Hot Cam Question?

[LT4 -Mike]

I would like to know more about the 'LT4-Hot cam', not Just the spec's, but seat of the pants information.

1. Will it pass the SMOG test (Calif?)

2. What are the H.P. gains and in what part of the powerband?

3. What's the driveability like, is there more power on the low-end,High-end or did you experence any flat spots?

4. What kind of R.P.M. increase, if Any?

5. Would You recomend doing it (love it or hate it)?

6. How did your installation go?

I'm considering installing the Hot Cam in my Vette along with 4.10's in the rear end, but would like some input from those of you who have gone through this.

Thanks Mike

 

[Vettelt193]

I haven't done it to my car, but have to a friends...

1. Not sure, but I am pretty sure it has a CARB number, and is 50 state legal

2. HP gains depend on other mods as well, but figure a solid 30 HP.

3. Driving the car will take a bit of getting used to, it actually will require a bit more throttle to get the car moving from a stand-still... the low end power actually felt a bit reduced, while top end was a huge difference in power

4. RPM can be increased, as the cam is a high RPM cam, you could easily turn a couple of hundred more RPM safely

5. I did not like it, the owner of the car did... he wanted high RPM and high HP... My thought is I use from idle to around 2000 RPM 95% of the time, and the HotCam is weak in that area, so I tend to mod to make the 95% more enjoyable, as well as the remaining 5%, instead of making the 95% less enjoyable.

6. installation was pretty straightforward, but time consuming

the hotcam works much better with 4.10's than stock, so you would have a good combo there.

 

[LT4 -Mike]

Thanks Vettelt193

Thats the kind of infomation I'm looking for, the pro's and con's.

Mike

 

[sothpaw]

another cam?

Vettelt193,

I think in another thread you mentioned that there are other mild
cams out there for the LT1/4 --any specific names?

I'd like to add a cam with my cyl. heads as you recommended, but
the drivability issues you mention here are probably going to
discourage me from going with the LT4 Hot cam.

I hate having to put a lot of throttle in just to start the car.

 

[Springer's LT4]

1) Highly doubtful, it's an off-road cam and even says so on the box. It might be possible to pass with a PCM programmed specificlly for emissions testing.

2) Here are the before and after dyno charts on my stock LT4. The 1st is all stock except for a K&N, after was a the Hot Cam and ported intake. This was still using stock ECM programming

Before
http://corvette.flmisfits.com/images/lt4dyno.jpg

After:
http://corvette.flmisfits.com/images/lt4hotcam.jpg

3) I lost no power down low and picked it all up in the higher RPM's, it drove ok with stock programming on the PCM, but was better after I had the PCM programmed. With the idle set to stock it took a little extra gas to get it going, but with the idle now set to 875 that is no longer the case.

4) The car will make power above the stock rev limiter, some people raise it to 6500-6700, I personally left mine sock, no need to rev it any higher IMO.

5) I certainly recommend it... nothing else will give you that kind of HP gain for that price. (except for NOS of course)

6) I had a guy do my install because I lacked the place to do it, if your good with turning wrenches and never took apart an LT motor, expect a good week to do it and do it right.


Exhaust is next on my list, hope to get close to 360 RWHP with headers and exhaust.

 

[sothpaw]

labor cost?

Springer,
I'd have someone else do the work also. How much did the pros charge you for just labor to
put in the Hot cam? Did they port the intake man. at a local machine shop and re-install?
How much did that cost?

I do have dyno. emmissions testing here; and my computer is programmable only thru a chip.
Does your state not require any emmissions test?

Thanks a lot for posting those dyno numbers. Your LT4 looks pretty hot before the cam!!!

 

[Springer's LT4]

I had one shop do everything including the intake. To install the cam, re-seal the entire motor, port the intake, change plugs and wires and drain the tranny fluid cam to $1200. I provided the cam, wires and most of the gaskets, they provided all the fluids, AC declo platinum plugs and the 160 Hypertech T-stat.

You'll certainly need a chip done for you on an LT1... and I'd most likely buy the entire LT4 hot cam kit which comes with the roller rockers and new springs. I know of some LT1's that have picked up over 40+ HP to the rear wheels with this kit. Might also want to figure in new optispark and water pump incase those show signs of wear when they get in there... both mine were fairly new on my car.

 

[UB2 SLOW]

With the following, my LT1 went from 300hp to just over 400hp. LT4 hotcam(kit), LT4 heads, Taylor 8mm wires, LT4 intake, 52mm throttle body, shorty headers, 30#injectors, underpully, Extreme Duty timing chain(highly recommended) and Ed Wright programing. My 1/4 mile times went from 13.7@100 to 12.5@111. This is on a auto.

 

[LT4 -Mike]

UB2 SLOW,

Wow, that's a great H.P. increase and thanks for the info.
I would still like to here from those of you that have gone through the Smog testing. I live in So. calif. and its alot of work and expence to have to change it all out again just to pass emmissions test.

Great info thanks for the input from all of you.

Mike

 

[sothpaw]

UB,

Just out of curiousity, those were stock LT4 heads and intake
manifold, not ported?

--Now all you need is nitrous!

 

[UB2 SLOW]

I had the heads ported and then had the Intake ported to match the heads and TB.

