View Full Version : Big block TT power increase?
Hey all, a hypothetical question.
Say I built a 427 Chev motor, and then whacked two turbos on it. What (ballpark) power increase would you expect I'd get, as a percentage, and on what kind of boost?
I don't want to get into academia (what kind of turbos, what wheels, trim, all that stuff - coz I don't get all that stuff yet :D), so just give me an average scenario...
I would want the motor to be fairly tractable off-boost, which I guess a big block would be by nature, but for it to be a bit of an animal on-boost would be nice. :)
Approx. cost of new turbos and having piping made up etc? Aftermarket management would be a must I presume? What internal mods would need to be made to a stock EFI BB Chev to allow for this operation?
Also, if my engine bay is that cramped that I can only have stock exhaust manifolds, not extractors or headers, would this seriously limit performance?
Fire away!
Tex
meggala
02-07-02, 12:37 PM
Tex forget the is turbo crap on a 427 just rebuild it up the compression and whack in a farken great big cam, do the heads and find a carbie big enough. believe me you will be happy 20 years ago I had the pleasure of hearing a race 427 in a vette and it was the sweetest sound ever. and gave a great foot massage from 50 ' as well. through the straight through side pipes
meggala
But just to answer the question, you could easily make 50% more power at say 12 psi than an equivalently built (but with NA compression instead of lowered for turbo compression) NA motor.
This would be very mild with off the shelf turbos like CT26s (off 3.0l Supras) or a pair of T04s.
With more appropriate turbos (newer Garret GT30s for example) there would be a virtually unlimited amount of power available. Whatever you could build the motor to take you could make. And it would still be tractable.
Stockish exhsaust manifolds won't hold you back too much. There is free power to be gained in a properly designed turbo header, but many turbo legends (such as the RB20) make do and do well with an atrociously designed exhaust manifold.
cheers
I take it twin turbos are really the way to go (i.e. no singles) as the disruption of exhaust flow would be even on both sides?
Meggalla, I'm looking for something a bit wacky. :) I know an N/A V8 will still give me huge power, but I love the sound of a turbo (or two) spooling up, and I don't necessarily want to have a huge lumpy idle. :D
I also don't really want something that's going to be impossible to keep in a straight line when it comes on boost, so I'm guessing mild turbos would be the go. As an alternative to supercharging I guess.
What are the implications of using carburetion instead of EFI? more piping and trickier to implement?
Also, if I put a new late model motor in my car, it will then have to comply with emissions regs, is this correct? Is there any way to get around this, except running LPG?
Tex
Rusty,
I don't really want to stick with a Buick motor if I can help it becuase performance parts for Buick engines have to be bought from the US, and as a result will be EXPENSIVE! That is to say, I'd imagine the fact there are parts for Chev motors (everything from internals to dress-up bits) would mean they are a bit cheaper, and the main attraction is they'd be a lot less hassle to source.
My engine bay may be restrictive as it is, so who knows if it's even physically possible to fit the gear in, along with intercoolers etc...
I don't have a power estimate, I suppose somewhere around 500 at the fly would be nice (supposed to have 365 standard), let's say I want something tractable that would be capable of embarrassing a few rice boys. :) Of course, not on road though. Keep in mind the car weighs about 2.1 tonnes. My motto on power though is kind of "the more the merrier", PROVIDING it doesn't become a pain in the arse to drive comfortably. Must run on Synergy 8000, Optimax or equivalent pump fuel.
As far as the drivetrain goes, the Buick Positraction diff is stronger than a Ford 9", and apparently good for around 650hp in standard form, and she's running a pretty fresh TH400 tranny, again reputed to be good for a similar figure. I don't know what condition the diff is in, internally however.
Take a stab at a build cost for such an engine?? 15 grand? I'd try to do as much of the work as possible myself (a scary thought) to save money, but if it's a case of just buying a new Chev motor and bolting the turbo gear on with no internal mods, then maybe it won't be so bad? And what about emissions? I dont' suddenly want to have a car that need to comply with all the regs - there's not much room under the floorpan for mufflers etc.
