ok, after much research I think I may go to a twin turbo setup. I have looked into many 5.0 mustang forums, and two 2.2L chrysler turbos, or two 2.3L ford turbos work well for a 302 ci engine. I will run each turbo off its own exhaust manifold, and then have the air tubes join just before the throttle body. So, I've been doing a lot of sketching and think I may either go for one turbo under the drivers side vent and one under the trunk, or both under the trunk. I'm gonna pick up a turbo from the wrecking yard to use for placement issues. I plan on a 5 psi boost with a FMU and adjustable wastegates for now.
Anyone have any problems with this setup?
I'll see if I can get some pictures up soon.
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03:38 PM
PFF
System Bot
smokinjoefission Member
Posts: 138 From: Vancouver, BC, Canada Registered: Jan 2004
The closer the turbo is to the exhaust ports the more efficient it will be. Wrapping exhaust headers before the turbo will keep the heat longer (turbos run from exhaust heat, not exhaust flow).
It's gonna be a major plumbing headache but will look awesome when it's done. Be sure to post pics!
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03:53 PM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
If I were you I will stick with a good single turbo setup, with twin turbo you have dubled your expense. Twoturbos, two down pipes, two waste gates, two oil feed lines, two oil return lines bla,bla,bla. With what we are trying to accomplish with the Fiero's, it is just waste of time and money. My twinturbo TA was a single turbo setup before, now after so much time and money the car maybe .4 to .5 faster . We are talking about a possible low 10sec car.Spend the money else where like a good fuel/timing management ( FAST or Big Stuff 3 or DFI.)
Just my $.02 Good luck Prasad
------------------ "Turbo Cars are like hot women. A little edgy, every guy wants one, some guys can't handle them, and if you throw a little alchohol in the mix they'll rock your world" 1986 GT (waiting for Buick GN setup trasplant) 1984SE 5 Speed W/SBC V8 1987 Buick GN(10.70@124MPH) 1987 Trans Am SBC 355cid Twin Turbo(no track times yet) 1992 GMC Typhoon(13.20@ 99mph) Other cars; JaguarXJ6 & Mercedes AMG 500SEC
[This message has been edited by WikedV6 (edited 01-16-2004).]
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04:37 PM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
the single turbo is the problem. There really arent any that fit the 4.9 well. The closest is the 4.3L syclone turbo and they are very expensive and hard to find. I am planning on using junkyard turbos, and if they need it I will rebuild them. the turbos I'm talking about are very common, and can be had for $75 each. All the piping will be custom and therefore I will have to buy bulk pieces of pipe. I cant see this costing more than $600. The FMU is about $100. I'm not sure if I will water cool or not.
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04:47 PM
PBJ Member
Posts: 4167 From: London, On., Canada Registered: Jan 2001
How about a 300zx turbo or GN. Either of them would do the trick as well. There are also diesel turbo's out there too. Since you are only talking about 5 psi. The twin turbo idea sounds cool but as mentioned above time and money better spent on engine management, cam, roller rockers, coil, wires... Either way I am excited to see what you do.
Pete
------------------
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05:21 PM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
hi PBJ, I consider you the godfather of the 4.9L turbo. I was really thinking about the 300zx turbo for a long time, but it is 1.9L's small. I can't be sure it will supply the CFM I need. I could not find compressor maps for it. anyway. From my research, the best fit was a T76 turbo. It had approx. a 70% efficiency for this motor. But they are expensive ($750 +) Then I looked at a supercharger, and I found one that would work perfect. The Paxton 1000 RR. The RR = reverse rotation. Since I relocated my battery up front, I have the whole passengers side vent area open. This would be perfect for these centrifugal superchargers. But, again these cost way to much for me. $1550 for a new one. These are very hard to find used, but it looks like the 96-2000 mustang kits they sell also include a 1000 RR charger. Most of their kits include the normal rotation type. I considered diesel turbos, but with the problem you had with controlling the boost level, I steered away from them. Also I couldnt put the 6.5 where you have yourse since I have a 4 spd, and all the shifter bracketry are in the way. I'm still thinking about this idea, and I will decide how to go once I pickup a 2.2L turbo next week.
