87z28fromhell

I am brainstorming here....I have a 350 laying around and wish to build an e85 turbo engine to go in my camaro possibly. I want a single turbo that spools very quick. My questions are: CR for a boosted e85 engine? Turbo specs? and is this really going to be any more efficient? I know e85 likes higher cr's and higher engine temps. But how high going with boost? I only want around 10-15psi of boost. Is this amount of boost possible at 1500rpms? this engine being a tpi will never see above 5000rpm and even more likely not above 4500rpm. Horsepower is a goal here so long as this engine is as efficient as possible. I will be running dart s/s 165cc heads and a voodoo cam for now. Any and all suggestions will be greatly appreciated. Also planned on 30# injectors.

SpitotRs305

i am no expert on turbocharging or E85 but...

you will need more E85 than gas add that ontop of a turbo with 10-15 psi you would probably want more injector

and with the turbo forcefeeding that tpi you will be seeing 4500+ RPMs
it probably wouldnt be much fun if you didnt

as for CR i would still say you want to keep it low as in 9.0:1
and 10-15 psi at 1500 might be possible but very unlikely if you set it up correctly, plan on maybe 4-7psi

87z28fromhell

figured as much....I am looking for compressor and turbine sizes. I will be keeping the 2.73 gears...Most likely will go with megasquirt for tuning.

SpitotRs305

well to pick the right turbo for your engine you would need to calculate the engines VE for a different rpms then figure out how in the hell to read a compressor map... but i will give you a hand
read this first
http://www.theturboforums.com/smf/in...?topic=38388.0
this is okay dont know how good it is
http://www.turbofast.com.au/TFmatch.html

rob_m

You'll need 1 1/2 X the fuel theoretically on e-85, There are alot of posts on turbomustangs dot com, some would indicate that you can get away w/ just 35% more fuel, I'd go there and do a search. Most people w/ FI cars on pump gas run pig rich and pull lots of timing because pump gasoline is such garbage. E-85 OTOH is 100+++ octane and burns really cool. From what I've read, you don't need to richen a boosted engine up as much as theoretical for e-85. I'd say you'd be in the neighborhood of 8:1.

That said, 30's wouldn't support much HP. 30's at 90% duty cycle are only 216 lbs/hr of fuel, or 3.6lbs/minute. At 8:1 that's only 28.8 Lbs of air a minute. You're going to need MUCH bigger injectors.

PS You don't even want full boost at 1500 you tires would be obliterated

junkcltr

iTrader: (1)

For the 1500rpm and 10+ PSI and higher RPM boost without choking you need a sequential setup. The 30#s will do the job for a bit. Then the MS-II or MS-I will need to turn on the exta 83#/hrs.

For the turbo, you need one big one and one small one for the boost vs. RPMs you desire. Once you read up more about turbos you will realize that your goals are probably totally unrealistic in terms of your design and fab skills. Start slow and do something realistic like most people do. The setup you want is exotic.

TurboedTPI

Is it an auto or manual? Cause an auto car will never see 1500rpm if your wide open. With even a stock converter. And your TPI will rev a little higher with some boost. Mine pulls hard slightly passed 5500rpm. My same exact engine combo without boost stops pulling around 4800rpm.

87z28fromhell

Won't see 1500rpm? WTF? cruising speed at 60mph. I am not looking for all out horsepower. I am building the most fuel efficient 350tpi e85 fueled engine I can. If it pulls to 5000rpm and runs 12's then that is all icing on the cake. What it will rev to and what I rev it to are two different things. And yes it is an auto. This engine however may not even go into a thirdgen so nothing is final on the tranny.
Nice car btw

xpndbl3

iTrader: (5)

during cruise you won't have any boost is what he's saying. with the converter unlocked it'll stall higher than that.

junkcltr

iTrader: (1)

If you put small T3s on it then it will spool at 1500 rpm under a load. It will not make 10 PSI, but it will spool. Crusing at 1500 RPM it will not spool. That is the great thing about turbos. There is no waste of HP. It will probably get you in the 12s too. Choose your turbos wisely.

