JDMZ28

iTrader: (1)

The Comp Cams Extreme Energy 268 and 274. They spec at:

Duration @ .050: 224/230 230/236
Lift :.480/.487 .487/.490
Lobe Sep : 110 110

On paper there isn't much of a difference. But is there going to be much of a difference in a 350? The reason I ask is because CHP used the 268 in a 350 w/TPI heads and a setup similar to mine. With the 268 they made plenty of power and didn't loose any low end. I want to use the 274 but I want to make sure I don't loose any low end in the process. What do you guys think? My car's specs are below.


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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframes connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> Homemade ram air, B&M shifter, Extreme Energy 230/236 cam.

The ODB

that's a pretty big difference actually. With more duration and the same 110 lobe sep, the overlap will be much more.

they are both too big for a street driven 350. It will run, but be low on power and more difficult to tune.

ODB

JakeJr

I agree, unless you're running well over 10.5:1 compression and need to bleed off some cylinder pressure.

You're in the right family though. The Xtreme Energy series are outstanding profiles.

I just think you went one step too high in your selection. 218/224 would be about as high as I'd go without having or planning a lot of other mods to improve the high rpm breathing of the engine.

Aftermarket heads, like Air Flow Research 190 or 210s, would be needed to take advantage of the flow potential of longer duration profiles.

Over all, you'll be a lot happier with a shorter duration cam. You won't kill the low end, idle will be a lot better, vacuum will remain high so the brakes will continue to work without a hitch and gas mileage will be better.

What you really need to do is sit down and give CAREFUL consideration as to how the car will be used for the majority of the time. List on a sheet of paper the characteristics in the order of their importance to you. Choose your profile the meets your most important expectations.

Guys generally over-cam their engines; it's been that way for as far back as I can remember. Somehow the thinking that "bigger is better", but it ain't so with camshaft selection.

I'll bet if you call CompCams on their toll-free Tech Line, they'll recommend a shorter duration profile too.

Just trying to help.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited February 24, 2001).]

87RS402

I'm in the same boat, so to speak. I have just been commissioned to do a 350 for my friends camaro. He's thinking about the XE274. I think it will work but not a real good choice for a daily driver. His might see 2500 miles per year. It will be carbed, and running stock heads, ported of course. I think the 1.6 rockers are out unless you want to modify the heads for the lift. I'd be interested in hearing everybodys thoughts on this cam in a 350 too.

Vader

JDM,

I definitely lost some low-end power with an even lesser cam - .510"/.510" - 220°/230° - 114° LSA. This is a 350 with 10.6:1 static, ported stock heads, 2.02:/1.94" valves, ported plenum, yada, yada. Once the revs pass 2,500-2,800, it doesn't matter. The torque comes back to levels even better than before. Idle is a bit lopey (barely detectable) and launches are a little slower. I do need to get a different converter to make the most of the cam. I actually make more HP with a carbed 355 and .473"/.473" - 222°/222°/ - 114° LSA. This engine supposedly has "worse" factory heads (ported, of course) and a cast (nodular) crank. It does run at 11:1, though.

Like Jake said, more is not necessarily better in cam profile numbers. (Pay attention to this guy - he seems to know his sheot.)

------------------
Later,
Vader
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"No matter how hard you try you can't stop us now..."
Adobe Acrobat Reader 4.0

JDMZ28

iTrader: (1)

would I be better off going with the 268? CHP did a test with this one and it made great torque.

Keep in mind I have a 5 speed with a 3.35 1st gear and a 3.73 rear gear. It goes through the gears really fast.

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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframe connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> B&M shifter, Extreme Energy 230/236 cam, Holley street dom intake.

JakeJr

Selecting a performance cam is actually an exercise in trade-offs - To get one thing you have to give up another, to a degree.

To get excellent high rpm power, you give up low rpm torque, idle quality and gas mileage and over-all driveability. When you shoot for low rpm torque, etc., you give up high rpm power. The trick is to try to get as close as you can to the best of both worlds.

The thing that most of the mag dyno reports don't show you is off idle/low rpm torque. Almost all of the dyno reports you see begin at 2500 rpms or higher. I believe this is because most dynos can't log power levels below that.

