how to get 270hp out of an S5 n/a?
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From: n
Originally posted by bill Shurvinton
If you use a fixed %age for friction loss going from flywheel to rear wheel you really do not know much about frictional losses. Rear wheel HP is a dreadful metric, especially given the calibration state of most dynos.
If you use a fixed %age for friction loss going from flywheel to rear wheel you really do not know much about frictional losses. Rear wheel HP is a dreadful metric, especially given the calibration state of most dynos.
That 15% is an average, and most experts agree it's a good number to use for RWD platforms.  Personally, I've seen a 1993 FD make 12.5% friction loss off a DynoJet 248C - the FD was using all redline fluids in trans and rear diff.  Most FC's I've seen put between 14% and 16% friction loss on DynoJet 248x dynos.  I don't see where the 15% is that off.
Why don't we screw all the bullshit and strap the motors on an engine dyno and measure bhp?  Would that be good enough for you?
For example: how do you dyno a 300HP car on a 230 HP dyno? Easy. strap it down hard and get 3 people to sit on the back. This will increase losses to the point where you measure less than 230HP and then use a coast down to take out those losses
You talk bench racing. why don't you call mazdatrix and ask them what HP they are getting at 10K. The engine is built and dyno'd and raced, so therefore real in my book
-Ted
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From: Canada
I have a few questions...
1. Is it peak horsepower only you're after, or does usable power make a difference?
2. Do you have any real reason to outlaw a larger port size? Is it illegal in your racing class?
3. Are alternate fuels other than gasoline a possibility?
4. Are you willing to stray from the 6-port NA irons?
5. Are you willing to make a custom intake manifold?
6. How long are you expecting this engine to last?
1. Is it peak horsepower only you're after, or does usable power make a difference?
2. Do you have any real reason to outlaw a larger port size? Is it illegal in your racing class?
3. Are alternate fuels other than gasoline a possibility?
4. Are you willing to stray from the 6-port NA irons?
5. Are you willing to make a custom intake manifold?
6. How long are you expecting this engine to last?
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From: UK
Just a note to REted: You really know very little about dynos if all you go on is dynojets. Hope you ask to see the cal certificate next time you pay for one.
As for plain stupid, it isn't as the coast down calibrates it out.
It you bothered to look at the loss curve vs RPM off a calibrated dyno you would see that just quoting a percentage suggests a feeble grasp of what is actually going on when you use a chassis dyno. Then repeat with 10PSI more in the tyres and tell me 15% is accepted by any other than the stupid or the gullible.
As for plain stupid, it isn't as the coast down calibrates it out.
It you bothered to look at the loss curve vs RPM off a calibrated dyno you would see that just quoting a percentage suggests a feeble grasp of what is actually going on when you use a chassis dyno. Then repeat with 10PSI more in the tyres and tell me 15% is accepted by any other than the stupid or the gullible.
Joined: Feb 2001
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From: London, Ontario, Canada
Originally posted by bill Shurvinton
The stock intake, whatever you do will top out around 200HP area. IDA will get you in the 230 mark. After that you are getting into interesting territory. Port actuators will have to go, inlet length will become critical as will balance clearance and sealing. Things like ceramic seals will get you another 10lbft (source pineapple racing) and more RPM, but then you need to lighten things or go to a 2 piece eccentric.
The stock intake, whatever you do will top out around 200HP area. IDA will get you in the 230 mark. After that you are getting into interesting territory. Port actuators will have to go, inlet length will become critical as will balance clearance and sealing. Things like ceramic seals will get you another 10lbft (source pineapple racing) and more RPM, but then you need to lighten things or go to a 2 piece eccentric.
Oh yes get T2 rotor housings, better flowing exhaust and easier than grinding out the splitters.
Certainly a fun area to explore, especially as so few people have ever tried to push the 6-port.
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From: Canada
It would be possible to attach a set of plates to the dishes of the rotors, thus increasing compression. Attaching these would be complex at best... you could have them welded in, but there is always the worry of warping the rotor.
Of course, you would need to rebalance the rotor afterwards.
An issue that arises with this, though, is now a higher rotor mass which lowers the redline, and the oiling system (which cools the rotor) would require much development.
I am still wondering "why?" more than "how?"
Of course, you would need to rebalance the rotor afterwards.
An issue that arises with this, though, is now a higher rotor mass which lowers the redline, and the oiling system (which cools the rotor) would require much development.
I am still wondering "why?" more than "how?"
The mystery of the prize.
Joined: Aug 2002
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From: Bay area
Originally posted by Aaron Cake
There are no splitters in the TII exhaust ports.
There are no splitters in the TII exhaust ports.
For someone who is so argumentative on the forum and appears to be very opinionated, it's somewhat amusing to read such meaningless posts from you.
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From: UK
In my case that's easy. I have a 1200lb car. With the current 4-port I'll be around 400HP/ton. To get to the magic 500HP/ton mark will take around 270HP. Because of the light weight a turbo is not the best route as it compromises the handling too much, but a peaky NA is a very good option.
