Another $$$$ to performance.
This is a discussion on Another $$$$ to performance. within the Internal Engine forums, part of the LSx Technical Help Section category; Sounds like someone got upset because a few of us don't like these little motor/big head combinations. I'm not aware ...
01-08-2011, 02:39 PM #81
Sounds like someone got upset because a few of us don't like these little motor/big head combinations.
I'm not aware of anyone here saying this combination just doesn't work. That's certainly not what I implied at all here.
I'm simply pointing out the fact that these setups are a bit weak on the torque output and peak rather high.
Lets take the only 3 dynos posted in this thread on the previous page for instance.
A) Uses a 223/231 cam,,,ya a bit tame from my view point,,,it's also ground at a 113 lsa with 4 degrees of advance ground in,,,but no mention of where the cam was installed at, but I'll leave that alone and try not to get into all the cam specifics for now.
It made 460 hp at about 6,000 rpm. The HP peaked somewhat low, could be due to alot of things, duration being small is one, or possibly this cam is installed with more advance adding to what is ground in bringing the HP peak rpm down a tad?? We'll never know for sure.
What bothers me as I've commented on already, is the peak torque and the rpm it occurs. 446 tq at 4700 rpms. Not to mention it's not very flat either.
This is a scenerio that I mentioned earlier I prefer to stay away from in a street car. Only 1,300 rpms between peak torque and peak horsepower. To extract optimum ET's from this combo would require a pretty stiff rearend gear and a very loose torque converter. Eh,,,,doesn't get me excited.
B) Now lets look at this one. 370 cubes with a cam claimed to be 242/250 at .050. LSA is 114 also with 4 degrees of advance ground in. No mention of where it's installed however.
Still we have peak horsepower of 490 occuring at 6600 rpms. That's great, but again look at the peak torque.
437 TQ at a whopping 5,300 rpms. That's only 1300 rpms between the peaks,,,,,again. I'm seeing a similar occurance here with 2 completely different camshafts Could it be these smaller engines just don't need that much head to fill the cylinders??? Lets look at dyno #3
C) This guy seems to want to be secretive on his cam specs and only tells us the duration is mid 230's and low 240's. No mention of advance or where the cam is installed.
He made 508 hp at about 62-6300 rpms, a very early peak for that number. Could there be alot of advance in this camshaft?? Maybe he was trying to pickup some torque with this grind?? We can only guess.
He made 441 torque at a peak of what appears to be about 5,300 rpms.
Now we are talking a spread of roughly 1,000 rpms between the two. Wow, talk about your steep rear gear.
What I find interesting from this guy, he states the same thing I've already been saying earlier.
He is unhappy with the low end and was hoping for more. Then comments how hard the heads come on up top. Imagine that, large ports on a little motor. Then he says,,,,"The heads made great power up top but the large ports sacrafice low end torque". This is right from the horses mouth.
This is exactly what I've been saying here. I never mentioned this was a bad combination,,,,,it just lacks a fair amount of low end torque with very peaky numbers that aren't very forgiving when it comes to the spread from peak to peak.
This isn't necessarily a bad thing, never said it was. But for those of us looking for optimum ET's without sacraficing too much in the form of street manors this combo isn't the best solution. It requires alot of rear gear, very loose converters, and would work better in a lighter weight car.
Some of us (me included) prefer to make more low end grunt at an earlier rpm range. Makes for a fun street car that doesn't require as much rear gear. I would much rather prefer to see these L92 heads on a larger cubed motor (400+) Something that actually needs the larger head to fill those cylinders.
The L92's on the little 364 (and even the 370 in one example) just isn't my bag.
Last edited by Firebirdjones; 01-08-2011 at 02:44 PM.
01-08-2011, 03:04 PM #82
I picked up a set of used 5.3 heads today for 200$ 862 Measured out the cc's when I got em home. Intake runner 195cc, combustion chamber 58cc Thats just what I got. Also there flat, and look pretty good. So I think I'm going to skip the machine shop on this one, and just use lapping compound on the valves. Because I wasn't planning on doing something like this right now, I am going to have to pinch every penny, then squeeze the penny when I get done pinching it.
Either way. I was pretty impressed. Valve springs will be in the mail Monday. It will be a couple months till I get the short block done. I'll update ya'all on it then...
planning on just a mild clean/smooth on intake and just polish on exaust. Port match match both too. I'll just be at 369ci and no more than hmmm 6500. I don't see a need for big heads on THIS ENGINE.
