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L98 Experts... advise/help

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Old 10-01-2017, 10:18 AM
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ZEROVETTE7
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Default L98 Experts... advise/help

Just got me a 91 coupe L98, A4 (700R4) with 68k on the meter, I知 planning for a compression test to make sure all is ok inside, as it had some oil leaks. Thinking of give it a new set of gaskets/ seals (refresh/maintain the engine) and since I知 there I知 thinking of throwing some Mods to boost the ride to 300-350 rwhp with bolts on (nothing extreme for now) if possible. the plan is:
  • set of gaskets/seals (any advise on brand or supplier?).
  • Long tube headers (ss/coated/titanium, which brand preferred?)
  • Cat back exhaust system (thinking of Borla 3?)
  • Cold air intake with K&N filters (any specific type/brand?)
  • 1.6 RR (need advise on those if required or not)
  • Rear axle 3.07 (thoughts on that?)
  • Runners??
  • AFPR (is it required?)
  • Torque converter (2400,2600,2800??)
  • Intake manifold upgrade (is this considered a bolt on?) should I go for it with the above?
Am I missing anything? I really need your expert advise on that and feedback. And would like to mention that the whether where I live is hot and humid almost 8 moths in a year (105-120f on average) does this requires any cooling system for oil/trans , stat. ...etc ??

Im considering DIY ;are all the above can be a DIY project or does it require a pro work, I知 not a mechanic in the since but it痴 always my dream to work on corvette and have it as a hobby when retired
I appreciate your feedback and apologized for the long text.
TIA
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Old 10-01-2017, 11:26 AM
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We need to see pics of your new ride!
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Old 10-01-2017, 12:52 PM
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That痴 the one: I値l get photos of the engine once it get cleaned up.



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Old 10-01-2017, 12:57 PM
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Originally Posted by ZEROVETTE7 View Post
The RF wheel belongs on the driver side. Is the driver the opposite of what's mounted now on the RF? RR is correct mount!

Last edited by WVZR-1; 10-01-2017 at 12:58 PM.
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Old 10-01-2017, 01:26 PM
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Originally Posted by WVZR-1 View Post
The RF wheel belongs on the driver side. Is the driver the opposite of what's mounted now on the RF? RR is correct mount!
Yep it痴 actually the LR , will switch em soon
thx👍🏻
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Old 10-01-2017, 01:27 PM
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Any feedback / advise on the OP? Appreciated
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Old 10-01-2017, 02:53 PM
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Originally Posted by ZEROVETTE7 View Post
Just got me a 91 coupe L98, A4 (700R4) with 68k on the meter, I知 planning for a compression test to make sure all is ok inside, as it had some oil leaks. Thinking of give it a new set of gaskets/ seals (refresh/maintain the engine) and since I知 there I知 thinking of throwing some Mods to boost the ride to 300-350 rwhp with bolts on (nothing extreme for now) if possible. the plan is:
  • set of gaskets/seals (any advise on brand or supplier?).
  • Long tube headers (ss/coated/titanium, which brand preferred?)
  • Cat back exhaust system (thinking of Borla 3?)
  • Cold air intake with K&N filters (any specific type/brand?)
  • 1.6 RR (need advise on those if required or not)
  • Rear axle 3.07 (thoughts on that?)
  • Runners??
  • AFPR (is it required?)
  • Torque converter (2400,2600,2800??)
  • Intake manifold upgrade (is this considered a bolt on?) should I go for it with the above?
Am I missing anything? I really need your expert advise on that and feedback. And would like to mention that the whether where I live is hot and humid almost 8 moths in a year (105-120f on average) does this requires any cooling system for oil/trans , stat. ...etc ??

Im considering DIY ;are all the above can be a DIY project or does it require a pro work, I知 not a mechanic in the since but it痴 always my dream to work on corvette and have it as a hobby when retired
I appreciate your feedback and apologized for the long text.
TIA
You are asking for a 50% increase in RWHP.
3" exhaust sure sounds like over kill to me.
Hot cam and kit with lifters springs and rocker or better.
Fresh timing gears and chain.
It already has a cold air kit for the cold air you don't have.
Intake an XT should fit under the hood and no doubt new larger injector.
Someone to tune it properly with the gear from Moats or TunerCat.
Rear gears are always good and just have to decide how much RPM you want to deal with on highways. If you had a ZF 6 SPD I would have said 3.73 gears but with the auto 3.07 is certainly an upgrade. Did you check consol lid to see what the car was built with for gears.

