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View Full Version : 10.3-1 compression with 10psi boost?????



WELTERRACER
03-11-2005, 02:38 PM
My procharger is comming.. Ill have it on MONDAY..

I was going to pull the intake and heads and headers and install .080 head gaskets to drop the compression down to 9.3-1.. (aluminum pro 1 heads)

Doing this is a real PAIN..

What would the possiblities of running the high compression with the 10lbs of boost from the procharger.. and if so... what fuel would i have to run??

Or should i just suck it up and pull the heads..??

Jagarang
03-11-2005, 03:59 PM
KaBOOOOOOOOMMMMmm!!!!

JLM
03-11-2005, 04:03 PM
on a fuel injected motor you will need to have a SERIOUSLY safe tune making sure you've got enough fuel in your cylinders to keep the air charge down as much as possible. I'd look into a methanal injection kit as well. you won't be able to run it on pump gas. If you run 104+ plus through it making sure you've got the collest intake charge as you can with a good tune with lots of fuel and low timing you should probably be ok.

SDMAN
03-11-2005, 06:48 PM
On gasoline you can forget it. Alcohol could be made to work if you could get enough of it into the engine.

rancherlee
03-12-2005, 05:54 PM
10.3:1 @ 10psi on pump gas, NO WAY
9.3:1 @ 10psi on pump gas, Peachy

I'm running 9-10psi on my aluminum headed 3.8L V6 with 9.2:1 compression and the timing is fairly agressive but I feed it lots of fuel (about 11.5:1 A/F under boost).
( I have 20,000 miles on it and 100's of runs down the track with the supercharger and 91 octane)

WELTERRACER
03-13-2005, 10:27 AM
What if i use 92-93 octain pump gas and poor in a can of 104 octain boost each fill up?

camcojb
03-13-2005, 10:30 AM
What if i use 92-93 octain pump gas and poor in a can of 104 octain boost each fill up?

104 octane boost would be worthless. If you were willing to mix enough race gas or Xylene/Toluene you could get the octane up there. Plus there's stuff from Torco (leaded version) that works very well. 104 octane boost wouldn't add even a single point to your octane, it's rated in 1/10's of a point.

Jody

WELTERRACER
03-13-2005, 10:59 AM
104 octane boost would be worthless. If you were willing to mix enough race gas or Xylene/Toluene you could get the octane up there. Plus there's stuff from Torco (leaded version) that works very well. 104 octane boost wouldn't add even a single point to your octane, it's rated in 1/10's of a point.

Jody


I thought 104 octain boost added 6-7 points to your octain?? Which if i had 93 octain it would make it 99-100 octain right??

camcojb
03-13-2005, 11:05 AM
I thought 104 octain boost added 6-7 points to your octain??


It would be great of that were true. Unfortunately it's not even close. .6 to .7 of ONE point of octane maybe, but not 6-7 full tenths. I would say do not waste your money.

The Torco leaded version adds about 5.5 full points when i quart is added to 20 gallons of gas. It's between $11.50 and $26 per quart shipped to your door depending on if you buy individual quarts or a 5 gallon pail.

Jody

WELTERRACER
03-13-2005, 11:23 AM
Man, sounds like Misrepresention on the back of those bottles than... Ive bought a few bottles of them in my life and it sounds like i got screwed than... I thought it was adding 6-7 full points..

WELTERRACER
03-13-2005, 11:26 AM
What if i mix Race fuel 50/50 with Pump gas?? 101 octain is readily available at the local gas station!!

camcojb
03-13-2005, 11:55 AM
What if i mix Race fuel 50/50 with Pump gas?? 101 octain is readily available at the local gas station!!


If you mix 93 and 101 in a 50/50 mix you'll be very close to 97 octane which is a nice mix. Mainly keep your air temps down (cold air box) and an intercooler works wonders. Another thought that has worked very well for me is water/alcohol injection kits to cool the compressed air and absorb some heat out of the chambers.

Jody

WELTERRACER
03-13-2005, 12:00 PM
SO your saying a 50/50 mix will work with the 10 psi and 10.3/1 compression?????

nancejd
03-13-2005, 12:03 PM
Just my opinion here, but if I'd dropped a bunch of money on a supercharger, I would spend the time to swap the head gaskets and get the compression where you want it. Who wants to mess around with having to mix gas, especially if you are on the road somewhere?