Since most of your street driving will probably be below that rpm level, it becomes very important how the engine performs at those lower rpm levels.

Don't get sucked in by peak numbers; look at the average numbers to get a better handle on how the engine will perform in a street environment. You'd want a broad power band as opposed to one giving slightly higher power but is "peaky".

Advertisers thrive on selling peak numbers and most often ignore and don't comment on the 'down-side'. Many claims are exaggerated too.

If you went through one of the mags and picked out and bought all the mods that are advertised and actually got all the power they claim, you'd be making as much power as a Pro Stocker.

With a broad power band you end up with better over-all power across the rpm band but you give up a bit of max power. With a peaky power band, you see slightly higher peak numbers, but the engine must be maintained within that narrower rpm band for that cam to be effective.

Sometimes the mag articles will give you some subjective info on how the engine idles and its part throttle response, but not usually. You've got to decide how important these two features are to you.

With a lot of tuning you can get a "bigger" cam to perform well on the street. This will primarily involve carb tuning, timing curve and dealing with reversion.

Some guys don't mind revving it up and dumping the clutch to get decent off idle acceleration. A daily driver caught in rush hour traffic is one thing; a Saturday Night racer is another.

I get the sense that you are definitely leaning toward the bigger cam. Well at least you can take comfort in the knowledge that it can be swapped out if you find you can't live with it.

Remember, too, that in order for a longer duration cam to pay dividends, your entire intake/exhaust system has to be able to flow enough to take advantage of the add'l flow the cam can give. If your heads can't flow exceedingly well, a longer duration cam is a waste. The heads become the bottleneck to add'l power.

Try to keep the whole picture in mind as you select a cam.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited February 26, 2001).]

JDMZ28

iTrader: (1)

Thanks to all who replied. (I don't know how to say this without being ****y or a know it all but here it goes) Believe me guys I have done countless hours of research on the whole cam thing and I've hit it at all the angles I can think of, I guess what I was looking for is someone who has actually put one of these in their car. This is not unheard of. Someone out their has a car with cast iron tpi heads with a large cam.

As far as driveability, that is important to me, I want a choppy idle but not dragster choppy. I just don't want to have to burn my clutch out just driving the thing around town. The car has globs of low end right now, I would like to trade a little for power. What ever cam will give me about 40hp and a 5500rpm hp peak that is just fine(I have a stock roller corvette cam), I also don't want it to be undercammed. I would hate to go through all the trouble just to find no power increase.



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1986 CAMARO Z28 -> 151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframe connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> B&M shifter, Extreme Energy 230/236 cam, Holley street dom intake.

The ODB

well after all those countless hours of research, just put one of those cams in and finally learn for yourself what it does.

You can always change back if neccessary.

Blown GTA

I apologize JDMZ28 but this is directed to Vader. I would have normally asked this via e-mail but can't find an e-mail address for Vader. I also find myself in the exact predicament in cam selection.

Vader: I have a 383 shortblock thats in the works, and its time for selecting a cam. How would you rate your cam 220/230 .510 114 from your experience in a 383 as far as tradeoffs? What would I be giving up? What would I be gaining? What would maximize the effectiveness of this cam in a possible daily driver/weekend cruiser?

Heres how this engine is going to be assembled.
Fully ported Edelbrock lower manifold
Fully ported Superam upper intake
52mm Ported GM Throttle body by AS&M
AFR 190 assembled per Performance Heads in AZ
Hooker LT headers to Mufflex y to 4" catback
Pro-Built 700R4 tranny with 10"converter@2200
3.50 Ford 9" Currie Built rear end.
MAF conversion to MAP via DFI ECM and custom harness built per F.I.S.
Possibly Pro-Charger blower new Self-contained units (heads have been already purchased with 74cc with TRW forged flat-top slugs with 9.5:1 compression)
Custom tuning hopefully by self

3.1 firebird

if in doubt go with the smaller cam. TO big of a cam runs like crap, but a slightly small cam will run grear. Trust me, I have first hand experience on this

Ray87Z

I run the next smaller XE cam, the 218/224 cam. I've been really happy w/ it. I have an auto w/ a 2200-2400 rpm converter from Darrel Young ($199 I believe it was) and 3.42 gears out back it seems to do just fine on torque and drive-ability. Slight lope at idle to me, no rowdy idle or anything though (sounds mean at 650-700 rpm idle to me).