Just a start and advice is free so take it for what it cost you.
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Old 10-01-2017, 11:40 PM
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Originally Posted by ddahlgren View Post
You are asking for a 50% increase in RWHP.
3" exhaust sure sounds like over kill to me.
Hot cam and kit with lifters springs and rocker or better.
Fresh timing gears and chain.
It already has a cold air kit for the cold air you don't have.
Intake an XT should fit under the hood and no doubt new larger injector.
Someone to tune it properly with the gear from Moats or TunerCat.
Rear gears are always good and just have to decide how much RPM you want to deal with on highways. If you had a ZF 6 SPD I would have said 3.73 gears but with the auto 3.07 is certainly an upgrade. Did you check consol lid to see what the car was built with for gears.

Just a start and advice is free so take it for what it cost you.
Thanks ddahlgren,
i have the 2.59 gears.

Will the list above get me to the target? Not looking to drag it (for now) just street drive start stop and keeping the stock look as possible.
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Old 10-03-2017, 12:51 AM
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No L98 experts with mods? Really need the advise TIA
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Old 10-03-2017, 09:30 AM
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Originally Posted by ZEROVETTE7 View Post
Thanks ddahlgren,
i have the 2.59 gears.

Will the list above get me to the target? Not looking to drag it (for now) just street drive start stop and keeping the stock look as possible.
I am rather certain there is decoder or link to one on this site that will translate that list into an options list in English.

My best advice to you is to strat with a budget and an honest estimation of what you can do and what you will need help with paid or otherwise.
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Old 10-04-2017, 07:28 AM
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Originally Posted by ddahlgren View Post
I am rather certain there is decoder or link to one on this site that will translate that list into an options list in English.

My best advice to you is to strat with a budget and an honest estimation of what you can do and what you will need help with paid or otherwise.
thanks for the advice 👍🏻
The plan is to start with refreshing/maintain the engine by replacing the gaskets/seals... valve covers gaskets and probably the valves cover themselves as they are in bad shape (pealing, blistered..), upper intake and runners cleaning/polishing, TB cleaning, changing air filter, probably replacing heads gaskets (if it痴 somthing I can do (does it requires lifting the engine or somthing?), over all cleaning and servicing...

but since I知 there I was thinking of adding some bolts on mods to boost up the performance (list in the original post up)
budget wise $2000-3000. (Will it cover?)

As I mentioned this would be my first time doing such work, im excited to bond with my car.
so I appreciate any advice and help I can get from here...
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Old 10-04-2017, 12:22 PM
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Not an expert but I learned from doing/redoing my car a few times. Agreed the 'cold air' and KN is wasted money, as is multi-spark ignition.

Headers, certainly coated, are a great early step, one you'll want further down that mod road, along with freer breathing mufflers. Mine are the loudish Flowmasters, tail-ending the mandrel bent 3" pipes.

Ensure stock ignition is spot on. HEI is fine for beyond what you plan.

I like the SuperRam's broad power band, though it's a PITA to install. My 409cid is very torquey and the 3.54s are fine, but I might like 3.36 or 3.07s. The ZF's 50% overdrive is superb for highway cruise, with best mpg @ 80-85.

Best approach is to define, NOW, what exactly you want from the engine, tho, I know it's tough to quantiy beyond some number; then stick with ONE knowledgeable builder's formula for intake, cam, injectors, etc.

Tuning is ESSENTIAL or the rest is wasted. Custom preferred, of course.

I battled cooling issues (So.Calif) and feel I wasted $ on the aftermarket pump and radiator. Also, the stock '84 single fan does fine with a higher flow 180 Robert Shaw thermostat, but drilling bypass holes in a Stant may do just as well. My fan got a lower activation temperature since my initial, minor mods began 20+ years ago.


Did I mention proper tuning?

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Old 10-04-2017, 02:22 PM
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Originally Posted by ZEROVETTE7 View Post
Not looking to drag it (for now) just street drive start stop and keeping the stock look as possible.
What are the highway speed limits (if any) in Dubai? If you'll be doing some high speed driving, you might want to stay with the low numeric rear end gear ratio.

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Old 10-04-2017, 02:34 PM
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Originally Posted by WVZR-1 View Post
The RF wheel belongs on the driver side. Is the driver the opposite of what's mounted now on the RF? RR is correct mount!
Originally Posted by ZEROVETTE7 View Post
Yep it痴 actually the LR , will switch em soon
thx👍🏻
Unfortunately, your tires are directional, and will need to be switched too.

