John Scott

Jeff, any Chevy dealer should be able to get the Performance parts catalog. Beware, not all dealers charge the same. I heartily recommend Sallee Chevrolet which also carries a wide range of performance parts in addition to the Chevy line. WWW.Salleechevrolet.com They have provided me with excellent deals that not even the major performance houses can match. Sallee also run a very nice speed shop with inovative engine builds. Check out thier personal line of 383 450 hp ZZ450s. This is personally becoming my favorite chevy source. Additionally, Tom Sallee, parts Guru, is very knowledgeable and willing to help. JS

All good points. I'd like to emphasize the importance of good rods and bolts to any performance engine. Loose a rod and the rest of the engine is garbage. Note that tensile loads on a connecting rod increase exponentially with RPM. A high hp SC'd load at lower rpm often creates way less stress on a rod than naturally aspirated lower hp at high rpms. At the very least prepare stock rods by the book, Chevy power manual, by magnafluxing, polishing beams, shotpeening, resize balance the whole recip assem. Its not that expensive and well worth the price. I haven't heard the limitations of the PM rods, Chevy claims up to 500 hp. Since you won't have a "matched" recip assem, BALANCE! Racing rods might not be a bad investment. .02 on forged pistons: On naturally aspirated hypereutectic are great! Alcohol engines can run extremely high compression w/o detonation. On a super/turbo charged engine never risk anything less than forged. Scottie, I admire your courage and faith in your engine fuel/management system. Even though you've designed everything to avoid detonation, no system is fail safe or perfect. Just the other day you found you were running a different fuel pressure than you thought. Too far the other way and your hypers would be gone. For $100-150 or so more forged is well worth the price. In a naturally aspirated engine, especially with the low compression ratios pump gas requires, you can put up with quite a bit of detonation before really messing something up. Under boost it can be instantaneous. You may never even hear it. Yes it can destroy both engines, but forged give a substantial margin of safety. If I didn't have forged, I know my pistons would look like whiffle balls by now. JS [This message has been edited by John Scott (edited February 17, 2001).]

To only have a LIVE CAM in Mike's Garage. The best never rest!....so Mike, when do you eat and sleep JS

In the 70's bought a 425 Old engine that used to reside in a local machinist's corvair. It was wheelie happy, so he pulled it for a SBC with a little less torque. JS

What were/are your 1/8 MPHs? Surely the GN has a much higher 1/8 speed?? If you're starting from a higher speed then its going to take lots more power to get a 27 mph spread. JS

Its no big deal to blow through a carb. You don't need a box like the old Paxton design. All you have to do on a holley is seal off the hole where the choke linkage comes through with JB weld, mill air horn, and put in plastic floats. It works great, but not as well as FI. For the sake of argument look into www.customcarb.com , then call one of their staff. They'll tell you a very convincing line on blow through carburetion. Have plenty of real world examples to back up their claim. Worth looking into if you are interested. JS [This message has been edited by John Scott (edited February 10, 2001).]

I wouldn't expect any gains from the cooling effect of blown carburetion. FI can be tuned throughout the rpm range more precisely. JS

RGB, welcome aboard! 85 was the first year for chevy to start the Vortec. Up until 92 4.3s were pretty much the same. 86 went to one piece seals, 87-up used roller cams.Somewhere along the 4.3 line the motor went to a balance shaft design. I don't know diddly about it so you'll have to research the performance potential. I've heard the heads from 93-96 are preferred. Best stock rods are from 96-98 models. This won't be a bolt in as custom mounts will need to be made. Look into modifying Harmons Chevy parts 1 800 851 2433, for their chevy II conversion mounts. They look very similar to what I concocted from two old Z motor brackets and some pipe. Astro pan will fit fine. I am currently running about 3" clearance off the ground with mine. I can send you pictures of my mount system if you'd like. I'd avoid the truck transmission. The gearing is all wrong for the Z, way too low 1st. Torque rating is really wimpy too. No provisions for mechanical speedo with w/c tailhousing. Dont underestimate the v8 equipped with aluminum heads, water pump. manifold, for a really great weight balance. It will be an easier swap. Performance additions are lots cheaper and you start out with more power. If you are determined to use the 4.3, once the motor mounts are fabricated, the rest is straight forward. My weight balance is 49/51. JS [This message has been edited by John Scott (edited February 09, 2001).]

An engine may take only what it needs, but the low end mixture velocity is going to really suffer on the big carb. I'd bet the 600 would be closer to a bolt on than a 1000cfm dominator! You might get the dominator to run, but after how many modifications? I know you weren't talking Holleys, but for the sake of argument, Holley engineers ran tests on the 350 HO and found the 750 to be the best 1/4 mile performer. (600s were also tested) Vacuum AND mechanical secondary models both performed well. Redrilled shooters primary and secondary to .040 were used to increase throttle tip in on the double pumper, and .035 on the vacuum model were the only major changes. Jetting and springs were optimized. Center hung floats are mandatory for hard acceleration. Katech's 610 hp small blocks uses the 750 as well. Sounds like a pretty flexible carb! JS [This message has been edited by John Scott (edited February 03, 2001).]