Sure I could go the bridge port route, but it would be interesting to push the limits of the 6-port in a non-bridge configuration first
Sure I could go the bridge port route, but it would be interesting to push the limits of the 6-port in a non-bridge configuration first
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From: n
Originally posted by bill Shurvinton
Just a note to REted: You really know very little about dynos if all you go on is dynojets. Hope you ask to see the cal certificate next time you pay for one.
As for plain stupid, it isn't as the coast down calibrates it out.
It you bothered to look at the loss curve vs RPM off a calibrated dyno you would see that just quoting a percentage suggests a feeble grasp of what is actually going on when you use a chassis dyno. Then repeat with 10PSI more in the tyres and tell me 15% is accepted by any other than the stupid or the gullible.
Just a note to REted: You really know very little about dynos if all you go on is dynojets. Hope you ask to see the cal certificate next time you pay for one.
As for plain stupid, it isn't as the coast down calibrates it out.
It you bothered to look at the loss curve vs RPM off a calibrated dyno you would see that just quoting a percentage suggests a feeble grasp of what is actually going on when you use a chassis dyno. Then repeat with 10PSI more in the tyres and tell me 15% is accepted by any other than the stupid or the gullible.
-Ted
Maybe I should read a page or two back, but doesn't the dyno jet come with it's own calibration?? Roller has X amount of weight, requires so much power to accelerate to X speed. How fast the car does this translates to torque which is then converted to HP by RPM???? Maybe I'm missing something.
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Joined: May 2001
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From: Conyngham, PA
Originally posted by rotarypwrd
FOR EVERYONE...........
Was doing an engine install tonight with some friends and am really thinking through the renesis rotors suggestion and how to make it work, how much more power it would generate w/o the rx8 exhaust ports. Also working through the idea of basically having an rx8 (renesis) motor (block), but swapping out the aluminum rotor housings w/ FD rotor housings (still having the old 2 exhaust ports). You'd now have 5 (technically 6) instead of 3 (technically 4) exhaust ports. What would that do to the motor? How would it change it's character of how it operates? What successes would there be w/ that configuration? What failures or setbacks or problems could there be w/ such a cofiguration (i.e. port timing, apex/corner seals falling out)? I know there would have to be a custom exhaust manifold (header) made, but what do all of my extended rotary family think of all that? Let me here your thoughts on this and any other ideas besides the ones I just mentioned. (remember constructive)
FOR EVERYONE...........
Was doing an engine install tonight with some friends and am really thinking through the renesis rotors suggestion and how to make it work, how much more power it would generate w/o the rx8 exhaust ports. Also working through the idea of basically having an rx8 (renesis) motor (block), but swapping out the aluminum rotor housings w/ FD rotor housings (still having the old 2 exhaust ports). You'd now have 5 (technically 6) instead of 3 (technically 4) exhaust ports. What would that do to the motor? How would it change it's character of how it operates? What successes would there be w/ that configuration? What failures or setbacks or problems could there be w/ such a cofiguration (i.e. port timing, apex/corner seals falling out)? I know there would have to be a custom exhaust manifold (header) made, but what do all of my extended rotary family think of all that? Let me here your thoughts on this and any other ideas besides the ones I just mentioned. (remember constructive)
Start with a renesis block. Remove the rotor housing and install FD housings. Effectivly giving you 6 exhaust ports and 6 intake ports? Yikes. I can't even imagine what the header flange would look like! (Assuming you could get it to seal...)
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From: UK
For those who believe that quoting a single %age is OK, here is an example off a UK eddy current dyno. This dyno is fully calibrated, and has been checked against engine dyno results with minimal errors. It is used by most of the club racing fraternity in the UK and is well trusted.
The flywheel figures have been calculated by adding back the coastdown figures to the wheel measurements. Taking 3 random RPM points and calculating the losses, with apologies for the odd numbers for RPM
RPM Wheel HP Flywheel HP %'loss'
5733 125 148 18
6741 149 180 20
7812 158 199 26
The spreadsheet is there if you wanted to calculate over the entire rev range. I can also get other runs for other cars as the operator keeps all dyno runs on file if you don't believe this one.
The simple point though is that losses are dependant on a number of factors, not least wheel speed. The faster you go the higher the relative losses. The more you have to strap the car down to stop it climbing out the rollers the higher the losses. The wider the tyres the higher the losses (hint, if you are going to a shoot out fit the narrowest tyres you can and pump them up to 40PSI).
The flywheel figures have been calculated by adding back the coastdown figures to the wheel measurements. Taking 3 random RPM points and calculating the losses, with apologies for the odd numbers for RPM
RPM Wheel HP Flywheel HP %'loss'
5733 125 148 18
6741 149 180 20
7812 158 199 26
The spreadsheet is there if you wanted to calculate over the entire rev range. I can also get other runs for other cars as the operator keeps all dyno runs on file if you don't believe this one.
