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Old 02-13-2018, 03:11 PM
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jdaugherty
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Looking for the best perforance mods for a 98 70k mile. Only mods I have are blacking intake, and flowmeter axleback so far!! Let me know what you guys think!
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Old 02-13-2018, 03:42 PM
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WOW!! That's a LOADED QUESTION..

What are you performance GOALS??

What exactly do you expect from the mods that you install? 10HP, 20, HP, 50 HP............


98, 70,000 mile WHAT? MN6, A4 Automatic, What differential gear ratio is installed, what suspension do you have "FE1 Base, F-45, Z-51" etc.....

The mod differences between a MN6 and an A4 is major and needs to be considered.

Will you be doing a Mail Order Tune or a full on in the Shop Dyno Tune or not tuning at all????

How much CASH do you plan on spending or have on tap????

A LOT goes into satisfying a HP/Tq itch!!

Let us know some more info and we will be very happy to help you spend MONEY!!

Its a SICKNESS,,,,
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Old 02-13-2018, 03:53 PM
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I see I left a few things out I thought I put in there oops lol!!! So 98 70k miles z-51 package a4 trans. Factory gears (sorry not sure what they are). Looking to keep price around $2000-$2500. Hp not really sure I k ow it wont be crazy with that budget. But looking for a nice deeper throatier sound. And a little more power dont need to be crazy just spmthing a little more than stock maybe 450-500 hp range is that's obtainable in my price range!
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Old 02-13-2018, 04:27 PM
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Originally Posted by jdaugherty View Post
I see I left a few things out I thought I put in there oops lol!!! So 98 70k miles z-51 package a4 trans. Factory gears (sorry not sure what they are). Looking to keep price around $2000-$2500. Hp not really sure I k ow it wont be crazy with that budget. But looking for a nice deeper throatier sound. And a little more power dont need to be crazy just spmthing a little more than stock maybe 450-500 hp range is that's obtainable in my price range!
LMAO ROTF!

Brother,, I am NOT laughing at you but at the OUT COME.

Your STOCK HP at the wheel is around 290-315 RWHP on a good day.

The A4 is usually connected to the trans with a 2:73 Ratio Diff, If you are lucky, it may have been blessed with a 3:15 Ratio. Installing a more performance differential gear ratio (say 3:90 Gears) will get you a little quicker car without too much fuss.

( https://www.corvetteforum.com/forums...xle-ratio.html )

The 2:73 gears really hinder that SPORTY acceleration feel.



I have a TRUE 450 RWHP 02 ZO6 that I modded. To get there it takes:

Heads, CAM, Headers, better intake manifold, injectors and a full on DYNO TUNE ($450-$500)

With that cash outlay, I can see you in the 340-360 RWHP range if you spend it correctly.

Getting some good used GM C5 performance parts like a 2001+ intake manifold will put you on the correct path.

Then you need some headers. Purchase the some off shore clone headers for a less expensive performance increase.

You are NOT getting over 400 RWHP with out a head/cam swap.

There is LOTs of potential in the LS block. You just have to get more AIR and FUEL into it with the correct compression ratio to make gobs of HP. The GM OEM LS1 engine just doesn't give it up with out MORE MONEY!

CHEEP,,, FAST,,, RELIABLE

PICK TWO, because you can NOT HAVE ALL THREE!

The more HP you add, will start showing you the WEAKNESSES in the other GM C5 Drivetrain components.
Once you get at or above the 400 HP mark, your transmission may not be happy and I am POSITIVE that your torque tube couplers will start to complain.

Bill

Last edited by Bill Curlee; 02-13-2018 at 05:21 PM. Reason: Correct the A4 gear ratio.
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Old 02-13-2018, 04:42 PM
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"just something a little more than stock" .... "like 450-500hp", haha. Adding 100-150hp doesn't come cheap or easy. $2500 will not go very far, and certainly won't get you 450-500hp.

A set of Kooks/ARH long tube headers and xpipe will set you back roughly $2000. You'll have to do the install yourself (labor will blow the budget). Plus $3-500 for tuning (which is where a lot of the gains come from). should net you roughly 30rwhp? (others might be able to give more specific detail on the hp gain).

Adding a cam is another good option, but again can get very expensive when you tack on the "might as well" items considering age and mileage. (timing chain, oil pump, valve springs, push rods).

**Bill beat me too it; don't mean to pile on. He explained it well. It's an expensive game to play. I vote keep it stock and invest the money in some index funds.

