Rajay (BAE) turbo rebuild stupid question

[opethmike]

Sorry Dave, but a good EFI system is not THAT big of a project.

[FABombjoy]

Even without full blown EFI, there are interim solutions for programmable ignition, as well as programmable KJet control.

[David T]

Unless you have done a few, it is a big project for most people. As for a piecemeal solution, for what you will spend and the time it will take, IMHO it isn't worth it. And after all of that time and work the different systems won't "talk" to each other. No, the way to modernize the car is to do a full-blown EFI, especially if you want to do the turbos right.

[opethmike]

Really? Because I hadn't done one before, and it only took me a few weeks to put it together and get it tuned well through all usage of the car.

I really wish you would stop talking about things you don't actually know about Dave. That 15 minute lecture you gave me at a DMA event about ruining my car by going EFI was plenty enough, but you're still going.

[RamblinDMC]

My plan is a full electronic fuel injection + electronic ignition setup + forged internals so I can turn up the boost.
But that's all going to happen well after graduating GT. For now, I just want to get the turbo installed. I'm not concerned about making a ton of power right now.


I really don't plan on ever selling this car, I have a lot of plans for it

[David T]

My plan is a full electronic fuel injection + electronic ignition setup + forged internals so I can turn up the boost.
But that's all going to happen well after graduating GT. For now, I just want to get the turbo installed. I'm not concerned about making a ton of power right now.


I really don't plan on ever selling this car, I have a lot of plans for it

Then just get the BAE set-up to work as good as you can keeping it as "stock" and original as you can. Keep the boost to 5 lbs or below and you should be OK. Sorry you got caught in the cross-fire between me and Mike, as you can see, doing conversions can bring out strong emotions in some people. One point to mention with the BAE set-up. It is a single turbo system as opposed to the Island Turbo system which is 2 smaller turbos. With the BAE kit you will notice more turbo lag since you are using a larger turbo with more inertia, it takes just a little longer to build up boost. It is also prone to overshoot so you have to watch the pressure and not exceed your upper limit. Before experimenting with control systems you may want to try putting in a blow-off valve. Replacing the cast pistons with forged ones will get you some more boost but all you are doing is moving further down the failure chain. The next point of failure will be the transaxle input shaft. You are going to have to get the one piece shaft. Next you are going to need an intercooler.

[FABombjoy]

With the BAE kit you will notice more turbo lag since you are using a larger turbo with more inertia

You'd think the two kits would take different approaches to spark control. And yet they don't.

What if I told you that I can make 6psi by about 2600 RPM on a 60 trim turbo, which is what the Rajay is?

It is also prone to overshoot so you have to watch the pressure and not exceed your upper limit

Probably because the BAE wastegate is too small and sits perpendicular to exhaust flow. I haven't had the chance to measure it, but it looks undersized to me. I'm running a TiAL 38mm WG and boost control is spot-on. The lower the boost level, the larger the wastegate.

Before experimenting with control systems you may want to try putting in a blow-off valve

On a draw through turbo? Why, so you can introduce another boost leak? Fix the WG if you have boost creep, don't introduce yet another disparate control system.

Replacing the cast pistons with forged ones will get you some more boost

There are a lot of factory turbo motors running cast pistons. For example, most models of WRX. Late model WRX started having ringland issues and those turned out to be... the tuning!

The next point of failure will be the transaxle input shaft. You are going to have to get the one piece shaft. Next you are going to need an intercooler.

No way, you'll pop the heads off the block before you break an input shaft. 300lb/ft is the accepted safe margin (although clearly not a steadfast rule), so you're looking at doubling the amount of air into the motor to make that kind of power. Legend had commissioned new head gaskets and bolts to go with pistons.

I absolutely appreciate the Legend story and what they were able to accomplish with the technology at the time, but they weren't using some sort of magic tech or crashed-ufo-recovered-technology.

