paulmoore

Just like the title says...I know just enough about turbos to be dangerous lol! Anyways, engine is a 383 stroker, fully forged rotating assembly, 9.5:1 CR with older AFR 195 street heads (1205 port). Naturally aspirated it puts 510FWHP(420 to the wheels) but I am looking to up that to 800 FWHP. I tossed the twin turbo idea around but I think I will end up going single to keep cost and complexity down. On top of that, I am going from carb to efi. Here is what I would like to use so far...and sorry for the long post!

1. FAST XFI 2.0 to handle the fuel injection, not sure which harness to use...maybe the TPI harness? FAST XFI 2.0 will work with my MSD distributor/6AL/Blaster Pro HVC coil with an adapter. I will need to implement a boost retard to dial back the timing.

2.Accel DFI Single Plane EFI intake with fuel rails OR the Edelbrock Pro-Flo XT Intake Manifold (however, i read that it is only a 1204 intake port???). I am leaning towards the Accel because the air inlet is 'centrally located' ie. it seems like it would allow for more equal airflow distribution amongst the intake runners. Unless there is a better single plane EFI intake out there...then please let me know!

3. Fuel pumps...here we go. I researched the twin 255lph walbros and like the idea, but do I really need to run a hobbs switch? It is my opinion that a fuel pump would not like to be on when boost hits...then off...then on. I could only imagine that a constant on/off/on/off cycle would wreak havoc on a pump. Personally, I don't see a problem running both pumps at the same time as long as a return style regulator is implemented so any unused fuel gets sent straight back to the tank. This avoids fuel being overheated.

On a side note, I would rather use the largest, in tank pump that will fit with the factory sending unit. I read somewhere that dual 255's are good for about 1200HP-1300HP. Doing the math, each pump supports roughly 600HP, which is 2.35hp per liter. To reach my goal of 800HP, I would need 340lph. I read about the walbro 340lph as well as the 400lph designed for E85. Would either of those work? Would the E85 pump be compatible with gasoline and if so, would it change the lph measurements?

4. Fuel injector size. I saw the sticky on the forums about size and the formula was (Max HPx.65 for turbo then divided by 8) My equation ended up as 800HPx.65= 520/8=65, meaning I should run 65# injectors. After reading some posts about other people's cars it seems like 65# is too low. There are some using upwards of 80# injectors. Am I missing something?

5. Camshaft. Currently I have the 12-433-8 grind COMP Cams Hydraulic roller retrofit cam/lifters. Specs are .520/.540 lift 236/242 duration 110 LSA 106 IC
Needless to say I understand that the LSA in too narrow for turbo, so I was thinking about using the Nitrous XP line seeing as how they are also a retrofit roller and I can keep my lifters. Either the NX288HR or NX276HR. The 288 is the same lift as my current cam, .520/.540 but with 236/248 duration, 113 LSA and 108 IC. The 276 is smaller .502/.520 lift 224/236 duration 113 LSA and 108 IC, and may end up being better as far as idle, engine vacuum, part throttle, etc.

I am not sure what fuel pressure regulator to run. Any suggestions? I want something that is a return style that rises at a rate of 1:1. I would figure that the regulator comes after the fuel rails like most efi cars, correct? Or is it before like how the carb setups run? Most regulators I see for EFI have -6an outlets and return which seems too small to me.

Some other odd questions...do I use EGR? It seems pointless but hey, I am new to this.

Widebands. I want to use some sort of AFR monitoring, but does it go in the turbo manifold or after the turbo? I would imagine that it shouldn't matter because the exhaust gas properties don't necessarily change by going through the turbo, albeit a change in temperature. I read a post about putting it 3 feet after the turbo? Can someone clarify?

Last but not least...what turbo should I run? I called a couple of places and it seems like they want to sell me the biggest, baddest stuff that they have. For example, I called a company called Precision Turbo and Engine, and they suggested a PT7675 CEA turbo. Here are the specs...

HP Rating: 1,200
We know you want to be the best both on the track and off. Whether you're a diehard racer or just looking to boost your daily driver's performance, Precision Turbo and Engine has what you need. For exceptional power and unbeatable technology at an affordable price, PTE can help you find the perfect turbocharger for your unique setup.

