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D2K
Dodge Dakota
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6/13/2002
20:28:20
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 Subject: 4.7 Turbo Compressor Choice? Duner? Tom?
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This is mainly for Duner who's the only dude on the net to turbocharge the 4.7...
Duner, may I ask why you chose the TB04? And I think I saw in some past posts you chose the V-1/V-2 trim?
I ask because my plots of PR & cfm (lbs/min) are well right on the TBO4 compressor maps... indicating very low efficency... between 40%-50%.
My baseline numbers come from a 6000rpm redline, 85% volumetric efficiency, 287cid yeilding a max of 433.5 cfm (29.2 lbs/min) of normal flow. And, 10 lbs of boost yields a pressure ratio of 1.68, multiplied by normal flow of 433.5cfm equals 711.6 cfm (49 lbs/min) of flow under the full 10 lbs of boost. So I've been plotting 711cfm at 1.68 PR, and find that the T60 series turbos appear to be more efficient for our motors. Specifically the T61 and 62-1 look appealing.
Was lag your main concern? And if so, wouldn't a lowish A/R on the compressor help out these these bigger turbos?
I certainly appreciate your insight.
regards,
Chris
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Duner
Dodge Dakota
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6/13/2002
21:41:45
|  Turbo Knowledge.......
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Hi Chris,
It appears as though you have much more turbo knowledge than I do. I don't know any of the math that relates to compressor or turbine sizing..... or even how to read a turbo map. But I'm learning more about it every day! This is the first turbo I have ever owned and played with. I simply walked into my local turbo shop (that was highly recommended by my turbo buddies) and told him what I was doing. He asked me about displacement, how much hp I had currently, what rpm range I revved the engine to and how much hp I hoped to get from the whole system. After I answered those questions, the guy walked to the back of his warehouse and came back with a shiny new turbo. So far I've been very happy with his selection.
A larger compressor could quite possibly make more efficient boost. I'm not exactly clear on what more efficient boost means in terms of usage. (Same boost with less heat?) Since this is my normal ride and not really a "race" truck, it generally sees between 5 and 7 lbs of boost normally. I only crank it up at the track and when I've got good fuel in it. To be honest, I'm afraid to make much more than the 14 lbs I've already seen. Since I was making nearly 300 hp before adding the turbo, that 14 lbs is theoretically doubling that number. That's as far out on a limb as I'm willing to go with the stock internals.
As far as the turbine - since I use this as a work truck and tow trailers with it on occasion, I'm quite happy with the .96 A/R I have right now. I have enough trouble keeping it out of boost when towing. A lower A/R would probably let it get into boost all the time... which probably wouldn't be a good thing. At this point I have almost no lag other than the normal bottom end torque feel of the 4.7..... which comes in very strongly between 2500 -3000 rpm.
I would certainly love to try a different turbo with a larger compressor and then a lower A/R turbine....... but not bad enough to buy a new one - or at least not just yet?
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CW
GenIII
6/13/2002
23:07:41
|  RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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Wouldn't a smaller A/R ratio have more exhaust back pressure? Personaly from the turbo calculators I have found online I would probably go with a 1.15 or 1.32.
2001 4.7HO RC 5sp 3.92 LSD
Click on thumbnail for mods.
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D2K
Dodge Dakota
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6/13/2002
23:25:41
| RE: Turbo Knowledge
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Thanks, Duner. You're right. Efficiency=less heat=less back pressure=less chance of reversion and subsequent detonation. It also means less heat going into the intake charge. I'd love to listen the turboshop guy's theory for selecting the T04 or perhaps why its a better choice over some of the 60 series turbos. In the end, I suppose it boils down to application...
If you haven't done so, you've got to get Corky's and Hugh's books on the subject. Corky's book lays it all out for the layman. Hugh's book (a bit dated but still accurate) goes more into the theory and the math. Never thought I'd have use for that one physics course... LOL helps somewhat.
I saw in a much earlier post that you occassionally had traction problems when its wet or raining... especially when towing. May I suggest a higher A/R? Then your boost wouldn't come on so hard or sudden. Your .96 A/R is a "medium" range application BUT hits just as the torque band does too-- great for getting off the line quick, but can get tricky to modulate in low traction conditions... I daresay, it would be misserable here in NE during the winter. :-)
An higher A/R would make towing much easier, and "ramp up" your boost a little more gradual, allowing you to modulate it much easier with the throttle. As I believe you already know, changing the A/R is a fine-tuning adjustment.
