Some pieces of the puzzle

[Big Bore]

Big Bore,

I was under the impression you were wanting to start to work thru idea to cover everything with this engine build and bouncing it off the choir so to speak. I was just trying to kick it off for ya with a initial list to generate some discussion that would hopefully be of benefit in terms of ideas to include/exclude from your build or confirm for yourself you had Is and Ts dotted and crossed. I do not want to side rail your thread with this stuff if its not of any benefit to ya.

Hey, Tarm.imp: Yea man, good questions all, it was late and i was tired and worn out from a long weekend of training, and you shotgun blasted me. No fault on your part or anything against you, I was just making fun of, and trying to express here, my initial reaction when I read it last night. Which was, "damn, was that in English and what was the name of the book?"LOL

Drinking coffee now and enjoying the sunrise, I'll be reading over your questions and commentary in more depth this morning. However, you did mention something about barrels and gas ports that caught my eye, despite my compromised state of reading comprehension.

Also, two other interesting conversations have come up, surface treating after cryo and the torque issue. Please all continue, nothing is being derailed here because it was really show and tell to start with.

 

[CurtisF]

I'm sorry, but isn't the point of compounds to make a lot of power down low and pull it out through the top as well? In my opinion, it's kind of an oxymoron to have a fuel/torque limit and compounds. Seems like a bigger single would be more than enough for a limited strength bottom end.

I am curious about the low end torque question though.

Like TARM said, you still want to limit torque at the bottom end. Regardless of the number of turbo's you're running, that's still going to completely depend on the fueling in the tuning.

Remember that Big Bore lives way up in the mountains. He's trying to put together a truck that makes some good power, but keep it street-able at very high elevation. That's just not going to happen with a large single. You can get away with it at low altitude, but I guarantee that won't fly where he lives. Even a 38R displays some very noticeable lag when you get up in altitude.

Going with compounds isn't meant for gobs of low-end torque that will rip the motor apart, it's meant to keep turbo lag at a minimum. That way you don't blot out the sky, kill a polar bear, and club a baby seal each time you take off from a stoplight while you're waiting for you big single to finally spool up.

 

[Big Bore]

Compounds are more for allowing you better top end and midrange power, mostly top end. Instead of swapping out your smaller turbo for a larger, you simply "stack" a larger one on top of the small one, so you can maintain the response of the small one, and gain the mid range and top end of the larger, without the lag and smoke penalty like Curtis mentioned above. Of course there will be an increase of bottom end, but the more substantial gain is up top.

And like Curtis said, it's all in the tuning, if you know how.

 

[CurtisF]

so you can maintain the response of the small one, and gain the mid range and top end of the larger

That too. :blitzed:

 

[JAP]

Like TARM said, you still want to limit torque at the bottom end. Regardless of the number of turbo's you're running, that's still going to completely depend on the fueling in the tuning.

Remember that Big Bore lives way up in the mountains. He's trying to put together a truck that makes some good power, but keep it street-able at very high elevation. That's just not going to happen with a large single. You can get away with it at low altitude, but I guarantee that won't fly where he lives. Even a 38R displays some very noticeable lag when you get up in altitude.

Going with compounds isn't meant for gobs of low-end torque that will rip the motor apart, it's meant to keep turbo lag at a minimum. That way you don't blot out the sky, kill a polar bear, and club a baby seal each time you take off from a stoplight while you're waiting for you big single to finally spool up.

Ahh yes. I forgot about your elevation.

 

[Big Bore]

Even at low elevation I don't think you are going to tow heavy with a large single.

 

[Chvyrkr]

Not without a tight housing requiring a good gate(s) and variable controller. (Read expensive)

 

[Chvyrkr]

Speaking of, what's your plans for the top turbo? Gates?

 

[Hotrodtractor]

Even at low elevation I don't think you are going to tow heavy with a large single.

I feel like picking on you - mostly because you can take it.

What is a "large single"?

What is towing "heavy"?

Where does "high" and "low" elevation come into play?

At my "lowly" elevation of say 1200 feet (pretty damn low comparatively) I have towed with S400 based chargers on manual trans trucks that exceed the legal limits on a regular basis with 7.3s. Inducers on those S400 chargers ranged from 65mm to 76mm.

I'm picking on you a bit because some of what goes into sizing a turbo setup so its not so laggy and smokey is beyond just the turbo - you also have to look at how its implemented and used. For instance - you say a turbo is smokey and laggy at your elevation - a bump in a couple of hundred RPMs from a gear change or a transmission tuning change might make it snappy and responsive. This is super easy to do on a manual trans truck - but slightly more complicated on an auto truck - on the manual truck its just changing how its driven and shifted.

Another example - I run 33" tires on my Dmax using 3.73 gears - its pretty responsive across the throttle for the most part - except when its in overdrive - that transmission actually has two overdrives - so I'm changing to 35" tires - I also plan on regearing to say 4.10s or 4.30s to better take advantage of 6th gear and making it SUPER responsive everywhere.

Just some food for thought from a redneck in Ohio.

 

[TARM]

Given what HRT has brought up it might be useful to get some of the basic info of this build out there.

Big Bore,

From what HRT has put up can you fill in the blanks on what you have planned in those areas:

Manual/Auto Trans?

What tire and rim size?

Dif gearing?

What is your general altitude range you drive regularly in?

How heavy you plan to be towing?

 

[Big Bore]

HRT, as I was reading your questions then your comments about towing heavy with the big charger I was already thinking manual. A guy with a 6 speed driven right, and with the right nozzles and tuning could get away with a lot.

In my limited knowledge a 4202 is probably too big for towing heavy anywhere. Like Curtis said, a 38r is getting large up here.

Heavy is a tandem dually gooseneck etc with a backhoe or full load of hay. I did that all the time with the OBS, stock turbo, Stage I's and a 5-speed. If I cant do that anymore the turbo is getting too big. But I would say a minimum to be called heavy is 10K.

High altitude starts coming into play really hard above 6Kft. You really notice on carbureted gas motors, which hardly anyone drives anymore, but those of us who had the pleasure of going from sea level to 10K with a big block and a trailer can tell you all about it. I consider anything 4K and below to be "low" altitude.

Thanks for the confidence, I guess I wont tell you i'm crying into my pillow now. LOL

 

[Austin]

Even with the stock turbo and stock exhaust housing I noticed a massive difference between Topeka and here in Parker (a hair under 6000 ft). When I went up to grand lake, the turbo lag was quite ridiculous for how small that thing is.

 

[Big Bore]

Even with the stock turbo and stock exhaust housing I noticed a massive difference between Topeka and here in Parker (a hair under 6000 ft). When I went up to grand lake, the turbo lag was quite ridiculous for how small that thing is.

I notice a HUGE difference when I go down to 6000. When I was in TX with a small trailer I literally couldn't even tell it was there.

 

[Austin]

Sea level is funny. It sets over boost codes LOL

 

[Big Bore]

Sea level is funny. It sets over boost codes LOL

C Fro needs to update ur shyt bro. LOL

 

[CurtisF]

C Fro needs to update ur shyt bro. LOL

I called Austin yesterday, but he no cally backy. :wtf:






















Just giving you a hard time, Austin :grouphug: