Manual conversion problem

[jstewart]

I understand that putting a manual transmission behind these turbo'd engines doesn't work well.

I did some searching here, and saw some responses to that effect.

My question is, I have driven other cars that are turbocharged with manual trannies. What is it that is different in those that makes them work, that is not in the GN?

Anyone an expert on this?

 

[turbofish38]

I've asked that question many of times. Heck even the Callaway TT Corvette had a stick. I guess one of the answers is because nobody has successfully done it. All I've read is where somebody stuffed a stock weak T-5 or something equally wimpy and than got frustrated when it broke. Others give you the lame excuse of crankshaft thrust bearing is the limit. Okay? Than how the heck did they do it in NASCAR and Indy? Yeah I know a Stage2 uses different specs for those bearings.

You may now open the floodgates of opinion and conjecture.

 

[usetaboost]

TOtally way off base but I know there is a HUGE difference in an automatic daytona Z and a 5 speed car. And what about all the imports? I've heard a lot of the guys with turbo cars say the automatic versions are almost 1 sec slower on certain models. Maybe it could have something to do with the gear spread and the engine not being in the pwr band long enough, and turbo sizing may have something to do with slower times. Hell I don't know-just talking out of my AZZ. I'll let the experts do the talking now.

 

[TurboDave]

Than how the heck did they do it in NASCAR and Indy? Yeah I know a Stage2 uses different specs for those bearings.

.

I think you answered your own question.

 

[salvageV6]

Since our cars didn't come with a BOV from the factory that's pretty much a show stopper right there.

Actually in most drag races the auto. cars are faster mainly because the auto. tranny is usually smarter than the avg. car driver when shifting WOT. :biggrin:

I think the magazine times are with professional drivers powershifting on the edge, plus they don't own or care much about what's left of the car when they send it back.

If you go watch stick drivers at the track they rarely duplicate the auto. times, let alone the magazine times.

I guess if you really want to shift a mid-size kinda heavy turbo car it can be done, and as they say, you first.

I think it would kinda suck in a daily driver.

 

[turbofish38]

Let me throw another log on the fire with this question. Okay the Buick V-6 is just a Buick 350 minus 2 cylinders. The Buick Big Block shares many of the same qualities as the 350. Basically all Buicks are designed kind of the same. Thrust bearing is in the middle of the engine more or less. How the heck are the V-8 guys with a 3rd pedal getting away with power shifting the heck out of their cars? I dont frequent the V-8 board but I dont recall a lot if any crank and bearing failures when I had a 4 gear GS455. What would happen if you tighten up the clearance there? The BOV and lag issues are easy to solve.

I dont see a need to manually shift when you have a motor that makes more torque than it knows what to do with. Add in a heavy and clumsy handling car. Now I've done a few open track events and I would have given a left nut to have better control of the car just to pick up that extra second or so. I guess I was used to flinging a light 4 cylinder underpowered car through the course. A properly tuned automatic will beat the pants off a stick. Learn to use the torque convertor to power it out of a corner and you'll never have to think twice about what to do with your left foot.

 

[bison]

I understand that putting a manual transmission behind these turbo'd engines doesn't work well.

I did some searching here, and saw some responses to that effect.

My question is, I have driven other cars that are turbocharged with manual trannies. What is it that is different in those that makes them work, that is not in the GN?

Anyone an expert on this?

It could be made to work easily, but its not anywhere near optimal in a g-body which is more for straight line performance. The quickest and fastest street driven turbocharged cars all have automatics in them.

 

[GDNF2ET]

As far as DSMs go ( EVO, Eclipse, Talon ), most of real fast cars are manual shift..I'm talking 8s, 9s, 10s in the 1/4 mile.... The EVO is the best example, simply because it doesn't even offer an automatic.....

DSMTimes.org - Home

This link is for EVOs only.....If you click on ALL CARS on the chart, you get a mix of 1g, 2g and EVO cars..The 1g and 2g cars can be auto or manual, though most are manual..

 

[bison]

As far as DSMs go ( EVO, Eclipse, Talon ), most of real fast cars are manual shift..I'm talking 8s, 9s, 10s in the 1/4 mile.... The EVO is the best example, simply because it doesn't even offer an automatic.....

DSMTimes.org - Home

This link is for EVOs only.....If you click on ALL CARS on the chart, you get a mix of 1g, 2g and EVO cars..The 1g and 2g cars can be auto or manual, though most are manual..

