Sir,

I have a few thousand questions I'd like to ask you . . . LOL !

Seriously, I need to "pick your brain" in spec'ing the correct cam for a 408 LQ9 stroker.

Like you, I am after torque in a daily-driver and need "facts", not "fluff".

When you respond, I'll be happy to supply you with any information you need, if I have it. And, if I don't have it, I will find it !

Thanks, in advance !

 

Find someone who is actually knowledgeable on gen 3/4 engines. Geoff at engine power systems or texas speed, speed inc etc.

 

Give me all your pertinent information and I can have one specced for you. Will need a complete build sheet (not just the motor!) as well as desired goals and characteristics you're looking for. I work in conjunction with Chris Straub, for reference.

 

I have a lot of technical questions, too. Is there any way I can give you a call. It's much easier than typing - LOL !

Thanks !

 

Go with a company that is up on latest ls cams and lobes. I would order from anyone I listed but you really need the entire combo laid out before asking to have one ground.

 

PM me.

 

Thanks for the tip . . . I've heard good things about Geoff at EPS !

 

Every cam company has a tech line and an online Cam request form. I prefer to get suggestions from the horses mouth.

It can be interesting to see what different manufactured recommend.

They are often very similar.

 

The problems I have been running into is that everyone seems to have a different opinion on how to spec my cam. They are all very good at "maximum power" cams, but it seems that powerful daily-driver cam specs give them problems, at least with my application and intended usage.

When I ask them about those differences among them, they either get "offended" or start "putting the other guys down". It leaves me in the position of not knowing who to trust and I don't like that, at all.

I wish there was an online calculator where you could plug in Bore, Stroke, Gasket specs, Head Flow CFM numbers, Desired RPM Range, Desired DCR ( not SCR ), and Fuel Octane . . .

It would then design the camshaft specs to achieve those goals and supply them to you. Then you pick a company to make it for you.

Notice that I did NOT have to supply Chamber cc or Piston cc specs ( no SCR supplied ) . . . I want the cam specs to be based on the Desired Dynamic Compression Ratio. Once that is done, the SCR needed to achieve the DCR, could be calculated with the Chamber cc and Piston cc adjusted, accordingly.

I don't have a good answer to this situation and appreciate your input.

 

Its called simulation programs. Good tools. Engine Analyzer, dynomation, etc. they tend to work well if you really have the right information at hand

Some of them other shops that sell custom grinds or whatnot only know max power stuff, because some of them have other knowledgable cam grinders spec it for them and they may just take it and dyno test a few, see which made most power and give it a cool fancy name.
I would trust people like Mike Jones from jonescams, bullet cams, Ed Curtis from flowtech, and even Bret Bauer who alot dont seem to like but hes done well for me, and then research truck forums for results of torquey setups. Those guys seem to run smaller cams often and could possibly find some good information.

 

Thanks for the input . . . I should have given some Spec's about the car and motor.

The car is a full-weight 2000 Z28 , A4 Automatic ( 4L60E - changing to 4L80E ), Rear End swap is also planned ( Looking at Strange S60 or 12-Bolt ), Weight with Driver, Iron Block, 4L80E and S60 should be just under 4000 lb. with A/C, Cruise Control, Power Steering, Power Brakes, etc.

Converter . . . As tight as possible for maximum MPG and "around town driving" , obviously a lock-up converter. I've been thinking a 2800 RPM "SS" Yank, or thereabouts.

Rear end gears are also going to be as "tall" ( not above 3.73, prefer under that ) as permitted by the combo . . . MPG

Performance goals are a minimum of 400 RWHP, corked up, no open exhaust . . . ET's in the mid-low 12's on street tires.

The MOTOR . . . ( The stock LS1 is "going bye-bye" ).

LQ9 stroker . . . 408 cid . . . 4.030" Bore . . . 4.000 Stroke

Heads . . . Cathedral port . . . 68-74 cc Chambers . . . ( Ported 317's (72cc), OR PRC 225cc As-Cast (68cc), OR AFR 205 , if a 74cc chamber is needed )

Pistons . . . Forged ( Flat-Tops w/-3cc reliefs OR -8cc Dish - OR DIFFERENT, Depending on "Required SCR" ) Static Compression is yet to be determined, since my goal is to target a DCR of 8.25 - 8.5:1 to avoid detonation on 93 Octane and to be able to run decent Spark Advance.

