scandavid

I have a 1987 Chevy Camaro that I have completely restored from the ground up. I built the whole car up around the engine and now I have saved the engine build for last. I am building a twin turbo 383. The parts I have bought so far:

• Stock LT1 block splayed 4 bolt main
• Fully forged Scat rotating assembly
• Twin Garrett 60mm turbos and headers
• Godspeed intercooler and all the plumbing
• T56 Transmission

I’m trying to get some suggestions and tips on what might be better or things I should get that would help. I’m open for all opinions and peoples past experiences to help me do this right. One thing I am not trying to do is cut corners. I have the money to do this right so that’s what I’m going to do. I want to run mega squirt for my fuel management. I plan on running 9.5:1 compression and around 12 lbs of boost. Let me know if anyone has any questions or suggestions. Thanks

Orr89RocZ

iTrader: (20)

Get a good turbo cam and ported LT1 heads...probably best to go aftermarket to get larger chambers as most ported LT1 heads are in the 54-56cc range and that combined with a 3.75 stroke will make it hard to keep compression below 9.5 to 1. With 54cc and JE pistons -28cc dish, you can hit 9.6 to 1 but I'd like to see below 9.5 to 1. If the heads dont need to be decked and you are at 56-58cc maybe have a chance to use them. 12psi on pump gas 9.4 to 1 will work fine.

60mm turbos will be perfect for that build. I ran a set of 60's T4 frame on my 401 and it ran 10.0's at 138 on 12 psi. 9.86 was best so far on 14 psi.

Now you just need to plumb the system together. Figure out where to mount things for best clearance, especially around the header bolts and spark plugs. I didnt design my setup that well with clearance in mind...hence install and tear downs are a PITA. Mainly on the driver side since its the tightest spot but even passenger side is a PITA at times.

Another suggestion is to heat shield and insulate the engine bay from the heat turbo setups put out. I used some of the double aluminum foil sided matting for alot of the engine bay, got some wire sheild wraps, wrapped the downpipe and headers, turbo blankets, etc and it helps greatly with isolating heat from important stuff under the hood.

Thats really all there is to it. More specs on the turbos? I'd use a T4 if possible but a large wheel T3/t4 hybrid could work. You have more than enough compressor to make 800hp.

scandavid

okay thats a lot of good info thanks. What do you mean by t4 frame? I have the stock lt1 aluminum heads. Should I try to make those work or should I just go with some brand new ones? Roller rocker valve train im assuming too right? What would be a good cam range for a turbo setup?

Orr89RocZ

iTrader: (20)

T4 inlet flange size on the turbine exhaust housing. Usually a P trim type turbine wheel, 64mm/74mm size

Depending on your power goals you can try to get the LT1's work. I'd get them ported and have them mill the deck the thinnest they can to ensure smooth flat surface...they are 58cc to begin with you dont want to get too low or you wont get your compression down. 28cc dish with 56cc is 9.4 to 1 which is good.

Depends on what casting you have too, as some are more desireable for porting than others. For a 383 i'd open them up as much as you can... Lloyd elliott stage 2 atleast or Advanced induction or maybe even Total Engine Airflow. Else if you have the budget get a set of aftermarket heads..but thats pricey.

If you dont care to make too much power you can use the stock heads but it will limit power and rpm.

For a cam, if you port the heads i'd have them recommend a grind, but for a 383 i'd try something close to 228-230 deg on both lobes, mid 500's lift on a 112-113 lsa.

yes full roller valvetrain is nice to have but you could get away with just roller tip designs. Really should get a good set of steel full rollers as they are stronger. For a decent cam turning 6000 rpm, you will need to have a good 155# double spring in the heads to control the valves under boost, and those springs are usually close to if not over 400# open pressure. I'd trust a steel rocker for that.

Can use LS7 lifters.

12 psi should easily make 600whp with good heads. Probably closer to 650 on a dyno jet. I made 640 on 12.5 on a mustang dyno running thru a loose converter and a tad on the rich side. I can see 700 on my setup on a dyno jet with more tuning

Keep in mind the T56 will need a good rebuild. It will stand up to the power but to too many clutch drops and such unless the clutch is somewhat slippy

scandavid

okay yea i have the t4 flanges already. So your saying if i can i should do a full roller valve train and cam set up but if not just the roller valve train will work. When you say 155 do you mean the O.D. of the valve or the seat load? Another concern of mine is should it be hydraulic or solid lifters? The ls7 lifters will fit my block if I order some new ones? Whats a good set of heads that are worth the money in your mind? Is mega squirt a good fuel management to go with? What are you running on yours? I didnt understand what you were talking about with the t56? I plan on rebuilding it and putting a nice clutch and flywheel in it.
Thanks

Orr89RocZ

iTrader: (20)

For valve train, you should try to get rockers that have roller tips and roller body, aka full roller. Stuff like Comp cams pro magnum rockers. You could run the aluminum versions too, like harland sharps, etc. I like steel tho.

