Moparts
TURBO GUYS! Is there a formula for..
Posted By: valiantboy
TURBO GUYS! Is there a formula for.. - 08/28/09 08:07 PM
for choosing a carb for a turbo app? i know there is math for finding the right turbo. how do you choose the right carb for the app? ill be sticking a turbo in a 318 powered a100 van. not alott. maybe a 70-78mm unit, air-to-water cooler. 18psi max probly. i was thinking maybe 750 - 820cfm. am i off?
Posted By: feets
Re: TURBO GUYS! Is there a formula for.. - 08/28/09 09:35 PM
That's not a bad choice. For years the common word has been to use the same size carb as a N/A engine. I disagree. I felt a HUGE difference between a boost prepped 650 and standard 750 carb.
Go a step or two above your typical carb for that motor and you'll make a bit more power. Drivability may be down a wee bit. That's your call to make based on the type of use the vehicle will see.
Posted By: RoyceFlo73
Re: TURBO GUYS! Is there a formula for.. - 08/29/09 01:28 AM
With 18 psi, i'd call that a bit more than a little. Are you building the motor for the turbo? or are you just going to put a turbo on a stock 318.
Amongst everything else, more than around 6psi you pretty much need to be running forged pistons. Also, with that much boost, the stock N/A cam will be horrible. I built a twin turbo 318 poly, and i can look up what i ran for a cam in it, but i remember it being a very small lift, high over lap. Comp reground one for me.
But, as said above. i would recommend a carb size up from a N/A motor. Also, i had best luck with a single plane manifold.
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 08/29/09 02:49 AM
yeah this will be forged pistons, h beam rods, steel crank and a base comp of about 8.5:1. useing steel magnum heads, cometic gaskets and head studs. not too sure on a cam either. was thinking of the magnum r/t cam or the step up. will be based on a mag block with rollers. just want to be sure. i will have to buy a blow thru carb anyway and dont want to make more than one purchase. them things spencive!
Posted By: RoyceFlo73
Re: TURBO GUYS! Is there a formula for.. - 08/29/09 07:31 AM
I got a good book, and bought a few carbs from a local carb shop and modified on for a blow-through setup. I can get you the title/author of the book, gotta dig it out tomorrow.
Then i took my time and built/modified one. It's a boost actuated secondary setup.
As far as the cam. I sent one down to comp, told them exactly what i had and what i was looking for and they ground one for me. As it runs, i would say they know what they're talking about. Then again, i'm sure you could get a cam meant for a supercharged engine from any of the aftermarket cam companies and they'd all be fine.
18lbs is awesome for a street engine. I run only 14, the twin setup spools quick and the turbos efficiency dumps real bad after around 6200rpm so they lose the boost pressure and pretty much self regulates. I have a big ol' 66 4door fury, and it's pretty ridiculous seeing/hearing a 4door with turbo whine.
Either way, should be a lot of fun to drive, and it sounds like you're building it right.
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 08/29/09 01:40 PM
ive built plent on n/a motors and tuned them. been watchin how wicked turbo motors can be/are and wanted to try me hand at it. just so happens i came upon a 69 a100 window van for $250. i figured this would be a good platform to play with. 18psi i think is alott too. ma onl run 12-15 after the cooler. was going to talk to scott brown too and see what he suggested as far as a cam. id like to build m own blow thru carb.. alott less epencive that way
Posted By: whitemtnelf
Re: TURBO GUYS! Is there a formula for.. - 08/30/09 09:39 PM
you should use a cam with a larger LSA when running turbos - something in the 112-114 range. No sense in blowing your pressure out the exhaust.
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 12:05 AM
also too.. better to run a single or twins? before i didnt think i had room for an intercooler. now i beleive i have my intercooler problem solved and im thinking about twins. i guess its more of a preferance?
Posted By: whitemtnelf
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 01:28 AM
If you're new to turbos then check out this site - turbosbygarrett.com. Like everything else with engine design there are trade offs. With turbos the trade off is between throttle response and top end. It also depends on how much money you want to put into this project. There are plenty of used turbos for 4 cyls and diesels. For a big top end design you could go with both exhausts feeding into the diesel size turbo. For lower boost (max 14psi) and better throttle response you could go with two smaller turbos. There are dozens of possible combinations depending on where you want to go.
Posted By: Wedgeman
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 02:13 AM
Are there any websites on how to build a turbo engine or links to how it works and what you need ?
Dan
Posted By: RoyceFlo73
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 03:43 AM
HPbooks "Turbochargers" by Hugh McInnes for me was one of the hands down best book for turbocharger theory.
It explains everything very very well, and is sectioned off well as to give basic theory and specific applications.