Tex
Perhaps some sort of two-stage boost system would be worth implementing to ensure it remains placid on-road?
Tex
Cheers, this is good food for thought...
A 454 may very well be much easier to get a hold of, I don't see many 427s advertised for sale, just picked it for arguments sake as it's close to my original motors displacement.
Maybe a supercharger will be much less hassle... :D
But I want spool-up sound, and a car that won't chew heaps of fuel unless I want it to...
I will have to find someone to talk to about this to get a better idea of what I'm gunna be looking at, my preference would be for as little modification to the internals of the motor as possible! The lower the cost the better, however I am aware of that well-known equation, $$ = hp. :p
Now, does anyone know an engine builder in Sydney who knows their shit where this type of thing is concerned? I wanna do a bit of prelim research...
EDIT: Clarify something for me - If forced induction increases the compression ratio, and hence power produced, why bother de-compressing a motor, just so that it can be re-compressed again by the turbo/supercharger? Or is it much more to do with the fact that the boost pressure is actually FORCING the fuel in, whereas increasing the static compression ratio would not have that effect?
Tex
If you plan on doing it for the power, don't do it, but if you are doing it for the "wow" factor, that's something else again.
$15k spent on a BB would easily get you 700 carburettored hp if you spent wisely.
A mate was on the verge of going TT on his 454 but has decided to go blown instead. To go TT it would almost be mandatory to convert to injection, plus the fabrication costs and turbos etc etc would eat up the $15k in no time.
Cheers howy, at this stage it's just a bit of a fact-finding mission, what these investigations turn up will be what determines the direction I go with the engine. I'm not going for outright hp really, it's kind of to be different, and as I said kind of because I love the sound of a turbo spooling up, and I reckon it would be quite a happy marriage. :)
Keep in mind that if it were confirmed that low boost on a NEW injected 454 would not require internal mods, I could always get the motor installed in the car first, and at a later date decide to add turbos, or work the motor some more... I want to start out with a versatile platform, put it that way.
We'll see what happens... :)
Tex
Rusty,
No arguements from me. Torque rules on the street.
700 streeatable hp is a walk in the park for a stroked BB, plus the added stroke would add even more torque.
I've chatted with Tex since my post and he prefers the TT route. Something interesting and challenging, and a tad out of the ordinary.
But then again, would you expect anything else from Tex?
:D :D :D
LOL @ howy... Touche mate. :D
I'm interested to hear about these setups too howy.. :)
Tex
Rusty,
One HP per cubic inch is only considered ordinary for a street motor, ie a 350cid making 350hp. Most good street motors exceed this by a large margin - by a good 100hp in the case of the 350 example.
There is an article in a magazine i've just bought where a 565 BB makes 1050hp/900lbs on 91 octane standard pump fuel.
Granted, it is an exceptional motor, but it just goes to show what can be done these days.
Edit:
The BB example given makes 1,000hp by 6,000rpm and idles at 900.
blackbart
02-07-02, 09:09 PM
The engine i wanted to start with:
Chev 502 HO Roller Street Thumper
8.2L 450hp stock crate motor
Forged crank and pistons
Roller cam
easy 550hp with head clean up and mild cam
$10,000.:D
meggala
02-07-02, 09:21 PM
thank you bart nuff said.
the mountain motors are awsome and give it some gas and it comes alive
meggala
We better let Tex have his thread back, but i'll sneek a little something in the space below :D
565 cubes
Pro-Filer alum heads - 65cc chambers
470cc intake, 191cc exh
2.450/1.80 valves
Reverse dome pistons circa 11:1 comp
270/285 @ .050 / 0.750 lift solid roller
Wilson 4 bbl intake
1250cfm carb
and LOTS of attention to detail....
Bump up the comp to 15 or 16:1, add race fuel....and the mind boggles...
loser_bob
02-07-02, 11:06 PM
.
XEFalconUte
02-07-02, 11:29 PM
Tex, I think your idea is a hell of a good one. I'm at the moment building a turbo 545 big block ford (385 not FE).