So I guess I've decided to roll with an LS, I have a few other things to finish first though. Always seem to be getting in over my head, instead of picking one I picked both. To bad I can't do that with women! not quite sure what it's going in, but It will just get parts as I come across them.
Last edited by Jay37; 01-08-2011 at 07:05 PM.RUDE, CRUDE, AND SOCIABLY UNACCEPTABLE.
01-08-2011, 03:19 PM #83
Ok firebird, I have a question for you.
With my GTO weighing 3665 with me in it, 408 stroker, fully forged bottom end, Edelbrock proflow intake and Trickflow 238/242 .595/.595 112lsa cam and (right now with my milled 241s) 11:1 comperssion, 4,000 rpm stall and stock 346 rear gears. I'm willing to spin it past 8,000rpms, but don't really want to go with a larger stall than the 4,000 I have.
What heads would you recomend for all out power on 93 octane pump gas with this cam...and if not, what kind of cam specs would you recomend? (In the near future this will be my weekend toy) I not only don't mind "bitchy", but even kind of like it. I'm looking for a down right nasty setup with the prospects of even adding a 250-300 shot of n2o.
Then I'll be changing my setup years and years down the road (lol after kids are out of the house) to a full blown twin turbo setup, but I'll dea" with that when I can save up several thousand for it.
01-08-2011, 04:01 PM #84
- Join Date
- Jan 2011
- 2002 firebird
The problem is most of these guys choose max effort camshafts or setups or cams and combinations that are great for dynos vs combinations that make the best avg power...... We have seen guys lose their minds because after they built a combination and the combination did not produce the desired horsepower or peak numbers, throw more money at the combination for a dyno.... ie horsepower chasing and dyno racing....
Regardless of if you went with a cathedral or square its all about where you want to make your power and your intent, and unfortunately, the interweb dyno sections are full of guys that are only interested in sexy HP #'s and want to try to reach the highest number possible... and these sponsors or venders promote this to sell products......It has trickled down to the consumers and avg joe.....
reagrdless physics is physics but then comes the displacement rules and whether you put a square port or cathedral port on more displacement, the rules will change ie more torque... Lets remove Horsepower from the conversation because the goal is to make torque in the grand scheme of things..... I know horsepower gets thrown around so much..... But a 3.622 crank in correlation to 3.9 - 4.0-4.065 cylinder will only hold a certain amount of air volume...period..... So the trick is to manipulate camshaft timing events to correlate with the users goals....... As you increase cylinder volume and crank, you increase torque.....
So the concern with higher torque peak values are systematic to SBC and crank and cylinder size ie displacement.... So yes more displacement will make more torque, easier, and earlier...
The LSX are making leaps and bounds over gen I and II's due to cylinder head efficiency....... Never did they have gen I or II's making this kind of power with the same displacement without pushing the limits of sanity almost and more cam and more head..... Now its main stream because for years you have been pounded with the small port=velocity propaganda, and that works for gen I or gen II's but some old school guys who knew what they were doing back then would use larger ports and get decent power but it was taboo and not status quo and against conventional theory..... The key here is understanding camshaft timing events and understanding the functionality of what you have in a perspective of the complete combination....... You have to know when to open the door and when to close it in simplistic terms...
01-09-2011, 07:02 AM #85
I agree, the dyno has become more of an icon than a tuning tool. Alot of chest pounders out there fixed on a HP number without looking at the whole package. I have to believe the wonderfull world of the internet is somewhat to blame.
Nobody (on the internet anyway) pays any attention to BSFC's anymore, a direct relation to how efficient the engine is at making power.
Peak HP sells and that's just the reality of marketing I guess.
01-09-2011, 07:06 AM #86
01-09-2011, 08:47 AM #87
I love the intake and its capabilities, I think I can also get it for the l92 heads...its a third of the price of the FAST intake and out performs it, it just too tall to fit under the hood (or cowl of an F-body) without doing some cutting
01-09-2011, 08:40 PM #88
01-10-2011, 06:36 AM #89
01-10-2011, 06:18 PM #90
01-10-2011, 06:25 PM #91
Also I've decided to run factory, crank rods. and just get the block punched. If I want to be cheap I can't be picky. It's against my morals, But If I want to get a good feel for this I need to be thrifty. Also I think I'm going to get .060 over pistons. Can't seem to find a set of hypers for less then 400-500. Even the replacement casts seem spendy. Any Part#'s I'm missing? I'd like to be able to get a master rebiuld for 600 w/hypers Is that doable? That would really help costs.
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