Help me build a turbovan into a drag car!

[Tim Kish]

Stock BOV is junk and leaks pretty bad above 15psi (or just blows apart). we joked that it sounded like my car would gobble like a turkey when you'd lift with no blowoff valve but in the early 90's we didn't know better. I think a good external wastegate may help with the restriction in the system with a stock mitsu.

I'm using the Mopar Performance (truck style) master cylinder with the front and rear paired. As was pointed out to me the master cylider itself is biased in ite pressure output at the front and rear ports so it does matter which way it is plumbed. I found that mine was originally backwards and seems to work better now. The correct plumbing is that the port nearest the firewall is for the front wheels, with the further port to the rears. An additional Wilwood flow control valve is installed in the rear line to restrict rear brake apply rate since the back half of mine is pretty light.

[ShelGame]

Stock BOV is junk and leaks pretty bad above 15psi (or just blows apart). we joked that it sounded like my car would gobble like a turkey when you'd lift with no blowoff valve but in the early 90's we didn't know better. I think a good external wastegate may help with the restriction in the system with a stock mitsu.

That reminds me - StockerVan, if you're going to race a Mitsu turbo; shim the wastegate actuator. From the factory, they are setup loose so that they leak a little exhaust thru the wastegate port. I put ~0.09" washers between the actuator bracket and Compressor housing to force the wastegate puck closed.

Tim - I thought about building a header with an external wastegate, but there was some question as to whether or not it would be legal. I decided not to risk it and just shimmed the Mitsu wastegate.

[StockerVan]

I wanted to point out something though that I caught earlier in this thread. You said you are going to weld the diff. You might want to check the rules because I think that not only is this dangerous, it is also illegal, especially for FWD! If you couple a manual rack with a welded diff, not only is it going tobe near impossible to turn, but if something were to go wrong, you are going to #1 NOT be able to do much about it, and #2 if you try you are probably going to end up with a broken thumb or wrist. Not good in either case, so I don't reccomend it. But, it's your call....

To be completely honest, i too thought this was illegal. I just reread that section of the rule book and did not see anything pertaining to welded diffs. As far as not being able turn... people install spools in cars all the time and still are able to turn and this works exactly the same way. If I do not feel like the car can safely turn, then I will not be running it without power steering. Period.

It's funny, a lot of drag racers tell me that welding is dangerous. But go talk to some road racers. This is an extremely common and legal modification for road racers who do not want to spend the money on an LSD. I am talking lower class cars like Imporved Touring, but it is still common and legal. You'd think going around corners at speed with a locked diff would be far more dangerous. But they do it, and safely.

I will not be welding it in my garage, I will be taking to it a very competent machinist/fabricator and have it done properly.

Anyone have input on this?

Sean - I'm not mad at you, more frustrated with some of the other classracer guys that lack common sense is all!!! The Turbo Mopar guys are probably the best group of people your ever going to be associated with, always willing to help. I've been part of this community for 20 years and just can't get away from it.

These guys are 100 times more helpful than any stock or super stock racer I have ever encountered. They share any information they have willingly and freely, to benefit all. Stock racers think that their knowledge is some top secret, mission impossible, type of information and dont' give it away. I really like this community and I just got here.

That reminds me - StockerVan, if you're going to race a Mitsu turbo; shim the wastegate actuator. From the factory, they are setup loose so that they leak a little exhaust thru the wastegate port. I put ~0.09" washers between the actuator bracket and Compressor housing to force the wastegate puck closed.

Tim - I thought about building a header with an external wastegate, but there was some question as to whether or not it would be legal. I decided not to risk it and just shimmed the Mitsu wastegate.

I don't know if I was supposed to share this, it came to me through PM. I also don't know if it helps.

But I was told that that mid 80's volvo 740s have a blow of valve that does not leak like these.

Since I know ZERO about these cars i don't even know if it's something that would be easy to adapt, just passing along some info i was given.

Shel, I was also told if I use one of your cals I do not need to Grainger valve. Is this true, and why?

This is fun, I am learning so much.

[turbovanman²]

To be completely honest, i too thought this was illegal. I just reread that section of the rule book and did not see anything pertaining to welded diffs. As far as not being able turn... people install spools in cars all the time and still are able to turn and this works exactly the same way. If I do not feel like the car can safely turn, then I will not be running it without power steering. Period.

It's funny, a lot of drag racers tell me that welding is dangerous. But go talk to some road racers. This is an extremely common and legal modification for road racers who do not want to spend the money on an LSD. I am talking lower class cars like Imporved Touring, but it is still common and legal. You'd think going around corners at speed with a locked diff would be far more dangerous. But they do it, and safely.

