Need Experienced Turbo Users Help

[79TransAm]

I'll start off by saying i know very little about turbos, so pls dumb down your language as much as possible, or just define if possible.

I'm planning a build for the 79... im looking for like 650ft/lb tq and 600hp. I'm planning on stroking a 455. This is the kit im looking at. 474"]http://gallery.bcentral.com/GID4716958P1571498-Rotating-Assemblies/Balanced-Rotating-Assembly-Converts-455-to-474.aspx)]474 Stroker Kit[/URL] Gonna get 114cc heads from like a 75ish 455(hopefully will have them on it when i buy the engine.) I'm trying to find out from pontiaction what the approx. cr will be with their pistons and these heads. Plan on doing cams and what not... Now I want to throw a turbo on it as well. I might end up just turboing a 400ci instead so if anyone could give me opinions on each that would be great. Here is what a turbo calculator said would be good for the 474ci engine:
Garrett T42
Engine Capacity 474ci(7800cc)
Maximum RPM 6000 rpm
Boost Level 6psi
HP Rating 800
Non Intercooled
Turbine Hsg A/R 1.22
Airflow Lb/min 65.29
Base HP 709

It probably wont be around 700hp im aiming for like 650ish hp/tq. I'm buying a keisler automotive 5 spd that will handle 650ft/lb tq. My questions are bout how much will this turbo raise my cr at only 6psi. would you reccomend a FMIC? I read that with this low boost i can run like a stock eclipse BOV, but id have to do something bout the wastegate. Do you think this is a suitable size turbo for this engine or will it create massive lag, should i got with something a little smaller. I can probably find a turbo off a ford 7.3L diesel and make it work(in order to lower cost). any info anyone could help me out with would be great. The engine probably wont be built for atleast 1 - 1-1/2 years since im doing the suspension and interior first, but i just wanna have everything figured out, thanx in advance.

im looking at a couple turbos on this site, what does anyone think of these?

Turbo Options



Looking mainly at the Master Power T62 Turbo T3 .96 A/R Turbine Housing for $700 which doesnt seem like a bad price, would you reccomend T3 or T4 flange, and whats the difference?

[TurboLark]

First off..you DO NOT want to use a t3/t4 hybrid on that motor. Way too many cubes for the tiny t3 turbine housing.
The bigest obstacle to overcome is the 600hp at low boost, and still have an efficient compressor side. I was originally thinking master power t-70, but it isnt quite right at only 10lbs of boost. I need to find my compressor maps for the GT-42, but it looks like it may work great for you. Another turbo that is very common, and should work great for you is the Garrett T-76 with the .96 turbine. That would probably be my choice. I think you could reach you hp goals without having to do a big stroker. The 400 or 455 would be just fine, plus allow for more "normal" sized turbine housings, like a .96 instead of 1.15 or 1.22.
I would use a FMIC even at 6lbs of boost, but I would suggest around 10-12lbs on a more basic engine(can save a ton of money that way). Buy a good blowoff valve like the Tial for around 225.00. The eclipse isnt very big and will not do the job properly. And for the wastegate remember, big turbo + low boost= larger wastegate needed(you bypass alot more exhaust in this situation).

[70ptta]

79transam what manifolds you going to use

[Travis B]

You could get 600hp and 650tq out of NA 455 or 474 with no porblem and have good street manners as well! If you are just after the wow factor then fine but that power could easily be obtained NA

[79TransAm]

i think im gonna just stick with a 400ci bore it .040 over. Run approx 10psi. For the exhaust manifolds i might end up using the early 70's stock cast iron. it doesnt flow as well but it will be easier to route the pipes as opposed to running long tube headers. if you got a suggestion for this problem it would be greatly appreciated. If i use the 400ci (which i will) I can get 455 heads with 114cc that will run about approx 7.3:1 cr with flattop pistons, that way i can hit the boost to like 10lbs and still run pump gas. any suggestion on whose FMIC to use? I can wait till this cars done its gonna be wicked. Its gonna be mainly street use with a little track time. I'd like to street course race it eventually but not like every weekend. I'm just looking to build a pro touring style crusier. thanx again for the info.

[xxxturbo6]

I have a little knowledge on turbo buicks and alot of turbo specs and info If I can, i'll try to answer any qwestions you may have. but I can tell you this! on a turbo car you DO NOT need a large cam cause most of your power is coming from the turbo and also the right stall converter for the turbo you will be useing. then have enough fuel to supply the boost level. and a Percision FMIC to cool the inlet air, and a large exhaust to get rid of the air that the turbo generates. please contact me for any qwestions you may have. scot w.

[79TransAm]

heres what i was thinking... Pls give me opinions on my selection and pls let me know if you know of a better product or company.

