Stroked NA

[Nomad707]

umm... that isnt the point, the point is you dont know what the motor is going to be like, and its cheap / logical to do it now.. plus you'd need to change the compression ratio because turbo's dont like high compression.. (you dont NEED to, but it would be smart to do so)

 

[Nick M]

Actually, turbos love high compression. They respond much faster.

 

[Nomad707]

then why do all models of cars that have a turbo option, the turbo has less compression and NA has more??

its easy to raise compression so why didnt they?

 

[jdub]

High compression is good for low end, even on a turbo motor. The problem with increasing piston CR on a turbo motor is the effect it has on dynamic compression when the motor is in boost....it increases...a lot. That makes a turbo motor more prone to detonation at higher boost...not good. It's easier to use lower CR pistons to avoid that and increase top end power using boost.

 

[Nomad707]

thanks for clarifying jdub.. i wasn't quite sure, but i did know there was reasoning behind my claim.

 

[Nick M]

then why do all models of cars that have a turbo option, the turbo has less compression and NA has more??

its easy to raise compression so why didnt they?

It is cheaper to use low compression than a forged piston. A 12:1 engine with, just for the sake of argument, 8 lbs from a T04B, will out power the same engine with compression at 8.5:1, all through the range, without question.

You need better fuel, and more of it; i.e. a good tune.

 

[Nomad707]

oooh.. ok.. so when your running a turbo on high compression without the right tune it will combust prematurely?

 

[Nick M]

oooh.. ok.. so when your running a turbo on high compression without the right tune it will combust prematurely?

The combustion triangle in an automotive application is compression, air/fuel ratio, and ignition timing. But like the natural world, if you have enough heat, you will ignite without an ignition source. Provided the A/F ratio will allow it.

In the late 80's, a Honda race car, I couldn't tell you anymore if it was Formula One, or Indy League Racing, had 16:1 compression and 55 PSI.

 

[figgie]

Probably IRL.

They were running 45 PSI on top of the straight methanol.

F1 was using tolune cut with n-Heptane to reach the octane requirements.

edit: for clarification.

 

[IJ.]

^ That would be really good for your complexion :aigo:

 

[figgie]

^ That would be really good for your complexion :aigo:

well remember, that was before they figured that is was not so nice to your skin, hair, eyes, brains, lungs etc.

They probably would have used straigh benzene but they knew about the nastys in that stuff from a while back!

 

[IJ.]

 

[figgie]

hahahah

Toxic Avenger ownz!

 

[IJ.]

He worked as a refueller in the 80's

 

[Nick M]

Talk about the perfect picture at the perfect time.

 

[Alan]

I asked this question earlier. Well I see that there is alot of work and money to invest in a project like that so I have decided to look for a 2JZ and put that in my car but now here is a new question for you all do I use the factory Mark 4 ecu or do I use a stand alone?

 

[IJ.]

Again personally I'd go standalone

 

[figgie]

Yes

MoTeC unless you want to try something different....

http://www.supramania.com/forums/showthread.php?t=82775

enjoy researching

 

[wiseco7mgt]

figgie how would you feel about stockecu and map ecu 2?
Do they offer enough in the way of timing control?

 

[figgie]

On a stroked 7m motor. The Volumetric Efficeny of the engine changes way to much to rely on the stock ecu for anything! Stroked engine require full control of both the ignition and injection with control of WHEN injection happens (ie full sequential injection).