I Need 20-30 more HP!! Help Please
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
Don't do a miniram or lt1 intake then.
Stay with the intake options I posted above for more torque, with the TPI version being the most torque prone. Other options are exhaust (I know but seriously, it makes a big difference) bigger motor, higher flowing heads, a bigger small cam, and you can also do the frisbee/underdrive pulleys/cut air lid mods.
Just don't go too big on the cam as increasing duration decreases low rpm torque for high rpm power. (Fills the cylinder less efficiently at low RPM, better at high RPM.)
Also, I think what you are really digging on is the mountain of torque the TPI makes. It makes a lot starting way down low. It just doesn't hang on that high in the RPM band but that doesn't matter for a stoplight cruiser. Go to something like an LT1 manifold and you start stretching that power out over a broader RPM band, faster overall, perhaps... but you'll lose that feel you really like right now.
Stay with the intake options I posted above for more torque, with the TPI version being the most torque prone. Other options are exhaust (I know but seriously, it makes a big difference) bigger motor, higher flowing heads, a bigger small cam, and you can also do the frisbee/underdrive pulleys/cut air lid mods.
Just don't go too big on the cam as increasing duration decreases low rpm torque for high rpm power. (Fills the cylinder less efficiently at low RPM, better at high RPM.)
Also, I think what you are really digging on is the mountain of torque the TPI makes. It makes a lot starting way down low. It just doesn't hang on that high in the RPM band but that doesn't matter for a stoplight cruiser. Go to something like an LT1 manifold and you start stretching that power out over a broader RPM band, faster overall, perhaps... but you'll lose that feel you really like right now.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
By the time you do heads cam intake etc you could have just put a supercharger on it and probably still make more power.
Burn up the plastic order it and put it on. Then ya got something
Burn up the plastic order it and put it on. Then ya got something
Drifting
Joined: Aug 2004
Posts: 1,430
Likes: 2
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 1,093
Likes: 0
From: Spring City Tn
I have had 5 c6's in the last 4 years including a new c6 z06. I went through a serious financial crisis and decided to go with my true passion, C4's!! I would never own a c5. I may go back to a c6 someday, but to me, the c4 is hands down a better car than a c5......thanks anyway!!
Last edited by tnz5106; May 4, 2010 at 10:51 PM. Reason: text
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
I have had 5 c6's in the last 4 years including a new c6 z06. I went through a serious financial crisis and decided to go with my true passion, C4's!! I would never own a c5. I may go back to a c6 someday, but to me, the c4 is hands down a better car than a c5......thanks anyway!!
why you say c4 is better, i never rode in a c5, it just doesn't appeal to me looks wise, your reasoning may hold more value.
what your opinion of the airfoil? JK
Last edited by slickfx3; May 4, 2010 at 11:21 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
That's like building a one lane super hwy
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
No easy way with the L98 youre going to have to do intake and exhaust mods to free up whats there in the first place. Cam by itself...may help some but you still need the others to realze the true gain. Gotta pay the man 
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
just set aside 20,000 give or take a few thou..... hey at least you'll have something to show for it....
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
What is the cheapest/easiest way to pick up 20-30 hp without changing exhaust!!
-cut open the air filter cover: free 5-10chp
-toss the "frisbee" from the WP pully area: free & 10chp
-install 160deg T-stat & fan switch: ~$10 & 10chp
-cut back spark plug ground electrodes: free & 8chp
Total cost ~$10, total power gain >30chp
Safety Car
Joined: Dec 2008
Posts: 3,588
Likes: 10
From: North New Jersey
I think we are getting a little carried away with our numbers (unless you can prove to me otherwize, looks like you have some experience from your avatar so...). If it was this easy, everyone would have 400hp beasts!
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
I don't have it in front of me, but the corvette black book says the 3:07 gear was an option in '88 available only with the 4+3 and came with louder free flowing mufflers. My car does have a fantastic sound for stock mufflers and it feels like 3:07 gears, but my window sticker does not indicate it has that option. But you are saying all 4+3s had those 2 things anyway? Maybe I misread the book, I will look again.