155 as in 155 lbs of pressure on the seat. Valvesprings have install height of x.xx inches. The pressure at the seat is given, and there should be a spring rate in lbs per inch and an open pressure at max recommended lift. Most modern hydraulic rollers with some amount of boost from a blower/turbo etc should have 150lbs on the seat and over 370 open IMO. I run 165lbs seat and 412 open. Factory AFR 8019 springs on my heads that are shimmed abit.
Alot of manufactures make strong small diameter double springs with rates like that. Beehives would work well too. Depends on how much rpm you want to run

I think you should stick with hydraulic roller cam for ease of operation and maintenance.
LS7 lifters will work fine with the LT1.

If you have the good head castings they can be ported. I'd have someone port those heads... best bang for the buck really. Lloyd Elliott is one guy who can do it. Advanced Induction is another place. Those are the 2 best that I know of that have great results. BUT they only work with certain casting numbers. I think heads on the 95-97 LT1's are most desireable.

Else you could try trickflow TEA ported LT1's from Total Engine Air Flow. AFR could work fine. Dart makes a nice 180cc head that can work well, but i'd port them alittle to get a better cross section and port size for a twin turbo 383. They arent cheap either I'd rather see you go TEA trickflow or AFR for the price. AFtermarket heads tho are very pricey for LT1's regardless if you go AFR, Trickflow, Dart..etc

http://elliottsportworks.com/home/?page_id=53
http://www.totalengineairflow.com/pr.../gmhead/gmlt1/
http://www.totalengineairflow.com/pr...gmhead/tfslt1/
http://www.jegs.com/i/Dart/301/11111...oductId=932783

I run stock 91-92 ecm with code $59 which is just modded GMC syclone/typhoon turbo truck code. For an LT1 you can use stock ECM probably from LT1 4th gen or maybe megasquirt or an OBDII LS1 setup.

scandavid

Okay this is great info thanks a lot. If you could touch on the fuel management a little more I would really appreciate it because would I get the stock ecm from a lt1 4th gen and then get a piggy back system or would i send my ecm out to get it flashed or something? what is the easiest but would work the best? What size injectors did you run when you ran your twin 60mm?

Orr89RocZ

iTrader: (20)

I am not too familar with LT1 PCM setups. I think you can program them to accept a 2 or 3 bar map sensor like the LS1 cars. If you can do that, then thats the best bet. You can get a flash mail order tune that will probably get that car running somewhat smoothly for idle, cruise and medium part throttle, but definately not for boosted situations. That would be a good place to start tho. You or someone familiar with LT1's will have to look at tuning it.

For my setup I run 80 lb rated injectors, by Siemens. Rated at 43.5 psi standard fuel pressure and I run 46 or so. I will be bumping it up to 50+ since I think I'm already approaching 85% cycle duty which doesnt make too much sense to me based on the power I put out but thats what the computer is telling me.

scandavid

I think im going to run the LT1 ecm and then use the megasquirt III system on top of that. Then Im going to get rid of the old wiring harness and get this simple fuel injection wiring harness.

http://cgi.ebay.com/ebaymotors/1994-...#ht_1199wt_939

But im still a little confused on how to delete the opti spark system. Do you have any experience with that?

Orr89RocZ

iTrader: (20)

Nope, havent done that.

scandavid

You still run the opti spark?

Orr89RocZ

iTrader: (20)

I use a gen I sbc with 91-92 camaro system. Its a distributor like any other sbc. I never had an LT1 car

ZZ3Astro

With a Megasquirt 3 (MS3 with MS3X) you could run coil per cylinder and sequential injection. It will set you back about $650 plus a harness build ($65 + $78 for diy, not including end connectors). That would be a sweet way of elimating Opti-arc! :-)

scandavid

Well what sensor would you use to tell the coils where the crank is? Do you use the stock ecu with the mega squirt? What is your set up?

scandavid

Orr89RocZ, what rear end are you using?

Orr89RocZ

iTrader: (20)

stock 10 bolt from a 99-02 4th gen. Zexel Torsen diff, 2.73 gear

Orr89RocZ

iTrader: (20)

I think they put a ring on the crank snout and read that. They make a conversion kit for sbc's to use LS1 style electronics and they put the ring on the crank.

scandavid

Wow, why such a low gear like that to get traction or something?

