Low horsepower numbers...=*(
Jeff and Peter,
You are correct about me having an aftermarket intercooler. My point was that you can make good HP numbers with a stock airbox.
I have a stock main cat with the inlet and outlet opened up to a full 2 1/2" The cat comes with both of the flanges welded on the inside. These welds reduce the openings to just over 2". I re-welded the flanges on the outside, and ground down the inside welds. I was able to feel a very small difference in power because of this. I recommend this mod to anyone with a stock cat. Get the flanges welded all the way around the outside first, then carefully grind away the inside welds. It's not an overwhelming difference, but every little bit helps
I am currently running 13 psi.
I do not have any dyno numbers. I base my rwhp estimate on several 20-120 runs with a bone stock 2002 Z06 Corvette with low mileage, and a good driver. Each run (with a fair start) resulted in the Z06 beating me by 1/2 car length. At the time I was running 12 1/2 psi.
The Z06 claims 405 hp which should be about 345 rwhp. Weighing in at about 3100 lbs, that gives the Z06 a weight/HP ratio of 9/1. With a 9/1 ratio, and a 2800 lb FD, rwhp calculates at 311. At 13 psi (instead of 12 1/2), I call my car even with the Z06. I am not claiming 311 rwhp. I am claiming "somewhere around" 300 rwhp.
I know this isn't a very good way to measure rwhp. That's why it is just an estimate.
You are correct about me having an aftermarket intercooler. My point was that you can make good HP numbers with a stock airbox.
I have a stock main cat with the inlet and outlet opened up to a full 2 1/2" The cat comes with both of the flanges welded on the inside. These welds reduce the openings to just over 2". I re-welded the flanges on the outside, and ground down the inside welds. I was able to feel a very small difference in power because of this. I recommend this mod to anyone with a stock cat. Get the flanges welded all the way around the outside first, then carefully grind away the inside welds. It's not an overwhelming difference, but every little bit helps
I am currently running 13 psi.
I do not have any dyno numbers. I base my rwhp estimate on several 20-120 runs with a bone stock 2002 Z06 Corvette with low mileage, and a good driver. Each run (with a fair start) resulted in the Z06 beating me by 1/2 car length. At the time I was running 12 1/2 psi.
The Z06 claims 405 hp which should be about 345 rwhp. Weighing in at about 3100 lbs, that gives the Z06 a weight/HP ratio of 9/1. With a 9/1 ratio, and a 2800 lb FD, rwhp calculates at 311. At 13 psi (instead of 12 1/2), I call my car even with the Z06. I am not claiming 311 rwhp. I am claiming "somewhere around" 300 rwhp.
I know this isn't a very good way to measure rwhp. That's why it is just an estimate.
Last edited by adam c; Mar 8, 2005 at 11:18 PM.
Originally Posted by adam c
Jeff and Peter,
You are correct about me having an aftermarket intercooler. My point was that you can make good HP numbers with a stock airbox.
I have a stock main cat with the inlet and outlet opened up to a full 2 1/2" The cat comes with both of the flanges welded on the inside. These welds reduce the openings to just over 2". I re-welded the flanges on the outside, and ground down the inside welds. I was able to feel a very small difference in power because of this. I recommend this mod to anyone with a stock cat. Get the flanges welded all the way around the outside first, then carefully grind away the inside welds. It's not an overwhelming difference, but every little bit helps
I am currently running 13 psi.
I do not have any dyno numbers. I base my rwhp estimate on several 20-120 runs with a bone stock 2002 Z06 Corvette with low mileage, and a good driver. Each run (with a fair start) resulted in the Z06 beating me by 1/2 car length. At the time I was running 12 1/2 psi.
The Z06 claims 405 hp which should be about 345 rwhp. Weighing in at about 3100 lbs, that gives the Z06 a weight/HP ratio of 9/1. With a 9/1 ratio, and a 2800 lb FD, rwhp calculates at 311. At 13 psi (instead of 12 1/2), I call my car even with the Z06. I am not claiming 311 rwhp. I am claiming "somewhere around" 300 rwhp.
