Inliners International Forums General Discussion Blown and Injected 292 Turbo help needed

Just had a 292 rebuilt for my 68 C20 8’ stepside (spelled heavy!) with PS, A/C and PB. The 292 is basically stock, .040 over and decked .030, Holley 390 on a Offenhouser intake.
I and have not installed it yet (still running my 250) but am thinking of installing a turbo for low end performance and I just think it would be cool! This is a daily driver, frame up restore in black, 3 on the tree with a R10 30% overdrive, 4.55 rear gear and 16” wheels. Not a street or track racer.
Confused about all the options for a turbo. Have seen the GSP GT35 T4 referenced and the price seems right. This would be a low RPM engine 3500-4000 probable so would want the turbo to spool up quickly without the need for high RPM output (low A/R ?). I guess the boost would not exceed 8-10 PSI?? and would make the Holley a blowthrough.
Not sure if I can install a IC but I have a GM HEI ignition and would think something like the MSD 6-BTM Boost Timing Master would be an advantage and/or/both a methanol/mix spray.
Have seen the SPI exhaust manifold (500.00) but would be able to make my own J pipe mount with waste gate from the 292 stock manifold and save $$$. As want to keep the cost down (at least the initial cost) but could continue to add to later as $$$ is available.
And then there are the vacuum power brakes assist issue… where do I get the vacuum… when you let off does the manifold go to a vacuum?

Sorry for the long post but I was trying to explain all aspects of my project and my confusion. Thanks…

I can answer the vacuum part. Engine vacuum returns the second you take your foot off the gas. It IS possible to "run out of vacuum" at the booster, if you drive aggressively and try to brake while on the gas. I assume you do not drive like that in everyday traffic....

The brake booster vacuum hose should have a one-way valve, which traps vacuum (keeping it simple here) inside the booster, enough for a couple of heavy brake applications. Then the booster "runs out of vacuum" and you need more engine vacuum to recover.

On adding a turbo, you need to lower the compression ratio quite a bit, to be able to run boost. You lose a little "snap" and power because of the lower compression while NOT on boost, but you'll more than make up for it when you can boost more. If the engine was already built right for a non-turbo engine, I would imagine the CR to be a bit too high to run a turbo worth the hassle, you would have to keep the boost so low it doesn't do much. Then again, if you are only looking for 6psi and you are committed to keeping detonation at bay and run that boost timing control, you MAY be ok. I would still look at the combustion chambers and possible valve pockets on the pistons, and smooth out all sharp edges to prevent hot spots.
I would not blindly slap a turbo on that pretty engine without properly prepping it for one. Not saying it can't be done.

Thanks for the info as this is what I need to know. Thought the vacuum would return once you get off the gas... should not be a problem.
The original CR of this engine was 8.5:1 and with the .030 decking not sure what it is now could possibly close to 9:1 and may be a bit to high for a turbo?
Will have to give this more thought to see if I think the investment is worth the modest gain in power from running such a low boost.
Part of this idea was the novelty of something a little different in a pickup. Everybody always goes to the SBC 350 (AFSBC) and for a good reason so you don't see many I6 292's especially with a turbo... guess I just like to be a little different!
What is thought about the eBay GSP GT35 T4? I know there must be reasons for such a low price but was wondering how it might work as a budget daily driver.
Thanks again for the input, well said.

Running 9:1 will be fine, just dont run 87 octane & boost it high.
That GSP GT35 T4 will work fine for you. Specs out OK.

It should spool-up faily good for a daily driver. Running a .84 A/R or bigger will give you turbo lag & will cause it to get into boost later in the RPM range.

I would install an intercooler. The price for a kit is not much & no reason not to install one.
You are running higher compression, not too high though, & you want to keep your intake air temps down as not to detonate.

Running 8:1 compression is cause for a doggy engine & mileage will suffer also.
With your truck there will be plenty of room for an intercooler.

Good luck.

MBHD

I haved used vacuum tanks off of 70's big cars. They are not very big and can be hidden. Helps when you have a big cam in an NA engine or if your engine dies and you need to stop.