 

[Vettelt193]

sothpaw: I need more info on what you want... power gains Vs. gas mileage/drivability, and where you want the power (broad Vs. narrow, high RPM HP Vs. low end torque)

Springer has one heck of an engine... I haven't seen any other dynos like that... (there is almost always a loss in low end power, just significant enough to feel) the lower RPM's are almost identical, while the high end HP is much higher.... the best of everything...

 

[sothpaw]

cam

Vettelt193,

I'm coming on here tonight to look at old cam posts--in search of another cam for the LT1.

I'd like to get at least 30 rwhp, wouldn't like any change in driveability, reliability, or gas mileage; probably don't want too loud a sound either (hence not headers and exhaust, at least, for now). The objective is to get from a best of 13.3 s to a consistent 12.9-- hoping
30 rwhp is enough.

As for the power band, I believe you were right in an earlier post in that it's probably not
healthy to rev an LT1 to 6300-6500. Note Springer's cam doesn't gain anything until 5000
rpm--and 11 rwhp of it was at 6300 rpm. So, I'm looking for a cam that would be done it's
job by 5800 rpm, ideally, so I could shift at 6000 (and no need to alter the tach then).

Hope no one is annoyed yet by my inquiries; I really will do something big this Spring.

 

[UB2 SLOW]

Re: cam

[QUOTE So, I'm looking for a cam that would be done it's
job by 5800 rpm, ideally, so I could shift at 6000 (and no need to alter the tach then).

Hope no one is annoyed yet by my inquiries; I really will do something big this Spring. [/B][/QUOTE]

If that is your goal, you do not want a HotCam. They make most of their power around 6000+. No one will get annoyed, trust me, we have all been there.

 

[Vettelt193]

sothpaw:

check this cam out http://www.cranecams.com/master/apps/chevy40.htm#1. CompuCam

if the link doesn't work, it is the crane cams PowerMax 2033. It is much more mild than the LT4 hotcam... you shouldn't lose any on the bottom with this one, and give you more on top. I think it is just enough to get what you want... your approx. 30 HP without drivability issues... I can give you some more suggestions after you look over this one. I just need to know if you want something more mild, more wild, or just different (lower lobe?)

 

[sothpaw]

looked at it

Vettelt193,

Thanks for the suggestion. I looked--I feel too ingnorant though, to tell if this is what I want.
I'm reading up on cams in a book I have--I may need more info. when I'm done.

Did one of your friends use this cam in an LT1? Would Crane have a dyno curve for this
cam installed?

--From what I'm reading, I have to add long valve life to the list of requirements. A little noise
in the train is ok though. I'd like the engine to last another 100-125k miles after this.

Thanks again!

 

[Vettelt193]

I have not personally used this cam, because it isn't very popular... not because it isn't good, but because most people that do a cam want as much power as they can get from it since it does require quite a bit of work.... also, cams are all about the same price, so most just go for more wild setups.

I have heard about this cam at my drag strip, and have not heard any negatives... the biggest positive over the LT4 hotcam is the powerband is much more usable, does not require raising the rev limiter, and does not make driving the car any more difficult.

If you want another 100+k miles out of your car, you have many things to think about (i think i remember you saying you have over 80k now?) Let me know how many miles you have first, and I can talk about a few issues before you go spending the big bucks

 

[sothpaw]

75 k mi

I know the optispark and water pump will be issues in the near
future based on other's experiences. Also, my diff. is making noise, something will need fixing there.

Having read about lift, .050 duration, advertised duration, lobe
separation, and lobe intensity, it seems to me that if I go with
heads + cam, I can use a more mild cam that will still have enough
duration to use the extra flow of the heads. But, if I change just
the cam, I'll need a more agressive cam (more duration and lift,
as much separtion as tolerable to shift at 5800 and use the
high end horsepower).

So those at the drag strip had LT1s?

Do you know of a site that has dyno info? I'm going to look
at the vendor site again...

 

[Vettelt193]

those at the drag strip had LT1's, they were both Z28's though, but, the performance and real world will equate to a corvette LT1.

you are correct in your understanding about the heads + cam. Your situation is a bit different than most though, because you are basically trying to 'back into' 30 more HP, where most are just trying to get as much power per dollar they can.

the cam and heads work together, but do the same things to some level... they both are reasons for getting air into the combustion chamber. more lift, or duration = more air, better flowing heads = more air... a combo of the two is even better yet.

If you want to do heads, and only get 30 HP, you could port/polish them, then throw in an LT4 cam (not a hotcam, just a standard LT4 cam) This would be about as mild as you could go, but not oriented to HP/dollar.

Also, please keep in mind, heads won't come up with a ton of power if you are not running a good exhaust system... The whole engine works as a system... the usual area of attack to find more power, is to get rid of the bottle necks in the system.

One last thing to think about is the parts plus labor cost of the whole package you want.... Heads aren't cheap, and the labor to install them isn't either.... cams are pretty cheap, but the labor isn't... add all that up, and you may find you could just buy a mild supercharger instead, which wouldn't cause any more wear than the heads and cam.

 

[sothpaw]

Did these LT1 guys at the strip use heads+ cam or just cam?

I talked to a quality vendor about heads/cam this am, he quoted
a similar cam to the 2033. But he predicted that the cam alone
on an LT1 would only give 8 hp, as the LT1 heads (170cc intake
ports) are just to restrictive. The LT4, however, will respond
great to a cam, as the LT4 heads are opened up to 198cc.

So, I'll try to get more data, but it's probably cam+heads or
just heads.