What if: Building an Inline Six Torque Monster

[Oberon67]

So I've got this 1981 C10 longbed in pretty good barn-fresh condition, body's solid and it runs pretty well. (It's currently in the shop getting the Varajet carburetor and a vacuum leak sorted out, but that's another story.) The transmission is the venerable Saginaw 3-speed.

Let's say I wanted to build an engine for it as an exercise in getting all possible torque out of a GM inline six. Engine could bolt to the current transmission or I could swap in some other manual.

I would find for myself a clean rebuildable 292 core. What next?

[Oberon67]

My chief interest in this would be to improve on-the-street driveability. If I did a transmission swap its purpose would be to help keep the motor in the fat part of the torque curve as much as possible.

[Warrens69GMC]

Turbo and five speed.

[Oberon67]

Originally Posted by Warrens69GMC

Turbo and five speed.

If I were going to put a blower on it I would think a supercharger rather than a turbo. Better low-end. No?

In any event, I was thinking more normally-aspirated.

[Tom]

Ebay and china have made turbo's massively cheaper to add then a supercharger. When it adds boost depends on what size turbo you choose.

There are limited inline6 parts, so any performance I6 thread will give you all the info you need for bolt ons [I don't know them off hand].

[Oberon67]

Originally Posted by Tom

Ebay and china have made turbo's massively cheaper to add then a supercharger. When it adds boost depends on what size turbo you choose.

...and the volume and flow rate of the exhaust, which whatever it is won't be much when you're just off idle.

You would really have to convince me that adding a turbo was worth it for the additional low-end torque it would produce.

[Valarius_Starchaser]

http://67-72chevytrucks.com/vboard/s...d.php?t=653268

Supercharged I6 build if you needed some ideas this was very well done and is complete different years obviously

[slotard]

Originally Posted by Oberon67

...and the volume and flow rate of the exhaust, which whatever it is won't be much when you're just off idle.

You would really have to convince me that adding a turbo was worth it for the additional low-end torque it would produce.

The right size turbo can certainly spool well before 2k, lots of current production cars do. Harder to also have top end with standard turbos, though.

[Warrens69GMC]

https://www.youtube.com/watch?v=fz2UaM3i-gQ

[MikeB]

That Saginaw 3-speed trans probably has a 3.50 1st gear, which won't handle a lot more torque than a stock 250 six makes. But you could get a new gearset with a taller 1st gear. The 292 used a 3.11 1st gear; the 305 a 2.85 I think. The taller the gear ratio, the more torque the trans can handle.

I'm not sure about your 81, but my 82 250 came with the standard 2.73 axle, which doesn't quite cut it with a 3-speed manual trans, even if you could get 275 lb/ft torque from a 292.

If you have the dreaded integral head/intake manifold, it's gotta go.

Check out Clifford Performance for parts.

[Blessed66]

Originally Posted by Oberon67

You would really have to convince me that adding a turbo was worth it for the additional low-end torque it would produce.

This is gonna sound kinda bad either way I phrase it, but why would we need to convince you?

A brief look at automotive history will show how far the turbocharger and turbocharging technology have come, how much more popular it's becoming, etc.

You can package the system any way you want it (including remote mount), you have plenty of systems on the market to tune it however you want it, and there is no way anyone can deny turbos can make some amazing power (Nelson, for example, offers a twin turbo small block making a dyno-checked 2500hp, 2000 lb/ft pull in "race trim" and 1500hp, 1400 lb/ft in "street trim" for a cool $52k).

The only limits will be your engine, your wallet, and your sanity.

That being said, they're amazing. Once the boost bug bites, there is no going back. You'll turbo your lawn mower.

tl;dr Go turbo, do some research, don't be afraid to ask questions - you can thank me later.

EDIT - And for the record, assuming this was my engine, I'd go sequential turbos... smaller, faster spooling turbo for immediate off-idle boost and a big boy that kicks in around 3000-3500 rpm.

[Oberon67]

Guys:

Originally Posted by Oberon67

My chief interest in this would be to improve on-the-street driveability.

Were I to build anything at all, it would rarely see the north end of 3500 RPM.

[D13]

How much money do you want to spend?
1) bottom end grunt for pulling?
2) Quick revving for performance?
3) Gobs of HP up top?
4) max fuel economy?

First buy the Second edition of Santucci's book and join Inliners.

If you are looking for low speed driveability out of the generation of inlines in our trucks, get rid of the integral head, put on a head with 1/8 intakes / 1.6 exhaust, lump ports, 307 (higher compression) or forged pistons, and the 'marine' cam that makes a little more grunt than stock, Langdon's iron headers, Offy intake and 390 Holley.
More torque with less economy, use a 292 as the base (they aren't efficient but they really pull).
Good economy and some hard pull at upper RPM, use the turbo exhaust mainfold with a small T4 sized to hit at 2500rpm (above cruising RPM) and switch to TBI (better fuel mixing).
Blowers are $$$ and the block is the limiter (fails ~700HP).

Remeber these motors are antiques. If you want it to drive like a modern vehicle you will need to swap the motors, either LS or 4200 Atlas, or spend a whole wad of cash.

[Oberon67]

Originally Posted by D13

First buy the Second edition of Santucci's book and join Inliners.

