I will be installing a set of heads ported by Lloyd Elliot with the 2.00/1.56 valves. They should flow about 275/190 peak.

I am trying to decide on a cam to best work with these heads and suit my needs. THe car is a daily driver, so low rpm throttle response and driveability are important. I will be going with a 114 LSA on either of these to reduce overlap.

I must emissions test, so the cam must be able to pass the sniffer with a leaned out tune if I fail the OBD2 diagnostic test.

I do not want to rev the stock shortblock past 6000 to make power....perhaps a 6250 redline max. This requires me to stick to the 224 range on the intake duration...any more and it would begin to move the HP peak too high.

I want to use the XE lobes as well. Using Engine Analyzer the 224/230 makes more low RPM torque with no deficiency at higher RPMS...makes me think the really big intake/exhaust split of the 224/236 is unnecessary because the heads have a good intake/exhaust flow ratio already.

However, I've looked at a 224/236 on a 116LSA, which gives it the same total overlap in degrees as the 224/230 114LS but produces about 10ft lbs more torque from 3000-3500 than either the 224/230 114LS or the 224/236 114LS. So that makes the 224/236 116LS look good on paper but real world application is a totally different scenario. All three seem to produce the same peak HP/TQ at about 5800 rpm.

I know the 224/236 is a blower/N20 grind, is anyone running this cam N/A and have track/dyno results?

 

See my sig for a data point. For a real daily driver, I wouldn't want any more loss of drivability than my own set-up. Honestly, if you want to keep things at a 6000 rpm max, I'd go with the Xtreme 218/230/114 cam. A lot of people have run low 12s with that cam no problem and easily pass emissions. It also is much happier to lug along at 1200 rpm or so than any of the cams that you mention. BTW, I'm shifting at about 6300 rpm at the strip.

 

Thanks Rich. Anybody else?

 

I'm lookin at the same two cams for my 94 Z-28. I may go with a blower in the future so I may get the 224/236 just because that is what it was intended for. I'm getting my heads done by Lloyd also. What kind of combustion chamber volume are you gonna go with? I may go like 53 cc's for now and just get a second set for the blower.
Later,
Tom

 

I'm not going to have them shaved any. Just going to go with the Impala .029 gasket which should achieve an 11:1 CR...that'll be plenty for me.

 

I just wanted to add for the benefit of those reading this that duration at .050 isn't the only thing to look at in a cam. Intake center line will determine the powerband of the cam almost as much as the duration.

And interestingly enough, the 224/236 looks like a big split, but if you look at the advertised duration it is 276/288. Still a 12 degree split, but then look at the advertised duration of the CC305 220/230, it is 276/290. So at very low lift the 224/236 is actually slightly smaller than the CC305.

 

Ok so help me out, I'm in the same boat as you. First I want to make sure I can pass emissions. I am having my heads done by the same person as you and I'm looking at the same two cams. What cam would yield the most power for me? I'm not afraid to rev this thing at all. She's very strong.
The only thing is I may go to a blower down the road. Pretty sure I will eventually. So which one is best for me? I dont really know anything about cams except everyone says these two are the best for the LT1.
Tom

 

To be very honest its going to be really hard to pass the sniffer test with either of these cams. It would be best if you could run a leaned out program for the test.

What I have noticed is that the 224/230 114LS 110 ICL and the 224/236 116LS 110ICL have almost the same amount of overlap and will have a very similar powerband since the intake lobe will be in the same spot for both. Engine Analyzer shows the 224/236 putting up 10-12 ft lbs more torque between 3000-3500 rpm, but other than that the two cams produce basically the same power.

Don't think of LSA as a static number. 114LS on a 210/220 cam is not the same as 114 LS on a 230/240 cam. LSA is the distance in degrees (crank degrees I believe) of the centers of the intake and exhaust lobes. But the important number is total degrees of overlap. A bigger cam with the same LSA will have more overlap just because the lobes are fatter. So you might look at that 224/236 116LSA and think the lobes are spread too far, but the overlap is the same as the 224/230 114LS, and the intake open/close and exhaust close are the same for both cams. by using the 116 LS and 110 centerline it really is just opening the exhaust valve a little earlier before the power stroke is completely finished. The 224/236 on a 114LS and 110 ICL has more overlap than the other two, because the lobe centers are spaced the same distance as the 224/230 but the lobes are fatter. This is going to make it tougher to pass emissions and low end torque is going to suffer more, but it would make a little more peak power N/A.

Honestly we are getting into areas I really just don't know about. You can read books, run programs, etc. but it comes down to unfortunately trial and error.

 

I will probably go for the extra torque rather than the higher revs. I have desktop dyno but i cant figure out how to change the cam data. PITA if you ask me.
So maybe I will look at the 224/236 on 116 w/ 110. Sounds good. I like to be different anyway. Everyone seems to be running the 306 cam. Maybe I can get a little more power than them.
Thanks,
Tom
----keep me posted as to what you decide.
cavalrykennel@yahoo.com

 

Desktop Dyno is a fun program, but its not super accurate. I'd caution against making my decition based on that software.

The CC306 is popular, but the XE lobes are far better IMO. They open the valves faster which is why for the same .050 duration the XE cams usually have a smaller adv. duration. That gives you two options: Get an XE cam with similar .050 duration, which will give you similar power w/better driveability, or get an XE cam with an adv. duration that matches the other cam, which means you will get more duration at .050, which will give you more power with the same driveability.

 

Basically I want the most power while still passing emissions.

 

I would go no bigger than a 224/230 on a 114LS then.

 

According to my math you have 69% exhaust/intake ratio. In my opinion mid 70's is a "good" flow ratio.

I've been very happy with the XE cams. I have ran both the XE 224/230 and the XE 224/236 in my car, but with 112 lsa's. The 224/236 didn't seem to build torque quite as abruptly as the 224/230 but was more willing to rev higher... it seemed just a bit peakier. All I have to back this up is my butt-o-meter and Datamaster dyno data. I think the 224/230 is best for A4 and the 224/236 is a good cam for M6's.

Wayne E was running the 224/236 to the low 12's NA. A local guy here with very mild head work and all supporting mods is running low 12's but with 114mph traps. He doesn't even have it tuned well at WOT (been known to fumigate those behind him) and it's pretty much just valves and some bowl work on the heads.

Sounds like you've done your homework and realize how little the "split" actually is with the XE cams. The only thing that'd make me consider going with the 224/236 on your car is the exhaust/intake ratio. Normally for an A4 with full exhaust I'd say 224/230 all the way.

 

Thank you for the input. I agree, the 69% isn't great, for some reason I was thinking the % was better than that until I punched it into my calculator.

So the 224/236 is beginning to sound like a better choice...now the question is what LSA? 114 or 116? 116 will have better idle vaccum and better street manners, but its a question of how much peak power I'd give up.

 

I might still swing towards the 224/230 but I have to disagree with you on some points.

The STOCK heads are just shy of 72% exhaust/intake ratio. Port effeciency is ALWAYS important but to say that 60% is acceptable on any LT1 head is ridiculous. 69% isn't the end of the world for an LT1 head, but even for NA it's best to be in the low to mid 70's, IMO. This should be attainable without hurting port effeciency if the porter knows what he's doing. This "Lloyd" is probably much smarter than I but all I have to do is look at the flow sheets for successful LT1 heads out there to make me feel confident in saying so.