10.8:1 CR + boost?

1slow95

Founding Member

May 16, 2002

1,797

3

48

ohio

Dec 5, 2006

#1

• Dec 5, 2006

• #1

Can it be done on 93 octane? I can't afford it anytime soon, but I've just been curious if it would even be possible. Using a compression calculator I found online, I came up with around 10.7:1, but my block's been decked so I figure it's closer to 10.8:1 or so.

 

Adam95GT

New Member

Aug 14, 2006

2,564

3

0

Burlington, NJ

Dec 5, 2006

#2

• Dec 5, 2006

• #2

wow... thats some high compression for boost... N20 would love it but i wouldnt feel right boosting something with that high compression... i dont know enough to tell you for sure... but when i was gonna boost the JDM probe motor 10:1 compression i know i could only run about 7lbs on stock internals b4 they would be blown to o bits... but i mean i guess with a nice FMIC... and low boost amounts i guess it would be possible... id still drop down the compression...

Did a little on line searching... came up with a clasic stang running a 331... with 10.8:1 running a SC at 8 psi...

http://www.fordmuscle.com/archives/2006/08/DIYEFI/index.php

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Dec 5, 2006

#3

• Dec 5, 2006

• #3

i wouldn't do it.

 

Zero Signal

Active Member

Feb 24, 2003

2,633

2

46

Tucson, AZ

Dec 5, 2006

#4

• Dec 5, 2006

• #4

I was recently wondering the same thing since my new combo will be running about 10.4:1 and I had dreams of a KB 4-6psi down the road. I'm already going to use the steel head gaskets. I don't know if that's just asking for trouble with the short block.

 

1slow95

Founding Member

May 16, 2002

1,797

3

48

ohio

Dec 5, 2006

#5

• Dec 5, 2006

• #5

Yeah, I probably won't have the extra cash to spend on a s/c for a loooong time, and I don't really need the extra power from it. I was just curious if it would be possible in case I won the lottery someday or found a used s/c for like $500 or something. The bottom end is already built with forged crank, rods, and pistons.

 

B

bimmertech

New Member

May 3, 2005

1,123

0

0

merriam, ks

Dec 5, 2006

#6

• Dec 5, 2006

• #6

dinan and active autowerkes have been boosting M3's with great sucess for a long time now--they run around 11:1

same with S2000's

in my book low boost high compression beats low compression high boost any day.

i would run like 6-8 lbs intercooled turbo with some meth inj for that added safety. should make crazy power.

btw active auto has been known to run 18lbs on the M3.

 

Killercanary

The car that set the bar.

Founding Member

Nov 29, 1999

5,676

1

76

Altoona, PA

Dec 5, 2006

#7

• Dec 5, 2006

• #7

I knew a local guy with a Lingenfelter(sp) vet with 11:1 compression that added a procharger pulleyed for only 5lbs of boost. The car was an animal before the blower and just insane after it. they ran it that way for a few months and then one hot summers night it decided to detonate and BOOM, that was all she wrote. They fixed the engine and did not put the blower back on. It all comes down to cylinder pressure. If you keep the boost low and cool, you should be able to get away with a few lbs of added pressure. I'd try and make it as safe as possible by running methanol injection, etc. Its definitely not the best scenario, but you could do it if you really wanted to.

How much do you think that block can handle?

 

thegreentaco

Member

Feb 25, 2006

40

1

9

Sacramento

Dec 5, 2006

#8

• Dec 5, 2006

• #8

hmmm....I thought boostin 10:1 was pushin it, but damn 10.8:1. Keep your fingers crossed on that one

 

Zero Signal

Active Member

Feb 24, 2003

2,633

2

46

Tucson, AZ

Dec 5, 2006

#9

• Dec 5, 2006

• #9

Someone mentioned N2O. I thought the compression ratio limits were the same for boost and nitrous. So would it or wouldn't it be safe to run N2O with high compression? I wouldn't mind having a bottle in the back for some crazy fun from time to time.

 

Killercanary

The car that set the bar.