ZZ3Astro

Right now I'm running a megasquirt II standalone. It handles everything including boost control and fans. I could have it control the converter lockup but I chose to keep that manual.

For doing sequential injection and/or coil per cylinder, you would have to come up with some type of crank position sensor. There are plenty of sources these days for ones that bolt between you pulley and harmonic balancer. DIYautotune has several sizes around $30. Then you'd have to fab up some sort of bracket to hold the sensor. If you were running a vortec engine you could use the factory one inside the timing chain cover. Pretty much however you want to do it, the megasquirt will work with it. Of course you'll still have to run the bottom part of a distributor to keep the oil pump going. And I'm not sure what requirements there are for sending a cam position to it.. haven't researched that far yet!

As for your question on Orr's gear ratio... If you're running a TT 383 I think you'll find anything lower than about a 3.08 is too much gear! Turbos like to be loaded and make plenty of torque so you'll never regret getting rid of that 3.73 or 4.10. Also as Orr is finding, those higher gear ratios seem to hold up a lot longer to abuse.

scandavid

Are you running a distributor or individual coils?

Orr89RocZ

iTrader: (20)

What ZZ3Astro said. 141mph on a 26 inch tire is about 5000 rpm before torque converter slip..which can be 3-8% depending on how its built. Mine I think is in the 3-5% range. My motor peaks in the mid 5000 rpm range so its actually almost optimal to run 2.73 gear. I may go to a fab 9" setup with 2.91's when I upgrade, or if I do 12 bolt I will go 3.08 and run abit taller tire perhaps

You will find with 500+whp, it doesnt matter what gear you have...the power will overcome the lack gear, and really overcome the tires I can light them up from a 50 roll in 3rd gear with these 2.73's. Its ridiculous.

And yes, the turbos like a loaded motor.

ZZ3Astro

For now I'm running the stock ignition setup, controlled by the MS2 and powered by an MSD 6AL.

At some point I will be going to the new MS3 and converting to coil per cylinder and sequential.

scandavid

Why are you going to convert to that? Do you already know what you would need to make it coil per cylinder and sequential besides the MS3?

ZZ3Astro

What I have works pretty well, but I'd like to low mount the coils so you don't see any plug wires. Plus routing the wires down keeps them away from the heat, which is quite brutal at times with a turbp blocking the exit! And of course the engine bay is cluttered enough as it is. Other than that, I figure if the manufacturers have switched to it, there must be an improvement in efficiency and/or power. Plus there is something cool about being able to say I have a sequential injection turbo TPI! Must be the geek in me!

I actually can do coil per cylinder with the MS2 but I'd have to add some other hardware to do it. Instead I would just upgrade to the new MS3+MS3X and make a whole new harness again so everything looks nice and clean. You'd be adding quite a few wires since each coil and injector would be individually wired to the MS. For coils I would use whatever LSx coils look the best for this application.

daverr

iTrader: (1)

Having that low of a gear makes the car boring on the street. And launch like a school bus at the track.

To mask a traction issue thru gearing is like spitting in the wind. Start investing time and effort into your chassis.

ZZ3Astro

Not with 600 ft lbs of torque!

calebzman

iTrader: (3)

With a T56, I wouldn't ever want to run something as low as a 2.73. I tried a 3.27 and I much prefer the 3.70 I have now. With the smaller turbo, I still make full boost in 1st gear.

Orr89RocZ

iTrader: (20)

Theres only so much you can do on a street/strip car to gain traction. Short of a full tub out back, you will have live with some lack of traction but certainly the low gears are NOT boring on the street and are not an attempt to mask traction issues. I gear/tire the car for the 1/4 mile and it just happens to work out that 2.73's arent bad for my combination of parts. Its been 1.49 60 foot on the foot brake with no boost on launch. If I had boost or a transbrake it be pulling wheels and goin low 1.3's easily.

For a T56, you could go higher but still need to shift to 5th gear in the 1/4 with a gear steeper than 3.23/3.27 on my setup. Not optimal but doable I suppose. the overdrives were not meant to be pulling gears.

Shadow Z

iTrader: (2)

I have to agree, 2.73 is a bit low for a T56, they have pretty low gearing, especially first and second.

I'm picking up a T56 out of an 03-04 Cobra for my '01 GT since I just about destroyed the 2nd gear synchro, and even with my 3.73s, the top end possibilities are insane with the T56.

