Cryogenic treatment (Page 2/3)
IMSA GT AUG 26, 06:17 PM

quote
Originally posted by BingB:

So the main weakness is in the bell housing and the bell housing is aluminum.




Yes. As mentioned by Joe, don't do any clutch pops or burnouts.

[This message has been edited by IMSA GT (edited 08-26-2024).]

pmbrunelle AUG 26, 06:22 PM

quote
Originally posted by Dennis LaGrua:
At Carlisle I had the pleasure of speaking to John Schinella and John Calles who were with the GM/Fiero development team back in the day . I asked what opinion did they have on V8 swaps -that were mated to the Getrag. They confirmed that the Getag is a light duty transmission reliable for only 170-180ft lbs of torque. To use that box with a powerful V8 engine is not following design rules. I did a 3800SC swap for a guy about 10 years back . That was only a 260 HP engine. He insisted on having the stick, used the power and one day he shattered the Getrag case to pieces..
I don't believe that there is any way to strengthen that transmission for high performance use with any engine other than the 2/8L/3.4L V6 engines.
IMO, do a powerful engine swap the right way following good design rules. As boring as they are to some I only use automatics.




quote
Originally posted by Frenchrafe:
How come I don't shatter mine?
I do use racing oil, though that won't have a lot of effect on internal shaft end loads.
Maybe it's just not dropping the clutch like a grunt!
Feather that loading up with your left foot....



OEMs and hobbyists typically have different design rules.

For the factory car, perhaps 1/10000 transmissions will break and need replacement during warranty.

If you double the engine's torque, perhaps 1/10 transmissions will fail early.

1/10 would be catastrophic for an OEM, costing way too much money and tarnishing the reputation of the brand.

A hobbyist may choose to run with 1/10 odds, perhaps never having a problem (especially if driving carefully), or being unlucky and experiencing a failure.
Dennis LaGrua AUG 26, 06:59 PM

quote
Originally posted by pmbrunelle:


OEMs and hobbyists typically have different design rules.

For the factory car, perhaps 1/10000 transmissions will break and need replacement during warranty.

If you double the engine's torque, perhaps 1/10 transmissions will fail early.

1/10 would be catastrophic for an OEM, costing way too much money and tarnishing the reputation of the brand.

A hobbyist may choose to run with 1/10 odds, perhaps never having a problem (especially if driving carefully), or being unlucky and experiencing a failure.



Over the years we have read many Getrag blowup stories on this forum. I can name at least four that I know of. Pat Ciarcia a drag racer back in the early 90's ran a small block Chevy. It was very powerful and he blew two Getrags in 1/4 mile runs before finally going to a modified JPT Automatic. You can certainly swap any V8 or super V6 engine that you want in your stick Fiero and it will hold up fine for normal driving and the occasional WOT run. I would not just not do it for regular high performance driving.
I make not make any friends by saying this but with the coming of good high efficiency 4-9 speed automatics manual transmissions are now nearly obsolete. You can only get them on very few new vehicles.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

fieroguru AUG 26, 08:15 PM
If you don't drive them like a 16 year old, and you run normal tires (not super sticky tires) with a rebuild and properly differential bearing clearances, they can be reliable in the 250 to 300 rwtq range.

Once you are north of 400 rwtq, even with rebuild and proper diff bearing clearances, the case fails in short fashion.
https://www.fiero.nl/forum/...120111-2-100156.html

Between the two ranges, results will vary.

Even built autos have a limited life span, especially when they are pushed.


pmbrunelle AUG 27, 08:50 AM

quote
Originally posted by fieroguru:

If you don't drive them like a 16 year old, and you run normal tires (not super sticky tires) with a rebuild and properly differential bearing clearances, they can be reliable in the 250 to 300 rwtq range.

Once you are north of 400 rwtq, even with rebuild and proper diff bearing clearances, the case fails in short fashion.
https://www.fiero.nl/forum/...120111-2-100156.html

Between the two ranges, results will vary.

Even built autos have a limited life span, especially when they are pushed.




For those who are unaware, "rwtq" is a bit of a misnomer here. When we are talking about the final drive thrust force breaking the case, then it is the actual rear wheel torque (i.e. engine torque * speed gear ratio * final drive ratio) that counts (this is in the thousands of lb*ft).

Now I bring up the idea of torque reduction in 1st gear to help save the transaxle. Depending on the engine setup, this can be done with a drive-by-wire throttle, or with electronic boost control on the turbo, or simply with a laggy turbo that does not spool up in 1st gear.
82-T/A [At Work] AUG 27, 09:16 AM

quote
Originally posted by pmbrunelle:

For those who are unaware, "rwtq" is a bit of a misnomer here. When we are talking about the final drive thrust force breaking the case, then it is the actual rear wheel torque (i.e. engine torque * speed gear ratio * final drive ratio) that counts (this is in the thousands of lb*ft).

Now I bring up the idea of torque reduction in 1st gear to help save the transaxle. Depending on the engine setup, this can be done with a drive-by-wire throttle, or with electronic boost control on the turbo, or simply with a laggy turbo that does not spool up in 1st gear.




Thinking about myself here... I'm building up a 3.4 in which I intend to hit or just break 200hp, which means I'll probably get around 240 ft-lbs of torque.

I'm going to be going with a modified Getrag that will have 3.94:1 final drive (just took delivery of an Oldsmobile SCX 5-Speed Getrag). That car came stock with 190hp and 160 ft-lbs of torque.

I haven't done a clutch drop in anything since I was like 24 (and I'm now 23 years older)... so my assumption is that even power shifting (hard shifts from 1st to 2nd), my Getrag should be good to go?
La fiera AUG 27, 12:42 PM
Going back to the original question, I've been using the cryo method for about 15 years now and everything I've gotten threated have not failed, yet! I just got 3 crankshafts cryoed for the other 3 engines I'm working on. You can't see any physical changes on the parts because everything is within the microstructure of the parts but in the case of the crankshafts which 2 are cast and one is forged, I did a sound test before and after and I can hear that all three have a slight higher frequency. I also have done camshafts, lifters and aluminum connecting rods. And yes, cryo does work on aluminum.
fieroguru AUG 27, 05:30 PM

quote
Originally posted by pmbrunelle:
For those who are unaware, "rwtq" is a bit of a misnomer here. When we are talking about the final drive thrust force breaking the case, then it is the actual rear wheel torque (i.e. engine torque * speed gear ratio * final drive ratio) that counts (this is in the thousands of lb*ft).

Now I bring up the idea of torque reduction in 1st gear to help save the transaxle. Depending on the engine setup, this can be done with a drive-by-wire throttle, or with electronic boost control on the turbo, or simply with a laggy turbo that does not spool up in 1st gear.



Rwtq is a simple/measurable number people can use to compare if they are in failure zone, based on prior documented failures. It isn't the force value of failure, just a reference number.

The bearing that exits the party in the torque driven failures supports the pinion gear, so it is before the torque multiplication of the final drive.
BingB AUG 28, 10:38 AM
This thread is a great example of the knowledge that is available through this site.

Look at how many different things have been addressed.

Right now I am back to trying to research the effect on aluminum.
La fiera AUG 29, 10:44 PM

quote
Originally posted by BingB:

This thread is a great example of the knowledge that is available through this site.

Look at how many different things have been addressed.

Right now I am back to trying to research the effect on aluminum.



https://hekimianracing.com/...ryogenics-explained/

Here you go BingB. Just read through this.