I'm completing the short block build up at the moment the specs are:
dove block (converted to 4 bolt mains with pro-gram caps)
4.5 inch billet stroker crank (with BBC snout size)
oilver rods 6.7'
JE pistons (comp 8.5:1)
(no place to start like a good base)
now I have gotta work out the induction package lol
One thing I have been told is with forced BBC's is that you have to o-ring the combution chamber, doesn't matter how much boost you run.
anyhow something to consider
Simon
VHDREAMS
03-07-02, 07:49 AM
back in the 60's or 70's the Monte Carlo 454 made 455hp, so getting any BB to make hp=cubes shouldnt be a problem,
just get the biggest engine your allowed and go from there...
in NSW a monoconstructed chassis can (in cubes) have the tare weight (kg) X 0.294 N/A, or tare weight X 0.244 turbo'd or supercharged, and if you have a seperate chassis construction its tare weight X 0.333 N/A, or tare weight X 0.286 for turbo'd or supercharged.
and some of those new EFI 454's imported are cheaper than a mild holden 8,
good luck, tell us what u decide on...
I don't know what sort of head work you can get done on the innards of a BB, but if it were me doing it & I wanted the sort of low-down grunt you're after, I'd look at keeping the compression ratio as close to standard as possible, and running low boost. If you keep CR close to standard, then any boost you run gives you extra power; rather than giving more with the boost hand & taking away with the CR hand.
I'll make some numbers up here, just to illustrate; say your CR 10:1 engine makes 400hp standard (n/a). And then say that dropping it to CR 8:1 gives you 320hp (in n/a mode). Well, run half a bar of boost (~7.4psi) in the 10:1 engine & you get ~400x1.5=~600hp; yet do the same calc to get 600hp on the 8:1 engine & it's not far off one bar of boost; 600/320=1.875 bar, or 13psi ... and 13psi is in the "high" range for factory boost applications, whereas 7psi is quite low. And remember that the 10:1 CR car is much less doughy when off-boost; it'll use less fuel too.
So, not knowing 100% the costs & the possibilities, my first investigation would be how to get the head flowing nicely & if I could get the inside of the head shaped a little better so I had some CR margin when running n/a. If that's possible, you can then start putting boost in without worrying so much about detonation; and the higher the CR, the faster the hot exhaust gas is pumped out the rear of the engine, and the faster the turbos are spooled up.
I don't know how much room there is for piping & the like, but a lot of modern cars will take up to 10psi on a standard engine, given an intercooler & possibly even water injection. If you get a computer (or even some aftermarket boost controllers) you can run even higher boost, because it can be programmed to run lower boost in the areas of the rev-range/load-maps that're more prone to pinging.
Note that, as someone else said, this isn't the way to get maximum power. It does give you something that uses no more fuel than an n/a engine which has the same grunt, and it also gives you something nice & driveable & flexible but still with what should be a stunning amount of power.
Thanks for your input people.
XEFalconUte, sounds nice! :)
VHDREAMS, what is tare weight exactly? I believe when the car was weighed for rego when I bought it it tipped the scales at 2.1 tonnes, or close enough to. Using that figure in those calcs, and factoring in that the car has a chassis, I should be able to go up to 600 cubes, which is much bigger than I'd need. Essentially I'm looking for something that doesn't use hideous amounts of fuel, even when off boost. :)
I'll be sure to keep you all posted, as I said this is a fact-finding mission, I don't anticipate making any decisions on this for some time yet.
Forg, I agree with what you're saying, the less that has to be done to the motor internally, the better, as far as cost goes, and I don't want the car to be doughy off boost. The low-boost application sounds best, at least as a starting point. I can always decide later to have more work done I guess, and then up the boost, given the turbos will have a lot of headroom.
I get the feeling piping (especially for an intercooler etc.) could make things very interesting indeed. Although it might solve a problem for me - my bumper is a bit bent, and I don't have much faith in anyone's ability to get it straight again, and looking new. This could be solved by cutting the front out of it, and mounting a fat FMIC in the mid-section (which looks bent from someone running up on to something. Hmmm, I like that solution. :D
Again, if aftermarket management was necessary, I'd look at adding that too, although I'd presume a new Chev motor would come with a Delco computer, and I've heard these are actually quite flexible and tunable.
For a low boost application, standard fuel delivery infrastructure would be maintained, right?
Basically, I'm not looking for outright max power, it's not going to be a drag car (except on Wednesday nights at the creek perhaps :D), and but something with bucketloads of torque and "a stunning amount of power" should be just fine. Considering she already gets up on the plane (:p) nicely when you put the boot in, doubling the power output would be phenomenal. More than double would be even more joyous.
Tex
Originally posted by Tex
For a low boost application, standard fuel delivery infrastructure would be maintained, right?
Even with higher boost, you wouldn't need much to be changed; if you can reprogram the Delco, the biggest changes you'd probably need are a manifold-pressure-sensitive fuel pressure regulator, and beefier injectors (600+hp worth of injectors isn't going to be cheap ...)
Cool. Does anyone know what the emissions issues would be? By changing to a new motor, am I then bound to the emissions regs relevant to that motor? Or can I get around it because my car is pre-emissions anyway?
Tex
Hmm, I reckon 9 out of 10 cops could be fooled with the argument the car is pre-emissions, so the rules don't apply. :)
"No, officer, I had it converted to EFI. Yes, it does look very OEM, doesn't it?!"
I'd prolly say that the rules go with the year the car was built. For example, a new Cobra replica has to comply with new regs, because it has to comply with ADRs. My understanding is that my car is beyond the jurisdiction of the ADRs, because:
a). It's from the US.
b). The ADRs didn't exist in 1969.
Reckon you could argue that the engine is invariably gunna be cleaner than the original motor anyway? :D
Tex
Originally posted by rusty
money in strength (preparation) and wear. lets face it 850Nm at 3500rpm is already 420hp, by 4k its at 480hp, at 5k its 600hp ..
j
Zackerly....my wittle 4L rover makes 800nm@4000rpm (850@4500) on 8psi(IIRC) of boost, and I redline it at a measly 6500rpm... Peak power is at 6000rpm.
A boosted BB should make an awful lot.
My compression is low tho at 7.8:1
Byron
Originally posted by Tex
I get the feeling piping (especially for an intercooler etc.) could make things very interesting indeed. Although it might solve a problem for me - my bumper is a bit bent, and I don't have much faith in anyone's ability to get it straight again, and looking new. This could be solved by cutting the front out of it, and mounting a fat FMIC in the mid-section (which looks bent from someone running up on to something. Hmmm, I like that solution. :D
Tex, would you do the work yourself???
Byron
Originally posted by Forg
II'll make some numbers up here, just to illustrate; say your CR 10:1 engine makes 400hp standard (n/a). And then say that dropping it to CR 8:1 gives you 320hp (in n/a mode). Well, run half a bar of boost (~7.4psi) in the 10:1 engine & you get ~400x1.5=~600hp; yet do the same calc to get 600hp on the 8:1 engine & it's not far off one bar of boost; 600/320=1.875 bar, or 13psi ... and 13psi is in the "high" range for factory boost applications, whereas 7psi is quite low. And remember that the 10:1 CR car is much less doughy when off-boost; it'll use less fuel too.
But don't you end up getting to the same effective CR?. I 10:1 with 7.4 vs 8:1 with 13psi??? I agree that Tex will want it tractable, but lower compression will give more power! but more expense is my guess....My little engine makes 500nm@3000rpm with ~8psi of boost, and thats a chunk of torque, an engine with 2x the capacity should make a lot lot more. Mind you I have tiny turbos so they come on boost way early.
Byron
tex: you need to have a look at Jake's torrie, carb'd single turbo 308.6CI ~1100 BHP on avgas..
you do realise of course that its mega-dollars (comparitively) when a rebuilt high-comp 454 on gas would be cheap to run, and go like a cut cat...
Billzilla
03-07-02, 07:09 PM
You're all a bunch of wussy girls.
Wot you need is a Garret TPE-331-11UA from a Metro 3 aeroplane.
They make 1,000hp at 2,000rpm, and over 2300ft-lbs of torque at the same revs.
