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500+ lbs TQ from a 383

tiger9297

tiger9297

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I have a '90 K5 that needs and engine. This will be my first rebuild so I'm trying to plan and learn at the same time. I am basically trying to copy an engine that looks like it would meet my needs and this is what I have found http://www.hotrod.com/techarticles/66278/index.html . My truck is a very nice truck that I use to travel in, and tow my 28ft. camper and boat with my family on board. I need something with lots of tq, but very reliable and street friendly. I would like to sort of copy this engine but with a 730 CFM TBI unit from Turbo City, OR a MPFI unit from Howell. Haven't decided yet. Price will be a factor. The cam is also something I'm not sure about, and I thought about using Dart Iron Eagle heads or the Dart Platinum series heads. I am open to any suggestions or input that any of you with experience in engine building can offer a rookie. Thanks for your help.
 
Not to sound like a smart-a$$ or anything :rolleyes: . But why not go BIGBLOCK for those kind of numbers ??
 
The dyno that Hot Rod uses is very loose. Their numbers are usually higher than what a real world dyno would provide. This is still a good engine, but I would stay away from the 282 cam. That is too big for a pulling vehichle. I would go with something in the 260 range if you are pulling a trailer.
 
I have thought about going with a BB but it seems that it would cost alot more. I would still have to buy basically everything I will have to buy for the SB plus additional items.

I wondered if the cam they swapped in was too big but honestly I just didn't know. I'm glad you gave me a range to go with such as 260. I'm assuming that would give a good smooth streetable engine that still produced good power. Thanks for the input.
 
Hey Jim, sorry I have'nt pm'ed ya yet, I've been researching your parts. That engine Hot Rod mag. built would not be exactly what your looking for. The magazines are great for ideas, but there usually building street/strip engines for much lighter vehicles. I'll pm ya tonight.
 
i'm seeing a couple of issues here...

first, K5 + 28' trailer = very unstable at speed. you need more wheelbase than the K5 offers. secondly, the K5 has 1/2 ton axles. assuming that you have not regeared it yet, before dumping an engine in, i would look into doing so. might be a better idea to just swap to a set of 3/4 ton axles. there you not only gain in the gear ratio, but also in rear end strength, which is my third concern. i've broken several 8.5s, my most recent one was in my 91 K1500. it wore bald 30" tires, and i was driving on a semi dry day, when all of a sudden it let go. add in higher gears, and a 28' trailer, you're begging for failure.
 
I think 282 would be just fine with a 383. Remember that the more CID you have, the more cam you need to obtain the same low end torque and vacuum at idle. I would say 282 is too much if it were a 350.
 
Oh, and my 383 makes 450 ft. lbs. and gets better mileage than the 350 that was in it (11-14). Let's see you do that with a big block!
 
Make sure you make a post about the enigine if the 383 is way you go. I love those motors on fuel injection!
 
beater_k20 said:
i'm seeing a couple of issues here...

first, K5 + 28' trailer = very unstable at speed. you need more wheelbase than the K5 offers. secondly, the K5 has 1/2 ton axles. assuming that you have not regeared it yet, before dumping an engine in, i would look into doing so. might be a better idea to just swap to a set of 3/4 ton axles. there you not only gain in the gear ratio, but also in rear end strength, which is my third concern. i've broken several 8.5s, my most recent one was in my 91 K1500. it wore bald 30" tires, and i was driving on a semi dry day, when all of a sudden it let go. add in higher gears, and a 28' trailer, you're begging for failure.
Click to expand...

1. As far as towing a 28ft. camper w/ a K5 I can tell you I have been doing so for years and have had no problem at all. I use weight distribution bars and an anti-sway bar. Also, have trailer breaks. No problems there at all.

I have owned this truck since '92 and have towed campers, boats, tandem axle trailers loaded with logs (which is much heavier than the camper) and haven't broken, damaged, or had any mishap whatsoever with the rear end. I figure if something were going to fail it would have failed by now.

