Twin Turbo Question?

[Rivman73]

I'm in the middle of building a twin turbo 455 for a 73' Riv. It's going to be a 462, 8.1:1 comp., Edelbrock heads, a TA TA 296-08H10 cam, And a SP1 modified for fuel injection.

I'm looking a 2, T70 P-Trim Turbos, Do you think this is a good choice?????


(Turbo specs= SUPER 70 60.5mm • A/R RATIO .70 • TURBINE HOUSING A/R .84 • COMPRESSOR HOUSING .70 • T3/T4 FLANGE)

[kia]

please post a lot of pic when it,s done ,I always think of twin turbo 455,what kind of horse power you have in mind?1000 HP or more :Dou: :Brow: :3gears:

[Rivman73]

I'm hoping to turn at least 700 on pump gas mabye more on race fuel. I working on an air to water intercooler so it should be possible.

[bobc455]

I know you are looking for a comment on the turbo size, and I cant give that. However, I know that with 2 turbos it will be easy to go right by 700HP!

I think you will not need more than about 10 PSI. Even that might be too much...

Your drivetrain will also need a whole lot of attention to handle that HP!

It sounds like a very exciting project!

-Bob Cunningham

[Stage0]

I'm in the middle of building a twin turbo 455 for a 73' Riv. It's going to be a 462, 8.1:1 comp., Edelbrock heads, a TA TA 296-08H10 cam, And a SP1 modified for fuel injection.

I'm looking a 2, T70 P-Trim Turbos, Do you think this is a good choice?????


(Turbo specs= SUPER 70 60.5mm • A/R RATIO .70 • TURBINE HOUSING A/R .84 • COMPRESSOR HOUSING .70 • T3/T4 FLANGE)


Those turbo's will be plenty big enough to make 700RWHP. Stay away from seller's like ssautochrome.
It'll make that power on pump gas without the air/water cooler
That cam's not a great choice for a turbo motor.
Good luck and keep us posted :TU:

[AZ-69 Skylark]

Here's what I came up with for a 455 with 2 turbos at the Ray Hall site-it's a rough estimate.

http://www.turbofast.com.au/TFmatch.html




Maximum RPM
6000

Turbo Boost
8

I/C
YES

MAKE
Garrett

TYPE
GT25

HP Rating
400

TURBINE HSG A/R
0.8200000000000001

BHP-788.48

Air Flow Lb per Minute-72.57198336304606

[greensbuickfarm]

Why not go with a Holset? MUCH eaiser to plumb...two HX35s (Cummins Turbo Diesel) would get you over 700HP. HX40s well beyond that...plus, they are good for 50psi, if needed !

FWIW, my turbo guy swtiched from two Rajays on a 468BBC drag boat (950HP @24 psi) to two HX50s and made 1226HP.--at the same 24psi!

Oh-- and you can go old schooll holset--WH1Cs are similar to the HX35s and 40s, and can be found for ~$150...(I think I paid $250 for the pair I have)

Jason

[1badbuick]

You might want to think of a giant single setup as well there might not be as much plumbing involved. a t88 or a gt42r would be real nice.

[bobc455]

There would be easier oil plumbing for sure, but now you would have to come up with some funky-looking exhaust piping...

-Bob C.

[Rivman73]

I'm going to stick with 2. The only problem were having right now is fitting them and retaining the air conditioning.(which is a must) I am still looking for the best choice in turbos too. Thanks for all the advice.


Kevin

[buickdav]

Kevin,

Just another opinion here. Your comment about wanting to keep the A/C leads me to believe this is gonna be a more of a driver. Which is fine. But your looking for hp in the 700+ range. When you make that comment, I instantly see you needing every girdle out there, a great set of rod, heads studs, main studs, and every other full on race trick out there for a 455". I am not trying to scare you off of your plan cause' I think its a really cool one. BUT, there are a few red flags that popped up, to me at least, in your posts. Your hp goal, cam choice, (assumed)use of the vehicle, as a few. Your goal is indeed "do-able", I wouldn't use that cam personally, and I for sure wouldn't use 2 turbos if I planned on keeping the a/c on the car. It wont take long and you'll run out room under hood. I learned that the hard way. Keep everyone updated on your progress, if you like. I know there are a handful of BBB guys out there that are considering what your doing right now. Good luck.