As for a twin-turbo setup, I ran a twin turbo for my 318 because i was able to build boost at very low rpm and I have zero turbo lag. By using two small (garrett T04B's(cant remember if theyre Bs or Es)). Either way, like i stated before, their efficiency drops so low past 6k rpm because they can't handle that volume of air that they start to drop the psi.
Also, for the 318 C.I. at 3800 Rpm, the volume of air being put out is right in the sweet spot of my turbos and they're running at a high 88% efficiency (according to the maps). Which is nice for my big car that just roams the streets and it doesnt make sense to have a Ve (volumetric efficiency) achieved at a higher RPM.
Large turbos are not used to make "more boost". You have to consider where most of your driving will be, and where you want the boost. If you are going to be drag racing it, then a big single turbo that has high Ve at High RPMs makes sense.
Too small a turbo may dump efficiency above a certain volume of air being put out of the engine and although you may spool quickly; it means nothing because you swamped the turbo and it won't be able to deal with it.
I know that even a single garret T04B is a good turbo for the 318s...single or twin setup. It really just depends on exactly what you plan to do with it, and where you want the pressure.
Posted By: kick_the_reverb
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 04:15 AM
It's certainly going to be interesting to see how you plan to package everything in the cramped space of an A-100
Good luck!
Ran
Posted By: CokeBottleKid
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 05:47 AM
Quote:
HPbooks "Turbochargers" by Hugh McInnes for me was one of the hands down best book for turbocharger theory.
It explains everything very very well, and is sectioned off well as to give basic theory and specific applications.
As for a twin-turbo setup, I ran a twin turbo for my 318 because i was able to build boost at very low rpm and I have zero turbo lag. By using two small (garrett T04B's(cant remember if theyre Bs or Es)). Either way, like i stated before, their efficiency drops so low past 6k rpm because they can't handle that volume of air that they start to drop the psi.
Also, for the 318 C.I. at 3800 Rpm, the volume of air being put out is right in the sweet spot of my turbos and they're running at a high 88% efficiency (according to the maps). Which is nice for my big car that just roams the streets and it doesnt make sense to have a Ve (volumetric efficiency) achieved at a higher RPM.
Large turbos are not used to make "more boost". You have to consider where most of your driving will be, and where you want the boost. If you are going to be drag racing it, then a big single turbo that has high Ve at High RPMs makes sense.
Too small a turbo may dump efficiency above a certain volume of air being put out of the engine and although you may spool quickly; it means nothing because you swamped the turbo and it won't be able to deal with it.
I know that even a single garret T04B is a good turbo for the 318s...single or twin setup. It really just depends on exactly what you plan to do with it, and where you want the pressure.
It's air consumed not put out...
Posted By: RoyceFlo73
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 08:14 AM
I was actually referring to my given turbine wheel. Not the compressor wheel. Therefore, it's air put out by the motor and consumed by the turbo.
The air going into the engine has to leave, to spin the turbine and power the compressor. The A/R on my turbine wheel looses efficiency in taking the incoming exhaust and converting it to rotation at around 6000.
A/R on the turbine wheel has a HUGE impact on spooling as so does the Trim of the compressor and turbine wheel. However, housings and A/R are easy enough to change. Regrinding an impeller...not so much.
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 12:47 PM
this is going to end up being a daily driver. im building things for lower rpm use, 6000 and under. if i went with twins was thinking of a pair of t4/t3 hybrids. i will probly max out around 15 psi so they wont be too stressed. that should put theyr efficiency in the 70 - 75% range id hope. also have a low single plane intake thatll hold the carb. dont think runner length will have much say in this setup? also ill be running a water to air cooler with a seperate cooling system. not quite sure how its all gunna fit.. but im gunna try.
Posted By: kick_the_reverb
Re: TURBO GUYS! Is there a formula for.. - 08/31/09 05:14 PM
Fitment wise, I would say you will need to extend the doghouse in the available directions. Just trying to fit the whole thing in a stock doghouse is asking for trouble. Also, you might need some heat extraction blowers to get the trapped hot air out of the doghouse.
Ran
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 03:01 AM
im thinkin more of mounting the turbo/turbos right to the manifold and keeping the aftercooler under the van so most everything will be out of the doghouse. will alread have the msd and btm under the doghouse.
ill have to make some dry runs on fitment after i get the motor/trans in. still not sure if ill use shorty headers or magnum manifolds. itll end up being whichever will save the most room. i didnt know how cramped it was underthere till i got my fingers dirty heh.
another thing: how do these vans do as far as traction? i will be running a pinion snubber, adj shocks and drag radials. will i need anthing else in the line of traction aids? caltracs/slide-a-link or the like? im sure its just like every other car.. trial and error at test n tune.
