BuckeyeROC

Just wondering what you guys are running w/ the HOT cam. Please post times/MPH and setup. I have a friend considering it. Thanks.

------------------
89 IROC-SuperRammed 355 w/ AFR 190's and LPE 219/219 cam-http://www.geocities.com/buckeyeroc

Kevin91Z

iTrader: (1)

Not yet, but pretty damn close to it. My problem is traction.

------------------
1991 Camaro Z28
5.7L 5-Speed (originally 305)
318 RWHP, 419 RWTQ
13.23 @ 107.62 MPH (2.13 60')
Southern California
Member: SoCal F-Bodies
-=ICON Motorsports=-

RCR

Not really sure, but now I have the LT1 intake on it, too. Should be a good match.

Matt87GTA

Judging from some of the street races and a few other things, I would say I could get under a 13.0 with some sticky tires. I second the traction problems comment.

------------------
1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

kevinc

Me: 13.19sec @ 103mph

Mike Davis: 12.18sec @ 109.6mph

Both are running LT4-HOT cams, but with different heads (me: 'Vette heads, Mike: AFR) and a few other variations.

------------------
1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

GofasterFirebird

iTrader: (3)

That 102.39 (rounded to 103) doesn't say much for the hot cam. I went over 103 with a 206 212@ .050 cam. sure I have afr heads, but I also have a bunch that holds them (heads) back, so don't go blaming the heads! Maybe I should look into another cam.

------------------
1991 Firebird
350 L98 (was a 305 TBI),T-5,Edelbrock TES and cat back,Accel manifold
NOS,subframes,jegster torque arm,MSD Digital 6
AFPR,Lakewood lcas
Hurst linelock,SLP cam (206 212 .480 .486),relocated battery,cold air,Hypertech chip,centerforce df,clutch
poly bushings and mounts
AFR 190s
Harland sharp 1.5 rockers
autopower rollbar

12.33 @ 114.83 juiced uncorrected

13.510 @ 102 non juiced uncorrected

Matt87GTA

Judging the top end performance of the LT4 HC when it is being used in a LTR setup is pointless. The LTR setup will hold the top end charge back every time. If you want to know what the potential of the cam is, go look at some of the low 12 second fourthgen LT1 cars that run the LT4 HC N/A.

And I'm gonna go ahead and blame that poor-excuse-for-a-PROM Hypercrap chip on your setups 'problems'.

And regardless of what you are trying to say about the lack of importance the heads have on the end result, AFR heads will always out-perform vette heads and there is something to be said about your running them and how your car performs - even with a 'small' cam.

my $.02

------------------
1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

TPI Guy

My thoughts on the HOT cam:

Duration @ 0.050" Lift w/1.6: 218 / 228
Duration @ 0.050" Lift w/1.5: 216 / 226 (approx)
Lift w/1.6: 0.525" / 0.525"
Lift w/1.5: 0.492" / 0.492"
Lobe Separation: 112
RPM Range: 1500-6000
Type: Hydraulic roller LT4 Hot Cam

Topic: The Hot Cam was designed for use with the LT4 Intake.

The LT4 Hot cam was originally designed to function with the LT4 package, an "anti-tuned" short-runner intake, .100" raised runner 195cc heads. Due to the duration of the cam and the port volume of the heads, it's a safe bet that the LT4 was not designed to make serious power until, I'm guessing, 3500 rpm plus.

If you are familiar with TPI, I probably don't need to tell you that they tend to make peak power below 5000 rpm, and indeed, sometimes as low as 4000 rpm depending upon camshaft, intake flow, heads. So why choose a cam that makes peak power right where the cam wakes up?

A good solution is to advance the cam a few degrees to keep it in sync with the TPI's operation range.Kevin91Z: "...I installed mine 2º advanced because I have the LTR's still, and the cam's peak is higher than the runner's peak. Installing it advanced helps to bring the power band of the cam down a little, and gives it a touch more vacuum, both good things for a speed density LTR TPI."

Keep in mind that the HOT Cam is rated at 218/228 @ .050" with 1.6 rockers. 1.5 rockers will slow the opening of the valve, thus decreasing the duration of the cam @ .050". To approximate the change in duration, I just pretend the graph of lift vs degrees of rotation is sinusoidal (In reality this is not the case, but in the initial stages of lift it provides an adequate approximation), yielding about a 2 degree change in duration, a little more TPI friendly.

This brings up the point that the ramp angle of the HOT cam was designed to be used with 1.6 rockers. GM engineers have a tendency to be conservative when designing production camshafts. As such, they won't be apt to push aggressive ramp profiles for fear of destroying lifters or valve-springs. The cam was designed to make power at a higher RPM thus, the faster the lifter was forced to climb up the ramp. As the lifter approaches the top of the lobe profile, Newton's law states that that lifter is going to want to keep travelling upwards (A body in motion wants to stay in motion). The more aggressive the ramp profile, the more likely the lifter will be to jump off the cam lobe and cause valve float. The point is, the ramp angle was designed for use with 1.6 rockers and to be effective at high RPM.

