Comp 3714: 222/222 566/566 with a LSA of 112+4

What will the LSA of "+4" get versus a LSA of say 116?

 

It sure is, but your not going to gain much

Do at least the TR224 on a 114. you'll love it and it passed emmissions in NY and VA for me

 

yup tr224 all the way

 

I have a TR224 on 114 and wouldn't go any smaller. It's a great DD cam and can make great power with some heads.

 

The TR224 sounds good, now I just need to find one cheap. Does the 114 LSA have much lope to it? I don't want much lope or much overlap. I've had bad experiences with high and even medium overlap cams.

 

The plus four means advance; it doesn't means 112 plus 4 = 116. So, the short answer is that it'll peak much sooner than a 116 and have a lot better torque due to higher relative cylinder pressure. I personally think an F13 230/232 112+4 will be a better daily driver cam than anything else mentioned in this thread thus far and give significant power throughout the power band.

But, back to why the 112+4 is better than a 116... or why a 108+0 or 110+0 is even better. Two reasons (actually three if you count overlap): valve events and dynamic compression.

First, the valve events. A 112+4 means the intake centerline (ICL) is at 108 degrees. A tight ICL means the intake valve closing (IVC) will come much sooner, meaning that a given camshaft profile, say 230/232, will peak sooner at 108 vs 112 or 116 if the IVC is set there (but please do not compare a 222/222 112+4 and a 230/232 112+4). By contrast, advancing the cam moves the exhaust closing (EVC) later. So in that case, the exhaust centerline (ECL) would be 116. An early intake closing and late exhaust closing means torque, but not high RPM horsepower, because cylinder pressure is allowed to build during the stroke when no air is entering or exiting the cylinder. Such a setup makes good torque and noses over quickly after peak and usually peaks early (unless the duration is expanded greatly, and high duration and tighter or numerically lower LSA means more overlap; overlap produces power but kills drivability - essentially it moves the vacuum up the RPM band). With an advanced cam, the air is compressed; creating heat and dynamic pressure for torque and that is the second point: dynamic compression.

The dynamic compression ratio (DCR) is a function of the valve events and is more relevant than static compression or what you hear as 10.1:1 for the LS1, 10.5:1 for the LS6, and 10.9:1 for the LS2. More dynamic compression means more torque and power, but it also makes a system more susceptible to low octane fuel, too much timing, or high ambient temperatures. For a cam only swap, any cam above 220 duration will drop the DCR, because the valve events are designed for power and because the duration is always bigger than stock by enough that the LSA isn't tight enough to offset this. The cam will "bleed off" the compression (so a lot more compression could be run with a very aggressive cam on pump gas). But such a cam will gain quite a bit upstairs, because the cam profile is moving air in and out efficiently in the higher band to make more power. If the LSA was tighted up to bring the DCR up, the side effect is of course overlap. Overlap would increase even further reducing the vacuum at idle and low RPM driving. Streetability would be compromised, and for many tuners, their off-the-shelf grinds balance streetability with power. That's why most cam only setups don't gain much or lose some torque over a stock bolt on car, because the dynamic compression is not upped for fear of killing drivability with overlap (though tuning allows a lot of that to be corrected).

A way that tuners have made it so they can have their cake and eat it too is to advance the cam. Advancing doesn't increase overlap, but does increase the DCR. That's why a lot of the bigger duration cams come advanced. A 230/232 on a 108+0 would make better overall power, because it will pull through RPM peak and make killer power in the midrange. It has better valve events for that (later IVC and earlier EVC = better air pump), but the overlap will be high enough to make it less than perfect for streetability. And a 230/232 112+4 will make the same peak and have the same if not better power under the curve with better manners, but won't pull from 6300-7000 like the 108 will. Yet, it will sell better than a smaller cam, because it will be easy to drive and make a better overall and peak numbers than a smaller cam without giving up much, especially compared to how the 108+0 would drive in comparison to a 110+0 222/222.

 

Wow, thanks for the in-depth explanation. I'm all for making great power up top, but like you said I (like many other DD people) would prefer the low and mid-range torque and power. Plus, I want to make sure the cam I choose will work well with the killer summer temperatures here and also not be too bad on mileage. Also, I don't want to have to run premium (only 91 octane here anyway) all the time. I would like to be able to get away with 89 or even 87 octane if I baby it. This would be with 10:1 compression. So, from your reply it looks like I'm more suited for a 112+4 type cam than a 112+0 or 110+0. Right?

 

I am running Patrick G torque cam. My car is not a daily driver but it could be without any problem. 228/232 588/592 110+1, Installed with 4* of advance. 330RWTQ at 3000 RPMS. Surprisingly smooth. Very easy to drive, and I can run mid 11's all day.

JakeFusion has his **** together though. Great explanation.

J.R.

 

wow what heads are your running? that cam sounds like my dream cam

 

Good daily driver cam can be different to different people... Heck I daily drive a GMPP ASA Cam 225/235 .525/.525 110lsa, it's a bit tempermental but I manage. though I'm lookin at somethin now with a lil more lift and dur and a wider lsa.

 

Just curious, what are you trapping? I went with his exact grind (224/228, .641/.646 110LSA, LSK lobes) and have some CNC'd heads (don't know brand or flow #s) with full bolt-ons.

Went 12.3@118 with a 2.0 60' on bald Nittos. Can't put my foot down all the way in first without breaking the tires loose in the mid-upper RPMs. I expect solid mid 11s with a good tire, and especially with a gear.

My dyno chart is attached. Speed Inc had it on the rollers for the 3 runs before they told me it was done, and they only tuned from 2900-6400 it appears. I tried to get them to re-tune the lower end but they told me it was okay and any surging issues I have are "because of the cam" *sigh*

Anyways, the #'s are pretty decent. These numbers with through the Magnaflow exhaust. The track times were done with a cut-out. Made a hair over 340rwtq @ 3000rpm. Shift light is set at 6300

I've got a 12-bolt with 3.73s in my garage, but I may be selling it to buy a new 9" with 3.90s. Will be on nothing less than an ET Street next time at the track, and the plan over the winter is a ported Fast90 with ported LS2 TB (or NW90), 85mm Z06 MAF, and a few induction/airbox mods. I figure with that and the cutout open, it should make somewhere around 460rwhp or so, maybe a little bit more. I figure that will put my low 11s and then the next step is a direct port 100 or 150 shot til the motor blows.