Yellow Bullet Forums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1
I have made the switch from twin turboa LS based 408 to a twin turbo 555 BBC.
I now have some worries about the block.
It's a Mark IV Bowtie block bored 4.56 with a 4.25 stroke
The engine has the usual foged blower pistons, billit aluminum rods, Lunati blower crank. My concerns are the cast main caps with ARP studs. It does not have steel main caps with the usual angled or splayed studs. I'm thinking it might have reliability issues above 1400 hp.
This engine previously ran a 8-71 blower with nitrous with zero problems @ 1400 hp and 6800 rpm.
I know turbos put less stress on an engine than other forms of power adders because of their linear power curve, so I'm hoping for 1600 hp without worry.
Any thought on this ? Should I change to steel main caps?
 

·
Registered
Joined
·
699 Posts
even without the billit caps that block is a strong piece. my buddys 540 is a steve moris 1500 hp setup with stock caps and has never had an issue. but it has spent most of it's life as a 1250 hp pumpgas tune on it .
 

·
Registered
Joined
·
510 Posts
If you was making 1400 with the blower, I bet the parasitic losses from that would add up to more than the 1600bhp you want to make, never mind the fact that turbos tend to be less hard on engines overall anyhow.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #6
I think I will leave it alone for now, the engine is solid with only 15 passes and 9 Dyno pulls. I pulled the pan to weld turbo oil return fitting in , I pulled a couple main and rod caps, the bearings looked perfect . Gonna keep moving forward.
 

·
Registered
Joined
·
2,872 Posts
So what's the limit like 2k then
 

·
Registered
Joined
·
16,756 Posts
So what's the limit like 2k then
I was cracking the blocks Around the head bolts at around 1700hp . Fill the block and good luck my friend never know I seen some crazy shit over the years you might get lucky and make 2 k with no issues
 

·
Registered
Joined
·
2,872 Posts
Damn you figure stock blocks done 1700 filled I would of thought a bowtie could do a couple hundred more
 

·
Registered
Joined
·
219 Posts
never on a dyno but by my 1/8 times and weight and those badass online hp calculators i was making about 1900 with a 10.2 bowtie block half filled 14/71 blower on alcohol.
guess what? yup the block is in the machine shop getting fixed right now cause two cracks from the head stud down into two cylinder walls :(
ive also read that the bowtie blocks were about as strong as a dart bigm block. not looking that way
wonder if turbos will be easier on the block compared to the 14/71 blower instant torque and stress??
 
1 - 15 of 15 Posts
Top