engine replacement

[Larry's Yellow Rdstr]

My 87 has 104,000 miles and is a little tired but runs very well. I would like to buy a short block and rework the heads and get close to 300 HP. I could rebuild my existing engine or buy an aftermarket short block. I do have smog laws to worry about or I'd look into the "Quick Burn 385" and be done with it. My engine is rated @ 240 HP, so 300 HP would be a BIG improvement.
Suggestions-Comments appreciated.
TIA
Lar

 

[Edmond]

Larry,

This is my plan. I figure it'd work for you since we have the same motors:

Since my motor isn't burning any oil, I'm not going to take it apart. I am going to get:

Heads. I'll either have my stock heads rebuilt or I'll get some Edelbrock heads with 1.6 roller rockers.

I'm going to replace the timing chain cover, oil pan gasket and rocker arm gaskets. I'm having some minor weeping from those areas.

I'm going to port the plenum and intake manifold and get some large tube runners.

Long tube headers, though I don't think they're smog legal in CA.

I'm going to replace the pushrods.

Vortex Ram Air.

Complete tuneup including the replacement of all 8 fuel injectors, fuel filter, fuel pump and water pump. I'll probably get a slightly cooler thermostat.

Those mods should get me 300 HP.

 

[vetteboy86]

A good mild cam alone would probably get you to 300 hp easy. The cams in our cars really suck.

 

[tnovot]

I think you are both being too optimistic about HP gains. IMHO, Edmond's plan, especially with some really good aftermarket heads, could come close but Vetteboy's hope for a 60 HP gain with only a streetable cam is unrealistic.
Terry

 

[Larry's Yellow Rdstr]

I would like to spec the engine wear and go from there. If I can avoid boring .030 I would be happier. A .010 bore job, flat top pistons, a little better cam, roller rockers and decent head work will get me to where I want to be, I think. Also maybe I can avoid the wrath of the smog police.

If I can get the car to run consistently in the mid 13s I will be happy.

 

[Edmond]

I would like to spec the engine wear and go from there. If I can avoid boring .030 I would be happier. A .010 bore job, flat top pistons, a little better cam, roller rockers and decent head work will get me to where I want to be, I think. Also maybe I can avoid the wrath of the smog police.

If I can get the car to run consistently in the mid 13s I will be happy.

If you're going to bore, may as well go .030 over because you'll have more options. They certainly sell more parts and stuff for the .030 bore than they do for the .010 bore because the .030 bore is for the 383 stroker.

The exhaust system on the L98's is terribly restrictive. If you redid the whole exhaust system from headers to exhaust, that would get you 30 HP right there at a minimum. The stock mufflers only flowed through one outlet! Then again, I don't think you can do the headers in CA.

 

[vetteboy86]

Depends what your definition of streetable is. He said he was going to rework the heads, and with the mild cam it would probably get him 60 hp.

 

[Vettefan87]

If I can get the car to run consistently in the mid 13s I will be happy.

Your car should get somewhere near that fairly easily. Have you done all the free mods? Like descreening the maf, bumping up the timing etc etc? My car went 13.8 with what I believe was a fouling out O2 and terible 60 foot times. If you are going to bore it you might as well go .030. The displacement is reached with the stroke more so then the bore. I didn't notice a differnece in performance from .010 to .030, in my vette.

Have your heads ported/polished get a better intake, and a cam and you will be low 13's if not better. I am not sure about CA with headers, because that is VITAL for our cars.

 

[Edmond]

I'm pretty sure the headers would be a no go in CA. They don't allow anything but hippies there!:L

If you bore it .030 and use the stock crank, displacement will be 355 cubic inches.

 

[tnovot]

I would like to spec the engine wear and go from there. If I can avoid boring .030 I would be happier. A .010 bore job, flat top pistons, a little better cam, roller rockers and decent head work will get me to where I want to be, I think. Also maybe I can avoid the wrath of the smog police.

If I can get the car to run consistently in the mid 13s I will be happy.

I agree with others about going .030. You might want to also check prices of new pistons and rings first. Often the .030 over are cheaper than .010 over - maybe because they are more popular and/or more available.
Your block should easily withstand the .030 over without problems - something that can't always be said when going .030 over on a 400 SBC.

 

[tnovot]

Depends what your definition of streetable is. He said he was going to rework the heads, and with the mild cam it would probably get him 60 hp.

Vetteboy -
Streetable means anything that still gives good low to mild range torque and horsepower in order to retain decent driveability characteristics.
My response was directed to your first comment in which you said that a good mild cam ALONE would easily get the L98 to 300 HP.
Terry

 

[vetteboy86]

Yes I agree torque is really more important if you ask me on the street, but good horspepower is a plus too. But like I said if he puts bigger valves in the heads, and goes .030 over with a cam it should be fine.

Also going .010 over might not be the way to go only from that fact that it may not be enough, so they would have to bore it again. Going .030 over the first time usually takes care of any problems.

 

[silverja]

My suggestion is to keep the original motor and do the mods as others have suggested. If you ever plan on selling it, you will find it much easier than with a non-original motor.