This is the formula, an extremely common formula used by engine builders everywere:
1: Add air
2: Add fuel
3: Upgrade what breaks

Legend also had some ideas that have not aged well, like using a knock detector to reduce boost pressure. Well yah, if you're going to make boost adjustments based on knock (not pre-knock like a modern system, for real full-on knock) of course you're going to need forged pistons.

But this discussion has been had before
http://dmctalk.org/showthread.php?49...ll=1#post70875

I was able to address the points in #6 in a programmable and reasonably predictable manner. It doesn't have to be EFI or nothing.

[RamblinDMC]

The overall plans I have for my car do include intercooling, and a manual trans conversion at some point.

This is what I've been calling my "10 Year Plan"

-Rebuild and Install BAE Kit
-Install EFI and Electronic Ignition
-Install an Intercooler
-Wait Several Years to Save Up Money For Next Steps. :/
-Separate body and frame
-Rebuild Engine W/ Forged Internals
-Fix rusty areas in frame + paint
-Manual Trans Conversion

These are all big steps.
And everyone has told me to just buy a manual car. However there's two reasons why I don't want to do that. 1, I'm attached to this car in particular and 2, I like doing things the hard way.

And good news, I have finally fully disassembled the Turbo and I have installed all of the new parts from the rebuild kit into the bearing housing. Today I'm taking it to get balanced.

Pictures to come...

[David T]

The overall plans I have for my car do include intercooling, and a manual trans conversion at some point.

This is what I've been calling my "10 Year Plan"

-Rebuild and Install BAE Kit
-Install EFI and Electronic Ignition
-Install an Intercooler
-Wait Several Years to Save Up Money For Next Steps. :/
-Separate body and frame
-Rebuild Engine W/ Forged Internals
-Fix rusty areas in frame + paint
-Manual Trans Conversion

These are all big steps.
And everyone has told me to just buy a manual car. However there's two reasons why I don't want to do that. 1, I'm attached to this car in particular and 2, I like doing things the hard way.

And good news, I have finally fully disassembled the Turbo and I have installed all of the new parts from the rebuild kit into the bearing housing. Today I'm taking it to get balanced.

Pictures to come...

Installing a turbo into an automatic takes a lot more effort to get it right than on a 5-speed. You have the shift points to deal with and there are only 3 of them compared to the 5-speed. You also have the torque convertor which multiplies the torque. You also have to get the vacuum advance set up to conform to the shifting and the build-up of boost. An EFI system would make all of that easier. I also think you need to reset the order of your "10 Year Plan". If you are doing all of this on a tight budget I would forget the turbo for now and concentrate on getting the basic car in order. If you don't have a donor car with a 5-speed, getting all of the parts to do the conversion can be a challenge. While the conversion can be done it isn't practical. A lot of "bits" for the shifting mechanism and the pedal box. That is why you don't see many done. Faster, cheaper, and easier to just buy and sell 2 cars.

Legend was regularly breaking input shafts after they did cams and pistons and upped the boost. I don't recall Fred saying he had trouble with heads. Strange since Lotus is pushing 350 HP through essentially the same transmission. They had to go with a double-clutch plate set-up to do it! You also have to remember Legend was trying to create a turbo set-up that DMC could warranty for a while. Tuning can go a long way to keeping the pistons from breaking but they didn't have EFI back in the late 70's-early 80's.

[FABombjoy]

Legend was regularly breaking input shafts after they did cams and pistons and upped the boost

If that's true, it's probably because they swapped to sintered copper/bronze discs while waiting for uprated Renault clutches to arrive. I'm sure they chattered like an sob could easily contribute to shock damage.

They also had been delivered cars featuring "no less than three different types of input shaft splines". Their relined metallic clutch was a 10 spline and there is probably a good reason that Renault stopped making 10 spline input shafts.

I would not take anyone's recollections as any form of evidence regarding transmission strength. The data available via 30+ years of motor swaps and modern turbo conversions is far more useful.