This cam good for turbo?

[aleborjas]

The higher than LSA, the better the cam is going to work with forced induction. It determines how peaky or flat your torque curve is going to be. I believe the stock cams have an LSA of 115.5, stg 1 NSR is 114 and stg 2 is 117.

higher LSA = wider curve
lower LSA = narrower curve

Think of duration as a seesaw, it teedles and toddles your torque one direction or the other, depending on how high the duration is or how low it is.

how do you know that a forced induction engine with higher LSA will have a wider torque curve? nice to know that!

 

[jroc07gt]

how do you know that a forced induction engine with higher LSA will have a wider torque curve? nice to know that!

A while back I spent quite a bit of time researching cam specs, ran into a section on comp cams website that showed what made they blower grinds different from their n/a grinds. The lift should be enough that it flows 20-25% more than your actually flowing, overlap also plays a pretty big role in blower cams, etc. There is plenty of websites that offer loads of free information on the subject, if you're willing to read. Even with all the information in the world though, it's still a guess without all the data and testing to back it. That's why it's best to go with what BBR recommends, imo their stage 2 is the best.

 

[*JZ*]

I saw that springs were recommended, anybody had any problems with that much lift on stock springs w/Stg 1?

The Stage 1 cams don't come anywhere near the lift that will deem the need for a valve spring upgrade. It's a recommendation, but not a requirement.

where i can read the article of BBR?

Last months issue of Muscle Mustangs & Fast Fords.

 

[Buddyweiser]

Generally a cam with a higher lobe separation angle(LSA) and a long exhaust duration will work with a F/I engine.

 

[beefcake]

The Stage 1 cams don't come anywhere near the lift that will deem the need for a valve spring upgrade. It's a recommendation, but not a requirement.



Last months issue of Muscle Mustangs & Fast Fords.

Saw the article, very good read

 

[jroc07gt]

Generally a cam with a higher lobe separation angle(LSA) and a long exhaust duration will work with a F/I engine.

Found a thread backing up this information.

http://www.supraforums.com/forum/showthread.php?t=404377

It's for the supra, but still useful information.

 

[aleborjas]

A while back I spent quite a bit of time researching cam specs, ran into a section on comp cams website that showed what made they blower grinds different from their n/a grinds. The lift should be enough that it flows 20-25% more than your actually flowing, overlap also plays a pretty big role in blower cams, etc. There is plenty of websites that offer loads of free information on the subject, if you're willing to read. Even with all the information in the world though, it's still a guess without all the data and testing to back it. That's why it's best to go with what BBR recommends, imo their stage 2 is the best.

sorry but can you get me the comp cams link?

 

[jroc07gt]

sorry but can you get me the comp cams link?

http://compcams.com/Technical/FAQ/CamandValveQuestions.asp

Turbo cams in fact, should have less exhaust duration than a N/A cam.

Superchargers also increase cylinder heat and tend to work more efficiently with a wider lobe separation.

Typically, camshafts intended for use with power adders will feature a wider LSA and more exhaust duration than those intended for use in a non-boosted application.

Note that a tighter lobe separation (smaller LSA number) results in a narrower and peakier torque curve, and a wider lobe separation (larger LSA number) produces a broader torque curve.

Just read all of that, you'll learn a lot.

 

[US-1]

 

[Bobby]

i put in the bbr stage 2 and picked up 70rwhp with 2 less pounds of boost. the car made 707 @ 16psi on 93 octane. through the stock heads.

 

[ALLOY GT]

i was just curious i have a 5.0 8.8:1 stroker stage 3 ported MMR heads +1mm oversized valves bbr stg1 cams and building my turbo kit its a t-76

 

[Buddyweiser]

I'm unsure about what you're laughing about.

 

[turbotr]

If you're running alot of boosted power, generally the exh side is having trouble getting the exh out. That's not hard to imagine. Seems it should open earlier is what it should do, not have "less duration" in general. That seems like an odd generalization, to me at least.

It does make sense to minimize the overlap too and not hang the exh side open past TDC. Overlap in the turbo case just sprays exh into the intake (and reduces fresh air intake), since the exh pressure at full boost is generally much higher than the intake pressure. You can actually see the evidence of this via all the exh soot in the intake ports and manifold.

This is not from a mod motor, but similar physics apply. Here's a WOT cylinder pressure trace out of my own boosted turbo engine (a turbo v6) at about 26 psi boost (I have the pressure measurement gear). This was taken years ago, back in about '99 or so, and the engine was just about 700 hp'ish back then. It shows that in this case, the exh "blowdown" is not even finishing until the exh stroke is halfway completed (lol).

Edit: Work won't allow connection to Photobucket; I'll post the pic later.

As promised. The square wave signal at the bottom is the crank position signal, for position reference. In this case it's 1 pulse per cylinder, 120 deg apart (even fire v6). Rising edge occurs at 10 deg BTDC. 50% duty cycle.

Kinda new to the Mustang world, but of course plan to do pressure traces for the boosted mod motor as well. Have an '06 GT with a Whipple HO kit now. Should be interesting.

TurboTR

PS- I appreciate the effort and all behind that Supra cam comparison. However, they show only a 6 hp difference between the 3 scenarios. That's less than 0.5% difference. To me, that sort of tiny delta kinda falls within the noise band of even just run-run variance. Could the dyno runs repeat within less than 0.5%, even with no engine changes? That might be quite an engineering challenge. So taking note of the results, but not losing sleep over it either.

 

[circusboy]

I just scored a set of used Stage 2's. I'll let you know how they work for me lol

 

[2mchtoy]

I'm sure s.d is "testing" a couple of sets of cams for his ride. We will be reading in a bout a month of his new"turbo" grind cams. right s.d?

 

[US-1]

 

[Chris06GT]

They catch on quick S.D.....

 

[US-1]

From time to time........

 

[05mustang_TT_charged]

I just scored a set of used Stage 2's. I'll let you know how they work for me lol

Let me know how they work for you, hopefully this high boost twinscrew cam design I just got works out and maybe even pick up a few horsepower.

 

[circusboy]

Let me know how they work for you, hopefully this high boost twinscrew cam design I just got works out and maybe even pick up a few horsepower.

I'm not sure why your changing cams, but I will take these off your hands gladly lol. You can't get all your power to the ground now, lol, unless you made some changes i don't know abaout