Hp Reduction
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 851
Likes: 103
From: St Louis, MO
Hp Reduction
I recently had my car dyno tuned and got a base line of 290 wrhp. I installed an LS6 intake and a set of LG long tube headers and the rwhp only increased to about 301 rwhp. After tuning I increased another 10 hp.
At the time I added the intake manifold and the headers, I also switch my gears to 3:90 (mn6).
I am not happy with the 11 rwhp gain with the intake manifold and headers. Most of the info I read said the manifold would gain about 10 hp and the headers up to as much as 17 - 20 hp. I'm not even close.
The dyno chart did show a 17 - 20 maximum hp gain but not at maximum rpm. Is this how the manufactures rate their products?
I have a stock LS1 cam and heads. Do I need a bigger cam and better heads to get the full benefit from the intake manifold and headers?
How much rwhp could I have lost due to the 3:90 gears?
I appreciate any comments.
At the time I added the intake manifold and the headers, I also switch my gears to 3:90 (mn6).
I am not happy with the 11 rwhp gain with the intake manifold and headers. Most of the info I read said the manifold would gain about 10 hp and the headers up to as much as 17 - 20 hp. I'm not even close.
The dyno chart did show a 17 - 20 maximum hp gain but not at maximum rpm. Is this how the manufactures rate their products?
I have a stock LS1 cam and heads. Do I need a bigger cam and better heads to get the full benefit from the intake manifold and headers?
How much rwhp could I have lost due to the 3:90 gears?
I appreciate any comments.
Pro
Joined: May 2004
Posts: 673
Likes: 1
From: Pembroke Pines Florida
When I had my 2000 Coupe it had 52000 miles. Motor was stock. Only aftermarket was Corsa exhaust and a Vortex air filter. Mid range the RWHp was 306. Maybe the dyno is off or you have other problems.
Scott
Scott
Team Owner
Joined: Sep 2001
Posts: 23,283
Likes: 906
From: Lake Elsinore, CA
Base - 290 rwhp
Intake/headers/3.90 gears - 301 rwhp
Tuning - 311 rwhp
If I understand your progression, that's what you gained. That's really not bad considering you're stock otherwise and running the 3.90 gears. A 21 rwhp gain is respectable if you factor in up to 8-10 rwhp "lost" to the gears. Plus you don't list your torque values which are just as relevant when you discuss these kinds of mods. Also, you need to look at "area under the curve" when it comes to performance gains. Moderate increases across the board can produce better overall acceleration numbers than ostensibly impressive peak values that span a narrow range.
HP/TQ gains quoted by vendors are generally beased on best-case configurations. The better your engine breathes, the more benefit it will gain from intake and exhaust enhancements. A healthy h/c package would take better advantage of those mods. You've got a good base to start with.
Intake/headers/3.90 gears - 301 rwhp
Tuning - 311 rwhp
If I understand your progression, that's what you gained. That's really not bad considering you're stock otherwise and running the 3.90 gears. A 21 rwhp gain is respectable if you factor in up to 8-10 rwhp "lost" to the gears. Plus you don't list your torque values which are just as relevant when you discuss these kinds of mods. Also, you need to look at "area under the curve" when it comes to performance gains. Moderate increases across the board can produce better overall acceleration numbers than ostensibly impressive peak values that span a narrow range.
HP/TQ gains quoted by vendors are generally beased on best-case configurations. The better your engine breathes, the more benefit it will gain from intake and exhaust enhancements. A healthy h/c package would take better advantage of those mods. You've got a good base to start with.
Last edited by Patches; Aug 25, 2004 at 07:59 AM.
Team Owner
Joined: Mar 2002
Posts: 47,647
Likes: 1
From: Queens, New York Life begins at 183 mph....
St. Jude Donor '08-'09
You definitely need an aftermarket air intake like a blackwing or a vararam. If I'm reading your post correctly, all you have is the gearing, the ls6 manifold and the headers. The gearing will actually lower your hp numbers by like 10 hp. The headers can't really do much if your engine is still breathing through the stock filter, same goes for the Ls6 manifold. You also have to remember that you have a 98 which has less hp and more importantly less torque than a 2000+ C5. If you are looking at numbers quoted by other people who have 2000s and up, they already have a few more ponies to start with. I'd definitely get the air intake replaced. Its not expensive and it may help you get into the 320's That's pretty respectable. One other note, LG claims 17-20 hp gains *but that's a best case scenario with no cats. You most likely puts cats on there which accounts for about 5-10 hp loss from their best numbers.
Last edited by alex1217; Aug 25, 2004 at 08:19 AM.
Le Mans Master
Joined: Sep 2003
Posts: 5,374
Likes: 0
From: Jacksonville Florida
If it's any help for comparison I've got an 00 coupe, A4 3.15 with the following -
K&N FIPK
Granitelli MAF
WCC TB
Z06 intake manifold
Corsa touring exhaust (x-pipe)
After tuning had 314.3 RWHP 314.7 RWTQ on a warm (not hot) day. Using an estimated 18% loss FW to RW I started with 282.9 RWHP stock so that's a 31.4 RWHP gain with just those mods and tuning. Some add a few more HP to account for temp and/or the dyno machine itself, but these are the raw numbers from the runs.
If I undertand it (also) you got a final figure of 311RWHP which doesn't sound too bad for what is on your car. You've probably got far more torque than I do, too. And that counts A LOT on the road.
Hope this helps.
K&N FIPK
Granitelli MAF
WCC TB
Z06 intake manifold
Corsa touring exhaust (x-pipe)
After tuning had 314.3 RWHP 314.7 RWTQ on a warm (not hot) day. Using an estimated 18% loss FW to RW I started with 282.9 RWHP stock so that's a 31.4 RWHP gain with just those mods and tuning. Some add a few more HP to account for temp and/or the dyno machine itself, but these are the raw numbers from the runs.
If I undertand it (also) you got a final figure of 311RWHP which doesn't sound too bad for what is on your car. You've probably got far more torque than I do, too. And that counts A LOT on the road.
Hope this helps.
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 851
Likes: 103
From: St Louis, MO
HP reduction
Originally Posted by alex1217
You definitely need an aftermarket air intake like a blackwing or a vararam. If I'm reading your post correctly, all you have is the gearing, the ls6 manifold and the headers. The gearing will actually lower your hp numbers by like 10 hp. The headers can't really do much if your engine is still breathing through the stock filter, same goes for the Ls6 manifold. You also have to remember that you have a 98 which has less hp and more importantly less torque than a 2000+ C5. If you are looking at numbers quoted by other people who have 2000s and up, they already have a few more ponies to start with. I'd definitely get the air intake replaced. Its not expensive and it may help you get into the 320's That's pretty respectable. One other note, LG claims 17-20 hp gains *but that's a best case scenario with no cats. You most likely puts cats on there which accounts for about 5-10 hp loss from their best numbers.
I'm assuming stock rwhp is about 275 on a 98 and I was at 289 rwhp before adding the manifold, headers and gears.
I appreciate the info on the loss of hp from the gears. I was expecting more hp gain but now knowing I would have about an extra 10 hp at max. rpm and a peak hp of about 37 rwhp if I still had the stock gear, I feel better about the mods.
Thanks for the help.