TPI thrives on aggressive ramp profiles. The low rpm operating range allows for aggressive profiles without risk of valve float. Also, the ram charging effect of the LTR's is increased by allowing the intake valve to stay open until the last possible second, maximizing the "inertial supercharging".

The induction pressure waves of the tuned port system are not even considered in the design of the LT4 HOT cam ... but does it really matter? TPIS took the ZZ3 cam, played around with the lobe center, revamped the exhaust and changed the intake profile slightly, and turned out the zz9, arguably one of the best LTR cams out there. Did TPIS break out the Airflow dynamics book to analyze the resonance effect of tuned intake pulses. Likely not as they are a family of machinists who spun off of a machine shop. Does Comp Cams pay any attention to these resonance effects? Likely not.

So, can anyone tell me why Jason Aschle, Kevin 91Z, and Mike Davis are all running in excess of 107 mph in the quarter with the HOT cam?

------------------
355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Tremec TKO
Pro 5.0 Shifter
GM posi 3.42 rear
Hurst Roll Control
13.9@102
http://www.geocities.com/thetpiguy/index.html
chemjoker@aol.com

Willie

iTrader: (1)

Can anyone give me:

IVO
IVC
EVO
EVC

for the hot cam? It's listed on the cam card, assuming you get a cam card with GM cams???

I cannot realistically compare cams unless I know these figures. Thanks.

------------------
Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
ATI D1SC (10-psig): 12.056 @ 116.62 mph.
Stats are altitude corrected for 3,100 feet using NHRA's Altitude Correction Table.

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

1bad91Z

iTrader: (1)

Why waste your time with the LT4 hot cam? SLP and CompCams both make a cam with these specs (I have the SLP in my new short block): .502/.510 lift w/1.5 rockers .536/.544 w/1.6 rockers, 224/232 duration @.050, 280/288 advertised duration, 112LSA. I dont have the other specs memorized yet, but I can get a part number if ya like. This cam should make a little more power than the Hot Cam.

Willie

iTrader: (1)

SLP and CompCams both make a cam with these specs...

I can get the specs I need for these cams from the respective manufacturers. I cannot get these specs from GM for any of their cams, including production pieces. In order to have a true comparison, I need these specs for the hot cam.

FYI, it is not only lift, duration and LSA that are important. Valve timing events, IVO, IVC, EVO & EVC are equally pertinent. Although published figures are comparable, valve timing events are key to determining power and torque levels. That's why I need them.

Willie

Mark 89Formula

TPI Guy, you make some good points relative to operating range, valvetrain dynamics, and resonance tuning. There's one thing I'd like to point about duration specs though. Duration is measured at a specified tappet lift value, not valve lift. So duration at 50 is really a measurement of how long the lifter is raised .050" or greater above the base circle. This means duration at 50 is independent of rocker arm ratio. This is not to say that going from 1.5 to 1.6 rockers doesn't impact the time the valve spends off the seat (as well as height), just that the published duration is unaffected.

Willie, even if you were able to get your hands on accurate valve timing events, it's not sufficient to accurately model a cam to the accuracy you desire. The fact of the matter is that two cams with similar seat-to-seat timing events can still perform quite differently in the real world even though Dyno 2000 would lead you to believe they're identical. The difference is the lobe profile and resulting valve acceleration. Try this. Run Dyno 2000 for any given engine combo with a hydraulic tappet cam to establish a baseline. Now change the lifter type to solid then roller. See the difference in torque/power even though the other cam input data didn't change?

To gain more insight than the garden variety specs, also look at duration at .200" tappet lift. Comp, Crane, and Crower (and probably some others) all publish this data for their lobes. If you want to compare cams with similar .050 duration values you can subtract the .200" value from the .050" spec to get a measure. The smaller the number, the more aggressive the cam. It's definitely not the whole story, just another parameter to consider when evaluating cams and understanding why some seemingly similar grinds just seem to consistently perform differently.

I'm convinced the HOT cam is more aggressive than many other similar sized cams, so it's not really an apples to apples comparison to say that other similarly speced cams will behave the same. The thirdgen members mentioned above have proven that it works better in a fully worked TPI (heads, base, runners, ...) than conventional wisdom says that it should.

Comps Extreme Energy lobes and Crower's new line of EFI cams also look like great designs that combine short seat durations for good idle, vacuum, and low end torque without compromising mid and top end power like you would experience with a less aggressive profile. Enough rambling for now.

kevinc

I need to update the timeslip on my spec page, the 102.3mph run is old. In cooler NJ weather it pulled 13.1x @ 102.7x (can't recall offhand).

Not sure what GoFasterFirebird's point was...given that he's almost 3 tenths slower than me un-juiced. Maybe "yeah, you're faster than me, but my cam's still better."??

True, the LT4-HOT wasn't designed for TPI. However...timeslips talk. Not just mine, but the others referenced above.

