Opinions on my P.port housings
11-05-2005, 09:53 PM
#21
Junior Member
Join Date: Oct 2005
Posts: 10
So, instead of tuning for power that peaks at redline, one should tune for power that peaks a few hundred RPM below redline, so that when you shift, you drop yourself down onto the high side of the other side of the powerband, instead of way down some hole on the other side of the RPM band.
If you have the luxury of choosing your gear ratios, then choose them in such a way that the closer you get to top speed, the shorter the drop between ratios. As was stated above, you want to maximize the amount of area of the power curve that falls between the shift points.
If ultimate top speed is what you are after, then your gearing should be such that top speed is just reached at peak HP RPM. If you notice that your car is not reaching its peak HP rpm in top gear, your gearing combined with your rearend ratio are too tall.
If your car can keep pulling past peak HP RPM while in top gear, that is not a bad thing, necessarily, because you are not always driving on flat roads, but it means your car has more top speed capability than it is presently geared to enjoy.
It's a matter of personal taste. Are your races run to find who can produce the highest top speed, no matter the distance, or over the course of a few miles to determine who can accelerate fastest?
Most races are of a "how far ahead one of us is when we both decide to back down" variety, thus, the real world requirements vary on a per-race basis.
The more ratios your transmission has, the more time each gear can spend in the fat part of the powerband, but also, the more time you spend shifting. BUT, due to the fact that ratios are capable of being spaced more closely, it is easier to shift faster, due to reduced difference in clutch RPM between one gear and the other.
Cool, huh?
If you want a spiky, peaky, powerband, that has ultimate HP with less consideration of ease of driveability, then, to do better in races, you will need more transmission gear ratios. And learn how to shift. Five one-second shifts will cost you five seconds of acceleration.
The new Ferrari autoshifters that use the paddles, one on each side of the steering wheel use up 0.2 seconds per shift.
If you have the luxury of choosing your gear ratios, then choose them in such a way that the closer you get to top speed, the shorter the drop between ratios. As was stated above, you want to maximize the amount of area of the power curve that falls between the shift points.
If ultimate top speed is what you are after, then your gearing should be such that top speed is just reached at peak HP RPM. If you notice that your car is not reaching its peak HP rpm in top gear, your gearing combined with your rearend ratio are too tall.
If your car can keep pulling past peak HP RPM while in top gear, that is not a bad thing, necessarily, because you are not always driving on flat roads, but it means your car has more top speed capability than it is presently geared to enjoy.
It's a matter of personal taste. Are your races run to find who can produce the highest top speed, no matter the distance, or over the course of a few miles to determine who can accelerate fastest?
Most races are of a "how far ahead one of us is when we both decide to back down" variety, thus, the real world requirements vary on a per-race basis.
The more ratios your transmission has, the more time each gear can spend in the fat part of the powerband, but also, the more time you spend shifting. BUT, due to the fact that ratios are capable of being spaced more closely, it is easier to shift faster, due to reduced difference in clutch RPM between one gear and the other.
Cool, huh?
If you want a spiky, peaky, powerband, that has ultimate HP with less consideration of ease of driveability, then, to do better in races, you will need more transmission gear ratios. And learn how to shift. Five one-second shifts will cost you five seconds of acceleration.
The new Ferrari autoshifters that use the paddles, one on each side of the steering wheel use up 0.2 seconds per shift.
11-05-2005, 11:13 PM
#22
Senior Member
Join Date: Jun 2004
Posts: 524
Originally Posted by Smilodon' post='775844' date='Nov 5 2005, 07:53 PM
So, instead of tuning for power that peaks at redline, one should tune for power that peaks a few hundred RPM below redline, so that when you shift, you drop yourself down onto the high side of the other side of the powerband, instead of way down some hole on the other side of the RPM band.
Never ceases to amaze me that many, many people do not get this.
I personally wouldn't even aim for peak power a only a few hundred below redline, unless you had a nice ultraclose gearset.
One of the winningest engine builders in the world doesn't give a crap about power. He aims for a big fat torque "hump" several hundred RPM below where the engine falls to after an upshift. Actually, he doesn't aim for anything based on a mere torque curve, he aims for best engine acceleration on a simulated-load dyno, and best recovery after an upshift yanks the RPM down and mucks up the resonance/inertial tuning in the manifolding. The torque curve more often that not will have that characteristic "hump" below the shift-to RPM, and somehow will rate a couple hundred horses less than the (slower) competition.
