well im putting off the 4.3 tt swap for another year.so im gonna build another 3.1.now my last motor was going deep into the 12's with the stock cam,and iron heads.on this new engine im droping on some canted valve aluminum heads.now i only have a few choices for a cam.and ive really never understood how to pick a cam for a turbo motor.
so maybe u guys can lend me a lil advice.
heres what ive found so far
Hydraulic Flat Tappet, Advertised Duration 278/ 288, Lift .420/ .443, GM, 2.8/ 3.1L 110* lobe speration - 1,000-4,200 is what they say the cam is good for,now this cam says its computer compatable.
then i found this comp cams cam
Hydraulic Flat Tappet, Advertised Duration 260/ 260, Lift .440/ .452, Chevy, V6
also a 110* lobe seperation cam.supposedly not computer compatable(though its smaller then the first cam but has a higher power band)
and last but not least is another comp cams cam
Hydraulic Flat Tappet, Advertised Duration 272/ 284, Lift .454/ .480, Chevy, V6 this is listed as 2,000-5,500 rpm with a 112* lobe seperation also listed as non computer cam.but what i dont get is the 2 non cc cams are smaller then the first,only with more lift and the third has more lobe seperation.

any of u guys see a problem with using any of the non cc cams in the computer controlled car,and which one do u guys think would be best for a turbo engine

 

well i said **** it and just called up crane cams.they took all the specs on my motor,and are gonna take the time to see if they offer a cam suited to my needs.if not there gonna do a custom grind for me.more then likely it's gonna be a custom grind.im just hoping there not gonna hammer me on the price

 

Be careful when comparing cams using advertised duration. They can be measured at different points. The first cam is a good example of this. The duration is advertised to be bigger then the others when in fact it is a smaller cam. Only use .050" measurements for duration.

I wouldn't use any of the cams you have listed. See what Crane says. If they are anything like Comp Cams they will be all over the place. All of the cames you listed seem like they have too much exhaust duration for a "normal" turbo cam.

I use a 216* I/E, 110* LSA (Crane calls it a non-computer cam). It works fine with the GM 730 ECM after tuning. I always use non-computer cams with computers because they always seem better for making HP.

 

one of the guys from crane actually called me back today to get more specs on my engine,mainly my sheetmetal manifold& cyl head flow numbers since i didnt have them off hand when i spoke to them the other day.i do have to say ive dealt with comp cams before and crane is going so much further to make sure im getting the right cam for my setup

 

How about giving us more info on the engine so maybe we can throw you better info.

Bore/stroke
Heads: valve size, chamber volume and flow numbers if you have them
Intake: type, runner cross section, plenum volume (total volume), runner length, taper…
Exhaust details
Transmission/stall
Rear gears
Car weight
Intended power band
How much boost…

FWIW, I forgot what crane’s deal is, but with comp a custom cam doesn’t cost anymore then a shelf grind, it just takes 2 days to ship instead of one and isn’t returnable after they grind it.

 

Might want to look into a custom ground cam with like 120* LSA, and negative overlap. Small duration @.050 as well. like a 220/205* or something.

Vizard listed a sweet cam with specs like this for a tubo SBC motor. Scarily similar cam setup to the LS7 (as far as the huge LSA, negative overlap, etc).

 

3.1L with .030 overbore
BORE = 3.530
STOKE = 3.310
CR = 8.9-1

Heads are ported gen 2 aluminum canted valve heads
25 cc chambers
1.72 intake valve
1.42 (may be wrong ex valve)
they flowed just over 230 cfm @ .500 lift (stock iron heads flow about 163 cfm at the same lift)
intake is of a sheet metal design with aprox a 5 inch runner,and small plenum (cant give exact specs cause were still in the planing/design stages)

ex system is a single 3 inch no cat with with spintech muffler(runs in stock location)

trans = 700r4/2,800-3,000 stall lockup
rear gears = 4:10 atm but may swap back out to 3:42 or 3;73's due to turbo lag in first gear.run a 26x9x15 slick
weight is about 3,100#'s
engine being built to spin to around 8k(dosent have to rev that high though)
t-61 .84 hotside
7-12 psi on the street and 18-21 psi at the track on race gas

car is street driven ALOT,almost everyday

that shoudl just about cover everything,im still waiting to hear back from crane again,but shoudl only be a few more days,but maybe u guys could give me some suggestions anyway,and i can compare them to what crane comes up with

 

manifolds, headers??? any pics of the hot side plumbing (port to turbo)?

 

pace setter headers,to custom y pipe that comes out infront of the engine,(runs under kmember )2.5 inch) sorry no pics yet of the new setup

 

Wow, ok, a lot of conflicting numbers and you haven’t aswered things like the intended powerband or a lot of what would be useful to answer the question. I’ll do a little guessing based on parts listings…

First, I believe a .030” over 3.1 should be 3.540”.

Second, and I don’t mean this to sound insulting or anything, but I _really_ have a hard time believing 230cfm @ .500” through a 1.72” valve into a 3.5” bore… That’s about equivalent to around 320cfm through a typical 2.02” SBC valve into a 4” bore, which is barely within the relm of realtiy for anything besides the biggest of race heads with serious port jobs and big $$$ sunk into them, and more likely we’d be talking low valve angle heads, with bigger valves and non standard port patterns, and then you’d be looking for something that flows around 340 @ .500”… Neither of those heads which would make for a drivable combination on the street or at all work with the converter that you suggest, and would be largely dead below about 4500rpm.

Having said that, I’m going to assume that that you’ve got well ported, reasonable sized heads with an exhaust flow around 80% of your intake flow at similar lifts (if you really have an intake flow above around 180cfm @ .500” then the rest of this combination is sadly mismatched and should be seriously rethought before you mess with the rest of this), and with the rest of my guessing based on that converter, if it’s matched up to the engine we’re probably looking at something with a torque peak between 3-3500rpm and a hp peak between about 5-5500rpm.

What I’m reading in your description sounds like a set of normal headers with normal outlets and then hot side piping basically making a 180 and then back up to wherever the turbo is sitting. Not to start and argument here with people about this, but in general, I feel that manifolds or tight tubular setups are the most efficient, getting the greatest amount of heat/energy to the turbine, followed by the tubular headers and ending at a rear mount setup. What I’m hearing from you is a lot like some of the truck rear mount setups (that usually mount the turbo after the y – pipe, under the cab. If that is the case then I suspect that your hot side is a bit on the large side for good spooling on that setup.

All that being said, again, making some guesses, I’d shoot for around 218/220 @ .050” and 112LSA, that will be about the limit for this setup, it will really want more converter (around 4000rpm), and I’d consider going with a little more on the exhaust side if the exhaust is really like I’m imagining it. If streetablility is really an issue, I’ll look at something smaller, more like maybe 210/214/112. A greater LSA will give it better response to the boost, smoother idle and a little more top end, but will also make less midrange and make it more sluggish off the line with the tight converter, the tighter LSA will get it off the line faster/harder.

Actual, hard numbers will rely on what cam grinder you end up going with, what series lobes, and what lift will your assembly tolerate and give you the lifespan you want. Like that max recommendation using Comp XE roller lobes you’ll be stuck with either 218/218 or 218/224, the smaller the exhaust volume from the exhaust port-turbine, the tighter the turbine side, and maybe throw in some heat wrap… the more I would lean towards the 218/218 side and vice versa.

Honestly, if it was my car I’d probably better define what I wanted out of it, nail down the combination tighter and go with a different turbo setup and then reexamine the whole deal.

Anyone want to throw out details what kinds of cams have the 60* V6 guys been having good luck with and for what?

 

theres a flow sheet for the stock heads,ill try to get the flow sheet i have for mine that have been ported scanned,u have to remeber these arent reg heads,they are canted valve heads

 

Honestly I should be taking advice from you, since your v6 is faster than my v8 but anyway. From everything i've been reading about boosted (turbo mostly) engines overlap is bad. "if the barn doors are open the horses are getting out" However this is not necessarily true. Supposedly at peak boost the pressure inside the exhaust manifold, between the head and the turbo, can reach up to twice that of the compressor(boost) side. but this depends on turbo sizing and distance from the cyl head. as for the lift, the duration or lift @ .050 is more important than total lift. while total does help, all the #'s i've looked @ .050 lift is the main area of consideration, especially since the overlap is almost eliminated compared to a N/A high HP engine. Personally I would go with the custom ground cam b/c they have engineers and 'professionals' doing the math. not to mention one of the cams you listed made peak power under 4000 rpm and you want it to spin to 8k. this would seem a bit contradictory, even though it will be a daily driver.
like I said, this is based off of what I've read over the last month. trying to learn how to build my engine. so i guess it's all theoretical. I'm curious what would be considered the 'right' cam though b/c the computer controlled deal does seem to be avoided by proper tuning.

