View Full Version : 455 Twin turbo STREET motor



stoneshrink
11-04-2011, 08:10 AM
Okay - 1st Thank you Paul - you've been an amazing help, even though this build is far more complex because of your input (it's really a good thing).

I'm build a 455 for my Skylark (I'll do a picture post later). The car itself is a long story, but the end is I'm going to build a 455 for it that will be streetable and not necessary for competition... just a dang cool motor that runs hard.

The specs
1976 Block
.030 over bore
forged, speed pro pistons
full girdle
Edelbrock heads
fuel injection
twin GT 2870 turbos

- in short, something simple, easy and reliable
I'm still not convinced on what cam to use.... probably will be hydraulic roller, but could be solid roller/ custom grind (imagine that, no off-the-shelf twin turbo 455 cams available)

tyoneal
11-07-2011, 11:24 AM
Be careful choosing a cam, because that will dictate the total personality of the engine. If this is a fun street motor use a Hydraulic Cam only! (KISS, Keep it simple .....)

Be sure the LSA has very little over lap 112* or higher otherwise you will bleed off your boost.

Make a call to 3 or 4 of the Big Cam Manufacturers and see what they offer. Be sure and have all the specs of your engine handy when you speak with them, and you don't need to go over board on the cam. A TT 455 when make tons of power so you don't need to go Crazy. Buy something Modest, If it doesn't make enough power you will want to re-asses your goals.

Be sure and stick to a street friendly engine, you will have a lot more fun and a lot less headache.

Google Turbo Buicks. There are a ton of sites that you can glean some information from.

If you can afford a intercooler, and can do the pluming correctly, do it. everything on the engine will work more efficiently, and you can run more boost without detonation. For the street try and stay away from alcohol injection. More Complicated=More Headache=More Expense.

Good luck,

Ty O'Neal

stoneshrink
11-07-2011, 10:51 PM
thanks for the input - problem with googling "Turbo Buick" is all you get are black cars.... not that there's anything wrong with that, however, for some reason (which I'm sure I'll find out) people don't turbo 455s... ah well, someone's got to be the hero (or the goat)

Cam specs

218/218 .525 lift, 114 LSA hydraulic roller. Should idle just like grandma's car.

tyoneal
11-08-2011, 08:53 PM
thanks for the input - problem with googling "Turbo Buick" is all you get are black cars.... not that there's anything wrong with that, however, for some reason (which I'm sure I'll find out) people don't turbo 455s... ah well, someone's got to be the hero (or the goat)

Cam specs

218/218 .525 lift, 114 LSA hydraulic roller. Should idle just like grandma's car.
======================================
What is your Compression Ratio?

The reason I mentioned the Turbo Buick is that the "Black Car" People are some of the most knowledgeable people with regards to Buick's and Turbo Chargers, Plus they will know all the best places to buy things for Turbo Charged Engines.

I know they can at least point you in the right direction. I would imagine that the main reason you don't see more of them is that the 455 can make a ton of power pretty easily without Turbo Chargers.

Make sure your block and heads are up to the task. 2 Bolt Main vs. 4 Bolt Mains, Forged bottom end, etc.

Can you describe what type and quality your parts are?

Ty

stoneshrink
11-08-2011, 09:29 PM
When I get done with this car, I'll have to post a book with acknowledgments in the back to all the people who have provided excellent input in this motor, the Skylark's suspension, and on this one - http://www.bangshift.com/forum/showthread.php/29229-CTS-Spider - which is my other "current" project. Before that my resume includes several blown Chevs, and about every combination you can have with 231s - including that terrible draw-through design turbo (fun when it ran). Cadillac motors in my Studebaker truck....

I appreciate the kind words about the guys (and gals) at TurboBuick.com. It is true there is a wealth of knowledge there.

I agree that the 455 is a pretty stout motor all by itself, however, when my dad was racing in the late 50s and early 60s, they used some parts that were amazingly weak - yet ran some pretty quick times - the trick they used was easing into the power.... the turbos on this 455 follows that same principle. It'd be breathtakingly easy to break this motor into small bits by abusing it so I won't. And still be very quick for a DD Buick. In my experience, there's no such thing as easy power...

Parts... to the above, of course everything is ARP studs. Intake and exhaust are things I enjoy building myself (I'm kind of sick in the head, but it keeps me happy).

