View Full Version : 4/7 swap? --Stupid question?


bayer-z28
02-19-2006, 10:04 AM
Ok, I know that magazines are not allways the greatest places to go for info. But I read them anyway. I've reently read an article in Hot Rod about swappign the firing order to get more power.

seeing as the LS1 Firing order is... 1-8-7-2-6-5-4-3... you take the accompaying cyl..(sp?) in relation to the cycles...

1-8-7-2
6-5-4-3
I-C-P-E

The power stroke on 4/7 are opposite. You swap them and it supposedly gains about 10hp. Seeing as the cam determines the firing order.

Am I insane?

67Ranger
02-19-2006, 10:38 AM
sounds interesting... i'd like to see too

Mike454SS
02-19-2006, 11:42 AM
Older smallblocks were 1-8-4-3-6-5-7-2...LS1 was the first small block where GM did the 4-7 AND 3-2 swap...go read about how many people tried 4-7 swaps on older smallblocks to get 10 HP...now they're saying to do it to an LS1 to put it back the other way...I find it kinda funny.

-PEPE-
02-19-2006, 11:44 AM
Unless I'm just completely wrong here the LS engines have the 4/7 firing order already switched by GM when they designed that engine, the LT engines do not, so us LT guys do custom 4/7 grinds. That issue was one of the first side by side comparisons of identical cams in the same identical engine (great article), other research I've done on it was just builders stating it's good for 10hp but little actual proof like a dyno sheet and (no other changes) being made to get a true benchmark. The gains for most on average are not necessarily a full 10 hp, some gains are as little as 2-4 hp. But it costs such a small amount to go ahead and do the swap.

427
02-19-2006, 09:07 PM
The LS series engine already has the preffered order.


Kurt