X2
Extra volume in the can allows 1 or 2 more stops, never know when you're going to need them!

I have been on vacation and have not had a chance to get back to this post... but thanks for the input.
Using the formulas and maps on turboforums.com it appears that the T04B “60” turbine A/R of.63 would be the best match (300 CID, 4000 RPM and 10PSI with a PR of 1.68:1 and 28 LB/MIN) as it stays in the higher efficiency loops. I understand a turbine A/R of .63 should give a quicker spool but I could possibly want something with a lower A/R (if it can be found)for even a quicker spool since I will possibly never see much over 4000RPM and need the lower ranges more. Again I’m not a racer but just want the little extra power the turbo could give plus just the fun of messing with this project.
This is where the confusion starts… I have found many sources on the internet and many price ranges. I have limited $$$ and would settle for a lesser priced unit but do not want to buy “junk” and have seen prices from around 200.00 up to 1600.00. I need to stay in the 300.00-500.00 range but have no idea where to start. I have included several links of ones I have looked at and if someone has a chance to give me some feedback on these it would be appreciated. I have seen some good reports on RXRacing turbos and they are modestly priced. Here again they may have 2 models with the same A/R etc and one will be 200.00 and the other 400.00… not sure why. The Holset HX-40 looks like a popular model that might suite me but information is sketchy. Also, for my purposes I would think the internal WG would be a better choice.
Thanks...

Fastwayracer 196.00

Garrett 5431 620.00


turbocharged.com Price???

Holset HX-40 280.00

CXRacing 260.00

CXRacing 440.00 (better choice?)

I like the specs on the Holset HX-40 out of all the ones you listed.
Mainly because the turbine wheel will allow for better exhaust breathing.

Look more for other turbos w/close to the Holset HX-40 specs.

MBHD

Thanks... This will help me narrow it down although I am having a hard time find the specs, map, turbine A/R etc. for the HX-40 but will keep looking.

You will be surprised at how fast a 292 will spool up. a 60-1 with a p trim wheel and a .84 housing will spool up plenty fast.
If you put a .63 exh housing. It will be in boost at almost any throttle push that puts a load on the engine. It will become annoying.

I agree with Tom my favorite turbo for 400 to 500 HP setup is a 60-1 "p" trim turbine with a .84 a/r ratio. I have had very good results with this, but do not go any smaller than a "p" turbine this may even too small for your setup.

Harry

I think the .63 A/R will be perfect.
A .84 A/R will be laggy & will boost later in the RPM range
2500 RPM & higher, (don't think you are looking for that?)
You want boost to come in @ 1500-2000 RPM & up?
A 'Q" trim turbine wheel.
All you need is a 57 MM compressor wheel max for the boost level you are looking for.

Most likely you will not find a turbo w/a "Q" trim turbine wheel & a 57 MM compressor wheel, custom turbo required.
Look for a turbine wheel about 62-64 MM or around 2.3 - 2.5 " exducer size (the smaller measurement)

A GT 35 turbo will be fine w/a .63 A/R.

Something like these.
http://www.ebay.com/itm/TURBONETICS-T3-6...e02b7e1&vxp=mtr

http://www.ebay.com/itm/GT35-T3-Turbo-Ch...c1a2732&vxp=mtr

http://www.ebay.com/itm/GT35-T3-Turbo-Ch...c1a2732&vxp=mtr

The compressors are bigger than needed, but you can still use them.

You need to keep the turbine housing A/R in the .63-.68 range to be able to boost in the low RPM range you are looking for.

I think if someone cannot control the boost w/a .63 housing , there must have other issues going on.

Guys run .63 A/R housings on there 4.3/262 CI engines Syclone/Typhoon Chevy V-6 engines w/no boost control issues so you can also.

When these guys run a .84 A/R housing, they run a loose converter & boost comes in full by approx 2800-3000 RPM & up.

I am thinking a good street mannered engine that will boost soon in the low RPM range & give you boost when you need it & not have turbo lag.
Is this what you are interested in?




Just my opinion.

