Boost Question
#1
Member
JUNIOR BUILDER
Thread Starter
Join Date: Apr 2007
Location: West Palm Beach, Florida
Posts: 71
Boost Question
I have a 355 with 6-71 roots blower (TBS). 8.25:1 CR, aluminum heads, Cometic MLS head gaskets.
I run 8 psi boost with pump gas. Can I just change the pullies and run higher octane to run more boost? How much?
How are guys runing 15, 20, 30 PSI of boost with turbos and cintrifugal super chargers?
Thanks, Steve
I run 8 psi boost with pump gas. Can I just change the pullies and run higher octane to run more boost? How much?
How are guys runing 15, 20, 30 PSI of boost with turbos and cintrifugal super chargers?
Thanks, Steve
#2
Senior Member
RACING JUNKIE
Join Date: Mar 2003
Location: Fountain,MICHIGAN
Posts: 856
Boost?
Steve,
1 Issue?What do ou have for a Lower END?
If its all Forged and you have Good Head Bolts,Studs.It all depends on the Ammount that you want?
I Never had any Issues w/a GM Block until I made 26-28lbs of Boost,then the Heads Studs would JUST PLAIN LEAVE there Spots in the Block!
If you have a Aftermarket Block,then It will Handle More!
A GOOD Outboard Crank Support is another way of keeping the Snout attached to the Crank!
If you are looking for 15-18lbs?
Change the Pullys,Octane and Take some Timing Away!
If You want to Make More,Then I Need some More INFO on your Motor?
Later
G 8)
1 Issue?What do ou have for a Lower END?
If its all Forged and you have Good Head Bolts,Studs.It all depends on the Ammount that you want?
I Never had any Issues w/a GM Block until I made 26-28lbs of Boost,then the Heads Studs would JUST PLAIN LEAVE there Spots in the Block!
If you have a Aftermarket Block,then It will Handle More!
A GOOD Outboard Crank Support is another way of keeping the Snout attached to the Crank!
If you are looking for 15-18lbs?
Change the Pullys,Octane and Take some Timing Away!
If You want to Make More,Then I Need some More INFO on your Motor?
Later
G 8)
#3
Senior Member
RACING JUNKIE
Join Date: Jan 2006
Location: La.
Posts: 2,890
X2, a stock block 355" can't hold it, case in point 1471 blown alcohol running 30lbs boost, cracked a cylinder burned down a piston and i was running the best parts available including splayed main caps and front crank support.
JMO
Zip.
JMO
Zip.
#4
Member
JUNIOR BUILDER
Thread Starter
Join Date: Apr 2007
Location: West Palm Beach, Florida
Posts: 71
Thanks for the help guys. I should have added it is a stock GM 4 bolt block with 4340 forged crank and rods. Forged aluminum pistons.
Made 615 HP on the engine dyno in January. What can I expect if I go to 12-15 pounds?
Steve
Made 615 HP on the engine dyno in January. What can I expect if I go to 12-15 pounds?
Steve
#7
Senior Member
RACING JUNKIE
Join Date: Dec 2004
Location: austin texas
Posts: 729
I have run blown sbc on the street for years. I will give you some advice in a bit after i rest!!!! Just got home from a steel erection job for DPS.
ps i run up to 10-12 lb boost on with 93 octane. Proper jetting and correct timing and a good cooling system. Unless ur blower is a aftermarket it is not going to put out more than 10-14 lbs of boost max. Being in a street car it will put less strain on the engine, since you will get little traction.
Be back later
ps i run up to 10-12 lb boost on with 93 octane. Proper jetting and correct timing and a good cooling system. Unless ur blower is a aftermarket it is not going to put out more than 10-14 lbs of boost max. Being in a street car it will put less strain on the engine, since you will get little traction.
Be back later
#8
Member
JUNIOR BUILDER
Thread Starter
Join Date: Apr 2007
Location: West Palm Beach, Florida
Posts: 71
I look forward to your knowledge.
My Nova is 80% street and 20% 1/4 mile. As many do, I am chasing the big billboard.
My blower is from The Blower Shop. Th400 w/TB, Ford 9" with 4-link.
And no traction with street tires.
My Nova is 80% street and 20% 1/4 mile. As many do, I am chasing the big billboard.
My blower is from The Blower Shop. Th400 w/TB, Ford 9" with 4-link.
And no traction with street tires.