1bad91Z's bench racing text "should make more power than the Hot Cam" belongs in the Theoretical And Street Racing forum with the rest of the noise.

------------------
1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

GofasterFirebird

iTrader: (3)

I really am not concerned with 3 tenths. I use mph as an indication of HP. Kevin, it is obvious that you have better traction than me but can't achieve the MPH that I can. So my car makes more horse under the curve assuming similar weights. Somehow I think mine weighs more than the less than 3300 you claim. I am not saying that my cam is better but how can I say it is worse? Judging by the specs, it would be small in a 305. What advantages would I see with a HOT cam? My car will run less MPH? Yet, as stated earlier, some thirdgenners run respectable mphs with that cam.

Acceld Z

Why don't we try to keep this civil so that maybe we can all learn something. That's why i'm here

kevinc

I'm not trying to sell anyone on the HOT cam. The original poster wanted to know "what you guys are running with a HOT cam" and I answered.

HOT been proven to work even though it's not optimized for LTR induction. I'm always on the lookout for actual performance data on other cam grinds for my next rebuild...there's gotta be a few more tenths or MPH in there with the right cam.

And GoFasterFirebird you need to check your math. You're half right in that I "can't achieve the MPH" that you can...your signature says you're at 102 and I'm slightly over 102, so I'm achieving more MPH than you are. :-)

I'm headed to Cecil Dragway on Saturday and hope to have an even better timeslip to post.

------------------
1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

TRAXION

I wanted to update KevinC's post since his update got wiped. At Cecil he ran 105mph. The other news is that Mike Davis ran 11.9@111.5mph with his LT4 HOT cammed ZZ4 Large Tube Runner setup. The HOT cam can be a great cam. Just depends how you use it. Mike D has a siamesed base and AFR190 heads.

Tim

GofasterFirebird

iTrader: (3)

Kevin, I have ran more than 102. Almost 104. Just the particular time I ran 13.5 something I only ran 102. My launch was just better that time.

kevinc

105.05mph last weekend after a little software tuning on the ol' ECM.

More to come, ALDL shows it's still a tad lean on the PE tables (860mV on the O2 sensor) and my launching needs work.

HOT cam is good, mmmmmmkay?

GofasterFirebird

iTrader: (3)

Dude, I am just trying to figure out if I should buy it. That is why I am skeptical. Think I should buy it? Comments?

kevinc

Don't know about your engine specs, but the bolt-ons are pretty much identical...Edelbrock TES headers, Accel intake, etc.

By way of adding data, mine passes NJ treadmill emission inspections easily even with no EGR. Idle is nice 'n lumpy at 725rpm, gets 30mpg on the highway with the T-56 trans.

I had to do a *lot* of software tuning and chip burning to get here, even before switching from MAF to Speed Density. The more radical the cam, the more software tuning needed to compensate for it.

I don't feel right formally recommending it, given that it's really not designed for a long-tube TPI induction system, but if I was building another engine I'd go with the HOT cam again.

In your case, I'd also swap the AFR springs for either GM LT4 springs or aftermarket pieces. Mike Davis found the AFR stockers needed shimming to get seat pressure right, it was experiencing valve float above ~5000rpm as delivered from AFR. May be attributable to the aggressive lobe ramps mentioned earlier.

Yelofvr

Did you guys see the article in Chevy High Performance on the SD Vortec TPI base?? I thought the "Hot cam" performed INCREDIBLY!!!! I mean it made more HP and torque EVERYWHERE versus the ZZ4 cam or stock L98 cam. I too thought that it was "too much" cam for a long tube setup....... Guess NOT!!! I have a very renewed interest in this cam after seeing those dyno curves. TPI Guy, I really enjoyed your inputs on the topic.

Jim85IROC

iTrader: (2)

This is interresting. I don't have the LT4 HC, but my hydraulic cam has similar lift/duration/LSA numbers. 124/224, .442/.465, 112lsa to be exact. If nothing else, it gives me hope that my setup will run some good times if I ever get my computer issue straightened out.

Of course, being a hydraulic cam, the ramp profile certainly isn't nearly as good as the LT4's.

Scott 88 GTA

ET and link to dyno graph are in the sig. I should easily be able to make it into the 12's whenever I get enough money to ditch the stock torque converter (1300 rpm) and stock intake. Of course then I'll have traction problems.

Matt87GTA

Just FYI, the LT4 Hot Cam is a Hydraulic Roller camshaft.

N8Miller

How do you think that the LT4 hot cam would work with the set-up below? the only major differences is that it would maybe have a 750 carb on it when the cam goes on. thanks

poncho9789

I am planing on running quite a bit faster than that.

poncho9789

That is what he was saying his is a hydraulic tappet and the lt4 hot cam is a roller and the ramp on the hot cam is better for that reason.

Jim85iroc: your cam isn't anywere near the hot cam the specs on the hotcam is as follows:

intake exhaust
218 * 228* @0.050"
279 * 287* @lash
.525" .525" lift
112* lobe seperation angle.