87z28fromhell

I know this is apples and oranges.....but how is it that a diesel can build a sh*t load of boost at low rpms? There must be some similarities. I know some diesels run 25:1 crs but surely 10 psi at 1500rpm-2000 rpm must be possible.

xpndbl3

iTrader: (5)

diesel turbos are huge, their redline is typically 3500....so that's how the compressor maps are setup. Why do you want boost at such a low rpm? planning on drag racing while shifting that low? At part throttle you get no boost which is nice for fuel economy, unlike a roots blower that will always be robbing power to spin, the turbos are just along for the ride essentially at no boost.

junkcltr

iTrader: (1)

It is just like a gas setup. Put a small turbo on it to spool at low RPM. Look at the HP on a diesel. They are low HP. Look at the torque. It is high, low RPM with boost. Your gas engine would be the same. Most people install turbos for more HP at higher RPM. You don't seem to want that.

87z28fromhell

exactly what I want. All I need is compressor trims to achieve this.
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why would no boost at part throttle be better for fuel economy? I essentially want to make as much low end torque and hp for the very reason of fuel economy.

PETE

iTrader: (1)

What was trying to be conveyed to you was that a stock converter will flash above 1500 rpms, so basing the boost at 1500 rpms is illogical.

I had a Ball Bearing 61mm turbo and could only get 2-3 psi at that rpm. In order to get that psi you'll need to generate more exhaust energy to spool it up lower in the band. Easiest way to do that is to increase the rpms through a higher stall converter or use a 502 bigblock to spool a Te-44. Even the stocker i believe is around 1750 and could stall a little higher once loaded.

Take some advice and do not look at boost pressure. It doesn't exist! Calculate the cfm needed for your turbo to feed the cubic inches you have. Worry about bleeding the excess boost off with a gate later.

Unless you're gonna run a t-32 or a small mitsu turbo it'll prolly take a little more rpm to achieve the psi you want! You'd have to do some serious map searching though. Too small of a turbo would run out of steam before your powerband.

Fuel efficient and forced induction should not ever be put in the same sentence. Even when not under boost an FI engine will 9 times outta 10 get worse mileage. On turbo cars you have pumping losses on supercharged cars the crank turns the gears of the SC by a belt! There will be more losses than an NA car.

The BSFC is as follows .45 .55 .60 for n/a, SC and turbo engines. That's not a guestimate it's physics and cannot be worked around because you're using a different type of fuel.

What I'm trying to say is don't worry about a fuel or a psi. Think what you want the car to do then build for it.

They're are many guys that will tell you to do this or do that that have never had any experience riding in a FI car nevermiind trying to set one up. Use the mistakes of everyone here as a guideline.

Hell I've blown about 6 sets of headgaskets running boost! If you cannot learn something new everyday your life is a wasted one!

Also if you want examples or advice on a build, please give cubic inches, intake setup and heads. it'll help the guys trying to give you the right info on a turbo size.

HTH!

junkcltr

iTrader: (1)

In the end I think you will end up with a very small cam and a diesel torque converter in the engine to achieve that. With a small turbo and lots of off idle torque it is going to make the stock converter stall higher. That is why diesels have very low stall converters. You need a small cam to get the powerband as low as possible. Much like a diesel powerband. The small turbo will work with that setup. I don't see the engine revving past 4000 RPM. Probably around 300 HP peak with all kinds of low RPM torque. A single T3 sized turbo for a 3.0 liter engine would do it. Definately not a "normal" gas HP turbo setup, but heck it would be neat to drive. It will probably idle at 400 RPM with the small cam.

Oh yeah, it will not be fuel efficient. More torque means more fuel and turbo engines are usually around .55 to .60 BSFC (worse than N/A). That is why they turbo 4 cylinder engines. The are somewhat fuel effiecient and make some HP under boost.

xpndbl3

iTrader: (5)

I still don't get how the thread starter thinks that while cruising under part throttle he would get better fuel economy by having the engine create boost? More air means more fuel, a N/A motor would have better fuel economy for part throttle conditions than a turbo one.

87z28fromhell

pete.....The flashing and stall of said converter will not be an issue due to the lock up. I am searching for boost at such a low rpm for enough power to move a heavy truck or possibly thirdgen at around 70-75mph versus 2300 or more for the heavy truck. Lower RPMS in theory should yield more mpgs. The more power at lower rpms the faster the vehicle shoud move. Ever look at the epa mpg ratings on silverados? The v6 and the v8 are nearly identical on the highway. Sure gearing would involved but it also has to do with horsepower at a given rpm. Anyone have a theroy or sound proofs of a horsepower vs. rpm mpg function?

