this the intake on my build.added a 1" carb spacer to improve hi rpm . I supposed it should work but possibly a true single plane and some porting can make the difference...

TSW, please simulate my engine both with a dual plane and a single plane...and suitable carburetors



[/QUOTE]

 

63mako, so there's a PV also in the secondary? I blocked it when I put my hands on that carb. read something here and there and there was not a sure word about...

love the tuning job that has been done on my motor, the staggered jetting above all. My jetting was 2 numbers higher.

it has been pointed out that the nicest thing is the broad torque curve. OK , now i understand why I've been never really concerned about the streetability of this engine...
my previous engine is same as this but with lot of problems and lack of tuning, but I loved it and now I understand why.
the power-torque in my usable range (2000-6000rpm ) is released in a "natural" way , can't explain otherwise.very nice throttle response, progressive but fast acceleration

 

63mako, thanks for the info, so if i read this right, LEAN IS HOT, so richen it up to lower the exhaust manifold temp. My 569 intake has the divider to within a fraction of the top, what if i put a 1/4inch open insulator gasket ? Will that eliminate the difference in the high and low intake cylinders? I read on another board that gm recomended the following
lp 78, rp74
ls80, rs 82
I noticed yours had the right rear as the leanest
what about square jetting the carb and stagger jetting together

Any body have expeirence with the 569 intake that came on the 70 ls6 chevelles and 71 ls6 vettes??

 

With certain older manifolds fuel separation was a big problem. It was caused by to short of a distance from the carb base to where the fuel has to make a 90 degree turn heaeding to the cylinders. The fuel being heavier can't make the high speed 90 degree turn.

That is where carb spacers come in. From what I have seen there is no one magic carb spacer. every motor combo needs it's own. But generally 4 hole designs seem to work the bests to give the bigger drops of fuel more time to atomize before crashing into the bottom of the plenum in single plane apps. An open spacer opens up more side to side flow in a dual plane without milling the divider away.

I'm pro thermal spacers.

Does that carb have 1-1 linkage to run two PV's?

 

The C-454 intake rocks!!

BTW- remember that those specs GM listed for stagger jetting usually involved the Holley's with the mixture distribution tabs and opened plenum. What they did here with the regular 800 Holley is going to be different than one with the tabs and an open plenum.


JIM

 

You have PM. Everything should be there to plug this in. If not let me know.

 

Yes, I've more questions, so you have mail...

Aldo, it may be a couple of days before I can post up results, but I will definitely check a few larger cfm carb models while I'm at it.

 

I sent you everything but the cam duration @ .200. Don't have anything else on the cam except the info on the cam card i sent.

 

Comp gave me the @ .200" info today so I can finish fine tuning the profile this evening, which will give me a better picture before I firm up the initial conclusions I've made so far (PM'ing those to Kevin). FWIW, what I'm seeing so far looks to indicate in the neighborhood of as much as ~80 HP missing, with a handful of suspects. Stay tuned...





edit - ...keeping in mind the old computer adage "garbage in, garbage out", of course.

 

A/F ratio is good all the way though the pulls, slightly richer up top 12.5. Timing is rock solid from 3000 to end of pull. Engine runs so well I don't think it is possible to pull any more power out of it. We adjusted everything numerous times, valves looser and tighter, changed springs, 3 different distributors, 3 different carbs, 18 tuning pulls. It is what it is. The dyno could be off but I don't think that much. It is off the dyno, crated and ready to ship. I really a lot of it is the intake The 427/425 had this intake, 11 to 1 compression and a little smaller but better match to 11 to 1 solid lifter cam. Shows peak HP @ 5800 RPM.

 

my reference L88 build in past months has been this

http://www.superchevy.com/technical/...tor/index.html

my same dual plane intake, 850 DP carb , same heads...

http://www.superchevy.com/technical/...nce_parts.html

same CID , same cam lift but different, unknown duration...but 12.5:1 CR and race gas of course. look at dyno graph...

http://www.superchevy.com/technical/...arburetor.html

I leave to experts the thoughts about...

