1UZ swap into Series 2 RX7

[Muzza_NZ]

So the idea was to take a classic RX7 (if such a thing exists) and make a weekend track and show car, by adding a decent engine, brakes, and strengthening up the chassis with a full rollcage. Purists will be up in arms about bastardising a rotary powered weapon, but they’ll just have to get over it won’t they.

Engine wise, the 1UZ was a logical choice, I’d built up a couple previously and there were plenty of options for performance upgrades later on. The plan was to run the Seven on the standard ecu for about 6 months while we ironed out the bugs etc, and while we put together a twin turbo 1UZ with after market ecu, big injectors etc.

Width and lengthwise the RX7 engine bay would easily accommodate the bulk of a 1UZ, but the height posed a problem. The height from the sump to the plenum was about 650mm and in the 7 the critical height from the underside of the bonnet to the crossmember and steering linkage was 530mm. It was pretty obvious that it wasn’t going to fit, so we removed the 1UZ sump and set the engine down on the crossmember to see exactly how much clearance we had (spaced up about 20mm so the crank wasn’t fouling). In the pics below you can see that one of my fat fingers just manages to squeeze between the plenum and bonnet reinforcing.

 

[Muzza_NZ]

None of the sump configurations fit without major mods

We measured up the 3 sump configurations available on the 1UZ and found that none of the sumps would fit without major mods. The centre and rear sumps would have the oil pickup in the centre of the crossmember and steering arm, so they were completely unsuitable, and the back of the front sump wouldn’t clear the crossmember either, so we were going to have to either dry sump it or heavily modify the crossmember. The cost of a dry sump install was going to be over $2.5k, so we flagged that, leaving modding the crossmember as our only real option.

 

[Muzza_NZ]

The dimensions of the sump meant that the modified crossmember would have to form a cradle for it, either by using tubing around the bowl, or by boxing around it with plate.

Given the location of the engine mounts on the 1UZ, the crossmember was going to have to support the weight of the engine, so we decided to overengineer the new crossmember (read – this thing would be real f%#$en strong, more at home on a bulldozer than a ‘race’ car).

The solution wasn’t the prettiest piece of engineering ever, but it was certainly rigid and strong, stiffening up the front considerably. A local engineering firm did the welding after I had tacked it, so that the certifier was satisfied.

Here are a few pics of the mounts, crossmember, and comparison between the original and new members.

 

[Muzza_NZ]

The engine mounts were pretty straightforward, with schedule 40 tubes supporting nolathane bushings and 3mm plate. A slight mod was made to the drivers (RHS) side mount, to clear the Welch plug, which consisted of another piece of 3mm plate with a half circle slightly larger than the plug, cut out. The mounts were welded up by a certified welder as well.

Some people seem to think that the engine mounts are the hardest part on a conversion, I don’t know why, it’s pretty easy once you get the exact positioning of your engine sorted. We just levelled it up using wood and the engine hoist, and calculated the approximate heights and positions of mounting points. Allowing for between 3 – 5mm sag on the nolathane bushings gives you the clearances, then you just mock up the mounts using cardboard or similar. Sometimes it’s an iterative process though, you might find that once you install other engine components like exhaust headers, power steering or air conditioning hoses etc, you have to move and cut things to suit. For that reason it’s best to solidly tack the mounts until you have everything finalised.

 

[Muzza_NZ]

Anyway, the next things that needed sorting were the brakes. I’ve heard of some RX7s using MR2 front ends, or series 4 onwards brake setups. For this conversion, after much deliberation we decided on series 6 callipers and the largest brake rotors (when combined with the callipers) that would fit inside the 17 inch wheels. New 330mm BMW vented disks were selected as they had the right hat offset to mount on the existing RX7 hubs. The original RX7 hubs were cast with the disks and so they had to be machined off before the new ones could be fitted. The new disks were pressed on (backwards) and secured with countersunk M8 screws. The callipers were mounted off the original series 2 mounts with billet aluminium standoffs. You can sort of see them in the pictures.

 

[Muzza_NZ]

the car so far

Here's a pic of the car with the engine in and the brakes on.

Next up is the front air dam and roll cage.

 

[4000GT]

Mate thats awesome. Ill probably see you out at Ruapuna!

What are you doing for ECU?

