Just started on the journey of fitting twin turbos to my small block chevy that's in my '80 Camaro.

Spent about 2.5 years rebuilding it from a rusted out hulk. Its currently got a 355 SBC which is putting out about 380hp. Enough to have some fun with, but I always like a bit of boost. Its got a 4.11 12 bolt with Moroso Brute Strength posi, steel shafts etc. Hood and front bumper cover are carbon/kevlar mix. 700r4 transmission with PATC Junior Raptor upgrades.

It's also running on Megasquirt EFI with a holley MPI manifold and 1000cfm throttle body. I made provision for a lot more power when I rebuilt the car, just needs bigger injectors and another fuel pump fitting at the back and it'll provide all the fuel it could need up to about 1000hp, not that I am planning anywhere near that.

(I've fitted hydroboost since the underhood shot was taken too!)

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So I am currently building up a short block with about 9:1CR (my current is 10.8:1) using a late 1 piece rear main, roller cam block. Got the block and a GM forged steel crank as a start. Plan on using my current Bowtie Phase 2 heads which have had a lot of porting work done. I just need rods and pistons to get the block built.

I've also already got the turbos and wastegates sitting on my bench. Turbos are a pair of T3/T4 hybrids, 38mm external wastegates.

Compressor:
Trim: 57
Exducer/Inducer: 76 / 50.5
A/R: 0.5
Turbine:
T3 Housing Flange, 11 Blades Type
Trim: 73
Exducer/Inducer: 65.5 / 55.9
A/R: 0.63

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Ordered a pair of front mount stainless headers/manifolds from SSAutoChrome and just waiting for those to arrive. I'll need to modify them to work with the external wastegates.

Ultimately I'd like to be making somewhere in the region of 600-650rwhp so it's being built with that in mind.

Oh we also have another project that might be up your street. Turbocharged, methanol powered bike thats currently on it's way to the USA to be run at Bonneville Speedweek with a land speed record firmly in our sights!

http://www.facebook.com/SaltFlash
http://saltflashracing.co.uk/

 

Good to see another 2nd gen getting force fed!
Is that a 2 bolt block then?
Also, you will definitely want to lower the gears cuz 4.11 is way tall for boosted cars. 3.08-3.55ish would be a better fit.
Im not 100% the headers will fit our cars, since I built my own, but I hesitated buying those since I worried about fitment. Twins will be easier for sure than my single build, the driverside downpipe will be a PITA tho. But you could fit 2.5" ok, maybe 3" idk tho with the hydroboost.
Keep us posted and good luck!

 

sounds like fun!!

 

looking forward to the build pictures

 

Nice!! Tons of room under those mile long hood of 2nd gen f-bodies. That 700r4 probably won't love life behind that motor though depending on how rough youll be on it lol.

 

Thanks guys.

Plan on fitting a 4L80E behind the blown motor with a Megashift controller.

The 1 pce rear main block is a 2 bolt, I'm not planning on spinning it too high, maybe 6250/6500rpm. If needs be I could always fit splayed caps. Plan on running ARP studs for mains and heads anyway. I have a set of 3.73 gears for the axle and plan on fitting those at some point. To be honest the 4.11 are a bit too low now with the 700r4 1st gear, makes launching difficult without tons of wheelspin.

No idea how it will work out for exhaust routing etc until I can mock up with headers and turbos. Hydroboost gives me a bit more clearance around that area. I reckon I am going to have to remake the subframe braces.

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Lots of work to do, and I still have a lot of parts to get, probably lots of questions on the way too I expect....

 

welcome to the forum, you're at the right place, tons of info here, nice looking ride btw

 

Your turbos may be a bit small, mine are similar, but 58mm, .60/.63 A/R, and I'm thinking about upsizing soon....

 

Thanks guys.

I've actually measured the compressor wheel tonight and its actually 54.2/70mm so it's actually a 60 trim wheel. Thought it looked bigger than 50mm. The hot side was correct.

 

Those turbos will be out of breath pretty much at your power goal... but theyll come online fast as shit!
As for the block, I would say splayed caps are a must for thst HP and boost. Hell, a 010 4 bolt will start to come apart in the 800hp neighborhood.
I say sell the 700R4 and put the cash towards the 4L80E before you're picking up trans guts off the street.

 

Couple more bits of progress today. The headers arrived, doesn't look too difficult to modify them to work with the external wastegates.

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And I collected a 4L80E too, just needs rebuilding and the output shaft and housing swapping for a 2wd version. Having looked at the parts it's easy to see why they will take so much more power than the 700r4. In hindsight I would have been better off just fitting one of those in the first place, but never mind!