Are you just using a FMU to control your fuel right now?
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06:13 PM
PBJ Member
Posts: 4167 From: London, On., Canada Registered: Jan 2001
Right now we are using a 730 ecm with knock sensor and custom Rockcrawl PROM. MSD 6BTM with adjustable timming retard under boost, with some experimental water injection. Engine was stock internals, stock fuel injectors, stock pressure regulator, stock ignition, stock fiero V6 fuel pump. Waste gate is controlled by a chrysler 2.2 mechanical actuator. It was recommended to me to decrease the waste gate port size to better handle boost pressures, but I will now have less restrictions after the turbo that were "backing up" the system creating huge challenges to keep boost under control.
Pete
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06:37 PM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
There is nothing wrong with using a large desil turbo. With the 4.9 there isn't much to worry about turbo lag, there is already tons of torque down low. By the time you hit 3-4k rpms you will be at full boost and the engine won't fall on its face past 4500rpms.
Twin turbo only sounds cool but its a complex setup, like others said, spend the extra money on a cam.
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07:15 PM
PBJ Member
Posts: 4167 From: London, On., Canada Registered: Jan 2001
One other thing to consider is with twin turbos you'll have dual exhausts. Which means either dual O2 sensors (and all that entails) or a two into one exhaust at some point.
Also, there's not much room in that bay for one turbo, much less two. A friend of mine has a 302 mustang with twin turbos and he had to cut away quite a bit of his engine compartment to get them to fit along with his intercooler (which by the way is something you should probably consider with twin turbos). As someone else pointed out, the turbo should be as close to the exhaust manifolds as you can get them. If you're using a manual tranny the shifter cables really take up a lot of space too.
Just some ideas, I'd love to see you pull it off and lay waste to the Rustangs.
How about a 300zx turbo or GN. Either of them would do the trick as well. There are also diesel turbo's out there too. Since you are only talking about 5 psi. The twin turbo idea sounds cool but as mentioned above time and money better spent on engine management, cam, roller rockers, coil, wires... Either way I am excited to see what you do.
Pete
Pete, I was under the impression that most turbochargers for diesel engines aren't suitable for gasoline engines. The oil seals in a diesel turbo aren't made to experience vacuum from the manifold.
I have never taken one apart to see if it has oil seals within. But I believe it does because I blew the seals on my first. We dollied the car down to PA (9 hr trip) backwards and I did not know to plug the exhaust to keep air from blowing through the engine (open valves) thus spinning the turbo with no lubricant and it burnt oil like crazy. I swapped that turbo out and no more oil burning. Also the vacuum the engine produces is after the throttle plate. The turbo is before the throttle plate, so if there is any measureable vacuum there it because of a bad airfilter. So IMO that statement from the link can not be true. Maybe its true in the old days? Our turbo is out of a 1998 K truck and emissions would not allow oil burning of any kind-thus seals in diesel turbos??????
Concerning that trucker's recommendations - That was true of the old style compressors but I "think" emisssions regs won't allow them to not use seals due to oil burn off. Also, he is referring to the older carburator engines w/ the carb in front of the turbo (draft through the carb). They did this because only special or converted carbs could be pressurized and deliver fuel. But getting back to what Pete was referring to, I believe all modern turbos have oil seals in them today so that should give you more options.
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09:21 AM
Will Member
Posts: 14216 From: Where you least expect me Registered: Jun 2000
Yeah, the oil seal thing is only an issue with draw-through carbeureted setups.
What's the redline of the 6.5? Roughly, CFM = 0.5*displacement*max RPM
What's the redline of the VG30DET? If it spins to 7,000 RPM it might still be a good candidate
------------------ '87 Fiero GT: Northstar, Getrag, TGP wheels, rear sway bar, rod end links, bushings, etc. '90 Pontiac 6000 SE AWD: Leaking ABS unit fixed, load levelling rear suspension fixed, still slow
[This message has been edited by Will (edited 01-17-2004).]
