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Car Forum / Chevrolet / Chevrolet Trucks / September 2006Questions about super/turbo charging on an inline-6 292...
Ever since I've gotten hip to the idea of swapping my 350 out for a 292 inline-6, I've been trying to find a better/different head for 292's. To say the least, the selection is, lacking... The only thing I saw that I liked was a custom "hybrid head" that was created from a set of SBC heads that had been modified by cutting off the end cylinders, then welding the two pieces together. It can be seen here: http://www.customdesignperformance.com/leo/cylinder_head.html It had the result of placing the exhaust on the opposite side of the engine, which may or may not be a good thing depending on how you'd want to place your components. If I were planning on adding a turbocharger, I'd prefer to have it all on the same side for a less complicated installation. My main question concerning forced induction is due to the nature of the stock head. Since it's usually a carb'd setup, how would forcing a charge of air into the top of the carb affect operation? I just recently read an article in Engine Masters magazine, where they installed a centrifugal supercharger that was feeding into the top of a carb, not the roots-style blower setup where the carb is mounted on top of the supercharger, thus *pulling* air through it. They experienced problems with carb tuning, and suggested that a MPFI setup would be the way to go The problem I see, is that the intake ports on the 292 head are shared between every two cylinders. How practical would it be to do a MPFI setup on this type of head? It seems you could either use 3 injectors (one for every two cylinders, pulling double-duty) or use 6, with 2 squeezed into each intake port. Neither seems like a good solution to me. I also thought about TBI, but then read that the Chevy throttle bodies aren't designed to withstand that sort of pressure and may cause problems and/or damage the unit, not to mention that it's not designed in such a way to allow fuel metering to keep up with boost. While I'm asking, is there another head (from another manufacturer) that might work with some minimal machine work? Something with the same dimensions but possible a different bolt pattern? On that hybrid head, they had to drill and tap new holes in the 292 block to accept it, but the cylinder all lined up. It would be nice, seeing as how the Ford and Jeep inline-6 heads that I saw have independent ports for each cylinder on the intake side. Wonder why nobody's made something like this for the Chevy?? The dudes that built the hybrid head said the labor would cost $2000, NOT including the donor SBC heads. No thanks! The ultimate would be finding a compatible DOHC head that had the correct cylinder spacing and adapting it to work on the 292. You'd have the benefits of the 292's long stroke, but the better flow characteristics and valve control of the newer head. Silly, I know...but I'm just imagining how things would be in an ideal world ;-) Thoughts, ideas, anyone? Just wanting to toss around some ideas and start an interesting thread. ~jp > Ever since I've gotten hip to the idea of swapping my 350 out for a 292 > inline-6, I've been trying to find a better/different head for 292's. [quoted text clipped - 57 lines] > > ~jp The factory 250/292 heads flow pretty well as is to make torque. Just a basic port and polish with a good blend in the valve pocket works real well. If you want larger valves they are also not hard to do, Clifford even has them for sale all done up and ready to bolt on. No real benefit from separate intake ports on the six. Oh and TBI works fine with a Paxton unit. Ran one for a couple years with no problems. Have seen them on carbed vehicles as well. Sounds like the folks who write for engine masters might want to talk to people who are actually using the units. If you want MPFI just make up a baffle that would separate the intake ports and have it welded to the intake manifold. Clifford even has a Weber FI setup already available. Pontiac had an overhead cam 6 in some cars. Not compatible with the 292 block though. My uncle has one stored in his shop.  SignatureSteve W. Yeah, I saw the Clifford units. Also saw a head on eBay minus the valves that had been ported/polished, and wasn't going for too much cash. Like $285 or something. I like the idea of fuel injection, be it TBI or MPFI or whatever, just for the adjustability of it all. I'm all carb'd out. Would the baffle you speak of (to divide the ports) just be a little metal wall welded in the center of the port to separate them into two individual ports? I saw the Clifford FI unit as well. Nice, but damn pricey. If TBI and a turbo as compatible, then that's probably the way to go, as it'd probably be the cheapest. The Engine Masters crew had trouble with *a* carb, then got much better results by switching to a different model. They got it running well, and it was making some insane power. It was a fairly plain Chrysler 440 and they pulled around 