MBHD

You'all (yes I live in the Southeast!) have really helped (educate) me in trying to figure this out but I still have several issues that are pending. Internal or external WG? Of course the internal makes the plumbing much easier, and the overall cost could be less, but there must be advantages to the external as most of the turbos are that way. I will go external if it provides more advantages and plumbing is really not that big an issue. Another area is the T3 or T4 divided housing. I would assume in my case the undivided is what I would want (2.5" fabricated "J" tube from the 292 factory exhaust manifold) with the 4 bolt exit on the turbine. Hate to keep bring up some many issues but trying to get as close to correct the first time as possible. I am thinking I will buy a lower priced unit (200-300) to start with as a learning tool and then move to a better unit once I better understand what fits.

MDHD Sorry I did not see your last post, which looks to be very helpful, before I posted as you have already addressed some of my issues and I will look into your suggestions. Thanks and will get back.

I prefer the T4 housings. More choices for sizes. Also prefer the external wg. That is because most T4 do not have provisions for internal.

MBHD, Got interrupted and didn't completely read your last post before. I would say you have exactly defined my interest (possibly better that I have) and this is the approach that I will take. Yes I want it to come in very early and peak around 4000. I have looked at your links and these are similar to ones I have looked and I will probably choose from these very soon. Still trying to put together all the parts I will need! I currently have the engine on break-in stand, to break-in cam and lifters, check for leaks, and accessory brackets (had to make or modify all for the 292) and will install the turbo at the same time. Working inside the engine compartment of my truck is very difficult due to its height.

I figured I'd need to chime in on this one. My setup is working good, but will probably upgrade my turbo at some point.

Can the turbo experts give me a grade this one?:
http://www.ebay.com/itm/CUMMINS-Dodge-RA...d7a9a3c&vxp=mtr

Like this thread is about, I would want quick spool and HP!

All the Best,

Boucher'

Have no info on those turbo's.
You guy's have to remember. HP is made by holding TQ to a higher RPM. Turbo engines produce higher tq #'s at lower than peak RPM. I like to think of adding boost as a TQ multiplier. Each Pnd of boost will give an approximate 5-10% increase in TQ. So if your engine makes 250 ft lbs and you give it 5 PSI. It could be putting out 375 ft lbs with the boost. HP will increase but not substantially like TQ.
An engine thats boosts at low RPM like 2000 might be terrible to drive. At highway speeds it will be on the verge of boost at all times. Bad for mileage.

I am not an expert but I will throw in my 2 cents.

I believe that HX40W has a good size compressor for your size engine, but to know more about it we need the compressor size, turbine wheel specs, & the A/R of the turbine housing.
I believe the turbine housing will be too big, like 16 CM or larger maybe 19 CM ,if so that would not be good for fast spool up.

I do not think it will spool super fast on a 250 CI engine, because I am thinking the A/R on the turbine housing is a little bigger.
Just guessing of the A/R to be equivalent .84-.96, or 1.10 range (as just a guess)
And guessing the compressor wheel size of 58-60 MM?

That turbo should give you some good HP & be able to boost pretty high.


If you want fast spool-up with that turbo you would need an A/R of 8-10 CM for your 250sized engine.
A 12 CM housing, will not be too bad for spooling up quickly.
A 14 CM A/R is real laggy on a bigger 4.3 liter/262 CI engine.

Hope this helps somewhat, but like I said, we need to know the exact specs of that turbo.

Just remember, there is a tradeoff of spooling & more HP.
Quicker spooling usually means a smaller A/R/smaller turbine housing is needed, but with that smaller A/R turbine housing, it chokes off the breathing of your exhaust.

I want to learn more/experiment about running a larger turbine wheel,but use a somewhat smaller A/R turbine housing so it will not choke up the exhaust so much but be able to spool-up quickly.

As far as internal or external wastegate?

An internal gate is easier to use, less plumbing, but sometimes (depending on size of wastegate valve & design) could cause boost control issues, causes the turbo to slow down some because of proximity of the wastegate valve to the turbine wheel.

