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Engine Build Suggestions

scoutcamper

scoutcamper

Registered Member
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Joined
Jul 17, 2017
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Location
Chico, CA
Hey All,

I am getting ready to head to SEMA this year for work and one of the things on my radar is an engine build for my personal rig.

I have a 1990 GMC Jimmy with the 5.7L TBI and a 700R4 with an NP241. It is sitting on 33's and I believe it has 3.73 gears, but I need to verify that. The horsepower from this motor is incredibly disappointing, my miata had similar power to this truck. I want more power!

Requirements:
Reliability-this is my daily, plus I am a member of the local Search and Rescue team, and regularly use my truck for off road searches, so it has to be reliable.
Power: Looking for 300-ish HP at the flywheel. I want the truck to be fast-ish.
Towing: I will tow occasionally with this truck, up to 4000lbs on steep inclines, currently end up doing about 30mph up the hill and truck gets hot.
CA SMOG Legal: If I didn't have to be smog legal I would throw the motor in the trash and buy an LSx. This means it needs to "look" original, EGR has to function, cat has to be CA Approved, Timing needs to be close to stock, and it has to pass a tailpipe sniff test(can probably make a custom tune for smog if necessary).


Budget: Hoping to be in the $3500 range for this build, planning on putting an additional $1000 into the transmission to get it built, already have a local shop that has done 2 700r4's for me in the past, does awesome work.

Current thoughts:
Pull the motor and have the bottom end done, new crank, new Hypereutectic pistons rods etc. The motor has 160K Miles on it today. Figuring about $1000 for the rebuild of the bottom end.
New Heads, currently looking at Summit 62cc heads, SUM-162108.(these heads are CARB approved!)
New Cam: No clue which one yet, but know I will need it. Can go roller, not sure if its worth it with my relatively limited budget.(CARB Approved would be nice, but not necessary as long as timing/tune will let it pass smog)
Do the "Ultimate TBI Mods"
I am OK with having to run 91 pump gas from here on out if necessary.
Will have a local exhaust shot build me a good free flowing system, figuring about $500 for that work.

That leaves me about $1000 uncommitted, where would that $$ be best spent?

I have already installed a EP241 Fuel Pump, so I have all the fuel I could ever need.

I have everything necessary to do my own tuning(tuned TPI recently) but I will probably have a pro do the first tune.

I welcome any input, questions, concerns, etc! I could use all the help I can get!

20423875_1612980198726555_2539113527343605565_o.jpg
 
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brut4s said:
Smog legal right here. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiAxoOSk5rXAhUG7iYKHWbpB_gQFggmMAA&url=http://tildenmotorsports.com/tilden-motorsports-ready-to-run-engine-package-5-3l.html&usg=AOvVaw3iQ2YXFTgaH7SWJlShrAWz
Click to expand...
The problem with the LS swap isnt the motor or trans that you need, its maintaining the fuel tank evap system for smog from the year vehicle the motor is from(meaning plastic fuel tank swap), on our old trucks that involves a lot of pain...
 
Man, CA is a pain. If you have to stay with that engine, you will want to put your money into quality machine work and good heads. The connecting rods do not need to be changed unless there is a problem. They should be sized, and new rod bolts. They don't make any power. In your budget, according to your numbers, you could upgrade the cylinder head by going with AFR 0919. https://www.summitracing.com/parts/afr-0919. They have the ok with smog police and AFR heads are real nice. The best out of the box head I've ever seen
 
scoutcamper said:
Hey All,

I am getting ready to head to SEMA this year for work and one of the things on my radar is an engine build for my personal rig.

I have a 1990 GMC Jimmy with the 5.7L TBI and a 700R4 with an NP241. It is sitting on 33's and I believe it has 3.73 gears, but I need to verify that. The horsepower from this motor is incredibly disappointing, my miata had similar power to this truck. I want more power!

Requirements:
Reliability-this is my daily, plus I am a member of the local Search and Rescue team, and regularly use my truck for off road searches, so it has to be reliable.
Power: Looking for 300-ish HP at the flywheel. I want the truck to be fast-ish.
Towing: I will tow occasionally with this truck, up to 4000lbs on steep inclines, currently end up doing about 30mph up the hill and truck gets hot.
CA SMOG Legal: If I didn't have to be smog legal I would throw the motor in the trash and buy an LSx. This means it needs to "look" original, EGR has to function, cat has to be CA Approved, Timing needs to be close to stock, and it has to pass a tailpipe sniff test(can probably make a custom tune for smog if necessary).


Budget: Hoping to be in the $3500 range for this build, planning on putting an additional $1000 into the transmission to get it built, already have a local shop that has done 2 700r4's for me in the past, does awesome work.

