here's the situation, I think this will be a great 'experiment'

I 'maxed' out my heads when I put in a bigger cam. it made absolutely no more power anywhere, but lost TQ below 4500. this is with 5.7L heads and 2.02 intake valves. Soooo, I had my head porter put in 2.08 valves. my cam is a FMS 253/261 .642 110+4. I'm running stock rockers and Melling lifters. oh, and this is a 408.

here's the results in CFM
.500 +4
.550 +6
.600 +12
.650 +17

flow numbers below .500 were completley unchanged. The exhaust was also left the same.

any guesses on results?? I'm installing the heads tomorrow and will have it dyno'd saturday. I'm guessing +10rwhp in my powerband.

 

i would say that looks about right to me

 

8-14 rwhp gain is the range I came up with, but 10 rwhp gain is pretty much a safe bet.

 

I'd say 10-15rwhp in the 4500 up area.

 

I say from 4500 up you'll see 19RW....

 

sorry, this has been delayed a week. broke my driveshaft at the track

 

well, preliminary results are seriously diapponting.

down 15rwhp and 25rwtq on the EXACT same hp/tq curve. it put down 530/490. on that dyno before it put down 545/515

other things I changed: added FTRA, and 28W tires from regular 28X10.5's.

a/f was about 12.5:1

the only encouraging thing is that a buddy of mine was down 30rwhp/tq from a few months earlier and hes barely even driven his car. I'm going to do some tuning on the street and put the regular 28's on and go back to see what it does.

 

well, I don't have enough open spring pressure now its only 375 and I need about 450. I'll swap them out and redyno. was getting some bad valve float.

 

might just be different day u dynoed

i saw a 402 dyno 499rwhp one day and 470rwhp another day w/o any changes on the same dyno

 

maybe a stupid question...any tuning after the valve swap or not

 

when I find the dyno sheet, I'll post it. its floating the valves.

no tuning needed. a/f is 12.8-13.0:1. no knock.

 

I was beginning to wonder what was going on there. Good to know that you're getting the problem fixed. Be sure to kee up updated with the new dyno numbers!

 

ok, I jumped the gun. its not floating them, I have no idea what the hell is wrong. its down 20-30rwhp/tq everywhere. did a compression check real quick and it was ok. going to pull the intake and check for cracks or somthing. I'm lost on this one...

 

pulling the heads tomorrow to have the seats looked at. maybe results in a week...

 

If the only thing changed in your setup was the heads, maybe the max port job cost you airspeed/velocity or perhaps your mid-lift flow is not as good as it once was. Sorry to hear your results were not positive. It sucks to throw money away.

 

mid and low lift numbers are the same. wait a week and then look at my results. something is not right. I've not given up yet. I think my valve seals need some work...