im at the point now where all my other pieces have been chosen.. the only variable left is what compression im going to run and the cam... im still learning about boost, but i know i need to work harder on making the exhaust flow out... and i probly want less overlap so that the fresh intake charge doesnt go out the exhaust... and this cam has to be FI compatible (even if its just bearly)... im from the N/A carbed world, so theres alot i donno about choosing a cam for this motor... reccomendations and websites with info would be great...

the motor:

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the car is daily driven, however i am a kind of nut and dont mind driving somthing fairly crazy on the street... manuals make it alot easier to live with then autos... i just need to be sure that i can make my EFI run, with this cam...
a off the shelf cam thats close would be great, but im willing to pay the $50 for a custom grind IF ITS NEEDED....

if anyone has a solid roller blower cam, PM me with info.. i would love to find one used cheap...

 

ok, i'll rephase in the form of a question.


what cam for my motor? can you tell me your reasoning behind the choice too? mostly i need LSA and duration.. i already know im looking in the .575 -.600 lift range (1.5:1 rockers)

 

How about more details…

Intended use, intended power band, power goals, head flow numbers, exhaust…

 

lil on the extreme side of daily driver...

6500 redline... id like to shift just before 6k though.

no real power goals, but id be disappointed if i wasnt deep into the 11s when it hooks.... id like to be able to do low 12s on street tires... mostly just hang with LS1s... no real number in mind.. this car is mostly my toy....

at some point this car will be in few open road races like silver state.... but thats later..

numbers i have:
exhaust is hooker longtubes... elec cutouts behind the headers, rest of exhaust goes into a Y pipe and then to a catback.. at the track or when i want to punch it, i'll open the electric cutouts, so it should be pretty fre flowing... in the mean time, it will have some restriction since im running a full and reasonable sounding exhaust..


edit:
when i say "hang with LS1s" i mean hang with the Cammed or 125 shot cars... not stock low 13 cars.

 

I'd keep the duration real mild and the LSA pretty wide. My 142 is almost maxed-out shoving only 5 PSI through a 383 with a Comp Cams 268XE ground on a wider 114* LSA (224/230 @ .050; Lift around .500/.510 with 1.6 rockers). On the intake side I'd look for something that will have lift right around .500 to take advantage of your head's flow capability in that range.

Maybe go with the same cam I used or the slightly milder XE262-14 along with 1.6 rockers.

The XEs with the wider LSA are not custom grinds- they are the XE cams made for TPI engines. I happened to stumble on them in their catalog and thought....... Hmmmm, that would probably make a good blower cam. It did.

Keep compression at 8.5:1 or less with iron heads (below 9:1 with aluminum) and don't expect to be pushing a lot of boost with that little blower. You'll probably run out of pulleys before you see anything like 6 PSI, although I have not played with the M-112 myself.

 

my past experiance has told me that i want to go past that high flow point and back so that i hit that part twice... but thats flat tappet n/a stuff... should i try to make the peak lift right at that point the roller cam holds it there?


cool... but they're solid roller right? or will i have to get one custom made with thoes specs thats a solid roller... probly add a lil to the lift to account for valve lash...


i was planning on about 8:1 - 8.5:1 i dont want to really go too low since the bypass is open when im off boost


as for boost, the lil M112 is more efficent then the older roots blowers, so im expecting a lil higher... crossfire83TA (aka silverback) thinks i can expect around 10lbs of boost off of a 2:1 ratio.... and i can easily go as high as 2.33:1 before im overdriving the blower by eatons specs...... and from what ive been reading, i can overdrive it quite a bit past their posted specs and it just gets more and more efficent..

if im not happy with the boost its making, i'll probly port the sound reducing lugs out of the bottom of the case and make it flow more... it would be alot louder, but more boost...



so you're saying a wider lobe seperation would work and let me use a cam like the XR280R?? or should i go a lil smaller with a XR274R?three quarters of the way down this page for the specs

 

drat! i lost my orignal reply... i hate when that happens

what do you think of the XR280R on a wider LSA?
are the wider solid roller cams still not custom grinds?


i expect compression around 8:1-8.5:1.. i dont want to go lower because it has to run on the cam when the blower is bypassed at part throttle.

im not worried about making boost anymore, the M112 is more efficent then conventional roots blowers.

 

i'd go 8.5-9.0 with iron heads, and about 9.0 with aluminum. 8.0 - 8.5 is too low in my opinion... i know a guy with a stock LT1 (i BELIEVE its 10.5:1 stock) with an ATI D2 blower at 10 psi and has no detonation, if you go that low on compression your gonna have some serious lag till it makes some boost

 

also doesn't that blower make 8 psi on lightenings stock? and a lightening is a 5.4, so on a 400 cid motor with stock pullies (stock ratio anyways) i would expect around 5 psi, and you could definately get around 10 with smaller pullies

 

I picked a 220/230@.050 .460/.480 w/ 1.5's on a 114 lsa. with 1.6's i guess it would be .490/510 right? that's on my 8.3:1 355 w/ trick flow,. flat tappet.