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I am considering whether to go the whole hog and build the motor using a Dart block, certainly makes it future proof. Will see how the cash flow goes.

 

Just holesaw the collectors and weld a short tube to the gate flanges. You should slap those on and check for fitment. They seem like they'll hit the upper control arms or damn close to the point of melting the bushings.
I would try to find a 4 bolt 010 block and retrofit roller it, unless you plan on uber high HP for the dart block

 

Those are the same ebay headers on my car right now, for $160 to my door, I have no complaints whatsoever. The quality is surprisingly good with thick ass flanges.....my welder friend thought they were high dollar pieces before I told him they're ebay specials lol.

 

I put a set of headers like that on my truck and wish I would have built my own. I had to cut the flange off and extend the tubes 1.5" just to clear the power steering pump and the turbo hit the alt on the other side. But I have to say they have taken some abuse. They are on a mud truck so they see hot exhaust and then splashed with mud. No warping or cracking..... Yet.

 

So did you test fit those headers?

 

I've offered them up to my new block, but dont have any heads fitted to it. From what I can see it looks like it will clear the serpentine drive stuff (from a '90 G20). As soon as I have some spare cash I'll get started on getting the motor built up. We're off to Bonneville Speed Week with our bike this year and it's eating most of the money at the mo....

http://www.facebook.com/SaltFlash

http://www.saltflashracing.co.uk

 

Slow progress - time and money (mostly money) is the main constraint.

Spent an hour or so measuring the cylinder wall thicknesses on my block - was a little concerned as its at +.040. Measured all the wall thicknesses with calipers and a digital vernier in at least 3 places. I don't have ultrasonic measuring kit to hand!

They range from .161" to .212" on the thrust walls so I am happy with that. They are a little thinner on the front and rear (pin sides) but not enough to worry about. So I can now start getting the parts together for the short block. I basically need a set of splayed caps, rods and pistons along with a cam kit to have the block finished off. Got everything else I need.

 

Right, slight change of plan....

After some more research I've decided to go with some bigger turbos and waste gates from the outset. So after talking with SS Auto Chrome http://www.ssautochrome.com/ I've decided to go with some GT3582R turbos.

T4 frame with T3 mounting flange
.70 A/R Compressor
.82A/R Turbine
Compressor Wheel: 61.3 /82 mm
Turbine Wheel: 62 /67.8 mm

Hopefully these will be more suited to the sort of power I want to be making, and have a bit of head room should I want a bit more later on.

Along with that I've got a pair of 60mm v-band waste gates and a 50mm BOV on the way.

I'm just waiting to pick up a scrap cylinder head to use on my mock up engine then I can make a proper start on fabrication and modifications to the manifolds.

 

Lots of goodies arrived today! Fast shipping from SS Autochrome - from California to UK in 4 days. Wasn't expecting the best quality items, as I know turbos at this price can only be made in China but knowing that I'm impressed with the quality of the parts, packaging and service so far.

They came packaged as a pair

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These are the anti surge turbos with journal bearings. The compressor and turbine sizes are exactly as advertised - checked with a vernier. They are water cooled centre sections - not sure if I'll connect up a water supply to them or not - any reasons why it's needed? All of the bolts holding the housings to the centre section are stainless too. There's some radial play in the shafts, but no more than I'd expect.

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These are *exactly* the same turbos as sold by CX Racing - the part number on the boxes was TRB-GT35-2-P82, and the hot side has WSR Turbo cast into the housing

Next the 50mm BOV - packed in foam, 2 different springs ship with it along with a load of other accessories and a mounting flange with v-band. Also comes with a spare seal for the plunger. I've fitted the lowest pressure spring for the time being. The diaphragm is very thick heavy duty and nomex reinforced.

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Final goodies was a pair of 60mm wastegates. These have 4 springs with them for different boost levels from around 8 psi to something beyond silly and everything in between. Also have adjustable preload on the spring at the top. I'll be running electronic boost control through my ECU so I fitted the softest spring and bench tested with my compressor. They start to open at 8psi and fully open at 12 psi. I also have over boost protection on my ECU, so I'll be using that as a final safety device.

Again the diaphragm in these is heavy duty and nomex reinforced...

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I need to pick up a couple of scrap heads for mock up then I can get on with some fabrication on the headers.

 

Picked up a junk cylinder head tonight to use for mock up and ordered some stainless tube to modify the headers. Quite a bit of modification to do, including some braces to support the weight of the turbos and prevent the headers cracking.... all will become clear!