I run an internal wastegate on my Syclone, factory style, but w/a ported wastegate hole, no boost control issues running 26 PSi of boost.
But I am improveing the design & am going to devide the wastegate exhaust from the turbine wheels exhaust.

Stock style housings.









Modified housing, The wastegate gate exhaust is separate from the turbine wheels exhaust via the plate devider I made.








MBHD

Cannot see the above pictures? Is it an issue on my part or are they missing?

Sorry... see them now!

I don't know why anyone would use a TO3 other than room problems.

You need to use a TO4 and as Tom said a 60-1 compressor and a "P" trim turbine It's got a nice big map so it will make good HP at any boost level.

I ran one of these on a 270 cu in motor with a 1.2 A/R turbine and it would make boost in neutral, TRY that on most turbos.
It made 514 HP 640 TQ at 5000 RPM. Set a record at 212 MPH.

(Oh by the way it was a flathead) talk about bad breathing !

Nowdays people are sizing the turbine close to 1 to 1 compared to the compressor, for more HP and quicker spool.

At 20 psi on the intake it was 18 psi on the exhaust, perfect!

With the bigger A/R the engine thinks it's N/A .

Small just means stuffed up.

Harry

I was reluctant to post this as I don’t want to beat this to death but I didn’t realize that choosing a turbo could be so confusing!!! (I’m beginning to think it might be easier to but my wife a pair of shoes than select a turbo!!!). Now there may be the “perfect” turbo but I would assume there are many others that are very adequate, especially for my purpose. Its just which ones are these.
I have looked at a couple of dozen or so and find some listed with A/R and some with Trim specs. There also are some terms that I do not know how they relate to the specs. The “T04E” I do understand but not sure what the 60-1 always refers to (compressor trim?). Also the “P” or “Q” trim and how to compare them to the numerical values of other units.
Then there is the T3 or T4, divided or undivided choice. I will be making my own “J” pipe attached to the OEM 292 manifold so I can go either route but the T4 undivided would seem to flow better and produce less back pressure??. (For whatever it’s worth, the SPA manifolds appear to be T3 divided.)

I feel that I am making this way to complicated but my first thoughts was the T04E 60 T4/.81 (not sure about the T3/T4 hybrid) but am having a hard time finding a match while the GT35’s seem to be more plentiful and in my price range of 200.00-400.00 so I may end up with a GT, which would be fine and I am ready to get this decided.

Here are a few of the ones I have narrowed it down to:
Looked at this one but it has a T3 turbine??

t3/t4 t04e big wheel turbo charger .83ar twin scroll

Another one With a higher AR
T4 Turbo AR.60 Cold side, AR 1.0 Hot Side

OBX T04E Turbocharger T4 V-Band Turbo 64 Trim 0.96 A/R

some GT35’s

GT35 T3 Turbine .82AR Twin Scroll Turbo Charger 2.5''

Anti-surge / Ported Shroud GT35 GT3582R Turbo .84 TRIM
http://www.ebay.com/itm/290739630365?ssP...9#ht_5503wt_698

Polished GT35 T3 FLANGE 5 BOLT P TRIM Oil & Water Cooled

Then there is always the HX40 but specs seem to be incomplete but has internal WG and appears to be very popular?

HX40W Holset T3 Internal WG

I know that this may be time consuming but any opinions would be appreciated... Thanks, Jerry

I think if you run any turbine A/R larger than a .84, you will not see much boost in first gear & 4.55 rear gears.

I am on the conservative side of thinking.

A devided turbine housing will spool up quicker.

Out of all the turbos you posted, I think this would be the best one as far as specs go.
http://www.ebay.com/itm/270890219020?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_834wt_698

MBHD

Jerry,

Don't give up, get some books on turbos and it will explain alot, it is very confusing at first. A lot of folks use terms that don't have any real importance like compressor trim or compressor a/r ratio, but on the turbine these are very important.

A GT3582 is a great turbo but if you look at it's map it is better at a higher boost level than what you said you wanted to run.

Both the 60-1 and the GT3582 have about 60mm inducers on the compressor but the maps have different shapes. The map of the 60-1 is called the potato because it's shape is so fat at low boost pressure.

