LS-Five

I was considering putting a LT4 hot cam kit in an LT1 project that I am working on. I was just curious how much fuel mileage I can expect to lose. The car will be a daily driver and these days every MPG counts!

Also, what is the lobe separation on this cam? I couldn't find that spec. I know that usually has the most effect on fuel economy.

Anyone know who has the cheapest price on these kits?

Thanks!

Achilleus07

I would say go with Summit....... http://store.summitracing.com/partde...5&autoview=sku



Hotcam wise-
Duration at 050 inch lift 218 int/228 exh
Advertised Duration 279 int/ 287 exh
Lobe Separation (degrees) 112

Not sure about mpg...havent installed mine yet to find out. I would say if you did lose anything....it would be too small to notice...but wait until some else who knows more pipes in.

redvette6spd

With a tune you should gain mileage if you can keep your foot out of it

96er

Will this cam kit require any fueling changes?

Darkgh0st

I have a hotcam w/ ported heads. 26MPG highway / 17.5MPG Overall

MTVette

I did the HotCam kit about 15 months ago. With the reduced friction from the roller rockers, any change in gas mileage on the highway was negligible. City driving mileage was reduced, but that was due more to the high stall TC and increased spirited driving.

Darkgh0st

Gotta run 94 octane to prevent knock. You could get away with 89-91 before cam swap

LS-Five

Ok, stupid question, why does a cam alone cause detonation? I thought that was more a function of compression ratio...

LS-Five

Do you know what you were getting before the swap?

LS-Five

So far, it looks like Sallee-Chevrolet has the lowest price at $560.00 This is just a few dollars cheaper than Summit.

*CORRECTION*

I just looked at Pace Performance and they have it listed for $529.95, for those of you who may be interested in purchasing one.

Darkgh0st

Not sure, someone that knows what they're talking about will chime in. That info is what someone told me.

Darkgh0st

About the same MPG

VR'92

I have seen no real difference with my hotcam swap. Now I'm sure its a little less but honestly I can't tell.

Achilleus07

Well if you want to go cheap cheap you can go on Ebay and pick it all up...I just go with Summit because its now close by my house and on top of that I've never had one shipment screw-up mailwise....other stuff I have bought in the past from other places I have had long wait times or missing parts. Just my two cents. Just keep looking around...You might find one under $500.

96lt4c4

The way I look at it is, if you have a higher lift cam you are opening the intake valve more. Which means you are suckng in more air and fuel into the same amount of space you were with the other cam. So you are squashing more air and fuel in the same chamber. If you were allready on the edge of det. with the old cam then you have just raised your chances to det. You may have to run more octane.

Dr. Evil

I got 30.3mpg all interstate from East Tenn to Harrisburg, Pa with a stock LT4. I got 29.7 on the same return trip. 1000+ miles round trip

Added 4.10 gears and got 27.5mpg from here to Atlanta, 26.9 on the way back. 400+miles round trip

Added hotcam and with the stock tune got 27.3mpg from here to Bowling green. 300+miles

Had a tune from PCMFORLESS installed. No long road trips yet but looks like I'm getting about 23mpg avg on my way to work and back and thats a 40 mile one way commute, mixed driving. 2/3s hwy, the rest stop and go.



A cam change like the HC will not cause any more detonaton problems. My wife as forgotten and put in 87 octane several times before and the car runs fine.

LS-Five

So far, it seems that the general consensus is that there is no signifcant drop in fuel economy with the cam swap. Errr, that is if you can resist the temptation to keep your foot out of it..

Has anyone out there had a different experiece?

93 ragtop

Yes, this is something that my first tuner obiously did not understand. Thank God that pcmforless straightened it out for me.
On the 94-96 you can get away without a tune a little better, but it is recommended. The 92-93 have speed density and run rich at idle and part throttle without a tune. The 94-96 use a MAF system and it can compensate some for the cam change but not enough.
If you go to all the work to put a cam in, spend a little extra, less then $200.00 and have it reprogrammed.

dizwiz24

I have had a drop in fuel economy with the hotcam kit.

The drop in fuel economy started with the hotcam kit, ported heads and Ed Wright tune in my 93 ZF6 vert in late 2001. Later on, I went with LT headers, lightweight AL flywheel, no cats, no EGR, etc. The bad mileage continued.

I get 16.x MPG mixed city/highway. Pure highway mileage is about 24.x MPG.

The bad mileage started with the hotcam kit. Other than what the MPG readout said, I did not track it before I started modding. Before I started mod'ding I would get 17.x to 18.x something before the mods cruising in the city. 19.x with mixed city/highway driving and 25 or so with pure highway. 16's was unheard of.

As for getting better gas mileage with more duration cam, I highly doubt it. Think about it, you are keeping your valves open longer, lower vacuum (so your fuel pressure regulator increases the pressure), more filling of the cylinders with fuel.

Of course O2 sensors 'see' what is happening during part throttle driving and should correct for this...

-------------------------------------------------------------------
Ive replaced my O2 sensors with heated O2 sensors (yes, the heaters work). no luck. The car pulls acceptable vacuum (I think it was 17.5 in. Hg or something) at 900 RPM idle if that sounds right. I would have to double check.

Fuel pressure is 38-40 psi during normal driving.

I may need to check my injectors to make sure they arent leaking or anything, although my electric fuel gauge does not show a system pressure drop for a good 10 minutes after the engine is shut down (key on).

I did just get a new tune so we'll see what happens with mileage.

Corvette Kid

Currently w/ a Hotcam, fully ported heads and intake, oversized valves, 11.3 CR lightweight pistons, balanced of course, headers, good exhaust and a great tune, I get about the same mileage as stock on the road and almost as good in town. Now I'm curious how going to a 388 block will effect this. We'll see....