The 14b Drag Race Discussion Thread

[hubz91talontsi]

Yeah, you're correct. I have to agree. Terms are f'd and I'm fighting with myself. This whole thing was started by kiggly's car though. Pm me that same drag force table using .30 and .20. That would make me feel better Im just sure that more than 3mph will be gained at that speed.

 

[Nate Crisman]

Yeah, you're correct. I have to agree. Terms are f'd and I'm fighting with myself. This whole thing was started by kiggly's car though. Pm me that same drag force table using .30 and .20. That would make me feel better Im just sure that more than 3mph will be gained at that speed.

Im going to make a pretty heavy post most likely tonight regarding Aero. I'll calculate for hp loss for quite a few examples/speeds and hopefully show some interesting graphs. I'm hoping to boil it down to something meaningfull that we can all discuss with some actual data to back up our assumptions.

Also...Pneumo informed me by PM that the 5.82 number I was plugging into the calculator is incorrect, that's actually CdA (Coefficient of drag multiplied by Frontal Area). The quick google search I did unfortunately yealded an incorrectly labeled chart, so my innitial numbers are incorrect as the formula wants A for frontal area, not CdA. Actual frontal area of a 1G is more on the range of 20ft^2 not 5.81. So my innitial #'s are wrong....by how much....will find out soon.

Anyway, I'll have some time to make a spreadsheet tonight and hopefully be able to provide some better data that we can then carry on a productive discussion with.

 

[rrussell]

Great thread!!!

Heres the aero-calc I use.

Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

 

[9!'clipseDOHC]

Nice......oh yeah, gotta crush the BOV, I've been running mine crushed for about 12 years and it's a must. That should help for sure...good luck!

I crushed it last night and installed it this morning. I'm going to let the RTV set and then I'll do a BLT tomorrow after work. Before crushing it was opening at 15 inHG and now its opening at 20 inHg of vacuum. I hope this works!

You must be logged in to view this image or video.

Left is uncrushed, right is crushed.

 

[hubz91talontsi]

Good stuff nate. Im understand why people aren't concerned at aero at this level. Atleast we have some real numbers floating around. I will also state that in no way am i running for the real 14b record. So, i will step out of this thread and make my own when the time comes. Unless a billet 14b compressor wheel counts for anything. Also, phil was correct. The car is a twin turbo aluminum rod 2.3 10:1 motor. What i am trying to do is build a twin 14b setup that will spool around the same as a factory 14b car.

 

[Nate Crisman]

Good stuff nate. Im understand why people aren't concerned at aero at this level. Atleast we have some real numbers floating around. I will also state that in no way am i running for the real 14b record. So, i will step out of this thread and make my own when the time comes. Unless a billet 14b compressor wheel counts for anything. Also, phil was correct. The car is a twin turbo aluminum rod 2.3 10:1 motor. What i am trying to do is build a twin 14b setup that will spool around the same as a factory 14b car.

AHaha cool. I knew there had to be something crazy going on. Twin 14b's...ah hah. Well, that certainly doesn't count for the 14b record, but it's cool to hear none the less. I hope you have success with getting the car running and hope the engine setup makes all the power. It will definitely be one of a kind.

 

[hubz91talontsi]

Well, obviously two wouldnt count =D. What i ment was would one count? I could go dyno the car on my 2.0L with the billet 14b. I may anyways if anyone is interested in the extra flow of air and faster spool.

Also to clear any confusion.. When i said 10.9s on street tires i was referring to this setup, but its obviously miss leading.

Edit:

Actual frontal area of a 1G is more on the range of 20ft^2 not 5.81. So my innitial #'s are wrong....by how much....will find out soon.

So, the numbers will be more drastic than you first calculated?

 

[forcefed86]

Good stuff nate. Im understand why people aren't concerned at aero at this level. Atleast we have some real numbers floating around. I will also state that in no way am i running for the real 14b record. So, i will step out of this thread and make my own when the time comes. Unless a billet 14b compressor wheel counts for anything. Also, phil was correct. The car is a twin turbo aluminum rod 2.3 10:1 motor. What i am trying to do is build a twin 14b setup that will spool around the same as a factory 14b car.

Sounds fun!

I was toying with that idea and 2 e316g’s. I had a spare and was trying to mock up the spacing when I recently had my turbo out. If I wanted to keep all my accessories, ac, etc. Unless I placed them exh housing to exh housing and fabbed up a shared DP of some sort, . I just couldn’t find the room to mount both. Just a thought, but have you looked into the Twin turbo supra and rx-7 factory setups? The TT rx7 package fit in front of my DSM nicely. Would just have to make an adapter plate for the mani. Would be neat to have the sequential setup. Good luck, post tons of pics for us!

 

[pneumo]

rrussell posted an excellent link showing aero drag. Just type in a drag coefficient of .30 and frontal area of 20.05 and see what pops up in the table. Then change the Cd to .27 and see what happens. Look at the results in the column labeled 'HP aero'
At 120mph aero drag drops from 70.5hp to 63.5 hp, 7hp difference at the top end.
At 100mph drag drops from 40.8 to 36.8hp, 4hp difference.
At 75mph drag drops from 17.2 to 15.5hp, 1.7hp difference.
lower speeds have less savings.

I suppose if someone were going for the record this might make a slight difference, but at what cost? At the risk of repeating myself, I wouldn't recommend adding a belly pan since it can add significant weight and make the car a bi*** to work on. Good aero mods would be cheap and light, such as removing mirrors, remove wipers, raking the car so the nose is slightly lower than the front, block off the side bumper vents and lowering the car overall. I think that's the best of the cheap aero mods.

 

[Nate Crisman]

rrussell posted an excellent link showing aero drag. Just type in a drag coefficient of .30 and frontal area of 20.05 and see what pops up in the table. Then change the Cd to .27 and see what happens. Look at the results in the column labeled 'HP aero'
At 120mph aero drag drops from 70.5hp to 63.5 hp, 7hp difference at the top end.
At 100mph drag drops from 40.8 to 36.8hp, 4hp difference.
At 75mph drag drops from 17.2 to 15.5hp, 1.7hp difference.
lower speeds have less savings.

I suppose if someone were going for the record this might make a slight difference, but at what cost? At the risk of repeating myself, I wouldn't recommend adding a belly pan since it can add significant weight and make the car a bi*** to work on. Good aero mods would be cheap and light, such as removing mirrors, remove wipers, raking the car so the nose is slightly lower than the front, block off the side bumper vents and lowering the car overall. I think that's the best of the cheap aero mods.

I'll completely agree with Dave on his list of "easy" aero mods that also help the 60' and also remove weight at the same time. I just haven't had time to make a nice chart to compare curves and make a full analysis yet (my dodge durango everyday driver is having cooling issues, I gotta fix that first). But the fact remains, that the CHANGE in aero-drag-hp-loss by changing Cd from .30 to .27 is very small still. Still at most 7hp at 120mph, and 4hp at half track, which we can average to say that from the top half of the track the average loss is about 5.5hp.

Is 5hp going to make a giant difference in ET and only at the top of the track. It would make the same ET difference as launching and running 1-2-3 gears with nitrous off and spraying a HUGE 5hp nitrous shot at 1/8mile on....I would bet you'd barely see any ET difference, such a small change that you wouldn't know if it was from the aero or from normal run to run variance in shift point/air temp/launch/track condition. Maybe 1mph+ from 5hp only up top?

Going from .30 to .27 Cd might not even be in the range we are talking for basic aero mods (removing wipers, removing mirrors, blocking vents, rake & lower), reality might be that all those changes amount to .01Cd for all we know.

I'll still make the charts for posterity soon as my DD is fixed, but Im going to consider the Aero arguement case closed. Do the simply/easy stuff like Dave suggested above, but don't sweat the Fabrication heavy stuff like full front airdam, underside pans, and crazy wings/body mods until you have exhausted your potential to make another 5hp. When 5hp seems impossible to gain and the 60's are awesome, then start to think heavy Aero mods.

BUT another thing to consider is that as you change aero on the bottom/wing....the car might start to behave different at 120mph. One of the things the smart guys on NABR say is that the only Aero concern for drag racing is stability up top; that's when you need to start doing mods when the rear starts lifting at speed.

 

[hubz91talontsi]

Nate/Dave you also have to play with rolling resistance. It states on the bottom of that calculator that even .01-.019 are for smooth surface low friction tires. Slicks would be .02-.029. Not to mention that in no way is phil's car at .30cd. I'd say its around .34

 

[bullettdsm]

Good aero mods would be cheap and light, such as removing mirrors, remove wipers, raking the car so the nose is slightly lower than the front, block off the side bumper vents and lowering the car overall. I think that's the best of the cheap aero mods.

Bingo.

Im going to consider the Aero arguement case closed. Do the simply/easy stuff like Dave suggested above, but don't sweat the Fabrication heavy stuff.

Agreed.

MB

 

[Nate Crisman]

Nate/Dave you also have to play with rolling resistance. It states on the bottom of that calculator that even .01-.019 are for smooth surface low friction tires. Slicks would be .02-.029. Not to mention that in no way is phil's car at .30cd. I'd say its around .34

Rolling resistance is only going to change if your doing mods that increase downforce. The things we are talking about changing should have a negligible change in lift/downforce. The changes in rolling resistance that will make a significant difference are things that are likely counter productive. We don't want to alter Aero to produce more lift in order to squeek out 1hp of rolling resistance in the tradeoff that the car is unstable at speed and likely to crash. We don't want to run skinnier tires or less sticky rubber in order to save 1hp of rolling resistance at the expense of any traction on the launch.

Traction is ALWAY the MOST important thing, sacrificing traction for aero would be the stupidest choice you could make. Stability is also of way more importance than aero drag for obvious reasons. If anything, we should be doing mods that increase rolling resistance but would help the ET with more drag, more traction, more stability.

And what is the obsession with Phil's car's Aero condition? and where are you pulling .34 Cd out of? just a guess? That's one thing that we are completely guessing on....how much XXX modification affects .xx Cd. I know I'v searched around and haven't found out any real info on what degree of change one can make to Cd by changing things. For all we know Phil's "disaster of Aero" car is at .305 and our "ideal" mods for aero only drop a 1g down to .285. We really have no clue how much of a change in Cd we can make.

 

[hubz91talontsi]

And what is the obsession with Phil's car's Aero condition? and where are you pulling .34 Cd out of?

No obsession, but this topic was started with his car. Obviously im just guessing, but without the wing on the rear, and the bumper cut like that..

Traction is ALWAY the MOST important thing, sacrificing traction for aero would be the stupidest choice you could make.

I just mentioned this for people running street tires thats all.

We really have no clue how much of a change in Cd we can make.

You can calculate it.. In a test like i said prior. Most people time themselfs coasting down a hill.
http://www.instructables.com/id/Measure-the-drag-coefficient-of-your-car/

 

[Nate Crisman]

No obsession, but this topic was started with his car. Obviously im just guessing, but without the wing on the rear, and the bumper cut like that..



I just mentioned this for people running street tires thats all.



You can calculate it.. In a test like i said prior. Most people time themselfs coasting down a hill.
Measure the drag coefficient of your car

A: It would not surprise me to find out that the additional drag introduced by removing the wing is more than offset by the weight removed. Im saying that there might be more benefit in ET from dropping 10lb of wing and mounting hardware than is gained by the minor change in drag. The front bumper's change in Cd might be more than offset by better intercooler efficiency making more than the stated 5hp? I'v been saying it all along that sacrificing aero efficiency to make a gain in power,traction,weight is likely to be the better choice. The car might end up being faster for ET with the wing off and bumper cut because it is lighter and more powerful, even if slightly less aero efficient.

B: Street tires don't have a place in the discussion IMHO. I thought we were discussing the merits of aero modifications in respect chasing the 14b records, in which case, nothing but full drag slicks is going to get it done. Who cares about the rolling resistance of street tires when they can't get a decent 60'? That's exactly what Im talking about when we are arguing about moot points...street tires are completely irrelevant.

C: that calculation would be great to use if we had a streetcar 1g to test with that someone would give us back to back data after making the changes we are discussing. My 1g isn't street driveable, so I can't volunteer. It would be awesome to see the change in data going from "stock" exterior to Dave's list of basic easy DIY aero mods. -mirrors -wipers, blocked vents, raked & lowered.

Any Volunteer?

 

[DJ23GSX]

So, i will step out of this thread and make my own when the time comes. Unless a billet 14b compressor wheel counts for anything. Also, phil was correct. The car is a twin turbo aluminum rod 2.3 10:1 motor. What i am trying to do is build a twin 14b setup that will spool around the same as a factory 14b car.

I'm curious why your choosing to go with a twin 14b setup? You being into supra's you must know that about 95% (if not more ) of the high hp MKIV's ditch the twins for one big single turbo. I'm also curious how much more hp you think a second 14b will give you on a 4 cyl? Thats a serious question no joking. I remember years ago someone attempting a twin 16g 1g dsm and he had all kinds of trouble getting the second turbo to spool before 7k rpms. I mean 14b's are cheap enough and there are some pretty nutty guys on here but its not very often you see a twin turbo dsm and it leads me to believe it just might not be worth it . When you make your own thread and this project gets off the ground post up a link and I'd better see lots of pics

 

[hubz91talontsi]

Nahh, we can't clutter this up with my car. If you have a question about my car pm me.

 

[DJ23GSX]

Nahh, we can't clutter this up with my car. If you have a question about my car pm me.

Fair enough

 

[91stocker]

B: Street tires don't have a place in the discussion IMHO. I thought we were discussing the merits of aero modifications in respect chasing the 14b records, in which case, nothing but full drag slicks is going to get it done. Who cares about the rolling resistance of street tires when they can't get a decent 60'? That's exactly what Im talking about when we are arguing about moot points...street tires are completely irrelevant.

Im sorry but who says you cant get decent 60' of street tires. RWD camaro/stangs can cut 1.5-1.6's on streets. You awd guys on slicks are barely getting that. What some people noticed at shootout this last year was that they were able to pull better 60's on streets because of the quality prep on the track. I guess if your running on a sidewalk track streets might not cut, but even then awd idk.

 

[Nate Crisman]

Im sorry but who says you cant get decent 60' of street tires. RWD camaro/stangs can cut 1.5-1.6's on streets. You awd guys on slicks are barely getting that. What some people noticed at shootout this last year was that they were able to pull better 60's on streets because of the quality prep on the track. I guess if your running on a sidewalk track streets might not cut, but even then awd idk.

I consider 1.5's on the weak side, 1.4's are good, and high 1.3's the goal. Go look at Phil's car and Pneumo's last 16g slips. My car went 1.4's a few times on the first time out without any launch fine tuning. If anyone wants to challenge the 14b records, it's flat out not going to happen on regular street tires with a high 1.5 or 1.6 launch, that's just not good enough anymore. It's going to take a bottom 1.4 if not a 1.375 which is way beyond the realm of radials.

In the end it doesn't matter if you can get a "decent" 60' on street tires, because you can always get a better 60' with full slicks.

Point was that street tires are so much more of a handycap than any aero disadvantage ever could be. All the aero mods possible don't even come close to the difference between a 1.6 and a 1.4 launch. Therefor if you aren't running on full slicks yet, it's a waste of time to worry about aero when your giving up .400 or more of ET in traction.

 

[hubz91talontsi]

Joe ran high 1.5's.. Did he not?

 

[Nate Crisman]

Joe ran high 1.5's.. Did he not?

1.579 on the 16g record and 1.62 on the 14b record. He might have been up/down from there a bit but that seems to be pretty healthy for FWD on slicks. Hence why I say it's going to take a 1.4 from an awd car to make up for the weight disadvantage and rear drivetrain loss. (assuming equal power, and frankly, the power is the real equalizer in 14b racing as there's only so many tricks to pull for power)

 

[91stocker]

(assuming equal power, and frankly, the power is the real equalizer in 14b racing as there's only so many tricks to pull for power)

Thats why i find this thread and the 14b records so interesting.

 

[Phil1320]

Im sorry but who says you cant get decent 60' of street tires. RWD camaro/stangs can cut 1.5-1.6's on streets. You awd guys on slicks are barely getting that. What some people noticed at shootout this last year was that they were able to pull better 60's on streets because of the quality prep on the track. I guess if your running on a sidewalk track streets might not cut, but even then awd idk.

A decent 60' on street tires is a low 1.7 range....a good 60' on street tires is low-mid 1.6, my best was a 1.65 and I averaged 1.71-1.72.

At my last track outing in 5 passes my 60' times were 1.48-1.50. So, my "Slow" 60' was a 1.50. That's gettin the job done as far as I'm concerned. Camaro/Mustang have no relevance here. Different drivetrain entirely.

Track prep is key. Car setup is a factor as well. If I bolt my 16" wheels with drag radials back on the car....I will light all four tires all the way through first gear producing 60' times between 1.8-2.0, light all four tires all the way through second gear.......then light the front tires off in 3rd gear producing 12.0-12.2 ET's.

As far as I know my 1.480 is the quickest 14b AWD 60' time to date. There is more left. It's not that I wanted to "try" slicks out. I needed them with my car's weight and super stiff suspension....and so far it's working well.

I consider 1.5's on the weak side, 1.4's are good, and high 1.3's the goal. Go look at Phil's car and Pneumo's last 16g slips. My car went 1.4's a few times on the first time out without any launch fine tuning. If anyone wants to challenge the 14b records, it's flat out not going to happen on regular street tires with a high 1.5 or 1.6 launch, that's just not good enough anymore. It's going to take a bottom 1.4 if not a 1.375 which is way beyond the realm of radials.

In the end it doesn't matter if you can get a "decent" 60' on street tires, because you can always get a better 60' with full slicks.

Point was that street tires are so much more of a handycap than any aero disadvantage ever could be. All the aero mods possible don't even come close to the difference between a 1.6 and a 1.4 launch. Therefor if you aren't running on full slicks yet, it's a waste of time to worry about aero when your giving up .400 or more of ET in traction.

Agreed. 1.6 isn't gonna get it done.......and on all points.

I'm honestly thinking I've got .15 seconds left to the 60' up for grabs for a best case scenario of 1.33-1.35 max potential.......

.....I've removed the middle portion of my rear wing and feel that the weight reduction from that is a far greater assett to my ET than the potential addition of drag created by removing it.

Joe ran high 1.5's.. Did he not?

Nate has listed Joe's 60' on his record runs above...however I think his best all time 60' time was 1.52 or so. I'm pretty certain he did not touch the land of the 1.40's....

 

[Kevin Jewer]

Well, that was a long read. A few things come to mind.

-60 foot times will have a limit based on your power and weight, which limits your potential acceleration. Even with 100% perfect traction, 60 foot times can't be infinitely low. I'd be surprised if anyone could get into the 1.3s at all with a 14b or a 16g. I suspect the limit is somewhere in the 1.4s. If you're anywhere near there, or anywhere in the 1.5s, I'd focus your efforts elsewhere. Good 60 foot times for street tires are in the low 1.6s IMO. I ran 1.55-1.65 short times on street tires for many years with turbos of this size. If you're in that range and not within 2 tenths of the record, I wouldn't bother spending a small fortune to get that last tenth off the 60.

-The larger turbine housing should definitely help power, even though the compressor is small. I'd bet the terminal intake to exhaust pressure ratio still gets to at least 2:1 maxed out. I never did a back to back test with the 6 and 7cm housings for power or track times (I did see a 200 degree drop in EGTs though), but in no case is higher drive pressure a desireable thing... As long as the turbo still spools in time and enough exhaust energy can be extracted to drive the compressor to the output you need, bigger is better IMO. I have the 10cm T3 housing, and I'm setup to log drive pressure, so if someone could share drive pressure on 6cm and 7cm housings we could compare after I get around to making some runs.

-In the case with nitrous, the turbine wheel/housing is only the limiting factor if you are not using the wastegate. If boost is set to a controllable level (not maxed out and tapering boost), any additional exhaust product that the nitrous provides will be wastegated. If the WG can't pass it, you'll see it as boost creep. The only exhaust that goes through the turbine is what is needed to provide the turbine power required to make the boost you're set for. For nitrous, I'd recommend setting boost to just below what the turbo can hold and let the nitrous do the rest. Logging drive pressure will show you what the best compromise will be.

-I agree that aerodynamics are mostly a non issue in drag racing. The part of the race that matters most is the part where you are barely even moving. The drag race is won in the 60 foot, as we often say. By the time aerodynamics matter, the ET is already in the bag. Mile racing is completely different.

I have a 14b and big 16g, and that T3 housing, so I would like to put them on either the RWD or the Mighty Max (or both) this year to see what they can do. The RWD will be a max effort setup, and probably the closest thing to Joe Bucci's setup yet in this pursuit. Power loss in the drivetrain will be the only downside (though autos still ET well none the less). The Mighty Max is similar but "full weight," whatever that is (haven't had it on a scale). RWD with drag radials and a three speed automatic, and a 2.3 liter. I might skip over the 14b. I was shooting 14b turbine wheels out the exhaust 9 years ago, I'm not sure I want to go back to that. Most people won't care much what they run as far as the record goes, but it will be interesting to see what happens.