69 replies to this topic

[38bfast]

Eric could you email me your .drk files with and without the plate.

[Erik Hardy]

Yea, Around lunch I can post a picture as well. 

[speedengineer]

Keep in mind, you're looking at hp changes of the order of magnitude that affect top speed by about 1 mph.  Ambient temperature, humidity, baro, headwind, a draft, and other variables can all have a much larger influence than 1mph on vehicle performance on the straights.  Makes drawing any meaningful conclusions from empirical data rather difficult...

[Erik Hardy]

White lines are with 47mm restrictor, Pinky lines are without. I believe the STL race was 2 races after the SM race. The data might look like a bunch of squiggles because yea its only 3hp....but look at the top speeds. Both races had various car battles with occasional draft but the top speeds are apparent.

 

With Restrictor:

111.6

111.3

111.5

111.7

111.1

111.4

Average 111.4

 

Full Horsepower mode:

112.7

112.1

113.3

112.7

112.0

112.4

Average 112.5

 

If you look back on Jason's build thread with his lap sim results for Mid-Ohio he concluded 1mph = 3hp. I witnessed a drop in 3hp at the dyno and on average I saw a 1mph delta at Mid-ohio on the back straight. Science bitches

 

[Tom Sager]

Ralph and others, There was a time, a very long time, when SCCA made competition adjustments to cars that were raced in very small numbers and no data was available except for entries, results, the view from the windshield and the rear view mirror and possibly some video.  Somehow the club made that work.  It only took the will and common sense of the committee. 

 

As for restrictor plates for the NA 1.8, my '95 picks up about 3.0-4.0 HP through much of the range comparing 47mm to no plate as best I can recall but it has been a few years since measuring that.  I believe that would be too much of an increase in power, but at equal weight to the '99 it would be slightly handicapped by old geometry suspension.  Then at 125 pounds heavier than a 1.6 with the same suspension it may be a pig to drive in comparison. 

 

For me this isn't complicated.  The car needs help but only a little.  As long as it has the older suspension it needs to be lighter and weigh close to the 1.6. If I were king for a day I'd take 25 pounds off the NA 1.8 and leave the plate alone or give it a 49mm plate and leave the weight alone.  Then I'd watch the entries and results knowing that another tweak in one direction or the other is only a month away. 

[Jim Drago]

Ralph and others, There was a time, a very long time, when SCCA made competition adjustments to cars that were raced in very small numbers and no data was available except for entries, results, the view from the windshield and the rear view mirror and possibly some video.  Somehow the club made that work.  It only took the will and common sense of the committee. 

 

As for restrictor plates for the NA 1.8, my '95 picks up about 3.0-4.0 HP through much of the range comparing 47mm to no plate as best I can recall but it has been a few years since measuring that.  I believe that would be too much of an increase in power, but at equal weight to the '99 it would be slightly handicapped by old geometry suspension.  Then at 125 pounds heavier than a 1.6 with the same suspension it may be a pig to drive in comparison. 

 

For me this isn't complicated.  The car needs help but only a little.  As long as it has the older suspension it needs to be lighter and weigh close to the 1.6. If I were king for a day I'd take 25 pounds off the NA 1.8 and leave the plate alone or give it a 49mm plate and leave the weight alone.  Then I'd watch the entries and results knowing that another tweak in one direction or the other is only a month away. 

While I agree with the logic and ideas on changes.. I disagree with the entries meaning much of anything in regard to the change being correct, especially with a change this small. No one is staying home bc of a 25 lbs,  No way.

[CarbonRacer]

Tom,

 

Your dyno numbers don't seem to match mine and others I have talked to including engine builders. What I have tested and others have told me is the difference between 47mm plate and no plate is 1 - 2 HP.

 

I have built two different 1997 NA cars and they are difficult to make weight when you are a large driver. When I say large driver I don't mean beer gut large, I played football and I workout some so for me to get below my current 230 lbs. driver weight with no racing gear it would be very difficult. I mainly race in Florida and as you know it is very hot in the summer and for the past 6 yrs. of racing I have not been able to use a Cool Suit because my car would be way over weight. If they lower the weight for the NA 1.8 I will have to race either with no doors or cut half of the roll cage out of the car. ;-) 

 

It has been about 1 year since the plate change from 45mm to 47mm and I don't know any NA 1.8 that has won a race in the Southeast against an NB car. If someone knows of any NA 1.8 across the country that has won a race in the last year since the plate change against a decent NB car I would like to know how many.