Just pop a truck gearbox in backwards to get the fnal drive ratios right and you're laughing.
They suck about 400 litres per hour at full throttle, and are light enough so that a strong bloke can pick one up.
M'kay, it's a crazy idea and I'll shut-up right about now ... :)
Originally posted by biteme
But don't you end up getting to the same effective CR?. I 10:1 with 7.4 vs 8:1 with 13psi???
Yes, but an engine that big doesn't need to be on boost all the time; when you're not, a higher CR gives you better throttle response & better fuel economy.
OK, maybe with a BB fuel economy is irrelevant ... :)
Bill: okay, so why dont you have one in that single seat thing you were building?
and where can i get one? obviously if you are bringing it up i can get one for under 15K? :)
biteme, I probably won't be doing much of the work myself. I'm not trained in anything that would enable me to do it, but if there were things I could do myself that would save me lots of money I guess I'd consider it.
Rusty, those heads look verrrrry tasty. And also very costly! :eek:
GSRman, who's Jake? I do realise that this idea is big bucks, but as I said, I like it! :D
Tex
Jakes performance... 2nd forced induced small block in HP hero's carb'd torrie, yellow, hangs out through the bonnet :)
built most of YES20B
Originally posted by GSRman
Jakes performance... 2nd forced induced small block in HP hero's carb'd torrie, yellow, hangs out through the bonnet :)
built most of YES20B
http://www.fullboost.com.au/racing/dragmeets/2002/turbo_titles_02_06/tt02_014b.jpg
am i the only one that just had their underwear fly across the room?
Hmm, it's orright, but it's a Torana. Kinda cheapens it. :D
What's the background of that car? I imagine with that whopping front mount he's running ginormous boost?
Tube chassis?
Tex
its in an issue or 2 ago of zoom..
not HUGE boost, but not low either :)
nope, its got a 9" diff, no tubbs, or anything like that though..
ran low 9's at the turbo titles..
Is there anything you think I'd be able to do myself on this job that would be worthwhile?
Tex
All the stuff I've done on my car has been "pull it off, replace clean or reco, put it back on", like suspension etc. In fact, it's even getting a bit annoying that I can't fabricate metal brackets for even minor under-bonnet stuff like the ignition module.
As a result ... I'm assuming you've got similar ability to do stuff as me (I've just got a collection of tools, no welding gear), and that would mean you're not doing all that much yourself. Mind you, there're definitely some dollars to be saved by measuring-up, getting others to do things at their workshops, and fitting the pieces yourself; depends on what needs to be done. (eg. you could probably install a lot of the EFI fuel-supply stuff).
Hmm, ok, we have a fairly good collection of tools, Dad is a toolmaker by trade so he's a whizz at whipping all sorts of stuff up. :) We have an arc welder too so as long as we're wanting to weld thicker stuff we can whip up brackets and the like.
Possibly looking at getting a lathe soon, because they're bloody handy, we have a bench drill, grinder, etc.
But no MIG/TIG welding equipment or anything like that.
Tex
I liked GSRmans idea of flipping the headers of the mud-basher's 302 (or was it 351) upside-down and having the outlets of the headers facing forwards.
Could you do this on a 454 Chev for easy & cheap twin turbo placement? Then it would be a matter of making up adaptors to fit some turbos on, and getting an intercooler with dual inlets at the bottom on either side, and a single centrally place outlet to go straight into a throttle body or carb hat - the intercooler piping should be fairly simple on a setup like this (if space confines aren't too tricky.)
I've been fantasizing recently about doing this to a 351 XA/XB coupe and turning it into an auto torque monster cruise machine.
Went to the All Chrysler day on Sunday, and there was a Regal with a wee 273ci V8 and turbo setup. It had a pipe going underneath the block from one header to meet up with the other header outlet and the turbo. Single turbo on a V8 looks like waaaay to much pipework. But hey, it was a good cheap and cheerful DIY turbo setup - had a truck turbo and a carb, and it was doing 13.7s. Intercooler piping on it looked far from perfect, but hey I havn't done it before so I can't criticise.
Cheers,
Adrian
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