3.4 twin charged

Hello all I’m looking to add a turbo to my supercharged 3.4 as far as fuel mods and tuning what should I do. Was gonna order the 7th injector kit from urd for a piggy back ecu but don’t know if I’m just better off going a different way if I plan to add a turbo. Any insight on this would be sick. Thanks guys !

 

Two options for ecu of sorts, 7th and FIC 6, 7th is very much a bandaid, stuffing so much fuel that it can’t trim it out anymore. Fic6 is a ton more finicky and hard to wire but once working, is better than the 7th. It will work and will allow for being turbo and tuning closed and open loop as well as timing and not throwing codes. Fic can work bigger injectors with scaling to add the extra fuel.

I don’t believe pro charge is what you mean. Twin charging is the term for turbo -> sc and is very hard to do right. Sizing the turbo will be hard as well.

 

Thanks for the reply man, so instead I would be running a fic 6 bigger injectors and fuel pump ? I saw this guys video on YouTube but he doesn’t go into any detail about how he did everything

 

The problem with twin charging is the air has to bypass the supercharger when the turbo is in boost. Typically twin charging is reserved for low displacement japanese cars with 600cc engines.

There's numerous other issues, but you'd be far better off selling the supercharger and installing a turbo on its own.

 

You don’t have to bypass the supercharger at high rpm. The supercharger is a fixed displacement, therefore if you increase the pressure in, the supercharger can’t become a restriction. The reason you may want to bypass it is because you don’t want as high of boost as it will make and you want to get ~20 hp back from spinning it.

I hate seeing all the “just go turbo” comments on these. Sure you can get a proper sized turbo and make power fast, but twincharging that turbo can net you earlier boost by sometimes 1500-1000 rpm and may lose 30 hp at the same boost but the power under the curve is (typically) more. Not great for drag strips but in corners and driving on real roads it can be better.

@Jbogstaco yes fic6 fuel pump injectors, probably methanol too if you did twincharge to keep temps down and increase octane. At that point porting of the supercharger can increase efficiency and create less heat but it’s all what you are after, we don’t know what you are looking for

 

I had a supercharged corolla and it was popular to twin charge it in the early 90s, it had a clutch on the supercharger. There is nothing efficient or beneficial to twin charging anything. It's a pipe dream. Upgrade the supercharger or replace it with a turbo.

 

Tell that to the Lancia Delta S4 or the twincharged vw motor more recently. Twincharging reduces turbo lag. That is beneficial to performance. It also allows for a larger turbo to be put on the same engine and less stress on the turbo as it will not have to make as much boost, only 2/3 of full manifold boost if sc is running ~7 psi of boost. Therefore no turbo lag or the same lag with a better flowing (larger) turbo. VW used twincharging, sc into tc to get better lag times and increase low torque, then bypassed the supercharger in higher rpm when it would restrict the turbo. They had a clutch on the sc as well and did all of that for Better mpg.

 

Thanks for all the reply’s guys so my plan was to get the Cx racing kit as a base and just go for a different brand turbo . As far as running the turbo into the supercharger is the blow off valve on the charger just gonna dump the boost the turbo makes ? This is the video I saw that made me wanna do this c

 

I’ve seen that video before. I’ve got lots of respect for folks that modify vehicles to that degree. Especially if the mods don’t accelerate (pardon the pun) wear on the vehicle in any major way. One other thing to possibly consider is how much less room you’ll have under the hood to carry out routine maintenance without a bunch of disassembly of the added goodies required.

But sweet bastard, that must be fun when it’s time for a full send of the skinny pedal

 

No, the bypass for the supercharger loops the inlet and outlet of the supercharger together, so it would still make the turbo’s boost but it would stop compounding the boost. There are 2 ways to set it up on our trucks:

1. turbo always compounds into supercharger, turbo makes about 8 psi and compounded into 19.5 psi of boost if sc is running 7 psi. Lag will be super short and it will lose a bit of hp on the top end. But it does not have to be very complicated with no programming needed.