Your comment about having trouble keeping it out of hard boost while towing kinda makes sense with my understanding of the subject. Smallish turbos spool up very quickly and come on like a light switch. Bang! No boost to near full boost. Larger turbos build slower and later, given the same size engine. Once turbo size is selected, then A/R selection let's one dial in one's boost curve... steep/sudden (low A/R) or gradual/smooth (high A/R).
Wonder if your turboshop buddies would let you play with a 60 series for a week or so, and compare its characteristics with the TB04? Surely they have a rebuilt laying around.
I hope to build a system that will have similar total output, but have that ever-increasing rush of building acceleration to redline. I own a 4X4 Durango and also tow, off-road, and play hard with it in the winter--and its much heavier than your Dak. Those conditions would make an instant-on setup too dangerous or too much of a hassle to control in my opinion. I hope to avoid the instant boost configuration, and end up with something that performs very linear... like a reostat... more pedal, more grunt.
I'm amazed you've been able to get 14lbs of non-intercooled boost considering the 9.3:1 compression ratio of the 4.7. What are you doing with the timing? Anything?
Thanks for the reply
regards,
Chris
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Duner
Dodge Dakota
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6/14/2002
00:04:04
| CBE Racing Equipment......
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I had Corky Bell's book Maximum Boost for a while.... but I've loaned it out recently and want it back! I might have to see if I can find that book by Hughs. The more I can learn about this stuff the better!
I just might go back to the turbo shop and see if I can try a different compressor..... It might be fun just to see what the difference is. Besides, the turbo guy is probably curious to see what I actually did with all the stuff I bought from him.
Except for when I'm towing the trailer - I like the instant boost part! The torque rush is absolutely incredible for just 287 cubes, I really like where it comes on right now. Of course I would love it if it pulled even harder in the upper rpm range, but with a 4200# truck, the midrange torque is probably more important than the top end hp number. Right now the powerband pretty much matches the profile that the engine had before the turbo. It comes on hard at 2500-3000 rpm and pulls hard to past 5500 then starts to taper off. I'm still working off the premise that the more area under the hp or torque curve on the dyno chart the better. I don't think I would like a linear curve if it meant I had to sacrafice some of the power down lower. I hope to dyno this configuration very soon.... or at least before I make any more changes.
The 14 lbs of non-intercooled boost has only been under controlled conditions. It was with everything cool, cool ambient air temps and for short bursts. You certainly could never drive it like that very far under boost and expect to have anything left. As of yet the only control over timing has been the selection of either the stock PCM or my reprogrammed PCM which has much more aggressive ignition timing. The aggressive one ONLY gets used when there's 100+ octane fuel in the tank.
I have finished and installed my air/water intercooler system. I must say it works beyond my expectations! It's definately home built, but that doesn't make it any less effective. I even went so far as to put a sticker on it called "CBE Racing Equipment"..... Crude But Effective! hahaha I've got to get some IAT readings to know exactly how efficient it is, but when the intercooler and TB are both still cold after a pass down the track at 10 lbs of boost- it must be doing SOME good.
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LI Blackdak
Dodge Dakota
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6/14/2002
00:05:55
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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duner, what is ur 0-60??
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Duner
Dodge Dakota
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6/14/2002
00:48:26
| Just a guess......
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You can get some indication of the 0-60 time by the 60' incremental times from a timeslip. Although I haven't done any 0-60 tests on my truck, my best 60' incremental time is in the 1.8 second range. According to the online calculators (http://www.smokemup.com/auto_math/60_foot.php), my truck should be going 45 mph at the 60' mark and that takes 1.8 seconds. I will guess conservatively that with slicks my truck should hit 0-60 in roughly 4-4.5 seconds. With street tires it's probably more like 5.5-6 seconds.
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D
Dodge Dakota
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6/14/2002
02:17:18
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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*shocked*...wish I had the cash for your first 5
units! ! ! !
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Demon Dakota
DakotaEnthusiast
6/14/2002
10:39:34
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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I am absolutely interested in either a turbo or a supercharger. In your honest opinion, what is the best overall option for the 4.7L ? Is the S/C install too difficult? Or does the turbo make enough turbo and torque when you need it like the S/C does? Lots of questions, but things I'd really like to know before I make my final decision.
