chevy 250 inline turbo.

General engine tech -- Drag Racing to Circle Track

Moderator: Team

chevyfreak
Pro
Pro
Posts: 493
Joined: Sat Oct 04, 2014 4:23 am
Location: south africa johannesburg

chevy 250 inline turbo.

Post by chevyfreak »

Hi everyone.
In need of some assistance please. My buddy talked me inti doing a turbo 250 inline 6. And myself have been plondering about it but still buzy on my other builds so its at the back of the line,or was.
he has the following turbo and just wants to build a bolt on low boost setup. Running 7 to 8lbs boost. Afaik blow thru carb.
TurboT3/T4 (internal wastegate)
T3 AR.48 Turbine Housing T3 stage 3 Turbine Wheel T04E AR.50 Compressor Housing Compressor Wheel(53mm-76mm).
now the questions. Wil this turbo work ? Im not that much clued up with turbos but im also interested as i wanted to do one myself later on.
any help/info much appreciated. Thanks
chevyfreak.
Bowtie for life
wyrmrider
Guru
Guru
Posts: 6941
Joined: Thu Jan 10, 2013 10:52 pm
Location:

Re: chevy 250 inline turbo.

Post by wyrmrider »

Hi freak
The late great Kay Sissell had a turbo 250 in his van way back when
Here's what I'd do
get a set of forged 307 pistons (flat top) even TRW and mill a "d" cup (like the TRW "Turbo piston" to get compression where you want it and get a 0.0 deck
with a 6 you do not have to reballance unless you are fastidious
new rod bolts

In mine I run a custom Jones cam (replace an I.O. mercurser 4 with the 6- heavy Iron marine manifold and marine 2bbl carb with flame arrestor)
ran the motor on Sissell's dyno using one of his non lump ported heads
chickend out at 6500 rpm
Ks Fats
Pro
Pro
Posts: 375
Joined: Wed Feb 12, 2014 12:39 pm
Location:

Re: chevy 250 inline turbo.

Post by Ks Fats »

Freak,
In addition to the info above; look for a 292 exhaust manifold (cast iron); the outlet is 2&1/4 and will help with the turbo hook-up. Has a three bolt flange and the larger outlet; might have to do some searching in South Africa. That engine was used in a lot of agricultural, industrial and truck applications. I've only been able to find the 307 piston with the chamfer around the head, true flattops are getting harder to find. In your case it would be beneficial as the chamfer will reduce the comp. ratio somewhat. Once you sort it out add a 50 shot of nitrous; just enough to help spool the turbo.
Xnke
Pro
Pro
Posts: 343
Joined: Mon Aug 20, 2012 7:39 pm
Location:

Re: chevy 250 inline turbo.

Post by Xnke »

That turbine housing, being a T3 0.48 A/R, is going to be too small. You'll likely be overrevving the turbo pretty low in the engine's RPM band, but that is something easily fixable later-turbine housings aren't hard to get. Look for a 0.63, or *maybe* a 0.82 depending on where you want the power band. I'd try the 0.63 first.
chevyfreak
Pro
Pro
Posts: 493
Joined: Sat Oct 04, 2014 4:23 am
Location: south africa johannesburg

Re: chevy 250 inline turbo.

Post by chevyfreak »

Hi.
Over here only the c30 had the 292 motor and from the ones i have seen and the ones we got they have the normal 2" outlets. Gm didnt give as much over here so they used what they had. Pistons in motor is d dish and running 8:1 comp ratio at moment. He only wants to do a bolt on setup so not to many changes is planned.
Xnke wrote:That turbine housing, being a T3 0.48 A/R, is going to be too small. You'll likely be overrevving the turbo pretty low in the engine's RPM band, but that is something easily fixable later-turbine housings aren't hard to get. Look for a 0.63, or *maybe* a 0.82 depending on where you want the power band. I'd try the 0.63 first.
he has the turbo and i know what shop it came from and they do have a variety of housings.
Thanks to all.
cheers
chevyfreak.
Bowtie for life
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: chevy 250 inline turbo.

Post by PackardV8 »

Would anyone else recommend starting with a 292"?
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
chevyfreak
Pro
Pro
Posts: 493
Joined: Sat Oct 04, 2014 4:23 am
Location: south africa johannesburg

Re: chevy 250 inline turbo.

Post by chevyfreak »

PackardV8 wrote:Would anyone else recommend starting with a 292"?
I asked him the same thing. But he hasnt got a spare 292 motor to utilize and it wont fit in body as well. Its in a holden hq ute which for us here its relabeled as a chevy elcamino. The 292 is to tall to fit under hood. I have checked before as i wanted to fit one in mine.
They ( him and his 2 brothers) almost have a variety of them (cars ,wagons and pick ups( various year models)) with inline and v8 motors chev and holden drivetrains and even one with a 4.3 v6 and he wants to do a turbo setup. And would like to do a 250 motor.
im also interested in doing same thing so we decided to give it a shot. And he has a turbo already just wasnt sure if it would be suitable.
Thanks for all input and suggestions.
im gonna find out tomorrow on another turbine housing. Will be keeping all updated.
Cheers
Chevyfreak.
Bowtie for life
PackardV8
Guru
Guru
Posts: 7619
Joined: Sun Jul 30, 2006 2:03 pm
Location: Spokane, WA

Re: chevy 250 inline turbo.