2. turbo compounded by supercharger and into high rpm the bypass opens. There will be a bit (more?) or the same lag dependent on turbo, the turbo will need to be able to run the high boost you want to run without compounding. When around ~3500 the bypass will open and the sc will be less of a load on the truck and the turbo will make 100% of the boost. The bypass will have to be actuated by something you design and code. It will have a bit more hp on the top end but it is very complicated. Additionally if you were able to put a clutch on the pulley you could get about 30 hp on the top end and run a VERY small pulley, heat would be very large with it but you could probably get 15 psi from the sc up until the 3500 rpm.

Essentially what you will have is a turbo 5L because the supercharger increases the displacement (in the turbo’s POV). You will need a very large wastegate and bob as well. @BlackSportD anything to say? I know you looked at this a long time ago but not sure if I missed anything.

 

I can appreciate the engineering challenge, but at what point does it just make more sense to do a motor swap?

 

Dunno, If you already have the supercharger and aem for normal, it would probably cost 1600 + turbo and it would be one of a kind, it all depends, also management for an engine swap can be kinda hard, right? $1000 for manifold $400 for fuel pump and good injectors $200 for intercooler and piping, and for that price you can get a stock motor swapped in? (my numbers there re probably all over the place) it all depends, I think I read you can get 18 psi before the motor pops 100% over on customtacos. Thats something like 400-450 crank or 370 wheel but those engines were almost brand new back then and your tune would have to be perfect. or that turbo only has to spool 7 psi for full boost, probably 2000-2500 rpm full boost.

In that video the turbo was spooling REALLY fast and soulded great, but idk what it should sound like.

 

I'm not even sure you can do a TRD supercharger for $1600. And that's a nothing-special factory equipped SC. And now we're talking about nearly doubling the HP (or more than doubling a stock n/a motor)? Upgraded internals to handle all that power aren't cheap either. Or are we just throwing more air/fuel at it until it pops?

I guess it also depends on what you're going to use it for. I mean, are we talking about street racing, towing, or just being able to do burnouts with that glorious forced induction whine?

For me, I'd much rather spend the time an money swapping an R2.8. IMO, 4x4 pickup trucks need low end torque more than they need high end power, and we could certainly use better MPGs, lol... Seems like a better fit for the overall package of a compact/midsize pickup truck.

And yes, I do realize I'm being a boring, practically-minded, stick in the mud, lol.

 

My question is the same as jbrandts.... whats the use of the truck gunna be? that video is bad ass for sure but whats the practical part for ya? not knock just wondering!

 

Hey guys thanks for all the responses . I don’t want any crazy boost setup at all. Just the benefits of the turbo and supercharger . That guy in the video had been running 20 psi for 60k on stock internals . Don’t wanna do anything near that because I want to keep my truck somewhat reliable . It’s my daily driver till it’s warm enough to be on my motorcycle . My goal was to be at around 14 pounds of boost between the 2 . I don’t have any kind of computer yet . Just running the sc setup on a stock ecu

 

Was thinking if you already had the supercharger and fic, probably burnouts with a whistling whine and making 18psi and see when she pops. Maybe keep a conservative 16 and build a motor for 25+ psi on the side, then push it till it pops. Would be really fun to see where the stock motor gives while it’s just being cool at the same time. Turbo and the sc at the same time is just awesome in my mind, hopefully some day I can have a built motor for a huge turbo, sc etc For huge power in a stocking looking truck.

power to weight at 18 psi would be crazy

 

That’s the goal man . I just wanna be keeping up with bigger and newer trucks . I’m on a 3 inch level with 33s so just the supercharger is not cutting it anymore

 

If that’s all you are looking for, 2” pulley and methanol with an aem May be all you are looking for, ~270 whp. You can make around 300 max on the sc with all the mods possible

Twincharged will be a lot faster than the newer trucks. Something around an m4? equivalent in power weight.

 

I hear a bunch about belt slip with the smaller pulleys . I’d rather just put out the extra couple grand to have a truck that’s way cooler and a lot more efficient you know . Plan on having this thing till the frames gone

 

Definitely way cooler, not 100% sure it would be more efficient than a single turbo, boost ratios multiply and I think efficiencies do too. Though against belt slip it might be? Not sure.

Fic6 can be hard to source, EPA made it become discontinued so no more new ones. I was able to get mine here on the bst threads though so you never know. With the scaling, you should be able to have a perfectly good idle even with big injectors. Though I don’t know what would be a good size for the in between and final.

definitely not a bolt on mod but if any car would be close, it would be us