In one of the CHP articles where they used the 268 they stated the 262 would probably yield similar HP numbers but w/ better off idle and really low end torque. Just conjecture as they didn't dyno test that though.

------------------
Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

Box of Rocks

JDM,

I'm currently running the XE274 in a 327, 4-speed car. It is wonderful, pulling well from 1,700-1,800 to 6,700-6,800 RPM.

My buddy has the XE268 in a 'matic car, with a 2200 stall. It too is wonderful. Off-idle to 6,000 RPM.

You WILL do best with the 274, but only because you have a stick car. If it were a 'matic, I'd recommend the 268.

In a stick car, you will not notice the difference in drivability (bottom-end torque) because you will rev the motor to 1,400 RPM from a dead stop as a matter of course - it's a stick car - you would do this with a dead stock L-98.

The 274 is the preferred cam for the 350 engine with stickshift when headers, intake
and carb are used.

Know this: those stock heads will be your restriction. If you can take the time to carefully port, polish, and gasket match the heads and smooth the intake imperfections, you will see 80HP over stock with the 274.

And, one last thing: what Vader said is true I'm sure, but I'll wager a cup of Columbian with cream and sugar that he was not talking about the Comp Cams Extreme Energy line of bumpsticks.

Comp let the rest of the industry in the dust when they released this line in 1997. The XE cams use a much faster-opening intake ramp that is timed to begin opening later in the cycle than other cams of similiar specs.

Bottom line? The 274 has plenty of vacuum at idle to operate power brakes, pulls from 1,600 - 6,400 in a 350, and has the perfect "street bad-boy" idle.

Remember, I'm running a SBC with stickshift. My racing buddy has the other combo - 268 with matic in a 2nd gen Camaro.

WE KNOW FROM PERSONAL BTDT - not speculation.

Good luck.
BOR

Box of Rocks

Vader,
The duration at .050 is 220/230 but what is seat-to-seat duration? This, along with the 114* LSA is the key to sluggish bottom-end.

Granted, you cannot run a Comp XE cam with super-fast opening ramps and a 110* LSA on a computer-controlled vehicle, but our subject here is not a smog-legal car, it has a 650 CFM double pumper with intake and headers.

So his cam choices fall into a different realm of opportunity. The closer LSA improves midrange torque, and the faster ramps help bottom end and vacuum.

The 274 has 230* duration at .050.

That means 44* rotation from .050 to max lift.

I'll guess that your 220/230 is rated at 282/292 at max lift if it's a Crane cam, with the usual 62* rotation from .050 to max lift.

The difference between the ramp (44* vs. 62*)
and the difference in LSA (114* vs. 110*) make these two cams WORLDS apart, even though lift and .050 duration look close.

Of course, you're still the supreme inter-galactic mondo engineer/builder/sage/seer and personal hero to me.......BUT.....

Ain't no substitute for running the EXACT same two cams the writer is discussing.

Oh, lucky me.....with the mouth......


BOR

burnoutrpm

i went with the 262 mainly because I HAVE TRIED WHAT YOUR THINKING!!!! man,. dont do it just get like the 262 or 268 those and the ones you can use with no effect on bottom end! trust me you dont want to give up your low-end grunt i mean thats what makes the seat of the pants feel when you floor it. you wanted someone who has that sort of cam now!! well..... i do and am putting in a xe262 next week it goes from 1300-5600 perfect great bottm-end and revs to about 5800 STILL making power!!!! get this one you'll likes!!!!!

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1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 160 (882) heads,.447/.447 lift 222@.050 duration speed pro 327/350hp cam 350 .40 over (356) edlebrock performer rpm intake and a 600 edlebrock manual choke (1405) Proform H.O. distributor slightly revised 700r-4

Future mods comp extreme energy roller cam, world products sportsman 2 heads, msd 6al ignition, billet distributor, blaster 2 coil and a 406 engine is in the works soon!!!!

84TransAm

I'm in the process of researching camshafts. How well would the XE 262 work on an LG4? By then i'll have Headers, and a new intake (probably performer, hopefully RPM) Heard it is good for 40 hp on an LG4, but don't know any characteristics of it.

------------------
--Steve S--
1984 Trans Am 305 LG4, 5 speed
Daily Driver, Flowmaster 80 Series
NOW FEATURING: Holley 600 cfm & vacuum advance

FastBroker

XE262 and XE268 are fine for daily drivers, with 262 being best for low-end. Can make 350cid with 350hp pretty easily with that cam and 1.6 rockers, good heads and exhaust, 9.0:1 CR.

JDMZ28

iTrader: (1)

BURNOUTRPM:

Did you use the XE274 specifically? When did the power start to kick in? What gear do you have? You DO run an automatic, and I know how they die when they shift into second, this is when the lowend becomes crutial. How much lowend did you lose?
I believe every word you are saying but, you must remember how my car is geared. To give you an idea. Here are my shift points in each gear reving to 5000rpm. 1st 30mph, 2nd 50, 3rd 75, and 4th 100. My car needs hp. It has almost too much torque, I would gladly trade off my low end for some top end. The car is never below 3500rpm on a full throttle run.

BOX OF ROCKS:

What kind of heads/compression are you running on the 327? Where does your horsepower/torque peak? Like I said in the paragraph above the car never runs below 3500rpm on a full throttle run, with the 274 cam I would shift at 6000rpm then it wouldn't go below 4000rpm. I'm sure I could lose some low end cause 1st gear is the only time I use it and as of now my car goes through 1st like an animal.

The thing of major concern is LOSING TONS OF TORQUE AND GAINING LITTLE HORSEPOWER. That would scare me if I was running, say a performer RPM cam, this cam would cause me to rev to 7000rpm and run 244* duration. But that is not the case. Power will most likely be peaking around 5700rpm (under 6 grand), the cam features less than 500 lift and I have a free intake/exhaust. Yes my heads are the bottle neck but the XE274 is not that large a cam. BTW. How IS your cam on low end? You do have a smaller engine than me though. I am seriously contemplating the XE268. BTW. comp cams actually recommends this cam for my specific engine.



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1986 CAMARO Z28 ->
151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframe connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> B&M shifter, Extreme Energy 230/236 cam, Holley street dom intake.

1987 TRANS AM ->
73,000 miles, 305TPI, auto, all stock.

JakeJr

I came across some add'l info on the two cams you are considering, maybe this will help you in your choice.

The 268 has a torque peak at 4000 RPMs and a HP peak at 6000.

The 274 had a torque peak at 5000 and a HP peak at 6300.

This was in a 350 with a manifold/carb Chevy SB engine.

The dyno results began at 3500, but how those cams work down low wasn't listed. There were no comments on idle quality, vacuum or tip in response. The article was dealing with how a stock set of valve springs effects power up top.

Generally, you can run a cam that's one step up (duration-wise) with a stick than with a auto trans, unless you've got a high stall converter. With an auto trans, as someone else mentioned, it's the one-two shift that's the killer, pulling the R's down and taking the engine out of the meat of its power band. With a stick the ratios are tighter so the negative effect is less.

Usually shifts are made at around 10% beyond the engine's power peak, so the 274 would be shifted at about 7000 and the 268 at 6500 or so. This keeps the engine in the meat of it's power range and gives the best ETs. Of course, these points can be fudged depending on intake/exhaust flow restrictions, etc. Back to back runs using different shift points will show which rpm is best for your combination. Use MPH as the barometer, not ET.

I use to drive a '23 "T" roadster 1/4 mile drag car with a 482 BB that ran mid 8's and I tried shift points as high as 8200 all the way down to 7000. ET and MPH remained basically the same at the lower shift point, so I kept shifting there (Turbo 400/5500 stall) instead of stressing the engine unnecessarily by buzzing it higher.

