Why aren't some concerned about putting a turbo on a high compression motor?

[dave77]

I see people post about getting a turbo or thinking about it, on the stock FA20 engine. But with the high compression of 12.5:1, I don't think it's a good idea. I'm not an expert at all on engines, but this is one of the more common sense things about cars. It just adds pressure to an engine with already high pressure.

[AVodka14]

I agree with having high compression motor with a turbo not being a logical combination. Yet I have also read that the motor was built quite strong. Now, that does not mean one could not burn up a piston or break a rod.

I plan on a turbo in a couple of years. Rods and pistons are getting replaced with the turbo install. Other things can still break. I am most concerned about the transmission and drive shaft. Or burning up the clutch. Compression ratio would be the least of my worries when considering a turbo in this car.

[OmarGC]

Two words.

DIRECT INJECTION

[midnight23]

If you can afford to go FI, you most likely can afford a built block if / when it pops.

[stugray]

That is one reason for all the talk of E85 with FI.
Less chance of knocking at boost.

[SmsAlSuwaidi]

Technology has Gone a long way. Cars now run a 14:1 comp on pump gas, few years ago people bitched about 12.5:1

[Photonic]

Originally Posted by stugray

That is one reason for all the talk of E85 with FI.
Less chance of knocking at boost.

correct. Octane rating for instance has absolutely nothing to do with power by itself. it is a common misconception I hear all the time that "Well 93 is best I get good gas mileage" or "93 is best It feels faster"

I think E85 has an octane rating around 110 +? correct me if I am wrong?

But we all know E85 has less energy per gram than gasolene. So what the hell does it matter?

Octane rating IMO just refers to how much a fluid can be "compressed" before the pressure and heat of said compression causes it to detonate before the timed spark, this results in bad things happening and it is why engines fail more than most usually, tuning problems.

All engines are chunks of metal moving at high speeds..it really isnt rocket science. I am just a third party who hangs around very old guys too often who like to talk too much and write their own ecu's ...and I can never figure out when to leave and go home without interrupting them ...

But compression ratios do not matter as long as you keep in mind where your threshold for spontaneous detonation of your fuel occurs, if you can intercool it, methanol inject it , retard your timing ..w/e.

it doesn't matter ..

The only thing you need to concern yourself with is combustion chamber temperature/ mix temperature as I understand it. Compression ratio and boost pressure and volume are "variables" that affect that, but your only goal is to keep your fuel from spontaneously detonating. There are many ways to do/influence that

and I Would suggest learning more about fuel itself to the OP.

[OmarGC]

You guys are missing the point.

Again, technology has come a VERY long way. Direct injection, gives you the benefit of keeping the cylinders much cooler than a standard fuel injection system. Thus allowing you more headroom for boost, and more aggressive timing and fuel profiles.

[SmsAlSuwaidi]

Originally Posted by OmarGC

You guys are missing the point.

Again, technology has come a VERY long way. Direct injection, gives you the benefit of keeping the cylinders much cooler than a standard fuel injection system. Thus allowing you more headroom for boost, and more aggressive timing and fuel profiles.

You guys know what the compression ratio of a Porsche 911 gt3 is? 12.9:1, boosted properly

Gt3s arnt boosted and gt2(which is boosted ) has a 9.4:1

but yeah i do agree with everything else you wrote
Sent from my IBrick

[Photonic]

Originally Posted by OmarGC

You guys are missing the point.

Again, technology has come a VERY long way. Direct injection, gives you the benefit of keeping the cylinders much cooler than a standard fuel injection system. Thus allowing you more headroom for boost, and more aggressive timing and fuel profiles.

Thats why I said what I did. maybe you posted it before I responded. I am curious to hear you elaborate more on my input. I like your stuff.

I prefer to focus on fundamentals rather than the general idea. if your fundamentals are good ..you can open your head to the kinda stuff you are talking about. I have a lot to learn about direct injection still ..but again all you need to look at is how you can keep your mix cooler ..cooler = less detonation threshold = more compression or timing can be run ...and it = more efficient also.

Thanks so much! I like to make more long winded answers. I can be annoying. but I Want to assume people may not understand where I am coming from. Maybe people don't know what "cool" means in regards to how all the variables come together.

[CSG Mike]

High compression + boost is ideal. The only concern is that the engine can handle it.

High VE + boost =

You guys should do a little research on how much boost a BONE STOCK s2000 engine can take reliably. It's a 11.x:1 compression engine without DI, and is using 20 year old technology now. Hint: It's a lot.

[dave77]

Exactly. I think porsche knows what they're doing when they lower the comp on the gt2 to put the turbos on.

Originally Posted by SmsAlSuwaidi

Gt3s arnt boosted and gt2(which is boosted ) has a 9.4:1

but yeah i do agree with everything else you wrote
Sent from my IBrick

[SmsAlSuwaidi]

Originally Posted by dave77

Exactly. I think porsche knows what they're doing when they lower the comp on the gt2 to put the turbos on.

Turbos on a high comp motor is not as bad as you think


Sent from my IBrick

[dave77]

So I guess the consensus argument for turbo is 1) use E85 gas and 2) direct injection helps cool things.