Engine/Transmission (1994 - 1998) Twin turbo set-up?

[Bad340fish]

My Understanding(which can be quite backwards lol) is that a Bypass goes on the Cold side of the turbo and keeps the air from kicking back on the turbo when the throttle is shut. It could not be used as a wastegate since it would not controll turbo speed. Went to a mustang Grand National Shootout this weekend. A kid had a fairmont that had 2 TurboCoupe Turbos on it mounted on upside down Mac headers running to a holley carb. Ole Sleeper went a very quite 9. 94 with a bench seat and all!!! Very Cool

Clark

 

[HoleshotHolset]

What you're thinking of is a 'blowoff' valve..... HKS makes a really nice one for big $$ called the 'Super-Sequential'... . they sound soooooh cool though.



Blowoff valves send the surge air that results from going from boost to vacuum in a gasser to atmosphere... or in some cases back into the inlet of the compressor of the turbo. They help extend the life of the turbo by getting rid of that surge that likes to induce thrust movement, which is a bad thing.



For turbo/supercharged gasser cars/trucks with manual trannies... . they also help to keep the turbo somewhat spooled in-between shifts, by not allowing the surge air that resulted from the throttle plates slamming shut to go back through the compressor section.



'Pop-off' valves do a similar thing, but they are pre-set to go off at a certain pressure, instead of going off when a vacuum signal is present. Think of the pop-off valve as a high-pressure relief valve on your air compressor or boiler.



Matt

 

[HVAC]

Double Turbos

DBR,



QUOTE:

"Havac:

Thank you for the tips, I appreciate it! I have to comment on how clean your set-up is, Nice Job!

Does it ever rain in California? Your engine compartment is to clean. "



Geez, that's cool if I helped you any.



Thanks for the compliment on my latest system. Being an HVAC contractor my job is to build air systems that control the atmosphere within your home or commercial building. The fun part is to do it with a measure of style



Actually, we get a LOT of rain here in CA! It starts about January 30th and ends February 2nd or so. Absolutely brutal Seriously, I keep after the engine compartment pretty aggresively. I go to a lot of shows and the products I sell are targeted for the engine.



Earlier on this topic I referred to a drag race event. Well I was there this weekend and I have an excerpt from a email I sent recapping the weekend. It pertains to the twin turbo topic BTW.

-------------------------------------------------

Just the day prior to the race I was busy reconfiguring one of the cold air pipes and trying to fix my clamps and hoses to keep them from

spitting off when I hammer the throttle. Well I'm happy to report that when I left the welding shop headed for Palmdale I stabbed the

throttle and saw 53 psi! No blown hoses either!!! At the track Saturday I was further pleased with the turbo performance. I hit 60 psi

on the last run! That was the only good run I had btw. I expect I'll be at 65 psi with the propane operable and that covers my best

scenario goal as far as peak boost goes. There isn't a (single) turbo out there that can run those numbers and last. With these twins I

am getting cooler air while only driving the turbos at a moderate pace and maintaining wonderful drivability to boot.

-------------------------------------------------- FWIW



#ad


The top pipe is new as of Friday to give me a better entry to the upper turbo.

 

[HVAC]

Another View

These picks are courtesy of Mr. Gary Cleverly who took them at Palmdale on Saturday.

#ad


Look just behind the oil filter and you can see the tiny K&N filter I'm running. Actually you can see the chrome top plate. If I were to do this again I'd provide for more clearance from the front of the lower turbo to the oil filter. I will be working on another intake system for the lower turbo to help supply it with cooler air through a larger filter.

 

[BigYellowIron]

How come no one Has split a manifold and run two smaller turbos, like one for 1-2-3 and another for 4-5-6. Just a curiosity question. Your biger Cats run a turbo per bank on the v blocks.

Would this do the same thing as piggy backing a bigger turbo with a smallar one. Maby room is the reason? Enlighten me please, that has always been a thought of mine on twins.



Adam

 

[MY6EATSV8'S]

the basic reason for doing this is because of space available I believe.

the reason for not doing it on our motors is because it would not be any better than one turbo. The reason we go to two is to compound boost. Basically a turbo will only put out a maximum amount of boost under 400degrees outlet temp, when you get above this its called going off the map because the hotter air does not carry as much oxygen but will make more volume(ie boost) so in essance because to do two in parrallel you could not increase boost and take advantage of more air. Basically 35psi of two turbos would still equal 35psi of one turbo with twice the headache to make them work.

You can benifiet from staging turbos because basically you can make one turbo feeding 25psi to the next turbo, witch doesnt know//care that their is 25psi in front of it, so it in turn makes 25 more. If done properly this could equal 90+psi boost. So 25+25 does not equal 50, more like 90.

 

[HoleshotHolset]

FWIW,

Two turbos working 1/2 as hard as one (when compounding) is a good thing... .

Going off the map is a very bad thing.



Matt

 

[400Magnum]

Still trying to understand...

Okay, I understand what you just explained about one turbo feeding the next, they don't have to work as hard, so the air stays cooler, and you get exponential boosting.