Power is not the end, it's a means to the end. Acceleration is the end. Yet so many people add power to the point that it hurts acceleration.
11-06-2005, 01:00 PM
#23
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Lynn E. Hanover' post='775833' date='Nov 5 2005, 07:26 PM
problems with broken parts. This usually a result of not knowing what goes on inside a transmission. There are people out there who rebuild transmissions every day and have little or no understanding of how they work.
In my opinion, broken forkes indicate abuse of a transmission punishable by not more than 6 months of confinement at hard labor.
Lynn E. Hanover
yeah they need a longer shifter on there.
on the left is the hub set, the inside bit is splined to the mainshaft, and the outside bit is the part where the shift fork rides on and it is what grabs the gear. centre is the synchro, and right is the gear
11-12-2005, 04:37 AM
#25
Senior Member
Thread Starter
Join Date: Jun 2003
Location: Denmark
Posts: 214
You are right Alex, these housings used to power my old FC N/A, hence the minor chrome flaking, im not too worried about it. Last compression test showed 122psi 
Though I am going to use 3mm carbon seals in this one, it might be different due to the lack of endpiece...
Though I am going to use 3mm carbon seals in this one, it might be different due to the lack of endpiece...
11-12-2005, 04:42 PM
#26
Senior Member
Join Date: Dec 2002
Location: fredneck MD
Posts: 4,107
Or, you can leave out the syncros all together ina dog ring style transmission.
I absoutly love my jerico dogmission. It is a joy to upshift, you can change gears as fast as you can shift it. It's also got nice tight gear ratios, so i dont loose too much RPM after the shift.
I absoutly love my jerico dogmission. It is a joy to upshift, you can change gears as fast as you can shift it. It's also got nice tight gear ratios, so i dont loose too much RPM after the shift.
11-13-2005, 07:14 AM
#28
Fabricator
Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by rfreeman27' post='777859' date='Nov 12 2005, 02:42 PM
Or, you can leave out the syncros all together ina dog ring style transmission.
I absoutly love my jerico dogmission. It is a joy to upshift, you can change gears as fast as you can shift it. It's also got nice tight gear ratios, so i dont loose too much RPM after the shift.
Could you post pictures of your adaptor system to get the Jerico onto the Mazda?
Thank you.
Lynn E. Hanover
11-13-2005, 11:11 AM
#29
Senior Member
Join Date: Dec 2002
Location: fredneck MD
Posts: 4,107
The adapter plate (provided by jerico) will bolt up to a mazda turbo bellhousing.
You retail the stock style clutch and hydrolics, Just need to source a 18spline style clutch disc. I ordered mine with the 'road race' rings and sliders, so downshifting will not be as much as a chore. A revmatch is all that is needed, But it will go into any gear at any rpm
I have the old style DR-4 trans. The new ones (DR-4-4)have split magnesium cases with o-ring seals, lighter and stronger gears, etc.
I just couldnt afford another 2,000 in transmission. This is more then I will ever really need anyways.
I can get an incar shot as well.
-bobby
You retail the stock style clutch and hydrolics, Just need to source a 18spline style clutch disc. I ordered mine with the 'road race' rings and sliders, so downshifting will not be as much as a chore. A revmatch is all that is needed, But it will go into any gear at any rpm
I have the old style DR-4 trans. The new ones (DR-4-4)have split magnesium cases with o-ring seals, lighter and stronger gears, etc.
I just couldnt afford another 2,000 in transmission. This is more then I will ever really need anyways.
I can get an incar shot as well.
-bobby
11-13-2005, 03:24 PM
#30
Fabricator
Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by rfreeman27' post='778023' date='Nov 13 2005, 09:11 AM
The adapter plate (provided by jerico) will bolt up to a mazda turbo bellhousing.
You retail the stock style clutch and hydrolics, Just need to source a 18spline style clutch disc. I ordered mine with the 'road race' rings and sliders, so downshifting will not be as much as a chore. A revmatch is all that is needed, But it will go into any gear at any rpm
I have the old style DR-4 trans. The new ones (DR-4-4)have split magnesium cases with o-ring seals, lighter and stronger gears, etc.
I just couldnt afford another 2,000 in transmission. This is more then I will ever really need anyways.
I can get an incar shot as well.
-bobby
That shot is fine for me.
How much total including the bell housing and adapter plate?
I have a Long shifter.
What ratios did you pick?
Thanks.
Lynn E. Hanover