 

Well…

You're not going to like my answer.

Take those stinking heads apart and get a monkey that knows how to work a grinder to work those exhaust ports. I'd like to see at least 75% of the intake flow on the exhaust on an NA engine… >85% for a blower. You're at about 66% now. Also, don't just hog the ports out… that's no good… you'll want to keep the throat crossection somewhere in the 60% of the bowl or rest of the port range to better take advantage of the scavenging those long tubes can give you. FWIW, I did a set of vortec heads for a friend's dually (which will eventually be blown) last summer. With 1.5" exhaust valves I got over 200cfm everywhere over .400" lift, topping out at just over 93% of the intake flow (the 8.3:1 350 NA it put over 420hp to the ground through a long bead dually chassis and all it's losses he's very happy with my work and recommendations on the engine).

Assuming that you don't do that (if you do ask again) you'll need something like an XE HR 218/230/114 to meet the rest of your goals (admittedly, 6500rpm will be on the far side of what this thing will want to rev). As a matter of fact, with good tuning and driving you should be able to see high 10's with under 10psi boost… (FWIW, my brother's 302/M90 car is running 120mph with an old tech Lunati 218/228/112, you're talking 1/3 more engine and almost as much more blower to run the same times… you should be able to do it with a stock TPI cam)

Of course, besides the power it will be a dead boring cam… it will pretty much idle like a stocker in that engine and your shift points will be around 6000rpm, if that. The flip side of this is that it will be dead simple to tune and live with. A street SR with roughly similar numbers but 6-9* more duration on both the intake and exhaust will run similarly and make 10-25 more hp.

I suspect that you'll choose something somewhat bigger to avoid being accused of running a wimpy cam. One or 2 steps up in the XE blower grinds will keep you happy with your 400, give you some lope and still be tame enough not to cause any major hassles.

Get a little more realistic and I'll go digging through the SR cam lobes available to see if there's anything I like…

 

looking at thoes numbers, would you say he just polished the exhaust ports? because looking at them(the ports themselves), i kinda think he just made them look pretty and didnt do too much to them... when i bought them, they were already "ported".. i thought the bowl work looked a lil sloppy too, but was just going to leave em alone..



ok, now when you say high 10s, are you saying this assuming i take apart the heads and go over them again, or are you saying if i leave them alone, they'll do that?
because high 10s on a streetcar is great... fuggin great.. id be more then happy just to leave the heads alone and bolt them on if thats the case. if thats the case, screw big cam, i'll stick to somthing smaller.. i may love the nasty rumpity rump, but it would be cool to be a sleeper....




bah. if what you're saying is right, im better off sticking to a smaller cam that will help down low.. i just hate thinking i would get more power if i had just gotten that bigger cam..
if its helping everywhere, a smaller cam would be just fine with me.. im just used to having to goto big cams for big power.. this is my first "power adder" motor..


what do you mean by more realistic?

btw, i'll be ordering this cam 2weeks from the 15th.. paycheck after next. :lala:

 

Looking at those numbers I don't know what the hell he did (I thought that you originally said you did it?)… They are lower then I've seen a set of box stock iron eagles flow on the exhaust side and only slightly better on the intake side.

I'd be afraid that if either end has had any cutting done and those were the flow numbers that you ended up with that the port contours were actually messed up to the point that it would be difficult to fix

I'm saying that if you can stick a cam in there that will compensate for those exhaust ports enough that you should be able to do it with those heads as they sit.

Like I said, my brother's car has run 11.5@120 with ¼ the ci and an M90 with a fairly small cam, heads that don't flow much better and a crappy exhaust (the only reason that it hasn't gone faster is that it was running out of fuel, spinning off the line, had tuning issues and has been in the body shop once all that was fixed so it hasn't been run again to get things tuned right). If you can't do better with many more cubes, a bigger blower, better tranny, better suspension, a chassis that will fit more then a 9x26" tire… then your doing something wrong.