Holley Street Avenger 870CFM
Edelbrock Performer RPM
400 Bored .040
114cc 455 Heads Ported And Polished
Forged Internals
Comp Cams Cam(Not Sure Specs: But I think its supposed to be low dur high lift?)
Garrett GT40 Turbo Compressor Housing 88mm 54 Trim, .72A/R | Turbine Housing 73 Trim, .94 A/R Pushing 10PSI
3" Turbo Piping
27.5 x 12 x 3 Spearco FMIC
Tial 40mm Wastegate
3" Pypes Header Back X Pipe Exhaust

[TurboLark]

heres what i was thinking... Pls give me opinions on my selection and pls let me know if you know of a better product or company.

Holley Street Avenger 870CFM
Edelbrock Performer RPM
400 Bored .040
114cc 455 Heads Ported And Polished
Forged Internals
Comp Cams Cam(Not Sure Specs: But I think its supposed to be low dur high lift?)
Garrett GT40 Turbo Compressor Housing 88mm 54 Trim, .72A/R | Turbine Housing 73 Trim, .94 A/R Pushing 10PSI
3" Turbo Piping
27.5 x 12 x 3 Spearco FMIC
Tial 40mm Wastegate
3" Pypes Header Back X Pipe Exhaust

Carb is too big. Just find an old 750 double pumper.
Cam should be low to negative overlap. I have a cam for my turbo 383 that has 236 and 242 duration with only a few degrees of overlap. For your hp goals you can go smaller than mine(I'm going for 1000hp). Get the cam with lift to complement the port work.
That turbo is too small. supports 650hp, which means it does a max of about 650hp. you will be needing alot more than 10lbs of boost to make your 600hp. Again, find a good used t76 and you will make 600hp easy, and have room to grow as you need to.
You only need 2.5" tubing from the headers to the turbo,then a single 3-3.5" off of it. Use 3" from the turbo to intercooler, and 3" from IC to the carb bonnet.
40mm wastegate is minimum, the 46mm would be better.
Use 3.55 gears or higher(3.00-3.25 would work well also).

[B&G CUSTOM TURBO]

Hi,
Stay with a t-4 flanged housing and preferably with 400 cubes go with a Masterpower 62-1 with a aftermarket .96 housing (or .81 for a faster spool and lower top end revs. You will have to run 18 PSI with a intercooler with a effecency of at least 60% or better. Use a holly 750 as you will flow 744 cfm at the given pressure

If you are going 455
You can also get away with the 62-1 (.96 exaust A/R) as you will only be using 13 psi of boost and it can supply the required 61.7 LBS per min. Use a 850 you will be flowing 840 cfm of air.

As stated above stick with a smaller cam with less duration, as anything bigger really won't be needed.

I would recommend a Tial 44MM wastegate, at the boost levels you will be running with the bigger housings it would be more then big enough.

I am a masterpower / precision/ garret dealer and specialize in custom headers for turbo charger applications. www.bgturbokits.com
www.bgturbokits.com/PICTURES

If there is some intrest I may even advertise here. I was pointed here by one of your board members who told me about your site.
I hope I helped you out a little,
Thanks,
Brian
B&G CUSTOM TURBO FABRICATIONS

[TurboLark]

Hi,
Stay with a t-4 flanged housing and preferably with 400 cubes go with a Masterpower 62-1 with a aftermarket .96 housing (or .81 for a faster spool and lower top end revs. You will have to run 18 PSI with a intercooler with a effecency of at least 60% or better. Use a holly 750 as you will flow 744 cfm at the given pressure

If you are going 455
You can also get away with the 62-1 (.96 exaust A/R) as you will only be using 13 psi of boost and it can supply the required 61.7 LBS per min. Use a 850 you will be flowing 840 cfm of air.

As stated above stick with a smaller cam with less duration, as anything bigger really won't be needed.

I would recommend a Tial 44MM wastegate, at the boost levels you will be running with the bigger housings it would be more then big enough.

I am a masterpower / precision/ garret dealer and specialize in custom headers for turbo charger applications. www.bgturbokits.com
www.bgturbokits.com/PICTURES

If there is some intrest I may even advertise here. I was pointed here by one of your board members who told me about your site.
I hope I helped you out a little,
Thanks,
Brian
B&G CUSTOM TURBO FABRICATIONS

Brian, the 62-1 flows around 62 lbs/min right? That would mean that at 600hp he will be maxed out with no room to grow, right?

