Turbo Optra - Now on tuned Haltech @ 225whp

[PrecisionBoost]

With regards to the rating F28 = 280lbft it's not a number from the Getrag factory it's just a general guideline in use throughout the UK and Europe as estimated power handling.

One thing is for sure.... the higher the number the larger the handling capacity.

The F28 may only be rated for 280lbft but the weak link is the 4wd system..... once converted to 2wd they have much higher power handling capacity.

Based upon my talks with a UK race tranny expert.... the F28 will take a punishing 350lbft of torque all day long if it's rebuilt with care..... which means blueprinting, polishing and nitrating the components.

So in my opinion an average F28 should be fine in around the 280ft lb to 350ft lb range..... but it depends on what your doing.

If your drag racing with slicks.... well decrease that number to 250lbft just to be safe

Without slicks I'm sure it would let loose the tires before anything in the tranny would give out.

[DomWoo]

The F40 will require massive amounts of work to make it work..... none of the North america F40 transmissions will mount up.

Basicly the F40 that fits our iron block 2.0L is sold in europe/uk mated up to one of their diesel engines.

There are a number of Fiero guys that have modified the F40 to mate up to a high performance corvette V8 so that it can be used in the Fiero.

Needless to say I don't think anyone has broke one yet.

The biggest problem with the F40 is that the drive shafts are different.... so custom drive shafts are needed.... and there would be tons of fabrication in the way of mounts, linkage and other stuff like that.

So I would not suggest anyone go out and get an F40 yet.....odds are it could cost $5K just to get it to work with our engine.

thats a shame.. because you can pick one up for under 600$ new.. o'well was a thought.

[PrecisionBoost]

Domwoo.... I know.... I'm considering getting an F40 anyways...they are super cheap.

As far as reaching the D20 maximum limit..... well.... just because yours broke at 240lbft it doesn't mean that other D20 will be the same.

Some might break at a lower power... others at a higher power..... you may have had a weekness in one of the gear teeth which others might not have.

If your getting another tranny you might want to consider having it refreshed by a company that does lots of race transmissions.

I would think that the power handling capacity would be greatly enhanced if the gearset was cyrotreated or nitrated (or both if you have the money)

Tom managed to keep his F16 together at 240lbft for a few years..... he ever drag raced with it and it still survived.

He was carefull not to engage max power in the corners..... that puts way more load on the tranny than if your going in a straight line.


Just for the record..... can you explain the events immediatly before the tranny blew?

You might have cracked a tooth a day or two before and it sat there until one unlucky moment when the tooth came loose and got caught up in the rest of the tranny.

Unfortunatly it only takes one to ruin the entire gearset.... if the cracked tooth had simply broken off and fell into the bottom of the pan it wouldn't have been such a mess.... but I would guess based upon the pics that the tooth was caught up in the gearset and in turn destroyed the other teeth.

[GsiTurbo]

While I used F16, my power output at that time was 198ft-lbs and 176hp (both numbers at the wheels). With F20, I run 248ft-lbs and 197.5hp at the wheels for 2 years with no problems other than slipping clutch at the end (factory).

[kinkyllama]

Based upon my talks with a UK race tranny expert.... the F28 will take a punishing 350lbft of torque all day long if it's rebuilt with care..... which means blueprinting, polishing and nitrating the components.

I'd start another post, but this is kinda related. Do you think my F28 will survive with 255mm R compounds, 300lbsft tq at the wheels out on the track? If not how much are blueprinting, polishing, and nitratiing and which single ones have the best results?

[Tractor]

Hi, from santo domingo

I want to clarify something, the number “280” in the F-28 does not refer to pounds by foot, but refers to Newton meters.

The standar power for the
C20NE is 115 CV and 158 Nm of torque (F16 = 160Nm)
C20XE is 150 CV and 198 Nm (F20 = 200Nm)
and the C20LET is 204 CV at 5,400 rpm and 280 Nm of torque at 3,400rpm (F28 = 280Nm)

So that´s the “official” amount of torque that the gearbox is manufactured to handle.... but in reality they can hold more, although they have smaller useful life

In this link http://media.gm.com/us/powertrain/en/pr ... trans.html
that PrecisionBoost wrote on onother post, it shows that the Maximum gearbox torque of the F-40 is 295 lb-ft ( 400 Nm )

Then based on this, the equivalence would be:

1 Nm is = 0.7375 lbs-ft

So the F-28: 280 Nm=206.5 lbs-ft

I always wanted to know the equivalence between these two measures, until I bump with this link a few months ago


greetings from here

Leopoldo

[PrecisionBoost]

While I used F16, my power output at that time was 198ft-lbs and 176hp (both numbers at the wheels). With F20, I run 248ft-lbs and 197.5hp at the wheels for 2 years with no problems other than slipping clutch at the end (factory).