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Clevite 77
Dodge Dakota
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6/14/2002
11:53:16
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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it seems that there aren't to many s/c's right now for the 4.7L, and the s/c's don't seem to add to many hp for the $$$$
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BigRedDak
Dodge Dakota
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6/14/2002
13:30:46
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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now, correct me if i'm wrong but, wouldn't a supercharger give you boost throughout the range with the lack of spooling? This would be a huge probably on street tires as you would spin them off the line, and through the first two gears or so. With a turbo, it has to spool, and by the time it does so, you already have traction, so the boost is effectively used?? What are the other benefits of a turbo?
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alex
Dodge Dakota
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6/14/2002
14:06:16
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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A portion of the horsepower that the super charger generates is lost because you have to turn the supercharger itself with the motor. A turbo runs off exhaust flow.
The supercharger builds boost throughout the rpm range. You don't see the full boost pressure until the motor is really revving. Duner's turbo 4.7 truck is set up so that the boost hits with all 10 psi at about 2200-2500 rpm. Bam. Then it's pure torque all the way to 6000. WHoosh..... it just shoves you back in the seat.
Also, with a feather foot, you can keep the turbo out of boost and just drive normally without the boost kicking in. You can do this with a super charger, but that belt is always drawing power off the motor.
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shaggyfrog
Dodge Dakota
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6/14/2002
15:06:05
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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what is a round about price diffrence between supercharged and turbo.
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alex
Dodge Dakota
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6/14/2002
15:21:19
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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Superchargers cost about $3700 and turbo kits cost about $4500-$5000.
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Demon Dakota
DakotaEnthusiast
6/14/2002
15:55:59
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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There is already a s/c dynoed on a durango. It gave over 90 RWHP, which isn't too bad. I would expect a turbo to easily match that, and exceed it with a larger or a twin setup. Why not have sequentially sized turbos, like the RX-7s did? Do you think that would work as well?
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shaggyfrog
Dodge Dakota
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6/14/2002
16:05:29
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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are turbos as easy to "bolt on" as superchargers or is there a lot of customization?
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conig
Dodge Dakota
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6/14/2002
16:23:26
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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I really don't think twin turbos or sequentials are worth it, look at most high$$$$$ supras and rx7's they remove the twins/sequential and go with one large turbo. it tends to make more power and generate less heat
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Clevite 77
Dodge Dakota
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6/14/2002
16:39:31
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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I'm familiar with s/c's and turbo's, now I do have a "make ya think" question. if a turbo needs exhaust pressure to turn the propeller, isn't that causing back-pressure, or do you customize your exhaust accordingly?
And would you want a smaller dia exhaust creating more exhaust pressure helping to spin the propeller?
or opposite for better flowing exhaust?
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Demon Dakota
DakotaEnthusiast
6/14/2002
16:57:03
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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Clevite, I guess you purchase the turbo after you've gotten as much done with the N/A aspect of modifications. Intake, headers, exhaust, maybe a computer program or chip, then purchase the turbo for the setup you're running. In other words, customize the turbo to the setup you are currently running.
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xplikt
Dodge Dakota
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6/14/2002
17:37:16
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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"The supercharger builds boost throughout the rpm range."
Yeah, for a contrifugal, but there is also the positive displacement, which is different.
Demon Dakota, the problem with that is stuff like that might not be compatable with your current aftermarket parts. The headers for example, are totally different and you would be either replacing them or doing some welding. The exhaust can also be considerably different. Of course the intake to the TB is different. You would probably have no problem with the intake manifold though, but even that can be matched to more suit a turbo.
The exhaust is soo important in turbos. I have a friend who's replaced his uppie on his WRX, it brought his full boost down to around the mid 2000s. He's going to replace the downpipe soon too, which should proove to be mightly impressive.
I feel pretty partial to turbos, but it's not like S/C do not have their use..
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zagster
Dodge Dakota
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6/14/2002
19:49:43
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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Can anyone out there recommend a good website that has info about turbo tech?
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D2K
Dodge Dakota
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6/14/2002
21:55:05
| RE: Turbo Knowledge
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Duner - It really boils down to one's wishes. If you're happy with the application, then, mission accomplished! You don't need guys like me trying to question you or tell you that you did "this" or "that" wrong... not that I'm trying to do that-- no.
