My RWHP Goal

**karpetcm** · 12-11-2008, 07:15 AM

Well i have a goal to hit about 320rwhp and im hoping i can do that. So far i have hooker muffler, exhuast cut out, Slp lid, K&N filter, TB bypass. Im gonna put on 160 thermo, Lsx Tune, TB porting and Pulley with my 4.10's but the gears wont add any RWHP. With the mods above and assuming i start at 290rwhp from my 6speed 01 Z28 and going with the least amount of hp these will give me 5hp from the lid and filter, 5hp from the exhuast cut out and muffler, 5hp from the tune, 5hp from pulley, tb bypass, 160 thermo and 5hp from throttle body porting with a smooth bellow.

With those mods im hoping ill be atleast 315-320rwhp does that sound about right to you guys what do you guys have and what have you put down on the dyno. Im not gonna do headers since ive had bad luck with them in the past on all my cars, plus in the future i will be going with nitrous wet system so that should more then make up for it.

**tbias** · 12-11-2008, 07:37 AM

i think you'll be a liittle north of 320.

**SSwt00SS** · 12-11-2008, 08:01 AM

the 4.10's will eat more power than you think...

if you have not done a base pull to get your numbers, who knows what your starting point is...

i think with what you have and what you plan to do, you will be under 320rwhp. if you added some LT's to your list, then i think youll meet and surpass your goal...

with what you have done, there is no need for a tune at this time. it wouldnt really benefit you...

**karpetcm** · 12-11-2008, 08:23 AM

just curious on the 4.10's how do you lose power on the dyno? and its not a stab back at you at all ive heard this before, i know from races that i did when i had my 01 SS with the same car i went up against with the 4.10's it felt like i was slower in the top end and i dont mean speed i mean rwhp. My 1st and 2nd gears were blazin fast but once i got up in the gears the top end was a bit less i noticed i was not pulling as hard on the same car above 5000rpms as i did before. I brought this issue up to Hoopers Rear Ends as to what may cause that and they said it will not effect your rwhp at at all. Ive also brought this up with others but no one really gives me a definite answer on this issue.

The only logically explanation i can come up with is since it has more teeth on the gears it will hinder it a bit but even as i say that its still not valid enough for me to believe, i just dont know. Also i forgot to mention when i had my 93Z put on the dyno and asked the guy there will 4.10's rob power on the dyno he said it will not, funny thing is my 93Z put down 266-267rwhp on 3 different days on the dyno and once i went to 3.42's it pulled 284-289rwhp. Even at 266rwhp i was one of the highest if not right up there with the other regular bolt on LT1's so even though i was disappointed at the numbers i wasnt too far off from the other LT1's on that dyno day. I recieved a email a while ago and im gonna try to find it but even this email didnt really hit home with me even though it might makes sense to alot of other people ill try to find it and post it here.

**karpetcm** · 12-11-2008, 08:33 AM

Found it, this is on my 93Z which had a 6speed and came from the factory with 2.73 gears.

Sorry it is so late, we been very busy lately.

To answer your question, you will not lose horsepower in the top end. Your horsepower will be lower on a dyno, due to less effort needed to turn the wheels. Your top speed may become lower aerodynamically, if you are trying to reach over 160 MPH. Your car will however excellerate much faster from a dead stop. This is why drag racers use lower gears (4.11 upto 5.13), and they can also add mph to their top speed by increasing the tire diameter with those gears (26" upto 30"). Hope this helps.
----- Original Message -----
From: Mike Karapetian
To: Jenibella@adelphia.net
Sent: Tuesday, July 18, 2006 8:33 PM

Hi, i wanted to say i just signed up under karpetcm. I wanted to ask you since you guys know what your doin. I want to change my rear end from a 2:73 gears to 4:10 gears i have a 1993 camaro z28 6speed. Will i lose any top end horsepower, ive gotten alot of opinion on this but wanted to ask a professional on this matter. If you can help me id really appreciate it and sorry to bug.

**BlueMagicSS** · 12-11-2008, 12:00 PM

4.10's give you a better take off and more "power" on the bottom end of the RPM spectrum... not sure how to explain it further, but you will lose top end speed... and a few hp #'s not much though

**BlueMagicSS** · 12-11-2008, 12:02 PM

Also.... you can get some SMOG legal shorties and you won't have any problems at all with clearance, police or anything... you can reuse your stock y-pipe... but you should be somewhere near the 320 mark. when I dynoed stock with a cutout I had 316HP and 327 FTlbs of TQ

**karpetcm** · 12-11-2008, 12:17 PM

I wanted to go with the shorty headers but i heard that the stock ones on the 01-02 flow just as well and not really worth much gain if you get any from them. I figured i could possibly go with an ORY and that will flow better then the stock one especially with the cats gone, after discussing that as well people said its not worth taking the cats off and they flow well enough for the set up i have.