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11:28 AM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
I am not into turbos so would you care to explain that statement. It doesn't make sense to me.
------------------
Red 88 GT T-Top 3800 INTERCOOLED SUPERCHARGED White 88 GT Stock Please give me a rating if you appreciate my contribution. History of Skitimes Car UPDATED 8-11-03
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01:48 PM
PBJ Member
Posts: 4167 From: London, On., Canada Registered: Jan 2001
I will not get technical here at all but. In order to get boost you must try pushing more air into the engine than is coming out. So if you spin a fan on the air comming out, driving another fan on the air going in you will get no "boost" just two fans spinning in the same amount of air going in as comming out. If you add alot of heat to the one side (exhaust) you get rapidly expanding air/gas that is where the "benifit" comes in. I know this is a very simple explanation but it worked for me at one time.
and a 6.5 is 400 ci that redlines at 3500 rpm.
Pete
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02:13 PM
PFF
System Bot
bushroot Member
Posts: 496 From: Grand Rapids, MI, USA Registered: Jan 2003
Yeah, the oil seal thing is only an issue with draw-through carbeureted setups.
What's the redline of the 6.5? Roughly, CFM = 0.5*displacement*max RPM
What's the redline of the VG30DET? If it spins to 7,000 RPM it might still be a good candidate
Sorry... displacement has to be in cubic feet for this to work. I thought the units would be self-explanatory. Nevermind.
cubic inches/1728 = cubic feet.
Or do what bushroot did.
------------------ '87 Fiero GT: Northstar, Getrag, TGP wheels, rear sway bar, rod end links, bushings, etc. '90 Pontiac 6000 SE AWD: Leaking ABS unit fixed, load levelling rear suspension fixed, still slow
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08:22 PM
The_Raven Member
Posts: 203 From: Brantford Ontario Registered: Aug 2003
Turbos don't run solely on exhaust heat, but also flow, this is why most turbo headers or systems use "small" diameter tube/pipe before the turbo, it raises velocity, which also helps keep heat in teh exhaust gases, both heat and flow work together to spool the turbo(s)
------------------ The Raven :Under Construction "James" 1985 GMC Jimmy, 3.2L turbocharged intercooled hybrid 13.873 @ 99.08
"Speed Costs, How fast do you want to go?"
[This message has been edited by The_Raven (edited 01-17-2004).]
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09:04 PM
GTFiero1 Member
Posts: 6508 From: Camden County NJ Registered: Sep 2001
why bother running a twin set-up when its only going to be 5psi where a single turbo would be more efficient and less costly?
Are you sure it would be more efficient? It takes longer to spool a larger turbo, two smaller ones would give him almost immediate spool. It takes some time looking at compressor maps to determine what's the best turbo(s) for a particular application. A lot of people (Supra, DSM, RX-7, etc) who run large turbochargers, size them for top end performance. They'll often use nitrous off the line to spool it because it hasn't been sized for drivability. It's been sized for massive amounts of boost and no regard for lag. Sizing a turbocharger based on the pressure you want to produce isn't the proper way to do it. You have to take into consideration a couple more factors, such as the size of the engine and the amount of flow you're going to be able to get through it (there's a few things to that too). I'm not saying you're wrong about one snail or two. I'm just saying that it looks like you made that observation by the seat of your pants without doing the math.
I'm not going to bust out the calculator and compressor maps to see what would be the exact right thing. But as is the 4.9 is putting out 300 ft*lbs toward the bottom of its rev range and running out of breath at the top end. To me it seems you wouldn't want a smaller turbo that reaches boost threshold at 1500 RPM. Instead you would want to hit it more around 3000 to help the top end where the 4.9 is lacking.