My D weighs 5800-6000 lbs most of the time-- probably about the same as your truck when its pulling your trailer. It takes a lot of force to get it moving, and a lot of force to change its direction, increase speed, or stop it. All of that force/power has to be channeled through the tires to the ground so that it has something to push against. The tires quickly get overwhelmed. Then consider that I'm not willing to give up my M/T tires for better street traction, and I think you can see where I'm trying to go with my application.
I've been living vicariously through your posts over the past months, and would be thrilled to duplicate what you have there. Then, I considered how touchy traction becomes when you add your trailer and realized that my weight means that I would be in that senerio full time. So, I wish to a avoid an early hard boost configuration where I would have to concentrate too much on not breaking the tires loose. Hell, I can do that now too easily. Kinda takes the fun out of having the power if you can't get it to the ground easily. All this is kinda making me lean towards the 60 series turbos. They have more flow capability, but aren't as sensative as the smaller T04s.
Anyway, think about putting a knock sensor on that motor now that you're intercooling... I'd be very curious to see just how high you can get the boost before it starts pinging.
CW- you're right. Smaller A/R=more backpressure which spools the compressor quicker. Go too small on a small or medium compressor and the boost comes on violently with a torquey V8. All those ricer 4 bangers need small A/Rs because the 4s have no low end torque, and turbos make torque, not HP... its all about the torque baby! :-)
Again, thanks for sharing Duner. And do give us a review and overview of your intercooling system!
regards,
Chris
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Bruce P
Dodge Dakota
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6/14/2002
22:13:11
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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I too, Am interested in a turbo for my 4.7L but still am toying with some questions.
Are you driving the turbo with only one bank (4) of the cylinders? Dosent this make the "sizing" calculations a bit tricky?
What PSI of boost are you running?
Fuel pressure?
EGT? (Exhaust Temp)
How does the relitivly high compression ratio of the 4.7L affect this setup? (High compression ratios are often considerd "turbo unfriendly".)
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Duner
Dodge Dakota
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6/14/2002
23:13:18
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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Bruce - The turbo is driven off of both banks of the engine, it's just mounted on one side for packaging. I generally drive it around town with between 5 and 7 lbs of boost on normal pump gas. For trips to the track or when I just feel like having a bunch more performance, I turn it up to 10 lbs or more. I run race gas for those times and usually put the more aggressive PCM in as well. I use a Vortech rising rate FMU that raises the fuel pressure as boost rises. I do not have an EGT gauge, although I admit that one would definately be a good idea. There doesn't appear to be any problems relating to compression. I have pretty much followed the octane vs compression vs boost table in Corky Bell's book to keep me out of trouble. My boost is not adjustable from inside the cab..... that keeps me from tempting fate. Since it takes a concious effort to increase the boost, I make an equal effort to make sure I have good enough fuel onboard before doing so.
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D
Dodge Dakota
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6/15/2002
00:30:58
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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my brother has been warning me of turbo
applications, the under hood temps, etc, and
has told me many times to go with a super
charger setup.
his S-runner runs the stock pulley 6-7lbs of
boost, but in order to run the 11lb pulley, a
$1300 fuel system upgrade is in order.
wouldnt our daks require a fuel system
upgrade with the turbo setup? or does the
returnless fuel system avoid this???
could my stock (plus a few bolt ons) motor
with a 5-7 psi setup and still have a
screaming truck, or would the boost have to
be turned up while at the track to get
respectable times?
my main concern here would be the pinging,
and reliability issue. I dont know much about
anything when it comes to performance, just
the things I pick up from experience, but
wouldnt a completely bolt on Kenne bell setup
be much less complicated, and "safer" than a
turbo setup, in the long run, considering most
of us, if not all of us use these trucks as daily
drivers? believe me, I would want nothing
more than to woop on some mustang at the
track, with a screamin turbo like duners, but
for us non mehancically inclined people,
which one is the wiser choice...supercharged
or turbocharged?
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Bruce P
Dodge Dakota
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6/15/2002
19:31:26
| RE: 4.7 Turbo Compressor Choice? Duner? Tom?
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Thanks for the details Duner.
I am assuming that you had custom exhaust manifolds welded up to be able to bolt up to the turbine. I'll bet that is NOT available at NAPA ;-)
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