Your mileage may differ.

Remember, too, that the 1.6s will add about 2/3 degrees more duration to the cam specs and somewhere in the area of .030 more valve lift to the advertised numbers.

The Xtreme Energy series of cams from CompCams already have very aggressive ramps and adding 1.6s make the valve action even more so. Springs become even more critical with that combo and CompCams highly recommends that all the other valve train components be upgraded when an XE is installed.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

Box of Rocks

JDM,

I'm using the old G-1 TFS heads that have been seriously ported, polished, port-matched, and chamber work. I've never flow benched them, but I'd guess conservatively that the 190cc (now) intake ports flow 265 cfm at .500 lift, with exhaust coming in at about 210 cfm.

That is conjecture, but it's based on real-world tests of other, almost identical heads I've seen figures on.

Burnout:
I couldn't help but notice your sig shows you're using a Corvette L-79 repop cam circa 1966. Funny, I threw my L-79 cam as far away as I could from my 327 motor in favor of the 274 XE Comp unit. Your car has weak bottom end because that cam ain't too red-hot, sport.

1966 cam profiles utilize 1966 technology, even when they're ground in 2001.

Anyway, as I said at the beginning JDM, the 327 pulls well from about 1,700 - 6,800 RPM in the 327.


Jake:

You have helped steer this where it needs to be. My combo may differ from others, since I'm using a port-matched Torker (the old, straight-runner design, not the new shi++y torquer 2). Most guys use an Edelbrock Performer RPM - but those don't fit under a stock 1966 Corvette hood.

Also, instead of 1-5/8 primary tube headers, I'm using 1-3/4" Super Comps from Hooker.

You can readily see I was building a 7,000 RPM motor - and that's exactly what it is.

NOW : I responded to this thread ONLY to explain my very real surprise at how well the XE274 pulls from low-RPM, even in a 327.

I think our writer here is already convinced he knows what to use.

You've built and piloted some fast stuff, Jake, and I'll bet you a cup of French roast you've been surprised by the low-end grunt of some of the new "fast ramp" designs too, huh ?

They almost act like little mini-rollers the damned ramps are so quick - and that makes torque & power. I'll best they're spring busters at 7,500 RPM on hydraulic cams.

Nice to hear Comp now has a full line of solid-lifter XE cams. Nya-ah-ah.


BOR


[This message has been edited by Box of Rocks (edited February 28, 2001).]

jcb999

fyi

http://web.camaross.com/bb/Forum13/HTML/003403.html

I have also seen a 274 combination produce similar peaks rpm numbers for torque and Hp.

You will probably need something other than a stock head to take advantage of the 274.

If you have 3.7 or better gears the 274 cam should be fine. Comp says 222 degrees at 050 for stock gears (3.42 or higher) is about the limit. And I think that is a pretty accurate rule of thumb. You can always work on improving low end if you are in the ball park. A change of 10 to 12 degrees at 050" will only move the power band around by about 500 rpm and that is easily compensated for with a little timing curve and the like.

[This message has been edited by jcb999 (edited February 28, 2001).]

JDMZ28

iTrader: (1)

BOX OF ROCKS:

I will be using a holley dominator intake 0-7200rpm, holley 650 dp, 1 5/8" headers, 9.5:1 compression.

Does this sound about right? My new redline will be about 6300rpm with hp peaking around 5700-6000rpm and torque in at about 4000-4500rpm. I would like to keep my redline under 6500rpm, do you think it will be that low. This cam should also net me a good 40hp, right?

------------------
1986 CAMARO Z28 ->
151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframe connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> B&M shifter, Extreme Energy 230/236 cam, Holley street dom intake.

1987 TRANS AM ->
73,000 miles, 305TPI, auto, all stock.

JakeJr

You're absolutely right, BOR, today's camshafts, especially the XE series, are night and day different from the the lazy cams of years gone by.

Based on JDMZ28's last post, the 268 would be the perfect cam. It has HP and torque peaks exactly where he's looking for them.

I agree, too, that the heads will be the bottleneck to max power. At some point that will have to be addressed.

