I'm wanting to replace the 180k mile LB9 in my '88 convertible with a healthy 350. I'm looking to eventually make somewhere between 350 and 400HP. Here are my block options:

'87 L98 (stock)

'97 Vortec bare block (2-bolt, no heads, pistons, etc.) casting #10243880

'80 long block (4-bolt) casting #3970010

My question is, which of these two are going to give me the most power for the least amount of machine work, and for a reasonable price. I'd like to start out with the stock TPI setup, eventually move up to a larger intake and runner setup, and maybe, if money allows in the future, end up with DFI, mini-ram, and a supercharger.

This much is known - I will be boring .030 over, adding forged pistons and rods, a decent cam, and headers.

Most important - I need to remain emissions legal, and get relatively good gas mileage (18+ MPG).

Anyone have any suggestions? My initial budget for this motor is somewhere around $1500. But as I mentioned before, I'd like to eventually see a supercharger (with appropriate cam), a mini-ram, and DFI setup. Keep in mind that I'd like to keep as much as possible through the transitions. Thanks ahead of time. - John'89L98

 

Considering your horspower goals, you can probably chose any of them, although i don't know how much stuff interchanges between conventional sbc's and vortec engines, so i'd probably go away from that one. Again, considering the build, machine work won't differ very much. I'd take the L98 block since it has provisions for a roller cam. Seriously, however, i really think $1500 is going to get you very far starting from scratch like this and you still have to put some money into your intake to support that kind of power. For a budget build you'd probably just have the necessary machine work done (.030 over etc etc), toss in some new bearings and rings and the rest of the basic rebuild parts, and have the stock rotating assembly reconditioned. only thing you need is a set of oversized pistons. Keith black hypereutectic pistons would be a good choice for this kind of build; much stronger than the stock cast pieces and fairly cheap. Trust me that LTR intake is not going to put your stock crank or rods in danger of overreving. You should use the L98 heads and have them ported out and have bigger valves installed. However, after all this work you've probably gone through your $1500 already. $2500 would be a little more realistic because you will money in other areas as well. At this point get a moderate roller cam (~260 advertised duration). There are plenty of options availabe in the aftermarket as well as directly through GM (such as the LT4 cam). That covers the main parts of the build. There are other odds and ends you will need to get as well (hardened pushrods, rockers, opening the intake, TUNING, etc etc). This should be a fairly potent combo with TPI on top and you'll retain gas mileage and smog legality. If you have serious plans for supercharging and so fourth you might want to hold off on this build and put the money towards that instead, because more than likely you'll have to start over again anyway.

 

They're all the same, as far as power potential is concerned.

I'd eliminate the 010 from consideration since it has a different rear main seal, different dipstick location, and no provision for the factory rollers, which the L98 block for sure and probably the truck block will have.

The L98 block is probably the cheapest, easiest path to what you're looking for.

$1500 will get you a fair-to-middling short block; no cam, heads, induction, etc. It will not build you anything much better than a good stock replacement. It is unrealistic, unless you re-use the stock crank and rods that came in it and skip various important but often overlooked machine work such as rod bolt replacement.

 

Buy a good Crate 350, it may be cheaper in the long run. Horsepower requires money.

 

I'd suggest going with the 87 L98 block for a few reasons. First of all like the other guys said it already has roller cam provisions which is a big plus. Also it has the 1-piece rear main seal which is a lot less likely to leak on you. Finally, you don't necessarily need a 4 bolt main block to make 400 horsepower. I belive a 2 bolt will hold up to 400 N/A horses without a problem. If you're going to go to a blower setup in the future you may want to consider a 4-bolt truck block with a 1-piece rear main seal. Also go with the forged pistons....I didn't and now I regret it. Your goal is very easy to reach, but plan on spending about double what you're estimating just to be safe.

 

Thanks to everyone for the replies so far. Here's what I've decided. I'm gonna go with the L98 block. But because this is going to be my first rebuild, I've also decided to just keep it N/A and try for a 325 - 350HP combo. Again, I'd like to keep it emissions legal. I'll be using the stock intake, runners, and plenum to start, but will move up to some LTR's and a larger intake later, if all goes well.

I'll still have the block bored. Pistons and rods will be replaced, but I doubt I'll need to go forged. Am I ok with cast, or should I be looking in the hypereutectic direction? I'm hoping I'll be able to reuse the stock crank. Depending what I do in the heads department, I'll probably end up with new valves. Which brings me to...