Ball Bearing Option Available
(add $911.00 to MSRP)

PTE's PT7675 Turbocharger features the following:
• Exclusive CEAŽ (Competition Engineered Aerodynamics) compressor wheel machined from a 2618-aluminum forging
• Higher efficiency and faster transient response for maximum power and performance
• 76mm inducer compressor wheel
• Compressor cover options:
- "H" compressor cover 4.0" inlet/3.00" outlet
- "Ported H" compressor cover 4.0" inlet/3.00" outlet
• 75mm, 84 trim turbine wheel
• Turbine housing options:
- T4 Tangential .81, or .96 A/R with 3 5/8" V-Band discharge
• Available with either a Hydrodynamic 360° thrust bearing system, or an Air-cooled, dual ceramic ball-bearing center housing rotating assembly (CHRA)

Salesperson explained that I will have room to 'grow' into this compressor. It should make my target of 800 FWHP on "Low boost" which he said was 8-10 PSI. Boost comes in at 3000 RPM, with full boost between 3800-4000 RPM. I asked him about the ball bearing center section as it should allow for faster spool up, and in his estimation boost would come in 300 RPM sooner.

If I missed anything please let me know. Sorry for the long post but I want to make sure that I get this stuff right. So let me hear your thoughts and suggestions, and above all else, thanks!

Jay_rich

iTrader: (4)

To give ya an Idea my first build was a 383LT1 with a single T6 flanged Garrett semi truck turbo. it was only around a 73-74mm. I was making 581whp on 7-8psi.

Now for fueling I dont find the hobb switch necessary. I originally had one wired and then one of my pumps wasnt putting enough pressure (likley a split hose in tank) So I just wired them both ON. A couple of my buddies also run them both ON all the time.

I also ran an aeromotive 1:1 rising boost regulator. So when you go into boost it rises the fuel pressure according. -6an will feed 800hp. But I would suggest doing a -8an Feed with a -6an return. Your call on pumps. I would look into either twin 320 stealth pumps or even twin walbro 400's. Both will give you more than enough fueling.

Injector size at that power level i would be running at least 80# injectors if not maybe 96's. Im assuming the FAST will do low impedence? if so maybe even go up to a 120# low impedance in case you decide on E85 since you need a lot more injector for it.

Camshaft you are best getting a custom grind to match the combo. I would guess it would be in the 23x/23x range. my 383 was speced with a 230/236 114lsa I think. That was calling comp directly. I would suggest getting a hold of someone who know's their ****. Off the top of my hear guys like Martin at Tick performance (he is on ls1tech a lot) or Lil John on Yellowbullet. He can spec you everything from turbo etc.

Ditch the EGR

Wideband Will be put in after the turbo. These kinda sensors do not like pressure. So anywhere after the turbo will be good. I assume you wont run narrowbands? There is a debate on pre or post turbo. I ran mine pre turbo since it was a single.



That 7575 will end up killing a 383 up top...I would recommend a Borg Warner S480 1.32a/r for a 383 single. Which Lil john would probably also recommend since he works with Jose' at Forced inductions. The nice thing about the S480 over the S475 is it doesnt create as much heat from what I have read. Also like Lil John will tell ya the Borg's will like a bit of overlap around 0-4 degree's to get the turbo moving. So if you like that bit of Chop at idle you will get it. Only my 370LS setup I ran the Speedinc TU2 236/236 112.5lsa. it had that nice N/A chop idle


It all depends on how much of a street car you want. a T6 flanged turbo will fit in the battery area and keep you from doing a lot of cutting. I ran mine that way then on my 370LS build I decided to cut the rad support out, move it WAY forward and do a center mount on the turbo. This time around Im gonna try to stay away from doing that.

Hope I answered most of your questions!

Jay

Badass355ciz28

iTrader: (17)

paulmoore

Jay_Rich- Thanks for the reply! To address some of the things you mentioned...