Desired RPM range . . . Idle to 6000 +/- RPM ( Broad flat torque curve over peak numbers ).

USAGE : This is a TRUE daily-driver, driven just as if you bought it brand-new from the Dealer, 50-60 miles per day, in city and interstate.

It needs to have decent MPG, be smooth and quiet, pass OBD-II Emissions Inspection ( no sniffer in NC ), and not buck, surge, or overheat in traffic.

I want to be a "Stealthy / Sleeper" car, to avoid problems from the Cops OR the Wife !

 

THIS is the EXACT point where the "party begins" with the various "Cam Guys" .

I have a target DCR of 8.25 to 8.5 to be safe on 93 Octane and to be able to run reasonable Spark Advance, without detonation.

QUESTION : IN MY APPLICATION, am I better off with an SCR of around 10:1 +/- vs. an SCR of 11:1 +/- , given that the DCR will NEVER be above 8.25 - 8.5 :1 , in terms of Cam Design and IVC point, RPM range, and Power output ???

That question is precisely where the problem starts, when talking to people, either about "off the shelf" or "custom" cams. Everyone has a different opinion about it.

 

Imo you dont need or want a crazy custom lobe design for this. You are focused on mileage and driveability so longevity in the valvetrain is what you are after.

Imo, 3.08 gear, 2800 stall is perfect for this. 10-10.5:1 is perfect. Sure ls can run higher comp but you arent looking to make big hp. A stock cammed 6.0 can make 450whp with large cam and 10's to 1 comp. ls3 based motors make 400 whp with just bolt ons at 10.5:1.

Keep it low for the 91-93 oct blends. Small cam in the 220 deg range or so, lazy lobe mid 500's lift. Will idle stockish and make power with good heads. Hell i bet a ls2 or ls3 cam would make your power goals with heads like ported 317's or afr 210's! You dont need alot to make that power in 400 cubes

You can also have a good full exhaust thats quiet and not restrictive so no worries there. Bullet muffler up front under car, after headers or just use cats, and run over axle into something like slp powerflo or ultraflo round mufflers with a good sized case.

I dont know why the cam guys are complicating this or trying to throw you a race cam

 

I think it may be because they are used to dealing with the "I want Lope", "I want it to sound Bad-Azz", "I want Dyno numbers" guys, both online and in their shops. That is not me, or my goals for my car.

30-plus years ago, I had "Bad-Azz" on the Street . . . 1970 Chevelle 454 w/ about 575 BHP ( Probably about 500 RWHP ), Solid Lifters, 850 cfm Holley Double Pump carb . . . I drove it on the Street and everybody KNEW it "meant business", from a good distance - LOL !

It ran low-11's ( through the mufflers ) with a 12-Bolt with 4.11 gears and a Turbo 400 with 3500 RPM B&M stall converter ( this was in the "pre-lockup converter" era ) and it got 6 MPG, taking it easy . . . STOMP it and you could watch the needle move on the Fuel Gauge.

That was THE and this is NOW . . . Times change and so did I !

My "target" is a MINIMUM of 400 RWHP, which should be EASY with 408 cubes. If there is MORE, fine, but I won't sacrifice longevity, driveability, stealth, or the ability to pass OBD-II.

 

Obd2 is just a scan of the ecm and the codes or mil lights can be turned off. You can pass that no issue with any mods

You wont have an issue with your goals. Also forgot to mention advanced induction may have something for you as well. Turbo guys also like some of the mild isky lobes. Theres options out there for you.

 

Naturally aspirated with no power-adders.

 

Why do I need higher Static Compression, if this is a lower RPM torque motor and the DCR will never exceed 8.5 :1 ? As SCR goes higher, the Intake Duration must also increase and IVC must occur later & later. As a result, "bottom end" is lost with the need for Lower Gears, Higher Stall Converter, etc.

My understanding of Valve Events, for my application, are :

IVO - Later is better

IVC - Earlier is better

EVO - Later is better

EVC - Early is better

A combination of later IVO and early EVC is a good thing.

A wider LSA is better. Negative Overlap is critical for Emissions.

Lift is best determined by the Head Flow numbers.

Duration is determined by the desired RPM range.

IVC determines the DCR.

