I've narrowed it down to this for my street driven weekend warrior:

-350 sbc bored .030 over
-world sportman II cast iron heads with 64cc chambers ported out to about 68cc
-11:1 flattop pistons
-.041 head gasket
-comp cams 280 duration
-shorty headers
-mechanical secondary carb (not sure which one yet)
-3.73 gears and rebuilt 700r tranny
-150 shot from the bottle

Please criticise me!!!!

 

Sounds like low 13's on motor and high 11's on spray. Put a pressure guage on the bottle and torch it to 900psi. Hope you're using radials. Have fun.

 

close but no 327 without nos

 

Yeah, sounds quick and its being built right now! I haven't decided on an intake just yet, and I am still open to criticism. It'll probably be in the car in about a month. Luckily I have plenty of help.

 

I'm not running nos, its an NX plate system and I have jets for up to 200 shot.

Where are you located? Maybe we'll meet sometime?

 

i live in arizona. 10.20 no nos or forced induction

 

ok systalis, you should check out this l84327 guys other posts, he's on crack. I would be vary wary of listening to his advice. I think I can hear therckid screaming...


might want to edit your first post with your newly found info, ie, 10.2-10.4 CR. Flat tops don't equal 11:1 usually.

flat tops (got a part number?), decked block, and 68cc chambers will net you ~9.8:1 CR, or thereabouts. Seriously, get all the numbers and run 'em yourself. you WILL feel better having ALL the specs you can on this motor. Keep it in a binder, tucked away, for *when* you inevitably want to change something. A lot of engine builders will round, and guess here and there, usually you can get away with it (this guys done it before eh?), but it's really nice to know **exactly** what you have. You can better optimize your combo, and squeeze that last 20HP out of it.

Generally a split pattern cam makes more power. Generally. The comp280h is not bad, but i'd ask him "hey, some guy suggested a split pattern cam, any thoughts?" and see what he says. I don't know the flow #'s on those heads, so who knows, maybe they work well with a single pattern. I think nitrous usually likes more exhaust duration as well (another reason to go to a dual pattern). Or for that matter, use 1.5 rockers on intake, 1.6 rockers on exhaust.

If you ask him why that cam, and he says:
"well, I got a few on the shelf, and it's thereabouts what you want...." I'd suggest otherwise...
if he says:
"because the heads flow xxx @ yyy, therefore it'll run the best". Then you're sold.
weekend warrior? 350 cid? I'd be thinking in the mid 230's duration @.050" intake, higher 230*'s exhaust. Like the compxe274. I think the one step larger might work ok. Make sure the convertor is matched to it as well.



oh, one last note, is the block being decked? if not your CR will be considerably lower. here is what I have, for comparisions sake (see attachment).
I used United Engine and Machine Co.

 

sonix a quick question to you. i'm building up my engine right now and have got it all my components ready , thanks mainly to the replies i had off you beginning of the year,. having read this one question sprang to mind . systalis mentions running a 11 . 1 CR on cast heads ? i was always told that thats way to high and at the that CR you really should be running ally heads ? what are your thoughts on this. I ran the comp test page you linked to and it put me at about 10.5 . 1 , i've decided on ally heads but would i get away with cast,.

p.s sorry for the hijack but it is sort off related

 

Thanks again sonix. I would never listen to any of l84327's advice. He's like all of the kids down here. He can't give any engine specs except horsepower and quartermile times. Everyone in my town has a 10 second quarter mile street car........until they run 15's at the track. I would just like to race this "10 second" 327 in a month or so when I'm dialed in.

Your point about cams is well taken. I will ask him about the split ppattern cam.

 

yea, 11:1 on iron heads is too high. AL is ok, if you have a decent sized cam (bigger bleeds off more pressure), and a good cooling system.
10.5:1 is kinda borderline. FWIW, I run 10:1, which as some experienced people will tell you is also pretty borderline on iron heads, with a "normal" sized cam. My trick? 4000' altitude and 91 octane gas. I forgot once and put in 87 octane from one of those cheeep places. It ran REALLY weird until I realized what I did...
I'd go with the AL heads in your case, if you can swing the cash. You have the option of porting out your combustion chamber on cast heads though, or bringing it down to 10:1 or so. Use that link I posted for the CR calc, but do the dynamic CR. You'll need your intake closing angle, they say to use it @.050 and add 15*, but if you have the actual closing angle, I use that, it's more accurate usually. Keep that below 8.5:1.

 

I don't know much about cams but I have used that calculator many times before to calculate static on that racing engine that I was trying to street. I ended up selling it for parts.

