Several times I have seen reference to LT4 Hot cams. Is this a different or optional cam from the factory? Will an LT1 accept said LT4 Hot cam?

 

LT4 Hot Cam is an gm performance aftermarket cam. It was not an option. You can find an LT4 Hot Cam Kit from Jegs or Summit. The kit will include 1.6 AL Roller Rockers as well. So, yes it can be used with an LT1.

 

Thank you very much.

 

Another option http://www.advancedinduction.com/LTX...adsCamKits.php

 

LT4 hot cam needs better springs when used in an LT1. If u try and use that cam with stock LT1 vlv springs the springs will go into "coil bind". The LT4 hot cam is a great buy at only $225. And even better deal as kit with the LT4 vlv springs and 1.6 roller rocker arms - $560. Problem with using the LT4 vlv springs on an LT1 head is the LT1 vlvs are solid stem vlvs and much heavier than LT4 "hollow stem" vlvs. U shouldnt use the LT4 hot cam vlv springs on an LT1 head - u need a stronger spring. Just my caution - buyer beware.

 

Just the right amount of aggressive idle, and overall improved power too!

Experts might think there are better cams, but I really like mine!

 

This all depends on your goals. The LT4 kit is a very good economic improvement. How far would you like to go?

 

I put an LT4 HotCam into my 1992 LT1 several years ago. That, plus a ton of other bolt-ons gave me quarter mile times in the upper 12's. The other mods included 3.33 gears, high stall torque convertor, long tube headers, electric water pump, and muffler eliminators.

 

Dumb question time, but would just a hotcam on its own (with rockers, springs) in a LT1 give it noticeable improvement?

 

Slightly??? the hot cam is slightly different then the OBD2 LT4 engine combo. Also the heads have bigger valves and better flow, Beehives.
The intake has better flow, the pistons & rings are different has more compression 10.4 VS 10.8, 1.6 Roller rockers, 28lbs injectors. After all this only makes 330HP @ 5,800 factory limited @ 6,300 vs 300HP @ 5,000 factory limited @ 5,750
In short if you do not re-flash your 92-93 ECM / 94-95 PCM your limited to 5,750 falling short of the new peak HP.

 

In reality however, the LT4 dynos just as well as the 350 horse LS1 at the tires.

That 330 was underrated. The LT4 made in reality 345 to 350.
Also I'm not sure I really buy the intake being all that different.
The hot cam itself is also much more aggressive than the LT4s.
The LT4 cam ONLY has a more aggressive total lift than the LT1 because of the 1.6 RRs.
The LT1 cam, is less aggressive than the Hot Cam (and the 1 is more aggressive than 4s...) so there would be a pretty significant gain, after a retune.

 

take a read.
http://www.grandsportregistry.com/lt1vslt4.htm

the LT4 intake is thicker to allow port matching. Also the LT4 has it's own Cam PN: different from the LT1

With a tune!!! there would be a descent improvement. Without. Not so much!

 

My LT4 with the Hot Cam and LT Headers and Corsa Exhaust produced 324hp and 330lbft torque at the wheels with a dyno tune. So best I see it is the Hot Cam with headers and tune will eliminate the driveline loss from the flywheel to the tires of the stock LT4.

I just put my NT 555's back on this past weekend and they break loose in 1st gear once I hit 3500rpm. It makes sense because the dyno shows the torque start to increase at about 3250rpm. From my dyno the LT4 with the hot cam will perform best between 3500 and 5500.

 

http://home.insightbb.com/~nathan.pl..._corvette.html

 

Internet rumors. Show some proof.

I have spent more time researching this internet rumor than I care to think about. There is no data I have found which supports this statement.

Bottom line: GM rated the LT4 and LS1 through the standards set by the Society of Automotive Engineers at the time. No where in those standards is the ability of the manufacturer to lower or raise the rating when or as desired. Additionally, GM had no reason to fluff off the numbers of the LT4 as the LT4 was a low volume and optional high spec build of the LT1. The idea that they derated the 1996 LT4 to help sales of the 1997 LS1 does not hold water. The ratings are what they are.

 

While I agree to an extent I will say your argument doesn't exactly hold water. For instance, my stock 2000 Z28 automatic with 2.73 gears was "rated" with the same rating system as the same year Corvette and my car put down 287/299 with 56k miles on it. A 2001 6 speed Corvette with a cat back and air filter put down 293/303. Same dyno, same day.

Now, granted, GM says due to an inefficient air box and exhaust manifolds the Z28 engine was 310 hp vs 345 for the Corvette. So who set the rating? GM? Did GM have any input on the rating? Doesnt quite make sense, now does it? At least not with your reasoning.

So how is it that the rating system used was equal across the board? It's not, because with drivelind loss my car had far more than 310 crank hp. Yes, the IRS eats a few extra hp/tq in the Vette but not enough to warrant the difference in rating.

 

In no way am I saying the LT4 was underrated intentionally.

 

What are you basing driveline loss on? Provided manufacture's claimed SAE power against individual dyno numbers?

First off, individual privately owned dynamometers are usually not calibrated to SAE standards if they are calibrated at all. Therefore any number provided by these machines are speculative at best and usually a high over estimation of power to make the owner of the vehicle feel better.

There is no scientific way of determining driveline loss for any given car without running the individual motor on a dyno and then running that same motor with drivetrain on the same dyno. Then comparing the two dyno graphs to show a delta between.

Show me someone who has completed this and then you will have your number. Any other argument to the difference is mere speculation and bar top racing. End of story.

 

They have diff part #s, but the actual cam's lift #s are more conservative in the LT4, than the LT1s.
LT1's cam profile with 1.6RRs would generate more lift than the factory LT4.
(Which actually puts it middle of the road between the LT4 and, Hot Cam)

 

Agreed. Let's for a minute think of this in a logical sense. My Z put down just a hair less than a C5. C5 OD that year was "rated" at 350/365. If is a safe assumption that a manual tranny car loses roughly 15 percent, give or take, from the drive line. What is 293/350 and what is 303/365? Math works out to about 16%/17%, respectfully. My Z with its stock rating only lost roughly 7%/9%, respectfully.

Yes, go get exact you need to do engine and then chassis. However, you won't be exact there either because you WILL NOT be able to duplicate the exact atmospheric conditions. So your theory of it as an exact science is shot to hell.

General assumption (quite well known and respected) is the 4L60 eats about 18-20%. With those numbers my car actually performed quite well. I attribute it to the bogus hp ratings that it left the factory with.

But let's step away from the ratings. The 01 LS1 is slightly different than the 2000. Intake, heads (not enough to say so from 853-241), smaller cam, bigger injectors, block slightly revised. Of those things GM rated the Vette at 5 hp and 15 tq more. Since both cara used the same dyno on the same day with the same conditions, you would and should expect to see a mub larger gap if the ratinga from GM were accurate. As we all know, the ratings were not.

Yes, agreed that it would take more than this bench racing to get actual drivelind loss, but one would expect that two cara with very close engines to produce the same hp/tq figures within a certain delta. Which we clearly have. The only issue is the "ratings" they came with. The ratings were bogus for the f-body. That is a fact. So ce the Vette put down right about what it should for well accepted drive line loss I would say the dyno was pretty accurate. It may not be set up and spec'd but its pretty close.

Your science of on the engine dyno and chassis dyno would be ideal if you could duplicate the exact atmospheric conditions. Since you can't.....well, that argument holds as much water as a spaghetti strainer.