SStolen

iTrader: (22)

Question 1: When Speed Inc or Lingenfelter make a 'turbo cam', do they use a specific lobe profile? I see some cams say 'aggressive profile' for all-motor cars and was wondering how that effected turbo cars.

Question 2: From what I have seen turbo cams usually have a traditional (i.e. 225/225) or narrow split (i.e. 224/226) duration where blower cams tend to have a wider split duration (i.e. 220/230). Why?

I have been looking for a cam for two weeks now and can't find one to save my life. I was spec'd out a 230/234 .590/.592 114+4 cam from Comp Cams but I don't have $400 for a new cam. I found a TR 224/224 .563?/.563? 112 for $200 and was just going to do it (the motor is ready to go together. The cam is all I'm waiting on.) The lower lsa should just raise the powerband a little higher in the rpms right? Speed Inc. recommended their shop turbo cam which is a 225/225 .58x/.58x 113lsa cam so we're only talking 1 lower number in the lsa. How bad could it hurt?

Question 3: How will the TR 224 cam profile and lower LSA effect the cars driveability and power?

Question 4: No one seems to have any proof that cams make that much of a difference on turbo cars so it couldn't be any worse than the stock cam right? 202/210 .496/.496 116lsa. I'm honestly just looking for a little lope in my exhaust note. Goal is 700rwhp with motor below. According to ForcedInductions.com, overlap woule be 'zero' (224+224=448/4=112-112=0x2=0) and turbo cams should be between -2 and +6 overlap. Or maybe it was -6 to +2 overlap. Either way I'm good. So should I do it?

engineermike

Aggressive lobes can benefit a turbo car just like it does NA. You still have to get as much air as possible around the valve and into the cylinder.

People will spout theories all day long about why more exhaust duration or why more intake duration. The fact of the matter is that very few people actually know from testing which one is better, and the ones that do aren't sharing. The other thing is that backpressure/boost ratio should play a big part in this decision, but none of the big cam makers ever ask for that info when spec'ing out a cam. The trend went from conventional split (e.g. 220/230) to reverse split (e.g. 230/224) and is now heading back in the other direction again. My personal cam is 224/236-114 and it works very well with the turbo. Don't worry so much about 112 versus 114. Either will be fine, though the 112 will move the power down in the rpm range just a tad. Again, no one has proven to me that narrow LSA is actually detrimental to turbo engine performance. In fact, the data I have shows the opposite to be true.

Slightly choppier idle, same or slightly more torque.

There is some testing out there that shows that larger cams do make more power on turbo cars.

Mike

Pro Stock John

iTrader: (34)

You are doing all that work to your car, only to skimp on how much you are going to spend on a camshaft?

And for example Speed Inc. has dynoed a lot of LS1 setups, so their cam suggestions are based on what they think works.

stevieturbo

ok, you say you havent got $400 for a new cam.

Then just use a stock LS6 cam. A couple of extra psi of boost is free, and I have no doubt a stock cam will easily have the ability to meet your power requirements on a turbo install..

SStolen

iTrader: (22)

engineerMike: The lower LSA moves the power down in the rpms?? When Comp Cams suggested the LSA, he said the higher LSA would move the power down. Regardless, you say that you have data that a higher LSA is not neccessarily better for forced induction?

PSJ: I am not skimping on the cam. Fact is, there is very little evidence available to the turbo community on what kind of cam works better for turbo'd cars. Like engineermike said, some debate more intake duration and some debate more exhaust duration. And it is usually whatever the trend is.

And its impossible to 'skimp' on a cam anyway. You make it sound like I'm using cheap rods that only support 800hp when I really need rods for 1500hp. You don't sacrafice quality by buying a used cam for less money and last time I checked, all cams were in the same price range. The TR224 has almost the exact same duration, lift and LSA as the SpeedInc turbo cam who knows their stuff when it comes to LSX motors and turbo cars. So let me ask you, are you so rich, and does it matter so much that you can justify spending $420+ for a 225/225 .583/.583 113lsa cam when you can get a 224/224 .581/.581 112lsa for less than half price?

stevieturbo

fact is....there are probably a hundred profiles, from mild to wild, that will allow you to meet your power goals.

Therein lies the problem.

Without proper dyno testing, nobody is going to be able to say what is optimun for your setup, or how you want it to drive or deliver power.