850hp out of it as I recall. They wrote a sidebar explaining why the first carb had trouble, and went on to say that FI would yield more consistent results, and would probably be easier to tune...that's all. Were you just blowing the boosted air down into the top of the TBI unit? What size engine were you running and about how much boost? Concerning finding an "alternate" head... Just for kicks, I looked up a few 4.0L Jeep and 258ci AMC heads. Those two are compatible with each other, but I couldn't find a reference to Jeep/AMC bore spacing on the web. Maybe I wasn't searching using the proper phrases. It's probably pointless, but I'm just curious. I know the bore spacing on the 292 is 4.4", or 111.8 mm, but can't find a thing on the Jeep motor. Of course the alignment of the valve guides and other things would have to be considered, but it'd be nice to know. It may be prohibitively expensive, but if it was similar *enough*, some filling and redrilling could make something like that work. Thanks, ~jp > The factory 250/292 heads flow pretty well as is to make torque. Just a > basic port and polish with a good blend in the valve pocket works real [quoted text clipped - 13 lines] > Pontiac had an overhead cam 6 in some cars. Not compatible with the 292 > block though. My uncle has one stored in his shop. You never blow down through a carb or throttle body with a turbo, you use what is called a " through turbo" boost system. The carb or throttle body is removed from the intake, and adaptor is put on its place, plumbed to the output side of the turbo. There is more plumbing on the intake side of the turbo, an adaptor and the carb or throttle body mounts to that. This is the set up the original Buick Grand Nationals used. The down side is you can not use an inter-cooler as the fuel charge is in the boost side, if you cool it the fuel condensates and drops out puddleing in the inter-cooler with explosive results. Your normal roots superchargeer is the same, the fuel mix is pulled in and compressed, Paxtons require an air box around the carb, and you jet them richer. I suppose it would be possible to change the injectors in a throttle body to accomplish the same thing. We used to use the injectors from 4.1 caddy engines in the throttle body of the 2.8 V-6 when installing 3.1 engines in their place. Cross flow heads are better than those with intake and exhaust on same side. One they flow better, but more importantly the exhaust heat is on the oposite side of the head as the fuel system. However with a good set of split headers, the heat transfer to the intake is going to be greatly reduced as mush as 70% less, and iff you wrap the tubes, probably 90% less. I would be leary of the set up home made from small block heads, I wouldnt trust it as far as I could throw it for a daily driver. Whitelightning Hmm... I'm starting to think the "Engine Masters" aren't quite as good as their magazine's name would imply. Here's the article with the supercharged 440: http://www.popularhotrodding.com/enginemasters/articles/mopar/bigblock/0609em_mo par_engine/ Either way, I don't like the way the setup you're describing sounds. Not being able to use an intercooler is out of the question for me. So if I do this, I'll need to engineer some sort of EFI setup. ~jp > You never blow down through a carb or throttle body with a turbo, you use > what is called [quoted text clipped - 22 lines] > > Whitelightning > You never blow down through a carb or throttle body with a turbo, you use > what is called [quoted text clipped - 22 lines] > > Whitelightning You can use a blow through system with a carb or EFI BUT you have to make a box that covers the carb and any sensors which control it and use ambient temperature or air pressure as a signal item. That air box gets pressurized and make the fuel system work properly. The problem is that it is not really a practical design when you can use the draft through design MUCH easier. SignatureSteve W. >> You never blow down through a carb or throttle body with a turbo, you use >> what is called [quoted text clipped - 39 lines] > is not really a practical design when you can use the draft through design > MUCH easier. As I recall fuel pressure must also be referenced (increased) to the increased boost. > Yeah, I saw the Clifford units. Also saw a head on eBay minus the > valves that had been ported/polished, and wasn't going for too much > cash. Like $285 or something. VERY easy to DIY. Just go slow and use your head. All you really need to do is use a gasket and match the head/gasket/port interface area. Then clean up the sand cast roughness. Clean up the valve guide are so it is shaped like a teardrop with the top of the tear facing the intake side. In the valve pocket you want to do a three angle valve job, then polish the port so that the high angle blends in smooth. On the outside of the pocket smooth out the edge between the cuts so that the seat only has the contact area left and the remainder is smooth. In the chamber just smooth out the casting and IF your doing over