to make a long story short...
my crankshaft is trash, the keyway tore it up so i need to replace it...
i currectly have a B20 short block w/ gsr head... NO SLEEVES...scat pistons 9:1:1... eagle h beam rods...block guard...t3/t4

since i now need a valve job and new crankshaft i am planning on putting in a new B20 bottom end BUT i will NOT be getting the bottom end built... no pistons... no rods... stock compression... but YES on a block guard (not like it will help much)...and slapping the t3/t4 back on...

here are my questions...

1.) what is the stock compression on the b20... i heard they have 2 different levels for b20's...IS THAT TRUE?!

2.) i know that 10 psi is safe for stock sleeves... but how much hp/tq is safe for the bone stock b20's pistons and rods / rod bolts?

3.) what other issues would i be looking at since i am not going to rebuild the bottom end?

i heard a while back that there might be an issue with the b20s stock rod bolts... can those be changed out and replaced with ARP rod bolts WITHOUT removing the crank from the bottom? or do the bolt heads face UP towards the head?

thx alot for ur help.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostnubII &raquo;</TD></TR><TR><TD CLASS="quote">to make a long story short...
my crankshaft is trash, the keyway tore it up so i need to replace it...
i currectly have a B20 short block w/ gsr head... NO SLEEVES...scat pistons 9:1:1... eagle h beam rods...block guard...t3/t4
</TD></TR></TABLE>

boost on a thin sleeve motor like a B20 is playing with fire

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostnubII &raquo;</TD></TR><TR><TD CLASS="quote">
1.) what is the stock compression on the b20... i heard they have 2 different levels for b20's...IS THAT TRUE?!
</TD></TR></TABLE>

Correct. B20B is 8.8:1. The later model B20Z is 9.6:1. These numbers are in stock form. Now assuming you have an unmilled head and block, are using a stock headgasket and internals, your CR numbers with a B18C1 head would roughly be:

B20B bottom end 9.2:1
B20Z bottom end 10.1:1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostnubII &raquo;</TD></TR><TR><TD CLASS="quote">
2.) i know that 10 psi is safe for stock sleeves... but how much hp/tq is safe for the bone stock b20's pistons and rods / rod bolts?</TD></TR></TABLE>

UMMpossible to calculate. But in my honest opinion, stock output isn't safe for stock rod bolts. I've got a windowed B18 to prove it!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostnubII &raquo;</TD></TR><TR><TD CLASS="quote">
3.) what other issues would i be looking at since i am not going to rebuild the bottom end?</TD></TR></TABLE>

Umm, lots. Search will be your friend here. But a short list - a weak bottom end, potentially boosting a wore out motor, rod bolts streaching, hot spots on cast pistons, etc....

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostnubII &raquo;</TD></TR><TR><TD CLASS="quote">
i heard a while back that there might be an issue with the b20s stock rod bolts... can those be changed out and replaced with ARP rod bolts WITHOUT removing the crank from the bottom? or do the bolt heads face UP towards the head? </TD></TR></TABLE>

ARP rod bolts are highly recommended however, they need to be installed by a professional (or at least someone with the proper tools and experience) who can resize the rod ends after installation. This is all stated in ARP's literature.

 

so at the MINIMUM i should at least have a shop replace the rod bolts?

 

rod bolts will strech with RPM's right?
wont be super revn' the motor...
im just wondering what a safe / max amount of hp on a bone stock B20b

 

rod bolts strech with rpm's....
would 300 hp sound ok for a stock b20b bottom end?