With 800FWHP, I was kind of hoping for about 650, maybe 675 at the wheels. I think this should be possible with the built 700R4 that I have in the car now.
I think I will end up doing this with the walbro 255's then. I will probably do the mod where you use the EVAP line as a supply line and use a Y adapter to convert into 1 -8AN supply.

I agree but here is the problem with that. I couldn't find a bypass style EFI regulator with a -8 feed...they are all -6. Maybe I need to look at companies other than Aeromotive?

I don't plan on using E85 at all. I only mentioned this because I have read that the Walbro pump for E85 supposedly flows about 430lph. But that is flow for E85. I am curious to know what it will flow if 93 octane is used because 430 lph is good for a tick over 1000hp.

I may have to wait until the system is fully installed and see where the best place for it will be.

Can you clarify this statement? Do you mean that it will cause engine damage or that it will make too much power at higher RPM?

As much of a street car as possible. Honestly, I haven't seen any large turbos up close and it is hard to gauge the size by pictures on the internet. I would prefer to go with the absolute smallest turbo (meaning overall physical size) possible that can meet my horsepower goal without being pushed to the point that it either generates too much heat in the intake charge or risks surging and coming apart. I may call the Forced Inductions place you mentioned and have a chat with them and see what they say regarding my setup. Thanks again!

Orr89RocZ

iTrader: (20)

I like single plane intake with good elbow. Smooth radius 90 deg

Dual walbros are fine. I make 1009 whp thru a th400 and may have a bit more left. One on hobbs is fine but could put them on all the time, or on a wot switch.

Cam, something in the 224 range, single pattern on a 112-113 is great. 230 deg would be ok if you want to turn 6200 ish rpms peaks but dont need to.

I agree bigger turbine would be nicer but should work. That 7675 would spool fast but start to become a restriction as rpms increased. Still should make enough steam tho. S400 stuff you could grow into but its a huge frame to fit.
78-82mm would be a better compressor size and offer more room in case you wanna grow more.

80 lb injectors would be preferred.
-8 supply -6 return. Alls well

Jay_rich

iTrader: (4)

Oops sorry I thought you said 850whp. Then in that case dual 255s.

Im pretty sure aeromotive makes a -8an version. I had the -6an version and just used -8an fittings on it. Obviously not ideal but I had it...if not im sure holley or magna makes one.

Also 80# injectors will do that trick at that power level on gas.

Like orr said. Up top that turbo will choke the motor out. You are gonna want a big exhaust wheel with those cubes. You could even look into the s480 t4 flanged if space is a concern

Jay

Orr89RocZ

iTrader: (20)

Pt8047 looks nice. Alittle larger turbine wheel and compressor. Think it fits a 383 better. But you dont need alot to do 650-700 whp

paulmoore

Definitely appreciate all the info guys! I have a lot of things to look into and do research on. On a side note, Orr, I see that you live in Pittsburgh, PA. Whereabouts, if you don't mind me asking. I used to live in Morningside near the Pittsburgh Zoo, then moved across the river to Sharpsburgh, then north to the Tarentum/New Kensington area.

Anyways, back to topic. Do you think that either of those turbos that you recommended, the S400 style or PT8047 would fit in the drivers side front area where the charcoal canister sits? I would like to keep the battery in the original location if possible, but if I have to move it to the rear then so be it.

Jay_rich

iTrader: (4)

I would assume so. My very first build I stuck a T6 turbo in the passenger side area. Just simply moved the battery to the other side. Both sides have tie downs for the battery. So all I had to do is run a new starter and alternator wire. It was just easier on this side since the way the flange sits.

Jay

Orr89RocZ

iTrader: (20)

My buddy ran a gt4202 on a ls1 370" motor and made 811whp but was working that turbo pretty hard. It was only a 74mm comp but did the job. Would fit in the engine bay tho being a T4 frame. Something like that also could work. Any of the turbos mentioned would do the job

I'm 30 min south east of Pittsburgh in greensburg

paulmoore

Ok. I called around some more and the last person I talked to was Joseph over at Forced Inductons. We talked about my setup and what my plans were. He suggested using an S400 turbo with the T6 flange, 92mm turbine wheel, 76mm compressor wheel with a 1.1 A/R housing. This turbo seems to be the one that everyone is recommending to me based on the cubic inches and the usage. Seeing as how this is a street car mostly, the thought is to keep the exhaust turbine bigger so that the turbo won't make any boost while at cruising speed or (light) part throttle.

