ways to reduce hp?
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chillin the most
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ways to reduce hp?
ok so heres the deal: I am going to try racing in the American Iron Series this year. instead of them having specific rules for an engine combo the have a power to weight rule.
9.5:1 hp
9:1 tq.
my car weighs 3210 right now and is putting down 348 hp and 338 tq to the wheels. I think I have to knock about 20 hp out of it to be on the safe side. I already plan on putting a paper air filter on it in place of the K&N, but I dont think it will be nearly enough, so any sugg. on how to know out a few more hp?
sounds crazy, asking how to reduce hp, eh
btw, I really do not want to add any ballast, or not more than say 30 lbs.
9.5:1 hp
9:1 tq.
my car weighs 3210 right now and is putting down 348 hp and 338 tq to the wheels. I think I have to knock about 20 hp out of it to be on the safe side. I already plan on putting a paper air filter on it in place of the K&N, but I dont think it will be nearly enough, so any sugg. on how to know out a few more hp?
sounds crazy, asking how to reduce hp, eh
btw, I really do not want to add any ballast, or not more than say 30 lbs.
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Last edited by bubbleheadM3; Dec 19, 2003 at 01:29 PM.
OUCH!!!
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You could go with a disc type muffler system on the end of your exhaust pipes. Alot of race cars use them to meet sound regulations at various tracks. More discs = less restrictive (more power)... less discs= more restrictive (less power).
Keep in mind the fewer disks you use the more backpressure you are adding and that will affect torque as well...
pull a touch of timing out?
Put some sort of plate between the throttle body and intake that will restrict airflow slightly and tailor the opening to get the power you want? (like a restrictor plate in nascar....)
http://www.supertrappind.com/Automot...otive_page.htm
http://www.supertrappind.com/Automot...%202002-10.pdf
Keep in mind the fewer disks you use the more backpressure you are adding and that will affect torque as well...
pull a touch of timing out?
Put some sort of plate between the throttle body and intake that will restrict airflow slightly and tailor the opening to get the power you want? (like a restrictor plate in nascar....)
http://www.supertrappind.com/Automot...otive_page.htm
http://www.supertrappind.com/Automot...%202002-10.pdf
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Well, I would take a few degrees timing out of it. Actually since you run a carb and I'm assuming a non electronic distributor, I would get a curve kit that would allow for more initial advance (to keep torque), but wouldn't advance much at higher RPM's (to keep max power low). Or if you do run an electronic distributor, a timing retard for the after race dyno pull could be handy 
.
Fatten up the carb a bit. This will let the motor run cooler for reliability but also lose a bit of power.
Run a thicker oil.
Play around with cam timing so the thing makes alot of power at a lower RPM and gear accordingly.
Run a manual fan on it. Will kill probably close to 10hp, and let the motor run cooler all while being simpler.
But you're looking at this all wrong. You don't need to make less HP, just less HP while they are dynoing it
You could run a huge ass alternator (more HP to turn) and somehow create a huge load on a switch right before they throw it on the dyno. That would rob a couple more HP.
As I mentioned before, use an ignition system with a retard and a hidden switch.
Hell, you can safely run up to about 10% nitromethane and make an extra 10%. Do they let you refuel before the dyno?
Maybe have a line loc that you could apply some brake pressure so the wheels drag during the dyno run?
. Fatten up the carb a bit. This will let the motor run cooler for reliability but also lose a bit of power.
Run a thicker oil.
Play around with cam timing so the thing makes alot of power at a lower RPM and gear accordingly.
Run a manual fan on it. Will kill probably close to 10hp, and let the motor run cooler all while being simpler.
But you're looking at this all wrong. You don't need to make less HP, just less HP while they are dynoing it
You could run a huge ass alternator (more HP to turn) and somehow create a huge load on a switch right before they throw it on the dyno. That would rob a couple more HP.
As I mentioned before, use an ignition system with a retard and a hidden switch.
Hell, you can safely run up to about 10% nitromethane and make an extra 10%. Do they let you refuel before the dyno?
Maybe have a line loc that you could apply some brake pressure so the wheels drag during the dyno run?
Last edited by Fordified; Dec 18, 2003 at 05:00 PM.
Driver
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Why not add weight to the car? You can add it where you want and help the car turn better. Or like Leonard said use a restrictor plate I dont think it would be too hard to make one that would be one of the easiest things to do unless you only plan to race in that series once or twice.
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You never add weight unless you HAVE to.
You're better off being at minimum weight than being over with the weight where you 'want' it. The bottom line is you don't 'want' weight. Being at minimum weight is a good thing. Tires last longer and you have less car / sqin of contact patch. Brakes last longer and have less heating issues. It's easier on the drivetrain and engine.
(Adding weight where you want it is only applicable when you are below the minimum weight and need to ballast up.