What I don't understand is what makes an 11-11.5 SCR motor with a DCR of 8.5 is supposedly "better" than a 10-10.5 SCR motor with a DCR of 8.5, since the motor only "sees" the 8.5 DCR during operation and the motor will be used at or below a maximum of 6000 RPM ?

 

Because DCR is relevant only at very low rpm. It all goes out the window as port velocity goes up and the inertia of the intake column of air packs more into the cylinder with the help of the late IVC.
I second Orr's recommendation above to talk to Phil Odom at AI about a cam. He has more experience with the LSx motor combinations than all on this board combined. I'd be talking to them about ported GM heads too if you haven't already made that decision.

 

Do you have a LINK for AI ?

I haven't decided about the heads other than the will definitely be Cathedral ports, rather than L92/LS3 heads which have too much runner volume for my application.

The DCR info is very interesting. I've never heard about it only being relevant at lower engine RPM's ( any idea where the "cutoff" is for it to matter ? ). So, does that mean that the 93 Octane fuel will ever "see" the full SCR of 11:1 or more ?

 

http://advancedinduction.com/LSX/AiLSxMain.php

There's really no "cutoff" where the DCR number becomes irrelevant, but for a well-matched combo, it's generally around the torque peak.
I believe you're overthinking this. For the modern fastburn chambers you're talking about here, the timing required for best power is so low compared to old-school heads that for anything streetable like you're aiming for, as you continue to advance timing, you'll generally start losing power before detonation sets in with premium pump gas. With a nice tight quench, I wouldn't worry about anything under 11.0:1
You're going to be shocked at how easy it will be to exceed your power goals with a setup that won't even raise an eyebrow.

 

True . . . I know the "old school" SBC's and BBC's, but these LS motors are "unfamiliar territory" for me.

 

If you recall our discussion on the phone, I stated that the converter is critical in getting the performance you want out of your desired combination. A OD/Lock-up style transmission with a GOOD converter will not exhibit symptoms of that you're afraid of even with higher stall speeds. As soon as the converter locks it's "business as usual daily driver material". I don't think it's fair to say one converter is better than another necessarily just by brand, but it's hard to recommend anything without having the rest of the build established in stone first; right now you haven't done anything so you really aren't in a position to move. I certainly wouldn't be guessing on this one and I'd definitely ask whoever is doing your cam for you on what they feel would run best with their grind (whatever it may be). You'll also want to take heed of whoever does your converter in what they say for obvious reasons and see if both the cam builder and the converter designer can come to a collective agreement. Converters aren't an exact science either, just like camshaft designs. That's why many of the higher end converters offer a free restall because sometimes things don't go according to plan and need a little adjustment.


My argument when we spoke on the phone about shelf cams are simple. It's the same as this anology: it's like you going to the shoe store and asking for a shoe that you can wear. OK, well.... there's size, width, weight, price, softness/firmness, durability, purpose. A shelf cam (in comparison) is one of those "shoes" that is a compromise everywhere across the board because it's easy to sell and not have issues across the board with various users of all different types. That's really what it comes down to. Doesn't mean they're bad, but doesn't mean they're necessarily great either. It may work awesome for you, or it may not run as fast as someone else you knew that had one of the same grinds. As far as custom cams go - all you're doing is math and changing how the math is applied to the combination at hand. You can have two different cam guru's design two different grinds and still run the exact same 1/4 mile times. So who is better? Maybe both, maybe neither. Depends on who you ask, and who's buying.. Knowledge is obviously critical, but having someone who truly understands what you're trying to do is most important... and that's not cam experience, that's simply relating to the customer and giving them what they paid for because you listened to them throughout the whole process instead of focusing on the money at the end of the tunnel.

You don't need a "race cam" to go fast, but there's no sense in buying a cam that was designed around another motor when you've got your own agenda unless you're simply copying someone else's build (and even then - there's no guarantees of the same results). That's a waste of money. A well designed cam will give you the maximum amount of EFFICIENCY for the given specifications; optimization is what it's all about.

My point through all of this: you're overthinking this and it's causing you to go back and forth because there are a lot of unknowns that are impossible to know without physically trying it. Go with who you feel most comfortable working with and pull the trigger.. otherwise you're just going to get more confused because (you guessed it!) there's a LOT of opinions in this hobby. There are lots of very good people in the car world that know what they're doing with their own unique tricks and tips. The question really comes down to how you want to throw down more than anything.

 

Thanks for the link . . .