I will not be welding it in my garage, I will be taking to it a very competent machinist/fabricator and have it done properly.

Anyone have input on this?

The issue is FWD, you have axles that aren't really designed for that and can snap and with a welded diff, going by what I've read, can pull quickly and severely that you might not be able to stop it-edit, if an axle snaps while accelerating.

Shel, I was also told if I use one of your cals I do not need to Grainger valve. Is this true, and why?

This is fun, I am learning so much.

You should run an MBC as the Mitsu is a very hard to control, I mentioned earlier to run a Turbosmart controller.

[ShelGame]

But I was told that that mid 80's volvo 740s have a blow of valve that does not leak like these.

Since I know ZERO about these cars i don't even know if it's something that would be easy to adapt, just passing along some info i was given.

Shel, I was also told if I use one of your cals I do not need to Grainger valve. Is this true, and why?

This is fun, I am learning so much.

I don't know about the Volvo BOV, but I've read that the Bosch BOV used in the Saab turbos from the late 90's are good for ~20psi. But, they don't seem to have a vacuum port - which I think would be required to hook it up to the vac bard on the throttle.

With my cals, you can use computer controlled boost or a grainger. Whichever way you want to go. I set my cal up to use computer controlled boost because I originally assumed it would be more accurate than a mechanical boost controller. I'm not so sure that's true, based on my datalogs. I see about +/- 1psi range from the setpoint. I've never datalogged a manual boost controller, so I don't know how accurate they are. I'm working on the computer accuracy, though.

[StockerVan]

The issue is FWD, you have axles that aren't really designed for that and can snap and with a welded diff, going by what I've read, can pull quickly and severely that you might not be able to stop it.

This makes sense to me. The thing is... guys are running a spool. And a spool is going to do exactly the same thing, only slightly worse. Since the spool is lighter, the hit at the launch is that much harder on the axles.

Welding the diff and installing a spool put the exact same forces on the axle. Both wheels get even torque and turn at the same speed.

Are you guys running spools installilng aftermarket axles? Do they even exist?

Do you think it would be possible to make something similair to C-clip eliminators installed on every RWD car with a spool?

[turbovanman²]

This makes sense to me. The thing is... guys are running a spool. And a spool is going to do exactly the same thing, only slightly worse. Since the spool is lighter, the hit at the launch is that much harder on the axles.

Welding the diff and installing a spool put the exact same forces on the axle. Both wheels get even torque and turn at the same speed.

Are you guys running spools installilng aftermarket axles? Do they even exist?

Do you think it would be possible to make something similair to C-clip eliminators installed on every RWD car with a spool?

I know, based on others experience, I don't know if I would trust a spool, welded diff in a FWD car, maybe if you upgrade the axles, which are available at aprox $1000 a set.

The axle just slides in, no need for any type of c-clip or form of retainers, they are held in place by spring pressure from the inner cv joint.

[Captain Chaos]

I remember reading stories of welded diffs and I seem to remember the problem being when you let off the car wants to move left or right.

[Captain Chaos]

http://www.turbodiy.com/Mopar%20Page...s%20detail.htm

Heres some trans and diff info that may be helpful if you haven't already seen it.

[Captain Chaos]

http://www.turbo-mopar.com/forums/sh...hlight=lockers

[guyd_15]

"But I was told that that mid 80's volvo 740s have a blow of valve that does not leak like these."

I've used these and if your looking for consistancy they pose a problem. They have a little screw arrangement on the top to control seat pressure. When you try to make those small adjustments to control seat pressure the diaghpram ruptures and all consistancy is lost.

I've never been a class racer, but, I'm sure you see my point.

Guy

[StockerVan]

From reading that post and a few others, it looks like guys are running way more power and running even into the 11s on stock axles... although they are doing it with limited slip.

But wouldn't me going 14.0 with a locked diff put less stress on the axles then an 11 second car with a spool? Especially if the 11 second car is dead hooking or not spinning much at all.

I do not want to do anything overly stupid, so I am going to get lots of input before I make a decision on this.

I am not worried about the welds breaking. I will make damn sure that part is done right.

While I'd like to put aftermarket axles in... 1000 bucks? That is completely and utterly ------- ridiculous. For the cost of a spool and axles I could buy a 100% complete and assembled 9 inch or GM 12 bolt. Maybe even shipped to my door for that price. I mean... it's almost offensive.

If I do have to go the route of a spool or LSD it is going to set me back at least a month or two... I don't want to do that.

