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L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

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Old 07-06-2006, 07:54 PM   #1
vettefest
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Default Best performance upgrades for 1987 L98

I have a 1987 coupe. My engine is starting to tick the lifters need replacing. Since I'm going to have top half apart. I want to install some upgrades.

My 1987 is stock. I want to add 100-150HP to the flywheel with only bolt ons and no spray. The botom half of the engine is in good shape. The head gasket was replaced 1 year ago. My budget is $2500. First let me know if this is possible with stock TPI. Please advise on parts, specs and how much HP increase I can expect.

Thank you.

P.S. I'm looking for a reliable mechanic in the Chicago area.
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Old 07-06-2006, 08:05 PM   #2
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read my website, form a plan
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Old 07-06-2006, 11:32 PM   #3
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read my website, form a plan
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Old 07-06-2006, 11:33 PM   #4
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$2500...

used superram, $700
camshaft, $300
used D-Port heads, $700
headers, $600

the misc crap like gaskets and bolts may add up to just a little more than the $2500 goal, plus you'd need programming.
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Old 07-06-2006, 11:53 PM   #5
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Are you sure that's not the injectors ticking?

Put your hand on the fuel pressure regulator, does it match the sound?

Plans are good, which is why I still havent' cracked the motor yet. I don't want to bother doing, say, a camshaft, without doing heads.

One thing that will be of immediate benefit, is a better intake. I'm working on a ported TPI with bigmouth base. I figure if that nets a modest 8% more horsepower, that same 8% will be a bigger gain as I do other mods later, generally speaking.
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Old 07-07-2006, 04:07 PM   #6
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It's more of a tapping sound and it's also burning oil. Blue smoke comes out of the exhaust when it's first started. More blue smoke appears if you rev the engine.

I NEED YOUR HELP THANK YOU
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Old 07-07-2006, 04:20 PM   #7
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need to do a leak-down test
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Old 07-07-2006, 05:19 PM   #8
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Forgive my ignorance. What is a leak down test?
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Old 07-07-2006, 06:49 PM   #9
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Quote:
Originally Posted by vettefest
I have a 1987 coupe. I want to add 100-150HP to the flywheel with only bolt ons and no spray.
Only bolt-ons? I suppose that would depend on your definition of "bolt-ons".

Are heads bolt ons?
Is a cam a bolt on?

I say "no, they are not", which means "no, you can't get 100-150hp with only bolt ons."

Real, true, genuine power gains will run about $50 per hp. This means your $2500 will net you about 50hp....and if it is all spent on true bolt-ons, then 50hp is being generous.


PS. A leak down test: putting air pressure in a cylinder and measuring how long it takes to lose pressure. This will tell you the condition of the head gasket, rings, and valves. (also the condition of the piston, if you're really unlucky!!)

Larry
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Last edited by rocco16; 07-07-2006 at 06:52 PM.
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Old 07-07-2006, 07:41 PM   #10
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For a little more clarification: from www.powerhouseproducts.com

Dual Gauge Leakdown Tester
PART #POW301018
$119.95
See website for pic.

DESCRIPTION:
Racers prefer the dual gauge design of our Leakdown Tester to check for problems with piston rings, valves, head gaskets, etc. The left hand gauge shows incoming air pressure, while the right hand gauge (once plugged into the cylinder being checked) shows how much air the cylinder is holding. The difference between the two gauges is your leakdown. A universal 14mm spark plug adapter, rubber gauge protectors, high-quality regulator and complete instructions are all standard with our precision Leakdown Tester.

If air is leaking, you have a problem (although all engines will leak a little). If it's coming out the exhaust, you have bad exhaust valves, same for intake vlv's if it's coming out the intake! If it's coming out the valve cover / pvc valve hole, you either have bad rings or valve guides / seals. If it comes out the radiator / coolant overflow tank, you've got a blown head gasket. The old compression test without and with a squirt or two of oil in the cylinder trick will tell you if it's ring's, or guides. If you do a dry comp. test and it's low (less than 120 or so psi), put a squirt of oil in the cylinder and do it again. If it comes up, the rings are bad (the oil runs into the grooves and seals them), if it doesn't change, it's the valves / guides / seals, because the oil doesn't get to them due to their location above the piston. Hope this helps. Most of this you can test with a $30.00 (approx.) compression checker from Sears (I say their's because I know it's a two piece design with a air chuck style conection inbetween the hose and the gauge, any one of this construction will work) and a source of compressed air (Compressor, air bottle, etc....as long as it has a hose with a female air chuck on it). The only thing this won't tell you is the actual percent of leak down, but with these symptoms, we already know you have a problem! Hope this makes it clearer for you, a leak down test is the right way to do it, but other than us serious racers, not very many people have the tool to do one. You need to find out what exactly is wrong before going any further, because you might be going pretty seriously into this motor, I'm guessing the heads at a minimum. Then you might want to consider a set of aftermarket heads with you're $2500.00 budget (or rebuilt and ported stockers, but by the time you're done, you'll be close to what the aftermarket heads would of cost you anyway. Also, the ported stockers won't flow too much better than the box stock aftermarket heads, which wouldn't leave you with any options if you decide you want to go even faster later on.) and then do some other upgrades to support them as you can afford it. This would also put you on track for your 100 to 150 hp gain, but a lot more will be needed to get there (Cam, intake, headers, exhaust, new chip, etc...). By theirselves, even the aftermarket heads aren't going to do you much good, because your stock intake and exhaust system are going to be chocking off the flow potential of the heads, but if you really want to do this, and your going to keep the car for a while, and your heads turn out to be needing an overhaul, now will be the time to do it. Or, if you want a smaller power gain but now, I'd recommend a stock rebuild on the heads (assumingb the heads are the problem, of course), a set of new factory lifters (to cure the ticking), air box lid mod, high flow filter, and a set of headers & exhaust system, with req. computer tuning to support (Basically all the standard begining performance upgrades). Hope this helps clairify things.

