I have seen some pretty big cams like ...... 252/252 .600/.600 on a 110. I will be doing a cam swap this summer along with heads, and have always wanted a radical idle. Would like to know what i could put in my car.

 

ttt

 

Remember that if you go with a cam that big, then you will need to spin over 7k rpm. ON stock cubes and well ported heads, then it will probably spin to 7200 which is the limit of the LT1 PCM. Not worth it IMO. You will not enjoy driving it and will be a dog below 4-5k rpm.

IT just doesnt sound like a good idea. You would need a solid roller valvetrain for that kind of setup anyway.

Any forget closed loop tuning. You will need to run open loop at all times. That cam has 32* of effective overlap, which is absurd.

It just seems like a bad idea is you ask me.

 

You can have a pretty aggressive idle with a cam like the 236/242 with lift in the .575-.595 lift range or something in that ball park on stock cubes. There are many video clips out there of cams in this range you can look at and listen to that will prove the mean idle of these cams on a stock cube engine. I personally like the sound of a large cam in an Lt1 but i like it better when you have the combination of that large cam all working together putting some nice numbers down on the dyno/track. Anyway good luck with your decision.

Brandon

 

everyone thinks that cam sounds massive......i want something around the lines of the T-REX for the LS1. Some big lift. I will be having ported heads, and the short block will be going all forged when it goes.

 

If you're going to rebuild the shortblock all forged, I'd say go ahead and atleast do a 383. Big cams in stock cubes isn't really the best idea... Not any fun when you're car won't idle right and you're in heavy traffic trying to keep the engine running while not slamming into the back of the SUV in front of you, only to do it over again at the next light.. IMO

 

thats quite a bit more to go all forged 383 instead of all forged 355. I might end up just going with the GM 847 or a custom cam.

 

I seen your previous post...... a gm 847 or a cc306 sounds pretty radical

 

yea i think ill end up going with that combo GM847 with the 125 shot.

 

lobe design has alot to do with where the cam pulls from and how far it pulls (rpm)wise.

if your wanting alot of lope then just get something along the lines of the 847 on a 108lsa (and yes they make it)

if your wanting to make the most power with you can with your combo then get a custom grind.

and you can tune any cam for closed loop. and by the way when you tune open loop the pe tables are ignored.

you also need to pick a cam that suites your car like the gears, a4 or m6, dailey driven or what.

and a HIGH lift cam may not be best for your heads you need to get the flow numbers for your head and get a cam to match.

you need to do a litlle more research on cams before you go and buy one. just because you see a cam in catalog doesnt mean its for you.

if you just want a alot of lope get a cam with alot of overlap.

and you may want to brush up on your tuning. thats where the powers at. well that and a good matched combo

 

Not really. If you are already buying new rods, pistons and crank... the only real extra cost would come from the block clearancing if youd even need it. Id say $500 extra at the most.

Big cams sound cool but that is about where the good ends and you are left with neck wrenching cam surge, horrible gas mileage and usable power well outside the RPM youll spend the most time driving in.

 

Depends what your definition of 'big' is. My ~24x/~25x, ~0.600", 110 LSA doesn't surge (tune helps here), has power within the RPM range I drive in (gears and tune help here), and gas mileage - what is that? (gears and driver don't help here).

I don't know very many folks who build big cam strokers and worry about mileage. Maybe I'm off base

 

My comparably small 224/230 110 LSA will surge a little sometimes. Id think a cam of that size would barely idle. Maybe DCR comes into play with the surging issues.

From what I understood he wanted to keep stock cubes anyway. A cam of that size in a 350 is a bit overkill. I guess when gas is $2/gal it becomes a factor in cam choice... did for me anyway.

 

When going with a big (stupid) cam,remember your dynamic compression ratio and keep it above 8.5 to 9.0 or it will run real lazy as to what it should run like. A 250@50 cam should run a 11.5 or better static compression.

 

I was about to mention DCR. On a cam in the 25x range, then it will be lower than you would like and need some serious compression (pushing 13:1) to make the power it should.

Closed loop tuning is tough on a cam like that. It would just pour out gas at any RPM below 2500 rpm even while cruising. It just has too much overlap to satisfy the oxygen sensors. It would take a very good engine tuner to trick the computer to idle and run right. You would need to set BLM boundaries and maxes to keep it under control at lower RPMs or even BLM lockers. You could also tune it to run PE mode idle with negative percentages. Just not the best way to run IMO.

If you are going with a cam that large, then you would want some heads that are better than LT1 castings. LT1 heads even ported by someone who really knows what they are doing, would not make the kind of power to justify it. LS1 heads flow extremely well for stock castings and can be ported out to make even more power. Comparing LS1 to LT1 cams is like apples and oranges.

First off, LS1 heads have better exhaust flow than LT1s do, which is the main reason that LS1 cams often have single pattern cams or even reverse split, which is unheard of on an LT1 for the most part. Plus LS1 heads like lift more than LT1 sytle heads. Most all the "big" LS1 cams are in the .600" lift range. Most LT1 cams are around 550-580. Just dont go trying to copy LS1 stuff and expect the same kinda reactions from an LT1.