[Jim Drago]

Tom,
 
Your dyno numbers don't seem to match mine and others I have talked to including engine builders. What I have tested and others have told me is the difference between 47mm plate and no plate is 1 - 2 HP.

I think you might want to check that again.. 45 to 47 was about 1.25-1.50 hp, I think throttle body is 54mm? I havent tested in years, but my numbers seemed closer to Toms

[Tom Sager]

Tom,

 

Your dyno numbers don't seem to match mine and others I have talked to including engine builders. What I have tested and others have told me is the difference between 47mm plate and no plate is 1 - 2 HP.

 

I have built two different 1997 NA cars and they are difficult to make weight when you are a large driver. When I say large driver I don't mean beer gut large, I played football and I workout some so for me to get below my current 230 lbs. driver weight with no racing gear it would be very difficult. I mainly race in Florida and as you know it is very hot in the summer and for the past 6 yrs. of racing I have not been able to use a Cool Suit because my car would be way over weight. If they lower the weight for the NA 1.8 I will have to race either with no doors or cut half of the roll cage out of the car. ;-) 

 

It has been about 1 year since the plate change from 45mm to 47mm and I don't know any NA 1.8 that has won a race in the Southeast against an NB car. If someone knows of any NA 1.8 across the country that has won a race in the last year since the plate change against a decent NB car I would like to know how many.

 

My '95 before we added some things was under 2100 without driver and ballast.  I think Mike Collins posted that he has seen NA1.8's at 2050 but cage design and other choices can add weight so some may weigh more.  While I don't have the dyno plots handy (47mm vs no RP) I'm confident that the gain is at least 3+ HP without RP for 2 different engines that we had built.  If someone were to pull the plate only and not tune a bit then the increase might be a bit less and I suppose there can be some variance from one engine to the next.

 

Regarding Jim's comment I agree people aren't staying home for 25 pounds but the abandonment of these cars for others and that nobody (or almost nobody) that's serious about winning is building them says a lot.  NA1.8 owners can easily make their cars quite competitive within the existing rules by selling them and adding about $15K to the proceeds to get a well prepped NB.  $40 though buys a newer larger plate and requires a lot less time and effort than the $15K solution.  

[Sean - MiataCage]

If someone knows of any NA 1.8 across the country that has won a race in the last year since the plate change against a decent NB car I would like to know how many.

 

Mark Drennan has won many, many races up and down the West Coast in his 94 and Matt Schultz finished P2 at the 14 Runoffs in his NA 1.8l.  If I recall correctly Mark owned 2 NB's (one VVT) in 2014 as well and seemed to only need the 94 to dominate.

 

Here are few track records for N California tracks....

 

Sears Point Qualifying Track Record - Mark Drennan 94 - 7/6/2014 - 1:53.832

Sears Point Race Track Record - Mark Drennan 94 - 7/6/2014 - 1:54.933

Thunder hill  Qualifying Track Record - Mark Drennan 94 - 3/8/2014 - 2:07.085  This held from 2008 through April of 2014 and was then broke by Charlie Hayes in April of 2014

Laguna Qualifying Track Record - Mark Drennan 94 - 6/8/2014 - 1:45.152

Laguna Race Track Record - Mark Drennan 94 - 6/7/2014 - 1:45.457

 

Where is the Mic Drop emoji?  

 

It is my opinion that a well built NA 1.8L with a great driver can do very well under the current rules package. 

 

[CarbonRacer]

Sean - MiataCage,

 

Congratulations to Mark Drennan for all of his track records. I'm curious about a couple things though and maybe you can shed some light on it.

 

Mark Drennan set two tracks records with his 94 NA 1.8 at Laguna in June 2014, why did he run a NB for the 2014 Runoffs at Laguna a couple months later? Doesn't make sense to me that he didn't run the car that he just set two track records.

 

Matt Schultz finished 2nd Position in his NA 1.8 in the 2014 Runoffs is correct  BUT  he was moved up to that position because the first 6 NB's in front of him were disqualified or sent to the back of the field.

 

Also, Matt Schultz NA 1.8 finished 37.939 seconds behind the leader at the finish.

 

If a well built NA 1.8 with a great driver will do very well under the current rules package, why wasn't any raced at the 2015 Runoffs at Daytona after the rule change to the 47mm plate?

 

 

Mic Drop Emoji     

[CarbonRacer]

I think you might want to check that again.. 45 to 47 was about 1.25-1.50 hp, I think throttle body is 54mm? I havent tested in years, but my numbers seemed closer to Toms

 

I just want to run some numbers.