 

actually when the ypipe comes off the headers its foward facing(custom y pipe)it comes under the k-member and makes a 90* bend upwards to the turbo.
im buildin g this thing to take upto 8k rpms,though im really not sure how high i will spin it,i talked with crane again and they asked what was keeping me from going with a mechanical/mechanical roller cam.which after speaking with them i just may do,cause im really loking to get about .560+ lift were these heads flow exceptionally well.ive been rethinking my manifold and am prolly gonna shoot for a slightly longer runner.stock runner lenght is just over 14 inches,and my plan is to aim for about a 7 inch long runner.
as far as the .84 hot side i dont think it will be a problem with the poorer flowing heads and 4:10 gears ive got full boost in first just over 3,200 rpms,with the .63 hotside.

so with the lil looser converter and the better flowing heads/and less rear gear im quessing ill be looking about the same spool time,possibly a lil better.

one other thing i may do is some combustion chamber mods to unshroud the valves a lil better at low lift,though i have to see just how much further i can mill the heads to make up for the cc loss ill have if i mod the chambers to keep the base cr around 8.9-1

 

This is pretty much always the case… you never want enough overlap to hurt scavenging/boost, but the fact is that as the intended rpm range goes up so does the amount of overlap that can be tolerated without any reversion issues. It just doesn’t go up as fast with a turbo because of back pressure issues.

He, do a search for other similar threads that I’ve responded to… you can have fun playing games with these “professionals,” or you can even write yourself a script and try it a few days in a row and you’ll get different answers each day, and you can predict how the answers will go depending on what manufacturer you’re talking to (I’ve elaborated on this before, I’m not going to waste space here).

Yea, headman V8 headers actually have slightly forward facing collectors. Doesn’t make a difference, you have feet more pipe then you need, many square feet more surface area to give off heat/loose energy, and much more volume then you need… My recommendations would be different with a different setup.

That doesn’t really answer the question, and the pics of the heads, well they help your original point, but splayed valves and all… yep, you might have that much airflow, and if you do YOU DEFINITLY do not have a head compatible with being a daily driver.

With that kind of port flow on that small an engine you’re talking about something that probably flows enough to turn 8500-9500rpm, but anything built to make power and actually run up there is going to be unhappy down low. If you doubt that drive a first generation S2000, they make power up there and are built to rev that high, they’re worthless below about 5-6000rpm and are hard for most drivers to drive fast. Usually you’re talking about a 7500rpm or higher clutch dump to get the thing off the line, and in your case you’d need a 5-6000rpm converter to do this well.

If you’re really going to turn the rpms we’re talking about then you don’t have a real choice. HR cams start getting tempermental in the mid 6xxx RPM range, and they’ll never be happy in the >7kRPM range. Nutshell, a SR with 7-11* more duration will have the same characteristics as an HR, mostly because the soid/mechanical lifter has to overcome whatever the lash is set at and other mechanical losses.

Please figure out what you really want out of this setup and stick to it. Right now I’m seeing massive heads (high rpm), longer intake runners (lower rpm), worries about shrouded valves (if they flowed what you said then they’re not shrowded, I suspect that they’re not shrouded at all considering the canted angles…

It may be cool to use exhotic parts... but if the rest of what is there doen't work/match with it you'll just end up with something that doesn't make the the power it should or last as long as it should

 

the valves arent shrouded much at all,but it looks like a lil improvement could be made with some chamber mods.
as far as cam/intake nothing is solid yet,alls i have for a manifold is the base of it,no runners or plenum yet,its gonna come down to what i can fit under the hood,im having alot fo trouble in figuring out runner lenght,few ppl told me that 5 inch runners would be to short.thats why i was thinking maybe an extra 2 inches would help.atleats for non boost street driving.
the heads arent massive they are gm production heads that flow 211cfm@.500 lift from the factory,and the only porting done was some bowl work and cleanup work(picked up the flow a ton)
thats why i dont get why u are saying the heads wont be any good below 4k rpms

the main reason for going to the sheetmetal manifold is cause i cant use a production manifold on a rwd engine without swaping to dis,for the amoutn of work id rather just build a manifold thats better then the factory peice so i can run the dizzy and keep my exsisting ecm/wiring harness