Kevin , happy anyway.what matters now is to have my car back on the street

 

Elle88.....you need to read this sentence from the article and take it VERY seriously!

NHRA Stock Eliminator - Ain't Nothin' Stock About Stock Eliminator

Stock Eliminator racing is absolutely some of the fiercest competition on the NHRA circuit. Folks who build and race those things don't do an article in Super Chevy and divulge all their secrets...not even close. That engine went on to set the world record and the MPH he was turning strongly suggests insane RPM and at least the HP indicated.

There are several areas different than yours.

First the pistons and ring pack. Not as much about compression (but definitely helps!) as it is about the rings. They will be using VERY low tension rings with napier 2nds etc etc. I can tell you that rings alone for these motors can often reach $900-$1500 plus! There can easily be 30-40 HP in ring setup alone. Not good street stuff...but great for racing. The domes will be made from molds of the chamber to fit perfectly. Nothing universal. Same level of parts as NASCAR. The rings are sealed in bags and you use gloves to handle them to keep *microrusting* from happening from the oils on your fingers!

Cam- That cam is from Bullet. Bullet is very well know for killer *Stocker* cams. Their designs originated from Harold Brookshire who owned Ultradyne cams and sold out to Bullet. Harold also designed the original Comp Hi Energy cams (268H) and the current Voodoo series of Lunati's. Does lots of NASCAR and other race stuff. Ultradyne was famous for very aggressive and fast cams for class racers. But don't even begin to confuse a cam like that for something that will last even a 1000 miles on the street. The lift is the only thing they check...everything else is wide open. It will *check* good at the required lift points...but everything in between will be dramatically different. Those cams only run for 20 seconds at a time and are torn down regularly. Did you notice their peak HP came in at 6500 RPM and Peak TQ was in the 5100 range? Where was yours? RPM is where big HP comes from and those engines are going to live in the 7500-8000 rpm range at least. There's 50-75 HP here at least.

Heads- yes they are same castings...but the amount of time put into the valve job is incredible. They will possibly/likely have 50* or steeper valve angles that last one or two weekends. They may have a different valve job on every cylinder to maximize flow. My own heads have two very distinctly different valvejobs to account for the *good and bad* ports of the BBC heads. There were stacks of valves tested with varying backcuts etc. They will use different valve shapes...tulip, nailhead, backcuts etc. Trim down/reshape the chamber side of the valve head margin to reduce reversion and increase inlet flow.There is big power in those heads...nothing like stock. Another 50 HP at least...and the ability to *hang on* after peak HP and scream to the finish line.

The headers for one of these will be very scienced out and exactly matched to the cam and heads and intake flow with respect to exhaust speed.

You will also find incredible time trying to *free up* HP. Cam tunnels line bored, every single thing that turns or moves is made perfect by machine work. They can't use a lot of trick parts, so there will be many, many thousands of $$ spent on machine work to make it all work at it's best. You will find them honed with hot water flowing through them, oil shedding coatings, thermal coatings, heads moved around on the deck to unshroud the valves, cylinders moved around to unshroud valves, very loose clearances, hours spent sorting through heads and intakes to find the best ones. Just fitting the intake to the heads can take hours. I know some guys with a winning 428SCJ Ford that you wouldn't believe what they have to do to get that great big intake perfect without touching the ports!

5-30w or even thinner race oil. More power.

The point of all of this is you are looking at a state of the art race motor....nothing even close to what GM or the race teams assembled and competed with back in the day. These things have come a long way and to buy one of these is HUGE $$$. Your entire investment in your motor wouldn't touch the heads on a winning Stock Eliminator motor...much less the rest of the build. It's that crazy. Super Chevy runs an article like that and makes it look easy in a few columns and pics. And again...the folks who build them aren't giving away their secrets for sure!

You'll have fun with your street friendly L-88 for sure!!

