I am shopping for a cam and still don't understand the benefits of going with either equal duration, split or reverse split. I have read J Rods long cam thread and jrp's FAQ but I am still confused.

I am looking at semi-mild stuff like the TR224, Comp 222/224, G5X1, FM10 and others along those lines on a 114LSA (nice idle) with ported heads and bolt ons (no NOS or forced induction). What can I expect to gain, lose or change by going to a "split" vs equal cam?

Sorry is this is old news to most of you

 

The better your exhaust is, the more a reverse split makes sense for a given drivability goal. The big ole honking splits seem to be making the most absolute power, but you can make very good power with an easier to tune combo using a reverse split, if your exhaust flow is excellent.

TR 224 cam is hard to beat if that is what you're looking for.

 

My exhaust isn't as low-restriction as some are (cats in place) so does this mean I should stay away from a reverse split like the 222/224 Comp?

The TR224 seems to be a real favorite around here. Maybe I should look into the TR227/224?

 

With a catted exhaust setup, I'd steer away from the reverse split idea. Reverse split is where the intake duration is more than exhaust. I think you have it backwards...The single pattern cams are showing some good gains, but I think the best gains are coming out of traditional split dual pattern grinds.

 

With cats a 224/224 114 would be fine. emissions compliant with a simple tune.

 

I've had 15 cams in my car and the worst ones were reverse splits. I would never waste my time installing another one.

 

for a street/strip type aplication, i suggest one of the VHP cams. specifically either the 047 or 062 if you want more lift. huge torque gains along with some horsepower.

http://www.vincihighperformance.com/...%20LS1%202.htm

here's what the 047 did in their test car.
http://www.vincihighperformance.com/...ARPARENT2.HTML

 

I still find their cams amusing. I remember I recommended a hotcam to somebody and everybody said I was stupid. Then he bought the VHP cam that has almost the exact same specifications and everybody applauded him. They probably do make good cams though...just thought I would slip this rant in here.

 

Reverse splits are really designed for stock/mild port head cars with good exhaust systems. Ex: a car with stock heads, mid/LT headers, catback/true duals has really good exhaust flow (more exhaust flow than intake) so the extra intake helps kick things up a bit.

Non split cams work well in cars where everything is even (either both good or both bad ). This usually means good heads and good exhaust (on stock CI motors) where that extra intake or exhaust size won't do much help (balanced system).

Standard split (more exhaust) cams are for N20, FI, higher RPM, and big CI motors where there will be LOTS of gas flowing in and the problem starts to become "how do I get this stuff OUT?". As I mentioned, you need that extra duration at high RPM because it takes "X" amount of time to get "X" amount of gas out and that is harder to get at 7500RPM than at 6500RPM. So you open the valve sooner (open it longer) to get the time needed.


I had a TR224/224 in my old 346 and it worked really well. If you want a little more HP you can go up to something like the TR230/224 as it will help pull in some more air/fuel. If you are going to turn up higher RPM (7K+ RPM) then you might need to look into some extra exhaust duration.

 

Thanks for the reply Would it be safe to say that a traditional split cam (eg 222/224) would be good in a car with a decent intake and heads (eg LS6 manifold w/AS stage 2.5 heads) but slightly more restrictive exhaust side (eg shorty headers and cats)? Is the extra exhast lobe duration used to "bolster" the lacking exhaust side flow? Would there be a reason to not use a traditional split on an N/A car without N2O?

 

If your plan is to stick with shorty headers and cats (never go mid or long tube) then I would say something with a min of 8-10 degrees extra exhaust would be good.


