Hey guys, I'm hoping for info on twin charging an L67. As in keeping the super and adding a turbo. I searched and ended up finding a link to SPDDY's car, but that's about it. I want to keep the super functional. I'm not looking for people to tell me to ditch the super(right DH?) So please don't. Thanks for input.

http://www.ZZperformance.com has kits/info for this kind of setup.

Wowee! I tried google but it was all twin turbo and turbo with super removed. My search skills are sadly lacking... thanks! Any more info is great..like other fieros with the setup, etc. Or recommendations on what parts to buy rather than a kit...

I dont dislike twincharge... but if you are staying under 600whp.. its just not needed.

Anyway, there is no real tricks to anything, just set it up like normal, and setup a hobbs switch on the charge pipe that will open the bbv when the turbo is doing something.

You are going to need a underblower IC, as well as a turbo IC. You will soon find out that you are going to invest alot of time and effort into basically little to no gain, unless you are going for the fastest fiero.

[This message has been edited by darkhorizon (edited 04-22-2010).]

Well...if I wanted the most practical car I wouldn't have a fiero, aye? I'm not against 600whp... But that's probably excessive. I just want to keep the super. Can't hurt the low end. The plan is 3800sc/t with an F40. Most practical combo? Hell no...but it would be fun as hell to drive, and that's my whole point...

It would be harder to drive... not really much funner. The turbo brings power in easy, which the clutch and trans will agree with much much more so than a supercharged setup.

Again, not hating on it, just a word of warning here. It is not something that is hard to remove... it is just expensive with the extra intercooling required.

I'm coming from the sportbike world, where a typical stock "slow" bike will embarrass fierox or you or me. I want something that will be a bit brutal and unrefined. To each his own. Thanks for the input. I still want to twin charge, but I appreciate the difficulties being brought up...

There isnt a 600 in town that I am afraid of...

Going to run a stock cbr or zx 1000 in Justinbarts car here soon I think. 70+ and it is not that hard to put an edge on these things.

O..sorry. Hadn't heard you were down in the 10's yet... Well...a new liter bike will run low 10's high 9's from the factory...a zx14 or hyabusa should be in the 9's al day long.

quote Originally posted by TommyRocker: O..sorry. Hadn't heard you were down in the 10's yet... Well...a new liter bike will run low 10's high 9's from the factory...a zx14 or hyabusa should be in the 9's al day long.

Close to low 11s, bot no time slips yet (been to the track twice only got 1 run each time I went, but the track malfunctioned in a way that I didnt get it each time....) Justin is well, fast.

I was talking more about street racing type situations myself. A 9 second busa is not a common bike around here. The 1000s are going to be the faster bikes in town, as they are much lighter and most likely modded more. (take it to PM if you want to discuss lol)

I dont think FieroX would get embarassed by anything less then 8 second bikes(as if that would even be embarassing), whats should be embarassed is the liter bikes his car would run dead even with.

You're gonna need a big turbo unless you want gobs of axle breaking torque. With a good air-water intercooler and maybe alcohol injection you should be able to keepp temps down. Heat is going to be your biggest enemy. Its too bad those 3.8s have iron heads, they hold a lot of heat compared to aluminum. It should make for a fast car with a huge powerband.

I think you should go for it (provided you have the funds). 400whp should be easily attainable.

Good luck,
JoeCooley

I definitely don't have the funds to drop on a weekend lump sum build...but I should be able to pick up an engine, spare cradle, and over time start building it up. I'm recently divorced, so I have spare time and no one spending my spare change. This will NOT be a fast project... I actually was planning a completely different swap but that one was going to be limited to about 300 whp, and I decided I would rather have higher potential and not use it, rather than be maxed out from the start. O well, looks like there aren't any builds already, so I'll have to try piecing it together based on scraps... Time to re-read my turbo book...

I'm not fond of using a supercharger with a turbo due to intensely high heat that will be generated. An IC is a must with this type of setup. The fastest 3800 uses a twin turbo setup and with the incredible boost the engine is not steetable smooth. Sit down and ask yourself what you are trying to achieve and you should be able to do ust fine with one setup or the other.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote I'm not fond of using a supercharger with a turbo due to intensely high heat that will be generated.

Its not that bad... the supercharger is only adding frictional and mild compression heat when the turbo is doing its thing. The heat increase may even be offset fully by increased VE of the blower pushing air into the motor. So the actual physics behind twin charging leans a little bit on the more efficient (aka cooler boost) side of things.

For the engineer types out there... the motor will roughly be about 5.4L with a 3.8 pulley on the blower, about 5.7 with a 3.4 in terms of turbo calculations.

There are a few different alum heads availible for the 3800. ZZP made a custom run recently, and there are about 4-5 sets of GM prototype heads floating around somewhere.

