RB25DET AWD swap into 1990 CQ

CQquattro · Jul 4, 2015

Sorry, haven't started yet the engine swap yet, but seriously entertaining the idea for my CQ hill climb project. Did some searching on the web and haven't found anyone who has done this yet, so why? Legendary power, strength, reliability, drivetrain, and the engine sound!

Not to mention the engine would no longer be hanging over the front of the axles, so I'm very curious how it would affect the vehicle dynamics.

Major hurdles I foresee:

1. The firewall and transmission tunnel will need to be heavily modified. The RB trans is wider, taller, longer, and has a transfer case w/external front driveshaft. I may not be able to have a passenger seat.
2. The RB will need to sit much further back to accommodate the correct front driveline. Since the RB has a front diff with driveline positioned at the center of the motor, I may need to modify the oil pan and move the diff farther towards the rear of the engine.
3. Lots of other custom stuff, motor mounts, subframe, steering rack relocation, tierod/steering knuckles need a redesign, front axles, driveshaft. List goes on.

I'd like to know your guys' thoughts. The RB engine and trans is relatively cheap for great performance in just stock trim, which is why this is so appealing. I'd be using an engine and trans out of a R34 GT-S skyline. Pic included

The German · Jul 4, 2015

Most folks here seem wedded to only using VAG powerplants so I'm sure you will catch some flak for using a Nissan motor, but I would say if you have the skill to pull it off then go for it! It makes all the sense in the world to try and move the motor back and improve balance. As you note there will be a significant amount of fabrication involved.

audifreakjim · Jul 4, 2015

Have you throught about an 07k Swap instead? I can see the desire to use the driveline, but an 07K would give you less weight, more room, and better performance than the traditional I5.

Basically the next best thing to above, without having to modify the tunnel.

CQquattro · Jul 4, 2015

Thought about doing the o7k, I actually have one on hand that I'm trying to sell if anyone is interested!

The German · Jul 4, 2015

I think the driveline configuration drives the need modify tunel and firewall, so I don't see the 07k having any advantage there. The 07k has to be adapted for longitudinal applications as well. The skyline transant is unconventional but seems like a reasonable idea.

MikkiJayne · Jul 4, 2015

Seems like an awful lot of work to shoehorn it in to an Audi when it would be much easier to put it in something that has the right proportions in the first place (ie something that started off RWD - 944, E30/36 etc?).

That said, I will follow with great interest if you do try it!

speeding-g60 · Jul 4, 2015

some inspiration for you then.

Scirocco with the same running gear you wish to do.

CQquattro · Jul 20, 2015

Well it's happening. Rb25DET Neo engine and awd transmission arriving in the next few days from Canada. Started cutting out the firewall and transmission tunnel last night, and mocked up the location of the new firewall. It's gonna be one hell of a squeeze. More pictures as progress continues!

The German · Jul 21, 2015

Cool! watching with great interest.

jordantr · Jul 21, 2015

Interesting. I wish you luck sir. You've seen the R14 right?

http://www.nissanroadracing.com/showthread.php?t=2680

I'm curious what your power goals are with it? Final curb weight?

vr-vagman · Jul 21, 2015

speeding-g60 said:
some inspiration for you then.

Scirocco with the same running gear you wish to do.

.................

These guys are my close friends. The whole runing gear is sourced from an R32 and adapted to the 'rocco's chasis. The gearbox tunnel is also taken from the same R32. They purchased front clip from Canada.
The drag racing is their passion and hobby.
https://www.facebook.com/heedauto" onclick="window.open(this.href);return false;

CQquattro · Jul 21, 2015

I have seen the R14 build, very cool! That's what really got me motivated, seeing as I could modify the oil pan/front diff location worst case scenario.

Another issue I just discovered (although a blessing in disguise I think) is how the r34 awd system works. The attesa e-ts awd system uses the wheel speed sensors and a centrally located g sensor to monitor how to best distribute power from rear to front. It's almost entirely rwd unless the attesa ecu sees wheel slip or heavy cornering, then it sends power to the front via an electronically controlled hydraulic pump and slave cylinder operating a multiplate clutch in the center diff. Since I won't be using the Nissan speed sensors or g sensor, I can't use the electronic control of the awd.