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Old 02-13-2018, 04:53 PM
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To determine your factory gearing you can look under the car for a tag on the differential that will indicate the ratio (either 2.73 or 3.15 for an auto), or you can look at your RPO code listing on the glove compartment door of your car. If you have the 3.15 Performance Ratio, you will have codes G90 and or G92, and probably both. These two codes indicate the 3.15 ratio.
Realize too, that parasitic losses are greater with an auto transmission than with a manual, so all things being equal, you'll make at least 3-5% less horsepower than a manual transmission car.
With the budget you have you cannot achieve 450-500 horsepower. You can, though, get a car that performs better and sounds better. You indicated one of your goals was a nice, throatier sound. You can get that with just the headers Bill mentioned and a nice exhaust system. You'll often see used headers and exhausts for sale in the C5 FS section of the forum. After that, again as Bill suggested, look to a better intake, and then a better.......................
Face it. You're on a slippery hill when you start modding your car. As I used to have on a car I raced in the 70s - Horsepower: Some is good, more is better and too much is just enough!
Best wishes with your efforts.
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Old 02-13-2018, 05:13 PM
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Just gaining 30-35 HP will make you very a happy guy. Better intake and some headers will make the fun factor happen BUT, you will very soon want MORE HP.

I started off with a stock 2002 ZO6 and thought I was king of the hill... Soon you find the limitations of 360 RWHP and I invested in a VARARAM Cold Air Intake, Ported Throttle body and a set of Long Tube heads and a full on dyno tune. Netted 395 RWHP and 375 Tq!! Then I got beat by a damn WRX.

I'll fix that!!!:smash: Ported heads, big cam, FAST 90 intake manifold bigger injectors, full 3" exhaust system AND ANOTHER FULL DYNO TUNE!. Dynoed at 450 RWHP 440 Tq. Cost a LOT but that WRX ISNT any longer an issue!!

Most A4 guys will tell you that you should do a gear ratio up-grade FIRST. Im a MN6/MN12 driver so, I cant really expand on the mod too much other than saying Ive see the A4 cars gain a LOT of off the line quickness with proper gearing!!

Like I stated, its a SICKNESS.

Last edited by Bill Curlee; 02-13-2018 at 05:14 PM.
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Old 02-13-2018, 05:19 PM
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WOPPS!! Forgot to add, the stock OEM ZO6 CLUTCH was NOT HAPPY with the second set of mods and HP over 400. The clutch stuck to the floor requiring a complete clutch replacement.

The STOCK A4 trans is happy serving you on stock OEM HP. When you add higher stall speed converters and higher HP it will very soon smoke its self.

When you add a moderate cam to a C5 with an Auto Trans, you will need to increase the stall speed in the converter. That generates HEAT and the auto trans DO NOT LIKE HEAT! Most guys that have A-4s have to add a better heat exchanger and up-grade the trans internal software (clutches and sunshell hardware.

Last edited by Bill Curlee; 02-13-2018 at 05:25 PM.
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Old 02-13-2018, 05:52 PM
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Originally Posted by Bill Curlee View Post
WOPPS!! Forgot to add, the stock OEM ZO6 CLUTCH was NOT HAPPY with the second set of mods and HP over 400. The clutch stuck to the floor requiring a complete clutch replacement.

The STOCK A4 trans is happy serving you on stock OEM HP. When you add higher stall speed converters and higher HP it will very soon smoke its self.

When you add a moderate cam to a C5 with an Auto Trans, you will need to increase the stall speed in the converter. That generates HEAT and the auto trans DO NOT LIKE HEAT! Most guys that have A-4s have to add a better heat exchanger and up-grade the trans internal software (clutches and sunshell hardware.

Bill is correct. In the never ending circle of horsepower increases (he's right - it's a madness ), you install a more performance oriented cam. It increases your horsepower but also moves the horsepower curve higher. To take advantage of the new horsepower range, you add a torque converter with higher stall speeds, but that acts like the clutch bands are slipping so heat increases in the transmission. As suggested, you add a better heat exchanger (trans cooler). For me, at least, that is the fix. When I changed to my 3600 Circle D converter, I also added the large B&M cooler (don't remember the part number, but it's the large one with the added cooling fan). With the cooler in place, the trans temp has stayed as low (and sometimes lower) than before the torque converter swap. You can also add larger transmission fluid pans with the idea being that more fluid will help keep the temps lower.
Good luck!
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Old 02-13-2018, 09:16 PM
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I think the key message here is the importance of stepping back and looking at the project holistically. There will be more to it than just the hp aspect, as others have mentioned the transmission, etc. So before you buy anything, think through the options, do some research, figure out what works best for your goals and budget, and map out a plan.

I bought my car with a small cam and long tubes. Had zero plans to add more HP... and then the #7 piston cracked (HPDE event)... and if you're gonna build an engine, you might as well add hp. It will be great when it's done, but it's a project I got forced into rather than by choice. There's a lot to be said for keeping it simple (ie, mostly stock) and just enjoying the car. (geez, I sound like an old fart)

Best of luck, and keep asking questions.
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Old 02-13-2018, 09:23 PM
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Thanks for all the replys o guess what I'm really lookong for is thw nice deep throaty sound! I love the way a cam sounds. I also dont race and have no intentions on doing so. So not looking to go crazy. I guess my 450-500 was far fetched so lets forget the hp gains, and get to what I'm really tryong to achieve. Witch is a deeper sound a little more throaty, and a cam but nothing to crazy just really want to hear it if that makes sense. Still learning so Don't really know what I'm talking about 100 peecent yet so just bare with me here. Thanks
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Old 02-14-2018, 01:53 AM
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Originally Posted by jdaugherty View Post
Thanks for all the replys o guess what I'm really lookong for is thw nice deep throaty sound! I love the way a cam sounds. I also dont race and have no intentions on doing so. So not looking to go crazy. I guess my 450-500 was far fetched so lets forget the hp gains, and get to what I'm really tryong to achieve. Witch is a deeper sound a little more throaty, and a cam but nothing to crazy just really want to hear it if that makes sense. Still learning so Don't really know what I'm talking about 100 peecent yet so just bare with me here. Thanks
Forget the cam. You will need a torque converter and trans cooler with a cam.
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Old 02-14-2018, 01:35 PM
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jdaugtery, Sir,

My suggestion would be to first figure out the current rear end ratio if its a 3:15 then a mild cam will be just fine for your car. ( you could go with a "stage one" set up or get a LS6 cam from one of the Z06 guys) a set of long tubes an x pipe and an axle back would be where I would suggest you start... you can add other stuff later. this can be done with the budget you suggested... but you will have to turn your own wrenches.

a "bigger cam" essentially moves the power band higher up in the RPM range the "lumpy idle that everyone likes is because at low rpm the car is not running very well.... its set up to hold the valves open for longer periods of time but at 3, 4, 5,000 rpm (when combustion events happen a lot faster due to engine speed) the valves are held open longer to try and get more air crammed into the engine before the next power stroke happens. this is simple explanation of how cams affect drivability....

bigger cams need a higher ratio gear to put it into its "happy place" (higher rpm) sooner.

Here is the trouble with an automatic.... with a bigger cam and gear drivability suffers... the torque converter in your car is set up for drivability (and fuel economy)...... with the stock cam in your car the "converter" allows the engine to run at idle without stalling. as you press on the gas it hydraulically "locks up" at around 1100-1300 rpm ......meaning the engine and the transmission are turning the same rpm...

(in a stick shift car you "slip the clutch" until the car is moving on its own then fully engage when the car wont "stall out")

in an automatic you can't "regulate" this lock up. It is dialed in with the design of the converter from the factory.

with that explanation out of the way lets look at a big cam...

say we choose vengeance racing Vindicator Camshaft...... this was lifted directly from their website; "specifications are 240/244 .605/.596 112 LSA. 2800-7000 Rpm Power Band. Explosive mid range and top end. This camshaft is our most popular creation yet. You can find this camshaft in some of the fastest LSX combinations in the world. Looking for 400 plus rwhp in your stock headed application?? The Vindicator is your answer. With more power under the curve than the other "larger camshafts" out there and explosive top end power the Vindicator is your answer. We suggest 4:10 rear gear for M6 or 4000+ Stall in A4. Computer tuning is required for optimal results. Dual springs are required. We suggest checking P/V on all applications."

The power does not start until 2800 rpm... with the lower gear in your car and the stock converter your car will ......cough... sputter.... buck and stall until you get to 2800 rpm.... for most street driving cars 1000 to 3000 rpm is where they spend the most amount of time with highway cruising and mild acceleration... as you read thru the description for this cam it suggests a high ratio (4.10 gears) and what is known as a "stall converter" that locks up at 4,000 rpm...

the higher ratio rear end gets the car into the cams useable rpm band and the "stall converter" slips the transmission for drivability until the engine "comes on cam" meaning its in its power band.... the problem with a "stall converter" is that is created a lot of extra heat because it doesn't fully engage until 4,000 rpm... so a transmission cooler is needed.

I hope this helps... I wanted to explain this to you so you understand the physics behind everyone's suggestions so far... and the reason for the suggestions they make (I guess its the old vocational instructor in me LOL! ) but don't get discouraged by some of the guys LOL'ing at the post....all of us on this board had to learn it at some point... us old guys sometimes forget that.

Last edited by ASRoff; 02-14-2018 at 01:45 PM.
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Old 02-14-2018, 03:39 PM
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Good, easy to understand clarifications of how everything works together!
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