JIM

 

Here are some actual ZL-1 dyno results. 12.5 to 1 comp, Open plenum, Bigger carb.
http://www.camaros.org/copo.shtml
http://members.***.net/harddrivin1le/ZL1DYNOTEST.JPG
Stock L88 dyno was 430 HP @ 5200 RPM with manifolds and 12.5 to 1. We hit 460 HP @ 5200 with headers and 11 to 1

 

63mako & 427hotrod, what a surprise the infos posted!
why didn't posted them earlier? I would have saved a lot of headache!

63mako, yes our build is more than right considering this dyno:
http://members.***.net/harddrivin1le/ZL1DYNOTEST.JPG

sorry for my doubts

427hotrod.I would never suspect all that amount of job on such engine as you described. yes the Superchevy article is really misleading, at least...

 

If you look at the dyno sheet there is a spike in power above 6600 after it looks like you hit peak power and it drops a little. We never ran past 6600 for the same reason they quit their dyno testing. We didn't want to put the motor at risk. It is your prized posession not mine. Lots of things can happen @ 7000 RPM and up on a dyno that subjects the engine to more stresses than it will ever see in the car. What is real interesting is the real ZL1 and our build have almost identical peak power and torque numbers when set up the same on the dyno but if you look at the power @ 5000 to 5500 our build has it beat by a good margin with a noticably flatter torque curve. @ 5250 where HP and torque intesect we are at 465. The ZL1 is at around 400 Way more upper midrange due to the differences in compression, heads, intake and modern lobe design on the ZL1 nostalgia cam.

 

yes 63mako

i traced the graphs of our build and they look like those of the ZL1 above

just a quick comparison :

ZL1 : 508 hp , 470 lbs/ft , headers, 850cfm, single plane intake, 12:1 CR, 103oct gas
mine: 503 hp , 466 lbs/ft, headers, 800 cfm, dual plane intake , 11:1 CR , 98 oct gas

so we are there.
OK not the beast I expected but...I remember when at the beginning of this build everybody saying : go solid roller! but it needed to be an old school engine build

Aldo

 

First and foremost, I don’t want to leave it unsaid that as much as to possibly help Aldo in considering optional carb/intake combinations, I ran these for my own entertainment, and not to second-guess Kevin’s work. He’s been around the block enough times to have a good handle on what he’s doing without my coaching, and I value his opinions on this stuff as much as I like to think he values mine. And, despite the fact that this material must be taken with a large grain of salt, as should all simulations, I’m just sharing in hopes some of this is worth throwing in the hat for future reference to someone, not to parade myself as any sort of guru, whatsoever.

Suffice it to say there wasn’t nearly the “missing” HP as might have first appeared before I got everything entered and crunched, as it’s not my intention use my findings to belabor such, please don’t get hung up on the fact that I haven’t posted all of the numbers. No, what is much more relative here are the differences made by changes from the baseline. In addition to apparent differences between the actual dyno and the software’s calculations, since I may also have been overly generous in my estimations of the existing intake’s flow coefficient and the exhaust system’s CFM, there is plenty of room for error. With that qualification, proceed at your own caution in consideration of this overview, such as it is…


The existing intake with 800 CFM carb looks to be nearly maxed out on this build - with max CFM reaching 789 and peak intake vacuum sucking hard at 1.9 “Hg @ 7000 - and verses other optional combinations is almost certainly holding this engine back somewhat from its true potential. How much???

Put an 850 CFM carb on the existing intake, and that’s worth ~5 HP and ~5 ft.lb. Max CFM hits 795 with a little more margin left, and peak intake vacuum improves to 1.7 “Hg @ 7000. No drop in idle vacuum from that projected at 6.8 “Hg.

Moving up to an AirGap & 850 CFM carb looks to be worth ~25 HP and ~20 ft.lb. verses the existing intake/carb setup, with idle vacuum dropping only slightly to 6.6 “Hg. Max CFM of 824 and peak intake vacuum of 2.0 “Hg @ 7000 would indicate this is still possibly too little carburetor capacity on top end, given the better intake which is responsible for the peak intake vacuum having gone up despite the larger carb.

