only not strong enough, but the compression is now way to high and you are at HUGE risk on throwing a connecting rod out the side of the block. We need to get better stronger pistons to hold this thing together. The cylinder head is now trying to push through all that new amounts of fuel and air. So your actually choking your motor and it cant process all that air and fuel (or CFM) thus making less power than you should be making. I could go on and on about the domino effect doing something that stupid really does, but im hoping you get the idea.

If you want to play with that SE-R, have a plan. What do you use the car for? Racing? Cruising? To and from work? Daily driver, weekend drag racer? Whatever. And make an engine around that.

Im guessing you use the car as a daily driver. So ripping the engine apart and spending $1000's is prolly not what you want. But at the same time, you want a little "pep in your step". You don't want to sacrifice reliability for performance. But there are some things you can do.

Start with exhaust. A nice header and cat back system (preferably one that isn't totally obnoxious sounding) will do a lot for you. I don't mean some fancy muffler with a coffee can tip. Im taking headers nice pipes that open it up high flow cats and some mean sounding muffler.

Next start with suspension. Lower it. Get the alignment right. Give it some negative camber and toe it in 1/8 of an inch in the front (google it if you don't understand) get that car to act right for you. You be surprised how much fun it makes a car to drive when it handles good.

Then get into engine stuff. Most horsepower of any performance engine, is in the cylinder head. Look into porting and polishing. .5mm oversize valves, titanium retainers and springs and some lumpy cams. Doing this will require some fuel injector, intake (air and fuel), and ignition work.

Then there will come a day when you are ready to make the nissan a full on race car and we can start playing with turbos and stuff. Well you will have the foundation already to get every piece of horsepower out of what you are doing.

I cant tell you how many morons start by building a car backwards. Specially cars they need to drive everyday. Spend a fuck ton of money on parts only to have blown up their engine the second they start it. Starting by messing with aspiration without considering what comes with that, is just completely bone headed. Think of it this way, you cant put a ferrari engine, in a geo metro with out some kind of major modification. So start with a plan. Build your car around your plan starting with the foundation. Get the frame of the car ready for the engine you want to build. Make sure when you add all that power and speed, that your car can handle going 140mph and breaking to 0 in 100ft. Make sure if you're gonna make a left turn at 100mph, that your car will do that without taking out and old lady and a telephone pole. Then get your motor right.
 
Thanks for a very informative post hard. Yes its my daily driver so reliability is first and foremost and I've already did exhaust w/ nice nismo cat back. Just purchased a stillen header and installing tomorrow.

Only reason I'm considering a turbo is I found a extremely good deal on a nice threadstone turbo. With it being such a good deal I prolly buy it and do alittle research into what components need upgraded to support the turbo. Then maybe I attempt the install.

Speaking of p&p of head and plenum do you do that at your shop? If so I might can send some business your way.
 
You must log in or register to reply here.
Back
Top