Instead, it will be full time rwd or full time awd which can be changed at speed with the simple pull of a lever. Pretty pumped about that

MikkiJayne · Jul 22, 2015

CQquattro said:
It's gonna be one hell of a squeeze.

No kidding!

Looks like it'll be a 2-seater now then, with the front seats moved right back racecar style so you have space for pedals etc?

It would actually be relatively straightforward to contrive an electronic control system for the AWD based on your description, using the front and rear ABS sensors to determine axle speeds and output something to control the clutch. Levers would also be cool though

EdWindows · Jul 22, 2015

Love RBs! I approve of this build. :woowoo:

CQquattro · Jul 23, 2015

Engine and trans got delivered today, wasted no time and got the engine positioned in the bay. Very excited to see that it fits without a hiccup, plus I have more room than I thought at the rear, allowing me to have the firewall closer to the stock location. Look how much room I have for activities in the front!

dalspaugh · Jul 23, 2015

Cool! watching the progress of a fellow eastern mass CQ build.

The German · Jul 24, 2015

sweet! and look how little motor is ahead of the front axle!

MikkiJayne · Jul 24, 2015

'activities'

Rallyfreak202 · Jul 24, 2015

I applaud you for putting a bad ass non-VAG engine in the CQ! Watching this project!!

CQquattro · Jul 26, 2015

Needed an engine dolly, so made this one with an old creeper. Fully height adjustable to position the motor and trans just right in the chassis, so I can fabricate the mounts, firewall, and transmission tunnel accurately.

A bit more cutting needed on the body, then I'll slide this into place and start constructing the firewall.

CQquattro · Aug 3, 2015

Some more progress, got the engine and trans positioned where they need to be, and started mocking up the intercooler and radiator location. They will be angled with an exhaust vent coming out of the hood.

Also fabbed up a "plug" for a carbon intake plenum I'll be making.

Chopped · Aug 3, 2015

I got so much greif when I mentioned this swap for a race car. Glad to see someone thinks the way I do. I'll be watching this one!

CQquattro · Aug 5, 2015

Vehicle dynamics question, any insight?!

Last night I started mocking up the placement of the new steering rack, I'll be using one from a 240sx. It is getting mounted to the audi subframe, right about where the OEM mounts are for the transmission. There is a hump in the RB oil pan that allows the steering rack to sit in this location (stock location for RB). However, the subframe gets in the way of the tierods during suspension travel & full lock. If I install a 0.5" spacer between the frame and subframe (moving the subframe down 0.5") I get enough clearance. My question is, what happens to my suspension geometry? It's obvious the control arm bushings will be moved closer to the ground, and that will change the resting angle of the control arm, but is that it? I'm trying to figure out if my center of gravity is lowered or raised? I believe the car will maintain the same ride height, is the control arm angle the only thing changing?

dalspaugh · Aug 5, 2015

They way I see it, yes. resting angle is the only change I can see. The ball joint at the bottom of the spindle will take the extra angle up. I guess if you want to get really precise, it will actually change the camber slightly (positive) because the arm is a fixed length, and you are moving it in an arch around where the ball joint wants to be.

I think that made sense...

CQquattro · Aug 5, 2015

Yes I agree, camber will change ever so slightly since the ball joint to bushing angle will be slightly different (thinking triangles and hypotenuse length) If anything else I believe my cg will be slightly lower but probably negligible. I had a friend try to convince me my cg would be raised, since the car is getting raised .5", I knew that couldn't be right!

dalspaugh · Aug 5, 2015

CQquattro said:
Yes I agree, camber will change ever so slightly since the ball joint to bushing angle will be slightly different (thinking triangles and hypotenuse length) If anything else I believe my cg will be slightly lower but probably negligible. I had a friend try to convince me my cg would be raised, since the car is getting raised .5", I knew that couldn't be right!

haha yeah I guess CG would be lowered ever so slightly because you are adding weight down low.

RB25DET AWD swap into 1990 CQ

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