WELTERRACER
03-13-2005, 12:10 PM
Just my opinion here, but if I'd dropped a bunch of money on a supercharger, I would spend the time to swap the head gaskets and get the compression where you want it. Who wants to mess around with having to mix gas, especially if you are on the road somewhere?


Ya, i know i should swap the gaskets, but than again i dont drive this car more than 40miles in any dirrection.. I dont have a reason to go farthure than the race track which is 35 miles away from the house.. all car shows ive entered were not more than 8 miles away from my house..

WELTERRACER
03-13-2005, 12:11 PM
I could always tear it back apart later and add the gaskets too.. I just want to see how she works the way it is currently..

nancejd
03-13-2005, 12:23 PM
Like I said, if it was me I'd change it before I ran it, but I saw what detonation did to my friends Procharged LT-1 after bits of piston started swapping holes. If it doesn't work right there is a potential for large amounts of internal engine damage.

camcojb
03-13-2005, 02:04 PM
Do you have to run 10 psi? I'd get a bigger pulley to drop it to about 6-7, you'll be surprised at the power increase even at that boost.

Are you going to intercool it? Water/alcohol injection? What about timing?

Jody

WELTERRACER
03-13-2005, 03:22 PM
I want to run 10psi.. as i want to make 630-650hp.. Which should be easily attainable as it already makes 425-440hp...

It is going to be carburated.. i currently run 36 degrees total timing.. so im guessing i will have to tune it back to about 34 degrees total timing..

camcojb
03-13-2005, 03:51 PM
I want to run 10psi.. as i want to make 630-650hp.. Which should be easily attainable as it already makes 425-440hp...

It is going to be carburated.. i currently run 36 degrees total timing.. so im guessing i will have to tune it back to about 34 degrees total timing..

With that compression and boost you likely won't be able to run 34 degrees. I'd start at 26-28 and work up, and then only if you're going to be running 97-98 octane+

Jody

Fuelie Fan
03-13-2005, 06:09 PM
If you're pretty confident that you're already making 425+hp, I don't think you'll need 10 psi to get up over 600. 7 psi would actually be pretty close.

If you're going to do this, please be conservative with the timing and fuel. 34deg is a healthy amount for a NATURALLY ASPIRATED 10.3:1 engine. We'd hate to see you lose parts. If I were you, I'd even consider straight 101 octane for the first time out

Steve1968LS2
03-13-2005, 07:03 PM
I thought 104 octain boost added 6-7 points to your octain?? Which if i had 93 octain it would make it 99-100 octain right??

Thats just good marketing on their part.. Maybe if you added gallons of the stuff :)

A stock LS1 runs at just over 10:1 compression and you can safely run 6-7 lbs of boost..

You COULD run 10psi in your set up and if your tune is PERFECT it might last a while. If I were you I would either run less boost or do the deal with the head gaskets.

WELTERRACER
03-24-2005, 12:26 PM
Frank from Prodogy just talked to ATI for me..

I can run 10.3 with 10lbs of boost as long as i use 101 or more octain or.. 92+114race fuel in a 50/50 mix..

if i drop it down to 6lbs of boost i can run 92 octain no problem.. or with an intercooler i can run the 10psi on pump gas.

pdq67
04-30-2005, 04:37 PM
A little late, but I hope this is still of use??

Kemco Lead Supreme 130 Real Lead Gas Treatment.

It can raise octane by whole numbers and not just decimal points b/c it contains REAL tetraethyl lead (TEL). Only problem with it is that it will poison the cat. Thatís why the EPA removed TEL for gasoline years ago b/c it is a heavy metal and poisons cats! That and the stuff is highly poisonous!

pdq67

Rybar
04-30-2005, 06:59 PM
I used to run 8#'s on my LT1 T/A which had a stock bottom end and 10.5:1 compression. It did have an intercooler, and did run pig rich with the FMU. This was also with 94 octane pump gas and a stock tune. Motor is still doing well and put down 415 rwhp.

Don't know if this helps, but I'd say tune it rich, run higher octane fuel or drop the boost and run the 10.3 or drop the compression and keep the 10 #'s.

Torbjorn
05-21-2005, 04:17 PM
With 10 psi of boost on 10,3:1 its just a question if you prefere to change your gaskets before or after the big bang!
Just go on and change your gaskets. You will regret it if you don`t

Torbjorn