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GT45 Turbo For Dummies

General engine tech -- Drag Racing to Circle Track

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The Californian
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GT45 Turbo For Dummies

Post by The Californian »

Okay.

Say we dive in to the world of turbos by getting a Made in China $158 GT 45 turbo.

Have seen a lot of housings (turbine?) for the GT35.

IF the GT45 ones come with different housings (A/R .83 .6 1.0) what housing should we get?

https://www.ebay.com/sch/i.html?_from=R ... o&_sacat=0

Thank you.
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Orr89rocz
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Re: GT45 Turbo For Dummies

Post by Orr89rocz »

Kinda need to know what its goin onand how you are going to use it and where it’s mounted
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Re: GT45 Turbo For Dummies

Post by 67satellite »

I run two of them on a 470 B.B.M. and bought them "back in the day" when they were $249. I didn't know they came with different exhaust A/R's. I would caution you to disassemble, clean & de-chip them before use. Found numerous burrs hanging around in mine. Other than that they work well for what they are. Car craft did some articles on them with good results, and found their predictable limitations running a single on a larger engine. A quick Google search should find them.
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Re: GT45 Turbo For Dummies

Post by The Californian »

'what its goin on'

Okay.We will play ball and do it that way.

Think we can kiss the GT45 goodbye though.

Wahh! It is ONLY $20 more than the rest of the GT's on Ebay!

And it is nice and big! Equal size turbine and compressor.What a swell turbo!

An 80 hp 145 cubic inch Corvair engine.NOT beefed up for turbocharging.NOT a factory turbo engine.

If we burn it down that will be okay though.We LIKE pistons with holes burned through the tops!

I take it this will push us down to a GT35 or GT25?
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67satellite
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Re: GT45 Turbo For Dummies

Post by 67satellite »

Not an expert by any means, but I will suggest reading "Maximun Boost" by Corky Bell. That and the internet is all the "training" I had. The G.T. 45 is way too big for that engine. Get lots more info before spending your hard earned $$$.Cheaper to only do it once.
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Re: GT45 Turbo For Dummies

Post by The Californian »

'G.T. 45 is way too big for that engine'

That works for us!

So.What about the other Ebay turbos?

T3/T4 Hybrid

GT 15 Pretty sure there are those.Think they say they are for motorcycles and small engines.

GT 25

GT 35 Think a lot of people get those.Sure were a ton of different turbine housings there.

Don't like a mismatched turbine and compressor.Just looks wrong.

GT 3028 I think

So.Which one?
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Re: GT45 Turbo For Dummies

Post by The Californian »

Here is a youtube about twin GT 45's on a drag car.

https://www.youtube.com/watch?v=Jj4sJCNevXw

Compares turbos.Think he ends up with GT 45 with 'small area housings'.

Kind of like the 'put it on and see what happens' approach.

Guess it helps to get in the ballpark though.
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67satellite
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Re: GT45 Turbo For Dummies

Post by 67satellite »

Decide what engine combo you are going to run, educate yourself and determine what you need to meet your performance goals. Absent that, consult with a professional, not just an Ebay seller, have them choose a turbo that will meet your need, and buy it from them. The latter would probably be your best path to success.
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Re: GT45 Turbo For Dummies

Post by ptuomov »

67satellite wrote: Mon Jul 27, 2020 9:35 pm Decide what engine combo you are going to run, educate yourself and determine what you need to meet your performance goals. Absent that, consult with a professional, not just an Ebay seller, have them choose a turbo that will meet your need, and buy it from them. The latter would probably be your best path to success.
I think this calculator seems to be pretty well done for turbo selection, thoughts?

http://www.turbos.bwauto.com/aftermarke ... rsin=92044&

Sorry about the long link.
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The Californian
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Re: GT45 Turbo For Dummies

Post by The Californian »

YES.We will press on with the pressure maps and the formulas.

Made the deal for the third edition 1984 of Hugh MacInnes Turbochargers.

That guy was on engineering team that developed first small turbos in early 50's at TRW.

Back to the For Dummies approach.

Can the internal wastegate Ebay be converted to external wastegate? Can you just remove and block off internal wastegate?

Taking a shine to a little GT 25 one.It has internal wastegate though.

Probably get a GT 35 or GT 45 though.

Do have a big block we could stick it on.

CANNOT torch that engine though.So.That sort of takes some of the fun out of it.

Might just pick up a not so rare V8 something to experiment with.
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Re: GT45 Turbo For Dummies

Post by Jarmo »

I did built a mild 350 tpi engine with garrett T51 turbo that has pretty much same dimensions that those chinese GT45 turbos. With 1.15 exhaust A/R it did spool to 8 psi at under 3000 rpm and was very well matched to engine. Did make 600 hp at the crank under 5000 rpm (about 15 psi) and is a very nice and responsive street engine on a c4 vette.
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Re: GT45 Turbo For Dummies

Post by The Californian »

Hi Jarmo

Thank you for the real world example.

Single GT 45 on a small block Chevy.Got it.

You said it makes boost.That is a good thing.

Looks like with the stock Corvair engine we will have to go pretty small.

Rubs me the wrong way to get one of those T3/T4 Hybrids for $100.

Would like to get one a little more up the ladder and part of the GT family.

We'll see.
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Re: GT45 Turbo For Dummies

Post by Jarmo »

Perhaps you can find a good used mitsubishi evo 4 or newer turbo, 280 hp stock and room to grow. These have divided turbine housing that would be nice on flat six as you could keep both banks exhausts separated and that would help with back pressure. Could be a bit big still for a stock motor but these are good quality turbos compared to china offerings.
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Re: GT45 Turbo For Dummies

Post by Orr89rocz »

Any factory 1.8-2.4 liter 4 cyl turbo will do i suppose

Think mitsubishi td04 type turbos. K04 turbo off a cobalt ss is on the bigger size.

Figure the factory turbo cars are 200-300 hp easily.

40’s mm on the compressor inducer, 40’s on the exducer on the turbine.

Ebay has a ton on those small turbos for cheap but who knows how long they last. Biggest would be a Small t3 small housing as possible would help since your motor doesnt have alot of na power to turn thewheel.

The t25/t28 stuff is likely better for you. 36/44 comp and simliar turbine. Should spool faster and double your power easily
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Re: GT45 Turbo For Dummies

Post by The Californian »

Thank you Jarmo

'good used mitsubishi evo 4 or newer turbo'

That would be a good tip for somebody that has done their time with the imports.We have to keep it simple.See turbo get turbo.

'divided turbine housing that would be nice on flat six as you could keep both banks exhausts separated and that would help with back pressure'

Just ran across that in our first 1971 Hugh MacInnes How To... book.

Thank you Orr89rocz

'Any factory 1.8-2.4 liter 4 cyl turbo will do'

That and what you go on to say sounds like you know the cars and know turbos.

't25/t28 stuff is likely better for you'

Cool.Saw some youtubes and the guys seem okay with Made In China turbos.Also seemed like they were fairly sharp.

What would happen with a GT35 on our little Corvair engine?

The GT35 seems like the Holley 750 double pump of turbos.Real popular.

Would it run at all?

It would be 'pull through' with a 350-500 cfm carb.Straight out exhaust from the turbo and a driver controlled wastegate.

Thanks.
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