Can you explain your rational for not touching the exhaust? If so, perhaps someone can suggest a way where you can keep whatever it is you want from the stock exhaust, while freeing up some easy power. The L98 exhaust is not all that great, and you are talking about adding a rather modest/achievable amount of power (20+ hp). Why make it difficult?
Last edited by Aurora40; May 5, 2010 at 08:28 AM.
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 1,093
Likes: 0
From: Spring City Tn
I don't believe any 4+3 equipped C4 had a rear axle gearing option. There was an overdrive gearing option, though. Z51 cars (and maybe others) had a shorter overdrive gear, so the +3 gears were shorter. I believe it was 0.68:1 vs 0.60:1.
Can you explain your rational for not touching the exhaust? If so, perhaps someone can suggest a way where you can keep whatever it is you want from the stock exhaust, while freeing up some easy power. The L98 exhaust is not all that great, and you are talking about adding a rather modest/achievable amount of power (20+ hp). Why make it difficult?
Can you explain your rational for not touching the exhaust? If so, perhaps someone can suggest a way where you can keep whatever it is you want from the stock exhaust, while freeing up some easy power. The L98 exhaust is not all that great, and you are talking about adding a rather modest/achievable amount of power (20+ hp). Why make it difficult?
If I could change the stock manifolds to headers and better flowing cats but keep the cat back I may go with that.
The bottom line is I just wanted to pick up as much torque/power as I could WITHOUT changing the exhaust ie.... intake porting, throttle body, better injectors, remove frisbee, and maybe later on a mild cam even though the results from the cam would be minimal due to the restrictive exhaust.
Everyone has brought up some very good points and suggestions(except for the c5 suggestion) and I really appreciate your help.................
Last edited by tnz5106; May 5, 2010 at 11:35 AM. Reason: text
Thread Starter
Burning Brakes
Joined: Jan 2007
Posts: 1,093
Likes: 0
From: Spring City Tn
The early c4 has alot of nostalgia for me. Plus, knowing Gordon Killebrew and his passion for c4's has inspired me. Most people 40 and under, think the c4 is the least desirable of any vette. But I think that because of what gm did with the early c4 after they became dedicated to build "a world class sports car" is one of the most important era's in corvette history. The difference between a 1985 tuned port and a 1982 crossfire in monumental. They are 2 totally different cars. The difference between a 1996 and 1997 is minamal besides the LS engine....................just my .02
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
I know the exhaust should be the first thing I should change if I want to see any significant difference. The only reason I don't want to touch the exhaust is that I absolutely love it as it is. It has a crisp throaty sound that I really love.
If I could change the stock manifolds to headers and better flowing cats but keep the cat back I may go with that.
The bottom line is I just wanted to pick up as much torque/power as I could WITHOUT changing the exhaust ie.... intake porting, throttle body, better injectors, remove frisbee, and maybe later on a mild cam even though the results from the cam would be minimal due to the restrictive exhaust.
Everyone has brought up some very good points and suggestions(except for the c5 suggestion) and I really appreciate your help.................
If I could change the stock manifolds to headers and better flowing cats but keep the cat back I may go with that.
The bottom line is I just wanted to pick up as much torque/power as I could WITHOUT changing the exhaust ie.... intake porting, throttle body, better injectors, remove frisbee, and maybe later on a mild cam even though the results from the cam would be minimal due to the restrictive exhaust.
Everyone has brought up some very good points and suggestions(except for the c5 suggestion) and I really appreciate your help.................
The stock L98 cat back sucks big time the way it chokes to 2 teenie 2 1/4, if that, right away with kinks to some ****ty muffs.
then I went to Corsa's i flew with those but they were too loud...period.
engine was too built,you may be fine.
Do your self a favor an adapt like what I did a LTx cat back they will improve your flow dramatically , they are 2 3/4 pipes which looks bitchin, and they hang with stock hangers in the rear so the alignment is easy, just get a 3" y pipe and have the muffler shop fab it to the stock center pipe, and you get get the LTx cat backs for free nobody wants them...
there's your 20 hp and the sound will still be "factory"
Last edited by slickfx3; May 5, 2010 at 11:59 AM.