Posted By: kick_the_reverb
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 05:32 AM
I suggest you keep the MSD stuff inside the van and not inside the doghouse. I installed my Mallory unit and the coil on the back of the doghouse (inside the van), but some people like to hide them on the floor beneath the seat. The doghouse is very cramped and gets very hot.
About traction, I wish I could tell you, I am no where near that stage yet. One thing about Cal Tracks, you have to remember that the springs are over the axle in the van, but i think they make a version for that kind of setup.
What's you brake situation?
Ran
Posted By: RoyceFlo73
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 06:32 AM
Quote:
i will probly max out around 15 psi so they wont be too stressed. that should put theyr efficiency in the 70 - 75% range id hope. also have a low single plane intake thatll hold the carb. dont think runner length will have much say in this setup?
I have no idea about fitting it into an an a100. I have never worked on one at all.
However, you can google most turbo maps or call the manufacturer and request one. This will tell you exactly the efficiency that a given turbo will run while displacing a given amount of boost. All you have to do is figure out the CFM or lbs/min of air that the engine will be using. This is derived by displacement, given RPM / 2 that you want your peak boost at.
Turbos will be listed with a trim and A/R. The A/R doesn't really change the Ve strictly speaking. However, it will change the velocity of the incoming charge and does have an effect on overall boost. It play's a big roll in tuning lag.
The book i listed early, as well as garrett's website can give you a lot of good insight on designing and choosing your turbo system.
That book I know has some interesting ideas that will help you alot with the a100. There is a section on under-chassis mounted turbos. There is some things to consider when doing so due to the amount of volume of air that would be present in the plumbing between the turbo and intake.
However, it really does give ALOT of information and takes many applications into consideration. It's a fairly technical book, I am a physics/math major (5th year senior and going back for mechanical engineering) and a lot of the information i felt was laid out in a very clear scientific and theoretical way, then more specifically.
It gave a good understanding as to how turbos work, not just another stupid book that tells ya to "connect A to B to C and there you have it" 
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 01:46 PM
thanks royce. im def gunna check that book out. soon as i get more $$ lol. work has been reeeeal slow last few months. im doin good to pay bills at this point. hopefully thatll change soon.
ran, thats agood idea about mounting under the seat. theres about as much room there as there is under the doghouse lol. yeah i have to keep remembering the spring thing. was thinking about flipping the 8.75 to over the springs and notching the frame for clearence. i dunno bout that tho. i just dont want the van to sit too high and look funny. well funnier than it already looks lol. as far as brakes im gunna go disks all the way around. ive checked out aajs setup. doesnt look too bad. id like to stick with all mopar stuff ya know? just somthing about shivvy parts on my van..
Posted By: RoyceFlo73
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 03:29 PM
Good luck on the project, PM anytime. A turbo setup does not have to be expensive. The biggest expense is usually building the block up.
The first turbo setup I built cost about 500$. It was ugly and ran only about 6psi. It was after that, that i ripped out the poly and built it for the turbo and more boost. But most of these old engines i think could take at least 6 psi without any issue, just as they are.
Either way, good luck.
Posted By: Rug_Trucker
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 04:52 PM
IMO this application is screaming for a remote turbo!
You'll never need a heater in the Florida winter with them in the dog box!
How's the wife's Cuda coming?
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 06:06 PM
yeah remotes are a good idea too. just pipe to them. sooo many directions and so little $ lol. sold the wifes cuda bout 5yrs ago. ended up getting a 67 barracuda fastback. bracket racer. did the bracket thing for a while. really miss the street car so im sellin the 67 to fund the a100.
Posted By: kick_the_reverb
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 06:19 PM
For disc brakes there are quite a few options...look up posts by me (I don't post that often, so it shouldn't be too hard to find).
One of the two unproven possible solutions that I thought off recently:
AndyF Viper calipers + 11.75" rotors mounted using DrDiff's sleeves, on 10" drum A100 spindles.
Just read in the lastest Mopar Action about a C body kit that E-berg helped Scarebird develop. I suspect that the C-body drum spindles might be very similar to the A100 spindles for 11" brakes. I'll need to ask around, but that is something that might work.
The other options I mentioned in the past have been working on other people's vans. These last two are just my theories...
Don't forget to join the A100 yahoo group. That's where the real bulk of A100 info is.
Ran
Posted By: valiantboy
Re: TURBO GUYS! Is there a formula for.. - 09/01/09 09:32 PM
which yahoo group? theres like 6 i think. ive joined a few and got nothin but sex spams. ive done the math and figure i need 57 lb/min to support 475hp. i think ill have to go twins to get that much air. i wouldnt be able to afford a turbo that size lol. nor would i be able to mount it anywhere.
Posted By: kick_the_reverb
Re: TURBO GUYS! Is there a formula for.. - 09/02/09 05:29 AM