(That makes it three posts from Mission Viejo, California! Hi, Whalepirot!)

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Old 10-04-2017, 07:23 PM
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L98 engines are a slippery slope. Once you get started, there is no end.

BUT.. Since you asked.... First I'd do a compression LEAK down test to determine the condition of the engine. If all is well (should be) There is no need to replace anything that is in good service, such as head gaskets, oil pan gaskets etc. But is is an old car so be my guest and have at it.

You have to get more air in and out of the engine, so I'd opt for a Corsa exhaust and some long tubes. Next I'd try a good intake and runners and possibly a tune. You will not need a throttle body.

Next would be gears something like 3.30's or in that neighborhood.

Of course if you want real power, your going to have to get a cam change and possibly some decent cylinder heads. A hot cam is a very nice cam (I have one in a mild 350 that runs great!) but you will need some valve springs if I am not mistaken. Put in some valve seals while you are at it.

All of this will cost some money, but it is the only way (without nitrous) to make the car a competent street performer.

Only other route is a turbo/supercharger.
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Old 10-04-2017, 11:52 PM
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Originally Posted by Hot Rod Roy View Post
What are the highway speed limits (if any) in Dubai? If you'll be doing some high speed driving, you might want to stay with the low numeric rear end gear ratio.

they are strict here with highway speed limits so no high speed driving..
thx
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Old 10-04-2017, 11:54 PM
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Originally Posted by Hot Rod Roy View Post
Unfortunately, your tires are directional, and will need to be switched too.

(That makes it three posts from Mission Viejo, California! Hi, Whalepirot!)

eventually all will go and new will come
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Old 10-05-2017, 12:05 AM
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Silly me, thinking this was an engine build thread! Tyre wear accelerates with mo motor. A consideration may also be what engine tuning/building resources are available to you there? If limited, as I suspect, simple (no boost) moves up MY list.
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Old 10-05-2017, 12:13 AM
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Thanks Guys

so im going for the compression test first and leak down test to make sure all is ok inside, probably this weekend.

If all checked out, will start with the upgrades (I know once I start I won稚 stop as I said it痴 gonna be a long term relation with the vette.

First:
- long tube headers (suggestions would be appreciated, brand, size..etc) whether SS ones or coated.
- Cat back exhaust system (suggestions?)
anything needs to be done with air intake, tb, ...etc at this stage?

TIA
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Old 10-05-2017, 01:07 AM
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Originally Posted by ZEROVETTE7 View Post
Just got me a 91 coupe L98, A4 (700R4) with 68k on the meter, I知 planning for a compression test to make sure all is ok inside, as it had some oil leaks. Thinking of give it a new set of gaskets/ seals (refresh/maintain the engine) and since I知 there I知 thinking of throwing some Mods to boost the ride to 300-350 rwhp with bolts on (nothing extreme for now) if possible. the plan is:
  • set of gaskets/seals (any advise on brand or supplier?). Fel Pro
  • Long tube headers (ss/coated/titanium, which brand preferred? Melrose ss
  • Cat back exhaust system (thinking of Borla 3?) also Melrose 3" into 2 1/2"
  • Cold air intake with K&N filters (any specific type/brand?) Most any reputable brand
  • 1.6 RR (need advise on those if required or not) Scorpion or Comp Cams
  • Rear axle 3.07 (thoughts on that?) Good choice
  • Runners?? Biggest you can get
  • AFPR (is it required?) yes
  • Torque converter (2400,2600,2800??) 2400 for the street, no racing
  • Intake manifold upgrade (is this considered a bolt on?) should I go for it with the above? Usually if you upgrade the intake the runners will not be a factor, most guys get something without runners.
Am I missing anything? I really need your expert advise on that and feedback. And would like to mention that the whether where I live is hot and humid almost 8 moths in a year (105-120f on average) does this requires any cooling system for oil/trans , stat. ...etc ?? Pull the radiator, clean out the area between the rad and condenser and while the rad is out, get it checked and cleaned out, replace if necessary

Im considering DIY ;are all the above can be a DIY project or does it require a pro work, I知 not a mechanic in the since but it痴 always my dream to work on corvette and have it as a hobby when retired
I appreciate your feedback and apologized for the long text.
TIA
All my answers follow your questions, keep in mind you are starting a snowball type thing as it rolls on it gets bigger and bigger.
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