[my72vette454]

I built a twin turbo setup on my vette last winter and can share a few things with you that I have learned. I used rajay 301e turbos with .8 a/r housings, tial 38mm wastegates and a 50 mm tial bov. I used an aeromotive a1000 pump with a 13204 aeromotive fuel pressure regulator and an old 750 holley dbl pumper that I modified for blowthrough. First off with the .8 housings, I start building boost at 2500 rpm and almost instantly have 12lbs by 3000 or so. I cant turn the boost down past 12 so I am assuming the gates are too small. The bov works great as does the fuel system. I dont have an intercooler on yet but plan on building one for next summer. There is definatly more power in the mornings when the air temps are cooler so I know an intercooler will help. From what I have read from others that have built turbo systems if you arent planning on running more that 10 lbs boost you might not really need an intercooler. You might consider a water/alky injection setup which would probably be cheaper than a cooler and those work good too and take up less room than a cooler would. This was my first experience with forced induction and damn its fun! Good luck with your car.

Mike

[79TransAm]

thanx so much for the info guys

[79TransAm]

thanx man. I was looking at getting a kit from snow performance. how do they work exactly, do they run open all the time or just when boost hits a certain level?

also what do you think about this cam?
Cam: RPM 2000-6000 DUR @ .050 INT-230 | EXH-230 Lift W/ 1.5 INT-.480 | EXH-.480 LSA110*

now this less valve overlap there is the high the LSA #?
Turbolark, what do you think bout this turbo?

Garrett MasterPower T70
Compressor Trim: .70 A/R
Turbine Trim: .68 A/R
also what would i have to do to modify to carb for blow through?

[TurboLark]

I would use aq cam with a wider lobe seperation. 110 is for naturally aspirated motors. Would have too much overlap for a turbo. You could use a smaller cam in the 400 to achieve the power you want.
You could probably use the 70 with good success. And they are relativly cheap.

[79TransAm]

what LSA would you reccomend? numerically higher than 110 or lower? I want to have the redline around 6k-6.5krpm. Is there any cam youd reccomend, or would i maybe have to get a custom grind cam?

[TurboLark]

what LSA would you reccomend? numerically higher than 110 or lower? I want to have the redline around 6k-6.5krpm. Is there any cam youd reccomend, or would i maybe have to get a custom grind cam?

I'd be looking at cams with 112-114 LSA.

[79TransAm]

k, cool thanx man
Hows this cam?: RPM 1800-5700 DUR @ .050: INT-230 | EXH-240 Lift With 1.65 Rockers: INT-.516 | EXH-.516 LSA 114*. Its the stock RA IV Cam. I figure ill be running with 1.5rr the lift will be lower.

[TurboLark]

k, cool thanx man
Hows this cam?: RPM 1800-5700 DUR @ .050: INT-230 | EXH-240 Lift With 1.65 Rockers: INT-.516 | EXH-.516 LSA 114*. Its the stock RA IV Cam. I figure ill be running with 1.5rr the lift will be lower.

You need to find out what the overlap is. Without that or the intake open and exhaust closing numbers you are kinda pissing in the wind. Turbo cam = very low to preferably no overlap. You need to pick lift for the head flow, duration for the rpm, and lobe seperation for no overlap. First 2 are easy, overlap is the harder one to find in an off-the-shelf cam.

[79TransAm]

alright thanx man, ill give comp cams a call see what info i can get.

[JLM]

I've got a few suggestions for you. Depending on what engine you end up with.

If you are going to run the 455 I wouldn't absolutely not run the thing past 5500rpm. Regardless of the internals you put in it. Stresses on the rods grow exponentially as RPM increases. Now add quite a bit of cylinder pressure to the mix.

for the 455 I would run a 4x head and a Performer intake (not an RPM) with something around an 068 cam which would be very mild for an NA 455 but would work rather well for a turbocharged application. Or a custom grind. Something around 230/236 @.050" on a 114-115 LSA would be good. Lift should be dependant on flow numbers for the heads. The poncho blocks weak link is in the lifter bores and when you start getting into radical cams with lots of lift you run into problems. Something around .490-.510 lift would likely be your best bet.

On the 400, you can get away with more rpm due to the better rod ratio and smaller stroke. On a 400 I'd run the Performer RPM manifold and probably go with the slightly smaller chambered 6x-4 heads. That'll give you compression between 8.0-8.5:1 on a 400 which will be more than adaquate to run about 15 psi on pump gas. 7.6:1 is just rediculous. The thing would be a turd in a short stroke 400 until the turbo/s spooled.

In both cases you might consider doing a magabrace on the lifter bores and filling the bottom of the block with block fill. The block fill will reduce engine coolant temperatures by about 10 degrees F plus add strength to the bottom end. It's been noted that oil temperature does not rise enough to even be seen in a guage with the block filled a little, but you can run an oil cooler (which will likely be a good idea with the turbo setup anyway) to cool the oil down.

What it really sounds like you are after is larger cubes but you also want an engine that will reliably rev to about 6000 at least. You might consider doing a 455 with a 400 crank. You'll end up with around 440 cubes but you'll have manors more like the high reving 400 than the low reving 455. You'll loose the torque benefit of the 455 on the low-end but the extra cubes will help to promote quicker spool from teh turbo/s.