[Rivman73]

Thank you guys for all the advice!! One of the reasons I'm doing this is I would like to have a nice car to take on power tour(for example), and the other reason is to make a point with somthing different. So I'm building a buick for 1, and it's a 73 Riv for 2, and on top of it we are trying to keep all the power acc. and probly add some.

As for AC I've decided to go to an aftermarket unit and I'm also going with a modern power steering pump with remote res.

I'm also looking at having a custon roller cam cut, or at least a custom flat tappet.

(I have a set of TA sportsman rod and both there girdles going into this motor, we are also considering a crank.)

And again Thank you and I will keep you all updated.

[DEL]

One thing is for sure, you're building a MONSTER!

I can speak from some experience having had a 70 P-trim turbo on my 86 T-Type. That car ran 10.40's @ 129 and was once dyno'd at just over 500 RWHP.

The key will be making it spool. You could likely get away with a smaller turbo and it should spool faster but the EFI boxes (Like the FAST system) can help you spool even with big turbos.

The only other comment would be to do whatever you can to remove any restrictions after the turbo. Chances are you don't need any mufflers at all. A lot of guys just run bullet mufflers. Anyway less restriction will help it spool as well.

Good luck to you, can't wait to see some pics once you get going on it.

[Rivman73]

So what do you guy's think of 2 Holset H2D's at 10 PSI??? Will it stay together???

[toyman]

:beer You have a dream of mine also, only you look to be closing in on it. 2 turbos is the ticket, and keep the AC also :beer . You need to check out STS (squires turbo systems). Put the turbos in the back.......yep.....remove mufflers, add turbos. Check out their website,....I am sold on the idea, no heat under the hood, no space requirments, just lots of intake tubing(airfilters in the back too!!!) Here's my plan.......STAGE1-build a strong bottom end w/girdle, 10 to 1 compression with carb for initial break in, ...STAGE2 - add fuel injection and switch to burning E85 ethonal fuel (high octane baby).....Stage3- add turbos in the rear with intercooler in front(super cool air temps!!!)..... all while adding hydroboost power brakes and moving ac system into rear deck like in a full sized conversion van with modern smaller ac compressor......the underhood will have uniformity and lots of space.....people will not believe it has turbos and AC.....also, battery in trunk make for more weight over the rear axle.....I am very serious about this, the project may begin this winter pending repair of my funding problems but is planned on taking a few years anyway........I believe turbos and E85 ethonal are the future...FOR MY 68 Special Deluxe Anyway :laugh:

[58buickspecial]

thinking of doing something similar with a caddy 500 into a 20's 30's anything. Hidden twin turbos, unless you look hard enough, you wont know what goin on. 7-800 hp out of mostly salvage yard parts. I'll be interested on your progress. :beer

[junglejim75]

I remember reading somewhere that when you mount the turbo's in back that the long tube to the intake actually funtions as its own intercooler, just a straight tube instead of a radiator style.... Jim

[87GN@Tahoe]

you could use a straight fluted or finned aluminum tube, would help a ton in cooling the air charge... cost for that type of tubing would be mighty pricy though and custom, most likely, in the sizes you'd need... problem might be lag though with LONG tubing... depending on turbo sizing and type (ball bearing etc.)I suppose

[CTX-SLPR]

