IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: bcn30141 on December 06 2013, 05:01:42 PM
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Well as my story goes ...all was well until quarter way into fourth gear...then all there was is a huge cloud of smoke. :rock: I was in the ball park of 28 lbs of boost
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Tear Down
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Considering roller can since I've gone this far...
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What fuel were you running, 91 and alky for 28lb boost?
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I was using 93 and alky set on 8....I had a conservative tune by use of my Gen2...kept around 24 degree on timing, had about 785 all the way through third and zero knock except between shifts...it was the first time I really ran it hard into fourth-
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You sure did a number on them. I would never try to run that hard in fourth gear as it puts a heckuva load on the engine and is an invitation to break something. Running that much timing on top of that much boost just made it more of a bomb waiting to go off.
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I'm learning something new every time I drive this car it seems Steve....just a a while back I didn't even know what the function of a knock sensor was or even the meaning of those numbers jumping around all over the place on my scanmaster...t he last hot rod I had was a 650hp 2003 supercharged cobra modded out and it had no problem spraying 100 shot of nitrous in 5 th gear at 170 mph. I would think the car could handle a little fourth gear but it didn't. I am looking for a descent roller kit to match my 2800 stall, 1.94 1.50 ported iron heads, CPT 61 DBB turbo....any suggestions on what lift and duration I can get away with? I can say one thing ...I have learned a lot! Thanks!
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I would stick with something in the 206 to 208 deg range at 0.050". Whatever lift comes with a cam in that range. It will be close to 0.500"
These cars respond more to boost than the cam-at least on the average street car. Extending the rpm range a bit with a cam may gain more than that gained from duration or lift because it makes it easier to keep the car in third which accelerates better than fourth. Even a stock cam with decent valve springs should normally run better in third thru the lights than it will making another shift to fourth. Obviously one wants to make sure the car is shifting around 5200 or so out of first and second. Some shift considerably lower and that makes it hard to reach the line in third.
Not only does fourth increase the load building more heat, but, when you combine that with the drag coefficient of a concrete block, it really has to work hard to accelerate past 100 mph. I suspect a TTA with equivalent drivetrain will et a couple of tenths faster than a Regal just on aerodynamics.
If I were running one hard in fourth gear, I would probably run about 18 degs of timing because boost seems to make more power than timing and reducing the timing keeps combustion chamber temps from flaring as badly. I am using "boost" in a generic sense when I really mean how many air molecules (density) are crammed into the cylinder. In any case, I would not be looking for prolonged running in fourth. These are not top end machines.
Another factor is that it is easy to blow a hg without actual detonation-particularly if one is running stock head bolts. The head lifts a bit because the bolts stretch and the gasket is not clamped well. This is more prevalent when running shims because there is no cushion in the gasket to maintain the seal. It happens with conventional gaskets as well and studs are worth it on a car that is going to be pushed to the limits.
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I am seriously considering taking out then engine to stud the heads, heck it already has studded rod and main caps, eagle crank in all,...I wonder how those straight six turbo supras handle there crazy boost at high top ends like they do....is it totally bennificial to install an rjc plenum plate or upsize the MAF, everything is under pressure in boost....I can see the benefits with a NA engine or putting on a 4 inch intake kit on a turbo car. I hope one day I can run with you big boys , hehe
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First, there is no need to pull the engine to install studs. ARP has allen headed studs that can be installed thru the heads.
And the Supra was around 2 liters with very small pistons and low reciprocating weight on the rotating assembly. Given the small displacement, they had to be twisted high to get any power. Put an overhead cam system designed for high rpm on top and they were designed for the task.
The Buick was not designed for high rpm but was modified with extremely heavy pistons for low rpm, turbo'd operation. Buick created an Indy engine with lower displacement to meet the rules as well as some nascar versions. These engines used a beefed up assembly/block and were twisted around 8000 rpm with some success. Billy Anderson built an engine one year that was around 200 cubic inches that screamed at top rpm but it was still large compared to a 120 cubic inch Supra.
Totally apples and oranges
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I hope one day I can run with you!! That's an experience to be had but you seem to have it under control. I bet that Cobra was a heckuva lot of fun to drive!!!
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Steve I applaud you car knowledge ..... I heard it was a pain on the passenger side to set the head in place on studs with the block still in the car....I'm also thinking I could have some gasket material in my pan. Plus I won't get a back ake when I go about torquing the heads down with it on a stand lol hehe....
Phil here are some pics of my Cobra...it pulls very strong...
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Oh Nevermind Steve ....I see what your saying...put the heads on and run the studs in and tighten down all the nuts....gotcha
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First, there is no need to pull the engine to install studs. ARP has allen headed studs that can be installed thru the heads.