My questions are:

1. Do you get additional boost all the time? That is, when you're just driving easy around town or whatever, do you see more boost with twins than you did with just one turbo?



2. What do you do to take advantage of the extra boost? That is, are you increasing the fuel delivery as well? If you are, is the fuel increase at all rpm's or just when you stab at the throttle and you get the big boost numbers? Are you doing this just by moving the fuel plate forward to increase fuel?



3. I asked this a while ago on another site, but I'll ask again here. Is there any reason why a person couldn't do the same thing by using a belt driven supercharger? I was thinking that a person could use a small belt driven roots-style blower to feed air into the turbo, so that there would be virtually no turbo lag. Plus, wouldn't you also get the same exponential boost effects? This supercharger makes about 7 psi boost from idle all the way up to 20,000 rpm. Maybe it won't make boost to the degree that you're getting with twin turbos, but there'd still be something, wouldn't there?



If I'm way out in left field, feel free to let me know. The reason I ask about the belt driven supercharger is because I was able to get my hands on one a while ago for another project that will never happen now, but I still have the supercharger. It's off of a ('scuse me) Ford Lightning truck, and it looks like it should fit down in the area where the A/C compressor would normally go, but since my truck doesn't have air, I think I have room for it. I could route the incoming air to the supercharger, which gets dumped into the turbo, and then goes to the intercooler. But, before I dig in and start ripping things apart and rigging things together, if you all don't think this is a good idea, then I won't bother with it.



Any advice and/or insight would be greatly appreciated.

 

[DBR]

400Magnum



I believe HVAC would be the one to answer some of your question.



I finally have the twins installed and ready to go with just one issue left to resolve, the air filter. I was hoping to use the factory air box, but no luck, hits the cold side piping. I will use the BHAF until I can come up with a better solution. The next bit of work to do is install the replacement clutch from South Bend and bolt up the transmission and related components. I hope to have the truck on the road by this weekend as I'll be out of town on business the following week. Hope all this work will be worth it. DBR

 

[Strick-9]

400,



I think you should try mounting the supercharger on your truck. No, I don't think it would be a waste.



If indeed the charger creates 7 psi at idle and maintains this throughout the rpm range, you would lose a little power in the lower rpm range because the parasitic drag of the charger on the crankshaft and the fact that you can't make more power idleing with 7 psi of boost than without it. It would create instant throttle response though!



I would love to hear about it.



-Chris

 

[Bad340fish]

RPM

Your going to need to find what the most efficient RPM range is for that blower. Then your going to have to overdrive it most likely. The low RPMs of the cummins is probably not the best thing to try and use a gasser blower on. If you could get the speeds up it just might work

Clark

 

[HoleshotHolset]

I'd like to see that supercharger make 7psi at idle..... the F*rd Lightning Bugs only have about that much boost at WOT (stock)... even if it's 14psi at WOT, that's still not too much.

Not to mention that blower is a Root's style... not very efficient.



We would be better off using a centrifugal supercharger like a ProCharger P-600B or lager. They're designed for more efficiency and can make upwards of 25psi with the right pulley. So if we had a turbo feeding the supercharger and compounded the boost, we might be gaining something.



Parasitic loss is too great to even consider a supercharger. A supercharger can eat up to 35% of the power output of the engine to produce more power. Turbos do not eat even a fraction of that amount. Take advantage of all that exhaust coming out of our engines..... hook up two turbos...compound them... . and hold on tight.



Blowers on diesels is for two-stroke Detroit-Diesels.

This is HOLSET COUNTRY!!



Matt - my $. 02 worth.

 

[400Magnum]

Oops

Okay, I made a slight error, the supercharger is only designed to spin up to 12,000 rpm. I was thinking of one of the smaller model superchargers when I previously said it'd go to 20,000 rpm. It appears from the charts for the supercharger that it'll make boost from 4000 rpm (on the supercharger) to 12,000. I don't have access to the actual performance maps, but according to the Eaton Supercharger website, it heats the air up the least amount between 4000 and 8000 rpm. Power consumption is almost linear across that range, starting at 10 hp at 4000 rpm, and about 24 hp at 8000 rpm, and a whopping 47 at 12,000 rpm. Seems like it'd be a lot of drag on the engine, maybe this isn't such a great idea after all. But, this supercharger sure does seem to wake up the Furd gasser, so it must be doing something good. One reason the Lightning doesn't make a lot of boost is that they are still having to meet emissions. More boost means more fuel which means more pollutants. They had to strike a fine line between performance, economy, noise, and emissions. The blower will make a lot more boost, it just makes more noise doing it, and that's a big no-no in the eyes (and ears) of the noise pollution nazis these days.



I'll have to measure and compare the size of the crank pulley on the truck and compare it to the one currently on the supercharger. I have a few options as far as getting different pulley sizes, so I'm pretty sure I can get the blower adjusted to whatever rpm I need it to run at. The pullies that I had for the other project were ratioed to give me 7 psi, so depending on the truck's crank pulley, I may be higher or lower.



The next question is this. Not wanting to sound stupid, but what will this extra boost do for me? I mean, just having extra boost alone won't do anything for me, right? Won't I need to move the fuel plate to get more fuel in there with the extra air?