What would be the intake closing angle on a comp 280h? or how about a good split pattern cam?

 

look it up on comps website, I know the info is there, I just found it on my xe268h. I would for ya, but i'm kinda busy building my motor right now...

 

Thanks, will do!

Did it...

With a .040 head gasket and a 2cc piston volume with 5.7'' rod length and comp 280h it gives me 10.228 static and 8.091 dynamic. Should be ok?

 

even if this engine existed his would still have more power making potential due to the fact that it has more cubes. Why waste your time posting such a worthless reply that has no bearing on the question he asked and is most likely utter bs? Jeeze now you got me wasting space in this post..

 

????

 

What about my combo with these heads? (I goofed...see next post)

 

sorry about that

eBay Motors: 340292 S.B. Chevy angle plug heads, 2.02 1.60 (item 200017274798 end time Aug-20-06 19:00:00 PDT)

 

ah, 292 heads.
Not too sure about those heads.

as to answer your previous question - i'd double check the 2cc piston volume, where'd you get that spec? Never heard of a 2cc piston.
10.2 and 8.0 is ok, should run alright. Needs 91+ octane, and be gentle with the timing curve. Those are old school heads, so you'll need full timing for full power.
Just keep good gas in it and you should be ok.

 

sorry, I think i meant 5cc. (thats the valve reliefs right?) And I have a set of world sportsman II heads also that I am selling because i think that they have been shaved to 56cc. But if they are 64cc would they be better than the 292's?

 

yes 5cc sounds right.
IMHO yes, if the sports mans are 64cc, or can be opened up to ~64cc, i'd use those instead of those 292's. But since you've already won the auction....

 

I just got the 292's in today and they have had porting and polishing done to the intake and exhaust but not to the actual combustion chambers. This should make them flow much better right?

 

yep. do you have a die grinder? If I was you i'd sand and polish the combustion chambers.

are they in the condition they were in in the picture? I'd say a hot tanking as well then. I'm guessing you're using new springs, valve seals, etc etc?

 

Yeah, pretty much like the picture except you can't see the port work in the picture. The intake and exhaust ports are really smooth with no sharp edges and they are well rounded. I do have a die grinder and a carbide tip and I am planning to do the bowls. The springs look like they are pretty good but I'm gonna show them to the guy doing my build and see what he thinks. It will be hot tanked and cleaned up a little and prolly painted because my car looks too nice to put something dirty into my engine bay!!

I'm looking to make about 425 hp at the crank. I hope they are up to the task!

Thanks sonix, you always answer my posts with good sensable answers.

 

well if it's been ported, then the bowls might ok to leave.
I'd grab a few sanding drums and a mandrel, and just sand the chambers lightly. Maybe open back the wall between intake valve and spark plug, and smooth the spark plug boss on the intake valve side. Then use a few cross buffs and some WD-40 and smooth it right up, and if you're feeling really adventurous, throw on a felt bob and some metal polish and go over it with that too. Polish the valves too.

 

Is the metal polish just for kicks or does it really help the chamber? Do you think with the right streetable cam and full exhaust with a cold air intake that they would be the weak link in trying to build a 425 hp powerplant?

 

no, the more "shiny" you can make the chamber, the more it'll reflect it's heat back into the combustion process, and make more power, resist detonation, etc etc.

I don't think you'll get 425HP with a 'streetable' cam but that depends on your definition.

I'm not wise with those heads, so i'm not sure if it's the weak link. I wouldn't say "weak link" would be the difference between 375hp and 425HP for example.... "weak link" is like "bottle neck", or the reason your engine might be making 320HP say... But getting to 425HP it's not really a weak link issue, it's more of "what else can I throw in there to grab those last few ponies".
anyway, that's just symantecs I guess...

dual exhaust? I think if you can i'd go for that.
CAI - carbed? you doing a cowl induction hood or like a dual snorkle thing?

 

Its going to be carbed and i'm trying to get it all under the stock hood for "sleeper" reasons.

The CAI will be a custom job probably based on the dual snorkel setup but with better, higher flowing ducting possibly into a ram air scoop that opens up either under the front ground fx or possibly where the park lights are. I know this will tread on the legality issue, but hey, the car is only driven on the weekends and I can disconnect it and put the open element back in for inspection time. The cops aren't too strict around this area and I could prolly get away with it.

Should work huh?

Btw, the compression will probably be somewhere in the 10:1 or slightly under range and I think he suggested the comp 280 cam, but I did take Your advice and ask him about a dual rate cam and he's running it all on a computer program and se what gets the best #'s. He swears we'll be around 400 crank hp. I hope so!!!!