Which is easier to blow up a large balloon or a small one? The combination of an intercooler and an "STS-style" rear mounted turbo system would be monsterous lag. The rear mounted system is really designed for engines that A)can't fit them around the engine anywhere or B)are basically stock compression and can only tollerate low booste. Its an add-on system, not a turbo conversion persay. It works well, particularly on bigger engines, but has far less potential, especially at the track, than a "properly" designed front mounted turbo system. You loose heat and have a large volume to pressurize in the exhauste path back to to the turbo then you have the same volume to pressurize on the way back to the intake. While you may loose a good amount of the intake charge heat out of the tubing on the way back, its still hot pressurized air coming back to the intake and an engine will be octane limited as to how much booste it will hold without detonation.
Spool time is heavily infulenced by exhauste volume pre-turbo, turbine and compressor wheel mass, bearing type, and turbine and compressor size. A fast spooling turbo of equal size and location will have a ceramic wheel on the turbine and an aluminum wheel on the compressor with ceramic ball bearings. This will get you a very very pricey but fast as possible spooling turbo for the location its in. Change the location and the closer to the exhauste ports you get the larger turbo you can run with the same spool time but its a bit logrythmic as after a certian distance you no longer see any real improvement in spool or sizing while the longer you get the worse it gets. Larger turbo's move more air and create less flow restriction on the exhauste but thier size makes them spool up slower, interia does not play in your favor. Ideally you want equal length headers running into the turbo with a length somewhere under about 2' ballpark with a turbo that hits its peak pressure ratio right at your peak horsepower, so when you start to run your engine out of steam the turbo is moving out of its peak efficiency aswell, this should give you the best ballance of spool and airflow capacity. If you really want to dig into this head over to the Turbo Buick boards at www.turbobuick.com www.turbobuicks.com and www.t6p.com .
Please do not take my post as gospel as there are many people out there with more experience with turbos than I do but from my experience and the physics of it this is my current understanding of turbos and system design.

[mike s]

You can run turbos in back of car but you need a electric oil pump for the turbos. Check out c-5 vet turbos, their rear mounted. The pipes to rear plus a small intercooler, make intercooler eff. like 60 plus percent.

[simon1243]

you also need an oil pump to return the oil back to the engine. i cant wait to see how your going to do this! i would love to put 2 turbos on my 73 riv!

[CTX-SLPR]

Your Riv probably has more than enough room to package them properly under the hood with a real intercooler. What kind of engine mods have/will you be doing in preperation for that?

[toyman]

Thanks CTX for the input, replies from turbo guys are much needed here. I am still gonna keep an eye on the STS rear ideas. Their website does a good job of explaining the physics, but obviously they are gonna cloud the negatives if there are any because they need to sell their product. I will definitely be asking a lot of questions more than ever.

[simon1243]

hows the twin turbo boattail coming along? any new news?

[67RivDog]

hows the twin turbo boattail coming along? any new news?

Curious myself.

This is such a cool endeavor. I'm living vicariously through you. :TU:

[GRIMM]

where would you put the turbos in the back so they would be out of the way?

i have an idea for you, run your AC through your intercooler to increase efficiency :laugh:

this makes a new idea in my head, maybe next time.

[462bbbcamaro]

Gm High Tech Performance magazine (or whatever it's called exactly) did a feature awhlie back on a rear mount turbo set-up for f-bodies with LT-1 and LS-1 motors. According to the article there was (surprisingly to me) almost no turbo lag and like Jim said the plumbing is the intercooler.
What about 2 GN turbos since a 462 is exactly twice a 231 and 350 hp out of a GN is easy? Twin turboing my motor that way has always been one of my fantasies :Brow: .
Good luck!!! :beer

[bmxmon]

So you guys are running efi on your 455's? Home fabricated or is there actually a stock 455 efi source?

[Gran Sport66]

Kevin, any update on this? Is it on it's way??

[freak6264]

The aftermount turbo is by a company called squires turbo systems. STS makes kits for most later model vehicles, single and dual in the 5K to 14K range. The benefits are numerous, including cooler underhood temps, less lag than a conventional system, faster spool (you're using a cooler(more dense) exhaust charge, and in the case of a single turbo system, a more powerful exhaust charge due to the fact you are using the entire engines exhaust) a much simpler install, (no manifold to fab), no intercooler to install, a cleaner engine bay, and much cooler running turbos- which in turn means more efficiency, and a longer life for your turbos. The downsides are minimal. Cost is a little higher than doing a conventional turbo on a late model vehicle that has a kit available, and you have a very distinct (euro sounding) exhaust note, oiling is an issue, but they have pumps available, and 1 pump will feed two turbos with super cool oil no problem. You don't need mufflers for this system, single or dual... I have a design in work, but I need to make a custom efi manifold first... the rest will be pretty simple and centered around a fast efi system. I've done camaros, hemis, and one Impala (we hybrided a kit)...Awesome stuff!!