PETE

iTrader: (1)

Don't be offended how this comes out!

I think you need a little more knowledge concerning stall/ lockup/ flashing a converter, etc.

You will not be making any boost 0, while cruising at part throttle and the converter locked period!

Unless you run a switch or mod the chip you can't lock up the converter while under boost(W.O.T.).

The stall is how much the converter slips, flashing is when the converter when loaded goes beyong the rated stall.

Also what tranny are you gonna use? What converter? If you think you're gonna be locking a 12" converter under boost you'll have a non lock converter shortly thereafter. Ask me how I know?

I burnt a D5 converter(grand national converter) after a few passes locking it under boost.

If you are looking into gas mileage thats one thing, gas mileage under boost isn't gonna happen just due to the fact that the engine perameters are different.

When you are at part throttle you are using less fuel, when you enter power enrichment more fuel is added to compensate for the extra air.

You are better off setting the afr to around 15:1 while at part throttle and the converter locked concerning your mpg issues.

I hope this clears up some of the misconceptions......

LTR

87z28fromhell

No offense takin pete! I am however questioning your motives for posting such a response in terms of the functionality of a torque converter. I see no reason in my previous posts that would lead you to believe that I am ignorant as to how a torque converter works. The lock up of course will only engage when at part throttle and not under any heavy acceleration....I would have this setup regardless of boost or normal aspiration. Let me get this straight, are you suggesting that boost is not possible at low rpms? Interesting. As far as the lock up is concerned, let us say for the sake of argument that the tranny is now a manual with a heavy duty clutch. It would be nearly the same as the lock up at cruising speeds. No slippage would mean more of a load correct? It is to my understanding that turbos love a load? Could be wrong as it is just heresay. Any evidence in support of this would be greatly appreciated. I hope you are not offended Pete....well maybe not.

87z28fromhell

I love the idea of sequential turbos. I actually thought about it but wanted to keep it simple at first....one challenge at a time. I have talked with some engineers here at work about it. I work at navistar and produce the 6.4 powerstroke which has sequential turbos. Sure my setup would be exotic! Isn't that why most are here on tgo?

PETE

iTrader: (1)

Assuming a 2.73 gear u will turning 1700rpms. At that speed you simply wont be supplying the turbine with enough energy to spool it up. Even the smallest turbine prolly wont help much regardless of stick or auto. You may see some some boost in a manual if u powerbreak it while in gear rolling at 1000rpms, but not 15 lbs. Keep in mind u said cruising which means part throttle. turbos need heat n exhaust velocity to spin up.

PETE

iTrader: (1)

Ur looking for a diesel powerband, put one in it and u will accomplish ur goals but no e85. Maybe u could use biodiesel! also the reason diesels can spool at that rpm is the amount of exhaust energy each cylinder puts out. They are super rich which creates a lot of heat to spool it.
I say go 4 it and try to prove everyone that is telling you it wont work wrong!

87z28fromhell

honestly I wanted to improve the mpg of my 69 chevy 3/4 ton pick em up. I would love to put a cummins in there but that conversion is way too costly. So in all honesty diesel characteristics is what I am searching for. Sure I could build a high compression small cammed engine and get better mpgs but that is way too easy. So I will search for the right turbo to give me something at 1500-2000rpms. I am sure it will surge all the way through the hood when I get up there in rpms but hey it would be fun to watch. I am gonna call banks and turbonetics for some insight as I do not have the patience to figure out a turbo map. Also I read about the 1963 oldsmobile F85 Jetfire. Very cool! They had some big huevos to try that back then.

rob_m

Seems like you answered your own question! A turbo setup is a very expensive way to NOT get more MPG. The only way turbo's are economical is to use them to boost the torque of a much smaller engine. Your plan is seems completely contrary to your goals. A tiny turbine that boosts at really low RPM is EVEN MORE of an exhaust restriction, thus poorer MPG.......No offense intended.

shocker89bird

Good point Rob. Also how did the words E85 and better fuel economy end up in the same sentence? You usually need almost 40% more fuel over a gasoline engine so right there you are not getting better mpg's. If you are really looking for stump pulling torque you could build a 383 with the properly matched heads, intake and cam. Witha modified tpi setup you could make very good lowend torque. There is a link somewhere for a build up of 383 motors with various intakes on it somewhere and i recall aftermarket tpi intakes making 500 ft lbs at low rpms.