And the Supra was around 2 liters with very small pistons and low reciprocating weight on the rotating assembly. Given the small displacement, they had to be twisted high to get any power. Put an overhead cam system designed for high rpm on top and they were designed for the task.
The Buick was not designed for high rpm but was modified with extremely heavy pistons for low rpm, turbo'd operation. Buick created an Indy engine with lower displacement to meet the rules as well as some nascar versions. These engines used a beefed up assembly/block and were twisted around 8000 rpm with some success. Billy Anderson built an engine one year that was around 200 cubic inches that screamed at top rpm but it was still large compared to a 120 cubic inch Supra.
Totally apples and oranges
The Supra I m referring too is the early mid 1990's 3.0 TT that tuners single turbo out, but I suppose they work just the same as your explanation of the other....I think a lot of it has to do with the DHOC....
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yes, it is easier to pull the rpm out of a valvetrain that is designed to be stable at high rpm...and if you compare the weight of a a piston/rod from that engine to the weight of one from a buick, it becomes obvious why the assembly stays together at high rpm
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I'm also leaning towards the idea that my blow out had something to do with not having any wide band input.... I have a Gen2...thinkin g of getting a NGK wide band set up and plugging it into the auxiliary of my gen 2...take out the TT chip and put in a extender chip from full throttle. Just input my desired air fuel and go with it...any thoughts? I remember keeping the air fuel around 12:1 on my supercharged car...what is best for the buick turbo? Thanks!
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12:1 A/F aint it maybe at 12-14psi youll be ok
do that and youll be doing those gaskets over again
my target on alky/ 93(its 10% ethanol blended already) is 10.5 A/F and timing at 18-19 degrees
and that 10.5 being its a mix of alky and fuel is based on having enough temp drop from alky and enough fuel to support the hp without alky
take your injector rating x injectory duty at traps and youll have the flow per injector, x 6 (injectors) , x2 (bsfc.5lb per hp)... should=HP
take your mph and weight and figure the HP,plenty of online HP charts out there .
the fuel numbers should match provided you maintained the AF ,fuel pressure stayed 1:1 during run and your boost wasnt a runaway and was somewhat under control,
too low on fuel means and you have too much alky ,
too high on fuel you dont have enough alky
its also a good idea to log the air temp at plenum so you can evaluate the alky effect , i look for ambient or withing 10 degrees during a pass , in winter 10 degrees warmer is ok , in summer 10 degrees cooler is ok
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After 12 years of playing with widebands, I have come to the conclusion that there is no magic in a wideband unless one has a fully programmable aftermarket fuel management system and the knowledge to use it properly.
Using the factory ecm, one tunes just like he does with the narrow band factory sensor-As lean as possible without any timing retard from detonation.. Obviously this depends upon ambient conditions, quality of fuel, amount of alky sprayed, engine combination,street, strip, or wot to top end, etc.
One tunes for the worst case in the intended use. Typically, this might be some where in the upper tens a/f wise.
Those who tune to a magic number given to them by someone else tend to either go slow or blow them up.
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1.94 1.50 ported irons and my block I'm proud of which has been balanced through and through. I also found a kink in the fuel line leading up to the rail...maybe that was my detonation creater....
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Pistons cleaned up
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That cobra is a beaut!! I've always loved those things
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Heads cleaned up...looking forward to installing stud and roller kit....I'm not sure if I will need a new rocker assembly, not even sure if mine is stock....I need to learn about rocker sizes and types, if I can use mine or if I have to get another etc etc
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you can use stock rockers with a roller cam I would at least use braces (saddles) the stock shafts tend to break with the extra spring pressure and you have to measure your pushrods to get the correct preload.
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FYI your 1.94 intake valves look an awful lot like stock (hell they even have the GM casting) , might want to take a caliper to that
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They are Chevy intake valves from small block V8. They are stamped GM. I haven't calipered them before though....when I put in the new springs for the cam I'll check that out.
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Well at least that's what a parts list on a receipt said.....so I calipered them and they show a size of 1.7 something...th at's a bit short of 1.94... Oh well, I'm not special any more lol
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Pace car is it needed to relap valves or just keep them matched up.?thanks
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wonder how much trouble those G.M.'s can cause?