So if you want a big lopey cam, fit one. If you want a nice smooth cam, stick with stock, or a smallish cam.

Or just go for something in the middle.

IMO any of them will be able to make 600+rwhp on a turbo setup anyway.

Didnt MM make some silly numbers 7/800rwhp+ on a stock F-body cam ?

And Im sure countless other guys have had excellent results, with similarly tame cams.


if you were pushing for every last ounce of power from an engine, then cam choice might become extremely important. But when most FI LS1's are pretty mildly tuned ( they make power, but in terms of power per ci, they arent pushing things ), the cam really isnt that important.

engineermike

Tighter LSA moves the intake lobe earlier in the cycle. Earlier intake lobe means earlier IVC, which is the most influential aspect to RPM on the cam. I could list a ton of examples, but here are a few:

Car Craft did a dyno test on a 355 SBC with 3 different LSA's: 106, 108, and 110. The tighter LSA's made more peak torque and the same peak hp at the same rpm, but signed off quicker after peak.

TR CheaTR cam is only 214 in the intake, but peaks past 6000 rpm. It's on a 117 LSA.

The LS7 is a big 427 that makes power to 7000 rpm on a little 210 intake lobe that's on a 120 LSA.

The Buick 3.8 turbo stock cam is on a 106 LSA (there goes the whole "wide LSA is better for turbo's" theory) and it peaks well before 5000 rpm.

I could go on. . .

95ZRagtop6M

Good, because the cam I have for my new turbo LT1 is on 110LSA.
Just ordered my OFI kit.

stevieturbo

its not as simple as that.

a 200/200 on 110LSA is not going to behave the same as a 250/250 on 110LSA

SStolen

iTrader: (22)

Stevieturbo: I've already made the numbers in my sig with my STOCk 2000 LS1 cam. Power is not what I am worried about. (I would like to make more power on motor to not have to run as much boost but it's not my priority.) Like I mentioned before, I just want a little lope. But at the same time, It would be nice to have a cam that would tie it all together. It's just not going to happen. Too many possibilities and not enough information being shared to make a sound decision on exactly whats best.

Pro Stock John

iTrader: (34)

Sure go for it, should peak lower and have good power under the curve. Not sure where it will peak, but it won't peak the as as it was 114.

I'm running a 236/236//113 or so, Speed Inc. Spec'd it.

If you know Intmd8 at Speed Inc., Jim has downsized in camshaft to improve the street manners of his combo, like the idle quality. He's admitted here and there that a given combo made less power with less camshaft. I think he ended up with a 218/218/112 in in his LT1, but had run as high as 230/230//114 I think.

SStolen

iTrader: (22)

Yea, thats why I'm thinking the TR224 will be nice. Should increase power a little, have a nice lope and after I drill out the TB with a 13/64 bit it should idle nice and smooth.

Pro Stock John

iTrader: (34)

Will make more power than a stock cam. You should dyno before and after, and help advance our knowledge of how much power can be gained from the swap.

black98ws6ta

iTrader: (77)

He obviously is too broke for that

black98ws6ta

iTrader: (77)

Or you could use the set screw to get your IAC counts to where they need to be so you dont ruin the possibility of that tb ever working with a smaller cam again.

stevieturbo

I think that is all it boils down to.

Searching this forum will yield results of what others have used, and how they have worked for them.

But when there are just so many variables, only dyno testing will reveal what is best for your exact combo.

My own reccomendation is dont get fooled into thinking bigger is better. Of course everyone has different ideas about that, but I would stick with a mild cam, under 230 deg or so.
Perhaps more so given you are a M6 car, so low end manners might be of more importance than if it were an auto.

As for drilling the TB...its quite easy to solder back up again or plug it up somehow if need be. Just dont drill the holes too big.

95ZRagtop6M

That is correct.

Pro Stock John

iTrader: (34)

We need to create 5 questions that folks always answer before we start talking about cams or turbo sizes:
-Power Goal?
-Street? Strip?
-ET/MPH goals
-Vehicle weight
-Streetability important?

topend

your leaving out duration. When u look at cam u need to look at all of the specs. LSA is just part of the picture. To figure overlap u need to know the duration and LSA. I think u could get away with more overlap with a supercharged motor than a turbocharged (unless u have a intake/exhaust pressure ratio closer to 1:1).

engineermike

. . . preaching to the choir.