head porting???
07-29-2012, 09:17 PM
#1
Race Director
Thread Starter
head porting???
I was reviewing the reciepts for my racers engine.....its a 1981 L jet 4.5L, with euro cams....BUT it has 34 HOURS worth of porting, and larger valves (doesn't say what size).... The head casting is 346.1R, which is normal for a USA 1981 with is approximately 57cc head....I just wonder how far the builder went.....it lists 16 new valves, valve seats-guides and "performance" springs with retainers.....the previous owner spent nearly $10k on this engine 
I talked to the shop, but they don't have any records back from 1991 when the work was completed....
Given my dyno # of 243whp @ 5640RPM-257 torque @ 4250RPM with classic euro cam power curves....just a touch lower since its 4.5L I am guessing they installed euro valves....and the port work made the heads roughly equal to euro heads..... I dunno until I take them apart and look at them....
I still plan on running this engine until it dies....then I will most likely go a 5.0L hybrid route.....
I talked to the shop, but they don't have any records back from 1991 when the work was completed....
Given my dyno # of 243whp @ 5640RPM-257 torque @ 4250RPM with classic euro cam power curves....just a touch lower since its 4.5L I am guessing they installed euro valves....and the port work made the heads roughly equal to euro heads..... I dunno until I take them apart and look at them....
I still plan on running this engine until it dies....then I will most likely go a 5.0L hybrid route.....
07-30-2012, 03:37 AM
#2
Rennlist Member
thats about the same as my 4.7 US motor with euro cams, headers and total intake replacement. however stock us heads. kind of makes sense that your motor and that motor (242rwhp) made the same hp. head work was equal to 200ccs. 
this means ,when you get the 5 liter, be looking for 300rwhp!
this means ,when you get the 5 liter, be looking for 300rwhp!
07-30-2012, 04:04 AM
#3
Race Director
Thread Starter
thats about the same as my 4.7 US motor with euro cams, headers and total intake replacement. however stock us heads. kind of makes sense that your motor and that motor (242rwhp) made the same hp. head work was equal to 200ccs.
this means ,when you get the 5 liter, be looking for 300rwhp!
this means ,when you get the 5 liter, be looking for 300rwhp!
Waiting for the 1/2 off sale at 928intl......
BUT that would easily bump me out of GTS3 and into GTS4.....
07-30-2012, 12:00 PM
#4
Rennlist Member
Sounds like a very healthy motor. I got 223rwhp out of my 4.5 cis. I had read a post from a gentlemen that made about the same power with euro heads and cams. Greg down under has done a lot of stuff with heads and told me he felt the best head would be what you have discribed. Either way she sounds very healthy. Interesting to see how mjch it will take. The 4.5 seems like a work horse to me!
07-30-2012, 05:31 PM
#5
Race Director
Thread Starter
Sounds like a very healthy motor. I got 223rwhp out of my 4.5 cis. I had read a post from a gentlemen that made about the same power with euro heads and cams. Greg down under has done a lot of stuff with heads and told me he felt the best head would be what you have discribed. Either way she sounds very healthy. Interesting to see how mjch it will take. The 4.5 seems like a work horse to me!