Change up to a 950 CFM carb on the AirGap and there’s another ~15 HP and ~10 ft.lb. over the AirGap w/850, or ~40 HP and ~30 ft.lb. verses the existing setup, with no further appreciable drop in idle vacuum. Max CFM reaches 840 (the 950 yielding plenty of room to spare), but perhaps more importantly peak intake vacuum falls to 1.6 “Hg @ 7000, and idle vacuum holding at 6.6 "Hg, indications are the engine will likely be happier with a larger carb than even the 850 on a premium intake.

Swap for a Victor under that 950, and there could be as much as another ~30 HP and ~20 ft.lb. or more available, or ~70 HP and ~50 ft.lb. verses the existing intake/carb setup. Max CFM hits 864 and peak intake vacuum sits pretty at 1.5 “Hg @ 7000. Bear in mind that manners may suffer, as this is the one setup out of the group which had significantly poorer A/F mix quality at idle, despite idle vacuum holding at 6.6 “Hg.

Lastly, just for kicks and grins I couldn’t resist plopping a model C-454/1050 combo on it before I was done, and its projected HP landed right between the AirGap w/850 and AirGap w/950, but holds on better to and beyond 7000 rpm than either. Breathing easy with only 1.3 “Hg @ 7000, surprisingly the idle vacuum also projects to be better than any of these other setups, as well. The A/F mix quality isn’t anything to brag about, but it’s worth noting I haven't made compensations to the program to account for the Dom’s superior metering. This, together with past experience, is exactly the kind of thing giving me so much trouble firming up any decision against going back to a Dominator style carb on my current 427 makeover.


Bottom Line: It should be no far reach to conclude that a quality intake and sufficient carburetor are vital to getting the most out of a particular build (whatever that means to you), and the above would seem to bear that logic out. Waste of time? No, whether it's worth anything to anyone or not, I needed the practice anyway...

 

TSW. Thank you for your time, effort and the PM help designing this build. You were a big help. This confirmes my thought that the intake is a limiting factor here. An increase in the high rpm cylinder pressure either by going with a smaller cam or increasing compression would also help with power output even with this induction setup. I knew that up front but piston selection is very limited in a 427 .070 overbore and cam selection was already determined. Your results confirm our actual dyno results that a bigger carb combined with this intake was not worth much additional power. That said this setup as is will give Aldo great upper midrange, pull to 6500 RPM, still fit under the hood and easily run on pump fuel. There is a lot to be gained in a street driven car, durability and detonation resistance keeping the peak cylinder pressure at a safer level as well as this carb starting to go a touch richer up top and a little leaner at idle due to it's size and the vacuum at idle. Improved idle quality was an unforseen bonus. Compromise is the key to a great street engine. Max peak HP is the goal on any race engine but there are other considerations that are often overlooked in a street build in the quest for maximum power.

 

I'm sorry I didn't go read the articles closer that you had mentioned a few times. You're right...it might have saved you some sleepless nights! But unless you wanted to go to those extremes...it wouldn't have changed your motor much.

You've got a sweet engine there that you will have fun with. You pretty much designed a motor to sorta work with a cam that was pre selected. That works if all the parts are matched to the cam and each other. If they aren't, then usually you juggle the cam to make the other parts work best with each other. TQ is pretty much determined by engine size. You can increase and move it around a little with cams and compression changes. Making TQ at higher RPM makes HP numbers....making it across a broad range of RPM makes for a fun and fast play toy!

Now you know why it took me 3 full months of magazine articles to detail even a *bolt together* 555" motor without too many tricks really. Be careful what you read...and look for all the missing info!!

JIM

 

TSW , 427hotrod and of course 63mako,
thanks !!!!

words are not enough to thank you and the other persons who have kindly shared their knoledge and experience throughout this post.
above all in this last page there are very valuable inputs that i hope other forum members have appreciated and carefully read