9 to 1 compression

K

koch186

Member
Joined
Sep 14, 2013
My motor is at 9 to 1 compression. I talked to my Gn mechanic and was told I'll have to use race fuel due to detonation or have a custom chip burned and turn boost down to avoid detonation. Any thoughts? Also can you have two different chips or setting ?
 
If you want to make any power you will need race fuel anyway. 9:1 is fine. If you are planning on running 93 octane, you are limited to around 18psi even at stock compression.
 
koch186 said:
My motor is at 9 to 1 compression. I talked to my Gn mechanic and was told I'll have to use race fuel due to detonation or have a custom chip burned and turn boost down to avoid detonation. Any thoughts? Also can you have two different chips or setting ?
Click to expand...

You might be surprised how much power it makes even at "low" boost with a 9:1 motor. Compression ratio itself doesn't matter; it's the combo, so learn how to tune and see what your car likes. Get a scanmaster if you don't already have one or a logger.
 
My engine has much better power and drivability with 9:1, especially on 93 octane.

Posted from the TurboBuick.Com mobile app
 
Get an ALKY CONTROL system from Julio and you can get up to 26lbs. of boost on 93/alky and the right chip depending on the rest of your combo.

There is no info in your sig, if you put that info in there it would help now and in the future for others to give accurate advice.

The more detailed the info you give the more accurate the advice you will receive.
 
robzombie said:
Get an ALKY CONTROL system from Julio and you can get up to 26lbs. of boost on 93/alky and the right chip depending on the rest of your combo.

There is no info in your sig, if you put that info in there it would help now and in the future for others to give accurate advice.

The more detailed the info you give the more accurate the advice you will receive.
Click to expand...

Plenty have been past 26lbs even with just a single nozzle on an alkycontrol kit. That's a pretty blanket statement and may cause him to blow up his car b/c he read it on the internet. Good call on the signature, but let the noob learn slowly so he doesn't blow it up right away. He may only get 22psi out of an alky kit with his comb and tuning ability; it's too early to make such proclamations.
 
we4Mateo said:
Plenty have been past 26lbs even with just a single nozzle on an alkycontrol kit. That's a pretty blanket statement and may cause him to blow up his car b/c he read it on the internet. Good call on the signature, but let the noob learn slowly so he doesn't blow it up right away. He may only get 22psi out of an alky kit with his comb and tuning ability; it's too early to make such proclamations.
Click to expand...

This is true, I have been to 28lbs. before running out of injector. I didn't tell him to go that far, I only told him that 26lbs. is possible which happens to be the case for me with an alky kit.

That is why I said he would get more accurate answers if he would provide more info on his setup. I admit it's a blanket statement and sometimes forget that I was where he is now and expect people will do there research before just throwing a bunch of parts on and hoping it will work as they expect it to.

You must be slacking also as you didn't put the obligatory sentence of READ,READ and then READ some more before thrashing on your car and blowing it up.:D

I didn't think he was that much of a noob as he's been a member since 2011, but I guess the low post count should have been the give away.

I will try not to drop the ball in the future.
 
9.0-9.5:1 is pretty normal for a high output v6. It's not for everyone and if you're worried about detonation or what you can get away with id stay with the stock CR. It's possible to have a higher manifold pressure and less detonation prone engine than another combo with lower manifold pressure.


Sent from my iPhone using Tapatalk
 
I had aloy of help with my build. And as I was reading the spec sheet that my builder gave me I saw the final compression to be at 8.6 to 1. I for some reason had the 9 to 1 ratio in my head and spoke with the guy doing the final tuning and told him it was at 9to1, so he was making me aware of the situation. But I'll be fine with the ratio that its at. I'm new at this and I'm trying to absorb all the info I can. I appreciate everyone taking time out of there day to spread there knowledge. I rebuilt the motor it has 100k and it wiped the cam. I have a 49 turbo wth injectors alky kit bigger down pipe, custom radiator ,scanmaster, hotwire and pump. 218 cam full roller Harland sharp roller rockers. Everything has been replaced. Still have to get tranny done and figure out what stahll to use.
 
My motor has a 9 to 1 CR in it and it runs fine. The motor will want more fuel at lower rpms so make sure you have a way to add fuel in the tables to compensate.

Get with Dusty at PTC for your converter he will get it right.

The correct injectors and alky kit will get you into the high 9s, on a single nozzle. Tuning it is the key.

So absorb much about alky and pump gas. You will be surprised how much power you can make. You will max out that turbo you have. Just don't blow it up. Baby steps.......
 
Cam seems a little big for stock heads and a 49.
 
9:1 actual (real life) static compression isn't as easy to get as most people think with off the shelf pistons. I had to do all kinds of stuff to my 4.1 to get 8.9999:1


oh, and you need a new GN mechanic.
 
koch186 said:
Why do i need a new mechanic ?
Click to expand...


Because 9:1 doesn't cause detonation. Period (and not the presidential kind, the actual kind). I only hear overly simplistic statements like that from people you really don't want touching your engines.


But lets back up a little.... how do you know your engine is 9:1?
 
earlbrown said:
Because 9:1 doesn't cause detonation. Period (and not the presidential kind, the actual kind). I only hear overly simplistic statements like that from people you really don't want touching your engines.


But lets back up a little.... how do you know your engine is 9:1?
Click to expand...
 
I was told in the middle of the build that its going to be right around there. My engine builder gave me my spec sheet of the build today . I wrote that last night before I got the spec sheet and I talked to my Gn buddy last night he said its just something to take into consideration before he gets his hands on it. Just trying to prepare me that we might have to have a custom chip made or race gas. I wrote earlier in the thread that The spec sheet says its at 8.5 or 8.6 to 1 can't remember. I was just kinda nervous last night . he's a local guy around Cleveland that has a lot of experience with them.
 
Don't worry about it , I am very close to 10.0:1 in my car, 93 and alky and have it at 25 psi on the street right now and still tuning.

That cam is too large for the flow of your heads though. May be a pig down low in the rpms up to about 4000

Bryan

Posted from the TurboBuick.Com mobile app
 
With any good mods you need a "custom" chip to take advantage of them anyways. TT can make an alky chip that matches your mods and you're good to go.
 
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