You will make more HP up top with a bigger cam, but I don't think that you'll have a happier engine… With power adders you pick a cam that helps with your weak points and then doesn't mess anything else up and you can make good power. The thing is that running a little more boost will make more power then all the cam tweaking in the world. That and I'm a big fan of a sleeper with enough low end to lift the front hoops at will…

bad choice of words… more like "on the same page WRT to what is possible so we could discuss what you really want within that context"

Have you talked to any cam grinders? I'd make a point of the crappy heads to them and see what they say. I'd bet that if they listen to what you want out of it with the exception of the max rpm you listed they'll spec something similar… If they hear the 6500 then they'll recommend something larger. Personally, I'd keep the cam on the small side and keep the compression low (the small cam will play nicer with the low compression off boost), and then "do the work" with boost. Although really I'd rip those heads apart and start grinding shooting for the 90% mark and then end up with something in the 220-230 @.050" range on both the intake and exhaust with roughly a 112-114 LSA. That will probably end up giving you more usable rpm, more power and even a tamer idle. At that point you'd have to start tweaking the M112 to keep up but if you could get it to live at about 18-19Krpm/6000engine rpm/~10psi boost you could be over the 800 hp range in something that would idle like a stocker (real world most people don't push these things nearly this far and you'll live with reasonable rpms and 600hp at the crank… still plenty to run the times you want). Clean up the heads enough and you'll have bigger problems with the blower keeping up.

Again, remember that most of the numbers I'm throwing around are for an HR, if you're really going with the SR the duration #'s will be 6-9* more for the same effect.

 

Heh… I keep having the same thought… fix the heads, go real tame with the cam (maybe something like the lingenfelter 219 or smaller) and throw the thing in a truck (my truck ).

BTW, as a side note, this is a "if you get everything right" scenario, if you monkey it up you're just as likely to end up with a 13 second car… with my unusually good luck with these things I bet that I could run low 10's or maybe even high 9's with this combination (I wonder how many tranny's and rears I would break…).

 

hmm.. i think im going to leave the heads alone, and i'll just swap out heads later... looking at them, i dont think i want to even try to cleanup them anymore... everything looks like is been messed with alot, and the only thing inthere im wiling to touch would be some better work on the bowls and a lil tiny bit on the exhaust... not enough for me to take the heads apart for..... i might as well just keep them on, and if they do suck that bad, i'll put some better alum heads later on.

i realize you're saying "potential to run 10s"... not "i will run 10s".. id be happy to be in the 11s.. i mean the rest of the car needs work to go that fast too... walbro 255 FP is the only fuel upgrade, so i can only make what that will support for now... im not running a sticky tire until i get the 9" under there, and i havent even bought one yet.... the chassis needs a rollbar put in before i can even run nearly that fast... (remember, convertible)..

i usually dont have the luck of getting it all right the first time out, but im more like one of thoes guys who runs a lil faster everytime out until hes going as fast as the car will go for what he has....
then i add somthing big and screw it all up again.

with the help of some other people, ive had one car in the high 11s before, so im not totally blind here, but ive still got alot to go with this setup before its really running upto its full potential.

as far as the "ported by me" goes, i started it, did one intake and got kicked out of doing it in the garage by my roomates... work makes me only be able to do it at late evening.... so i gave it to some guy that suppost to know what hes doing... he ported the rest (including "redoing" what im done... proud to say thats still the best looking one IMO) and he put the heads back together....

looking online though.. somthing seems fishy with the numbers he gave me... o_O.. i think he screwed me over.... *sigh*

im not really going to get worried over it.... as long as she makes enough power to keep me entertained the next two years, i'll be happy... after that, i'll probly get a coupe stepup to a aftermarket block, start making my open road race car.... (thats the plan atleast)


anyhoo as far as the cam, yes i will be sticking to a solid roller... mostly because i want to run a roller and i already have everything but the cam..

 

Dude- the XE cams I'm referencing are flat tappet hydraulics. Roller cams you're on your own- I don't use them.

Yes, if you can go beyond the max-flow lift point by a bit so it spends more time there it's probably going to make more power. With a flat tappet cam of mild duration such a I referenced you're going to have a difficult time getting that much lift, even with 1.6 rockers to spend much time there. Again, a roller cam would be a different story.

Having never used an Eaton blower before I can't say how much boost you're going to see in actual running conditions on your 400 but my slightly larger 142 is pulleyed at a 2.28:1 ratio now and only makes about 5 PSI on my 383. I thought the Eaton could be pulleyed WAY up compared to my old-tech 142. In the neighborhood of 2.8:1. No?

Don't go ape-$hit with compression. If I had the choice of going 1/2 point too low on compression or living on the "bleeding edge" of detonation under boost I'd take lower compression ANY DAY. Detonation is so destructive in a blower motor you will NOT like what happens if you guess wrong.

I run 8.7:1 right now in my motor with aluminum heads. Bypass valve or not I don't see ANY boost until I'm almost wide open. In short, I'm running around town basically like any N/A motor. It's not a slug. Going overboard with cam choice is FAR FAR FAR more likely to make it a "pig" than going a smidge conservative on the compression.