How about having a centrifugal supercharger feeding into the Eaton? Eaton for the off-idle, and centrifugals are far more gentle than turbos. Your torque curve would look more like a torque ramp, but would be stronger at all rpm than just putting a centrifugal on an L36 version of the 3800-II.

quote Originally posted by Isolde: How about having a centrifugal supercharger feeding into the Eaton? Eaton for the off-idle, and centrifugals are far more gentle than turbos. Your torque curve would look more like a torque ramp, but would be stronger at all rpm than just putting a centrifugal on an L36 version of the 3800-II.

True, this is more commonly done than the turbo setup.

It is still far cheaper to do a turbo setup than a CSC though... much more power per dollar.

lighter sorry, it was bugging me.

I would only go for a twincharged setup with intercooling after each compression stage.

Yeah, just a turbo is sufficient for xxx hp - but there's going to be lag.

The twincharged setup is going to be less laggy, more like a larger engine with a more mild turbo boost. This will give you more of the intanglible "fun factor" when you step on it and get instant power.

Here we go with Lag again...

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Turbo 3800 E85 5spd spec3
11.74@123

Sort of but not really.

You are not compound boosting here, you are just either or boosting... The blower is in all reality turned off less than a second from when you go >30% throttle.

quote Originally posted by Justinbart: Here we go with Lag again...

I wonder when people will realize there is a difference between lag and spool time...

The "lag" on any T4 turbo / 3800 combination is going to be nearly indistinguishable between that of a M90.... Spool time depends on turbo size, and I can tell you from a very very broad experience of many turbo 3800 setups that have came through my garage.. it is not a hard thing to deal with.

The common definition of lag is the time it takes to go from vacuum, to full boost.
This could even be done at a constant RPM.

Bottom end power has nothing to do with lag.

Check out Bob C on Club GP. He seems quite happy with his twin charged setup.
I haven't done it but it seems quite simple. 2 IC's, larger turbo than you would normally get, an actuator to open the boost bypass valve already on the SC when there is boost in the throttle body.

Here is one of several links on Club GP about twin charging:
http://www.clubgp.com/newforum/tm.asp?m=5241803

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'84 3800SC, XP cam, 3.2 pully, HPTuners, N* TB, 4sp, SPEC 3+ clutch, Aluminium flywheel, pacesetter headers, F355 body kit, weight reduction

quote Originally posted by pmbrunelle: The common definition of lag is the time it takes to go from vacuum, to full boost. This could even be done at a constant RPM. Bottom end power has nothing to do with lag.

Technically speaking, spool is the time it takes to go from vac to the first sign of positive pressure, then lag is the progression from positive pressure to the wastegate opening. And that being said, it is not that far off of a M90.

quote Originally posted by Dracor: Check out Bob C on Club GP. He seems quite happy with his twin charged setup. I haven't done it but it seems quite simple. 2 IC's, larger turbo than you would normally get, an actuator to open the boost bypass valve already on the SC when there is boost in the throttle body. Here is one of several links on Club GP about twin charging: http://www.clubgp.com/newforum/tm.asp?m=5241803

Why hook up a boost bypass? Isn't the point of a twincharged setup to compound the boost?

you want the super to give you instantaneous boost, then feed until the turbo is making max boost, then the turbo takes over and ideally the super freewheels...this is a street car, so I'm not going for 50 psi and 1200 hp....

quote Originally posted by 87_special: Why hook up a boost bypass? Isn't the point of a twincharged setup to compound the boost?

x2

I think the idea of having a bypass is to avoid the parasitic drag of the supercharger at full power.

Personally, I would prefer a slightly smaller turbo operating at a lower pressure ratio for less lag, with 2 stages of compression and intercooling.

I also don't see the point in having an intercooler sandwiched under the supercharger if you're just going to bypass the supercharger...

quote Originally posted by pmbrunelle: x2 I think the idea of having a bypass is to avoid the parasitic drag of the supercharger at full power. Personally, I would prefer a slightly smaller turbo operating at a lower pressure ratio for less lag, with 2 stages of compression and intercooling. I also don't see the point in having an intercooler sandwiched under the supercharger if you're just going to bypass the supercharger...

Even when the bbv is opened, the blower is still making some pressure ratio difference. ZZP swears by it, I also cant seem to explain why they think you need it.

The open BBV is there to free up horsepower, that is correct. Those stupid 44psi numbers in that mustang deal is just dumb... my buddies are making that on cheaper gas, and 22-25psi of boost. Hell the 2JZ I tune does a bit over 1000whp with a 3.0L and 33psi.... Nearly half the mustang motor.

quote Originally posted by darkhorizon: Technically speaking, spool is the time it takes to go from vac to the first sign of positive pressure, then lag is the progression from positive pressure to the wastegate opening. And that being said, it is not that far off of a M90.

I'm experiencing this on my turbo 3.4L as well. If a turbo is perfectly sized and matched, the spool up time is minimal. If you have an auto you can actually do a power brake hole shot with boost already in place. Over 9 -10 psi of boost is where an IC becomes a necessity.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Check with Jeff at Engineered Performance. He added a turbo to his SC Pontiac (Along with his limited slip differential.)

www.engineered.net