-------- Original Message --------
Subject: Re: Turbo's
Date: Fri, 08 Oct 1999 09:55:36 -0400
From: dahlgren <dahlgren@uconect.net>
To: "Lawrence E. & Cathy R. Mayfield" <lemay@hiwaay.net>
References: <3.0.1.16.19991008074543.2e8fd196@hiwaay.net>
Doc, I have a few questions for you.. How do you run at 14.0/1 air fuel
with 15 lbs of boost? Please tell me you will make us both very rich and
famous..
#2 You seem to have an engine with no cylinder heads on it or the VE of
the engine is textbook perfect..Can Brodix and others close up shop
now..You imply that engine that the turbos are connected to have little
to do with what is going on here.. An example an extreme one but good to
test the theory..Lets pick two engines I am familiar with small ones so
bear with me.. Engine 1 2.65 liters engine 2 2.8 liters both run 16 lbs
of boost..Engine 1 is a Cosworth DFX makes in the range of 900 Hp
engine 2 a GM 60 deg V-6 makes about 400....So there is a lot more than
cubic inches and theoretical air flow..
The best way to find out what you might expect is to first model the
engine as a naturally aspirated engine with a VE that is realistic,use a
bsfc that makes sense for the compression ratio and the run the
simulation at sea level.. now you know the lbs/hr of air the CFM the
engine can pump.. Add the turbo correct for efficiency add the
intercooler correct again change a/fuel ratio to something realistic for
a turbo engine and finally use a bsfc for a turbo engine..now you have a
chance of coming close to what might happen as long as the turbine
housing is sized right and the back pressure is within reason.. This is
a very complicated subject at best...
Sorry if this sounds like a flame or diatribe meant to illuminate not
derogate.... Oversimplification of a complex thing can and will lead to
some pretty disappointing events..
Dave Dahlgren
"Lawrence E. & Cathy R. Mayfield" wrote:
>
> John, and any others interested. The Doctor is in.
>
> First thing is to know jow much horsepower you want or need to make. Fo me,
> I used programs I wrote myself specifically for my car. I used aerodynamic
> drag, rolling resistance and mechanical losses to determine how much horse
> power I needed to accomplish my speed goals. I did this for seeveral
> different altitudes with differing air temperatures and humidities. My goal
> is to have a car which will run better than 200 mph, any more than that is
> gravy for me. I determined that I needed about 600+ hp at the worst case.
>
> Now having the horsepower needed, I can figure the amount of fuel needed to
> meet that need. For me, 600 hp requires 330 lbs/hr of fuel. To get into
> lbs/min divide by 60 and get 5.5 lbs /min.
>
> To burn 5.5 lbs/min at a stoichmetric ratio multiply this by 14.1 for
> lbs/min of air. Ok, this is 77.6 lbs/min of air.
>
> Now find a compressor map! This is key and if you don't have it, you are
> done. But in my case, I have maps for T3, T4, ect that I got off the net.
> So you look at the map which is in lb/min and you see that the map has rpm,
> efficiencies, a surge limit and pressure ratios. If you have a map in cfm
> instaed of mass, then divide the lb/min by 0.07 to get cfm. A std T3 puts
> out only a maximum of about 35 lbm/min. In my case to use T3 std units then
> I have to run 2, actually I need 2.2 turbos, but rounding down = 2 or twin
> turbos. Because I am at the extreme limit of the T3s I will thrash the air
> pretty hard. Anyway, draw a line up from your air mass needs to intersect
> the map. Try to find a map that lets you meet the air mass requirement with
> the highest efficiency and lowest pressure ratio. I want to run about 15
> psi so this is a ratio of 2. I go accross the map until it intersects the
> air mass needs and see if it is within the map's efficiency island. In my
> case, the efficiency is way down which means that I will heat the air in
> compressing it because it takes a lot of rpms to develop the pressure. It
> means that when my car is checked out that I will need to upgrade to a
> hybrid T3/T4 unit which has a T3 turbine wheel and a T4 compressor whell
> and scroll housing and back plate.
>
> This is how I got to twin turbos. And I figured it another way: the stock
> T3 will support about 350 hp in a 2.3L four cylinder so two of them will
> work on a motor of approximately twice the displacement. This makes a
> pretty good check.
>
> As to your question, you might figure something like this. Hmmmm a 5.9L
> diesel turns at 3000 rpm so it ought to support a smaller motor turning at
> higher speed. I am not much on diesels but as I understand it they are
> essentially two strokes and so fire on each stroke. If not then what
> follows needs to be factored by two upwards. So a 5.9L turbo running at
> 3000 rpm should support a 5.9L 4 stroke at 6000 rpm. But it really depends
> on the compressor map. So If you cannot get one for that specific turbo,
> I'sd say you are maybe wasting your time.
>
> I would suggest you try to find the turbo maps and look at T3 Super 60s
> from Buick vehicles. Remember they turbo their Buick Grand National V6
> (3.8L) so two of them should handle just about anything you asked for.
> These however do not have the integral waste gates so you have to install
> something.
>
> Thats another reason I used the T-bird T3s, built in waste gate and actuator.