**hutch1999** · 12-11-2008, 12:20 PM

you should be close to your mark

**SSwt00SS** · 12-11-2008, 12:24 PM

gears do not add power...

when you step to a lower/deeper set of gears, youre trading top speed/top end "pull" for quicker acceleration...

for example, if you have an M6 car w/3.42 gears, the driveshaft will turn 3.42 times per one revolution of the wheels. when you go to 4.10 it takes more revolutions of the driveshaft to turn the wheels one time. the reason you will show a loss of power on a dyno is because now there is more parasitic drivetrain loss. in reality the power is the same, but the deeper gearing has allowed the end to still be in the meat of the powerband when shifting into the next gear...

youre tricked into thinking that the your car has more 'power' down low but that is just the advantage of going to a lower set of gears. your car just accelerates quicker than before...

typical HP loss on a dyno going from 3.42 to 4.10 can be between 15-20 HP in a 10-bolt. you can expect even more to be lost when upgrading the rear to a 9" or 12 bolt, respectively...

**Hi-Po** · 12-11-2008, 12:55 PM

Originally Posted by karpetcm

. Im not gonna do headers since ive had bad luck with them in the past on all my cars, plus in the future i will be going with nitrous wet system so that should more then make up for it.

Its time to start having good luck .You NEED headers. It should be one of your first mods with out a doubt. ANY mod you do now, later, before... will give you more HP if your engine can get the spent gases OUT EASIER. Plain and simple, get headers.

Originally Posted by karpetcm

I wanted to go with the shorty headers but i heard that the stock ones on the 01-02 flow just as well and not really worth much gain if you get any from them. I figured i could possibly go with an ORY and that will flow better then the stock one especially with the cats gone, after discussing that as well people said its not worth taking the cats off and they flow well enough for the set up i have.

Shorty headers are worthless. Your stock manifolds flow shit. You need to get them off. Dont listen to people who tell you to leave those manifolds on. Get headers.

Originally Posted by SSwt00SS

gears do not add power...

when you step to a lower/deeper set of gears, youre trading top speed/top end "pull" for quicker acceleration...

for example, if you have an M6 car w/3.42 gears, the driveshaft will turn 3.42 times per one revolution of the wheels. when you go to 4.10 it takes more revolutions of the driveshaft to turn the wheels one time. the reason you will show a loss of power on a dyno is because now there is more parasitic drivetrain loss. in reality the power is the same, but the deeper gearing has allowed the end to still be in the meat of the powerband when shifting into the next gear...

youre tricked into thinking that the your car has more 'power' down low but that is just the advantage of going to a lower set of gears. your car just accelerates quicker than before...

typical HP loss on a dyno going from 3.42 to 4.10 can be between 15-20 HP in a 10-bolt. you can expect even more to be lost when upgrading the rear to a 9" or 12 bolt, respectively...

gears are awesome. I really want 4.10's in my 12 bolt instead of the 3.73's. Im just not comfortable setting up a 12 bolt. If it was a 9", That center section would be out right now no doubt.

You will be pretty close to your goal, But I highly doubt with out headers you will hit your mark.

**BlueMagicSS** · 12-11-2008, 04:54 PM

Originally Posted by SSwt00SS

gears do not add power...

when you step to a lower/deeper set of gears, youre trading top speed/top end "pull" for quicker acceleration...

for example, if you have an M6 car w/3.42 gears, the driveshaft will turn 3.42 times per one revolution of the wheels. when you go to 4.10 it takes more revolutions of the driveshaft to turn the wheels one time. the reason you will show a loss of power on a dyno is because now there is more parasitic drivetrain loss. in reality the power is the same, but the deeper gearing has allowed the end to still be in the meat of the powerband when shifting into the next gear...

youre tricked into thinking that the your car has more 'power' down low but that is just the advantage of going to a lower set of gears. your car just accelerates quicker than before...

typical HP loss on a dyno going from 3.42 to 4.10 can be between 15-20 HP in a 10-bolt. you can expect even more to be lost when upgrading the rear to a 9" or 12 bolt, respectively...