 

The Throttle Body is 54mm in the center at it's smallest point.

 

45mm to 47mm was about 1.25 HP - 1.50 HP = .625 HP to .75 HP per mm larger opening on the restrictor plate in theory.

 

47mm to 54mm (No Plate) Throttle Body = 4.375 HP to 5.25 HP increase with no plate in theory using calculations from above. Nobody is getting 4 - 5 HP increase by pulling the plate.

[Erik Hardy]

Don't use linear interpolations (diameter) to get an understanding of flow area (pi * d^2 / 4) and measured engine performance. I have the dyno graph at home that shows a 3hp delta. 

 

 

47mm to 54mm (No Plate) Throttle Body = 4.375 HP to 5.25 HP increase with no plate in theory using calculations from above. 

[speedengineer]

[CarbonRacer]

Don't use linear interpolations (diameter) to get an understanding of flow area (pi * d^2 / 4) and measured engine performance. I have the dyno graph at home that shows a 3hp delta. 

 

I understand that linear interpolations is not the same as flow area that is why I put in the statement it is theory for a quick calculation as an example.

 

Also, in SpeedEngineer's graph for the 99 (Simulated) it shows going from a 46mm plate to No Plate on the 99 NB is less than a 2 HP increase as an example.

 

I'm not trying to say that your dyno is off or your 3 HP Delta is off I was just trying to show examples for discussions.

[Tom Sager]

Mark Drennan has won many, many races up and down the West Coast in his 94 and Matt Schultz finished P2 at the 14 Runoffs in his NA 1.8l.  If I recall correctly Mark owned 2 NB's (one VVT) in 2014 as well and seemed to only need the 94 to dominate.

 

Here are few track records for N California tracks....

 

Sears Point Qualifying Track Record - Mark Drennan 94 - 7/6/2014 - 1:53.832

Sears Point Race Track Record - Mark Drennan 94 - 7/6/2014 - 1:54.933

Thunder hill  Qualifying Track Record - Mark Drennan 94 - 3/8/2014 - 2:07.085  This held from 2008 through April of 2014 and was then broke by Charlie Hayes in April of 2014

Laguna Qualifying Track Record - Mark Drennan 94 - 6/8/2014 - 1:45.152

Laguna Race Track Record - Mark Drennan 94 - 6/7/2014 - 1:45.457

 

Where is the Mic Drop emoji?  

 

It is my opinion that a well built NA 1.8L with a great driver can do very well under the current rules package. 

 

Yes very well but can the same great driver or a group of great drivers do equally well in an NA 1.8 as they can in an NB at a variety of tracks against other great competition over the course of a season?  The abandonment of the cars by very good drivers all over the country over the past few years says no.  The results of the best contested races say no.  The choice of car by racers says no.  All of these data points are more important and more weighty than dyno plots, data files from one car or one weekend and opinions.  Although, dyno plots and data files are useful in the argument.

[speedengineer]

I'm not convinced that the argument of "people aren't racing/building them, thus they're not competitive cars" is valid.  It might be, might not.  That whole correlation/causation catch.

 

There are other reasons for people's choice of car to race.  I know that personally, I had no interest in building a NA car.  I don't like them.  They are getting rather dated looking, more difficult to find clean donor cars and parts.  Etc. 

[Jim Drago]

I just want to run some numbers.

 

The Throttle Body is 54mm in the center at it's smallest point.

 

45mm to 47mm was about 1.25 HP - 1.50 HP = .625 HP to .75 HP per mm larger opening on the restrictor plate in theory.

 

47mm to 54mm (No Plate) Throttle Body = 4.375 HP to 5.25 HP increase with no plate in theory using calculations from above. Nobody is getting 4 - 5 HP increase by pulling the plate.

What has been said above and my guess would be 3.5 Plus

If need be and asked , I can test I have a car here

[Bench Racer]

The choice of NA or NB, it's all about the sensual eyes the NB's have.

 

Jason, back to the shop and continue to play this song for a reminder.

 

 

The race track is wait-in for you.

[Danica Davison]

 

 

It has been about 1 year since the plate change from 45mm to 47mm and I don't know any NA 1.8 that has won a race in the Southeast against an NB car. If someone knows of any NA 1.8 across the country that has won a race in the last year since the plate change against a decent NB car I would like to know how many.

 

Nick Jeffs '96 car has finished top 2 in Daytona almost every race weekend in the last couple years.