Just got my vette a week ago and am not happy that my 95 Impala SS will smoke it. Until I can save up for a Superram and base I am wanting to do the following mods. What kind of HP and Torque can I expect? K&N filter, chip, 106 T-stat, hotter coil, 8mm wires and platinum 4 plugs, airfoil. Also wondering what brand of cold air intake is the best and most popular? Thanks in advance. Still learning the L98.

 

Take comfort.....its an Impala. Bet you feel better driving the vette. And, thats what its all about. :smash:

 

skip the airfoil

w/ the 160* thermostat, you'll want to turn your fans on sooner either with a custom computer chip or a fan switch available through some forum vendors (try MAD, ZIP, etc)

you can cut a large(r) hole in the stock air box

also, there is a large metal disk attached to the water pump pully. supposedly GM put it there to dampen vibrations caused by the ac compressor cycling on and off. remove the belt, and the four bolts holding the "frisbee" on the pully. Use washers on the bolts to to take up the thickness of the removed frisbee.

I agree with all your other descisions, except choice in spark plugs. Regular plugs work just as well, but open up the gap a bit with the new coil and wires.

your next mod should be long tube headers and dual exhaust. what you choose here will depend on local laws and $$. I'm using hedman 1 5/8" headers and a muffler shop bent 3" dual exhaust w/ h-pipe and no cats. I would choose at least 2.5" pipes, but would consider 3" with a superram and cam upgrade. Also, if I were to do it over, I would have saved a little more and gone with the Hooker Supercomp 1 3/4" headers.

 

I doubt that you'll even get 20HP from those mods. Save your money on the chip as it's not really needed at this stage of the game. When you do heads/cam then you can consider the chip. You should install a manual fan switch which will allow you to kick your fans on when you want. That's probably the only useful thing that the chip does given a stock motor. I would also not suggest the SR unless you're going to do some cam and head work along with it. You'd be better off porting the stock stuff if you're not going to change the cam or work the heads. Don't even bother with this stuff until you get an exhaust, less restrictive cats and headers.

Mods add up. :-)

Take care and enjoy your Vette!

Ron

 

Youll get no hp from the airfoil, nor the ignition stuff. (provided your ignition is good now, although cutting back the plugs will free up some nice gains)
The thermostat allows you to bump base timing, which can give some. The chip gives almost none.
You should remove the frisbee on the water pump (its a big round weight that serves no purpose) and that'll free up about 10hp.

If you want HP on the L98, youve got to change out the stock exhaust and do intake mods.
A 91 already has good heads, so those need nothing at this point.
What you should do since you cant afford the SR, is to port the plenum runners and base, port matching all the way and siamesing the runners.
Headers (longtubes) give about 15hp, catback about 10hp.

 

Thanks for the input everyone...and yes I do feel better driving the vette. I forgot to mention that the SS has a few minor mods on it, but a grocery getter shouldn't smoke a vette. After reading your posts, I believe that I am going to just save up the money and buy me some good intake parts. I am not going to worry about porting them when I can just buy better aftermarket parts. Just sneaking all these mods past the wife will be the hard part. She doesn't want it too loud. Maybe she won't notice the speed. :rolleyes:

 

Thanks for the input. Think I will just save up the money and go with the intake and exhaust. Is the Superram worth it? With the base and hi-flow runners, what kind of HP are we talking for that kind of money? There has to be a cheaper way of getting HP. Also is Lingenfelter the only one who sells them?

 

We're talking ~380hp with the SR and the 74219 cam that was designed for it. Scorp has this setup on his 87, with the 88-91 heads, although theyve been worked over some. He also has headers, so subtract some if you dont want headers.

Its worth it. Accel has different vendors, but your best cheap bet is Ebay, all the vendors have nearly the same price.

For now just port the stockers.

 

You should also check out TPIS (bigmouth intake), and ASM (Arizona Speed & Marine - siamesed large-tube runners). I've heard ASM makes the best runners. You might want to look for second hand intake parts - There's nothing mechanical about them, so they don't go "bad". Check out the various camaro forums for parts for sale. Also, you should port your plenum or find one for sale already ported (ebay sometimes has them). But again, you won't get any SERIOUS performance out of these mods unless you do the exhaust side as well (including headers). Then go with a head/cam swap.

Also, and this has been a long time debate, you can gut your MAF sensor (remove the screens and fins). Free mod, a little more airflow when you add the hi-flow intake parts.

As far as your air intake is concerned, just get a dremel, hacksaw, or tin snips and cut out the front of your air filter lid, so that there is just enough on the lip to hold the filter firmly in place. It's free, and with a K&N filter, should flow just as much as any aftermarket air intake kit.

Good luck! :thumbs:

 

I'm pretty sure there was no frisbee on a 91 - so nothing to remove :) A tune-up with new wires is good. A DUI (Davis Engineering) cap & coil will be good. Go to NAPA and get NGK FR-5 plugs. Open the air lid as said & add a K&N. Change the fuel filter. The air foil is potentially valuable on a long straight of a road course - of course we never exceed the limits on regular highways :blueangel: - where you're pulling sometihng over 100 (my opinion - that's why AS&M, TPIS, Holly, BBK, etc build them into their performance units), but not on the street. Less restrictive exhaust will sound better but, as said, unless you do something to the intake, it won't improve performance much on its own. Biggest "feel" improvement is always gears on an otherwise stock Vette. And, I always vote for an improved alignment to make it handle like it should have from the factory (but they set it so it's safe & "predictable" for people used to driving Camrys while doing their makeup & drinking coffee). Plus good tires. L98s can be pretty stout if your mods are carefully thought out and done in coordination. By the way, I don't think your Impala will outrun my L98 :D Have fun, L98s are one of the great bargins in the world today. :flag


[Modified by NavyVet, 9:58 AM 9/25/2003]


[Modified by NavyVet, 9:58 AM 9/25/2003]

 

My '91 had a frisbee. Came out without too much of a fight.