Imagine if they were built around rear wheel drive and an automatic They would be about a half second quicker than they already are.

 

[MikeL.]

here's one that seems to work

check this out. turbo924.com He's putting 560lbs/ft torque at the wheels through the porsche 5sp tranny. That's what's stated in his sig anyway. How cool would that be to have a six speed tranny in a GN?

 

[charlief1]

I think you guys are missing the point, He's asking about road courses from what I'm reading. I don't think any one has used a GN on a road course because of the auto tranny, However, there were several USAC turbo regals used for road course competition in the 80's and they were quite efective.

 

[salvageV6]

Where did you read anything about road courses?

I'd want a good brake conversion for them, long before any transmission conversion. :biggrin:

 

[corsair231]

First, compared to DSM's and a lot of other factory built manual trans turbo cars, our cars have a big engine. There is a lot more weight in internal parts to accel and decel during shifts. Tit for tat our cars tend to rev slower and operate at lower rpms because of this. Add a manual trans flywheel to this and you have even more reciprocating weight to handle everytime you lift to shift and slam the throttle again, plus without a bov, everytime the throttle closes the boosted air backs up, slowing the turbo speed and dropping boost. Basically having to respool the turbo between each shift. Especially troublesome with our larger turbos, comparatively speaking of course.

Anyway, I think GM did a pretty good job of matching everything up in our cars as far as gearing, stall, turbo, and etc. The auto lets us load the car at the line and leave with boost where most manual trans cars, unless there is something like a rev limiter to help build boost, leave off of just rpm. Our cars are known for boatloads of torque and the converter helps to multiply the effect for launch. This helps to move our heavy cars off of the line. During shifts the automatic allows the engine to remain at wot, keeping airflow and turbo speeds up, keeping it in the powerband. There is slippage in converters and some trans are tuned for softer (slower) shifts and that is one reason many manual trans cars are faster and trap better than there auto counterparts. Once you add lockup to the mix that evens the field on the big end by having less slip than a clutch does. Plus like it was said earlier, automatics don't miss shifts.

Could our cars be faster with a manual? A heavily enough modified and specifically built car may benefit from a manual trans but for drag racing and normal street driving it's hard to beat our combos as they came from the factory.:biggrin:


P.S. On many cars, DSM's included, manual trans models are not the same as their auto versions. They have things like larger cams, injectors, turbos, different exhaust, gearing, and even totally different engines and different power ratings so it is not always an apples to apples comparison.

 

[GDNF2ET]

P.S. On many cars, DSM's included, manual trans models are not the same as their auto versions. They have things like larger cams, injectors, turbos, different exhaust, gearing, and even totally different engines and different power ratings so it is not always an apples to apples comparison.

This is why I posted the Evo track times..

 

[corsair231]

There is supposed to be one of, if not maybe the fastest dsm auto in the country in Charlotte. From browsing his posts and other discussions I think most of the problem with the auto cars is parts availability and cost. They were talking about $5K+ for just a converter. From what I understand, it's easier and cheaper to make the sticks faster and they are more dependable (comparitivly speaking) at that level. So that is what everyone builds. Until you go to full out race cars which convert to rwd and powerglides, th350's or Lenco's .

 

[GDNF2ET]

Automatic dsms are in the tens with $500 restalled stockers.... I would like to known more about this $5000 dollar converter though....Maybe that is what Brent Rau has on his 6 second powerglide?

 

[corsair231]

Not sure of what brand converter or the setup but it was discussed on a thread about an 8 second build in where someone was going to throw someparts together and run those times but the guru's were trying to straighten him out on how it's not that easy.

 

[unix_punk]

Don't know if you guys are familiar with AMS, they're a DSM shop out by me, they went from always using manuals to recommending autos on all of their 1g and 2g race builds... The thing about those cars is the stock auto can handle so much power it only makes sense to run it instead of rebuilding the weak manual trans every couple of months...My friends have been down this road for a long time. The thing they have that allows them to be consistant with a manual is a no-lift-to-shift option which is a clutch-in rev limiter basically. When you power shift, the ecm sees you push in the clutch and kicks in a rev limiter for a split second during the shift to put the rpms where you want them when you're done with the shift, no boost loss there... Thats another main point for running the autos, no need to worry about losing boost if you can't or dont want to power shift with the no lift to shift programming. Just my opinion...