YEAH..... WHAT HE SAID!!! That's what I was tryna say earlier

**02Sweet** · 12-11-2008, 05:30 PM

Originally Posted by SSwt00SS

gears do not add power...

when you step to a lower/deeper set of gears, youre trading top speed/top end "pull" for quicker acceleration...

for example, if you have an M6 car w/3.42 gears, the driveshaft will turn 3.42 times per one revolution of the wheels. when you go to 4.10 it takes more revolutions of the driveshaft to turn the wheels one time. the reason you will show a loss of power on a dyno is because now there is more parasitic drivetrain loss. in reality the power is the same, but the deeper gearing has allowed the end to still be in the meat of the powerband when shifting into the next gear...

youre tricked into thinking that the your car has more 'power' down low but that is just the advantage of going to a lower set of gears. your car just accelerates quicker than before...

typical HP loss on a dyno going from 3.42 to 4.10 can be between 15-20 HP in a 10-bolt. you can expect even more to be lost when upgrading the rear to a 9" or 12 bolt, respectively...

well put

**INMY01TA** · 12-11-2008, 07:21 PM

My 01 Trans Am laid down 338rwhp with Mac mid length headers, lid, ASP pulley, and 4:10s in the 10 bolt on a Dynojet.

**WS6ICK2K** · 12-11-2008, 07:31 PM

Originally Posted by INMY01TA

My 01 Trans Am laid down 338rwhp with Mac mid length headers, lid, ASP pulley, and 4:10s in the 10 bolt on a Dynojet.

Good numbers for those mods.

**karpetcm** · 01-27-2009, 08:18 PM

just got my re tune done, my car was pinging bad and now its alot better. I cant wait to gut the cats and get to the dyno and see what happens. I still need to install my 4.10's but that wont show anything on the dyno.

**0rion** · 01-27-2009, 09:44 PM

Originally Posted by karpetcm

just got my re tune done, my car was pinging bad and now its alot better. I cant wait to gut the cats and get to the dyno and see what happens. I still need to install my 4.10's but that wont show anything on the dyno.

when you do get it to the dyno make sure you update us.....I'm curious to see if you'll make your mark. These cars are kinda all over HP wise. Some cars will dyno pretty low stock and some will be at your goal stock. Hard to say. My gut wants to say you'll be a little lower than you expect with those mods but it could really be anywhere. If you don't get it just have the dyno guy fudge the numbers and he can get it to say whatever you want it to.

**sct771** · 01-28-2009, 12:24 AM

Find out what type of dyno they are using. Mustang or Dynojet because that will make a difference too. Dynojets typically will give a more inflated number of horsepower due to the fact that all it reads is how many times those rollers rotate and other factors that im not aware of. Dynojets are also affected by temperature and humidity and the rear gear ratio that you have set up in the car will either help you or hurt you. Ei: a car with 3:42 gears is gonna make more power on the dynojet compared to the same car with 4:10 because its based on revolutions of those rollers and the car with lower gears can spin them more times. Mustang dyno's can be fooled to inflate HP numbers because it asks you to input a weight of your vehicle so if you put a lighter weight than what you actually have that will also give you a higher horsepower rating.

**karpetcm** · 01-28-2009, 06:52 AM

Im more then likey going to go with a dyna pack, the only thing i dont like about them is i know of one shop that does it and they messed up my rims taking them off last time, scratched the crap out of one. Luckly i was able to sand and polish it out. Worse case then ill just take it to a regular dyno, rollers. Alot of people told me dyna pack is way more accurate then the standard dyno machines but honestly i put my 93Z on the dyno 5 times, 3 times on a standard dyno and 2 times on a dyno pack and on the standard i pulled 289 rwhp before my 4.10 swap 269rwhp and 267 rwhp on a dyna pack i pulled 266rwhp. The 1st 289 rwhp was before taking timing out to run nitrous after timing was pulled my numbers dropped but stayed consistant pretty much on both dyno machines. What was a huge suprise my 01 E46 M3 6speed pulled 310.7rwhp on a dyno pack with the regular bolt ons and i wasnt expecting that from the car or the dyna pack either but i shouldnt be suprised through past experiences.

If i can hit about 320rwhp i will be happy, considering and all this is a guess till i dyno that the car stock pulls 295rwhp, no cats, exhuast cut out, hooker muffler hopefully will give me about 10rwhp and then SLP lid, K&N filter, TB bypass, Ported Throttle body, Underdrive pulley, 160 thermo and LSx Tune will probably give me another 15 rwhp combined total for those. Dont know will see what happens im sure ill be pretty disappointed but ill let you guys know i havent yet installed the 4.10's and i wont be for another couple of months so they wont be on the car when i take it to the dyno. Just got my tune done by Steve at LSx tune and the car runs alot stronger mid and top so hopefully i can reach my goal.

**karpetcm** · 01-29-2009, 08:36 AM

Does anyone know of a good rear end shop here is southern california close to glendale area. Ive asked this question several times before and since im not able to post this for some reason in general or drivetrain i thought i would ask this here, please help.