The reason I was thinking about this in the first place was because I already have the supercharger. Basically, I'm trying to get by with spending as few $$ as possible, yet get a noticeable boost (no pun intended) in performance. So, getting a belt driven centrifugal is out of the question.

 

[HoleshotHolset]

To take advantage of any added boost, you will have to add more fuel... . that's all there is to it. On a gasser, if you add boost and don't add fuel... you run it lean and blow it up... or detonate from going beyond the efficiency map and blow it up.

On a diesel if you crank up the boost and not add any fuel, you just run lean... . and not make much more power... you won't be hurting anything but the boost creating device, be it a supercharger or a turbo.

Good luck with the belt-routing..... you gotta get that thing just right otherwise it will spit belts and you will be hating life.

Been there, done that... . got the T-shirt.



You will find that the stock turbo (HX-35) with a good turbine housing will make upwards of 400hp with proper fueling... . granted at these high boost levels... it's life is limited, but if you only visit Highboostville on occasion, it'll live.

Sell the Roots blower to a gasser..... and spend the money on upgrading what you already have working well for you.



Matt - $. 02 more... .

 

[Don M]

Turbocharging is the only way to go on a Cummins.

Why pay the heavy price of parasitic load from a blower?

The exhaust stream turns the turbine wheel for free.



How ya gonna cool the air charge from a roots blower?



Don~

 

[HVAC]

Supercharger?

While I have only scanned the new posts, you guys seem to be all over this. You need more rpms to make a supercharger work well. At the drags I shift at 3000. I spoke to several centrifigal blower manufacturers and we were talking about 40,000 rpm on the charger to make it work right. And then it wasn't going to generate the kinda boost I'm lookin' for. Ten psi doesn't float my boat!!! Anybody here wanna do the math to achieve 40,000 rpm with my engine doing 2000? Twenty to one eh? Now figure the pulley diameter!



Origionally my interest was to decrease egt. I theorized that if the turbo is the greatest offender where egt is concerned then let's eliminate it! Notsofast Sherlock!!!

 

[HVAC]

Blowers vs Turbos/ Another Campfire Story

Local dude has a blown alcohol big block in his puller tractor. Puts brain into gear and next thing you know he has four large turbos and no blower!!!



Well, the left bank front two cylinders feed one turbo, the back two feed another. The front two cylinders on the right bank feed a third turbo and the right bank rear two cylinders feed the fourth turbo. Talkin' lotsa plumbin' here friends



Well, they calculate they are saving 500 horsepower since they don't have to drive the blower anymore!!! The turbos are in parrallel and run around thirty pounds. This is fine for a gasser motor. They are very happy with the results indeed. Sometime I will explain how the alcohol fuel injection works in conjunction with the boost pressure. They have a fair amount of electronics onboard. Very cool.

 

[400Magnum]

A little more of my goal

Okay, I guess I need to say that I'm not trying to turn my truck into a drag racer or a pulling truck. I use my truck as an everyday driver, unloaded, no towing. I hardly ever get it above 2000 rpm, I typically cruise at 1500-1700 rpm. I drive it fairly conservatively because I need to get as much fuel mileage as possible. My original thoughts for the supercharger, after reading the start of this thread on the twin turbos, was that I might be able to use the supercharger better for my type of driving to overcome the little nuisances that the basic diesel has, like being a little slow taking off in everyday driving in town, or just getting up the initial burst of speed to pass someone on a two-lane back road somewhere. Since I occasionally see smoke and the fact that the inside of my exhaust is black, I thought I may even gain a little fuel efficiency by adding some more oxygen to the mix and burn up the rest of the fuel that's going out the pipe. Since I don't run the engine that hard, I wouldn't need to turn the supercharger too fast in order to supply enough air to help things out, so I really won't be losing a lot of power to turn the supercharger.



Not that I wouldn't love to do what some of you guys are doing, but it's just not very practical for me right now. I just thought that if I could introduce a little more boost into the system with something that I already had laying around so that it wouldn't cost me a bundle, and I wouldn't have to worry about frying something like a person might with a gasser by getting too lean, then I might go for it.



I was just looking for advice/information/opinions on whether it was workable or not. I'm not looking to get a huge change in performance like you'd get by installing a TST plate or better injectors, and I can't afford to go buy other parts, I'm just trying to get ideas for stuff that I've already got. I just wanted to make it clear what my goals are/were.



Thanks for the input, I do appreaciate it.

 

[MY6EATSV8'S]

ok here is a revelation, take advantage of the easiest 60hp and 1. 5to3 mpg gain you can, slide you stock plate forward, then move the afc forward a smidge. If you have egr deleate it with a 94/95 intake manifold. Done. Cost=00000. 000 unless you have to buy a 93dallor manifold.

 

[Brandon]

not to change subject just read yours 6' well i had a dairy man make an air horn in front of me in an hour outta scrap... ... ... ..... all i could do was laugh but... ... ..... it worked cost... ... ..... scrap pipe and about 4 welding rods... ... ...



i couldnt stop laughing,