Thread: 9.5:1 to 8.5:1 What to expect?

Coheed, with your elevation higher compression makes a lot more sense. Since your oxygen content is lacking you need it force more air in.

The VE head is a great idea! but daamn expansive, so maybe in the future hehe. I will use the DET just the way it come, but if something go wrong and I have to open that DET, I will swap the lowport head (and put on it the sodium valves).

Hey Vadim! Elevation is a good thing to think about, cuz I live in a city that is like 689 ft over the sea, so maybe a 9.5 isnt a good idea for 20 PSI car.

About the lag, I sounds good to know that it will be easy to lunch the car on the drag track with a lower compresion. And then I will have to learn to live with slow car everyday I go to work haha (due the low's RPM on the city).

What about the gas millage? Almost the same on both compression on daily driving?

689ft that's nothing. I'm at 1,300ft and it's still fine .

Here is a real question, what ecu are you going to run? Can you tune or will you use a base tune or go to a tuner?

If you are not running a real time tunable ECU, or have no access to burn chips, or can't tune nor have access to a good tuner, then stick to 8.5:1. This will let you get away with more mistakes. It will also let you get away with crappier gas, still use 91 though.

I live at the same elevation as Coheed (4,800 ft) and I still prefer the lower compression. I don't have any problems with traction and I spool about 700-1000 RPM's sooner than Coheed. I imagine it's because of less low end HP/torque. More of a pro than a con. The engine will make up for it in the high RPM's anyway.

Listen, Don't worry about getting caught up in trying to decide which compression you

"need". You will hardly tell the difference between the two. And also seeing from what you

know and want, a basic DE+T or even a DET would be good for what you looking for.





Chris.

Thats one thing i like about my car over my friends turbo cars, the daily driveability. I dont know if any of you guys have rode in a srt4 but its funny to watch those things have to make boost to go anywhere.

Ooh I thought that for a lower altitude it will be more density in the air, so we will have more air on the cilinders, making a lil more hard for 9.5:1 compression turbo engines.

I'm going to use a nistune ecu.

So it appers that it is very small diference between both engines, I will get a avenir engine to put it on my 200SX.

I almost forgot to say! I will be using water/methanol injection but planning to use it only for drag (do no know how much it will use for a daily driving).

Well with more air you will get more power. So denser air is good, like in the winter . That more air wont hurt the 9.5. Honestly the summer heat hurts it more.

turbos will make more heat with more altitude also since the PR is pushed higher. But that's all too much thinking.

Which Nistune are you going with? Also are you OBD1 or OBD2?

I highly suggest you go with a Calum Based ECU and get tuner code for it.

Or this one: B13 ECU