5 speed behind a TR engine

[vintageracer]

I have been a v8 Buick guy for a long time. Just got back from the GS nats and had a great time. I have a new project I am beginning that is a heavily modified 63 split window Corvette. It has a mandrel bent, square tube chassis with C4 complete Corvette suspension. Coil overs at all four corners etc. This will bolt under a stock "mid-year" body with 17x8 inch front wheels and 17x9.5 in the rear.

For "motivation" I want something different and a Buick turbo engine fits the bill. Every turbo car I see and all transplants have an 2004R or some automatic. I want to "row the boat" and use a Doug Nash street 5 speed transmission.

What is special or different that is needed to run a manual transmission behind a Buick turbo engine? Why did I not see any manuals at the GS Nats?

Thanks in advance for the help!

Mike
1970 GS Stage 1 Convertible

 

[UNGN]

There is LOTS of info on this in the archives. Suffice to say, a non stage II 3.8L is ill suited for a manual transmission. Way too many downsides to make it worth the expense, complexity, breakage and lack of performance.


A T/A block, a good set of heads, a steel crank and a $5000 Liberty 5 speed may work.

Short of that, the results will be pretty disappointing.

 

[bruce]

Originally posted by vintageracer
I have a new project I am beginning that is a heavily modified 63 split window Corvette. It has a mandrel bent, square tube chassis with C4 complete Corvette suspension. Coil overs at all four corners etc. This will bolt under a stock "mid-year" body with 17x8 inch front wheels and 17x9.5 in the rear.

I want to "row the boat" and use a Doug Nash street 5 speed transmission.

What is special or different that is needed to run a manual transmission behind a Buick turbo engine? Why did I not see any manuals at the GS Nats?

Throttle lifts for shifting aren't well suited for MAF Turbo cars, IMO.
It would take some serious calibration work to get it really right, again, IMO.

How about a 4L80E with a paddle shifter?.

 

[vintageracer]

Thanks for your quick responses! I knew there must be some good reasons for a lack of manual shifters in turbo cars and now I know!

Is the MAF the problem? You certainly see a lot of manuals in turbo ricer's. Are they using MAP's or other types of computer controllers to overcome "lift" issues when shifting?

I like the paddle shifter idea. Could this be done with a 2004R? I had not planned on "cutting" the floor boards for this project. This would be required to install a 480LE.

Thanks for your responses and neat suggestion!

Mike
1970 GS Stage 1 Convertible

 

[Turbo6inKY]

Originally posted by vintageracer

Is the MAF the problem?

No, the MAF is not the problem. The problem is intake reversion. When you lift the gas on a regular Turbo Buick, the throttle plate closes. The charge air that's already passed the maf, but not made it to the throttle body slams into the throttle plate and reverses direction.

The air flying backwards through the intake slows the turbocharger down, even makes it turn backwards.

This isn't a big deal for automatic cars, as they don't drop boost on gear changes, but if you where lifting the throttle to change gears on a manual, the lag induced by the reversion would be unbearable.

The solution is a blow off valve. It releases the pressure and prevent the reversion. However, a lot of the blow off valve on the market vent to atmosphere. That air has already been metered by the MAF, and dumping it to atmosphere will really screw up the mixture.

The solution to that problem is a recirculating blow off valve. Instead of venting the pressurized air off to atmosphere, it dumps it back into the intake tract pre-turbo but post-MAF. That way, when you lift the gas, the BOV opens and the air just makes a circle until the throttle plate opens again.

Or, relocate the MAF to just ahead of the throttle body, so that the charge air doesn't get metered until it actually gets there. That way you can use a regular BOV without having to worry about plumbing the recirculation piece.