sized valves you can shape the area behind the valves to unshroud them and clean up any rough spots. CC them in and get them to as close as you can in shape. Just takes time and the ability to realize that bigger is not always better. > I like the idea of fuel injection, be it TBI or MPFI or whatever, just > for the adjustability of it all. I'm all carb'd out. Would the baffle [quoted text clipped - 3 lines] > a turbo as compatible, then that's probably the way to go, as it'd > probably be the cheapest. You can put forced induction on just about any engine. I know a guy with a turbo charged Briggs powered lawn tractor that he races. The baffle I made up is a chunk of aluminum 1/8" thick that I TIG welded to the intake with an extension into the ports I also used a mill to cut two slots for it to slide into. Not really needed but I have the tools. MPFI is easily done IF you can find a shop to burn you a chip, which isn't as difficult as it sounds. Use small block injectors out of a 305. Make up the fuel rail. Use a cam sensor off a small block and a computer off a V6. Sensors can be plumbed in easy enough and if you used one off a vehicle that used a MAP sensor instead of a MAF it gets easier to map out the program. > The Engine Masters crew had trouble with *a* carb, then got much better > results by switching to a different model. They got it running well, [quoted text clipped - 3 lines] > that FI would yield more consistent results, and would probably be > easier to tune...that's all. Yep some carbs are just a PIA to work with. FI is a MUCH better way to go and can be tuned to suit your vehicle better. > Were you just blowing the boosted air down into the top of the TBI > unit? What size engine were you running and about how much boost? Set up as a blow through unit and depending on the pulley OD on the Paxton I had from 7-13 pounds. This was on a 231 in a 78 Olds Starfire GT (Think Chevy Monza). With the street pulleys on and at 7.5 PSI I was getting close to 330 hp. Full out I'm not sure of because the engine snapped the crank on the second pull! The first one showed 480 hp and that was not dial in yet! Salvaged the good parts for the future. The blow through was OK but you have to pull the airbox apart to do tuning. > Concerning finding an "alternate" head... Just for kicks, I looked up > a few 4.0L Jeep and 258ci AMC heads. Those two are compatible with [quoted text clipped - 6 lines] > prohibitively expensive, but if it was similar *enough*, some filling > and redrilling could make something like that work. Not really needed. The factory head is a nice unit and with minor work will do a better job. > Thanks, > > ~jp >Pontiac had an overhead cam 6 in some cars. Not compatible with the 292 >block though. My uncle has one stored in his shop. I had forgotten all about that engine. It has been a long time. Jeep had one too in the 60's in early Wagoneers. I would have to check as it may have been the same motor as Jeep bought V6 from GM in 60's (rights and all) and then afre AMC bought Jeep out, they sold it back to GM in mid 70's as GM wanted it back and AMC did not need it. ----------------- TheSnoMan.com Was that the Jeep Tornado engine? Impressive specs: http://en.wikipedia.org/wiki/Jeep_Tornado_engine "...4.38 inch stroke" "...210 ft·lbf of torque at 1750 rpm" ~jp > I had forgotten all about that engine. It has been a long time. Jeep > had one too in the 60's in early Wagoneers. I would have to check as [quoted text clipped - 3 lines] > ----------------- > TheSnoMan.com >> Pontiac had an overhead cam 6 in some cars. Not compatible with the 292 >> block though. My uncle has one stored in his shop. [quoted text clipped - 6 lines] > ----------------- > TheSnoMan.com Same design but made by AMC instead of Pontiac. The V6 that Jeep used was the 225 which was then sold to Rover of England and then GM brought it back as the 231. Rover used it as a 225 BUT with aluminum block. I picked one up to see if I could turn it into a stage 3 engine for a GNX I had. Found out when boring it that Rover had problems with core shift in the block. Saved it as a .040 over sleeved engine but didn't finish it yet... Sold the GNX 2 years ago. Go back a few years and it can be interesting looking at who used what from who.. AMC used just about anything bought from everyone! Makes it fun sometimes if you have one and need parts. SignatureSteve W. > Same design but made by AMC instead of Pontiac. > The V6 that Jeep used was the 225 which was then sold to Rover of [quoted text clipped - 8 lines] > AMC used just about anything bought from everyone! Makes it fun > sometimes if you have one and need parts. Gotta disagree with you on the Buick/Range Rover thing. The engine that Buick sold to Rover was the 215 aluminum block V-8. This was a great engine, used in the Buick skylark and special, olds f-85 and Pontiac tempest(the one with the front engine, rope drive shaft to the transaxle in the back) for 2 years, First six months there were engine problems , torque specs for the head bolts were too high, as where the mains. After they lowered the specs it became a damn good engine. But Chevy had the 283, and the 327, ford had the 260 and 289, mopar had the 318, and the American public was on a numbers thing, and cars were getting bigger and heavier. With 4 barrel carb (this was the Buick 4100 engine) it put out 200 hp @ 5000 rpm, and 240 foot pounds of torque @ 3200 rpm and had 10.25 to 1 compression ratio. Not bad for an engine not much bigger physically than a 4.3 V-6, and almost 75 pounds lighter. I've been looking for a Skylark most all my life. I want a '63 convertible with the 4100 engine, Baby Blue, although I believe they called it robins egg blue, with blue leather interior, black top, factory AC, automatic. I've come to a point in my life wherein I realize its just a dream, unless the lottery gods smile upon me. Oh here's a tidbit, in the original movie 'The Fugitive" Dr Kimble's sister in law picks him up in a 63 Buick Skylark convertible, and in My Cousin, Vinny, the two boys are in a 63 Buick special, and real killers drove a 63 Tempest. Rover used it, British Leyland used it, they cut the engine in half and used the left bank in the Triumph TR-7, they used the whole thing in the TR-8. They used in in the MGB-GTV-8 for three years, 1973-1976, sadly never imported here. It made it's way into the land rover. It was probably the dumbest thing Buick has ever done. The Jeep V-6 was called the Dauntless, and while Buick designed it, they never built it, Kaiser built it in 225 cid. Later Buick bought it back from jeep who was no longer using it, they stopped with the introduction of the CJ-5. As much as I dislike AMC, they produced their own engines, and while some shared the same CID as others that's all they had in common, There is nothing interchangeable between the 327 AMC engine and the Chevy 327 they are totally unique engines, AMC sure did like using everyone else's charging systems tho, as well as motarola which makes for some fun I will agree.. AMC straight 6 engines didn't share anything with any one else's ether. Whitelightning >> Same design but made by AMC instead of Pontiac. >> The V6 that Jeep used was the 225 which was then sold to Rover of [quoted text clipped - 47 lines] > > Whitelightning Yes Rover had the 215 V8 in aluminum. They also had a 225 V6 in aluminum. It was only for export for one year. They stopped production when they decided it was underpowered. Which it is when stock. Mine came out of Africa if the seller was correct. Hard to find them because they basically scrapped them all. On the Poncho there was a Tempest for sale in the local want add digest. Ad said it was in great shape. A guy I know looked it over and figured it had at least a gallon of bondo in the quarters! SignatureSteve W. >Yes Rover had the 215 V8 in aluminum. They also had a 225 V6 in >aluminum. It was only for export for one year. They stopped production >when they decided it was underpowered. Which it is when stock. Mine came >out of Africa if the seller was correct. Hard to find them because they >basically scrapped them all. THey actually used that block for many many years. I had a friend that had a 63 Cutlass in late 60's with a 215 4bbl and as I recall it ran quite well. Those engines had oil consumption issue though because they were not sleeved. ----------------- TheSnoMan.com >> Yes Rover had the 215 V8 in aluminum. They also had a 225 V6 in >> aluminum. It was only for export for one year. They stopped production [quoted text clipped - 8 lines] > ----------------- > TheSnoMan.com They did the same thing with the 225. Now that this one has been bored and sleeved it should last a while, IF I can find a vehicle to install it in. Still have a Starfire but it has a very stout small block stuffed in it currently. I have a parts version here but I'd have to make a new chassis for it since it has terminal front sub-frame rot. SignatureSteve W. >The Jeep V-6 was called the Dauntless, and while Buick designed it, they >never built it, Kaiser built it in 225 cid. Later Buick bought it back from [quoted text clipped - 6 lines] >agree.. AMC straight 6 engines didn't share anything with any one else's >ether. AMC built some very fine motors on their own. While their cars lacked, their motors were very sturdy and a welcome addition to Jeeps. I have a 79 J20 that I bought off of original owner 21 years ago and it has had a very hard life and plowed snow for many years too and the AMC 360 it is still runs smooth and strong and has low RPM torque that would shame a 350. Now it is a barn queen as it is awaiting restoration to like new one day (body is not rusted to back and it is straight and complete too) but I can go down and fire it up and it will start with little effort even after sitting for several months. I had it out in Montana in mid 90's and I even started it once at 38 below without heat to plow with (forgot to plug it in) and it started with surprizing little effort. Few cars even today could do that new. ----------------- TheSnoMan.com |
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