Oooops... my mistake.....For some reason I was thinking you were allready at 248 ft-lbs with the F16.

Tractor..... I knew about the 28=280NM.... but that's just the "rated" level from Getrag.... most guys simply convert it to lb-ft to get the real world power handling.

Many of the F40 guys are pushing well over 400 lb-ft allready with no problems.

As far as the F28 handling 300 lbsft with R compound out on the track......... I think you'd be close to the limit of the tranny..... it's hard to say..... since your adding the Quaife LSD.

Personally if I were you..... I'd go with roughly 280 lbft just to be safe.... but who knows.... perhaps you might be able to throw 500lbft at it and it won't have a problem.... each tranny is slightly different.... and it completely depends on the exact nature of use.

Basicly blueprinting is the process of taking the entire gearbox apart and tightening up tolerances.... so there is less play in key areas (such as lateral movement)

Blueprinting is something that takes lots of experience and skill..... so it would have to be done by someone in the UK.... and since your tranny has allready been shipped that's out of the question.

I was quoted 2000 GBP to take an F28 and "race prep" it.... which was blueprinting, some shotpeening of very specific parts, and polishing/fixing up casting problems.

Nitrating is expensive..... but Cryotreatment isn't too bad... and I've heard lots of good things about cryotreatment for race use.

[exist3nce]

I have acquired a new transmission and spent most of last saturday installing it. Did an oil change and MTF change again while it was on the hoist. We also removed my two OEM cats and replaced it with a single high flow cat with a new 2.5" pipe. An extension to the dump tube was also fabricated.

For now we retuned it for 7.5 psi on the dyno to make sure the tranny doesn't go again. We've got some ideas to increase HP without increasing torque very much, but I'll post more about that when its concrete.

Peak numbers @ 7.5 psi were: 175whp / 187wtq

Pics of the dump extension and new cat setup:




This metal core cat flows only 50 cfm less than a 2.5" straight pipe and is OBD2 comliant



Also a pic of the car on the dyno.

[kroz123]

hey man nice to hear your back on track. Looks good indeed.

The thread on the toyo tires looks very nice and the widht looks perfect too.

But I have a question (maybe a stupid question) but why is the dump pipe/tube for?

Arvin

[exist3nce]

hey man nice to hear your back on track. Looks good indeed.

The thread on the toyo tires looks very nice and the widht looks perfect too.

But I have a question (maybe a stupid question) but why is the dump pipe/tube for?

Arvin

Thanks man. The dump tube is for the external wastegate. When boost reaches ~7psi all the excess exhaust is "dumped" out of that pipe to ensure the boost doesn't climb any higher. Many turbos come with an internal wastegate which performs the same function within the turbo where it just lets the exhaust gas bypass the turbine when boost reaches the desired level.

[kroz123]

Ohh Ok thanx for the info man, I will have to fab one too cuz I also have an external w/g.

Mines coming along slowly but now my timing belt begun to make noises so I will have to change that first and also all the other things included with the belt.

Arvin

[exist3nce]

So I went to the track yesterday with a couple friends just to get some numbers and confirm what I've been estimating.


I got a 15.46 @ 94.38 MPH ------> 7 psi / 175 whp


....Not the best ET, but it was a gentle launch. Also I had about 100lbs of crap in my car (spare tire, subs & amp, tools, and too much other junk!) so I think if I had taken that out, I could have hit a 96 MPH trap speed.

Heres the timeslip:



On one of my last runs I tried to launch, but was way too aggressive and wheel hopped really bad in 1st gear......... now my "new" transmission has gear whine

[Nemasys]

Slow response time hehe just folling with ya bro, nice run!

[kinkyllama]

S

I got a 15.46 @ 94.38 MPH ------> 7 psi / 175 whp


....Not the best ET, but it was a gentle launch. Also I had about 100lbs of crap in my car (spare tire, subs & amp, tools, and too much other junk!) so I think if I had taken that out, I could have hit a 96 MPH trap speed.

On one of my last runs I tried to launch, but was way too aggressive and wheel hopped really bad in 1st gear......... now my "new" transmission has gear whine

I think you could do better. I managed a 16 flat on less mods than I have now. Though that was according to my gtech which is supposed to be very very accurate with all the right info which I had but who knows.

I dont know crap about drag racing but what was your 60' time?

[jorge]

Nubira 2.2 do 14.7 @ ... at 4 psi and 145 or 146 whp... You can run 14 low whit that hp.