 

[gloverman]

Hello Murrey - I like the way you have done your engine mounts - should keep the flex to a minimum. Engine bay is a lot different to the series 4/5 which the rear sump motor fits nicely. How does the overall height look? Good typing speed too - Cheers Kelvin

 

[rx7 s1 1uz]

hey mate, looking dam good go the old school 7

check out this web page got a lot of very good product 4 owe cars at a good price, http://www.mrcmfg.com/respeed/catalog/
check out the bushes they are dam lot cheaper than we get them in nz.

i have got the adjustable sway bar all the front bushings, the adjustable coil overs and adjustable top hats and other bits from them

im getting 1 of there stage 2 cross member kits and going 2 fit a steering rack 2 the front of it, this will allow me 2 use a rear sump 1uz and as well upgrade my suspension even more. the standard 1uz i think will still just hit the bonnet but i will be having the 6/71 supercharger sticking out of it anyway.

what gearbox have you got mate

 

[drifty325i]

Nice conversion mate! we should have a meet around xmas for all the chch members ?

 

[4000GT]

For sure... maybe a cruise over the port hills in the work holidays?

 

[Muzza_NZ]

Cheers lads,
Yeah it's coming along nicely. I can't take all of the credit for project, it's me and a mate doing it, he's the one paying all of the bills!

Andrew: Yeah we'll definitely go for a spin at Ruapuna before christmas (damn that's only 11 weeks away and there's so much still to do) ECU is standard initially, will probably go for a Link since they're made in CHCH, but ideally a motec or autronic)

Kelvin: There is very little flex in those mounts. One of the original crossmembers in the pics above had some rough as guts mounts made on it to fit a bloody heavy 350 chev. They were just rubbish. Clearance wise the engine plenum touches the bonnet reinforcing so that will need to be cut out. Ground clearance to sump is 88mm, which is pretty minimal, but the whole setup will be rigid as hell, so all will be fine.

RX7_S1_1UZ: good call on that website, it's got some really sweet stuff there. A better steering rack would be a nice improvement, the box in the S2 is pretty crappy really, and a proper rack would give much better clearance for decent headers too.

Riley: Keen as a bean for a cruise at christmas, the port hills would be a neat place for a photoshoot.

More updates soon, cage should be done this weekend, then rear brakes mounting (S15 silvia rotors, S6 calipers and hilux diff 1470mm hub to hub) gearbox mounts tidy up... ah, the list is too damn long to write here...

Nick 'Muzza' Murray

 

[Muzza_NZ]

front air dam

Here's a couple of pics of the front air dam. It was made by Foxton Reinforced plastics in CHCH. You can see that there's heaps of room for a decent intercooler too. Clearance from the air dam to the wheel is a bit small, so it will need to be modded for final fit up.

 

[drifty325i]

Sweet port hills is the go! That car is going to be some fun

 

[4000GT]

Pity Foxton only make one old VS kit for the Supra

 

[Muzza_NZ]

Just had a look at the VS kit that they do, it does look a little dated.

E-solver - when are you hoping to have your Supra up and running?

I'm just thinking about maybe organising a CHCH meet early on in the new year.

 

[Kev]

Muzza,

Love your work and you are putting thoughts into my head that my wife will hate you for.

One question and just curious, what is the ground clearance measurement from the crossmember to the ground.

Keep up the good work, Kevin

 

[4000GT]

Muzz,

My motor is running, I just have a clutch to setup basically and a couple of little things like speedo to do. Feel free to pop down anytime to check it out. I may not be there but just introduce yourself to the guys and check it out. You cant miss it

I would say it will be legally on the road within a month.

 

[Muzza_NZ]

Howdy Kev,
the original ground clearance was about 150mm from memory, and now it's between 85 - 88mm. Our certification rules are quite lax in that just has to clear the ground if the tyres go flat. Plus it will get adjustable shocks so if necessary we can crank it up for a warrant (if the warrant guy/gal isn't familiar with the LVVTA rules)

4000GT - nice name change Andrew, it suits. I might have to pop down at some stage. I meant to go down there a while back to get some cabling sorted, but ended up finding a really cheap source via the University. One month is pretty good going, I look forward to seeing it on the street.

Muzz

 

[4000GT]

Thanks, I brought the plate since I have a 4000 motor now and taking off the Toyota 3000GT theme

I will be down there tomorrow after work for a while, having to weld the cross member washers on...