NewbVetteGuy

THIS thread on speedtalk seems relevant all of a sudden. The Weiand "Speed Warrior" (formerly "Stealth) have big ports and come highly recommended by some VERY well known engine builders on that thread.

Holley lists it as supporting from 1,500-6,700 RPM and there are reports on that SpeedTalk thread of it supporing a 400 SBC up to 6,400 RPM.
http://speedtalk.com/forum/viewtopic.php?f=1&t=26774&sid=dca6cd9ac5 1a963e269d7e70963530b0&start=15

(It's kind of interesting that there's not many other dual plane intakes mentioned in the list of good, big-port dual plane intakes for SBCs...)


Adam

NewbVetteGuy

https://www.holley.com/products/inta...lds/parts/8150

NewbVetteGuy

But his stock vacuum brakes aren't going to be happy with a 107 or 106 LSA, are they?

Adam

REELAV8R

With a roller cam, he should be fine at 10 to 12 inches of mercury at idle. Flat tappet might be a problem though.
My 108 LSA roller cam on my 350 is around 10" at idle in gear about 550 to 600 RPM brakes work good. 14" @ 800 RPM. So a 107 on a 383 should be as good or better. My vacuum numbers are at 4000+ altitude as well, closer to seal level it should be a bit better. I'm sure a 107 would work and pretty sure a 106 could work as well for adequate vacuum. Tune is key of course. Bad tune and you get bad vacuum.

REELAV8R

Port size on that looks good. I wonder what the min CSA is though. On my 2101 the min CSA was not the port size, it was on the last turn just prior to the port. That is where it necked down pretty good.

NewbVetteGuy

It's definitely doable but you have to go with more duration / RPM to get there.

I just pulled up the list of Howards SBC roller cams that have .560 lift and the smallest one that gets you close is 110525-10 280/286, 227/233. And it's 469 HP @ 6,000 with 1 3/4" primary headers and a 950 CFM carb and an intake that keeps flowing to 6,000 RPM.

To clear 475 gross HP with 0.560" lift in Howards SBC Roller catalog you have to step up to 110635 which is 290/290, 237/237 duration on a 110 LSA, 4 deg of advance. That's rated at a 2,400-6,400 RPM range but I like it for the AFR heads because it has no extra duration on the exhaust side. Desktop dyno says that it would make 483 gross HP @ 6,500 and 441 ft lbs @ 4,500 on a 355. Or on a 383: 482 HP @ 6,000 (515 HP with open headers) and 467 ft lbs @ 4,500 RPM -WOW I LOVE that cam for a 383 with AFR 195 heads!

Adam

NewbVetteGuy

Nice. I'm running a 110 LSA on my 350 (56 degrees of overlap) -Mike Jones recommended I not go any tighter to keep my brakes happy. -I DID Notice that the Total Seal pamphlet that came with my gapless rings said that they would increase engine vacuum vs. traditional rings, so I kinda wish I would've gone with a 108 LSA. David Vizard's "128" formula recommends a 108 LSA for a 350 and a 106.5 LSA for a 383 and claims its worth +20 - +30 ft lbs of torque at the torque peak on a 383 vs. a 110 or 112 LSA.... (Those numbers sound crazy.)

Adam

Jebbysan

Little Mouse

Port velocity is a double edged sword you dont want to go to low air speed but you dont want to high. To high velocity tells you picked to small head. No chance a 195 head on a 383 drop the velocity to low.

REELAV8R

Strokemyaxe

resdoggie

I would disagree.

You guys can play with your desktop dynos all you like but here are real world Mustang dyno results for my Howard's roller with 0.560" lift. Dyno guy said that equates to somewhere north of 450 hp.

Edit: The results were with my 4" tall K&N air cleaner in place.

jb78L-82

Agree!

RWHP 357-360 on a Mustang Dyno is AT LEAST 475-480 Gross HP, probs more because it is a Mustang dyno, not a dynojet. I believe you are getting these results with a 355, 10.7 compression, Howards roller ,560 lift with AFR 195's AND a 650 CFM Holley? I am fairly confident my 355 with AFR 180's, 650 Holley, 10.2 compression, and mild roller .525 lift is in the 440-450 Gross range.

A properly built 383 can get the same numbers as above with slightly less compression, slightly milder roller cam with AFR 195's and the same 650 CFM carb at a slightly lower RPM, about 300 RPM less for both HP and TQ.

NewbVetteGuy

Your build is great. I'm really hoping I can end up with close to that on RWHP but if I get close I'll be happy.