Scottie, as usual, I'm impressed with your professional systematic approach to a problem. It sounds like you're on your way to better time slips. Your pump reading of 24 lbs has me interested. Was this reading over and above a baseline pressure, or the actual pump pressure? Since the rule of thumb for SC'ed carburetion is 7 psi over max boost, the 24 lb is about perfect for 16-17 lbs boost. Sorry I can't remember, but what fuel pump/ regulator are you running? Prices?

Scottie, I'd say you're right on for either SC or Turbo application. For those running computer-less, I would be hesitant about finding that light detonation point under high boost, though. W/O a knock sensor, or some way of reading O2 you may never hear it before its too late. Start way rich and back down in small steps. Your techno set up is fantastic. JS

RE Scottie's question. I think looking at the torque ratings of the transmissions availible, the T56 offers the best solution for the price and avalibility. For most, and especially a street driven car, the double overdrive isn't so much a peformance issue as just a great way to keep your mega buck engine intact on those long hauls. You still use 3 or 4 gears at the track. Sub 2000 rpms at fast hiway speeds is a really cool way to travel back home...and yes the milage can be an issue too. JS

I was always told that when the synchros start to wear you can experience the popping out when you let off. You might want to throw that ? at a transmission shop to confirm. JS

Yo Myron, post your professional jetting, PVs squirters, everything you can...just as a reference for the rest of us. I like to see what combos work with what. JS

I just got MSA sways for my 240 for Christmas from my wife. (Finally!!) Kit is complete with fasteners, links, and spacers etc. Front installation took 10 minutes to R&R! Rears will take considerably longer if you have a 240 w/o stock rear sway. Still should be no big deal. Quality overall seems excellent made of automotive grade spring steel, forged ends, urethane, nice hardware. Just the front made a huge difference! JS

Is it just a gimmick or worth while? Has Speedo, tach, and shift light. $185 www.defi-shop.com I like the heads up idea. Never liked taking my eyes off the road, especially if its gettin' sideways! JS

My 600 billit impeller complete with all brackets, carb hat, and pulleies was 2071.00 I'm sure this has gone up. In all fairness I inquired about the centrifugals hp requirements. It takes about 60+ hp to turn a 600B at 15 psi, give or take. On a Smallblock this would equate to roughly 600hp. Sounds like about 10%. I don't know what the back pressure equals to hp loss in a turbo motor, but its not that high. Also, as Morgan mentioned, the turbo impellers are capable of more speed. Centrifugals are closing the gap, but have a ways to go. Advantage: Turbo. JS

Sorry Roamer, Welcome to the site Hope you can sift through this and come up with some good ideas for your project. Don't discount the sbc for its high rpm potential. I ridden in some 10K rpm cars, (and one truck actually). Incredible! I think you'll find that the high rpms won't be needed with all the v8 torque, if that's your direction. If you can afford it, a small engine will benefit more from a turbocharger. Morgan, I'll agree with you that the turbos are a more effecient power adder. You say superchargers are "universally more inferior" Turbos require the highest initial investment. complexity, and require EFI. In my mind, this isn't a superior point. Many here a drag racers. Power adder of choice? Superchargers. Why? They are versitle, inexpensive to turbos, and work REALLY well.A single DM3 procharger will pump out 2900 cfm! That equates to over 1600hp potential! Need to switch from your V6 to a sbc V8. No need to change a compressor housing. Mine can be removed and bolted on any smallblock in less than 30 minutes. Ease of installation goes to the supercharger too. Reliability? Most can come with a 3 year warrantee. I have over 5 years with only a $3 seal that needed replacing. If you dig through the archives you'll note I was proclaiming the turbo a superior unit from early on. I'd prefer one under my hood. Yes, turbos are mechanically more efficient. But they cost waaay more, are more complex to configure to a non-traditional engine in a Z. I'd rather be driving my car right now, blowing the doors off the competetion, than saving and dreaming about a high tech turbo. You know what? I like the nasty whine that annouces the arrival of the winner, too. JS [This message has been edited by John Scott (edited January 04, 2001).]

quote: Originally posted by Morgan: I had a meaningful reply all typed up just now. But I deleted it because nobody cares and someone would get their panties in a wad and cry to have it deleted. Let him believe what he wants, I no longer have the time to worry about people who believe such ludicrous misconceptions and so badly want to continue to do so. Morgan, you're missing something here. Its OK to have differences of opinions without the hostile angry remarks. We're talking cars, not life or death ultimatums! I'll be the first to add that the Superchargers are not the power robbing complicated, expensive systems as you proclaim.I'll agree that roots type blowers are inefficient, but beg to differ with centrifugal. Yes turbos offer more hp through out a wider range and are superior in most regards. This also depends on application, engine size. The adibiatic efficiency of centrifugals is nearly identical to turbos. Plus you dont have the high underhood temps. Figure in the cost of one of the new no-lag turbos for a custom engine,it won't be a bolt on(!) tubing, fuel system and you're talking thousands more than a good supercharger.You can have a bone headed simple kit for about 2K that will make a ton of hp. A single sepentine with a tensioner is not complicated. To say that they don't make big boost is untrue. How much is a good #? 12, 18 25? A turbo is hugely more difficult and expensive than a centrifugal, except if your platform made one readily availible from the factory. Morgan, I wish you lived near by and we could trade rides. I think that my 16 psi pump gas driven Z would have you thinking differently about superchargers. No lag, no detonation, no overheating, as docile or wild as you want. Reliable? Yes. If you're ever in CO, I'll be glad to let you take it for a spin. JS [This message has been edited by John Scott (edited January 03, 2001).]

