Carbureted LSX Forum - Thoughts on 111 LSA on carb APP.




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BTLFEDSS
02-04-2012, 09:51 AM
Just as the title says just wondering what you guy's thoughts are on a 111 LSA?? I realize a 110-108 is probably better but just curious of your thought on runnning 111 with a carb???


richard david
02-04-2012, 10:04 AM
My first cam was 112 with Carb and it worked fine. Change to a 109 and pick up 3tents

bitterman
02-04-2012, 10:40 AM
the custom carb cam I was spec'd is @ 111+4 but LSA is just one part of the equation.

B


ZONES89RS
02-04-2012, 10:48 AM
111 is better than 112+ in most carbed applications. That simple.

Prorac1
02-04-2012, 10:52 AM
Some of the carb specific cams go down as low as 106 installed. But, depending on the piston and heads, becareful how tight you go, as flycutting may be required. It all depends on what you want and what your willing to put up with. The carb database sticky at the top of the carb forum page is an INVALUABLE source of information on this subject. Best of luck with what ever cam you choose. Eric L

Fbodyjunkie06
02-04-2012, 06:56 PM
My first cam was 112 with Carb and it worked fine. Change to a 109 and pick up 3tents

This should be your tell all right here bottlefed. Carbs and single planes like tight lsa's.

If you were going to spray it I would say the 111 would be ideal, but if it's going to be strictly N/A go tighter around 108-109.

speedtigger
02-04-2012, 07:21 PM
Narrowing the LSA increases overlap. On cars with good and proper headers and free flowing exhaust, the scavenging effect of the headers increases the intake pulse in the midrange. This boosts the midrange power. The increase/advantage is exaggerated on cars with large volume heads and/or short runner single plane intake manifolds. This is why you see narrow lobe center cams being recommended and run on drag cars with single plane intakes. Cars with automatic transmissions tend to prefer a narrower lobe center than a stick shift car.

The above information is not specific to LS motors. We have know this for decades. However, the LS motors appear to be no exception.

ZONES89RS
02-05-2012, 03:20 PM
I have seen allot of tighter lsa motors get hit with notrous and do just fine, the ones that did not do so well happened to be simply blowingthrough the converter, lol.

pairof69s
02-06-2012, 12:59 AM
good info:corn:

The stunningman
02-06-2012, 07:46 AM
I have seen allot of tighter lsa motors get hit with notrous and do just fine, the ones that did not do so well happened to be simply blowingthrough the converter, lol.

They did fine but they were feeling 100hp hit on 150 jetting because of the valve timing.

1badeagle
02-06-2012, 08:52 AM
My carbed cam for a 200 hit from Patrick G is a 110+4.

ZONES89RS
02-06-2012, 05:45 PM
They did fine but they were feeling 100hp hit on 150 jetting because of the valve timing.

Any proof to back that? I can believe it at lower revs, but at higher RPM, where the events happen at a increased rate, it may very well not be so. If a tighter LSA brings TQ in faster on motor, it may bleed off some power from nitrous, but on the bid end, i find it not so easy to believe it is not getting the most from it.

I have several build forged nitrous motors with the old SBCs and are on a 106, they run pretty damn hard, gaining allot from small 200 shots.

Mako77
02-07-2012, 01:15 PM
that being said.... am I screwing up by running am efi cam in a carb app? The motor happened to come with a 224/228 581 588 on a 114.

speedtigger
02-07-2012, 02:12 PM
that being said.... am I screwing up by running am efi cam in a carb app? The motor happened to come with a 224/228 581 588 on a 114.

You should start your own thread on the topic and list all of your set up. Then people can comment without hijacking.

Mako77
02-07-2012, 05:28 PM
k sorry. thought it might be relevant.

speedtigger
02-07-2012, 06:17 PM
No worries man. Just a way you can get everyone's thoughts for your particular application.

The stunningman
02-08-2012, 08:12 AM
Any proof to back that? I can believe it at lower revs, but at higher RPM, where the events happen at a increased rate, it may very well not be so. If a tighter LSA brings TQ in faster on motor, it may bleed off some power from nitrous, but on the bid end, i find it not so easy to believe it is not getting the most from it.

I have several build forged nitrous motors with the old SBCs and are on a 106, they run pretty damn hard, gaining allot from small 200 shots.


Anytime you run a tight LSA both the intake and the exhaust valves are opening closer together leaving "both doors open". This allows more of the nitrous charge to slip out the open exhaust valve. Taking power away anywhere in the powerband will affect the whole run. Obviously as you know the narrow LSA actually narrows the powerband, so the whole shot will actually be optimized for a very short distance of the pull. I don't have actual numbers but I have have read up on test done. None of my links are saved but I will try and find one for you when I get a chance.