i said before the difference in a good cam and the best cam might be 10 hp but put a bad cam in and you will loose 30-40 hp. its about the whole combo and not just a cam or a head. i hear no talk about the nailhead intake manifold. get a nailhead head flowing 260 cfm and then put the intake manifold on it and flow it again, see what happens or ask Bob he will tell you. i said years ago the intake is a big bottle neck even if we have high flowing heads. its about the combo and detail, dont get hung up on one thing when your building a nailhead street car. f85 what do you think a high flow alum single 4 barrel would do for us ?
Sorry to side track but you did bring up intakes, has anyone tried to make adapters to run a sbf intake on a N/H? Even one of these aftermarket intakes adapted should flow better than the N/H intake! That is one of my many backburner projects I want to eventually do unless someone else beats me to it! There are basically 3 different widths to chose from if you don't count the the Modified(which would probably be to wide because it has a taller deck height). So that brings us to the Windsor, Cleveland and the 289/302 shorter deck intake if more room is needed for port transition which are 9.500", 9.200" and 8.206" respectively. I choose the above intakes because of the closer intake port layout as well as because the Ford engine blocks are passenger side forward like the N/H blocks are. And plus everything else is no where even close to being adaptable! I think the conversion for a flat intake adapter would be the taller deck height of the engine being adapted to minus the deck height the intake is from equals the thickness of the adapter? Don't quote me on that though, lol. So a N/H with a DH of 10" - 9.500" would be 1/2" thick they would need to be? Or is it half that, I can't recall right now. Anyway, to make an N/H adapter the shorter deck intake would probably be a better fit because the bottom of the "V" on the Ford intake would have to fit in between the inside of N/H ports so the adapter could be milled on a 45* angle to mount the Ford intake.(I hope I made that somewhat clear, hard to explain) Derek
That aspect didn't get by me, I still stand by my comments. You can assume that when I'm referring to induction that I'm referring to the entire thing, even if it isn't spelled out. I chose not to comment on intakes due to the fact that the vast majority of consumers don't pay to have the entire system flowed and that Nail users could be using either stock or modified intakes, but the same things still happen regardless. Dyno and track numbers still improve when the heads do, even when they surpass the intake's. I left some details out to try to keep the commentary from getting out of hand. I'm fully aware of the rest of the induction package and it's influence, from having designed, built, flowed parts and driven these things. I'm attempting to comment in a way that I feel people will learn from and apply, instead of participating smoothly with dialog coming from a consumer perspective. It won't hurt my feelings one bit if you disagree or ignore my perspective. Definitely many cams lose 30-40 hp, and that the pieces don't fit the puzzle... one of the most important aspects being the induction system and how it supplies the cylinder. Another aspect is the header or scavenge and whether it coincides with the package. One reason wide LSA and low overlap tests favorably in some circumstances is because eliminating scavenge altogether is predictable vs an incorrect or nonexistent header could be detrimental. The entire competitive motorsports industry embraces the use of overlap. Mainstream cam Co's (such as Comp) err towards ease of tuning, and in cams that have much more 'thump'...are more intended for sound, thus getting them off the hook. Obviously a 'one size fits all' profile isn't going to work when every engine from every family has different cylinder geometry and induction physics. My comments that may have rubbed you the wrong way weren't intended to be personal, I was dis-including everyone's motives. My perspective is this...if I'm going to make a change, it's going to be a big one. I have the tools to get it close to as good as it's going to be off the bat. Most consumers aren't going to go down the path of dyno or track testing to swap 10hp around, therefore using sims or a professional they trust saves incredible time and expense. Taking a guess with sims and a belief that the cam dictates the behavior more than the induction systems based on what camshaft nomenclature or magazine articles supported by those same Co's state is probably safe, but there's a reason people are exceeding the mainstream competitively, getting paid to do so for others, or even making products for the aftermarket. It's literally impossible to talk about the effect and behavior of camshafts without addressing the fact that all of the things around it affect those interpretations, including the induction and exhaust systems. Every comment or question posed so far has been a valid contribution to the thread, even if there's been replies that slightly tweak the perspective. The same things happen with other engines too. The more you learn about them the more you see that they operate from the same rules.