What kind of heads and cam combo should I be looking for? Am I better off just having the stock heads recondition, or should I go out and look for a decent set of aftermarket heads?

I'll also need advice on header size. I have a set of SLP 1 5/8" headers in the garage, but I need to have a y-pipe made up for it. This should suffice, no?

Remember, this isn't going to be a track car. It is a daily driver that I'd like to get some extra power out of. I'm tired of being out-accelerated by a good number of V6 cars. Thanks again. - John '89 L98

 

If you are looking to make those kinds of numbers at the back wheels, then copy my combination listed in my sig.

Oh yea, and my Vortec block is 4 bolt main, one piece rear main, and hydraulic roller.

Just my $.02

Mike (1bad91Z)

 

Get a good set of aluminum heads and be done with it....

along with a decent cam, you should have no problem getting 400hp

 

Well, I'm back and ready to dive back into this engine rebuild. Forget everything I typed previously... I picked up an L98 long block and after tearing it down, will have it in the shop to get dipped, bored, honed, etc. Here's what I know I'm gonna go with initially:

L98 2-bolt
Vortec heads
Forged pistons
Stock rods and crank
AS&M LTR
SDPC Vortec TPI Intake w/ ext. EGR
Stock plenum (ported)
1 3/4" headers w/ AIR
3" cat
Dynomax cat-back
3.42 gears
Underdrive crank pulley
stock fuel rails
AFPR
Holley C950 DFI

Here's what I'm not sure of yet:
52mm or 58mm throttle body
24lb or 30lb injectors
ZZ3, ZZ4, or other cam

I need to stay emissions legal, and I'd like to get decent gas mileage. If anyone disagrees with any of the "known" items, or has any suggestions on the "not sure of" items, please let me know. Thanks again, and sorry for the long post.

 

I'm also not sure as to whether or not I can retain my emissions related equipment while using DFI. I know it doesn't have provisions for emissions stuff, but I'm wondering if there's a way to integrate the C950 and the stock ECU. Thanks again. - John

 

Anyone?

 

the C950 Replaces the stock ECU, and eliminates emmisions. IF you need emmisions, use the stock ECU and learn to burn Proms.

I have 2 cars now with the Commander 950, its really fun to use, but it cant control some of the important things like lockup, Cruise, Emmisions... but it can do other things that the stock ECU cant.

<b>Daily driver </b> Your going in the right direction, TPI and forced induction can net you over 20 MPG and an easy 400-500 horsepower. just make sure your gears, stall, and powerband are all very reasonable. keep the stall near stock, and if you have overdrive keep the revs as low as possible, then of course the powerband should match the TPI, an XE262 or 270 would probably be ideal with some bigger runners and even work fine with a supercharger later.
if you plan on adding a charger also keep compression down below 10:1. I run 7 PSI non intercooled on my 9.5:1 383 without a hint of detonation, so i know with an intercooled setup you could get away with at least 12PSI some are doing it here on the board (willie) and getting excellent fuel economy. the commander 950 would make your fuel economy better IMO because of the real time tuning abilities, and you can even run it open loop during cruise to run leaner.... somthing im experimenting with now and getting excellent results.

 

You say your going with the Vortec heads, that limits your options as stock SBC stuff (Acell DFI) is not going to bolt right up to it.

 

400 ponies? 18+mpg = I wish I had that kida gas mileage!!
Im at 400 and I only get about 10-12 mpg

 

thats because you have a carb

 

hey you have a similar setup to me... and that is about exactly the mileage i see.

 

How will having Vortec heads limit my ability to use DFI?!? Isn't it just an engine management system? There should be no connection issues based on which heads I use... Right? - John '89 L98

 

the intake ports on the vortechs are different. so the intake manifold wont work. unless your getting a management system to use on tbi tpi or what not where a vortech intake manifold is available. i dont know much about the different aftermarket management systems tho. but thats basically the low down on that.

 

um, did you look at his parts list? he's getting the SDPC vortec tpi manifold, how would that make the DFI not work?

 

Anybody have any suggestions as to which throttle body, injectors, or cam I should be using? My thoughts are as follows:

52mm or 58mm throttle body
24lb or 30lb injectors
ZZ3, ZZ4, or other cam

Everyone's opinions are welcome. Thanks again. - John '89 L98

 

ask RB, but i think that the zz3 and zz4 cams are the same, and if your getting your specs for those off of DD2000, the program is wrong, at least that is what i heard...

the zz4 is a good cam, but i really like the comp Xtreme Energy series...it's all up to you man.