I'd go with restricting airflow before I add a manual fan. It's rotating mass. Rotating mass is bad.. it just adds more stress to the engine.
A cam change might be your best bet. Something a less peaky with a broader power band would be ideal.
You're better off being at minimum weight than being over with the weight where you 'want' it. The bottom line is you don't 'want' weight. Being at minimum weight is a good thing. Tires last longer and you have less car / sqin of contact patch. Brakes last longer and have less heating issues. It's easier on the drivetrain and engine.
(Adding weight where you want it is only applicable when you are below the minimum weight and need to ballast up.
I'd go with restricting airflow before I add a manual fan. It's rotating mass. Rotating mass is bad.. it just adds more stress to the engine.
A cam change might be your best bet. Something a less peaky with a broader power band would be ideal.
Thread Starter
chillin the most
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alot of good ideas, thanks. Leonard is definatly right I do not want to add weight, although since I am a bit of a fat ass(235lbs) a few pounds in the right rear to offset my weight wouldnt be to bad and will get my cross weights closer to even.
force fed had some good ideas but I believe they have a rule stating "no ignition retard devices allowed."I'll have to take another look at the rules. I already run a 15w50 oil too.
but I think I might just be ok w/ a paper filter and some bigger jetting, plus a minimal amout of ballast just to be on the safe side, say like 25 lbs.
thank for the ideas though and I'll keep you guys posted on how it turns out.
force fed had some good ideas but I believe they have a rule stating "no ignition retard devices allowed."I'll have to take another look at the rules. I already run a 15w50 oil too.
but I think I might just be ok w/ a paper filter and some bigger jetting, plus a minimal amout of ballast just to be on the safe side, say like 25 lbs.
thank for the ideas though and I'll keep you guys posted on how it turns out.
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Originally posted by bubbleheadM3
force fed had some good ideas but I believe they have a rule stating "no ignition retard devices allowed."I'll have to take another look at the rules. I already run a 15w50 oil too.
force fed had some good ideas but I believe they have a rule stating "no ignition retard devices allowed."I'll have to take another look at the rules. I already run a 15w50 oil too.
Whats the saying, "its only cheating if you get caught".
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dont run a paper filter they are the worst. Plus it won't drop to much horsepower. But yes the easist way is get a machicist to make you a "restrictor plate" well you got the m3? and that has what 6 intakes soo it might be kinda hard to make it for that. So i would go with the disk type muffler.
but dont go paper airfilter that just lets everything by pass your filter
-garrett
but dont go paper airfilter that just lets everything by pass your filter
-garrett
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Why not swap cams? I know it's a little more work, but why mess with a lot of little things when you could just change one item and be right where you want to be.
I do like the idea of putting weight where you need it, in order to improve cross weight, but I am sure that you running a tight suspension. I would think that it would take more than 20 pounds to make any real difference in the cross. How much weight would you need to add? Also, do you have your own scales to measure that down after you get HP dynos? Also, if you are going that far with weight, wouldn't you want to change it, since each track has a different setup? Seems like a lot of changes, but that's OK too.
However, a nice custom ground cam to deliver peak HP and torque in the RPM range you would want. Any ways, just a thought.
I do like the idea of putting weight where you need it, in order to improve cross weight, but I am sure that you running a tight suspension. I would think that it would take more than 20 pounds to make any real difference in the cross. How much weight would you need to add? Also, do you have your own scales to measure that down after you get HP dynos? Also, if you are going that far with weight, wouldn't you want to change it, since each track has a different setup? Seems like a lot of changes, but that's OK too.
However, a nice custom ground cam to deliver peak HP and torque in the RPM range you would want. Any ways, just a thought.
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bubbleheadM3,
Do you have scales if so what is the total weight and left and right weight and the nose, and cross?
OldMan you are right putting in a smaller cam would be good. I kind of forgot that if you put on a restrictor plate you would need to change the cam anyway to get back into your power range for the amount of air you are going to be pulling in.
Weight would probably be the easiest how much would you need to add to get 9.5:1 ??
If you have scales you can do it jsut right. I belive bmws are already 50/50 weight distributed. So you would be adding weight near the front and in the rear.
then you run into another problem with adding weight then you VCG is all thrown off.
soo probably just changing something probably the exhaust disk would be the best bet
-garrett
Do you have scales if so what is the total weight and left and right weight and the nose, and cross?
OldMan you are right putting in a smaller cam would be good. I kind of forgot that if you put on a restrictor plate you would need to change the cam anyway to get back into your power range for the amount of air you are going to be pulling in.
Weight would probably be the easiest how much would you need to add to get 9.5:1 ??
If you have scales you can do it jsut right. I belive bmws are already 50/50 weight distributed. So you would be adding weight near the front and in the rear.
then you run into another problem with adding weight then you VCG is all thrown off.
soo probably just changing something probably the exhaust disk would be the best bet
-garrett
