You're probably going to need more cam to hit 400hp. I'm expecting 375 to the wheels but hoping if the combo works well to see 380+

Lloyd told me the 224/230 and his port work with the stock sized valves could put down 340-380 depending on state of tune and other bolt ons (headers, etc. etc.). Assuming I could get 370 out of that, he said the bigger valves are usually worth worth 15-18 hp. So, 385 would not be out of the realm of possibility.

 

I guess 385 could keep me happy for a little while.

 

Agreed about Comp. I'd like to see a 216 duration lobe and a 221 lobe and a 233 lobe...something to split the difference between their exisiting XE's.

I'm basically just going to hedge my bets on the emissions. I think I can lean it up enough to pass if it happens to fail the OBD2 test. But if I cannot make it pass I will just register is at my sister's house in Clarksville (no emissions there) or at my parents' house in KY.

And as far as other catalogs. I've gone online and found adv. and .050 duration and lift for most of the populat LT1 cams out there from Comp, Crane, TPIS, GM, Crower, etc. and put them in an excel file. I divided .050 duration by adv. duration to arrive at an "intensity" factor. Nobody else is making cams with the same rates as Comp's XE lobes....nobody. However, Crower does have some interesting grinds with unique duration specs.

 

I was talking about getting a cam from comp grinded to the .050 duration of the zz9 cam. I was thinking about getting a 215/224 based on the 3108/3119 lobes bcuz they are just as aggresive as the XE lobes except they offer more lift. I would go with the 3100 XE lobes bcuz Bret said that those lobes eat up lifters from his experience. He told me that:

Cam schoool 201. You need to pick lobes you can run depending upon lift. Too much lift and you have a hard time with springs.

and:

SBC like more exhaust split. They like it alot more if you have less intake duration than you normally think too. It basically is there to keep the HP up there past HP peak.

 

So I forgot which one we are picking? Did we say the 224/236 had a little more torque? Also which one should I get if I plan on adding a supercharger down the line? I would rather not change cams twice. I called the Comp tech line and he just said "Yea the 224/230 is a big cam, it will work well with a blower." Not much info there.
But I do plan on passing emissions. ( I will take the blower off for that and tune it leaner) Now someone mentioned that the 218/230 has more overlap. What benefit does that offer? And I remember someone said it will pass emissions pretty easy. What kind of powerband does that cam have or better yet what kind of power will it put out with our setup.
I think I will read the whole topic over about 5 times and try to figure it out.


Tom

 

the 218/230 with a 112 LSA has 1 more degree of overlap than the 224/230 with a 114LSA...really a minimal difference. If both are on the same LSA then the 224/230 would obviously have more overlap.

The 218/230 is a popular blower grind. If you're really concerned about emissions go with this one on a 114 LSA.

 

Can I expect as much power out of the 218/230 as the 224/230? I do not want to sacrifice power. I know the 224/230 can pass emissions with tuning so it is not a big deal. But would the 218/230 need tuning to pass? Thanks guys.

 

If you think you can get the 224/230 to pass, go for it. The added duration will keep the valve nearer peak lift for longer as compared to the smaller 218 intake lobe.

The 218 would make almost as much power, you might be down 12-15 peak HP but the avg hp throughout the RPM range (which is what is really important) wouldn't be down that much. I just recommended it because it would be a safer bet in terms of emissions.

 

60, 65, 69, 75%... blah.

I'm curious though.
Those of you saying that lower than 69% is bad..... what exactly happens to power when you have an I/E ratio of let's say a really "low" 65%?

Curious as to the theory here.

-Mindgame

 

Very good post, guys. I appreciate that because I am due to install the XE 224/230 with ported LT4 heads very soon. Can't wait to see the results.

 

Hey guys I forgot to mention it earlier but we were talking about the head flow ratio's before. If you do the bigger valves through Lloyd you will get around 275/190 flow #'s. But if you stay with the stock valve size, which my cheap butt will have to do, you should be around 260/190. That is a better flow ratio right? The 275/190 is 69.1% while the 260/190 is 73.1%. So really that is better right?
Of course I realize the 275 will flow extra air into the combustion chamber. But maybe the 260 will have better velocity? We will have to post results because it willl be interesting to see.
I still have not decided which one to order. Right now it is between the 218/230 and the 224/230. I dont really understand the LSA yet but I will before I order.
One last question while I have some smart people listening, why would I want my exhaust open so much longer than my intake? To me it would seem that I would want the intake open longer to produce more velocity on the exhaust side. Combination Motorsports offers a comp cam like this. It is the 230/224. It has like .536"/.544" lift with 1.6 rockers. Please be gentle as you disprove my theory.
Tom

 

69.1% vs 73.1%

What is the difference going to be in engine performance?

Will the high rpm suffer because of the exhaust flow (lower ratio)? Haven't seen evidence of that. Just curious why some of you are set on the "higher is better" theory.

-Mindgame

 

Well I only really found one topic about the exhaust/intake flow ratio and it seems to agree with Mindgame. Not many details though. But this link also answers some other questions I had.
Check it out:
http://www.hughesengines.com/www/hug...s/head_faq.asp

What does he mean that it has importance but not at maximum lift? It would seem to me that it would be most important there. Isn't the ratio going to be constant all the way through the rpm range?

Tom

 

Cool link:

http://hotrodders.com/kb/engine/calculators.html

I was wondering on the calculator for torque to hp do I use the rpm at max torque or at max engine rpm? Big difference. My car had 329 RWTQ at 3800. The engine redlines at the stock 5600. It had a peak RWHP of 255.
Now either formula I use does not come out right I think. 3800 rpms comes up with 238 hp. 5600 rpms comes up with 350 hp. I would like to believe that is the right answer but I do not think so.

 

here is something about cylinder head flow:http://www.gmrc.org/gmrc/techpaperspdf/AirFlow.pdf

Don't know if it will help.