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Just got done with a real F headed 455 W30.
I lowered the compression to 9.8:1 as well as reducing the off the seat time on the cam by about 30* on both intake and exhaust.
Ran it on 91 E10 with bone stock intake and exhaust manifolds as well as pretty stock heads. Cam is a mild hyd roller, specs are 228/234@.050 on a 112. Lift is .555 on both, 34* total timing
Might try something more testing tomorrow but we’ll see😉.
Hope this helps.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
Finally a thread I can sink my teeth into. This data above is very similar to a 1970 W 30 rebuild a customer sent me a while back. Can you post pictures?
Just got done with a real F headed 455 W30.
I lowered the compression to 9.8:1 as well as reducing the off the seat time on the cam by about 30* on both intake and exhaust.
Ran it on 91 E10 with bone stock intake and exhaust manifolds as well as pretty stock heads. Cam is a mild hyd roller, specs are 228/234@.050 on a 112. Lift is .555 on both, 34* total timing
Might try something more testing tomorrow but we’ll see😉.
Hope this helps.
I know this... Nice numbers that are I am sure held back a lot by the stock Intake and exhaust manifolds. Appreciate the build Mark and can’t wait to get it on the butt dyno. LOL.
Ok, so I had the opportunity to go from the W Z manifolds and 2.25” pipes to headers and 2.500” pipes. Anybody want to guess the HP/tq difference and where in the rpm range? REMEMBER, stock intake, stock exhaust, OPEN crossovers, Hint, I was genuinely surprised based on my previous experience doing the same comparison on other builds.
Let the speculation begin!!
Last edited by cutlassefi; March 20th, 2021 at 03:49 PM.
Ok that’s your guess on HP but what about Tq and where in the rpm range was the biggest difference?
Pure guess would be 20-30 ft-lb. I'm kind of torn about the RPM range. I can make a case for low and for high. Given that the intake side is probably choking the high end, I'm going to say biggest improvement at the bottom of the pull.
Pure guess would be 20-30 ft-lb. I'm kind of torn about the RPM range. I can make a case for low and for high. Given that the intake side is probably choking the high end, I'm going to say biggest improvement at the bottom of the pull.
Location: Colorado Springs Colorado/Thousand Oaks Ca
Posts: 1,721
A friend of 442 Dude on here dyno tested a rebuild of a stock 1970 W-30 455, with and with out exhaust manifolds, maybe he can post the article he sent me.
A friend of 442 Dude on here dyno tested a rebuild of a stock 1970 W-30 455, with and with out exhaust manifolds, maybe he can post the article he sent me.
If you’re going to post, just make a guess for crissakes.
VORTECPRO......here is the article you were referring to. It was written years ago but shows all the empirical data between the manifold vs header torque/HP test at altitude.
Is this for Mark's new TV show, Rocket Masters?
Why do I feel like this is the Dulcich role?
Lol, I wish!
Here you go guys. I have a theory about why the results are what they are as well as the effect that an open exhaust cavity has on power and tq and where.
The top pull was done with 34*, the bottom pull was with 32*, go figure.
Last edited by cutlassefi; March 21st, 2021 at 06:53 AM.
Lol, I wish!
Here you go guys. I have a theory about why the results are what they are as well as the effect that an open exhaust cavity has on power and tq and where.
The top pull was done with 34*, the bottom pull was with 32*, go figure.
W/Z manifolds are better than most factory exhaust manifolds, due to the internal runners. I'd guessed that the short "tubes" in those manifolds would actually be biased towards the high end, thus the lack of improvement with headers there. I'm curious why the headers seem to nose over at the top end. Is there some weird resonance in the long-tube primaries?
W/Z manifolds are better than most factory exhaust manifolds, due to the internal runners. I'd guessed that the short "tubes" in those manifolds would actually be biased towards the high end, thus the lack of improvement with headers there. I'm curious why the headers seem to nose over at the top end. Is there some weird resonance in the long-tube primaries?
I pulled the throttle back a little prematurely on that run, sorry.
I believe the better scavenging of the headers pays off more at the bottom end because of the open cavity in the heads and intake and the overall traditional effect headers have on an engine. Add to that, as you pointed out, the intake tract on this is somewhat challenged, hence the minimal gain up top.
March 19th, 2021, 02:15 PM
