XJGPN

Okay, don't give me hell because its a totally different engine, but in Muscle Mustangs & Fast Fords they are doing a turbo engine buildup that will apparently be a test bed for a lot of turbo theories... This month's issue (March 2003) does a comparison test of 3 different cams on the turbo'd engine. The first was a stock cam, the second was a 216/224/112, the third was a 216/216/114. Basically, both aftermarket cams gave big increases over the stock cam, and the 216/224 and 216/216 had very similiar numbers up top with the 216/224 having a stronger bottom end. Once again, not an LS1.. but this is the first hard data I've ever seen comparing cam swaps on a turbo'd V8. It was interesting to note that the aftermarket cams did make such a significant improvement over the stock cam... That goes against one of the common theories. The other thing was how the engine favored the exhaust biased cam. How much of an effect do you think the LS1's excellent exhaust port affects how these cams would work on our cars?

<small>[ January 31, 2003, 01:22 AM: Message edited by: XJGPN ]</small>

smokinHawk

iTrader: (48)

I would have liked to see them also compare a reverse split cam on that turbo, to see if what i heard was true.

What about boost response was it didferent for the cams?

I plan to switch out my 224/224-114 cam with a 226/220-114 this year or next. I plan do get dynos to compare them to make sure i made the right choice.

SS00Blue

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by XJGPN:
<strong>How much of an effect do you think the LS1's excellent exhaust port affects how these cams would work on our cars? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I think that's why the crutched exhaust is of little consequence on the LS1. SBF exhaust ports are poor at best, even the aftermarket heads are backseat to the stock LS1 head.

SC-

MIGHTYMOUSE

iTrader: (59)

factory 5.0 heads are gross on the flowbench if thats what they use, flow somewhere around HALF what an ls1 head flows.

ive always thought (as the first cam shows, and the cam in my car) that for a streetable turbo car, you want to favor the exhaust side because that is the restriction on turbo cars.

turbolx

Unfortunately, I was a little disappointed in that article. What they tried were mostly blower cams that happen to make more power than a stock (.440" lift) 5.0L cam on a turbocharged stroker. It doesn't take a mental giant to pick a cam that makes more power than a stocker in this application. As Jon said, they missed the opportunity to try some actual turbo specific grinds that may have really surprised them. Hell, even a motorsport F-303 (that I run in my turbo 302) would seriously outperform the stocker, adding more cubes only helps the engine swallow that cam up. Something with larger lobes than an F-303 and either a healthy mirror pattern or intake favored split would have really made that article. Too bad they didn't do any homework first. I give that article a "C-" on a good day.

rodent

iTrader: (1)

I was thinking about getting this one from TR-

224/227 .563/.569 114

But I think it's meant to be used more with a supercharger/nitrous.

I'm trying to find something that will work with the LS1M kit, forged 6.0 bottom and a T-76 sized turbo.

XJGPN

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by turbolx:
<strong> Too bad they didn't do any homework first. I give that article a "C-" on a good day. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree 110%... they definately should have had several more cam choices... I would have loved to see them actually refine the search by using a number of cams that show the breaking point. I once saw an article on lobe seperation where they tested like 8 different cams from like 105 to 115 LSA on a small block chevy and you could definately see what the effects were when you went too far. While This article was lacking, I'm happy that there was at least one written...

redz_02

iTrader: (4)

i have always heard with turbos to use a smaller duration for your exhaust to increase exhaust velocity. Guess it depends on the car.

ChevyNo1

I'm sure all of us have heard that turbo's like reverse split, like a 220/216 for example . . . Greg, what do you think of that? I'm STILL running stock cam in my Incon TT car, I wonder how much I'd pick up by going to a cam like what I mention above . . .

- Dug

Rpm2800

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong>
ive always thought (as the first cam shows, and the cam in my car) that for a streetable turbo car, you want to favor the exhaust side because that is the restriction on turbo cars. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I would love to see more test like this also, and even on different engine types. Seems like the jury is still out on turbo grinds though.

But like the post above you says, the Ls1 heads, and mustang head flow characteristics are so different, and the Ls1 exhaust port is so good. (And mustang port is said to be very poor). That you can't really make a good comparison or draw a conclusion as to whether or not the bigger exhaust is better for a turbo car from this test. With the ls1 exhaust flow, it may call for a completly different type of cam.

While the mustang may have needed more help with the exhaust side.

XJGPN

I have definately heard the issues about the exhaust due to the fact that reversion is one of the bigger factors due to the elevated backpressure. The big question I have really comes down to LSA.... On this site I've heard about the reverse splits being good on turbo cars, but going to different sources you'll hear advice run the gamut from wide LSA (116-117 range) and favoring the exhaust to Tight LSA favoring the intake. Looking at turbo buicks I've seen a lot of people just running single duration cams with tight LSA. There are so many people's theories out there, but what I haven't seen is someone taking a turbo car and actually testing the different types and putting them on a dyno, to kinda cut through the theory bullshit and get a solid answer as to how these cams really affect the powerband on turbo cars. I kinda want to hear more from mustang people on this since they have a lot more turbo-8 experience than we do...

turbolx

FWIW, my general preference in turbo cams isn't all that exotic. We've had great success with stock cams in LOTS of these cars. Many people would be surprised to see just how far you can go with a stock cam and turbo(s). Witness Harlan's car making 573rwhp over a year ago with a stock long block. Good flowing heads go a long way toward helping a turbo car make power, even with a "small" cam. The stock LS1 heads flow really well, comparable with many aftermarket or ported 5.0L heads.

I chose the F-303 (226'/226' .512"/.512" 114') for my 302 specifically to kill some of the low end and move the power up in the RPM range so that I could get traction on the street easier and make more power once I'm hooked up. With my old stock cam, the power was literally a light switch adding about 180hp as soon as the turbos hit at 2500rpm. The new cam makes it easier to drive and just so happens to add about 40hp up top.

Once you've decided that a cam change is actually going to benefit you, there are a few things to keep in mind with a turbo. Most people know that overlap can bleed off boost at lower speeds, but you also need to keep exhaust energy high enough to efficiently drive the turbine. Excessively long exhaust durations can cut down exhaust velocity, especially on smaller displacements.

Your mileage may vary...

SS00Blue

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by turbolx:
<strong>Your mileage may vary... </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif"><img border="0" alt="[jester]" title="" src="graemlins/gr_jest.gif" />