Post by PackardV8 »

They ( him and his 2 brothers) almost have a variety of them (cars ,wagons and pick ups( various year models)) with inline and v8 motors chev and holden drivetrains and even one with a 4.3 v6 and he wants to do a turbo setup.
Most of what our customers do doesn't make any economic sense. When they've got V8 and 4.3 V6 rigs and spend the money to do a 250" I6 turbo, that's a "just because I want to." Good on 'em!
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
wyrmrider
Guru
Guru
Posts: 6941
Joined: Thu Jan 10, 2013 10:52 pm
Location:

Re: chevy 250 inline turbo.

Post by wyrmrider »

how do you get a tight quench with the bevel or d dish pistons
if you run down he hole be prepared to spend time on your advance curve and fuel
292 would take custom pistons- no (relatively) easy fix like with 250
you could calculate with 292 head and drop the compression
chevyfreak
Pro
Pro
Posts: 493
Joined: Sat Oct 04, 2014 4:23 am
Location: south africa johannesburg

Re: chevy 250 inline turbo.

Post by chevyfreak »

wyrmrider wrote:how do you get a tight quench with the bevel or d dish pistons
if you run down he hole be prepared to spend time on your advance curve and fuel
292 would take custom pistons- no (relatively) easy fix like with 250
you could calculate with 292 head and drop the compression
When he build the motor i wasnt present so i dont know what he checked or calculated. All he told me is its a stock motor and cr is at 8:1.
Motor is a low miler and is mostly used for shows and a bit of driving now and then. The way i know him he wont go past 5000rpm and wont be going on a drag strip but he will smoke a tyre once in a blue moon and will have a bit of race here and there. He likes the drive more than the speed.

PackardV8 wrote:
They ( him and his 2 brothers) almost have a variety of them (cars ,wagons and pick ups( various year models)) with inline and v8 motors chev and holden drivetrains and even one with a 4.3 v6 and he wants to do a turbo setup.
Most of what our customers do doesn't make any economic sense. When they've got V8 and 4.3 V6 rigs and spend the money to do a 250" I6 turbo, that's a "just because I want to." Good on 'em!

Believe me they have got and do build weurd things just because they can. And i know if you tell them it will not work they will at lease try and see and mostly they do get something weird and wacky . They have 37 show cars between them all gm (mostly,think 3 isnot general motors) and mostly still original. And then there is some creations.
Im going past him after work and will be discussing and see what is his ideas and see from there.
Thanks
Chevyfreak.
Bowtie for life
chevyfreak
Pro
Pro
Posts: 493
Joined: Sat Oct 04, 2014 4:23 am
Location: south africa johannesburg

Re: chevy 250 inline turbo.

Post by chevyfreak »

Just an update.
Will be changing turbine housing to a .63 as recommended (thanks xnke.)
and he has a hei dizzy as well. Looked at space to fit turbo so thats all sorted and having a pipe bent from manifold and flanges cut to eliminate the donut gasket on manifold side and a brace will be added to hold weight of turbo.
Had a long discussion and he wil be using weber intake and a 38dgv weber (still got to have a look on them and see for blowthru setup,
Only other thing im worried about is the vacuum side of things brake booster and especially vacuum modulator on trans. (Th350).
Thanks.
Chevyfreak.
Bowtie for life
gofaster
HotPass
HotPass
Posts: 536
Joined: Fri Apr 15, 2005 8:21 am
Location: Indiana
Contact:

Re: chevy 250 inline turbo.

Post by gofaster »

292 would take custom pistons- no (relatively) easy fix like with 250
you could calculate with 292 head and drop the compression
Back in the late 70's or early 80's I built a 292 motor for an oval track car. Bill Miller built a set of rods for me using a Hemi blank and moving the wristpin hole. Can't remember what pistons I used, but they were an off the shelf forging for a V-8. The modified Hemi rod got the pistons to zero deck. I can't remember much else about that one. Maybe doing something like that will help you.
Jim McMahon
Heads1st
http://www.heads1st.com/
turbobaldur
Pro
Pro
Posts: 238
Joined: Wed Jan 22, 2014 9:51 am
Location: Iceland
Contact:

Re: chevy 250 inline turbo.

Post by turbobaldur »

Beware of one thing when changing turbine housings. A housing must match the turbine wheel. If the housing doesn't snugly fit the wheel you will get large amounts of turbo lag and limited amounts of boost pressure as exhaust will be short circuiting past the wheel.
chevyfreak
Pro
Pro
Posts: 493
Joined: Sat Oct 04, 2014 4:23 am
Location: south africa johannesburg

Re: chevy 250 inline turbo.

Post by chevyfreak »

turbobaldur wrote:Beware of one thing when changing turbine housings. A housing must match the turbine wheel. If the housing doesn't snugly fit the wheel you will get large amounts of turbo lag and limited amounts of boost pressure as exhaust will be short circuiting past the wheel.
I went to the dealer that the turbo came from and he has the right housing to match the wheel . And price wise not that expensive.

Chevyfreak.
Bowtie for life
DaveMcLain
Guru
Guru
Posts: 2858
Joined: Thu Jan 06, 2011 8:57 am
Location:

Re: chevy 250 inline turbo.

Post by DaveMcLain »

Didn't GM actually sell a turbo version of the new style inline six somewhere in the world? A 250 with a turbo maybe?
Post Reply