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for roller cam , the cam is a drop in the block (unless its a billet then you had better do your homework ) but the heads need to be prepped for the cam lift
youll want to cut the exhaust valve guide down for clearance as well as PC seals the exhaust valves should be replaced because the stock ones have a groove cut into them for oiling and a PC seal wont work with the stock valve , so you need to swap them out for a valve without a grooved stem (the TTA exhaust valve , manley or ferrea valve)
just so you know to fit a 1.94 on stock iron heads requires moving the valve guides over.
you will need new springs for a roller cam and new pushrods measured for fit after the heads and cam are installed ...dont assume the vendor sent you what you need in regards to adequate spring pressure or pushrod ..measure first
if you want to do roller rockers youll need to clearance the pedastils and measure for pushrods with the rockers you intend to run , stock and roller rockers take different length pushrods and the adjusters arent there to fix measurement errors , they are there to obtain closer preload matching and to get preloads closer to zero lash on performance lifters ..oh yeah.. all roller lifters arent created equal or take the same preload
as far as heads go the champion irons out of the box are hard to beat for the price , 1.775 1.50 valves , cnc ported , they will do springs for what you need ready for most roller cams -valve guides cut with pc seals- pedastils clearanced for roller rockers, head surface ready for MLS gaskets and the vc rail smoothed , they have been 9s and faster
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I was looking at this kit from full throttle...the y say I can use stock rockers....
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you can and the shafts may break with the added spring pressure required for roller cam
i run a roller on my 87x but i have solid shafts
that kit usually includes the less expensive and usually quieter morel lifters .
fullthrottle includes pushrods with kit but you should ask to have them hold off sending them until the cam is installed and measured using a pushrod tool .. allowing for proper preload
they have morell lifter option vs comp cams lifters and they both take a different pushrod length because of different lifter disc height (about .150" difference)
and limited travel race lifters may need you to order several lengths of pushrods to get it all correct to use stock rockers because they are set with almost no preload , unless you are after a class that wont allow roller rockers i would reccomend rollers rockers if you decide on limited travel lifters
roller rockers vs stock rockers will differ the rod length another .100"
once you have the number that will work with your setup give them a call and they are very quick to get out what you need
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What length would I be measuring. The longest distance from lifter to rocker after the cam has rolled off the lift? This starting to get technical but I'm trying to hang in there lol
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cam at base (intake lifter up check exhaust and vice verse)
with tool installed and rockers installed and torqued ,adjust tool for zero lash ,then remove tool and spin it longer to add for desired preload, then measure tool and order push rods
the roller cam also has to go in with .005-008 end play between the end of cam button and the timing cover(installed and torqued)..they provide the adjustable cam button with shim set but its your job to add shims as needed to get proper end play
and its your job to verify timing chain length ,they provide a comp cams std timing set (its a double roller so you cant use the tensioner)
on a block like yours with billet mains , fitting steel caps requires a line bore and usually moves the crank center line closer to cam (some shops cut more than others) it usually requires an undersized timing set (rollmaster) , or a chain set that can use the tensioner (ta perf) but using a tensioner to take up looseness will require degreeing in the cam as a longer chain than needed will retard the cam
and be sure to check the gear/chain clearance on timing cover , they usually hit double rollers
seeall basic stuff... for buicks
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Everyone's information is priceless, thank you.... What do you guys think about this....using a higher ratio rocker on the exhaust valve... Wouldn't a higher exhaust lift assist a turbo car? Say 1.55 on intakes and 1.65 on exhaust...
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Hmmm So are these engines at the fault of pushrod old v6 style that we cant run all the way up to fourth gear. Because next year I got a few call outs from some buddies with little Vtec Hondas and a few other small cars that I kind of laughed off. Will the GN win from a 30 mph roll on the highway? Or are these cars only deadly from a Dig? I remember my dad telling me a stories of a stock GN on the highway getting beaten by a stock 5.0 Monte SS back in the day. One thing about the supra is I hear they are torn down very often for rebuild when making any power they shouldn't be making.
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My top end blow out had something to do with a pinch in a curved part of my metal fuel line coming up to the fuel rail, I think it started suffocating from fuel loss and detonated. I would to put in some sort of braided hose fuel line set up coming in and get those SS style lines outta there. I ain't going to run through fourth anymore to be on the safe side.
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when my 86 was on TT chip and a 2004r running gta rims with 25.5" tires (mt255/50-16) i would always use fourth gear sometimes as soon as 400ft out , other times i would hold off until 120 mph , and I used OD for several hundreds passes at around 600hp trapping 125-129 and i was running a flat tappet 206 cam and ported irons that would pull over 6k without any issues but with 4th i was trapping around 5400 with a loose artcarr 9" that slipped over 17%
with 28" tires i wouldnt use fourth and really didnt need it
, now on a th400 i only have three gears and thats been working out ok .
if plans are to use fourth make sure you have the fuel and the tune are good with room to spare , those that are running out third and just on the edge will find fourth gear will be more than the tune can handle
keep timing low until the fueling is worked out , only after the fueling is good should you add timing