Last edited by Blownfuel1; 07-07-2006 at 08:01 PM.
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Old 07-07-2006, 08:39 PM   #11
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Quote:
Originally Posted by vettefest
I have a 1987 coupe. My engine is starting to tick the lifters need replacing. Since I'm going to have top half apart. I want to install some upgrades.

My 1987 is stock. I want to add 100-150HP to the flywheel with only bolt ons and no spray. The botom half of the engine is in good shape. The head gasket was replaced 1 year ago. My budget is $2500. First let me know if this is possible with stock TPI. Please advise on parts, specs and how much HP increase I can expect.

Thank you.

P.S. I'm looking for a reliable mechanic in the Chicago area.

for $2500, i dont think its possible, thats my opinion. my heads costs me $1235 US, and exhaust is pricey.
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Old 07-07-2006, 08:50 PM   #12
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Quote:
Originally Posted by 88BlackZ-51
for $2500, i dont think its possible, thats my opinion. my heads costs me $1235 US, and exhaust is pricey.
I spent over $1000 on heads, $800 exhaust $800, intake, $85 timing chain, $85 used cam, + injectors + gaskets + fluids + hoses + sealers + 2 chips $400 + plugs + wires +valve covers+ $$$ odds and ends. It goes on and on and on.
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Old 07-07-2006, 09:13 PM   #13
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All of my upgrades added up to less than $3000.
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Old 07-07-2006, 09:19 PM   #14
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Quote:
Originally Posted by scorp508
All of my upgrades added up to less than $3000.
About $6000 for the complete engine. $500 for the torque converter, $150 for the shift kit. $500 for headers, few hundred for exhaust, Few hundred for misc "what if's", fluids, etc.

If you did it all for 3k you got damn lucky, or it's a time bomb.

btw, I LOVE that color. that is a sexy corvette!

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Old 07-07-2006, 09:22 PM   #15
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shop around, you can do it. I bought a supercharger for less than that, headers coated for 200, 3" dual exhaust 100, flowmasters 50, etc...just be patient and shop for it. Its really suprising what you can do.
There is a guy selling a 90, stroked with exhaust and 6 spd for 5000 right here on the forum, all my parts and my starter car were bought on the forum. I say you can do it and have enough left over for a tank of gas...
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Old 07-07-2006, 09:36 PM   #16
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Quote:
Originally Posted by scorp508
All of my upgrades added up to less than $3000.
Mine cost so much $$ because Scorp snagged on all the good deals . None left for me.
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Old 07-07-2006, 11:19 PM   #17
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You can do it for that amount, it'll be tough and you may not get everything exactly the way you want, but it can be done.

Scorp did all of his own work too, which you will need to do if you want that much under this budget.
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Old 07-07-2006, 11:20 PM   #18
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Quote:
Originally Posted by anesthes
If you did it all for 3k you got damn lucky, or it's a time bomb.
I collected the parts over 2 years. When a deal came up, I jumped on it.

Quote:
btw, I LOVE that color. that is a sexy corvette!
Thanks!
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Old 07-07-2006, 11:21 PM   #19
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Quote:
Originally Posted by Spankyellow
Mine cost so much $$ because Scorp snagged on all the good deals . None left for me.
I'll cut ya' a deal on halfshafts. I've still got like 5 aluminum ones in addition to the steel ones on the car.
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Old 07-07-2006, 11:23 PM   #20
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Just curious, why are so opposed to nitrous? There is nothing in your price range that can compete with the bottle.
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Old 07-07-2006, 11:23 PM
 
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