The inducer size is what everyone talks about because it kind of determines the HP the turbo will make, but its a talking point not the complete story.

I will post some books that I like Tommorow.

Harry

Thanks again for the responses... I have the book by Leo Santucci "Chevrolet Inline Power Manual" which is a super book and is what got me started thinking "Turbo". (I knew I had seen Turbo-6's avatar somewhere else). The chapter on turbocharging is good but of course very general as he could not cover everyone's setup. I'm aware of the book called "Maximum Boost" by Corky Bell and will try and find it. I have read numerous articles on the internet(!), and most agree with each other, but sometimes written for a particular motor (Honda, etc) and not suited for the 292. I's seen the maps for the T04E-60 and that is what best matched by needs and will look for the GT35 maps. In looking at the specs I guess that its the different combinations of inducer/exducer sizes between the turbine and compressor that creates the most confusion. Will keep looking...Thanks, Jerry

Let me correct myself first, the disco potato turbo is a garrett GT2860RS, but the map of a 60-1 looks a lot like the garrett and goes to a higher HP level.

The books I like are:
Maximum Boost by Corky Bell, Robert Bentley Publisher
Turbochargers by Hugh Macinnes, HP Books
Turbo Real World High Performance Turbocharger Systems by Jay K. Miller, SA Design.

Harry

Here is the compressor wheel of the disco potato

http://www.ebay.com/itm/Brand-new-Perfor...f17312e&vxp=mtr

47.2mm inducer is pretty small.

MBHD

I ordered the “Maximum Boost” and should have it by Friday at the latest and expect it will answer a lot of questions. Had seen references to the “Disco Potato” but didn’t understand what it meant… Thanks for the explanation.
The T04E-60 map was the first that I had looked at and still looks like a good choice. I have seen a lot of T04E’s that are T3/T4 hybrids, are these OK or is the T3 to small for my 292? I assume the T3 is the turbine? Just another area of confusion! I have been looking for compressor inducer sizes of around 62mm and turbine exducer of also around 62mm and trying to find maps to match and also thought the 47mm would be to small.

I Started looking at these maps and made these comparisons.
http://www.not2fast.com/turbo/maps/

The GT30R 76.2mm 56 trim, 0.60 A/R would also appear to keep my 1.68PR and 24-28LBS/MIN in the 78% area but the center is not as fat as the T04E-60.

The GT28RS 60mm, 62 trim,.6A/R slips out of the center area at 1.68/28.

The GT35R 68mm,56 trim,.70A/R works but has a much narrower center.

With everyone’s helpful input I probably could make a decent choice and not be too far off but guess I will wait until I have a chance to review the Maximum Boost book.

Thanks, Jerry

Study the maps don't get stuck on size only.

T3 T4 etc. are the bearing housing size of the turbo , also either 3 or 4 bolt flange. the T3-T4 hybrid is a T3 modified to fit larger wheel.

Harry

Thanks again... So in looking at a T04B the T3/T4 hybrid is possibly of little concern from a performance standpoint(?)and I assume the 3 or 4 bolt flange refers the bolt pattern where the bearing housing bolts to the turbine and compressor.

FYI... sure I'm the last to find these and don't know how accurate the online calculators are but found this one and tried to plug in my numbers best I could and it lets you select different maps. The T04B-601 map looks very good. Calculator Here


Jerry

The 3 or 4 bolt flange is the turbine housing where you bolt up your exhaust to, where the exhaust enters the turbine housing.
The 3 bolt pattern does not flow as good as the 4 bolt flange.

They are somewhat the size of a T3 housing.

MBHD

Jerry,
That's the one Tom Lowe told you about 8 days ago ! And the one I used to first get in the 10's it's a good fit for many cars.

Harry

Well I guess I should have paid more attention early on except I guess I was just filling one of my quirks of wanting to dig and find how things work. Now I will keep focused on the T04B 60-1 and try and find one in my price range. The map for the T04B 60-1 clearly shows it will flow as I need and the graph in Corky’s book states that a 2.3-2.5 turbine exducer wheel would be correct but still not sure about the compressor wheel size. What I am finding with the correct turbine is a compressor inducer of around 54-56mm. Not sure if that is too small. Any thoughts?