You'd have to start with an intake with the appropriate CSA for the intended power level. It would definitely be a gift to the community to see some effort towards performance, now that more people are seeing the possibility of a 500hp head within reach. Comments on smooth idle... A Qjet vs a larger primary Holley with equivalent max cfm rating can tone down the cam's idle and improve vacuum 1.5" or so, on a heavy overlap cam similar in specs to the ones being discussed here. Side by side duplicate engines give the impression of 10* less intake duration. Both in the high 12's at the strip. A 'no-loss' exhaust system, or 180* long branch tri-y header of appropriate dimensions and on the smallish diameter will markedly smooth the idle over a 4-1 header (always having an out-of-sequence cylinder on each bank). Joining the duals to a large single will 'hide' 10-15* of cam. An exhaust as described above, along with a port on the smallish side (high velocity), can have a tremendous enough smoothing to the idle to get a 270* @ .050" cam to sound like a 230* @ .050".
Hey, Joe. I'm running an SP 400 (converted to Chevy pump) a B&M shift kit and Dacco 3,200-3,500 stall with trans cooler
Hi Derek, I have had a 1x4 on my bench in my garage for a year. I just have to finish mikes heads and do some final adjustments on the intake. Then it's going straight to gsgtx for some testing. It should be interesting
Cool, is it going to be flow tested? Would be awesome if it could keep up with the head's ported by you intake port flow! I always enjoy reading your porting results and about drinking beer in your little porting shed working on a set of N/H heads.(that was you right?) You were the one that posted the silicone mold of the N/H exhaust port as well IIRC. Good stuff, thanks for sharing all that. You were gone for a while, glad you're back posting about your N/H work. Derek
But what about the exhaust side? With exhaust flows between 65-70% of the intake flow, what cam profiles help to improve overall power? Split pattern cams help, but does extra increased exhaust duration help even more, or is there a trade-off. For example, comparing a 224-230 profile to a 224-236. The sims I've done show increased higher rpm power with only a very slight loss in the low end. I'd contribute that to better intake breathing due to extra overlap, and a slight loss in low end due to the exhaust valve opening earlier at the end of the power stroke. What cam characteristics are beneficial to an exhaust-choked NH? Understandably, tuned headers will help scavenging, but what about stock manifolds or available 1-5?8" primary T/A Performance headers?
Or better yet, custom made headers with 1 3/4" or 1 7/8" tubes with a 3" or 3 1/2" collector??? Length to be determined by painting the ends of the tubes??? With an intake that flows 250 x 65% = 162.5 or at 70% = 175 which is at the top limits for exhaust porting with the center cylinders being the hardest to achieve these goals. Many questions & testing which is beyond the norm for all except a very few. Tom T.
update. was trying to set rev limiter with old cam pulled good to 6200 [wow]. new cam in and tried to set rev limit to 6000 but went off at 5500 with new cam. ok new cam in, at idle picked up 1/2 to 1 lb of vacume. better throttle response and low end. even air going threw carb sounds deeper and louder. mid range to 5500 a little better. going reset rev limit and see how it pulls to 6000 rpms, but not going to go past 6000 anymore. am happy now for a little while anyways lol. will update on 5500-6000 shortly.
what a difference a cam makes. tires spin at 15 mph now and pulls up top too, might be engine breaking in more too. anyways do nail heads have to have a lot of extra exhaust duration, no not at all. next thing would going from 9.25 compression to 10.0 make any noticeable difference ? cranking compression is now 165 psi with 10.0 would bring it to 180 psi.
An extra .75 in compression should give it a really nice bump in the low end. The traditional power increase curve would suggest 3-5% or so...but at full throttle and near the power peaks. The butt dyno suggests a much greater potential at part throttle and at the bottom end of a cam that is hypothetically soft off idle. You get overlap working good with headers and it reduces the need for more exhaust duration. It's easier to blow down a cylinder with some pull on it. Really, the benefit is to go beyond the need to 'just' evacuate the cylinder and use that pull to initiate the induction cycle. This is probably what you are beginning to see.
Comments made about testing presents an opportunity for dialog. I think there are plenty that can test the effects of their theories, whether originated from the mind only or aided by math sims to assist the process. The difficulty is justifying or paying for the time, whether on your own project or if you have the ability to test stuff but lack any direct benefit from doing so. Even the parts vendors don't do that much testing. People that are far ahead of others keep a certain amount of information proprietary. It's always serving some kind of business needs. So, it's not that many "can't" properly test things...it's more of a question of who will pay for the testing or what the motives might be. Once someone's happy with their project they tend to enjoy it for themselves, or offer it to their customers.