The simple point though is that losses are dependant on a number of factors, not least wheel speed. The faster you go the higher the relative losses. The more you have to strap the car down to stop it climbing out the rollers the higher the losses. The wider the tyres the higher the losses (hint, if you are going to a shoot out fit the narrowest tyres you can and pump them up to 40PSI).
Senior Member
Joined: Apr 2003
Posts: 427
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From: UK
For those who believe that quoting a single %age is OK, here is an example off a UK eddy current dyno. This dyno is fully calibrated, and has been checked against engine dyno results with minimal errors. It is used by most of the club racing fraternity in the UK and is well trusted.
The flywheel figures have been calculated by adding back the coastdown figures to the wheel measurements. Taking 3 random RPM points and calculating the losses, with apologies for the odd numbers for RPM
RPM Wheel HP Flywheel HP %'loss'
5733 125 148 18
6741 149 180 20
7812 158 199 26
The spreadsheet is available if you wanted to calculate over the entire rev range. I can also get other runs for other cars as the operator keeps all dyno runs on file if you don't believe this one.
The simple point though is that losses are dependant on a number of factors, not least wheel speed. The faster you go the higher the relative losses. The more you have to strap the car down to stop it climbing out the rollers the higher the losses. The wider the tyres the higher the losses (hint, if you are going to a shoot out fit the narrowest tyres you can and pump them up to 40PSI).
The flywheel figures have been calculated by adding back the coastdown figures to the wheel measurements. Taking 3 random RPM points and calculating the losses, with apologies for the odd numbers for RPM
RPM Wheel HP Flywheel HP %'loss'
5733 125 148 18
6741 149 180 20
7812 158 199 26
The spreadsheet is available if you wanted to calculate over the entire rev range. I can also get other runs for other cars as the operator keeps all dyno runs on file if you don't believe this one.
The simple point though is that losses are dependant on a number of factors, not least wheel speed. The faster you go the higher the relative losses. The more you have to strap the car down to stop it climbing out the rollers the higher the losses. The wider the tyres the higher the losses (hint, if you are going to a shoot out fit the narrowest tyres you can and pump them up to 40PSI).
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
Originally posted by pengarufoo
Uhm, if you read what Bill typed, he's is saying the NA housings have sleeves and using the T2 rotor housings is easier than grinding out the sleeves from the NA housings.
For someone who is so argumentative on the forum and appears to be very opinionated, it's somewhat amusing to read such meaningless posts from you.
Uhm, if you read what Bill typed, he's is saying the NA housings have sleeves and using the T2 rotor housings is easier than grinding out the sleeves from the NA housings.
For someone who is so argumentative on the forum and appears to be very opinionated, it's somewhat amusing to read such meaningless posts from you.
I'm Naturally Aspirated
Joined: Aug 2003
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From: Cary, NC
Originally posted by ilike2eatricers
you could add light weight pullies and also do weight reduction. Numbers do not always tell all!
you could add light weight pullies and also do weight reduction. Numbers do not always tell all!
777** The Anti-rice
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From: Seattle, WA
Originally posted by Aaron Cake
Can't be done with just a streetport. You'd need a bridge or peripheral to get that high.
Can't be done with just a streetport. You'd need a bridge or peripheral to get that high.
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From: Alabama just east of B'ham
If you want to see a 2nd gen rx7 with 230-240HP to the rear tires watch the EProduction SCCA Runoffs on Speed this fall. The faster 2nd gen RX7's are making the HP numbers everyone is arguing about. They are not allowed to BPort or PPort and have to retain the factory intake manifold. Just massive street porting. They spend lots of money on the engines and spend lots of time on engine dyno's. Motec's are not uncommom on the starting grid.
These guys do what many of you dream about and many others say can't be done.
These guys do what many of you dream about and many others say can't be done.
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From: n
Originally posted by MPM
If you want to see a 2nd gen rx7 with 230-240HP to the rear tires watch the EProduction SCCA Runoffs on Speed this fall. The faster 2nd gen RX7's are making the HP numbers everyone is arguing about. They are not allowed to BPort or PPort and have to retain the factory intake manifold. Just massive street porting. They spend lots of money on the engines and spend lots of time on engine dyno's. Motec's are not uncommom on the starting grid.
These guys do what many of you dream about and many others say can't be done.
If you want to see a 2nd gen rx7 with 230-240HP to the rear tires watch the EProduction SCCA Runoffs on Speed this fall. The faster 2nd gen RX7's are making the HP numbers everyone is arguing about. They are not allowed to BPort or PPort and have to retain the factory intake manifold. Just massive street porting. They spend lots of money on the engines and spend lots of time on engine dyno's. Motec's are not uncommom on the starting grid.
These guys do what many of you dream about and many others say can't be done.
I know some of the top-running IT-S FC NA's on the east coast are rumored to run up to 220hp at the wheels (on stock ports!), so I dunno how these guys are running MORE than that? Advanced ignition timing on race gas?
-Ted
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