CR will be 9.66:1
no 4 bolt main - wouldn't really help because of the weak web design of the 455 block, but there's a full girdle tying the mains to the side rails. No need for a forged crank, I'm going to live dangerously with shot peened, arp bolted rods. If anything breaks, it'll probably be the rods.



So enough about me - you have a current project or two?

bobc455
12-08-2011, 06:58 AM
A couple of thoughts here.

First of all, since this will be a true street motor and the turbocharging is done mostly for the "coolness", you'll probably only want to run 6# of boost - 8# at most. Plus you won't want to exceed about 5500 RPM. That will eliminate you from needing a girdle and an intercooler, etc.

The nice thing about the black cars is that they are exactly 1/2 of what you are doing - they run a 231CID motor with one turbo. 231*2=462, so with two turbos are doing about double what they do. You have essentially two of their engines.

However, the black cars tend to run a helluva lot more boost. I know guys that run the black cars at 25 to 27 PSI, and run alcohol and intercoolers. Your stock block would be blown to smithereens WAY before you ever hit 27PSI!!! So the knowledge that the black guys have won't really apply to you. Even stock, the GNs ran 12 PSI, so in theory the stock GN turbo is already much more than you need.

I don't know if this has been mentioned previously, but you'll need a lot more oil volume (not pressure) to handle your turbos. You might want to consider a new front cover from TA performance in your build.

For camshaft, i run a motor that relies on a lot of nitrous (which in most ways is similar to a boosted motor). My cam has 116 degrees of lobe separation. TA did a custom design for me. They will do a custom design for anyone, at no extra charge - the only downside is that you have to wait longer while the cam is ground. But to me, that time is totally worth it.

I run about 9.6 compression in my car, but I think that's too high. If I was building the motor again, I would run around 9.0 or maybe even slightly less. 9.6 is fine for a normally aspirated street car, but once you add nitrous or turbos (especially non-intercooled ones) I would rather see you drop the CR a bit. My pistons are custom-made by JE (through TA performance who created the specifications and worked with JE), however I think the forged Speed-Pros are designed as a nominal 10:1 piston. Also, they are designed for NA motors, and for a boosted engine you might want to consider a piston designed to work with boost (slightly larger top land, etc.).

-Bob Cunningham

stoneshrink
12-08-2011, 09:07 AM
I always cringe when someone says I'm building something for the "coolness" factor. It's not, turbos allow you to get incredible hp while being able to drive it on the street. This motor will be 700 hp, I challenge you to build a 700 hp motor NA motor that you can drive on the street that operates vacuum brakes, idles smoothly, and doesn't load up at lights.

I'm intercooling the turbos, and it will be port-efi. the only coolness is it will be the Buick equivalent of the Kurt Urbain (former) Nova. Look like grandma's car.... probably be grey when it's done.

It also has a girdle - just because I'm building it where it could survive, I also recognize that I could upgrade turbos and injectors and be in the hero world.... all without hood scoops and idling like a kitten.

bobc455
12-08-2011, 11:09 AM
How much boost pressure do you plan to run?

-BC

p.s. I LOVE the "grandma's car" thing. I bought my car from my grandmother - so it is a true grandma's car. Sleepers rock!

stoneshrink
12-08-2011, 05:17 PM
6-8# all in before 5200 rpm. The goal of the turbos is to cure the lazy hp curve in a manner that doesn't break parts with sudden pressure (such as happens with nitrous)

I actually have (and use) the afghan that was in my 1st skylark....

bobc455
12-09-2011, 04:48 AM
Then do you really think you need an intercooler?

If it were me, on 8# I would not intercool. Intercooling adds a lot of extra underhood hardware, and I like to work a lot under the hood. Right now, I can completely pull my motor by myself, working at a casual pace, in about two hours. I feel like if you add an intercooler to the mix, things will be very complicated under the hood. It's not a bad thing to intercool from a performance perspective, but it's not like you are running 22# and your air temps are astronomical.

I've looked into supercharging quite a bit, and I was going to go down that road for a while. (In fact I have a procharger sitting in the garage that I haven't installed, but that's a different story for another day.) And even up to 10# of boost, I would probably not intercool, but I realize that would be running on the edge.

And don't go nitrous bashing - as long as you use good hardware, and use it intelligently, it is an amazing power adder. But I won't preach...

-BC

stoneshrink
12-09-2011, 08:22 AM
Do I need an intercooler, yes. Intercooling does several things, but these are the most important to me - it reduces engine temps and keeps the motor operating in its green zone; provides the foundation for the next motor; and it reduces knock. To remind, 9.66:1 compression.

