Iron block all the way, considering the cost difference unless it's an application where you are already getting all the hp there is out of it and the ~90lbs will make a difference that you can't (more cheaply) make up in any other way. IOW, an aluminum block is cool, but not cost efective except for a very extreme combo. Of course, if you already HAVE an Al block (a la LSx) then you are golden! But ~$2,000 to save 90lbs just exceeds even my desire to spend money on a car. Also, iron block may make a few more hp due to retaining the heat in the cylinders better. Or so I've heard. MG: any opinion on this?

I like the LS1 block and heads for an NA street car unless you really want to go mega-buck all-out ***** to the wall. In that case, gen I iron block with killer heads. Not knocking the LT1, just where I'd go with a clean slate.

Rich Krause

 

Nice...

but my question is:

you state AFR... afr heads for the LT1 are basically SBC heads with the necessary holes for teh retro-cooling as far as I am concerned, so they are not 15º heads which are your personal favorite (as it would be mine and I can surely understand).

Factory LS heads are being ported very very big in CCs... so... they are not a bad choice and they are already 15º heads. But I see your point clearly...

My main interest was more CID for more power on pump gas.. that was what I was after and really on the LT1 block is either 383 or 396, not much more to it "reliably" or comfortably. Having a 7L with a good rod/stroke ration might make it live a little longer on the charger.. The better the heads the less you rely in the supercharger and the better the power on Pump gas or at least that was what richard krause taught me hence I followed his advice and upgraded my heads...

My personal "magic" goal would be a 7L (which ever best combo for the $) YSi-trim supercharger on pump gas getting max power.

Mindgame on that link jegs has the motown aluminum lite block for 3500... nice... interesting.. hmm..

 

I've read the same thing Rich. Aluminum supposedly takes a small hit in thermal efficiency, so there's probably a little bit of power lost there as you stated. Possible to recover some of that loss in using higher coolant temps? Just a thought but I'm not real sure. Just one of those things most racers will accept for a bit of weight loss. Kinda like the loss in thermal efficiency of an aluminum head vs cast iron. Of course the high side is the weight loss and more compression/better octane tolerance.
One other thing worth mentioning about aluminum blocks is, (actually the same applies to heads) they're easily repaired should you window the block. That's a nice thing to know considering the cost.

Highlander, I only mention AFR because they do sell a CNC ported 18º GM cylinder head.
Not to mention, their 215cc RR head is a stout one in its own right as is the 227. On a 427ci small block, I could see a ported 227 making 650-700 hp on pump gas. It'd need to turn some revs but I've seen a Dart 220 RR head go close to 700hp at near 7k rpm in a 434. Really stout cam in that one though..... but I'm sure it could be street driven. Maybe a good weekend driver.
The race heads (non 23º) will do that with a much smaller cam.

And there are better heads than the 15 and 18º GM. GM SB2.2 and Brodix canted valve come to mind.
It's just that the 18 and 15º stuff is more plentiful and requires less specialty stuff to do the job.

Good luck with your goal.

-Mindgame

 

canted valve heads ona a big SBC =

 

Correct me if I'm wrong, but if you bore the LT1 block out far enough for a 4.2"+OD sleeve wouldn't you be completely into water? I'm almost sure you would, which means using a single conjoined sleeve per bank. To my knowledge, Darton is the only one selling that part, which is only (to my knowledge) made for the LS1. Is the deck height and bore space the same between the two? Even if it is, those Dartons are $$$$. Just the sleeves cost about $1,300 and you don't just hack down the block with a regular boring bar. They are done with a special bar that few shops have. I don't think there's even one in KC, and Darton charges $1000 to install them.

All that gets you a crappy LT1 block that still has the Opti. For that kind of money you should get a crank trigger, a Dart block, and build a 454" smallblock that you can really lean on without worrying about GM's lousy LT1 castings. If you're stuck on using a GM ecm, get a modified sy/ty box and build the harness. It's really not difficult to build those things if you have a good wiring schematic and some basic knowledge.

 

Oh, and for the record, SB2.2>>>>>>LS1. Do you realize the kind of power a 427" SB2.2 motor with pump gas compression and a streetable hydraulic roller would make?

 

Price????

It looks a lot more expensive than a 7L LSx

but SBC 2.2 heads are way big in CCs.. Doesn't that hurt street driving at all???

I believe that 300+cc intake ports, even on a 7L, is still too much for the street.

My question is.. for some reason GM used the LSx instead of the SBC 2.2 for their ultimate street power machine... Remember that my goal is always a street car on pump gas...

Please feel free to correct me... im here to learn.

 

I just realized that an SB2 can't run hydraulic lifters

 

why not?

 

Adio,

Because of the lifter offset. Firstly, you won't find a hydraulic lifter with the correct offset. Secondly, if they made one it probably wouldn't survive long with the loading off center. Not to mention, guys running these heads are putting a bit of spring on them to take advantage of the airflow. Counterproductive all the way round.
The same thing holds true for most of the "race" heads with valve offsets, including my 15º heads.

Highlander,
The SB2 and SB2.2 (different heads by the way) come from the foundry at ~195 ccs, so they can be ported to any size you could want. Most porters are offering them in anything from 280 cc on up and flowing 380 cfm or better.
If Chuck Riddeck still posted here he could tell you the details on his ride. 434 ci, SB2.2 heads, and the thing makes well over 700 hp at the flywheel. I drove this car when I was in Texas here last year and it is very streetable! The cam as I remember is in the 250@ .050 range and that engine gets it all done by 7k rpm. It's a monster of a street engine in every apsect. I have yet to see a LSx big-bore do that but that doesn't mean it can't be done. This isn't a superiority contest.... it's a matter of cost and the SB build wins all day long.
Price these heads used sometime. I sold a set here a few months ago.... professionally CNC ported by Don Losito of Ultra Pro Machining. No slouch and considered to be one of the best cylinder head guys out there. Had a little more than $4500 in them and ended up letting them go for a bit better than 2k. That hurts, but those deals (and better) are not uncommon FWIW.

-Mindgame

 

Well.. that was my "main" concern... cost vs power... and I htought the lsx was a better choice... i guess its otherwise as you have noted... i will read a bit more on it... I have a bad thing in my hands maybe you can help me with

http://web.camaross.com/forums/showt...34#post2172834