I did some more research on some stuff and came across a wealth of info over at LS1tech.com, where I am also a member. I stumbled across this post in particular...
http://ls1tech.com/forums/forced-ind...over-pipe.html

Using some of the info in the above post I researched the size of the T6 flange and found the info to be credible. Assuming that the T6 flange is in fact a divided flange, then 2.25 inch pipe is almost the exact same size as each flange division. That being said, here are my thoughts...

I will use my Dyno Don shorty headers as turbo manifolds. They have 1 3/4 primaries and a 2.5in collector. I will cut off the ball flange and weld on a 2.5in to 2.25in reducer, and then run one 2.25in pipe from each collector to the T6 inlet flange on the turbo. This should maintain extremely high exhaust gas velocity and allow for better turbo spool up time and overall efficiency.

Unless I missed something?

On a side note. Does the turbo hot side tubing have to be stainless? I know that most of the turbo manifolds out there are stainless steel as well as the crossover pipes. What is wrong with using regular mandrel bent steel tubing? Is it from a heat retention standpoint, or the fact that SS doesn't tend to corrode? Maybe higher pressure/heat thresholds? Someone enlighten me!

Also, what worries me the most about this turbo is finding the room for a 5 inch downpipe. I do have a tubular k frame and control arms, but with the turbo itself being rather large, plus the routing of the crossover pipes, I am not sure I can get a 5 inch downpipe all the way out of the engine bay. Would it be possible to neck it down to 4 inches as it gets closer to the a/c box area to transition it to the rest of the exhaust?

Orr89RocZ

iTrader: (20)

Yup that turbo will work for your plans. Should still spool well.
2.25" feeds is perfect. Will maintain velocity thats for sure.
Mild steel is fine just tends to rust/corrode compared to stainless. I would wrap the pipes in header wrap for heat management and better response
Can neck downpipe down to 4" or split into dual 3" if needed to make pipe routing easier

paulmoore

What about a ceramic coating like Jet Hot or something similar? I figured that I could essentially get the piping all fabricated and send the tubes off to get coated inside and outside. The coating should keep the heat contained to the piping itself, which in turn keeps the heat in the exhaust gas itself. I am not doing it for looks, but for functionality. Maybe after the coating is done I could use a header wrap to seal the heat in even further, although, I have heard the horror stories about header wrap and how the pipes start rusting from the inside out.

Maybe the stainless would be cheaper in the long run?

Orr89RocZ

iTrader: (20)

The ultra high temp stuff should work but its not cheap from what i remember. Shorty headers were 300$ to coat like 7 years ago

I would just wrap since headers are going to be mild anyway i believe. Dyno dons mild and ceramic coated?

83 Crossfire TA

iTrader: (2)

A real GT4202 should be a T6 frame, but who knows what you get when you buy from a lot of aftermarket vendors. What size/ar exhaust did he have

I'll go a little different on a lot of the things said here, but you'll be fine with what has been recommended, mostly because you won't need to go quite as big with things to get to 850bhp, which is a 2 sided sword: on the one hand you'll have a more fun street car with smaller parts, but once people start pushing boost there is a tenancy to turn it up and want more, so parts with room to grow aren't a bad idea if that is might be the case. That said, you won't need as much turbo or cam to get there, but heck, if you wanted to keep your current cam, it would be all wrong and you'd still be able to make that power.

Your injector calculation, (HP x BSFC)/cylinders will generally work, and .65 is plenty there but you don't have any adjustment for maximum duty cycle (typically people will do something like divide by .80 to prevent going over an 80% duty cycle). Really a BSFC of .65 is higher than what would be a good number, so you _really_ shouldn't use that much fuel, but real world, people use fuel to cover up other problems/safety so eh, if you have the 65's already then try them, with good tuning they should work, if you don't they 80's cost almost the same, it doesn't really make sense to get 65's.