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06:59 AM
collinwestphal Member
Posts: 698 From: Waukesha, WI, USA Registered: Jun 2003
thanks for pointing out the fact that the two smaller ones would spool faster than one larger one. Somehow that blew right by me. The reason I looked toward the TT was because I couldnt find any cheaper single turbos that fit well. smaller turbos are very common, and I thought combining two turbos might be worth a thought. thanks for all replies, I'll definately be doing some kind of boost this spring/summer. There isnt much else you can do except for mild boost.
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11:12 AM
bushroot Member
Posts: 496 From: Grand Rapids, MI, USA Registered: Jan 2003
I'm not going to bust out the calculator and compressor maps to see what would be the exact right thing. But as is the 4.9 is putting out 300 ft*lbs toward the bottom of its rev range and running out of breath at the top end. To me it seems you wouldn't want a smaller turbo that reaches boost threshold at 1500 RPM. Instead you would want to hit it more around 3000 to help the top end where the 4.9 is lacking.
If you’re not going to do the math, don’t bother arguing with me about the results. “the way it seems” is often wrong. As an electrical engineer, I can tell you. If you want the correct answer, do the math.
If you’re not going to do the math, don’t bother arguing with me about the results. “the way it seems” is often wrong. As an electrical engineer, I can tell you. If you want the correct answer, do the math.
Would you care to enlighten me as to why he would want to spool his turbo(s) at a low boost threshold? And to what benifit this would give the 4.9 motor?
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02:55 AM
PFF
System Bot
bushroot Member
Posts: 496 From: Grand Rapids, MI, USA Registered: Jan 2003
Are you sure it would be more efficient? It takes longer to spool a larger turbo, two smaller ones would give him almost immediate spool. It takes some time looking at compressor maps to determine what's the best turbo(s) for a particular application. A lot of people (Supra, DSM, RX-7, etc) who run large turbochargers, size them for top end performance. They'll often use nitrous off the line to spool it because it hasn't been sized for drivability. It's been sized for massive amounts of boost and no regard for lag. Sizing a turbocharger based on the pressure you want to produce isn't the proper way to do it. You have to take into consideration a couple more factors, such as the size of the engine and the amount of flow you're going to be able to get through it (there's a few things to that too). I'm not saying you're wrong about one snail or two. I'm just saying that it looks like you made that observation by the seat of your pants without doing the math.
[QUOTE]Originally posted by bushroot:
If you’re not going to do the math, don’t bother arguing with me about the results. “The way it seems” is often wrong. As an electrical engineer, I can tell you. If you want the correct answer, do the math.
First off, if you would be so kind as to read what was posted before firing off your mouth, it would be greatly appreciated. For your convenience, I've posted all the relevant parts above, so that you might try reading them again.
Secondly, it’s obvious where this is going. You’re trying to drag me into a pissing match. You think you know something intuitively, without “busting out the calculator” as you put it. Can you imagine how poorly cars would be built if engineers went on intuition alone?
I never said that two turbochargers would be better than one, I simply showed the possibility. You should be careful when you try to put words into people’s mouths. They often don’t like it.
Since you’ve confronted me, I’ll do the research for your intellectually challenged ass. That’s really what you want anyway isn’t it? Someone to do the work for you?
Let’s start out with compressor sizing:
quote
Originally posted by bushroot:
Theoretical CFM = CID*RPM/3464 Actual CFM = CID*RPM*VE/3464
So, the 4.9 is 300 CI and we want it to rev to 5500 RPM. We’re also going to assume that it can reach 85% VE.
Now, we know that compressed air is warmer. We now have to take into account temperature rise. T2 = T1 (P2 ÷ P1)0.283
T2 = Outlet Temperature °R
T1 = Inlet Temperature °R
°R = °F + 460
P1 = Inlet Pressure Absolute
P2 = Outlet Pressure Absolute
Inlet temperature is say, 70° F and we're going to want 6 psi of boost pressure. To figure T1 in °R, you will do this:
T1 = 70 + 460 = 530°R
P1 will be 14.7 and the P2 6 psi above that. Add the boost pressure to the inlet pressure.
