TBI 350 or 383 build for 1994 Blazer

[SethT]

Howdy all. I've been dabbling with the idea of pulling the old LO5 from my 1994 Blazer. This motor has served me very well for 27 years. It has 156k on it. For all 27 years this truck has had no business in the passing lane. now that everything on the road is about 300hp the situation is worse than ever. I've pretty much ruled out an LS swap. I'd like to stick with period correct architecture. Ideally, I even want it to look stock. So, my thoughts for 300-350 gross hp are:

- 4 bolt small block set up for roller cams
- cylinders heads that actually breath WITH HEAT CROSSOVER
-LT1 or LT4 cam?
- preferably stock intake but would do an Edelbrock TBI if necessary
-SPR Performance TBI modification if necessary
-Tuning....no idea who to talk to about this. EBL Flash II looks interesting...I've done some of this work with EFI Live on a Duramax, though I have less spare time these days.

My goal is about 300-350 gross HP revving out to 5500ish

The reason I'm posting this is because I'm wondering if anyone here has set out with similar goals. If yes, which parts did you select, and what was your experience? I'm not trying to build a monster, just more usable power in small block format, with stock underhood appearance, utilization of factory fuel lines, wire harness, and computer.

 

[Cadillacmak]

My goal is about 300-350 gross HP revving out to 5500ish

I have not done this with a TBI, but with good heads and a cam this will get you 300-350hp no problem. Maybe someone else can advise on the TBI part

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[L31MaxExpress]

300-330 gross HP does not even require a different set of heads.

 

[Schurkey]

I've been dabbling with the idea of pulling the old LO5 from my 1994 Blazer... ...I'd like to stick with period correct architecture. Ideally, I even want it to look stock. So, my thoughts for 300-350 gross hp are:

- 4 bolt small block set up for roller cams

No need for a 4-bolt main block. Nice, not at all essential.

- cylinders heads that actually breath WITH heat crossover

That is probably going to earn you a different intake manifold, and THAT is going to require fabrication.

Summit and Edelbrock had aluminum "TBI" heads with upgraded airflow, and proper bolt-patterns. Both have been discontinued.

Enginequest had iron "vortec-style" heads with a heat crossover, and the conventional bolt pattern. Still had some trouble with intake manifolds on the tall intake ports. Again, discontinued.

-LT1 or LT4 cam?

Sure.

- preferably stock intake but would do an Edelbrock TBI if necessary

Not likely with aftermarket heads. TBI manifold will be set-up for the center two bolts being at a goofy angle.

-SPR Performance TBI modification if necessary

No idea.

-Tuning....no idea who to talk to about this.

Yup. That's the tricky part.

My goal is about 300-350 gross HP revving out to 5500ish

The reason I'm posting this is because I'm wondering if anyone here has set out with similar goals.

Heaps of people. Whether they achieved those goals is a whole 'nother question.

 

[PlayingWithTBI]

I'd like to stick with period correct architecture. Ideally, I even want it to look stock.

Good for you to keep the SBC platform Maybe I can help...

- 4 bolt small block set up for roller cams

4 bolt not needed unless you wanna go ~500HP but, the roller cam is definitely the way to go. Your 94 block probably doesn't have the bosses for a roller and, unless you wanna spend big bucks for Link Bar lifters, find one that does.

- cylinders heads that actually breath WITH heat crossover

Unfortunately there's not a lot of TBI heads, with the 4 holes drilled @72° for its manifold. You can go with a spread bore manifold with a good TBI adapter.

-LT1 or LT4 cam?

There's a lot of cams available for these engines, ask your favorite cam company. I ran a Lunati Flat Tappet for a while until it wiped out and my rotating assembly with it. Then I went with a 08-430-8 Comp Cam for a while until I bought a Blue Print "383" with a 08-432-8 Cam. All 3 setups put out 350 up to ~430HP.

- preferably stock intake but would do an Edelbrock TBI if necessary

That's fine but, you'll get a little more torque with the Edelbrock 3704

-SPR Performance TBI modification if necessary

Good choice, maybe a 50mm from a 7.4L too?

-Tuning....no idea who to talk to about this. EBL Flash II looks interesting.

Great platform but, it won't control your 4L60E (or 80) trans so, you'll have to run parallel computers. FYI - RBob (Dynamic EFI) is MIA for the last few weeks. No one has heard from him, unless he's been back recently.

Don't forget about freeing up your exhaust too with headers, a high flow Cat and muffler(s). Tuning is absolutely necessary IMHO. Hope this helps, good luck. As always YMMV

 

[Sean Buick 76]

1. Yes to adding cubic inches with a 383 stroker kit. Have the block bored out, mains align honed, deck milled parallel to the main journals etc. also have the bottom skirt of the block machined or ground to clear the big ends of the rods. Have the deck milled to give zero deck to piston clearance then use a 40 thou gasket for optimal quench distance. Use the piston dish and head chamber size to get the compression ratio you want based on fuel octane you want to run.

2. Ditch the TBI style heads and use AFR enforcers with a regular 4 barrel intake. Use a sheet of 3/8” alum and make a simple adapter plate to adapt to a TBI. Use a 454 TBI and switch to a newer ECU and pay someone to tune it.

3. Use longtube headers and dual 3” pipes.

 

[Cadillacmak]

3. Use longtube headers and dual 3” pipes.

Yes! That's how I set up my 75 F250. You don't kill any horse power that way.

 

[PlayingWithTBI]

Use longtube headers and dual 3” pipes.

It's nice to have but, dual 3" pipes aren't necessary up to ~500HP.

 

[Sean Buick 76]

It's nice to have but, dual 3" pipes aren't necessary up to ~500HP.

But they sound so good lol! Fine 2.5” minimum

 

[Komet]

Don't have a lot of spare time but you want to do a custom engine swap hmm? You should be warned this is a hundreds of hours endeavor.

I think perhaps the most straight forward thing to do based on the criteria of keeping all the stock equipment would be to find a running L31 donor, take the hit and buy the $650 conversion intake manifold, and then swap all your stuff over and see how she does. Stock cam and long tubes would probably put you in the HP ballpark and you won't have to get into pushrod geometry or cam timing at all.