2. I have actually considered going w/ 4.11 gears, but the truck pulls the camper fine now and with a new and stronger engine it seems like the need for lower gears would be even less. Maybe I'm wrong there. If I re-gear don't I also have to re-gear the front?
 
theperfectgarage said:
Hey Jim, sorry I have'nt pm'ed ya yet, I've been researching your parts. That engine Hot Rod mag. built would not be exactly what your looking for. The magazines are great for ideas, but there usually building street/strip engines for much lighter vehicles. I'll pm ya tonight.
Click to expand...

No problem there at all. I'm in no hurry I'm just trying to gather as much info. as I can.
 
tiger9297 said:
2. I have actually considered going w/ 4.11 gears, but the truck pulls the camper fine now and with a new and stronger engine it seems like the need for lower gears would be even less. Maybe I'm wrong there. If I re-gear don't I also have to re-gear the front?
Click to expand...
Unless you don't use 4wd, you would need to re-gear the front axle to match the rear axle.
I assume you've got a 700R4; with loads like you describe, the 4.11's would help keep the tranny alive behind 400+ ft/lbs TQ.
 
I tow my race car with my Blazer on a 24 foot tandem axle trailer with 3:73's (presently). It has trailer brakes. I know that there are better setups (long beds, etc.) but I didn't have any problems. I admit that I towed a 30 ft boat with my buddies Suburban it it was a more comfortable tow even though he was down about 100 horses or so.
 
So if this engine package would not be a good one for my purposes does anyone have or know of where I can find some good 383 "packages"?
 
383's are great engines and 500lbs is very possible. My concern would be wether or not you really want to try this with a TBI manifold? I say this because honestly they suck!

Don't get me wrong, I own a 1990 K5 myself and just dumped a small fortune ino a 355 combo that would easily make 400HP/400ftlb with a carb and Vic JR. But with my TBI on it, I'm hoping for 280-300HP which is still a nice gain.

As for the 383 with a 282 comp, I think thats perfect. You may want to put a slightly looser converter in it though. Gears would also be bonus! Not having to smog it would be Bonus! Converting to a TPI/SuperRam setup would be Bonus!

Good Luck

KM
 
Would this still be true even if the TBI were 730 CFM? The engine in the article has a 750 CFM carb. Will a TBI of basically the same CFM capabilities just not produce as much power as a carb?

Another option is a MPFI system. I think Howell has one for around $1200. I'd love to go with a TPI but the ones I've seen are $2k and up. I'm open to suggestions.
 
Here are the specs on a 383 tuned port engine i built for my last blazer.

350 block bored .030"
Custom ground Comp Cams hydraulic roller cam with:

.480" gross intake lift
.487" gross exhaust lift

Duration @ .050" = 206* intake
Duration @ .050" = 212* exhaust

Lobe Separation = 112*

Valve timing @ .050"
IVO = -5* BTDC
IVC = 31* ABDC
EVO = 42* BBDC
EVC = -10* ATDC

These specs are with the cam installed at 108* intake centerline.

Scat 383 1 piece rear main seal crank SCA 9-350-3750-5700
Scat 4340 I beam rods SCA 2-ICR5700
AFR heads AFR-911 (180cc intake runners)
Roller rockers with standard 1.5:1 ratio

Pistons were a KB134

This was a tuned port induction with a 1050mm throttle body BBK 1536

If you punch these numbers into Desk Top Dyno it comes out with making 509 ft. lbs torque @ 2000 rpm and 360 hp @ 4500 rpm

There is a provision for inputting the head flow rates but i can't find them right now, do a search and i'll bet you can come up with the exact flow rates on that head.

If you're running headers you get a more accurate number from selecting the small tube headers with mufflers in the exhaust menu.
 
getting the TBI to flow those kind of numbers has been done. the intake is the problem. ditch the idea of a TBI compatible intake, and go for a carbed intake with an adapter.
 
beater_k20 said:
getting the TBI to flow those kind of numbers has been done. the intake is the problem. ditch the idea of a TBI compatible intake, and go for a carbed intake with an adapter.
Click to expand...

I was thinking of the 730 CFM TBI from Turbo City with an Edelbrock RPM Air Gap manifold. Does this sound like it would work? Would I still have to have an adapter?
 
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