I had to chuckle at the reason why you're against it, because it makes it easier to pull the motor. For the stuff I do, if the motor is coming out in less than 20k miles, I did something wrong in the build - thus, I abhor fixing what I could have done right the first time, so most of my motors don't come out of their car. There are exceptions (aka lessons) where that isn't true - but, for the most part, it's what I do. But certainly, I have friends that if there's a small drip; the motor comes out - I joke with them that need to install engine removal zippers...

I'm not against nitrous, it's just not what I use because it doesn't fit with what I do. Most of my cars are either brutal daily drivers, or autocross. I don't drag race, almost never show, so bottle filling just doesn't work.

Supercharging, I've done it on 3 different motors and I'll never do it again... I've found them to be too temperamental. That said, the procharger you have is about the only one that I'd even consider because it can be intercooled fairly easily..... funny, and as I typed that I reminded myself that I might be putting a magna charger on my 06 GTO....

bobc455
12-09-2011, 01:03 PM
It isn't just pulling the motor, it's all around accessibility. And the cost of the intercooler with its additional plumbing. But I certainly won't stop you from doing it! The benefits are unquestionable. I'm just talking about how I would do it.

Sounds like an awesome build, I look forward to the results!

-BC

stoneshrink
12-09-2011, 01:11 PM
I always chuckle when people talk about working space... here's the Buick

http://i230.photobucket.com/albums/ee308/stoneshrink/1970%20Buick/P2220005.jpg

And here's my other major, current project (3.6l VVT Cad motor with turbos)

http://i230.photobucket.com/albums/ee308/stoneshrink/Spider/PB210011.jpg

http://i230.photobucket.com/albums/ee308/stoneshrink/Spider/PB230002-1.jpg

stoneshrink
12-09-2011, 07:26 PM
that above thing I said sounded harsh.... not meant to be harsh - just a PG glimpse into my first thought :)

pmuller9
12-09-2011, 10:54 PM
;
Supercharging, I've done it on 3 different motors and I'll never do it again... I've found them to be too temperamental.

What type of superchargers did you use?
Roots or twin screw?

Paul

carmantx
12-10-2011, 07:38 AM
thought I would tag along here.

We too plan to build a twin turbo BBB for the 70 Skylark for street. Current target is an 8.90 pass. Car weighs 2750 with a BBB. Chassis work will be first, and trying to decide to backhalf the car, or not. Engine build is later down the road. Current build is the V6 turbo for the GN. Almost done with it.

stoneshrink
12-10-2011, 07:43 AM
What type of superchargers did you use?
Roots or twin screw?

Paul

roots blowers - 6-71, and a B&M on two different motors

but, uh, aren't twin screw and roots blowers the same thing? did you mean centrifugal or roots?

stoneshrink
12-10-2011, 07:47 AM
thought I would tag along here.

We too plan to build a twin turbo BBB for the 70 Skylark for street. Current target is an 8.90 pass. Car weighs 2750 with a BBB. Chassis work will be first, and trying to decide to backhalf the car, or not. Engine build is later down the road. Current build is the V6 turbo for the GN. Almost done with it.

2750? wow, that's taking the Twinkies out of the Buick....

Dr. Frankenbuick
12-10-2011, 11:28 AM
but, uh, aren't twin screw and roots blowers the same thing? did you mean centrifugal or roots?


Here you go: http://kennebell.net/KBWebsite/Common/pdfs/twinscrew-vs-roots-fromcatalog.pdf. Love my twin screw!

pmuller9
12-10-2011, 11:33 AM
roots blowers - 6-71, and a B&M on two different motors

but, uh, aren't twin screw and roots blowers the same thing? did you mean centrifugal or roots?

There are 2 types of positive displacement superchargers. One is the roots type and the other is the twin screw.
There is also a design which is a cross between the two used by Eaton/Magnuson.

The roots supercharger is not an air compressor and produces manifold pressure simply by blowing more air into the engine than the engine can pump. Hence the word "Blower" used for description. The air is pushed around the outside of the rotors in the case from the inlet to the outlet side and most of it is prevented from returning where the rotors mesh. As the air pressure is increased on the outlet side so is the air temperature. Because there is clearance between the rotors some of the heated air gets returned to the inlet side where the rotors mesh giving the roots blower poor thermal efficiency.


http://dl.dropbox.com/u/9726298/Roots.jpg

The twin screw supercharger is a true air compressor. The screw and auger configuration compresses the air down the length of the case until it is discharged out the bottom. Since the air is always moving away from the inlet, heated outlet air cannot return to the inlet giving the twin screw design a high thermal efficiency. http://www.lysholm.us/showroom.php (http://www.lysholm.us/showroom.php)

http://dl.dropbox.com/u/9726298/twinscrew.jpg

The Eaton supercharger has roots style rotors.The rotors are twisted so the air is moved down the length of the case like the twin screw giving it many of the advantages of the twin screw.

http://dl.dropbox.com/u/9726298/Eaton.jpg
There are 3 main suppliers for twin screw street superchargers.
http://www.lysholm.us/ (http://www.lysholm.us/)
http://www.kennebell.net/KBWebsite/H...s/Homepage.htm (http://www.kennebell.net/KBWebsite/Home_pg/layouts/Homepage.htm)
http://www.whipplesuperchargers.com/ (http://www.whipplesuperchargers.com/)

And the Eaton supercharger

http://www.magnusonproducts.com/ (http://www.magnusonproducts.com/)
http://www.eaton.com/EatonCom/Produc...Superchargers/ (http://www.eaton.com/EatonCom/ProductsServices/PerformanceProducts/Products/Superchargers/)

All of the above companies supply their superchargers with a bypass valve.
When boost is not needed the valve is open and the supercharger is bypassed. When you are just cruising it takes less than 1 hp to drive the supercharger.
Step on the gas pedal, the valve closes and instant boost.

The Axial models are for EFI and the Radial models are for carburetors.

Because the twin screw is much more efficient than the roots, intercooling is not so much of an issue
and at lower boost is usually not needed.

It's expensive, but Whipple makes intercoolers that sit in the intake mainifold

Kenne Bell liquid cools their superchargers.

Unlike turbochargers, boost begins to build from an idle and you can have max boost by 2000 rpm
There is no boost lag which is important when running a manual transmission.
Having to wait to regain turbocharger boost after a shift is frustrating.

Paul

carmantx
12-10-2011, 03:52 PM
2750 was race weight.
Wasn't easy. fiberglass hood, fenders, bumpers, and lots of extra metal cut out.

It will be a fun street car.

http://i359.photobucket.com/albums/oo37/1972gsx/1970%20car/GSXGN_105.jpg

pmuller9
12-10-2011, 04:00 PM
Nice Job

Weight reduction is not easy or cheap but it sure helps reduce the amount of HP needed to go fast
not to mention the reduction in parts breakage.

It takes us just under 1000 flywheel hp to go 8.90s in a 3600 lb car

Will you be using blow through carb or EFI on the turbo Big block?

Paul

carmantx
12-10-2011, 04:04 PM
Thinking blow through at this point.

Car has everything pulled out of it now to start over. 464 is in our red 72 GSX now. With a little ole 100 shot of nitrous.

pmuller9
12-10-2011, 04:07 PM
Thinking blow through at this point.

Car has everything pulled out of it now to start over. 464 is in our red 72 GSX now. With a little ole 100 shot of nitrous.

Will you be using the 464 for the turbo engine?
If not may I make some suggestions?

carmantx
12-10-2011, 04:35 PM
This 464 is staying in the red car. 462 in my convertible.
Not positive on the set up for the turbo BBB yet. My son is gathering the specs for it.

pmuller9
12-10-2011, 05:02 PM
This 464 is staying in the red car. 462 in my convertible.
Not positive on the set up for the turbo BBB yet. My son is gathering the specs for it.

Here's my recommendations that you can run by your son.

430 cid is actually a better match for the size turbo's you are going to be using.
The 430 blocks usually have a much thicker cylinder wall than the 455s

A great combination would be a girdled 430 block, regrind the crank rod journals
for off the shelf BBC rods and use custom 9:1 pistons.

The TA Stage 2 heads give a lot more room for the turbo exhaust headers
and the better flowing exhaust ports will give a lot better results with a single profile turbo grind

TA is doing a 218/218 .325 lobe lift on a 114 lobe center roller cam for Stoneshrink's turbo engine.

Paul

stoneshrink
12-10-2011, 05:37 PM
d'oh... yeah, that too - about 10 min after I typed my question, I thought "oh yeah, screw, like a magnacharger - the one I'm planning on putting on my GTO"...

past tense on the cam, it's been ground, now sitting on my shelf :thumbsup: