F20/D20/F28 Revisited

Post by **PrecisionBoost** » Thu Feb 28, 2008 1:19 am

Thanks for not taking offence...I'm just really really confused by these numbers.... and thanks for the dyno graph......I still think there is something off here...perhaps it's the dyno.

I'm not trying to knock your setup.... I just think that the reason your D20 is holding up is because the power levels measured on the dyno are not correct.

Your running 261hp at the wheels with 2976lbs at 14.2s ........... My MS3 is running 233hp (28whp less) at the wheels with 3790lbs (814lbs more) at 14.3s

Hopefully you see why I'm confused.

If my MS3 had 28hp more power (equal with yours) I should drop my ET by roughly 0.5 s and run a 13.8s 1/4 mile ( which is consistent with current MS3 drag slip times )

Dropping the 800lbs should drop that down in around 13 s

I'm really sort of confused.... so the 335hp and 296 lbft up top is way more than the 261hp/239lb-ft you said you found on the latest dyno..... so were you estimating the 335hp as the crank horsepower?

I'm also confused as to why you made 305hp/293 lb-ft on your old dyno before upgrading your intercooler and injectors and now it's only 261hp/239lb-ft

Hmmm... your trap speed seems high for a 14.2 ET

With the new weight numbers 205whp should give a 14.2s 1/4 mile at 96 MPH

If you ignore the ET and just do it on trap speed it's more like 235whp

I'm not making this up..... I'm using a couple of reliable and proven " HP/WEIGHT/ET/TRAP" calculators..... and they all come up with these same numbers.

So..... I still don't see your vehicle creating enough power to damage the D20..... I'm sure your getting close.... but I still think your in around 200whp to 235whp.

Post by **PrecisionBoost** » Thu Feb 28, 2008 1:26 am

1)) Opel TS 6 speed gearbox with LSD
2) Button clutch - 3 puck
3) Opel TS side shafts
4) Uprated engine mounts and control arm bushes
5) Uprated brakes
6) ???????

Sounds like a good plan..... perhaps you might want to think about an electronic boost controller that will allow you to change boost versus speed.

That way you can run lower boost in the first two or three gears and then up the boost.

The "GSi Turbo" spins summer tires up into 4th gear.... then it grabs and goes like hell.... it will be seeing an F28 with LSD sometime later this summer.

Nubaroo · Post by **Nubaroo** » Thu Feb 28, 2008 4:37 am

Cool it sounds good

The old figures were crancshaft power on the dyno by Viper, and the new figures quoted is wheelpower taken on another dyno by another speed shop - maybe the dyno`s here in SA is just a bit optimistic....LOL!
Thats why the figures are lower than the old ones

I think to run in the 12`s you need about 400KW wheel power as you see in the articel I posted on the Opel TS - most of the cars quoted in the speed magazine running 11 and 12 seconds quote 380+ KW on the wheels and ALL the opels are running F28 boxes with LSD.

Here by us the Opel OPC`s and Ford Fucus ST`s all run around 15.5 to 15.8 seconds on the 1/4 miles and they are round 165 to 179KW on the crankshaft. The Subaru WRX STI`s run round 14.8seconds because they are 4wheel drive - off course that explains my surprise when the Scooby I raced recently ran a 13.3sec and kicked my butt....LOL That is why I am "happy" with a 14.2 seconds on mine.
Thanks for the input - my car is going on another dyno soon for fine tuning, it will be interresting to compare the numbers with the other 2 x dyno results.

exist3nce · Post by **exist3nce** » Thu Feb 28, 2008 5:00 am

Nubaroo wrote: The Subaru WRX STI`s run round 14.8seconds because they are 4wheel drive - off course that explains my surprise when the Scooby I raced recently ran a 13.3sec and kicked my butt....LOL

Wow 14.8 ?! Here and in the USA the STI is easily good for 13's stock each and every day.

Nubaroo · Post by **Nubaroo** » Thu Feb 28, 2008 8:02 pm

I am just waiting for our local speed and sound magazine to come out then I will scan and post some of the times all the different classes run - should make for interesting reading.

Regards to all

Post by **PrecisionBoost** » Fri Feb 29, 2008 12:15 am

Hmmmmmmm..... this is going to sound odd... but how long is a 1/4 mile track in SA (preferably in meters) ??

The reason I ask is because your quoting high numbers for ET and high numbers for trap speed.

If for some odd reason the 1/4mile track was slightly longer in SA that would make this all make sense. ( since your ET would be a bigger number as well as trap speed if you had to travel an extra 100 feet or something like that )

here is a great site for comparison....

http://www.dragtimes.com/browse.php

The absolute worst STi time I found was 13.885.... completely stock

here is a stock STi running 13.073 ..... http://www.dragtimes.com/Subaru-Impreza ... -2874.html

here is one of the guys from our board ( Nubira 2.2 ) running his 1998 Daewoo Nubira with 147whp @4psi (0.27 Bar)..... he ran a 14.763 @ 93.9 MPH

The slip is dated march 1,2007 ..... here is his project http://www.daewootech.com/forum/viewtopic.php?t=8149

Now he's running 13psi and he's making 217Whp and 204 lb ft........ and remember he's running the 2.2L not the 2.0L

So I still don't know what to say..... honestly I'm just trying to get to the bottom of this.... I still peg your car in around the same figure of 200whp.

If I were to make an educated guess I'd say Nubira 2.2 will run 13.95s @98 MPH with his current configuration.

Like I said before...... your trap speed is way higher than I would expect...... what else can be the problem.

Hmmmm..... what about heat..... what kind of temperatures are you running when you did your 1/4 mile???

Heat could suck the power out of the car and make the 1/4 ET significantly higher.

Post by **Efratech** » Fri Feb 29, 2008 12:54 am

i think he meant a stock WRX, not an STI

do you run at Tarlton?

whats your 60 ft mate?

Nubaroo · Post by **Nubaroo** » Fri Feb 29, 2008 5:58 pm

Here in SA the track temperatures during summer is normally around 26 to 28 degrees celsius, and the altitude is +- 1650meters above sea level. The "track" I am running on is a air landing strip that we borrow once a month from the airfield - so it`s not a prepared track with lots of "bite" at the lines like most propper race tracks???

We run races on a 400meter track which is 2.336meters shorter than the 1/4 mile.....!

My car`s power reading have been compared on 2 x different dyno`s and they were +- 5KW within each other`s readings.

Post by **PrecisionBoost** » Sat Mar 01, 2008 5:52 pm

Ah..... ok..... that explains it..... if your running on an airfield that would probably make a difference on the 60ft times..... which would explain the slow ET with higher trap speed.

I've been under the assumption all the way along that your on a properly prepared drag strip of some sort..... for which the ET/HP/Trap/Weight calculators work very well.

26 to 28 is pretty reasonable temperature wise..... for some reason I thought SA would have been hotter than that.

I have to think that wheelspin is your saviour...... a hard launch with semi slicks on a sticky prepared drag strip might end the life of your gearbox.... but it should be fine for street with the current power levels (based upon dyno information).

Your powerband is fairly narrow in the sense that it really doesn't start to make siginificant numbers until well after 4000 RPM.

According to your Dynograph you made a peak torque of 320 Nm which is 236 lb ft ..... and it comes in at 5107 RPM

The "GSi Turbo" project car currently makes 255.54 lb ft ( 346.5 Nm ) at 3800 RPM and it's running the F20.... which is the older European predicessor to the D20.

Most belive the F20 is stronger than the D20..... but there has never been any solid proof of that.

So your applying that peak level of torque only for a fraction of a second before shifting.... so that would be less harmfull than applying that high level torque over a long period of time ( say 3500 RPM to 6000 RPM )

Think of it like someone twisting your arm.... if it's a very quick jerk it hurts but nothing comes of it.....if however someone jerks it and holds that twist on your arm for three or four seconds they might end up ripping tissue.

So the way I see it based upon your dynograph you are only making perhaps 20% more than the accepted handling power of the gearbox.

The F28 should technically be only good for 280 lbft but there are lots of guys running 350 lbft on a regular basis in the UK.

If we take that into consideration then we can perhaps say that the F20/D20 maximum torque rating should be around 260 lb ft.

Also keep in mind that your soft engine mounts are absorbing quite a bit of the initial first gear launch.... if you put in solid mounts you may find that it will transfer more initial torque to the D20 and snap the input shaft.

What I'm saying is that wheelspin and soft mounts absorb quite a bit of the initial torque shock during launch..... and your turbo isn't spooled at 4000 RPM (since your not under load) so you might only be putting down 100 lbft of torque during your initial launch.

I'm not sure what your boost gauge reads during your 4K launches.... but I have to think it's not 13psi.... unless you have an anti-lag system.

Personally..... I think the place you will break the gearbox is on the 1-2 shift ( which I assume you do near redline ) where your turbo is spooled up and your making roughly 200lbft of torque going into 2nd gear.

Everything is just an "educated guess"..... when it comes right down to it each gearbox of the same type will have a slightly different torque handling limit since the materials are not perfect..... they aren't making for racing.... they are simply making them for everyday driving.

I'm sure that when the manufacturer tests the gearboxes they break a few dozen gearboxes and take the "worst case" which is the one that broke at the lowest torque... then they apply an engineering formula for statistical risk and derate the gearbox even further.

So lets say they broke one D20 at 220 lb ft..... well then they might rate the entire series for 200 lbft knowing that statisticly only one or two percent of the gearboxes will structurally fail at less than 200lbft.

They aren't going to break 2000 gearboxes to get a really good solid capacity number.... they are only going to break enough to make a nice statistical model for the gearbox group.

Now.... some of those gearboxes might take 330 lbft before they break.... who knows..... all they are concerned with is what percentage of gearboxes will come back on warranty due to material defects.

If they accept a 1 to 2 percent warranty return then the engineering forumla will statisticly predict the "official rating"

So who knows...... your D20 might be good for 22psi...... there is no way to know for sure.

Nubira2.2 · Post by **Nubira2.2** » Sat Mar 01, 2008 6:15 pm

PrecisionBoost wrote:If I were to make an educated guess I'd say Nubira 2.2 will run 13.95s @98 MPH with his current configuration.

first time i read in this post is very interesting

when my car did 14.7 @ 93.9 mph

was @ 4psi and auto tranny

last time i took the car to the track before the new numbers

the car did 14.7 @ 98 mph manual tranny and 8psi, doing bad 60' and slower 1/8 mile that in the previous 14.7 run with auto tranny

now i spec to be doing mid 13's if everything else is perfect

bad thing is that since i did the swap i have no speedometer

Post by **PrecisionBoost** » Sat Mar 01, 2008 7:32 pm

Which transmission did you put into your Nubira?

I forgot you had an automatic.... that might help your times a bit.....but I still think mid 13's would be a bit on the optimistic side.

Your going to start to have to fight for traction now..... you won't be able to apply all of your new found power/torque.... that's why I figured you would be high 13's

If you had a limited slip that would help a great deal..... if you had slicks that would also help a great deal (of course you run the risk of breaking things with the slicks )

Nubaroo · Post by **Nubaroo** » Sat Mar 01, 2008 8:36 pm

Thanks for all the info - it really makes sense from what you have explained - the soft engine mounts and control arm bushes cusshioning the peak surge to the gearbox. Also with the T3/T4 turbo spooling up slower ( I dont have ALS) I must admit that I have not seen the boost past 0.6 BAR in first gear ...?? I have been told by many guys that I have raced against that my car packs a MEAN 2nd gear - probably because I then only have FULL boost. I think this is a good thing helping with pull off ( limitimg wheel spin) and preventing breaking things LOL. This is something to check. Will record a nice video clip tomorrow and analise and maybe even post??? Thanks again.

Nubira2.2 · Post by **Nubira2.2** » Sun Mar 02, 2008 12:10 am

well i ran in the street with a 85 honda crx with a JDM B16A that does constant 14.0 @ 100 - 101 mph
in fourth gear i'm one and half car ahead

i think is from a nubira hydrulic clutch F20 i think

gse_turbo · Post by **gse_turbo** » Tue Mar 11, 2008 11:24 pm

This might have been gone over before, if so point me in the direction, but the imput shaft... the F28 uses a 1" 14 spline and (if I remember) ALL others use a 3/4" or 13/16" (basically the same) 24 spline.

I just wanted to clear that up because we are getting clutch kit made and I was going to send exist3nce a 24 spline kit until I saw his compareson pics.

Post by **PrecisionBoost** » Fri Mar 14, 2008 1:22 am

Well...... here are the measurements for the three gearbox input shafts I have in storage.

F28 -> 24.5mm
F16 --> 19.7mm
M32 --> 21.8mm

I would imagine that the F16 is 20mm and M32 is 22mm

F28... well I would guess that it should be 25mm but I have to think a 1" 14 spline will work ( since 1" = 25.4mm )

Of course this is measuring on the outside of the shaft so it's possible the measurements aren't perfect (since it's not a round surface )