TO4B 60-1 compressor is 59.5mm-2.34" inducer, 76mm-3.0" exducer

Harry

As I stated in a previous post a 57 MM compressor wheel will work fine. A 60-1 will work fine also.

A 60-1 compressor wheel is a bit big to run only 10 psi max.
Also, with a larger than needed compressor wheel causes the turbo to spool up slower (it is heavier). It's also trying grab a lot more air whichs makes it harder to spool.

But @ the same time when I installed the larger 60-1 compressor wheel over the standard 20G wheel, it seemed to spool about the same, just a hair slower, but.... when it sarted grabing some boost it came in really hard & fast!

I run somewhat of a small turbine housing so the streetability is not affected too terribly.
It has a 12 CM turbine housing which is about a .63 A/R.
And.. w/having an engine of 262 C.I's 8.4:1 compression & a .63 turbine housing, it is a bit laggy,& also, I have to dip into the trottle pretty good to get into boost on the freeway in OD w/3.42 gears 3600 + lb truck.

It does not go into boost unless I dip into the trottle pretty good.
In park/neutral, my turbo can get 5-7 PSi by 4700RPM when I floor it.

I have done a lot of testing w/different turbine housings w/different A/R's.
Current turbos timeslip. Not the best, but I think it's pretty good for a 3600+ lb truck on 91 octane. Et is the rht side.
My RT was slow, just made sure I was boosting where I needed to, (running my own race) by chance I still ran down a turboed Honda.
It was extreemly lean 13.8 A/F ratio because my methanol injection was not pumping enough. I am pretty sure it died during that pass.
Luckily, I had my J&S controller, believed it saved my engine that run.
http://www.jandssafeguard.com/


I am not willing to sacrifice driveability to gain top end HP so far, my Syclone is a street truck not a drag truck.
So my main emphasis is to boost faily easily (not the best mind you) w/out overly plugging up the exhaust flow through the smallish turbine housing. Hope you get my point.

Here are 3 of the 4 different turbine A/R housings I have personnaly tried out & used on the street & track along with using my Belltronics Vector FX2 Performance timer/ Accelerometer tool.

Lft to RHT 14 CM, 10 CM, & 8 CM.
I currently run a 12 CM turbine housing, the 12 CM is a bit restrictive, but going to a 14 CM, makes it hard to spool up quickly & overall driveability is the pits, mainly because my torque converter is rated to stall only to 2100 RPM.

All the turbine housings have internal wastegates & all do control boost good as long as you port the wastegates hole larger to flow more than originally. Mind you, I run up to 26 psi w/this turbo & it can control boost just fine.

I use a AEM TRU boost controller which works great.
http://www.aemelectronics.com/tru-boost-boost-controller-gauge-757







A 54-56 MM compressor wheel will work fine for 10 PSI.

Just as a reference, the stock compressor wheel of the Syclones & Typhoons 4.3 liter 262 CI engine has a Inducer: 48.3 mm w/a Exducer: 68 mm

Stock boost is 15 PSI.

Guys have run as high as 25-27 psi w/a stock turbo & a lot of methanol (not recommended to do so)just saying.
At anything over 18 psi w/the stock 48 MM compressor wheel, the air is getting really heated up & not in the efficiency range @ all.

I like running a semi stock looking turbo on my Syclone & stuffed a 60-1 compressor wheel in the turbo.
Now, I run up to 26 psi of boost pressure.

Stock turbo on top w/a 48.3 mm inducer, 60-1 wheel on bottom pic.


60-1 wheel on the lft, stock on the rht, Stock 48.3 mm wheel = whimpy.


I am currently on the quest of searching for a larger turbine wheel for my Mitsubishi turbo, hoping to use a modified Garrett turbine wheel machined to fit in my center cartridge.