[turbovanman²]

From reading that post and a few others, it looks like guys are running way more power and running even into the 11s on stock axles... although they are doing it with limited slip.

But wouldn't me going 14.0 with a locked diff put less stress on the axles then an 11 second car with a spool? Especially if the 11 second car is dead hooking or not spinning much at all.

I do not want to do anything overly stupid, so I am going to get lots of input before I make a decision on this.

I am not worried about the welds breaking. I will make damn sure that part is done right.

While I'd like to put aftermarket axles in... 1000 bucks? That is completely and utterly ------- ridiculous. For the cost of a spool and axles I could buy a 100% complete and assembled 9 inch or GM 12 bolt. Maybe even shipped to my door for that price. I mean... it's almost offensive.

If I do have to go the route of a spool or LSD it is going to set me back at least a month or two... I don't want to do that.

I still wouldn't do it, the risk it just too much.

As for the price of the axles, why is it insane? We are a few 100 who would ever buy those axles, there are 100's of 1000's of racers use Ford 9 inch or GM 12 bolt diffs, get the picture?

Same goes for engine parts, we pay for 4 pistons what V8 guys do for 8, the list is endless.

[BF/STOCKER SPIRIT]

Like i said ,lol,you turbo guys are awesome,down to earth,intelegent
as tim,states, but alot of guys ,on classracer,have more money
than common sence,and they could,brag about the stupid subjects.
O'ya tim, kill more 9 sec super stocker,lol, he didtoo!

[Captain Chaos]

off topic: Its almost ridiculous to see the vulgar display of wealth that shows up to a divisional meet. 500k rigs, 100k cars and with all the money the owners have couldn't buy a first round bye run! But they sure do have pretty pit art!

[Tim Kish]

Welded diff and spool do put the same stresses on the axles. More the issue is that you can not get good weld penetration on case hardened gears. I believe it is listed in the general regulations regarding being illegal. We had a debate on Neons.org regarding the "risk" of axle failure resutling in loss of control - this risk is not higher than a RWD car, nor is the in ability to control the car. Most axle failures occur on the starting line. There are enough other transmission/motor related failure risks that do occur more often downtrack that can result in loss of control independent of type of differential. Upgraded axles are always suggested with HP increases but yes they aren't cheap.

[turbovanman²]

Welded diff and spool do put the same stresses on the axles. More the issue is that you can not get good weld penetration on case hardened gears. I believe it is listed in the general regulations regarding being illegal. We had a debate on Neons.org regarding the "risk" of axle failure resutling in loss of control - this risk is not higher than a RWD car, nor is the in ability to control the car. Most axle failures occur on the starting line. There are enough other transmission/motor related failure risks that do occur more often downtrack that can result in loss of control independent of type of differential. Upgraded axles are always suggested with HP increases but yes they aren't cheap.

Good info, thanks.

[StockerVan]

off topic: Its almost ridiculous to see the vulgar display of wealth that shows up to a divisional meet. 500k rigs, 100k cars and with all the money the owners have couldn't buy a first round bye run! But they sure do have pretty pit art!

Winning in stock eliminator is the most gratifying experience of my life. Those guys bring nuclear weapons to a knife fight.

At one national open I went to the final one day, and I had a super stock GT car every round. I took out more than 250k worth of race cars with my 10k car. Very fun!

Tim, that was what I needed to hear. Thank you.

[karlak]

[QUOTE=StockerVan;445653]To be completely honest, i too thought this was illegal. I just reread that section of the rule book and did not see anything pertaining to welded diffs. As far as not being able turn... people install spools in cars all the time and still are able to turn and this works exactly the same way. If I do not feel like the car can safely turn, then I will not be running it without power steering. Period.

It's funny, a lot of drag racers tell me that welding is dangerous. But go talk to some road racers. This is an extremely common and legal modification for road racers who do not want to spend the money on an LSD. I am talking lower class cars like Imporved Touring, but it is still common and legal. You'd think going around corners at speed with a locked diff would be far more dangerous. But they do it, and safely.

I will not be welding it in my garage, I will be taking to it a very competent machinist/fabricator and have it done properly.

Anyone have input on this? QUOTE]

Welding will place lots of stress on c/v's. Parts will tend to fail more quickly. I snapped a couple axles doing this.

[StockerVan]

One question i've been meaning to ask but keeps slipping here is what do do about the alignment.

I am guessing since it is a fwd car, alignment is important.

Since I wont be going around corners, is there any reason not to set camber at 0 degrees?

What about toe?