Just wondering how you know when its time to move up. I know some people swear that 48mm is big enough and some say go bigger, but I was wondering if there is any way of telling... like from manifold absolute pressure, I am getting tuner cat so just wondering if theres another way other than guessing.

 

Search in LT-1 tech since this has been beat to death about 2 times a week and isn't really advanced I know myself and Fred awnsered in a single post just yesterday on the same subject.

-Shannon

 

Simple rule is that you really should care about the CFM level. A 48mm probably is not enough at any level, while a 52mm will be. Then when you move up to the 1000cfm then you have a engine on your hands and that will support 650 hp, I think that the 1300cfm Monoblade is a bit much for almost anything, but it can't hurt if you have a ton of power.

Bret

 

there was just a post yesterday in lt1 tech i beleive, something like this:

396 engine at 104% VE spinning 7200rpm, takes in 866cfm
so a 58mm supporting 1000cfm only needs to be 86% open to get WOT
or.... a 52mm should be able to get full power when fully open

makes sense to me

if i was buying one though (and probly wouldnt until making over 400hp?) i'd probly just go ahead and get a 58mm for (maybe?) crisper throttle response and room for growth

doesnt seem a 1300cfm monoblade would be necesary for any small block application thoguh

 

CFM is measured at a specific pressure drop - i.e. vacuum or restriction. The rated CFM is at a restriction, however small. If you don't mind that restriction, stick to CFM numbers.

A.

 

Perhaps, or perhaps not. It is perhaps worth noting, however, that three of the most powerful pump gas NA LT1s that I know of all use an Arizona Speed & Marine 1300 CFM monoblade.

Phil Tobin's 403 ("Hoover")... 500 RWHP and 456 RWTQ
http://phil.tobin.net/Hoover/modifications.html

Brian Bieller's 396... 597 BHP and 481 lb-ft.
http://www.lt1motorsports.com/streetfighter.htm

My 396... 647 BHP and 552 lb-ft.
http://www.c-zone.net/markm/JimLaBre...d/P1190044.JPG

 

Jim

That's an awefully snazzy looking motor you have. Are those AFR 215 heads? Also what compression are you running? Is the motor streetable?

 

Thanks, yes, 11.8:1 according to Mark, and yes, on pump gas.

 

Guess the word of the day is: congratulations.

You certainly caught my eye.