I've got a ton of head flow numbers and it's amazing how some of them actually lose flow once, say .500 valve lift is exceeded.

It's an old drag rule that most races are won or lost in the first 60 feet. Playing catchup most often leads to breakouts in handicap racing. Blowing by the guy on the top end, only to break out in an exercise in frustration and futility.

So off the line performance has to always be maximized if you plan on winning many races. That's why guys pay so much attention to their 60 ft times.

It's good we're kicking this around. Maybe with all the feedback he'll end up with the 'right' cam on the first try.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

JDMZ28

iTrader: (1)

Your right jake jr. I am starting to lean more toward the 268. Although I think the peak numbers will be larger with the 274 cam the 268 will definitely not be too big. I will probably not get much more average hp with the 274 at the expense of low end power. Plus, I don't want to spin my engine over 6000rpm on a regular basis. So until I get my new heads and stroke it I think I'll be using the 268. Unless I talk to someone that has a 274 in a 350 with a similar setup to mine. Thanks for all your input guys.

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1986 CAMARO Z28 ->
151,000 original miles, 43,000 on 89' vette 350 block, Holley 650 DP, Weiand intake, 1.6 rockers, 1 5/8" headers, no cat, 2 1/2" Flowmaster catback, Mallory coil, March pulleys, T5 with 3.35 1st gear and 0 miles, 90% Centerforce clutch, 3.73 posi, Eibach 1" drop springs, Spohn LCA's, Spohn adjustable panhard rod, Subframe connectors, polyurethane swaybar bushings/endlinks, 2 12" Sound Streams, 2 Infinity 6X9's, 2 Pioneer 6X9's, 800 watt Lanzar Vibe amp. ET 13.22@ 106.4MPH 3300lbs less driver and speakers Next mods-> B&M shifter, Extreme Energy 230/236 cam, Holley street dom intake.

1987 TRANS AM ->
73,000 miles, 305TPI, auto, all stock.

83 MidniteZ

I am also debating between the XE274 and XE268. Which one would you guys recommend for with a high compression such as mine (11:1). I am running a manual transmission and have 3.73 gears. It is a daily driver though.

RB83L69

274

83 MidniteZ

Thanks RB

SMasterson

1.94 exhaust valves, that a typo, right? <grin>

Just kidding.

As to the thread, I'm using:

SLP 51006 advertised:
Int Lift .495
Exh Lift .502
Int Duration 218
Exh Duration 224
Valve events from SLP At .50
intake open 1- btdc
exhaust 50 bbdc
close intake 39 abdc
close exhause 6- atdc
3 advance degrees built in
114 Lobe center

The valve overlap, (or lack of it, -7.0) seems to be KILLING me on horsepower!

The cam I'm using is almost identical to a crane 119821 in DD2000.

Compare it to a compcams 12-412-8, and other Hyd\Roller cams.

Am I REALLY giving up 54 hp and 65fpt at about 5000 with the SLP cam compared to the Comp Cam listed above?!?

I will definately want to check the valve timing events on any cam I was choosing in the future!

383SBC, 11:1 SRP, TFS23d Heads, 730SD Tuned Port ECM, Ported plenum, Accel intake, SLP runners, BBK 52mm TB, Hooker long tube headers through 3" 40series Flowmasters all the way from headers to tailpipes.

G-Tech pro show a best of 325rwhp at 13.93 in a 4040lb '89 GMC pickup. (No traction for the first 60' or so)

cp87GTA

I agree completly with Box Of Rocks!! I'm running the xe268 in my tpi car. I don't know how much more torque anybody would want. I would use the 274 for a stick car. A good port job or after market heads will yeild the best results. I'm running 87 tpi heads ported pretty good, and it'll pull 6200 in a heartbeat. NOW I'm thinking I should have WENT BIGGER. Most guys that build a car like this isn't conserned with fuel econemy, although I get about 15-16 mpg intown. 274 ALL THE WAY!!

Mkos1980

iTrader: (8)

I went with the Xtreme 218/224 ,TF 195 Heads, Edelbrock base and ASM Runners and the car hauls 10x's better then the old L98 used too.