With my 285/35/18s, 3.73 gears, and a T56 @ 6,000 RPM:

1st - 46 MPH

2nd - 69 MPH

3rd - 95 MPH

4th - 123 MPH

5th - 156 MPH

6th - 196 MPH

I shift at 5,600 though, which is right around where power starts to drop off on a 2V 4.6, so the speeds I achieve in each gear are a couple MPH slower.

I really want a T56 for the IROC, but I figured I'd keep the 700R4. It'll be useful for "manual vs. automatic" arguments, I own both. On that note, this seems to be an interesting thread, I'll have to keep an eye on it. Good luck with your 383 build, OP.

Orr89RocZ

iTrader: (20)

You can always run taller tires at the track if you need them and then on the street use the typical 26" tall size tire. That way you can have optimal gearing for both conditions.

scandavid

Okay that sounds a little better. I have a question about the for 9 inch, what type of rims do you run since your wheel offset is different front and back? I have an opportunity to buy a ford 9 inch for 300 dollars and it comes with 3.70 gears in it and has the 31 spline axles already in it. Should i buy that or just stay with the 10 bolt and get beefy axles and gear?

Orr89RocZ

iTrader: (20)

is it a 9" designed to bolt into a thirdgen? If not you will not have spring perches, torque arm mounts, lower control arm mounts etc... it wont work.

scandavid

no its a ford 9inch and you cut all your old mounts off the 10 bolt and weld them on the 9 inch and then for the torque arm Currie makes a ford 9inch torque arm mount just for the camaros. Can a third gen 10 bolt handle power if you put after-market axles and gears in it? If so I would much rather keep it but i dont want to put money into the 10 bolt and then have something break.

Orr89RocZ

iTrader: (20)

Yeah I guess you can just build it up as long as the width is right.

With a t56 and pretty aggressive driving and ~600whp i'd say the 10 bolt will not be happy. Its usually the ring gears and carrier that fail before the axles do.

You can put all those parts in with C-clip elminators and such but if you try to push the performance limit with a quick clutch slip or even a drop, I think it will hurt the rear fairly quickly.
If you roll out of the throttle and not leave the line at the dragstrip under boost and sticky tires, dont powershift, and run a thicker gear set that 3.08's and below have, you may get it to live. I have been very impressed with my setup but the auto/stall setup softens the hit to the rear alot more than any Clutch slip setup would.

If you trust your fab work and can do the 9" conversion, definately go that direction. Run the 3.70's for awhile. it will be kinda fun on the street when it hooks up at higher speeds and at the track depending on the boost level, you can try a 28" tire and still
trap 139.5 mph in 4th gear at 6200 rpm... that should be 14-16 psi on a 383 depending on how stout you build it and vehicle weight/track conditions/etc

scandavid

Orr89RocZ, what size injectors should i run 60 or 80lb?

Orr89RocZ

iTrader: (20)

how high do you want to push things? 60's will work for most things up to probably 600whp at normal fuel pressure. Crank up the pressure to LSx levels of 58-60psi and they act like 70lb injectors which should handle near 775 hp.
If you start getting the boost up in the 15+ psi range on a 383 with good ported heads and decent cam, you could start making some big hp. You'd definately have the turbo to produce over 800hp if the heads/cam are decent sized.
I'd go 80's if you want to run much over 650-700whp but then the block may become an issue. The 80's from siemens are great injectors, they behave nicely even with lower pulse widths. I'd recommend them for a 500-700whp build with lots of room to grow. Else 60's on high pressure should do most of the work.

I believe some injector guys have 70-72's which are just modded 60's designed to flow 70lb/hr at 43.5 psi. Otherwise just get 60lb injectors rated at 43.5 psi and run 60psi fuel pressure like the LSx guys do.

scandavid

okay. To tell you a little more in depth on what i have now, I have brodix aluminum heads, comp cam dual spring valve springs, crane roller rockers, crane race hydro roller lifters, comp cam custom grind cam with 230 degrees both sides, a stealth ram intake manifold and scat forged rotating assembly. Do you think that stuff with flow pretty nice?

Orr89RocZ

iTrader: (20)

you putting together an LT1 as in GEN II motor or LT-1 1970's block? Stealth ram isnt for an LT1 unless you mod it to fit which isnt that hard to do. Just trying to clarify things here...

what size brodix heads...if they are 200 cc or so they shall be great on a turbo motor. Stealth ram should work, others have used similar intakes before. I got rid of mine because I feared distribution issues under boost. I went to a single plane EFI setup and it seems to have equal air distribution. I really liked the HSR tho

Valvesprings should be pretty stout for the boosted setups. Most guys I've talked to recommended 10-20 lbs seat pressure extra over what you would run on a n/a motor. A more aggressive cam may want 140-150 at seat for n/a but with 15 psi acting on it, you will need abit more spring..160-170 lbs seat with 380-400-ish open. Just my recommendation to prevent valve float. Cam lobes for turbos are usually not all that aggressive tho.