Just to give you an idea of what I would look at if it were MY car, start with what the TR224/224 on a 114LSA (which everyone agrees a car with Cats can get through emissions on) has:

its valve events are

EVO (BBDC) = 50
EVC (BTDC) = 6
IVO (BTDC)= 2
IVC (ABDC) = 42

this gives -4 degrees of overlap (when looking at 0.050" numbers)



I would look at a 224/232 on a 116LSA

EVO (BBDC) = 56
EVC (BTDC) = 4
IVO (BTDC)= 0
IVC (ABDC) = 44

that still gives -4 degrees of overlap but you will notice the "blead down" is starting sooner and lasts longer so you can make up for the lack of exhaust flow. The stock LS1 cam has a 116LSA also (LS6 cam has a 117LSA) and I think you will want this LSA (gives less overlap) for two reasons:

1) emissions.......overlap is what makes your car "dirty" to the state so the less overlap the better (which is why a 224/224 114LSA does better than a 224/224 112LSA)

2) overlap is done to use a good exhaust's "high flow" capabilities to help pull in fresh air. with a "pluged up exhaust" you will actually be pushing exhaust back into the intake if you have much overlap.



now if it were MY car (because I live out here in AZ where they only do OBD2 tests so sniffer isn't a problem), I would use something like a 224/238 116LSA

EVO (BBDC) = 59
EVC (BTDC) = 1
IVO (BTDC)= 0
IVC (ABDC) = 44

this gives -1 degree overlap (TR224/224 112LSA has 0 overlap)


now.....if you look at both cams I posted (especially the second one....) and then look at the GM cams, you will notice GM did the same thing with their "Hot Cam", ASA, and GrandAm cams. All of their cams are designed with "stock" manifolds in mind (kind of like shorties) so it takes more exhaust duration to get the job done.


note: I'm sure someone will give me a for this but I tried at least .......think over what I said here, read some more, and then Monday get ahold of a company that really knows what they are doing (I like Thunder Racing and Futral) and have a good chat. If you do mention these "cams" I said, either post or PM me as I would like to know what they think (they may also say I'm on crack ).....till then,

 

Could you elaborate a bit more on this?
-What were the problems?

Whats the matter, the PEAK numbers weren't there? Lost your Dyno Queen title

 

the hotcam is not the same as the VHP cam. VE might be the similiar. but, lobe profiles are way different.

 

I want in on this one to...

 

the peak numbers weren't worth a **** and the midrange wasn't all that great either. A reverse split works good up to about 4,800 or 5,000 then it is all down hill from there. If you have a problem with my dyno queen numbers or my track times, you know how to PM me... and I'll be at the thunder shootout *******

I don't have time for ********* and you seem to be one. I can post dynosheets for every cam I've had and show the differences between every one of them. That information is something that LOADS of time and money have given me. It only takes a second or two to make a smartass relply like yours, but it takes months of trial and error along with thousands of dollars to be a dyno/track queen.

 

Gomer.

Calm down, I am only teasing.
I don't appreciate the name calling. It hurts my feelings.

When you say a reverse split works well up to 4800-5000rpm are you referring to the hp or tq? Guessing hp? How was the tq curve?
Would you mind listing some of the camshafts you went with? Maybe so we could do some sort of comparison between such.

One more thing, I forgot to ask. Are you claiming reverse splits work for ****, because of dyno racing, or track comparisons?

Thanks.

 

All the hostillity...That sounds like a good idea. That is, if you have the time and patience to load up those graphs. It'd certainly settle a lot of curiosity in this thread. I'm purdy darn curious myself. Do it for the kids...

 

.... When gomer strikes back!

 

Here's a comparison of a 232/230, 221/221, and a 230/232 on my car. The only changes were 3.42 gears for the 232/230 and 4.10's with the other two cams. I tweaked the A/F for each one a little bit, timing remained the same. These runs were with open cutout and all belts on the car. Complete cam specs are below
232/230 .580/.580 110lsa 108icl
221/221 .553/.553 114lsa 110icl
230/232 .59x/.59x 112lsa 110icl

 

hmmm. interesting. happen to know what lobe profile the reverse split uses?

wonder if its a lazy lobe causing the lack of performance. might be part of the problem. or lack of a good choice of VE's were used maybe.

good comparo none the less.