If you are looking for low speed driveability out of the generation of inlines in our trucks, get rid of the integral head, put on a head with 1/8 intakes / 1.6 exhaust, lump ports, 307 (higher compression) or forged pistons, and the 'marine' cam that makes a little more grunt than stock, Langdon's iron headers, Offy intake and 390 Holley.
More torque with less economy, use a 292 as the base (they aren't efficient but they really pull).

This.

THIS is the advice I was looking for, and thank you.

So much is gained when people read and understand the OP...

[daddyjeep]

Check these guys out too. All they do is the inline 6 engines.

http://www.shop.cliffordperformance....250-292_c4.htm

I researched them years ago for the Jeep engine, but went V8 anyway so I never bought anything from them.

[Tom]

Originally Posted by Oberon67

So much is gained when people read and understand the OP...

I love the underhanded slam of everyone else who tried to help in this thread just because they didn't have a specific combo suggestion, along with the refusal to believe what everyone was telling you about turbo's. Thanks for the lol's.

[Valarius_Starchaser]

Originally Posted by Tom

I love the underhanded slam of everyone else who tried to help in this thread just because they didn't have a specific combo suggestion, along with the refusal to believe what everyone was telling you about turbo's. Thanks for the lol's.

No kidding

[Blessed66]

Originally Posted by Tom

I love the underhanded slam of everyone else who tried to help in this thread just because they didn't have a specific combo suggestion, along with the refusal to believe what everyone was telling you about turbo's. Thanks for the lol's.

You know what they say. You can lead a horse to water...

For the OP, I've always found that if you plan to build to a very specific direction but cover all bases (and directions) along the way, the outcome is far more satisfying. But it's your stuff, do what you want.

Hope it works out.

[Oberon67]

Originally Posted by Tom

I love the underhanded slam of everyone else who tried to help in this thread just because they didn't have a specific combo suggestion, along with the refusal to believe what everyone was telling you about turbo's. Thanks for the lol's.

Well, what can I tell you?

I post that I'm interested in building a six for low-end torque to improve on-the-street driveability, and I get feedback talking about turbos that kick in "around 3000-3500 rpm."

One or the other of us wasn't communicating. It's entirely possible that I don't listen worth dung, it's true. It's also true that I began the thread with some preconceived notions in mind that perhaps I didn't state properly up-front. If that's the case, I apologize.

[Blessed66]

Originally Posted by Oberon67

I post that I'm interested in building a six for low-end torque to improve on-the-street driveability, and I get feedback talking about turbos that kick in "around 3000-3500 rpm."

Not understanding what my idea means does not disqualify it as a valid idea - or are you going to say next that Toyota Supras (Inline 6, sequential turbos) don't have good on-the-street driveability.

I'm a fan of all good engineering ideas, except BMW. They tend to over-design and solve problems that didn't really exist. Still, they have cool technology.

Originally Posted by Oberon67

One or the other of us wasn't communicating. It's entirely possible that I don't listen worth dung, it's true. It's also true that I began the thread with some preconceived notions in mind that perhaps I didn't state properly up-front. If that's the case, I apologize.

No, I got your idea. And if you had preconceived notions, that's fine as well. I simply wondered how in the world, in 2016, you still had to convince people that turbos were a great idea - that's all.

[Tom]

Originally Posted by Oberon67

Well, what can I tell you?

I post that I'm interested in building a six for low-end torque to improve on-the-street driveability, and I get feedback talking about turbos that kick in "around 3000-3500 rpm."

One or the other of us wasn't communicating. It's entirely possible that I don't listen worth dung, it's true. It's also true that I began the thread with some preconceived notions in mind that perhaps I didn't state properly up-front. If that's the case, I apologize.

Nobody said anything about using a turbo that kicks in at over half the max RPM of the motor. Thats where you keep taking the turbo discussion even though we tell you different.
Use a small enough turbo and plumming and you'll make boost at 1000rpm. It probably won't make power past 4000rpm but theres your low end. It can and is done on a daily basis, for many decades.

[Oberon67]

Originally Posted by Tom

Nobody said anything about using a turbo that kicks in at over half the max RPM of the motor.

Beg to differ:

Originally Posted by Blessed66

EDIT - And for the record, assuming this was my engine, I'd go sequential turbos... smaller, faster spooling turbo for immediate off-idle boost and a big boy that kicks in around 3000-3500 rpm.

Now this, on the other hand, is a recurrent theme in this thread:

Originally Posted by Tom

Use a small enough turbo and plumming and you'll make boost at 1000rpm. It probably won't make power past 4000rpm but theres your low end. It can and is done on a daily basis, for many decades.

I told you I was going to need some convincing, right? Well, consider me convinced that a turbo isn't a stupid idea.

[Blessed66]

Originally Posted by Oberon67

Beg to differ:

*sigh*

Let me just point something out...


EDIT - And for the record, assuming this was my engine, I'd go sequential turbos... smaller, faster spooling turbo for immediate off-idle boost and a big boy that kicks in around 3000-3500 rpm.

Since the hanging point you've had is "3000-3500rpm" without, apparently, getting the rest of it.

[Oberon67]

Originally Posted by Blessed66

*sigh*

Let me just point something out...

Peace, brother. Forgive me, and let's be done with this. Please.