Two things though:
1. Going from RWHP to engine HP is not super precise so it's pretty hard to say whether 357 RWHP = 470+ crank HW (which was the OP's goal with AFR heads and the CompCam that he chose). Even with an 80% reduction for an automatic transmission, 352 RWHP = 440 HP @ the crank. -You've got a manual transmission, and if I remember right an underdrive crank pulley, so I'd "back of the napkin" a less than 20% loss, but again it's not easy to accurately go from RWHP to FWHP. I think the dyno software used, right is probably more accurate than going from RWHP to FWHP. (I've used a number of programs so far and the one that I'm using is the most optimistic as it's just looking at airflow from the heads (which are normally measured on much larger than a 4.030" bore and overly optimistic), the cam specst and valve timing events overlaid on piston CFM demand at each RPM point. -The more advanced programs take into account friction / drag from piston rings, windage losses, and loss from accessories and the numbers only get lower with the more advanced programs.

2. I totally missed the cam that you used in Howard's lineup. (110525-10) 280/286, 227/233, 110 LSA, .560/.560 lift, right? I just modeled a 355, 10.7:1 CR, single plane intake (I was only modeling dual planes yesterday), AFR 195cc heads, your howard's cam, a 650CFM carb, 1 3/4" headers with full exhaust and mufflers. -And I got 481 HP (flat from 6,000 - 6,400) and 458 ft lbs from 4500-5000 RPM. (The single plane intake added 22 HP @ 6,000 RPM)
-Then I went back and used the OP's Howards cam on a 350 and a 383 and both DO clear 470 HP with a good single plane. I was wrong. You guys were right. Totally possible to clear 470 HP @ the crank with that cam with AFR 195cc heads on a 355 or a 383 with a single plane (that 15-20 HP loss to a dual plain at peak RPM hurts, and makes it pretty unlikely according to a sim, anyway. Thanks for keeping me honest!



Adam

NewbVetteGuy

I am in agreement now. ResDoggie had another .3 CR and a better cam than the ones I tested with yesterday, AND that single plane intake. (I was only modeling a "high flow" dual plane yesterday. I can now clear 470 HP in the sim with similar 355 combos and my simulated curve in the dyno sim looks like ResDoggie's actual RW dyno results, although the sim has the entire curve moved about 200 RPM higher than the actual dyno results.


Adam

jb78L-82

Excellent Adam! We are making progress!

You are coming around to the reality that 355's with the right combos of parts especially roller cams of moderate duration, AFR heads and 10+ compression can pretty much post strong 383 like numbers with not much effort. In fact, Redoggie's 355 easily out Tq's and HP's pretty much most crate 383's as well as 383's with less than optimal parts and lower compression in the 9's.........28 cubes in todays world with optimised roller cams and aluminum cylinder heads just is not that much....in terms of useable street power anymore, which is what I have been saying for a long time now, after my personal experience with my 355 with AFR's.

REELAV8R

Hey Adam I would be interested in how putting a 750 CFM or greater carb on that combo might come out. 650 sounds restrictive to me in the upper RPM range, maybe not on a 355?, I would be interested to see if your software showed any difference.

If I run a CFM calculator with a single plane @ 100% VE ( I know unlikely) it comes up with greater than 650 CFM requirement for a 355 @ 6000 RPM.

NewbVetteGuy

I didn't need to come around to that reality. I've never doubted that a good 350 /355 can post good numbers.
-But if you're buying a new rotating assembly, you can spend essentially the same money and build a 383 that will make +30 - +40 ft lbs everywhere. That's a different issue than whether a 350 / 355 modern build today can produce the #'s of 383s from the 1990s, though.

NewbVetteGuy

-I was using 650 CFM because I think ResDoggie was using a 650 CFM carb. (The L82 Qjets are 850 CFM, right?)

For this kind of thing, I think PipeMax is a way better and more trustworthy tool, but I can put it into DDyno 2003 real quick because I still have it open.
-I had a calculation for determining how much airflow was required for a given cubic inches and RPM combo for a throttle body- and I'd like to think that that same calculation works for carb sizing, but I'm not sure... I'll see if I can find it.

Testing a 383 with an aggressive hydraulic roller lobe (my Mike Jones), AFR 195 heads, 10.2:1 CR, a single plain intake and 1 3/4" headers with full exhaust, and 650 CFM: 493 hp @ 6,000 RPM 485 HP @ 6,500.
850 CFM: 505 HP @ 6,000 RPM and 500 @ 6,500 RPM.
-So yes, the 650 CFM Carb definitely choking it at high RPMs.

Adam

suprspooky

Lots of good real world info here for the AFR 180/195's, thanks to all. I see a set of 195's in the near future going into my 355 SBC (18' 70's era Jet Boat) and maybe a Roller if budget allows (I originally built it back in the late 80's, General Kinetics flat tappet).