I believe it is just a bit small.
Also, trying to reduce the number of turbine blades, currently is has 12 blades, looking to @ least drop down to 11 blades or 10 turbine blades. It's really choked up in the turbine wheel area.
Specs are DIAMETER 58.8 / 67.14 mm ,= whimpy

MBHD

Thanks and as it is said “a picture is worth a thousand words” and all the associated post with bunches of info. Undoubtedly this will reduce the changes of making a poor choice. I think that I am starting to understand some of these many variables that define the performance and selection of a turbo but there is always something new that pops up.

I understand the A/R as expressed in numerical values (.68,.84 etc) but having a difficult time finding the true meaning when expressed as 10 CM, 12CM,14CM. etc. I know this relates to the size of the turbine housing but do not where or how it is measured. I can see by the pictures, that a 14 is a larger housing than a 10. I assume its volume of cubic CM? What I have found on the internet(?) is that a CM 14 equals a .80 A/R and a 12 CM equals a .70. If this is accurate I do not know.

I also understand how “trim” is calculated and some of the effects it has on performance. In reviewing Corky’s Bell “Maximun Boost” I cannot find any references to “Trim”. I find this strange, hope I haven’t overlooked it, but is trim not a major factor?

Some references to the T04B 60-1 indicate that the 60 refers to the size of the compressor inducer (59.5mm) and others identify it as the trim? Have not found what the -1 stands for and may not be significant.

All this may sound frivolous but I like to try and understand as much as I can.

Thanks, Jerry

Jerry, I have not ever seen 14 cm either, MBHD what does it mean? 14 centimeters is like 5.5 plus inches.

Trim is not needed unless you don't know one of the wheel sizes,all you need is the wheel sizes inducer and exducer for the compressor and turbine and the A/R ratio of the turbine.

More important you just need the maps to get close.

The -1 is not important.

I still stand by, if it is only for the street and not drags a big A/R works better, since the engine thinks it's NA until under boost, Big A/R will work on a drag car if it has a lot of stall.

Small A/R is old school.

Harry

Here is one on ebay.
http://www.ebay.com/itm/Turbonetics-60-1...9de8bcb&vxp=mtr

Just so you know, you can have a huge 1.44 A/R T6 turbine housing, it will flow like crazy exhaust flow like N/A, it will never see boost in your 292 you build.
I take that back, it will boost waaaaayyyy late!

Douglas ran a (IIRC) 15.7 @ 135 MPH w/a huge T6 turbine housing in his drag car. It did not get into real boost until 1/3rd of the track was already past behind him.

Main problem was his camshaft he was running, but even w/a camshaft change for the better, it still could not build much boost from the start.

Guys have run bigger than stock turbos & ran .84 -,96 A/R turbine housings on a stock Syclones & Typhoons & all & I do mean all ,have run slower times mainly because they could not boost off the line as they could w/a much much smaller turbo.

You got to be able to boost it in the lower RPM range, or you will not like driving your turbocharged 292 on the street.
That I will guarantee.

If you run a "big" A/R on the street it will not make a good low RPM boosting daily driver.

.63 A/R will be perfect but run a "Q" trim turbine wheel. A "P" trim will work also.

Just my two cents, take it for what that's worth.

All the numbers for the Mitsubishi turbo A/Rs are how they size them. Metric.

A 12 CM is about a .63-.68 I believe.
A 8 CM is about a .58
I thought a 14 CM is .84-.94 range.
I am searching for a website w/more info on this subject.

I do know w/a 262 CI engine & run a 14 CM turbine housing, Syclones & Typhoons need a 2600-2800 stall converter to get it to spool up decent.

Also, if that 14 CM is actually a .80 A/R, you are really not going to like a .84 A/R turbine housing & expect it to start boosting in the 1600-1800 RPM.

Goodluck though if you do decide to use a big A/R.

I can also say, when using a stock turbo w/a 8 CM turbine housing (same as a .58)it made for a really kick in the butt daily driver low RPM boosting engine a absolute blast!

I run a 12 CM, & I can tell you, it boost's later & in general, it is not as fun waiting for the engine to get into boost.

MBHD