83 Crossfire TA

iTrader: (2)

Arg... another painful thread... I'm not even going to try to address all the problems here on all sides, and just skip to the heart of the matter- it's not possible.

Sure, you could size a turbo to spool at any rpm that you want, but the lower you go the lower the top end of it's power band will be.

Second, boost will not help MPG. Yea, there are some boosted combinations that get better MPG then equivalent NA, but they are typically smaller, much less powerful combinations without the boost and the boost is just there to get acceptable performance up top. If you were talking about sticking a 2L 4cylinider in an f-body and then use a turbo to make it drivable... then maybe.

Assuming that you ignore those issues and really build something that sees significant boost down low you'll find that drivability will suck. You'll be off and on the throttle constantly, as soon as you touch the throttle you'll build boost and the vehicle will start accelerating, then you'll let off to maintain speed and you'll loose boost and it will start decelerating. Not only will it hurt drivability but it will also kill MPG, constantly changing throttle position...

None of these are the real problem. The real problem is that boost is just increasing the ammount of air and fuel in the chamber and that increases cylinder pressure. Typically cylinder pressure is it's highest at the torque peak, and most combinations are detonation limited at that point. Significant boost at or below the torque peak will just be unusable. You'll need to absolutely kill the timing and will always be running on the ragged edge of blowing a head gasket or blowing up the engine. It will be impossible to keep it together.

Why can a diesel do it? Well, it works differently. It uses the cylinder pressure spike to ignite the mixture, there really isn't anything resembling detonation in one, and you just add more fuel when you want more torque. You can essentially add more fuel (chase it with air in the form of boost) till the parts just won't hold anymore, you'll never just break things with detonation because it's not there. Diesels also have a much lower power band, and the turbos are sized for it, they just don't need to move as much air because that 5.xL engine never sees more than 2500rpm or so AND you used to be able to just dump more fuel to spool the turbo (newer emission's regs prevent that now, black smoke is a no no now, so instead first all of them started getting smaller turbines and wastegates, now they're all going to variable turbines that can adjust to flow nothing down low and tons up top.

Drac0nic

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Drac0nic

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ZZ3Astro

/me sets an explosive charge in the bildge of this dredged up thread and sets it for thirty seconds!

BANDITSBC

GET OUT!!!! NOW!!!!

83 Crossfire TA

iTrader: (2)

woops... didn't notice, was searching for something and I guess I got one of the search results instead of a new thread...

sorry for reviving the stupid... I'd take it back if I could

Guest

Go find you an '82-up GM pickup with the 6.2 diesel. Those were EPA rated to do 31 MPG at 55 MPH. That's with a 700R-4, 3.42:1 and 29" tires. And most any local salvage yard will have these engines for a couple hundred dollars. The demand is low, the supply is high. Avoid the 6.5s, they crack. Then you can try to piece together your own version of the Gale Banks' Sidewinder turbo kit. Or use the turbo from a late 6.5.
You can't push the EGTs as high, but with marine injectors and a tweaked pump, you can get past the 200 HP limit of the stock stuff and the Banks kit. And unlike the heavier, longer Cummins, this thing bolts right in like a 454.
Plus unlike a Cummins, you don't have to do any mods to pull 4000 RPM. They'll go to 5000, but without boost they don't make any power past around 4250.
Diesels can benefit from boost at cruise because they can run lean. Like 50:1 A/F. Gasoline needs no less than about 17:1 without boost, and no less than about 12:1 with boost.

Street Lethal

iTrader: (16)

Oh my goodness, talk about an old thread....

Bingo, Pete!

Drac0nic

Out of all the threads to dredge up, this one? Seriously though the reason you run a turbo configuration is so that you stay out of boost when just in low RPM, and when you want power you hit the throttle and you get the go. For a set HP level this lets you run a smaller engine, milder cams etc. Rather than having a 5 or 6L engine to make 300hp you have a 3 or 4L engine instead. If you want MPG think smaller engine (perhaps one of the 5L or less "rejected" SB Chevies) and then put a decent sized turbo on it. Hell even a 4.3L V6 is a good choice if you can fab an intake as they were available roller and have 25% less displacement. Then again if you're that concerned about MPG the turbo setup, engine, fabbing etc. would buy a LOT of gasoline.