I know Hybrid member, Rob, has been running one. My driveshaft shop said there were fewer harmonics with the aluminum shafts and ran truer. A bit more pricey, too. JS

Yes I love the engine. How many can say they've run the same engine for 12+ years? Only 2 rebuilds! The 4.3 has been used in many forms of racing from championship drags, to ASA gran mark series, to Nascar Daytona Dash. Someone can probably figure what it takes to make a 3500 lb Syclone with a sponge of a transmission transfer case run a 10 sec. 1/4, but its some serious hp! The V6 has been nixed recently from the big race series. The Brodix heads will fit and are worth big hp gain. Down fall is all aftermarket heads need custom exhaust and an expensive manifold. The stock heads are the biggest restriction of power on the 4.3. But, as I complained before everything is really expensive. I've been searching for deals for years! The best I could do to my block would be the heads and 4 bolt conversion. I lose my bearings in about 4-5K miles. Way too much flex going on. I plan on enjoying it for a couple of years to come and will try to wring every ounce of power out of it. I'm just saying the next round will be something I know will cost less and make way more power. Remember, I love procharged engines!! JS [This message has been edited by John Scott (edited January 01, 2001).]

So if any of you plan to race on ice and snow, off road baja, wet tracks, then the AWD will have the upper hand. The AWDs are incredible on the Pikes peak hill climb! I prefer dry pavement. I'll gladly accept defeat in the other conditions. I don't race on wet pavement either. Won't take it up a jeep trail either An AWD Talon or Syclone can smoke just about anything in the stoplight wars. F1 and Indy are pulling some serious Gs weather its mandated or not. If they mandated fwd you'd see the speeds decline. [This message has been edited by John Scott (edited January 01, 2001).]

I'm a 4.3 fanatic. I've had more fun with this set up than any of my big V8s to date. There's an amazing amount of aftermarket parts availible and considerable power to be made in a relatively tidy package. I've also enjoyed having unique powerplant, that quite honestly has whipped the pants off of every car it has encountered on the street. If I could win the lottery I'd continue regardless of price with this great engine. The reality: My dream engine is becoming an overpriced investment. For starters, the bow tie block has jumped from an expensive $900 to a unaffordable $2500. Yeah, the new one is CNC machined with splayed four bolts. Throw in an aftermarket forged steel crank for another 2 grand. $1700 more gets you a set of really nice brodix heads. Gee, I'm already over $6000 and still haven't bought any rods, finished the bores, balancing, pistons, cam shafts, manifold etc, etc. So for about $7000 you can have a really, REALLY stout 4.3. Aluminum block? Don't even ask! I've come to the conclusion I won't be satisfied with the stock block and don't want to spend the extra to "four bolt" it with out at least a head upgrade. $500 + 1700 + the thousands I've already spent is too much for me. I've read about the 500 hp naturally asprirated and 700+ turbo'd 4.3s, but there is a simpler and cheaper way to at least as much power. SBC! So, I plan to enjoy the 4.3 for now. I think I'm on to some big power gains with the jetting and fuel pressure tweaks. I'll continue to abuse the heck out of it and as in the past it will perform exceptionally well. Next time the bearings are shot, it will be time for something newer bigger, more powerful... and less expensive! JS

One of my favorite "set ups" is to have a front drive rice rocket chasing me into an off or on ramp, then really accelerate through the corner. Mine has a pretty poor suspension, but never fails to smoke the RR. Ever seen a high powered fwd car try to punch it in a corner? The front loses traction and the resulting undrsteer puts them off the road! Fwd had come a long way, but will never match a rwd, especially in really high hp/wt vehicles. Most of the V8 conversions end up with a much superior weight distribution than even the straight six., nearly 50/50. A V6 placed like mine will put you in at 48/52. The integras might be good handlers, but how many indy, formula, you name it are fwd? NONE! Even the awd is second rate to the rwd except in wet road conditions. JS

Anyone looking for the ultimate manifold for their 4.3, a raised runner intake is for sale on ebay for $99 starting. ebaymotors item #531412172 Not one bid has been placed and it should go for cheap. The base alone is over $300. Super flat torque curve. I'd love to have it in my parts collection, but w/o work for another week, so finances are low. !@#$%! JS [This message has been edited by John Scott (edited December 29, 2000).] [This message has been edited by John Scott (edited December 29, 2000).]