 

I stand corrected - you are right - according to the GM Parts Microfiche, the frisbee ("DAMPENER, CLNT PUMP PUL" ' #10105252) 1988 through 1991. My bad :bb

 

Check out http://www.moreperformance.com as they have a ported plenum to use with the large tube runners (siamesed) and the intake base. Everything will be around $900 and they claim a horsepower increase on a stock engine of about 30 HP. If this is true or not, it has to be seen. I think these items are made by TPIS, but I'm not sure. That, together with the KN filter, cut lid, throttle body coolant bypass, removing the frisbee, better exhaust, cut back spark plug electrodes, should give you a boost in power. The bigger throttle body (52mm or 58mm) should not be considered for a stock engine. The TB airfoil is controversial since some people swear at it while other people swear by it. I don't know if your '91 has pre-cats. If it does and the smog ***** are not too bright in your area, gut them or just replace them with straight pipes. Horsepower takes money. Serious horsepower takes very serious money. With what I mentioned above you can realize some nice horsepower increase. Also, you can be set-up for a future camshaft upgrade. As for headers, beware of too-large pipe diameter. As mentioned in another thread, you can lose some low-end torque and gain high-end torque, but you are not going to be racing all around town, are you? :blueangel: :blueangel: :blueangel:

As for the chip, I installed a Hypertech Thermomaster in my 87 Coupe (auto tranny) and for me it works just fine. It just does not only start you fans earlier (you can do that with a manual switch for about $20) but it modifies your ignition timing and injector pulses. I did notice an increase in performance although I have read in this and other forums that they are worthless. Granted, a custom chip is supposed to be better since it is calibrated to your specific engine mods, but of course, it is more expensive I am told. Anyway, good luck with your mods, I expect to hear that you can smoke your Impala.


[Modified by alfonso gomez, 7:34 PM 9/25/2003]

 

Well, I appreciate all of the input that you have given me. I am going to save up my dough and then go for the mods. I just want over 300 HP...in case someone in a little ricer wants to see what the vette is holding. But they would never do that would they? It will be a slow buildup, but I am not planning on selling the ride....ever, so I will keep you posted as the mods go by.

 

Congrats on your new Vette.

For simple starters try these mods:
-160 deg stat & aux fan switch, 10hp
-toss the "frisbee",(details on my site, see sig. below), 10hp
-cut lid with K&N, 10hp; TPIS cold air, maybe 15hp over stock
-cut-back spark plugs (see my site), 10hp; you might also go with HyperTech coil, cap & rotor and TPIS wires to assure good firing to well over 5k RPM.
-AFPR to add fuel at WOT; don't do a chip change yet.
-bump the base timing till just below knock retard for better throttle response; you may need a scan tool for this trim.

Next do some exhaust work:
-headers, 15hp; or 2 1/2" mandrel bent front Y for about 5hp gain
-hi-flow cat & cat-back, maybe 15-20hp

Heads:
-pocket ported & worked #113s, 25hp

Cam:
-ZZ-9, 30hp

Check out the results of L98 mods on my site for the big picture on what you might expect from your L98 with a little work & $$ spent.

I think you'll find that your modded 12sec. Vette will run with your SS.

 

K&N filter, 3-5
chip, 0 (A chip doesn't make power only an engine in tune)
106 T-stat, 3-5
hotter coil, 3-8
8mm wires 0-1
and platinum 4 plugs, 0
airfoil. 3-5

All combined 5-20 HP/TQ
Also wondering what brand of cold air intake is the best and most popular? This is tricky since you have to answer what risk I am willing to run? Many of the intakes will open towards the elements and are called "racing" because the stock will handle a water puddle, most will not.

Once you get rid of the TPI base restriction, you will be happy. But until then just keep up with the regular maintenance.

 

If your Impalla SS is stock and can smoke your L98 their is some out of tune on your L98. A L98 should run low 14's stock, you may want to look get your car running right before modifying it, if that is the case.


[Modified by dgoodhue, 8:11 AM 9/26/2003]

 

once again, thanks for the input. I am going to go with exhaust work first. Even the wife wants new exhaust because the vette doesn't sound mean enough. I should have a K&N filter here tomorrow. Does cutting the airlid help alot? Does it run the risk of getting water in the filter? Let me know on that one before I cut the lid tomorrow. I am going to go with hi-flow runners and some intake work and then hit the t-stat and stuff. Let me know how to do a tbody bypass on our tb's, it is different from my LT1. Also my SS isn't completely stock. It has a ram-air and a few mods on it. You can see it at http://www.smokinss.com. When you get there go to members profiles and then look under Brad Hennessee. Tell me what you think?

 

its still a vette

 

You might want to consider the Power Effects system for your exhaust as it sounds plenty mean when the adjustable valve is open (in the muffler) and a bit louder than stock when that valve is closed. Changing the volume of your car is a simple matter and allows you to tune the mean-ness to your liking. It's also a good foundation for other mods that you may do in the future. Check out http://www.powereffects.com/ for more details.

Good luck,

Ron