>
> If your air mass requirement become so high at the upper rpm limits of your
> motor, then build horsepower at a lower rpm and gear accordingly. I built a
> horsepower/torque curve for my motor and then used the different drag codes
> to determine what geaing would be best for my motor combination.
>
> The Doctor has left the building.
>
> mayf
> At 07:07 PM 10/7/99 -0400, John Beckett wrote:
> > Mayf
> >
> > Being a newbe to turbo's...I've got lots of questions. I like the idea
> >of using junk yard turbo's, but I was under the impression that any given
> >turbo will only flow just so much air and therefor a maximum amount of HP.
> >So I guess 325 HP out of a T03 sounds like a lot. Are there modifications
> >that will increase HP numbers? How would one figure the potential HP from
> >say a Cummins 5.9 diesel turbo?
> >
> > I have also heard about Trick Flow valve guide problems...only on Chevy
> >heads...but maybe the Fords are the same. Just bad guide material?
> >
> > John
> >
> >-----Original Message-----
> >From: Lawrence E. & Cathy R. Mayfield <lemay@hiwaay.net>
> >To: John Beckett <johnbeck@blueridge.cc.nc.us>; Lawrence E. & Cathy R.
> >Mayfield <lemay@hiwaay.net>; land-speed@autox.team.net
> ><land-speed@autox.team.net>
> >Date: Thursday, October 07, 1999 4:27 PM
> >Subject: Re: Net Quietness
> >
> >
> >>John, I am using two T03 units from 85 T-bird. I have done enough
> >>calculations that show at a pressure ratio of 2 (1 atmosphere boost) these
> >>will suffice to about 6500 rpm and at B'ville altitude. With the chosen
> >>cam 226/210 ls 110 and compression at 8.5 all may calcs say about 650 hp.
> >>Will be using World Products Senior Al heads (maybe trick flow but I hear
> >>they have valve guide problems). I will have one TB hooked up and One MAF
> >>but running large injectors > 55lbs/hr. Planning on SpeedBrain for ECU so
> >>will have complete data logging and mod capability. As to wheels, no I do
> >>not want steel wheels, I want alloy. I plan on Weld Prostars for racing but
> >>I need a couple of ?? just to put it on the ground so I can roll it around
> >>better.
> >>
> >>mayf
> >>
> >>At 10:03 AM 10/7/99 -0400, John Beckett wrote:
> >>>Wow, that got em stirred up. Might look into NASCAR type wheels for your
> >>>project. I believe they make them with the proper bolt patern, diameter
> >and
> >>>back spacing. What type and size turbos are you using on your Alpine?
> >>>
> >>>At 04:10 PM 10/6/99, Lawrence E. & Cathy R. Mayfield wrote:
> >>>>Too darn quiet on the list! What's going on? Everybody mad at each other?
> >>>>Or what? Did my first TIG aluminum welding yesterday. What a hoot! Looked
> >>>>like a bunch of angry chickens drizzled all over it. But today, a
> >different
> >>>>story! I cranked the amps up, polished the weld area with a scuff pad and
> >>>>went at it. Most welds pretty good (oh, I am making my own twin throttle
> >>>>body upper manifold for my twin turbo setup). I mean it looks homemade
> >but
> >>>>not too bad.
> >>>>
> >>>>I need some wheels for my car. I need something 10 inches wide with 5 on
> >>>>4.5 stud spacing and 6 inch (5.5 ok) backspacing. These are just to get
> >the
> >>>>car on some rear tires so I can determine the shock mounting height, etc.
> >>>>It's already on the front tires. Anybody on the list have anything they
> >>>>might part with? Oh, they need to have the 11/16 stud holes, not tapered
> >>>>nuts, because I am using Mark Williams 5/8 inch studs (HUGE).
> >>>>
> >>>>Well, this otta be nuf to start some conversation...especially my welding
> >>>>expertise.
> >>>>
> >>>>mayf
> >>>>
> >>>>
> >>>>
> >>>>L.E. Mayfield
> >>>>124 Maximillion Drive
> >>>>Madison, Al. 35758-8171
> >>>>1-256-837-1051
> >>>>
> >>>>http://www.hsv.tis.net/~mayfield
> >>>>
> >>>>DrMayf@AOL.com
> >>>>lemay@hiwaay.net <<<<preferred
> >>>>
> >>>>
> >>>>Bonneville Land Speed Racer, '66 Hydroplane Drag Boat (390 FE)
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>
> >>
> >>
> >>L.E. Mayfield
> >>124 Maximillion Drive
> >>Madison, Al. 35758-8171
> >>1-256-837-1051
> >>
> >>http://www.hsv.tis.net/~mayfield
> >>
> >>DrMayf@AOL.com
> >>lemay@hiwaay.net <<<<preferred
> >>
> >>
> >>Bonneville Land Speed Racer, '66 Hydroplane Drag Boat (390 FE)
> >
> >
> >
> >
> >
>
> L.E. Mayfield
> 124 Maximillion Drive
> Madison, Al. 35758-8171
> 1-256-837-1051
>
> http://www.hsv.tis.net/~mayfield
>
> DrMayf@AOL.com
> lemay@hiwaay.net <<<<preferred
>
> Bonneville Land Speed Racer, '66 Hydroplane Drag Boat (390 FE)
|