Shadow Z

iTrader: (2)

Even more impressive. These build threads make me sad. I let the IROC just sit around, and put my $ into the Mustang since it's the newer car with less miles.

Some day, an Eagle 383 stroker kit will be mine.

scamaro355

watching this one close :~)

sailtexas186548

iTrader: (2)

you really don;t want to use 5th and 6th as "performance gears", they are not designed to be abused and tend to break in high HP cars. the car's doing big MPH in events like the mile are using tall tires and 2.xx rear gears so they can stay out of 5th gears and still do 200+mph. they also run auxiliary pumps to keep 1st through 4th lubricated

Shadow Z

iTrader: (2)

http://www.webridestv.com/videos/svt...s-police-53083

Shadow Z

iTrader: (2)

On that note, I'm aware, and have never even attempted to pull in 5th, mainly because I can do 120+ in 4th. However, I wouldn't abuse my Mustang's stock TR3650 that bad by going for 125 to whatever it has the power to do in 5th, probably would be out of breath at 150.

I'm not Mr. rich guy, but this year I'm having a T56 built properly. I'm picking up an 03-04 Cobra T56 this weekend, and having a Viper spec rebuild done at Tick performance in the fall. It's recommended for builds exceeding 600 LB-FT of torque, so it'll handle my little GT. I'm making maybe 270 torque at the wheels, and probably right around 240 RWHP. That's just what I've seen other cars do with similar mods, Bama tunes, a CAI, catback.

Might free up some more power hopefully. I just ordered myself some new custom tunes from Bama tuning. 87 street tune, 89 performance tune, and a 93 octane race tune for an offroad X pipe. One of my cats of cracked, and is most likely clogged, so I've always wanted to try this neat little product out.



"But officer, look, I have catalytic converters!"

Geez, I need to buy a T56 for the IROC too, just to keep this on the topic of F bodies.

calebzman

iTrader: (3)

I was just reading a car craft article where they put a 90mm turbo on a LSx, and with 60lb injectors they ran out of injector at just over 900hp. This seems to agree with the calculations for injector size vs hp.

Orr89RocZ

iTrader: (20)

My buddy used 60lb injectors on 58psi on a single 88mm 4.8L lsx and made just over 700whp and was pushing 100% cycle duty but it was abit on the rich side, but safe tune. They were 60lb rated at 43.5 so on 58 they are closer to 69-70.

That was thru a T56 and a 14bolt rear end (truck). I didnt think they could go anywhere near 900hp unless 900 will translate to 700whp but I dont think so. I guess it depends on the actual fuel pressure and how efficient the motor is. I dont know the reason for the 80% cycle duty rule, but I dont want to go above that to far.

scandavid

no its the LT1 gen IV out of a 95 camaro. The heads are 200cc, yea im getting some real stout valve springs

1bdbrd

iTrader: (1)

I'm a little late with this answer but as of a couple years ago the LT1 PCM couldn't handle more than a 1 bar map sensor. Someone may have gotten around that with clever trickery but as of then they hadn't. My friend that ran into that also went 10.8@128 on 11lbs in a mostly full weight lt1 formula with a 355 lt1. It had a stock crank, budget billet rods and forged pistons. Stock heads with upgraded springs, stock cam, roller rockers and a stock intake with the stock 48mm tb. Turbo was a Turbonetics TC76 and was backed by a th400 and stock 10 bolt. He tried to run more than 11lbs but the stock ecu just wouldn't cut it and it had real bad ignition problems which held him back. I got a ride in the car and on 10lbs it rolled out real good!

scandavid

thats why you run megasquirt fuel management not a stock pcm.

1bdbrd

iTrader: (1)

There wasn't an option then for full standalone for an lt1 then. Plus it also wouldn't drive the stock gauges. He considered it before he parted and sold the car instead.

IMO the best option is the LS1 ecu conversion. Its way more expensive but I just like the outlook of it more than megasquirt.

scandavid

Quick question, I just picked up the HSR (holley stealth ram) and was wondering if I could use the stock fuel rails? If not what is an affordable alternative fuel rail that someone has had good success with? I also was reading about putting fuel rails in parallel instead of series, is that a must or what?