Inliners International Forums General Discussion Engines More Torque for 250 LD4

Hi,

this is my first posting here, so first some infos about me:
I’m 45 years old and life in Germany near Frankfurt.
In my normal life, i work as a IT process manager and developer.
I have a 1978 Chevy C10 with a 250 LD4 engine, this is my first US-car. Before that i drove old BMW, and repaired them. But i‘ve never tuned them (only a bigger engine 3 times, or another intake).
Now i‘m interested in getting more torque from my engine.
I‘m not a RPM- friend, the more torque at low rpm the more i like it.
I didn‘t found much info about this engine, only the HP and Torque at https://www.cjponyparts.com/resources/1978-chevy-truck-specs

Now my question is, how to get more torque.
The 1970 250 has more hp and torque and as i understand, the 250 mercruiser engine also, but didn‘t found too much info what they did when they circumcised the engine for emission control. Only that the old engines has a better compression ratio.

I‘ve found these pistons: https://uempistons.com/i-17060-4-1l-gm-mercruiser-l6-uses-2m667-040-piston-set.html
Looking at the specs, I see a better compression ratio - 8.4:1

So is is as simple, only put these pistons in and the engine is more like a 1970 250 with more HP and torque??

What i also want to change is the exhaust, 12bolt has a nice split one, and with it, i change into 2 pipe til the end.
Then i‘ve bought a lump kit (it was cheap because of changing to a newer version)
My thought is, that it can‘t be false if the engine can breath a bit better.

Okay, have a nice day and stay healthy!

Regards
Chris

Edit:
The engine has a non integrated head, is that usual or allready changed by a previous owner?

Most of the information here is for race or hot street engines but there is some truck information. I am putting parts together to build a 292 for my '68 C20 flatbed. The idea is the same for a 250. Jalopy45 here is building a 250 for hauling and towing. The search part of this website doesn't work well. The easiest way to find the threads would be to to look up our posts histories by clicking on our names and then going through our posts.
12 Bolt sells a good low end torque cam set. You can read our discussions about head work. Try looking up these threads. Best 292 truck Cam? & Lump Ports in a Work Truck

Welcome to the site!

Hi,
thank you for your answer and info.
I‘ll check your threads!

Regards
Chris

Let us know what you learn and what you decide to do. I hope to get my 292 together this winter. A friend loaned me a '46 two ton dump truck that he had put a stock 292 into. I hauled many 7 yard loads of gravel up a steep dirt road. The engine pulled like the truck was empty. I am replacing a worn out 350 V8 and looking forward to enjoying my '68 again.

Chris:

I don't know if you saw my thread on modeling a 292 inline six, but I think I now have a somewhat representative model working. I would be cautious to read too much into the model, but I think one thing the model responds well to is upping the compression of the 292. The effect of raising the compression raises the torque across the entire RPM range and does not hurt the low end.

Regards, Cris

More compression is more power all around in alot of cases. But you have to watch how high you go Do to octang ratings. The cam can change the compression some depending on the over lap.

You can always put a blower on it, that never hurts.

+1 on what mick53 wrote. Any boost for that matter. With an SPA manifold and a 'less expensive' turbo...the packaging of an inline lends itself to a relatively simple install. The cost is not that bad either.

Also...
The ways to positively affect torque are displacement and bang.

T=PLA

T is torque
P is pressure
L is length of stroke
A is bore area

15 LBS of boost or a 100 shot(SWAG) of nitrous will theoretically double P and therefore double torque.

Regards,
Rick

Hi,
Add a blower (think you mean a turbocharger or compressor) is not possible for me. In Germany are some rules for old cars. They have to be nearly original for a special licence plate(okay what they don‘t see, they don‘t know). Otherwise I can‘t drive in bigger cities and the car taxes are horrible.

Thank you all for your hints to your threads, i‘ll read them and with these infos i‘m shure to reach a good way for more power!

Regards
Chris

Have a nice day

Can you use nitrous without incurring penalty? Granted it kind of only applies to wide open throttle but nitrous will get you onto a highway, pass a vehicle, or get from stoplight to stoplight a lot faster.

Regarding boost...by using ~one atmosphere of boost, the theoretical math is easy. That's why I chose that example.

I see you didn't read the article.

Have a nice day

Hi Panic,

Alas, as of yet, I have not. I was too busy justifying my writings ;-).

I spent a bit of time in Long Island (Manhasset,Wantagh) in the 80s. It was beautiful.

Cheers,
RJ

Hi Panic,

Yes...

That's why I stated theoretical. I didn't think that much detail was germaine to my post.I wanted to keep it simple. More torque requires bigger displacement and/or bigger bang (lots of stuff makes bigger band happen). Yes there is stuff that is not the friend that torque increase but that doesn't change what is required to add more pounds of pressue to the end of a lever of static length.

Thanks for keeping me honest.