Current thoughts:
Pull the motor and have the bottom end done, new crank, new Hypereutectic pistons rods etc. The motor has 160K Miles on it today. Figuring about $1000 for the rebuild of the bottom end.
New Heads, currently looking at Summit 62cc heads, SUM-162108.(these heads are CARB approved!)
New Cam: No clue which one yet, but know I will need it. Can go roller, not sure if its worth it with my relatively limited budget.(CARB Approved would be nice, but not necessary as long as timing/tune will let it pass smog)
Do the "Ultimate TBI Mods"
I am OK with having to run 91 pump gas from here on out if necessary.
Will have a local exhaust shot build me a good free flowing system, figuring about $500 for that work.

That leaves me about $1000 uncommitted, where would that $$ be best spent?

I have already installed a EP241 Fuel Pump, so I have all the fuel I could ever need.

I have everything necessary to do my own tuning(tuned TPI recently) but I will probably have a pro do the first tune.

I welcome any input, questions, concerns, etc! I could use all the help I can get!

View attachment 249339
Click to expand...


I would spend a little extra and get a stroker crank for it, the extra 33 cubes will help with torque and will work well with your cylinder heads. Definitely spend the money and get a roller cam, it isn't that much more since your block can be easily modified to accept stock lifters and thrust plate. Just not having to deal with a cam going flat is worth the additional money, but you will make a little more power with a roller. The GM Performance 14097395 should work well in your application and is compatible with stock valve train and is only a little bigger than a stock vortec cam.10185071 is a little bigger cam and is the biggest you can go and still have it pass emissions. Make sure you use a melonized distributor gear. I highly recommend you get a larger throttle body (50mm from ebay works) and you will definitely need some PROM tuning to make it run well.
 
If you want smog legal you may be in a bind. You're technically not allowed to change any of that stuff on the engine like cam or anything else unless it's carb approved. The smog station likely won't be able to tell what cam is in there, but you've got to have all the stock manifolds, smog pump, EGR and all that junk on there in order to pass the visual inspection. The sniffer test is the easy one.
 
My suggestion, is to pick your heads first. Build the rest of the motor around the heads.

If aluminum heads your compression ratio needs to be 9.5-10, with iron heads 8.5-9. You can go higher than this, but without special attention to quench it'll detonate. The exact cr needs to be set by the cam you choose. Too low compression with too big of a cam makes it lazy down low. Too much compression with too little cam and it'll rattle like a paint can.

Need to pick cam by how much lift the heads will handle, and when they stop increasing flow. If the heads won't flow any more at .500 lift than they do at .450 then there is no use spending the money on better valve train.

If you get good flowing heads, but don't have enough lift with the cam, you can get higher ratio rockers, but you need to plan for this as you may need to open up the pushrod holes before installing the heads.




Now for 300+ hp, I would rebuild at 9.0 cr, a set of good worked over vortec heads, cam around 280 advertised duration with a 112-114 lsa, performer tbi intake, and a tune.
 
I just got done with putting together a 350 TBI engine. I bought a new GM Goodwrench TBI 350 crate engine with 9:1 Compression. Then I removed the stock cam, and put in a mild Comp Cam PN# 12-304-4. I sent my TBI to a guy named Vic Morse, who bored and rebuilt my TBI to flow more air. I also put a fuel pressure regulator on it, and a set of flow matched injectors. I had the stock aluminum intake bored out to match the bore of the TBI. also, I put a set of AC/Delco EP377 fuel pumps into my saddle tanks, which are capable of 33-PSI max. I have set my TBI fuel pressure regulator to 13-PSI. I put a set of mid-length headers on it with a 3" single pipe exhaust system and turbo muffler. I am getting about 265-HP at best out of this combonation (probably less than that). If my engine had more cam it would probably be pushing closer to the 300-HP mark. If my engine had the set of heads you are thinking buying with a bigger cam, then it would probably putting out about 300-HP easy. Any bigger cam than the one I got could involve some custom chip burning and tuning.

full
 
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Can you "swap" to TPI legally in CA on the truck?

My buddy has a 1995 K2500 with the 5.7L, smaller tires, better gears, NV4500, and my L31 with TPI and headers stomps the crap out of it.

TPI alone is worth quite a boost in torque (not so much HP as it's flow limited) and because the LSx motors are all the rage now, the TPI setups have really come down in price.

On any (real) hills though I think you'll be disappointed towing that much weight with any 350. Maybe if you had 4.10's you'd have less issue, and the 700 might help since I'm running the 465, but with an estimated 1500lb trailer, I have no more oomph climbing hills.
 
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