I know this isn't a very good way to measure rwhp. That's why it is just an estimate.
You are correct about me having an aftermarket intercooler. My point was that you can make good HP numbers with a stock airbox.
I have a stock main cat with the inlet and outlet opened up to a full 2 1/2" The cat comes with both of the flanges welded on the inside. These welds reduce the openings to just over 2". I re-welded the flanges on the outside, and ground down the inside welds. I was able to feel a very small difference in power because of this. I recommend this mod to anyone with a stock cat. Get the flanges welded all the way around the outside first, then carefully grind away the inside welds. It's not an overwhelming difference, but every little bit helps
I am currently running 13 psi.
I do not have any dyno numbers. I base my rwhp estimate on several 20-120 runs with a bone stock 2002 Z06 Corvette with low mileage, and a good driver. Each run (with a fair start) resulted in the Z06 beating me by 1/2 car length. At the time I was running 12 1/2 psi.
The Z06 claims 405 hp which should be about 345 rwhp. Weighing in at about 3100 lbs, that gives the Z06 a weight/HP ratio of 9/1. With a 9/1 ratio, and a 2800 lb FD, rwhp calculates at 311. At 13 psi (instead of 12 1/2), I call my car even with the Z06. I am not claiming 311 rwhp. I am claiming "somewhere around" 300 rwhp.
I know this isn't a very good way to measure rwhp. That's why it is just an estimate.
I just dynoed a couple weeks ago.
My mods that matter are:
Pettit intake
SR stock mount IC
Bones DP
SR high flow
RB cat back
PFC
on a stock port.
The first run was 250 running 12psi
I took off the cat, poured out the brick that was already broken up due to 5+ years of rotary richness cooking it and put the now gutted cat back on
Hit 307 @ 14.3psi. Re-adjusted boost for 12psi and still put down 290.
I would be willing to bet your problem is the cat. I have my doubts that the crappy stock IC is choking that much power. Neither the IC or the intake made any difference that I could feel when I put them in. I think 240 is low for your setup, and my guess is the cat is the biggest contributor, probably broken or otherwise plugged.
My mods that matter are:
Pettit intake
SR stock mount IC
Bones DP
SR high flow
RB cat back
PFC
on a stock port.
The first run was 250 running 12psi
I took off the cat, poured out the brick that was already broken up due to 5+ years of rotary richness cooking it and put the now gutted cat back on
Hit 307 @ 14.3psi. Re-adjusted boost for 12psi and still put down 290.
I would be willing to bet your problem is the cat. I have my doubts that the crappy stock IC is choking that much power. Neither the IC or the intake made any difference that I could feel when I put them in. I think 240 is low for your setup, and my guess is the cat is the biggest contributor, probably broken or otherwise plugged.
Well, the almost 60HP wasnt really that I gutted the cat. It is more that the cat was toast and I just had to remove it and pour the already broken up crap out. It was very plugged up. I think a cat in good condition would have been able to still pull 280 for me.
Eats, Sleeps, Dreams Rotary
Joined: Feb 2002
Posts: 3,045
Likes: 2
From: North Coast
I dont think you are way off par.
couple years ago with Intake / DP / Exhaust / Efini Y-Pipe / PFC (stock IC & stock cat)
Chances are your stock cat may be a little more restrictive from clogging.
couple years ago with Intake / DP / Exhaust / Efini Y-Pipe / PFC (stock IC & stock cat)
Chances are your stock cat may be a little more restrictive from clogging.
Last edited by apneablue; Mar 9, 2005 at 09:46 AM.
Originally Posted by Mr rx-7 tt
The dyno is your friend.
Regarding that cat mod, I did some calculations. With the factory welds, the openings in the inlet and outlet to the cat are about 2 1/8". The mod will open it up to a full 2 1/2". That is a 39% increase in the size of both openings. That has to help the cat flow better .......... unless it is clogged up
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