Inliners International Forums General Discussion Blown and Injected Turbo JED, new turbo? upgrades? am I crazy?

Inliners,

It has been encouraging to see the increase in people wanting to Turbo their inline. In the quest for more efficiency, power, and a longer black mark, I have been thinking about upgrading my system.

I have been kicking around the idea of a new:
- air to air intercooler
- 292 exhaust manifold
- offenhauser intake
- new turbo

The first three are straight forward, but the fourth item is not. Turbo sizing is even more complicated that camshaft selection and that made me cross-eyed!

What do you all think?

I always do come back to the saying, "if its not broke, dont go fixing it"

This is a turbo for sale locally, that would actually bolt right in!

http://nashville.craigslist.org/pts/3409715811.html

All the best and happy wrenching!

Boucher'[i][/i]

Do it! Then sell the older stuff to me! :P

But in all seriousness, if you can support it (current drivetrain) then do it.

Haha!

TLowe said that if I just do an intercooler, I can kiss my tranny and then rear end goodbye!

BTW, I have a stock rear end and NWC T5 tranny.

Boucher'

Well, if you go any bigger I'm sure you'd have to upgrade that. I'm looking into an Impala rearend (posi trac) and gritting my teeth. Those babies are expensive!!

If you dont speed shift & side step your clutch pedal while gas pedal floored, your tranny & rear should be fine.

Might be looking into a different rear axle, for later to beef up the drive train.

I do not know what size turbine wheel is in that Turbonetics turbo, if it is a stage 5 or "P" trim that will work fine for your 250 engine. Need to find out, most likely it has a "P" trim turbine wheel.

The .63 A/R on the turbine is good, any bigger, forget about boosting much below 2800 RPM.

Don't let the someone tell you to get a .96 or larger turbine housing A/R. I can tell you right now, you will not like it for a street truck, a .84 & larger A/R will give you a lot of turbo lag.

It also depends on if you want power down low & mid range, or you just want mostly top end power.?

I have brand new Turbonetics large valve T3 wastegate assy if interested. Need to weld a couple things to be usable though.

Forgot what intake you have now?


MBHD

I would rather have low/mid power, especially with the low rev 250. I have to shift really quick.

I have the stock intake manifold bored out to the "oval" size of the 2bbl carb.

OK,
your intake, carb & exhaust manifold are really restricting you from making more power.
You would make more power by using a 4 bbl carb about 600 CFM.

A intercooler will make a significant improvement & will allow you to boost much higher than you are currently.

Adding methanol injection is like running race gas & allows for more boost & timing.
The turbo is a T3 made to bolt up to a GN Buick.
That style 3 bolt T3 does not flow as good as a 4 bolt flange T3.

You are using a 350 CFM 2 bbl Holley , correct?

MBHD

[quote=Boucher
I would rather have low/mid power, especially with the low rev 250. I have to shift really quick.

I have the stock intake manifold bored out to the "oval" size of the 2bbl carb.


[/quote]

If I read that turbo right, it is a 61mm, I wonder if it is realy a 60mm T3/T4 hybrid. A true 61mm will have a T4 exhaust housing. Price is high enough for used parts.

I suspect it may be big on the compressor side and small on the exh side.

The T5 5 speed has a tq rating of either 300 or 310. That 250 will certainly produce that much tq with a good turbo setup. Heck in N/A form , it can make 250-275 tq. Add 10% tq per PSI as a quick reference.
The rear in that Chevy should be a 12 bolt unit. It is plenty strong. To a point.

I'd like to see a Turbonetics 60-1 P trim with a .82 exhaust housing.
You would also do better with a auto trans.

What about this one? http://www.ebay.com/itm/1986-1987-ATR-TU...d5df9db&vxp=mtr

Thanks for the valuable info...

Ok, lets say I have $400 to spend on the upgrades.

What is a bigger bang for buck?

1.) intercooler ($200) and a Offy intake ($200)

or

2.) intercooler ($200) and a 292 exhaust manifold ($200)


boucher'

Meet in the middle and get the intake/exhaust and save for the intercooler in a few months :P

I like Alex's idea. Get the intake and exh manifold. Get it back running and save up for a bigger carb and intercooler. Then top it off with a better fit turbo.

I do not like your limited choices here.

But, your carb is one of a limiting factor, 350 CFM, correct?
Intake next limiting factor.
I like the Offy intake because of the 90 degree corners, I am thinking it will distribute the air/fuel mixture better than a Clifford, especially when blowing through a carb. 2 cents.

I would like to see a engine dyno testing the A/F ratios to each cylinder when blowing through a carb & do a back to back comparision between the two intake manifolds.
Would be interesting to find out .


Best bang for your $400, intake ,carb, & exhaust manifold, intercooler add later.
MBHD

Also, adding a methanol injection kit will allow you to run more boost, timing on your current turbo you have now.
The turbo you currently have can provide 20 PSi, you are not close to that yet, but,,, do not attempt to w/out an intercooler or methanol injection.

Thanks for the input.

I just went to take a gander at the engine bay. I don't have the energy or patience to re-do the up-pipe and down-pipe that is associated with a new exhaust manifold. It took me forever to make those two pieces just because the clearance was +/- .5" in some places.



I am on the hunt for a OFFY 5416 intake.

Onward and upward!

Boucher,

Not sure if your exhaust manifold has an alignment tube that is about 2" or smaller? It is a restrictor IMO.

IIRC, my moms 73 Nova had one, I removed it & did some opening up on the exit of the exhaust manifold to breath better.

Could have been my 65 Malibu 283's manifolds?

You can do the same w/grinder & carbide tips to improve exhaust flow, won't cost anything, just your time.

Grind down any sharp edges & try & picture how you can make the exhaust flow better. A more straighter path.

I believe I mentioned to you before,, the wastegate's 90 degree exit from your turbine wheel is really restrictive & will cause your turbo to spool slow.

If you do ever change your downpipe, look into a straighter exit of the exhaust from the turbo. Also, make it a full 3" downpipe, it does make a difference on how fast the turbo spools up.

Even if you have only a 2" turbine wheel, the better flowing exhaust, no baffles in a muffler, etc, make for a quicker spooling turbo.
Only drawback of running 3" & larger downpipe, is it gets a little harder to quiet it down, but it can be done.

MBHD

Hey Boucher, there was an Offy intake for sale over on the truck board for $160 last week.

I know.... Now it's mine!

I was so excited to see Santa come to my door today and deliver this:

Woot!

Sweeeeeeet!

I finally got the chance to dig in today. The turbo looks in great shape, as well as the up and down pipes.

When I took off the intake/exhaust I was revealed an issue. I had noticed oil/gas stains coming down from that area and running down the block. I kept on trying to clean it up but could never see the source.

It looks as though the intake was not tight against the block and fuel was leaking from the intake and down the block. Probably caused from running rich and boost pressure.



I am taking my Offy and exhaust manifold in to get resurfaced, hopefully that will correct the issue.

Boucher'

I don't like those soft gaskets and I don't have a turbo and get the same results with slobbering down the side of the motor. I started using the combo gasket with thin metal and thin garlock type gasket. I coat both sides with that red Hi Temp RTV and tighten the hell out of it and then forget it. There must be some movement between the alloy intake and cast iron exhaust that don't match. I leave the three mating bolts loose that hold it together till every thing has warmed up then snug them up....Works for me.