Thoughts on New Engine ?

[Ironhorse]

Been toying with the idea of either trading off my '91 Burb 4x4 for a newer '96 or '97 Burb with the Vortec motor. Currently not having any problems with my '91 TBI 350, just has fair amount of miles, 180,000 but runs well. Carries good oil pressure, change oil and filter every 3,000. Have had the 700R4 trans rebuilt about 4 months ago, last year put in a re-built 3:73 rear end. Like the RV styled body, just thinking for in the future.

Question: Is there a preferable way to go here, trade the '91 for a '96 or '97 or have a 350 Vortec installed in the '91? Is that even an option? Not very literate with the newer computer aided engines being from the old school carb'd engines. Anyone have an idea of the cost of installing a Vortec 350 in the '91 body? Would have to have it done by a shop, don't have the expertise to do such myself. To much old school, I guess.

Any input/tips from somone who has done similar Vortec swaps is much appreciated.

[Farmer Mike]

Honestly, I'd think you'd be better off getting a newer Burb than trying to upgrade your 91. A crate Vortec 350 will need a Vortec intake and EGR plumbing, although you can purchase these parts as a kit. You'll still need to upgrade the TBI and do some hefty chip tuning. There are people that will tell you that all you need is blah,blah,blah (insert technical jargon here), but the learning curve for tuning these vehicles is great. DIY tuning is the best way to see the gains you expected after you sank all that money into it. It's not like an "old school" project that you can throw hop-up parts into and expect instant gradification. If you're up to it and are looking for a deep project, the rewards are there. There are lots of discussion groups on the Net that discuss Vortec swaps.

[mixednuts]

Hello,

I have the same set up you have. 1991 burb with a 350 tbi, We
put 456:1 gears in it with locker in rear and Limited slip in front. it
has almost 200,000 miles on it. I bought it used about 2 years ago.
Presently doing some body work on it for the rust spots which we have
a lot of in the part of the country (northern Michigan). I have to ask
you or anyone, do you have any idea as to what the horse power rating
of this engine is. I will rebuild one day but it is running real good and
oil pressure is about 35 PSI. I would like higher when I rebuild.

I tried to find a place in this forum to ask the question about the horse power
and was not able to make an original post. Perhaps someone will come on
and tell me where this section is and how to start the post.
Thanks: Mixednuts

[Bob Gervais]

The 350 TBI was rated at 210HP, I forget what the TQ is though.

[mixednuts]

Attn Bob Thanks for the quick come back on the Horse Power rating. I hope
if I rebuild it to try and get it up to about 275 HP ....

Thanks again. Mixednuts

[Bob Gervais]

No problem mixednuts. Here is a link to some info I found. http://users.apex2000.net/whardie/horse.html

210 HP, 300 ft-lb. was the spec for the TBI 350, code K, which as far as I know, is the engine code that was used in the Suburban.

Being a small block Chevy, I would think that 275 HP is very attainable, and for cheap money too. I've been playing around with rebuilding mine, and making a game plan for it. I'd like to have everything bought before I pull the engine, so I'm trying to find out what I can do with it. I haven't been very successful yet, but I haven't put much work into it either. Whatever I do find, I'll post here.

I'm thinking, that since this is a low compression engine (8:1), higher compression pistons, say in the range of 9:1, ought to yield the best HP gain for the buck. I'm going to call some cam manufacturers too, to see what they recommend. My experience has been though, with most cams in a street engine, that they simply move the powerband around in the RPM range. Of course, higher lift will give you some gains as well, but we don't want to go crazy and look like we have a Pro Street engine in the family truck.

[Bob Gervais]

Some more info:

http://4wheeloffroad.com/howto/60118/index3.html

No specs on what to expect for power increase, but at least there's part numbers.

Looks like I was wrong about the compression ratio too:

http://4wheeloffroad.com/howto/60118/index4.html

They're listing it as 9.3:1, which is about as high as I'd go for 87 octane fuel.

Here's another interesting link to Jasper Engines. They have a 383 stroker TBI setup, and a 350 setup. The only real differences I saw between the two was displacement. The cams look the same, and the operating range is definitely within our parameters. That at least gives us some cam numbers to shoot for.
http://www.jasperengines.com/pdf/cla...evy350-gmc.pdf
http://www.jasperengines.com/pdf/cla...evy383-gmc.pdf

Here's some more, descriptive info on the TBI and performance. Looks like Vortec heads, a cam, some TBI flow mods, and a chip are what does the trick.

http://www.cfm-tech.com/gm_tbi_camshaft_heads.htm

[u2slow]

I would consider a relatively stock-built 400ci (for increased torque) rather than trying to tune, chip, and cam the TBI for more horsepower on a lesser displacement.

IMO, torque is more important on a something as heavy as a 6000lb Suburban.

Having driven the newer 350 Vortec Suburban, its not anything to write home about. Again its the torque (predominantly generated from displacement) that gives the 'seat of the pants' feeling of power. IMO, upgrading to the newer body would only be worthwhile if you thirst the kind of torque the Vortec 454 puts out.

[Bob Gervais]

Originally Posted by u2slow

I would consider a relatively stock-built 400ci (for increased torque) rather than trying to tune, chip, and cam the TBI for more horsepower on a lesser displacement.

That would be a good idea, for areas that don't require emissions checks at inspection, or govern what sort of engine swap you can do. In my state (RI), if I swap I need to install an engine of the same year or newer, that was offered in that vehicle.

For these reasons, and the simplicity of the TBI system, I'd choose to either rebuild my present engine, or get one of the Jasper ones.

[u2slow]

That puts the Jasper 383 and a 400 in the same boat. Neither is technically legal, yet anything from a 267 to a 400 in TBI dress will have the same outward appearance

[Bob Gervais]

Originally Posted by u2slow

That puts the Jasper 383 and a 400 in the same boat. Neither is technically legal, yet anything from a 267 to a 400 in TBI dress will have the same outward appearance

Ah, now I get it. I thought you meant to swap over to the 400 with a carb and all that stuff. Makes more sense now!

[dapolice1]

Any pricing on the Jasper 383 and I do not see the 400 Jasper with the centerbolt (non vortec heads).

[mixednuts]

Hello,

I went for the 1991 suburban with 4 wheel drive as that is the last year
that the solid front axle was used. We put in 4.56:1 gears to make it
a real nice trail machine. I will keep the info on engine rebuilding listed
above for future reference.
Thanks
Mixednuts