Founding Member

Nov 29, 1999

5,676

1

76

Altoona, PA

Dec 5, 2006

#10

• Dec 5, 2006

• #10

Zero Signal said:

Someone mentioned N2O. I thought the compression ratio limits were the same for boost and nitrous. So would it or wouldn't it be safe to run N2O with high compression? I wouldn't mind having a bottle in the back for some crazy fun from time to time.

Click to expand...

Its safer than boost due to the fact that it comes out at a temperature that is below freezing. This cools the intake charge and helps avoid detonation. Some guys I know will run a small 20hp shot on their SC'd cars strictly for the cooling properties of the nitrous. C02 has the same properties, but since it displaces O2 it will hurt performance rather than help.

 

Adam95GT

New Member

Aug 14, 2006

2,564

3

0

Burlington, NJ

Dec 5, 2006

#11

• Dec 5, 2006

• #11

Killercanary said:

Its safer than boost due to the fact that it comes out at a temperature that is below freezing. This cools the intake charge and helps avoid detonation. Some guys I know will run a small 20hp shot on their SC'd cars strictly for the cooling properties of the nitrous. C02 has the same properties, but since it displaces O2 it will hurt performance rather than help.

Click to expand...

Yerpppp! thanks for clearing that up for me KC

 

B

bonestock94

Member

Apr 12, 2005

61

0

6

NY

Dec 5, 2006

#12

• Dec 5, 2006

• #12

Tuning tuning tuning tuning tuning!!

Go very easy on the boost and get a topnotch tuner I think it'll be a fun car.

 

BlackVert

15 Year Member

Oct 3, 2003

5,589

9

98

Bethesda, MD

Dec 5, 2006

#13

• Dec 5, 2006

• #13

i'd do nitrous before i'd boost it.

 

95strokerPSU

Member

Jul 29, 2004

986

1

19

Sacramento from Philly

Dec 6, 2006

#14

• Dec 6, 2006

• #14

Spray it. I think I'm gonna get a Zex dry kit jetted for a 100 shot and a window switch. I'm at 10.5:1 CR.

 

MattZ281LE

Founding Member

Feb 6, 2000

345

1

19

Purcellville, Va

Dec 6, 2006

#15

• Dec 6, 2006

• #15

The basic SC kits for LS1/LT1 cars are 6# They are 10.1/10.5 respctively. Keep it around that with a good tune. High quality fuel would be a must.

 

ProKiller

Founding Member

Apr 26, 2002

3,064

15

78

PA

Dec 6, 2006

#16

• Dec 6, 2006

• #16

if you kept the boost low i think you would be okay. like an a-trim would be a good little s/c for something like this IMO.

about the nitrous performing a cooling affect. From what I've found and read about, it doesn't do anything but add nitrous. the cooling affect is minimal. I was looking into this a while back when a guy i knew was going to sell me his dry NOS kit for cheap. Increased cylinder pressure is increased cylinder pressure. your better off getting methonal injeciton for its cooling affects rather than N2O. nitrous is just going to raise the cylinder pressure rather than lower it from cooler air.

 

4Jenna

Founding Member

Sep 12, 2001

4,326

6

69

AZ

Dec 6, 2006

#17

• Dec 6, 2006

• #17

You would need AVgas or some type of yummi gas

 

parchisi

New Member

Apr 13, 2006

519

1

0

New Mexico

Dec 6, 2006

#18

• Dec 6, 2006

• #18

isn't AVgas leaded?

 

OrangeMustangGt

Founding Member

Mar 7, 2002

1,976

0

36

Cape Cod, MA

Dec 6, 2006

#19

• Dec 6, 2006

• #19

did anyone mention methanol injection?

suposed to be like running 120+ octane fuel.

what are ya looking for more power?! I knew if i had that combo i would be pretty damn happy for a long time......

are you thinking s/c or boost?
what kind of head gaskets do you have installed now?
with my gt0p heads i have been told i have a higher compression ratio, and that they wouldent work, but they have been fine. Actually believe it or not having a n/a cut cam will actually cause your compression to drop. it has a longer duration with both valves open to facilitate scavenging...that is how i think ive been getting away without any problems, when i used the stock cam i blew a gasket right away.

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

12

69

B.C. Canada

Dec 6, 2006

#20

• Dec 6, 2006

• #20

personally i wouldn't try to boost a car that is near 11 to 1 compression.