P2 = 14.7 + 6 = 20.7 psi
T1 = 70
P1 = 14.7
P2 = 20.7
The formula will now look like this:
T2 = 530 (20.7 ÷ 14.7)0.283 = 584 °R
subtract 460 to get °F
124 °F outlet temp
This is a temperature rise of 54°F.
Now, let’s say the compressor has an adiabatic efficiency of 70%, which is pretty typical.
Temperature rise ÷ adiabatic efficiency = actual output temperature rise
This tells us that the actual output temperature rise will be 30% higher
54 ÷ 0.7 = 77 °F actual output temperature rise
add the temperature rise to the inlet temperature:
70 + 77 = 147 °F actual outlet temperature
Next is the density ratio. Air becomes less dense as it’s heated.
(inlet °R ÷ outlet °R) × (outlet pressure ÷ inlet pressure) = density ratio
so:
(530 ÷ 584) × (20.7 ÷ 14.7) = 1.28 density ratio
actual inlet flow in in cfm:
outlet cfm × density ratio = actual inlet cfm
404.879 CFM × 1.28 = 518.245 cfm inlet air flow
multiply cfm by 0.069 to convert cfm to lbs/min.
518.245 cfm × 0.069 = 35.76 lbs/min
Now we can look at compressor maps to decide which will work best. You want to be close to the surge limit, in the “meat” of the efficiency. Also, I forgot to mention. When you use 2 turbos, you split the above number in half. If you’re looking for one turbo, you’d use the value of 35.76 lbs/min. For two, 17.88.
For the purists, yes I rounded numbers. I figured the rest of you would roll your eyes if I took things 10 places or so out.
I've been asked to edit out the portion of my post where I make a personal attack. I'm not going to remove it. However, I'd like to state that there was a misunderstanding on my part, as he states that it was not a personal attack on me. For my misunderstanding, I apologise. In any case, it was probably inapropriate for me to lash out the way I did at anyone. Whether they were intending on being malicious towards me or not.
[This message has been edited by bushroot (edited 01-20-2004).]
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03:20 PM
TaurusThug Member
Posts: 4271 From: Simpsonville, SC Registered: Aug 2003
Thanks for crunching the numbers, + for that. No if only some one could find a turbo map calculator for a 6.5 diesel's turbo . Cause I could not find one.
Pete
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10:39 PM
Jan 20th, 2004
bushroot Member
Posts: 496 From: Grand Rapids, MI, USA Registered: Jan 2003
I think 85% is a bit high. Varoius things I've seen and read lead me to estimate 100% VE to be about 85 ftlbs/litre at streetable compression. Do the math for the 4.9, and you get about 66% VE.
------------------ '87 Fiero GT: Low, Sleek, Fast, and Loud '90 Pontiac 6000 SE AWD: None of the Above
Originally posted by bushroot: First off, if you would be so kind as to read what was posted before firing off your mouth, it would be greatly appreciated. For your convenience, I've posted all the relevant parts above, so that you might try reading them again.
Secondly, it’s obvious where this is going. You’re trying to drag me into a pissing match. You think you know something intuitively, without “busting out the calculator” as you put it. Can you imagine how poorly cars would be built if engineers went on intuition alone?
I never said that two turbochargers would be better than one, I simply showed the possibility. You should be careful when you try to put words into people’s mouths. They often don’t like it.
Since you’ve confronted me, I’ll do the research for your intellectually challenged ass. That’s really what you want anyway isn’t it? Someone to do the work for you?
You completely took what I said the wrong way. My first comment wasn't even directed at you. And my second was merely a question.
PM Sent.
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06:52 AM
bushroot Member
Posts: 496 From: Grand Rapids, MI, USA Registered: Jan 2003
I think 85% is a bit high. Varoius things I've seen and read lead me to estimate 100% VE to be about 85 ftlbs/litre at streetable compression. Do the math for the 4.9, and you get about 66% VE.
My mistake. The thing doesn't breathe very well does it?
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08:05 AM
bushroot Member
Posts: 496 From: Grand Rapids, MI, USA Registered: Jan 2003